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Drainage systems, an occluded source of sanitation related outbreaks

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Drainage systems and its role in sanitation related outbreaks are evident but still occluded once it has been installed. This current review evaluates if drainage systems can cause infections and thus be of clinical concern. A review of the literature was analyzed. Papers, guidelines, and quality management systems have been considered. Adequate sanitation is fundamental and a prerequisite for safe life and productivity. In contrast, malfunctioning sanitation has been reported to cause outbreaks all over the world. In areas with no sanitation, diarrheal mortality is high and has been shown to decrease by 36% after interventions to improve sanitation. Often, infections are faeces associated and when present in wastewater and sewage sludge poses a high risk of infection upon exposure. Hence, there are working safety guidelines and in industries where infection reduction is essential strict quality assurance systems, i.e. HACCP (hazard analysis critical control points) and GMP (Good Manufacturing Practice) must be complied. Healthcare has recently taken interest in the HACCP system in their efforts to reduce healthcare associated infections as a response to increasing number of ineffective antibiotics and the threat of mortality rate like the pre-antibiotic era. The last few years have called for immediate action to contain the emergence of increasing resistant microorganisms. Resistance is obtained as a result of overuse and misuse of antibiotics in both healthcare and agriculture. Also, by the discharge of antibiotics from manufacturers, healthcare and society. One mechanism of development of novel resistant pathogens has been shown to be by effortless sharing of genetic mobile elements coding for resistance from microbes in the environment to human microbes. These pathogens have been sampled from the drainage systems. These were noticed owing to their possession of an unusual antibiotic resistance profile linking them to the outbreak. Often the cause of sanitation related outbreaks is due to inadequate sanitation and maintenance. However, in general these infections probably go unnoticed. Drainage systems and its maintenance, if neglected, could pose a threat in both community and healthcare causing infections as well as emergence of multi-resistant bacteria that could cause unpredictable clinical manifestations.
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S Y S T E M A T I C R E V I E W Open Access
Drainage systems, an occluded source of
sanitation related outbreaks
Kristina Blom
Background: Drainage systems and its role in sanitation related outbreaks are evident but still occluded once it has
been installed. This current review evaluates if drainage systems can cause infections and thus be of clinical concern.
Method: A review of the literature was analyzed. Papers, guidelines, and quality management systems have been
Results: Adequate sanitation is fundamental and a prerequisite for safe life and productivity. In contrast,
malfunctioning sanitation has been reported to cause outbreaks all over the world. In areas with no sanitation,
diarrheal mortality is high and has been shown to decrease by 36% after interventions to improve sanitation. Often,
infections are faeces associated and when present in wastewater and sewage sludge poses a high risk of infection
upon exposure. Hence, there are working safety guidelines and in industries where infection reduction is essential
strict quality assurance systems, i.e. HACCP (hazard analysis critical control points) and GMP (Good Manufacturing Practice)
must be complied. Healthcare has recently taken interest in the HACCP system in their efforts to reduce healthcare
associated infections as a response to increasing number of ineffective antibiotics and the threat of mortality rate like the
pre-antibiotic era. The last few years have called for immediate action to contain the emergence of increasing resistant
microorganisms. Resistance is obtained as a result of overuse and misuse of antibiotics in both healthcare and agriculture.
Also, by the discharge of antibiotics from manufacturers, healthcare and society. One mechanism of development of
novel resistant pathogens has been shown to be by effortless sharing of genetic mobile elements coding for resistance
from microbes in the environment to human microbes. These pathogens have been sampled from the drainage systems.
These were noticed owing to their possession of an unusual antibiotic resistance profile linking them to the outbreak.
Often the cause of sanitation related outbreaks is due to inadequate sanitation and maintenance. However, in general
these infections probably go unnoticed.
Conclusion: Drainage systems and its maintenance, if neglected, could pose a threat in both community and healthcare
causing infections as well as emergence of multi-resistant bacteria that could cause unpredictable clinical manifestations.
Keywords: Sanitation, Drains, Outbreaks, Infections, Resistance, Pathogens
Sanitation is defined by the World Health Organization
(WHO) as: Sanitation generally refers to the provision of
facilities and services for the safe disposal of human
urine and faeces. Inadequate sanitation is a major cause
of disease world-wide and improving sanitation is known
to have a significant beneficial impact on health both in
households and across communities. The word sanitation
also refers to the maintenance of hygienic conditions,
through services such as garbage collection and wastewater
Sanitation is in general inadequate in rural areas and
in developing countries [1,2] while regarded as safe in
the developed countries in the community as well as in
healthcare. However, it is not sufficient to have access to
water and modern drainage systems unless adequate
sanitation is maintained. Quality assurance maintenance
work is implemented in pharmaceutical and food industry
in order to reduce the risk of exposure to the hazards
(e.g. pathogens causing clinical manifestations) in the
disposals. However, in the community or in healthcare,
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Blom Archives of Public Health (2015) 73:8
DOI 10.1186/s13690-014-0056-6
sanitation is not prioritized and often forgotten [3], despite
that wastewater disposal contains increased level of
human microbes and that there are several reports
implicating drains as a source of infection (Table 1).
For instance, in the community the severe acute respiratory
syndrome (SARS) outbreak in 2003 at Amoy Garden was
reported by WHO to likely have been caused by faulty
plumbing due to lack of maintenance causing dry out traps
[4] and in healthcare, Starlander and Melhus re-
ported in 2012 of a minor outbreak of extended
spectrum β-lactamase (ESBL) producing Klebsiella
pneumoniae due to contaminated sink drains [5]. Indeed,
drains are implicated as being a source of microbes
causing infection both in community and healthcare
[6,7]. Breathnach et al. further pointed out that proper
design and maintenance of the wastewater system are
essential to prevent infections at intensive care units
(ICU) [7]. However, its impact on infection rates has not
yet been fully elucidated.
In the current paper, different aspects supporting the
role of drainage systems and sanitation to cause infections
and emergence of resistance are delineated. Aspects
considered are from past and recent outbreaks, from
developing and developed countries, and also, the ways to
prevent spread of bacteria in the working environment, at
wastewater treatment plants, and food industry. Presented
data will hopefully contribute to a better understanding of
the importance of proper sanitation and its maintenance
to prevent infections.
1907 using key words such as sanitation, infection, trans-
mission, drains, sinks, outbreaks, drainage systems, sewage,
wastewater treatment plants, bacteria, virus, resistance,
antibiotics, biofilm, infection prevention, and health care
associated infections. The fact that contamination on
surfaces, transmission of pathogens, and infections must be
prevented not only in health care but also in industry and
in the community led to that experiences from these
disciplines were explored if useful also to health care.
Internet was searched to find news from community
cases and guidelines on what conditions and requirements
that e.g. food industry must comply with as well as workers
at risk of exposure to sewage. Guidance documents were
found at the databases of e.g. World Health Organization,
Health and Safety Executive (UK), Centers for Disease
Control and Prevention (CDC), Atlanta, GA and quality
management systems were found by searching God
Manufacturing Practice and hazard analysis critical
control points (HACCP). Also, regulations from authorities
such as Environmental Protection Agency were considered
Table 1 Reports implicating drains as the source of outbreaks
Microorganism Reservoir Location References
SARS Dry U-traps Community, Amoy Garden, Hong Kong WHO [8]
Multidrug resistant Pseudomonas aeruginosa Faulty drains Hospital-wide and medical unit, England Breathnach et al.[7]
Carbapenem resistant Enterobacteriaceae Sink drains ICU, Melbourne, Australia Kotsanas et al. [9]
Several different fungi Drains in bathrooms
Drains in kitchen sinks
Community, Osaka, Japan Hamada et al. [10]
Pseudomonas aeruginosa Sink drains Whirlpool drains ICU at Burn hospital, Cincinnati, OH Edmonds et al.[11]
Pseudomonas aeruginosa Sink drains Medical-Surgical ICU, Chicago, IL Levin et al. [12]
Pseudomonas aeruginosa Toilets Out patients, Tübingen, Germany Döring et al. [13]
Fusarium spp. Plumbing drains 131 buildings from 8 states, US Short et al. [6]
extended-spectrum beta-lactamase-producing
(ESBL) Enterobacteriaceae
Sink drains Cardiac-Surgical ICU, France Kac et al.[14]
Pseudomonas aeruginosa Sink drains Hematology unit, Lund, Sweden Dagens Nyheter [15]
ESBL Klebsiella pneumoniae Sink drains Neurosurgical ICU, Uppsala, Sweden Starlander et al.[5]
Klebsiella pneumonia Carbapenem resistant Sink drains ICU, Sørlandet, Norway Tofteland et al. [16]
Pseudomonas aeruginosa Drains ICU, Edinburgh, UK Gillespie et al. [17]
ESBL Enterobacteriaceae Sink drains ICU, Tours, France Roux et al. [18]
Carbapenem-resistant P. aeruginosa Unsealed drain Urology ward, Barcelona, Spain Peña et al. [19]
P. aeruginosa with unusual antibiogram Drains Neurosurgery ICU, Clichy, France Bert et al. [20]
ESBL Klebsiella oxytoca Sink drains Hospital, Toronto, Canada Lowe et al. [21]
Foot Mouth Disease virus Leaking drains Community, Pirbright, UK HSE [22]
P. aeruginosa Grooved drainage design Haemotology, Singapore Ling and How [23]
Carbapenem resistant Klebsiella oxytoca Drainpipes, traps ICU, Spain Vergeres -Lopez et al. [24]
Blom Archives of Public Health (2015) 73:8 Page 2 of 8
to be relevant to assess the risk to be exposed to sewage.
The search outcome, 71 references, is summarized in this
review and describes aspects that support the finding that
drainage systems if not properly installed or designed and
maintained shall be considered as hazardous that may
cause infections and emergence of pathogens armed with
additional resistance and virulence as well as other diseases
e.g. allergies against mold.
Results and discussion
Wastewater as a source of infection
Developing countries
In particular developing countries and to some extent also
developed countries, rural areas predominantly, sanitation
is inadequate resulting in diseases such as infections [2]. It
is estimated that there are over 4 billion diarrheal cases
per year resulting in 2.2 million deaths [2]. The major
cause is exposure to excreta and wastewater where Vibrio
cholerae and Salmonella typhi are notable causes of diar-
rheal diseases [25,26]. Interventions focusing on sanitation
has shown to reduce the percentage in diarrheal morbidity
with 36% [27]. Other benefits with improved sanitation
are economic and environmental gains [28]. In numbers,
the return of investment is huge. Every US$1 invested on
sanitation brings a $5.50 return by keeping people healthy
and productive. In comparison, poor sanitation, costs
countries between 0.5 and 7.2% of their gross domestic
product (GDP) [28]. The potential savings and need for
better quality in life has resulted in e.g. the UN-Water
wastewater task force involving different stakeholders
working to improve sanitation [29].
Working environment at wastewater treatment plants
In excreta disposal there is a high load of microorgan-
isms such as viruses, bacteria, fungi, and protozoa that
could cause infections [30,31]. Based on the study of
Korzeniewska and Harnisz, the load of enteric bacteria is
probably underestimated due to insufficient detection
methods [32]. Furthermore, it has been shown that both
air and water are contaminated by bacteria in the sewage
at Wastewater Treatment Plants (WWTP) jeopardizing
the health of both plant workers and surrounding
population [32]. Clearly human excreta must be managed
in a safe way to minimize the risk of exposure to microbes
of clinical significance. This condition is further realized
in regulations and guidance documents by e.g. the Centers
for Disease Control and Prevention (CDC), Health Safety
Executive (HSE) in UK, and Environmental Protection
Agencies (EPA) to assure safe working environment for
workers exposed to excreta disposal [33-35]. Sadly, despite
abolition of manual scavenging in India, about 1.2 million
scavengers work as sanitary workers and face numerous
health hazards among them infections [36].
Food Industry
In food industry, food safety is essential and regulated.
Regulations have been spawn from risk impact assessments
(RIA) and cost-benefit analysis [37]. The production is run
applying two different systems, hazard analysis critical con-
trol points (HACCP) and Good Manufacturing Practice
(GMP) intended to assure the safety of food. A major focus
is on the reduction of microbes. Noteworthy, is the
architectural demands of GMP. GMP focus on e.g. that the
facilities must be built and the work must be done so that
the risk of contamination is minimized and the quality of
the product can be assured. In practice, sinks must be
placed strategically to ease the drainage of water during
cleaning, and in clean rooms or sterile rooms with the
highest clean air requirements, sinks or floor drains are not
allowed. Pipes must be made of certain materials and their
dimensions must differ from those drainage design
requirements in ordinary buildings. Floor drains should be
kept to a minimum and must be free from debris, giving
off no offensive odors. In addition, all building drains must
be cleaned and sanitized on a regular basis. Their design
must prevent the possibility of backflow. Open channels
should be easy to clean and disinfect. These drains must
always be filled with water as a physical barrier and their
covers must remain intact. Maintenance must be recorded
and continuously monitored. Furthermore, it is essential
and mandatory to continuously monitor and include
environmental sampling. In the food industry, it has been
suggested that if one organism is found in the preparation
environment, then there is a 70% chance of it getting into
the food (Chris Griffith at IAFP Rome 2007). If this
principle holds, then the risk of cross-contamination from
the buildings drainage systems to other surfaces and/or
individuals at hospitals is indeed high. However, GMP
systems are not applied in healthcare. Although, HACCP
has been evaluated for its applicability to reduce infections
but only a handful studies have been found [38]. Thus,
practices or maintenance programs considering the
Wastewater as a source of emerging novel pathogens
Sewage sludge can end up on landfills but this is problem-
atic since the leakages from the landfill may reach the
groundwater [39]. WWTP then offer better management
of the sewage since it has to go through different
stabilization treatments in order to produce safe sewage
sludge [40]. However, WWTPs are focusing mainly on sta-
bilizing organic residues and heavy metals while microbes
are neglected. Sewage sludge commonly contains high
load of microbes that are able to infect both humans and
animals but currently ways of accurate detection and
treatment are lacking [32,41]. Detection with conventional
plate count technique is most likely not working since
bacteria can exist in viable but non-culturable stage and
Blom Archives of Public Health (2015) 73:8 Page 3 of 8
hence the load will be underestimated [42]. These reser-
voirs of microbes could then go undetected and be spread
to the environment and infect crops, animals, and humans
[43]. Yet another spread from the environment to the
microbiome can be genetic information coding for resist-
ance and virulence [44-46]. This mode of genetic transfer
is most likely to have occurred in the case of the rise of
the German isolate of Escherichia coli (E. coli) that was
found to have two different mechanisms of virulence [47].
This isolate belonged to enteroaggregative E. coli (EAEC)
carrying virulence factors on a plasmid (a mobile genetic
material) and it obtained the shiga toxin gene carried on a
phage (a mobile genetic element) from a shiga toxin
producing E. coli (STEC). It caused unpredictable novel
clinical manifestations in a severe outbreak in Germany
2011 with nearly 7,000 reported cases and 18 deaths due
to gastroenteritis and 35 deaths due to hemolytic uremic
syndrome [47]. The ease by that bacteria can share genetic
information on mobile elements and the knowledge that
genes coding for resistance is coded by mobile genetic
elements probably will present further unwanted surprises
[48]. The fear of creation of multi-resistant bacteria is
enforced by the fact that antibiotics are discharged from
manufacturers and hospitals and will stress the bacteria in
the sewage or environment to develop and disseminate
resistance [46,49,50]. Evidence was presented at the 51st
Interscience Conference on Antimicrobial Agents and
Chemotherapy that hospital sewage is breeding ground
for genetic exchange of resistance between bacteria in the
environment and clinical isolates [51]. Furthermore, it was
recently proven that resistance cassettes against five
classes of antibiotics (β-lactams, aminoglycosides, ampheni-
cols, sulfonamides, and tetracyclines) had a perfect genetic
match in a clinical relevant bacteria and an environmental
bacteria [52]. This study explained the mechanism of lateral
spread but also how antibiotic resistance disseminate and
can have clinical implications. In the era of increased anti-
biotic resistance and less available effective therapies, it is
increasingly difficult to treat infections. Still with effective
antibiotics, infections remain a primary cause of morbidity
and mortality in the developed world [53]. Predictions say
that unless immediate and consorted actions are taken we
will face mortality rate like the pre-antibiotic era. In relation
to this dark prediction, the WHO has stated that:
Antibiotic resistance is one of the greatest threats to
global health security extending far beyond the human
health sector. The future looks dark also in respect to the
possibility of finding the substance that will kill and not
provoke resistance [54]. Therefore the return of in-
vestment to develop novel antibiotics is judged not
worth the effort, hence few drugs are in the pipeline
[54,55]. Instead, focus has been directed to preventive
measurements. Infection prevention programs have
been enforced by the World Health Organization
(WHO), European Commission and the US, and national
governments [56-59].
Drains as source of infection
The clinical impact of drains as reservoirs of microor-
ganisms has not yet been fully explored although it is
widely established that human excretions such as faeces,
urine, oral-nasal aerosols, and skin flakes will carry
microbial burden consisting of bacteria and/or virus. For
instance, there are 120 different viruses in human faeces
[43]. It is also reported that patient flora can be detected
in sinks and building drains [10,12,60]. In a new long-
stay hospital, it was discovered that identical strains were
found in the sinks as well as in the admitted patients
[60]. The major correlating strains were pathogens such
as the Escherichia coli, Klebsiella,Pseudomonas and
Acinetobacter species, all being gram-negative bacteria,
with higher correlation to strains isolated from the
throats and intestines of patients. Actually, the major
reservoir of multi-drug resistant Gram-negative bacilli is
the gut of man and animals. At hospitals, discharge of
antibiotics are also high [49]. Clearly, drains are reser-
voirs for microbes and antibiotic residues. It is also clear
that microbes in drains and pipes adheres to the surfaces
of drains and draining pipes as microbial biofilms, creating
a complex ecosystem of different microbes that are fed by
organic and inorganic matters [61]. Hota et al.elegantly
showedthepresenceofPseudomonas aeruginosa (P.
aeruginosa) biofilm in drainage systems and their role
in the propagation of an outbreak [61]. It is also
known that bacteria such as S. aureus promote the
transfer of antibiotic resistance to other bacteria when
present in biofilm [62]. Certainly, drains seem to act
as cradles to the emergence of bacteria armed with
abilities to resist multiple antibiotics. The development of
resistance is probably enhanced at hospitals due to that
more bacteria and more antibiotics are flushed down the
drains due to the very nature of hospitals constantly
caring for numerous different patients that are ill and
treated with antibiotics. Thus, biofilm in building drains,
not properly maintained, have the potential of spreading
even more resistant bacteria. This was indicated in the
extended non-frequent outbreak of Carbapenem resistant
Klebsiella pneumonia (KPC) at an ICU [16]. The source
of transmission was found to be drains that was detected
by molecular profiling to be the only source to harbor
KPC, persistently. Outbreak with P. aeruginosa, revealed
that patients were not colonized on admittance, but ac-
quired a multi-resistant P. aeruginosa during hospitalization
[17]. By running antibiogram and molecular profiling,
drains were found to be the only source. Therefore these
reservoirs are crucial to control. Maintenance of proper
sanitation must then be guarded where seepage and back-
flow never should occur. However, it seems that the
Blom Archives of Public Health (2015) 73:8 Page 4 of 8
management of maintenance is more difficult in practice
than in theory. The difficulty of eradicating antibiotic resist-
ant bacteria from sink drains at an intensive care unit
(ICU) was recently reported [9]. Several different cleaning
methods were tried including hypochlorite, mechanical,
and pressurized steam at a temperature of 170°C. However,
none of these methods worked. This highlights the need for
physical barriers such as water seals for drains that prevent
the exposure to microbes in the drains and a way to control
the integrity of the barrier.
The impact of malfunctioning plumbing
The malfunctioning plumbing was recognized as a prob-
lem already during the cholera outbreak in London by J.
Snow in the 19
century [63]. Later in 1907, it was shown
in a sham study that malfunctioning plumbing created
aerosols with microorganisms that could be transmitted
to humans both indirectly through environmental surfaces
and directly through aerosols and cause disease [64].
Sham studies, also in present time support earlier findings
and stress the importance of a physical barrier by a water
seal between the drainage systems and surroundings [65].
The creation of aerosols has been shown to occur when
the plumbing is not correctly designed or if there are
leakages, stops or by dried U-traps. Also, aerosols can be
created upon flushing the toilet or in situations when
water is poured from taps to sinks and drains [66,67]. As
shown in the SARS outbreak at Amoy Gardens, aerosols
can enter the ventilation system and be spread to all the
other connected rooms igniting a fearsome spread [67].
The outbreak at Amoy Gardens highlights the need for
good maintenance practices and water safety programs
with recommended actions [68]. In the event of backflow
or flooding from the drainage systems of wastewater into
the building, prompt actions must be taken to protect
health and property [31]. Among public health profes-
sionals, it is well known that if wastewater leaks to
structures and furnishing harmful substances such as
gases and pathogenic microorganisms can enter as
well as increased humidity that can promote environ-
mental microorganisms to multiply and cause diseases
and mold-associated allergies [31]. Therefore, it is essen-
tial that the properties are restored to a dry state as
quickly as possible [31]. In recommended guidelines by
EPA in the US, these highlight the increased safety risks
due to the high threat of infection, in the event of sewage
backflow into buildings [31]. Consequences of malfunc-
tioning plumbing can indeed cause outbreaks [7]. In one
outbreak in London, 85 patients became infected during
2005 and 2011, with overall mortality at 40%, but for
patients with sepsis, mortality was 78%. Yet another
outbreak occurred in Southern England with four
cases and no deaths. Both outbreaks were caused by
multidrug-resistant P. aeruginosa. There had been 391
notifications of blockages in the wastewater system at
the hospitals each year. Blockages had been due to
patient wipes and paper towels causing backflow to
toilets and showers, leakages, etc. near clinical areas
[7]. It was first after re-plumbing, replacing toilet bowls,
and etc., the infection rates were notably reduced. The
authors stressed the importance of hospital design and
engineering in controlling and preventing infection, a
factor that highlights the need for engagement from the
clinical staff, engineers, and janitors. Also, to consider,
these outbreaks were identified due to the unusual
antibiogram of organisms and could thus be linked to the
hospital wastewater systems. Clearly, hospital wastewater
system could be a source of many cases of infection with
different bacteria. Breathnach et al. concluded: However,
unless the organisms are distinctive in some way, such as
being multiply resistant, or several cases with the same
species linked in time or place, it is likely that the source
of many such infections will remain unrecognized[7].
Maintenance of sanitation is essential
Facts point at that sanitation is essential to maintain, to
reduce the risk of infection [1]. In a press release from
WHO it stated that in absence of proper maintenance
and without consistent monitoring, reviewing, enforcing
and updating of building standards and practices,
inadequate plumbing and sewage systems could continue
to enhance the potential of SARS and some other diseases
to spread [4]. Numerous cases from both developing
and developed countries describe outbreaks caused by
faulty sanitation [2] (Table 1). The problem might be
that once sanitation facilities are installed the general
opinion seems to regard it as a self-sustaining system
that is safe. Furthermore, it is easily forgotten since the
drainage systems is out of sight. Thus drainage systems
are neglected as potential reservoirs of transmission of
microorganisms. It is when they cease to function
adequately because of e.g. leakages or blockages that the
threats to health becomes a reality and inspections
followed by reparations or even total exchange of drainage
systems are required [31,69]. The awareness about the
impact of inadequate sanitation seems poor. The illnesses
society, and nations [31].
Research need
Interdisciplinary work is needed in order to establish
guidelines for healthy sanitation in buildings focusing
on the clinical need for infection control supported
by architectural design and maintenance practices. To
accomplish the task, three aspects important for infection
reduction must be evaluated. 1) Detection of pathogen
containing aerosols and surface contaminants should be
done and further analyzed by molecular profiling and
Blom Archives of Public Health (2015) 73:8 Page 5 of 8
antibiograms in order to trace outbreak related pathogens.
2) Current architectural designs should be evaluated if
constructed from an infection reduction perspective. 3)
Also, the different maintenance practices should be evalu-
ated and explored how to optimize. Possibly, the GMP
guideline in food industry and their demands from an
infection reduction perspective could be a good start to
learn from. Also, the building and facility sectors should
be involved to develop what actions are required to main-
tain a safe sanitation system and with what detection
methods maintenance can be surveyed. One detection
method that could meet the demands for accurate moni-
toring of the status in the drainage systems is a technique
based on sonar technology, developed by Gormley et al.
[70]. The need for guidance is especially urgent within
healthcare owing to that at hospitals the majority are
patients that are sick with less fit immune system and
therefore more receptive to infections and thus in need of
antibiotics that are effective.
Further research is needed to explore how aerosols
produced with or without faulty drainage systems can be
disseminated by existing ventilation system and cause
disease. In the case with the SARS outbreak, it was
clearly shown that the spread of the virus containing
aerosols created from the drains was facilitated by the
ventilation system. It was further proven in a sham study
that aerosols were created and spread by the airflow
upon flushing a toilet [67]. Spread of pathogens from
wastewater via the drainage systems and out where no
physical barrier exist has also been proven in yet other
sham studies [71] evoking further issues such as what
are the consequences of letting out gases and aerosols
through the roof, possibly next to a ventilation inlet, or
if there is a leakage along the drainage systems within
the building [71]? Leakage or seepage shall be consid-
ered and its consequences analyzed. One possible effect
could be that humidity is increased thus promoting
microbial growth of for e.g. fungi risking mold in the
building and allergies to the inhabitants. The impact of
microscopic sized leakage is also of interest to study if
these would allow microorganisms being microscopically
small; virus being 0.1 μm, bacteria around 1 to 10 μm,
and fungi around 10 μm big, to leak. Results may show
that it is essential that drainage systems must be
completely tight and intact where openings have
physical barriers.
Despite good sanitation, problems arise when the sanita-
tion system is not working properly in case of e.g. leak-
age and backflow caused by blockages or dried out traps.
It is beyond proof that wastewater, sewages, or drains
act as cradles for emerging new microorganisms with
increasing ability to resist antibiotics and possibly armed
with virulence factors obtained from other encountered
species [47,50,51]. The cradles consist of microbial
biofilm, where transfer of genes coding resistance and
virulence is promoted [47,62]. The pressure for selection
of resistant microbes is probably higher in healthcare
settings due to the turnover of many sick patients
shedding along with administered antibiotics down the
drains. Drains have been reported to be the source of
several outbreaks. However, outbreaks are not often
linked to the environment unless the outbreak isolate
possesses an unusual multi-resistant profile [7]. The
threat of mortality rate equaling the pre-antibiotic era is
immediate and not for future. If no efficient antibiotics,
current infections cant be treated and sensitive inter-
ventions will not be possible to pursue. Therefore, pre-
ventive actions are urgent and must be taken to reduce
infections causing us to focus on the fundamental need
for a safe and maintained sanitation system.
Competing interests
Dr. Kristina Blom is a consultant to many different companies and has for
this study been sponsored by Dyteqta Ltd.
Received: 13 October 2014 Accepted: 2 December 2014
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Blom Archives of Public Health (2015) 73:8 Page 8 of 8
... Sanitation refers to public health conditions related to clean drinking water and adequate treatment and disposal of human excreta and sewage (Blom, 2015;Fagbemiro et al., 2016). Preventing human contact with feces is part of sanitation, as is hand washing with soap (Cairncross and Valdmanis, 2006;Freeman et al., 2017). ...
Full-text available
This study examined the water-sanitation practices and health risk perceptions of women in selected rural communities in Abuja, Nigeria by assessing the knowledge of women in the sanitation practices adopted during collection, and preservation of potable water. Descriptive cross-sectional research design was employed and one hundred (100) questionnaires were administered. Eighty�one (81) were retrieved, deemed useful and consequently used for data analysis. The study found that women in the study area are fairly knowledgeable about sanitation practices. Sanitation practices such as washing of hands with soap and water before handling potable water, cleaning buckets, kegs and drums regularly, basic maintenance of hygiene around the water collection and preservation point were observed. The findings revealed moderate health risk perception concerning the consequences of poor water and sanitation practices, inadequate hygiene education, leading to inadequate environmental sanitation. Inadequate maintenance of facilities at water sources, restricted access to pipe-borne water, lack of funding for community sanitation officers, and shortage of community health workers, are the immediate problems faced in the collection and preservation of potable water in the study area.
... Given the drainage system as a reservoir for not only SARS-CoV-2 but also other transmissible human pathogens [55][56][57], the design and maintenance of sanitary plumbing in high-rise buildings require specific attention and professional guidance [58]. However, current drainage design guidelines for high-rise buildings are the same as traditional low-rise houses. ...
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COVID-19 outbreaks in high-rise buildings suggested the transmission route of fecal-aerosol-inhalation due to the involvement of viral aerosols in sewer stacks. The vertical transmission is likely due to the failure of water traps that allow viral aerosols to spread through sewer stacks. This process can be further facilitated by chimney effect in vent stack, extract ventilation in bathrooms, or wind-induced air pressure fluctuations. To eliminate the risk of such vertical disease spread, installation of protective devices is highly encouraged in high-rise buildings. Although the mechanism of vertical pathogen spread through drainage pipeline has been illustrated by tracer gas or microbial experiments and numerical modeling, more research is needed to support the update of regulatory and design standards for sewerage facilities.
... Thus, restricting the spread of AMR is particularly challenging in impoverished settings where vulnerability to environmental hazards is highest [20,21]. Even in urban areas that can rely on centralized waste-water treatment facilities and drinking-water plants, there have been several reports of sanitation-related outbreaks from malfunctioning and outdated water management systems [22]. Furthermore, there are limited data on the ability of water treatment technologies available in low-and middleincome countries for removing antibiotic residues and antibiotic-resistant genes (ARG). ...
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Antimicrobial resistance (AMR) is one of the top 10 global public health threats facing humanity, especially in low-resource settings, and requires an interdisciplinary response across academia, government, countries, and societies. If unchecked, AMR will hamper progress towards reaching the United Nations Sustainable Development Goals (SDGs), including ending poverty and hunger, promoting healthy lives and well-being, and achieving sustained economic growth. There are many global initiatives to curb the effects of AMR, but significant gaps remain. New ways of thinking and operating in the context of the SDGs are essential to making progress. In this entry, we define the next generation of the AMR research network, its composition, and strategic activities that can help mitigate the threats due to AMR at the local, regional, and global levels. This is supported by a review of recent literature and bibliometric and network analyses to examine the current and future state of AMR research networks for global health and sustainable development.
... Nueber was the first man to ever use animal bones in the development of drains, he used decalcified ox bones though it had an advantage of absorption rate of 6 -20 days, however, it did create a huge controversy and objection among the Hindu population for their religious sentiments. 11 It was further developed by Beyer who used aorta of oxen, which had similar objections and got rejected. ...
... Under these circumstances, measures including strict precautions, adequate protective devices, and infection control training should be implemented for all hospital workers, especially assistants and cleaners who handle the excreta of these patients and toilet disinfection. Moreover, public education on toilet hygiene, such as closing the toilet lid before flushing, avoiding low water levels of sewage U-traps, and reiterating the importance of hand hygiene, may minimize the risk of community outbreaks [23]. Adequate infection control training for all medical staff and provision of personal protection equipment such as masks, face shields, goggles, and protective clothes are recommended by the WHO [24]. ...
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As a city famous for tourism, the public healthcare system of Macau SAR has been under great pressure during the outbreak of the Coronavirus Disease 2019 (COVID-19). In this study, we report clinical and microbiological features of ten COVID-19 patients enrolled in the Centro Hospitalar Conde de São Januário (CHCSJ) between January 21 to February 16, 2020. Clinical samples from all patients including nasopharyngeal swab (NPS)/sputum, urine, and feces were collected for serial virus RNA testing by standard qRT-PCR assay. In total, seven were imported cases and three were local cases. The median duration from Macau arrival to admission in imported cases was 3 days. Four patients required oxygen therapy but none of them needed machinal ventilation. No fatal cases were noted. The most common symptoms were fever (80%) and diarrhea (80%). In the "Severe" group, there was significantly more elderly patients (p=0.045), higher lactate dehydrogenase levels (p=0.002), and elevated C-Reactive protein levels compared to the "Mild to Moderate" group (p<0.001). There were positive SARS-CoV-2 RNA signals in all patients' NPS and stool specimens but negative in all urine specimens. Based on our data on SARS-CoV-2 RNA shedding in stool and the possibility of a lag in viral detection in NPS specimens, the assessment of both fecal and respiratory specimen is recommended to enhance diagnostic sensitivity, and also to aid discharge decision before the role of viral RNA shedding in stool is clarified.
... Despite lower E. coli concentrations in neighborhoods with high (sometimes > 90%) sanitation coverage, open drains in all neighborhoods-even those with almost 100% coverage of sanitation facilities at households-had concentrations high enough to constitute a public health hazard, especially given the prevalence of open drainage. Mean E. coli levels of 4.1-5.6 log 10 CFU/100 mL are lower than in drains of uniformly low-income neighborhoods of Accra (8.5 log 10 CFU/100 mL) (Berendes et al., 2018a), but these drains may still carry large pathogen loads from human and animal sources (Blom, 2015). For context, the lowest concentrations of E. coli observed in open drains in this study were still 10-100 fold greater than USEPA regulations for wastewater discharge into recreational water bodies that humans contact (EPA, 2012). ...
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Alongside efforts to improve safe management of feces along the entire sanitation chain, including after the toilet, global sanitation efforts are focusing on universal access 'basic' services: onsite facilities that safely contain excreta away from human contact. Although fecal sludge management is improving in urban areas, open drains remain a common fate for feces in these often densely-populated neighborhoods in low-income countries. To-date, it is unclear to what extent complete coverage of onsite sanitation reduces fecal contamination in the urban environment and how fecal contamination varies within urban drains across neighborhoods by sanitation status within a city. We assessed how neighborhood levels of environmental fecal contamination (via spatially-representative sampling of open drains for E. coli) varied across four neighborhoods with varying income, type and coverage of household sanitation facilities, and population density in Accra, Ghana. Neighborhoods with very high sanitation coverage (≥89%) still had high (>4 log10 CFU/100 mL) E. coli concentrations in drains. Between-neighborhood variation in E. coli levels among the high coverage neighborhoods was significant: drain concentrations in neighborhoods with 93% and 89% coverage (4.7 (95% CI: 4.5, 4.9) & 4.9 (95% CI: 4.5, 5.3) log10 CFU/100 mL, respectively) were higher than in the neighborhood with 97% coverage (4.1 log10 CFU/100 mL, 95% CI: 3.8, 4.4 log10 CFU/100 mL). Compared with the highest coverage neighborhood, the neighborhood with lowest coverage (48%) also had higher E. coli concentrations (5.6 log10 CFU/100 mL, 95% CI: 5.3, 5.9 log10 CFU/100 mL). Although fecal contamination in open drains appeared lower in neighborhoods with higher onsite sanitation coverage (and vice versa), other factors (e.g. fecal sludge management, animals, population density) may affect drain concentrations. These results underscore that neighborhood-level onsite sanitation improvements alone may not sufficiently reduce fecal hazards to public health from open drains. These findings supporting the need for integrated, city-level fecal sludge management alongside multifaceted interventions to reduce fecal contamination levels and human exposure.
... The floodwater runs off into storm sewers and ultimately into surface water, and during heavy rainfall, the contaminated water returns to the environment and contaminates the soil [45]. Poor drainage systems, improper child feces disposal, and poor fecal sludge management likely increase the fecal contamination of the soil in low-income neighborhoods [46]. Lastly, unimproved housing infrastructure (i.e., dirt floor/walkway), poor hydraulic and physical integrity of the water distribution network (leaky flexible pipes and illegal connections), unsafe water storage, high population density, and poorly designed and constructed on-site household and community sanitation systems that do not adequately contain fecal sludge may contribute to higherlocalized fecal contamination levels in soil and water in low-income neighborhoods in Dhaka [47,48]. ...
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Rapid urbanization has led to a growing sanitation crisis in urban areas of Bangladesh and potential exposure to fecal contamination in the urban environment due to inadequate sanitation and poor fecal sludge management. Limited data are available on environmental fecal contamination associated with different exposure pathways in urban Dhaka. We conducted a cross-sectional study to explore the magnitude of fecal contamination in the environment in low-income, high-income, and transient/floating neighborhoods in urban Dhaka. Ten samples were collected from each of 10 environmental compartments in 10 different neighborhoods (4 low-income, 4 high-income and 2 transient/floating neighborhoods). These 1,000 samples were analyzed with the IDEXX-Quanti-Tray technique to determine most-probable-number (MPN) of E. coli. Samples of open drains (6.91 log10 MPN/100 mL), surface water (5.28 log10 MPN/100 mL), floodwater (4.60 log10 MPN/100 mL), produce (3.19 log10 MPN/serving), soil (2.29 log10 MPN/gram), and street food (1.79 log10 MPN/gram) had the highest mean log10 E. coli contamination compared to other samples. The contamination concentrations did not differ between low-income and high-income neighborhoods for shared latrine swabs, open drains, municipal water, produce, and street foodsamples. E. coli contamination levels were significantly higher (p
The failure of current sanitation practices requires the development of effective solutions for microbial control. Although combinations using antibiotics have been extensively studied to look for additive/synergistic effects, biocide combinations are still underexplored. This study aims to evaluate the antimicrobial effectiveness of dual biocide and triple biocide/phytochemical combinations, where phytochemicals are used as quorum sensing (QS) inhibitors. The biocides selected were benzalkonium chloride (BAC) and peracetic acid (PAA) – as commonly used biocides, and glycolic acid (GA) and glyoxal (GO) – as alternative and sustainable biocides. Curcumin (CUR) and 10-undecenoic acid (UA) were the phytochemicals selected, based on their QS inhibition properties. A checkerboard assay was used for the screening of chemical interactions based on the cell growth inhibitory effects against Bacillus cereus and Pseudomonas fluorescens. It was observed that dual biocide combinations resulted in indifference, except the PAA + GA combination, which had a potential additive effect. PAA + GA + CUR and PAA + GA + UA combinations also triggered additive effects. The antimicrobial effects of the combinations were further evaluated on the inactivation of planktonic and biofilm cells after 30 min of exposure. These experiments corroborated the checkerboard results, in which PAA + GA was the most effective combination against planktonic cells (additive/synergistic effects). The antimicrobial effects of triple combinations were species- and biocide-specific. While CUR only potentiate the antimicrobial activity of GA against B. cereus, GA + UA and PAA + GA + UA combinations promoted additional antimicrobial effects against both bacteria. Biofilms were found to be highly tolerant, with modest antimicrobial effects being observed for all the combinations tested. However, this study demonstrated that low doses of biocides can be effective in bacterial control when combining biocides with a QS inhibitor, in particular, the combination of the phytochemical UA (as a QS inhibitor) with GA and PAA.
Background: Decades of studies document an association between Gammaproteobacteria in sink drains and hospital-acquired infections, but the evidence for causality is unclear. Aim: We aimed to develop a tool to assess the quality of evidence for causality in research studies that implicate sink drains as reservoirs for hospital-acquired Gammaproteobacterial infections. Methods: We used a modified Delphi process with recruited experts in hospital epidemiology to develop this tool from a pre-existing causal assessment application. Findings: Through four rounds of feedback and revision we developed the Modified CADDIS Tool for Causality Assessment of Sink Drains as a Reservoir for Hospital-Acquired Gammaproteobacterial Infection or Colonization. In tests of tool application to published literature during development, mean percent agreement ranged 46.7 - 87.5, and the Gwet's AC1 statistic (adjusting for chance agreement) ranged .13 - 1.0 (median 68.1). Areas of disagreement were felt to result from lack of a priori knowledge of causal pathways from sink drains to patients and uncertain influence of co-interventions to prevent organism acquisition. Modifications were made until consensus was achieved that further iterations would not improve the tool. When the tool was applied to 44 articles by two independent reviewers in an ongoing systematic review, percent agreement ranged 93-98%, and the Gwet's AC1 statistic 0.91-1.0. Conclusion: The modified causality tool was useful for evaluating studies that implicate sink drains as reservoirs for hospital-acquired infections and may help guide the conduct and reporting of future research.
The drain openings of hand washbasins and sinks in hospitals represent a largely overlooked yet ubiquitous reservoir of microbial contamination that is increasingly recognized as a significant cause of patient infection, particularly with carbapenemase-producing Enterobacteriaceae. These bacteria have emerged relatively recently as a major health threat in hospitals globally against which only a very few antimicrobial agents remain active. The three main areas this chapter overviews are: the problem of microbial biofilm contamination of washbasin U-bend traps and drains in hospital hand washbasins and sinks; the associated risks of transmission of infection to patients and healthcare staff; and the approaches that have been investigated to mitigate these risks. First this chapter reviews the underlying causes of trap contamination and current evidence for cross-infection in the hospital setting. The various approaches that have been investigated to minimize infection risks from washbasin traps and drains are then discussed together with their relative advantages and disadvantages. Finally, the chapter examines the development of long-term solutions to the problem using integrated systems for automated decontamination of washbasin drains, U-bend traps, and wastewater pipework in the hospital setting.
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The reuse of treated effluent (for agriculture and as supplement for drinking water needs) is currently receiving attention as a reliable water source. This paper is aimed at reviewing the environmental and health impacts of untreated or inadequately treated wastewater effluents. The quality of wastewater effluents is responsible for the degradation of the receiving water bodies. This is because untreated or inadequately treated wastewater effluent may lead to eutrophication in receiving water bodies and also create environmental conditions that favour proliferation of waterborne pathogens of toxin-producing cyanobacteria. In extension, recreational water users and anyone else coming into contact with the infected water is at risk. Although various microorganisms play many beneficial roles in wastewater systems, a great number of them are considered to be critical factors in contributing to numerous waterborne outbreaks. Also, wastewater effluents have been shown to contain a variety of anthropogenic compounds, many of which have endocrine-disrupting properties. Since large amounts of wastewater effluents are passed through sewage treatment systems on a daily basis, there is a need to remedy and diminish the overall impacts of these effluents in receiving water bodies. In order to comply with wastewater legislations and guidelines, there is a need for adequate treatment before discharge. This can be achieved through the application of appropriate treatment processes, which will help to minimize the risks to public health and the environment. To achieve unpolluted wastewater discharge into receiving water bodies, careful planning, adequate and suitable treatment, regular monitoring and appropriate legislations are necessary.
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Background: The determinants of the spread of extended-spectrum β-lactamase-producing Escherichia coli (ESBLEC) in the community remain unclear. To evaluate its dissemination in the environment, we analyzed the ESBLEC population throughout an urban wastewater network. Methods: Samples were collected weekly, over a 10-week period, from 11 sites throughout the wastewater network of Besançon city (France). Total E. coli and ESBLEC loads were determined for each sample. As a control, we analyzed 51 clinical ESBLEC isolates collected at our hospital. We genotyped both environmental and clinical ESBLEC by pulsed-field gel electrophoresis and multilocus sequence typing and identified their blaESBL genes by sequencing. Results: The E. coli load was higher in urban wastewater than in hospital wastewater (7.5 × 10(5) vs 3.5 × 10(5) CFU/mL, respectively). ESBLEC was recovered from almost all the environmental samples and accounted for 0.3% of total E. coli in the untreated water upstream from the wastewater treatment plant (WWTP). The ESBLEC load was higher in hospital wastewater than in community wastewater (27 × 10(3) vs 0.8 × 10(3) CFU/mL, respectively). Treatment by the WWTP eliminated 98% and 94% of total E. coli and ESBLEC, respectively. The genotyping revealed considerable diversity within both environmental and clinical ESBLEC and the overrepresentation of some clonal complexes. Most of the sequence types displayed by the clinical isolates were also found in the environment. CTX-M enzymes were the most common enzymes whatever the origin of the isolates. Conclusions: The treatment at the WWTP led to the relative enrichment of ESBLEC. We estimated that >600 billion of ESBLEC are released into the river Doubs daily and the sludge produced by the WWTP, used as fertilizer, contains 2.6 × 10(5) ESBLEC per gram.
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Abstract Molecules with antibiotic properties, produced by various microbes, have been around long before mankind recognized their usefulness in preventing and treating bacterial infections. Bacteria have therefore been exposed to selection pressures from antibiotics for very long times, however, generally only on a micro-scale within the immediate vicinity of the antibiotic-producing organisms. In the twentieth century we began mass-producing antibiotics, mainly synthetic derivatives of naturally produced antibiotic molecules, but also a few entirely synthetic compounds. As a consequence, entire bacterial communities became exposed to unprecedented antibiotic selection pressures, which in turn led to the rapid resistance development we are facing today among many pathogens. We are, rightly, concerned about the direct selection pressures of antibiotics on the microbial communities that reside in or on our bodies. However, other environments, outside of our bodies, may also be exposed to antibiotics through different routes, most often unintentionally. There are concerns that increased selection pressures from antibiotics in the environment can contribute to the recruitment of resistance factors from the environmental resistome to human pathogens. This paper attempts to 1) provide a brief overview of environmental exposure routes of antibiotics, 2) provide some thoughts about our current knowledge of the associated risks for humans as well as ecosystems, and 3) indicate management options to reduce risks.
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This article constitutes an extraction of key messages originally presented in the Document: Antimicrobials and Non-Healing Wounds. Evidence, controversies and suggestions written by the European Wound Management Association (EWMA), and originally published by the Journal of Wound Care in 2013. All sections are shortened and some not included. For further details please refer to in the original document which can be downloaded via .
Background This paper describes an outbreak of Pseudomonas aeruginosa (PAE) that occurred in a haematology ward between 8 January and 24 March 2009. Four patients had healthcare-associated infections due to PAE which was recovered in the groin, blood and perianal tissue. Aim This report highlights the risks associated with the use of sinks and outlines the approach used to manage the outbreak. Methods Subsequent investigations showed that a contaminated sink drainage system represented the possible source of spread. Of a total of 21 environmental samples taken, two samples from the sink drainage system showed a similar susceptibility pattern as the patients involved in the outbreak. Four cycles of disinfection of the sink drainage systems were attempted with various modalities. Findings PAE contamination of the sink drains at the multiple grooves in the drains proved difficult to disinfect adequately, despite using several cleaning protocols. The outbreak was finally terminated following a change in the sink drainage system to one without grooves, hence preventing any further PAE colonisation. Conclusion Our experience demonstrated that the design of the sink drainage system may be a potential source of PAE contamination for an immunocompromised patient.
A potential cross-transmission route, first identified in the spread of the SARs virus in South East Asia, in which infection was spread by virus-laden aerosolised droplets entering habitable space via defective water traps is investigated. The main aim of this work was to detect norovirus in wastewater from the collection drain in a hospital Building Drainage System and attempt to trace it in the BDS vent airflow. The methodology employed polymerase chain reaction tests on waste water samples and indicated strong positives for the norovirus GII strain from the collection drain, corresponding to an outbreak in the building, confirming that the BDS is contaminated in such circumstances and poses a threat. Pathogens were not detected in the BDS vertical stack airflows; however, the methodology employed to collect samples from the airflow was considered ineffective requiring further research. An average temperature of 24.3℃ was recorded, together with an average humidity of 96.6%. This research also confirmed that inside the building drainage stack, air flow movement occurs in both the ‘up’ and ‘down’ direction. Thus, aerosolised pathogens could travel from the contaminated horizontal collection drains upwards and enter wards via defective traps or little used showers, sinks, baths and sluices.
Background Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBLE) outbreaks in intensive care units (ICUs) associated with contaminated handwashing sinks have been reported. Aim To conduct a regional study to assess whether handwashing sinks in 135 ICU patient rooms are a potential source of contamination, and to identify factors associated with an increased risk of sink contamination. Methods A multicentre study was conducted in 13 ICUs, including microbiological testing for ESBLE contamination at 185 sinks. The micro-organisms isolated were analysed using randomly amplified polymorphic DNA analysis to assess clonal spread in ICUs. Data were collected to document the use of each sink, factors that may contribute to contamination of clinical areas near to the sinks, and routine cleansing procedures for the sinks. Findings Fifty-seven sinks were contaminated (31%) with ESBLE, mostly Klebsiella (N = 33) and Enterobacter (N = 18). In two ICUs, a high contamination rate was associated with clonal spread of an epidemic isolate. Risk factors for contamination of and by handwashing sinks were frequent: 81 sinks (44%) were used for handwashing as well as the disposal of body fluids; splash risk was identified for 67 sinks (36%), among which 23 were contaminated by ESBLE. Routine sink disinfection was frequent (85%), mostly daily (75%), and involved quaternary ammonium compounds (41%) or bleach (21%). A lower sink contamination rate was significantly associated with use of the sink being restricted to handwashing and to daily sink disinfection using bleach. Conclusions In ICUs, contaminated sinks are a potential source of ESBLE in the environment of the patient, a problem that may be underestimated by ICU teams. Relatively simple measures may result in a rapid improvement of the situation, and a significant decrease of the risk of exposure of ICU patients to multiresistant Enterobacteriaceae.
We describe the epidemiology of a protracted nosocomial clonal outbreak due to multidrug-resistant IMP-8 producing Klebsiella oxytoca (MDRKO) that was finally eradicated by removing an environmental reservoir. The outbreak occurred in the ICU of a Spanish hospital from March 2009 to November 2011 and evolved over four waves. Forty-two patients were affected. First basic (active surveillance, contact precautions and reinforcement of surface cleaning) and later additional control measures (nurse cohorting and establishment of a minimum patient/nurse ratio) were implemented. Screening of ICU staff was repeatedly negative. Initial environmental cultures, including dry surfaces, were also negative. The above measures temporarily controlled cross-transmission but failed to eradicate the epidemic MDRKO strain that reappeared two weeks after the last colonized patients in waves 2 and 3 had been discharged. Therefore, an occult environmental reservoir was suspected. Samples from the drainpipes and traps of a sink were positive; removal of the sink reduced the rate number but did not stop new cases that clustered in a cubicle whose horizontal drainage system was connected with the eliminated sink. The elimination of the horizontal drainage system finally eradicated the outbreak. In conclusion, damp environmental reservoirs (mainly sink drains, traps and the horizontal drainage system) could explain why standard cross-transmission control measures failed to control the outbreak; such reservoirs should be considered even when environmental cultures of surfaces are negative.
The outbreak of severe acute respiratory syndrome (SARS), centred on Southeast Asia in 2002 and 2003, sparked fears of an uncontrollable pandemic. The outbreak at one housing complex in Hong Kong resulted in a disproportionately large number of cases with 321 people contracting the virus, resulting in 42 fatalities. This outbreak led to an investigation by World Health Organisation, which firmly laid the blame for the spread of the virus in the housing complex on defects in the building drainage and vent system. The mode of viral transmission was identified as due to airborne aerosolised particles from virus-laden excreta emanating from the drainage system. The aerosolised particles were allowed to enter the habitable space through empty water trap seals which are the main protection against such ingress in a building drainage and vent system. This research reports on the defective trap identification system developed to provide a means of testing the seal afforded by the water trap seal inbuildings. This innovative sonar-like technology incorporates a means of identifying compromised water trap seals anywhere in a building in a repeatable, non-destructive manner. While the technology has been effectively validated by a combination of laboratory investigation, site testing and numerical simulation, the rationale for the need to monitor water trap seals is less obvious to professionals operating in this field. This article addresses this issue and presents such a rationale, identifying some of the harmful pathogens which could lead to cross-contamination from person to person via the building drainage system.