Gurung Shrijana et al. / JPBMS, 2012, 19 (03)
1 Journal of Pharmaceutical and Biomedical Sciences © (JPBMS), Vol. 19, Issue 19
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JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL SCIENCES
Community acquired methicillin resistant Staphylococcus aureus in new patients
attending a government hospital in Gangtok, Sikkim
*Gurung Shrijana1,Bhutia Pema Y2 ,Pradhan Jagat2 ,Mukhopadhyay Chiranjay3, Pradhan Uttam2 .
*1M.D, Mirobiologist, 2 Consultant Microbiologist, Sir Thotub Namgyal Memorial Hospital, Gangtok, Sikkim,India.
3 Professor and HOD, Department of Microbiology, Kasturba Medical College, Manipal, Karnataka,India.
Prevalence of methicillin resistant Staphylococcus aureus (MRSA) is increasing in the community and has become an
emerging public health problem. Community acquired MRSA (CA-MRSA) strains differ from Hospital acquired MRSA (HA-
MRSA) by causing aggressive infections like furunculosis and necrotizing pneumonia in otherwise young, healthy
Aim: - This study was carried out to determine the prevalence of CA-MRSA in patients attending hospital from April 2010
till March 2011.
Materials and Methods: - 2,282 clinical samples from outpatient and hospitalized patients were screened for MRSA. CA-
MRSA were identified based on the CDC definition for community acquired infection. Antibiotic resistance pattern was
studied by using the Kirby baeur disk diffusion method. Risk factors for hospital associated infections were recorded
Results: - Of the 184 strains of S. aureus isolated, 29.3% were MRSA and 48.14% was CA-MRSA.
Conclusion:- Methicillin resistance is an increasing menace and routine screening of all isolates is necessary.
Keywords: CA-MRSA; MRSA; Staphlycoccus aurues; D test; risk factors; Gangtok.
MRSA is no longer confined to the hospital environment as
they now circulate in the community among previously
healthy patients. Prevalence of MRSA infection is
increasing in the community and it accounts for > 50% of
community acquired S aureus infections in many US
centers. These community isolates differ from HA-MRSA
in their epidemiology and spectrum of disease.
Distinguishing HA-MRSA from CA- MRSA is useful in
defining epidemiology, identifying those at risk and
choosing empirical antibiotic therapy when required. True
burden of CA-MRSA cannot be determined by phenotypic
study alone as it is the acquisition of the SCCmec IVelement
by MSSA strains in the community that given rise to the
community acquired MRSA strains  thus making it
imperative to carry out molecular study for the detection
of SCCmec IV. This study was conducted to find out the
prevalence and antibiotic profile of community acquired
MRSA in patients attending the Government Hospital.
Materials and Methods:
2,282 clinical samples for culture and antibiotic sensitivity
were obtained from 120,919 outpatients and 10,199
inpatients fulfilling the inclusion criteria from April 2010
till March 2011. Patients included in the study was based
on the Centre for Disease control definition of community
acquired MRSA [3, 4]. Samples obtained from patients in the
outpatient setting or within 48 hours of hospitalization
were considered to be community acquired and those with
the following risk factors for HA-MRSA were not included
in the study: hospitalization in the previous 12 months,
receipt of dialysis or any other invasive procedure,
residence in chronic care facility or presence of in dwelling
catheter, previous use of antibiotics and contact with
health care workers. The distribution of departments were
as follows: Outpatient department- 47.59%, Medicine ward
– 15.78%Paediatric ward – 12.40%, Orthopaedic ward-
8.41%, Surgical – 6.18%, OBG- 3.46%, cardiac ICU – 2.89%,
Neonatal ICU – 1.58%, ENT – 0.96%, Eye- 0.74%. The most
common sample processed was urine (40.98%) followed
by pus, wound aspirate and wound swabs (19.54%), blood
(9.82%), throat swabs (8.55%) and sputum (6.66%). Total
number of isolated organisms was 754. Identification of S.
aureus was based on colony morphology and biochemical
reactions like catalase, coagulase. They were screened for
Methicillin resistance by the Cephoxitin (30mcg) disk
diffusion method. For quality control Staphylococcus
aureus ATCC 33400 was used as negative control and
Staphylococcus aureus ATCC 49619 was used as positive
control. The study was conducted after ethical committee
clearance from the hospital ethical committee.
The isolates were tested for antibiotic resistance to
Gentamicin (10mcg), Ciprofloxacin (5mcg), TMP-SMX
(1.25/23.75 mcg), Doxycycline (30mcg), Teicoplanin
(15mcg) and Vancomycin (30mcg) by the Kirby-Baeur disc
diffusion method. Inducible MLSB resistance was detected
by double disc diffusion method (D test) using Clindamycin
(2mcg) and Erythromycin (15mcg) placed 15 mm apart
(edge to edge).
184 strains of Staphylococcus aureus were isolated from
754 positive bacterial cultures. 54 (29.3%) MRSA was
isolated from 29 In Patients (19 patients > 48 hours of
ISSN NO- 2230 – 7885
NLM Title: J Pharm Biomed Sci.
Gurung Shrijana et al. / JPBMS, 2012, 19 (03)
2 Journal of Pharmaceutical and Biomedical Sciences© (JPBMS), Vol. 19, Issue 19
admission, 10 patients < 48 hours of admission) and 28
outpatients. The type of infections caused by MRSA is
shown in Figure 1.
Figure 1:-Infection caused by MRSA
26 strains (48.14%) were CA-MRSA out of which 17 of the
isolates were from outpatient department (7- Orthopaedic,
5- ENT, 5- Surgery) and 9 from various wards (5- Medicine,
2 –Surgery, 2-Orthopaedic). The resistance profile of the
antibiotics tested is shown in Figure 2.
Figure 2: Antibiotic resistance profile of CA- MRSA and HA- MRSA
All isolates were sensitive to Vancomycin by the disc
diffusion method. MLSB resistance profile of CA- MRSA is
shown in Table 1. The risk factors studied for acquisition
of HA-MRSA infection are shown in Table 2. Past history of
antibiotic use was the most common risk factor for the
acquisition of HA drug resistance. In patients with CA-
MRSA isolates 11 patients had close contact with domestic
animals, poultry and cows. 21 patients had more than two
types of risk factors.
Table 1: MLSB resistance profile
resistance. (D test
positive) (Resistant to both
Sensitive to Clindamycin)
Table 2: Risk factors for MRSA infection
Previous use of antibiotics
Visit to Hospital > 1 Year
Contact with Health care Worker
Presence of Chronic Underlying
Table 3: Recent studies done in India on CA-MRSA.
Place of study Year Patient
Healthy contacts of
from rural, urban
Hand swabs from
from hostels and
adults from slum
from Oct 2006-June
Since it was first reported in 1982 several outbreaks of
infection with CA-MRSA have been reported [3, 4]. In India
burden of CA- MRSA cannot be assessed due to paucity of
studies on prevalence of CA- MRSA. In a study done in
South India 11.8%  and 1.4%  of CA pyoderma cases
were due to MRSA. Other studies from various states in
India were focused on detecting colonisers in healthy
adults and children. A few of the Indian studies are shown
in Table 2. In our study 48.14% of the MRSA isolates were
CA- MRSA which is an alarming number and can pose a
significant public health problem.
CA MRSA is susceptible to wide range of non-beta lactam
antibiotics like Tetracycline, Clindamycin and TMP-SMX. 
But we encountered high degree of resistance to TMP-SMX
(84.61%) which may be due to free access to this drug in
all the primary health care centers and district hospitals in
Clindamycin is a viable treatment option for CA-MRSA but
inducible resistance can lead to treatment failure. This
necessitates the need for D-test to be implemented in
routine clinical laboratory.
resistance was seen in 7.69% (2 isolates) of CA- MRSA
which is lower when compared to the results in two south
Indian studies 15.65%  and 48.7% .
Previous use of antibiotics as a risk factor was seen in 22
patients with beta lactam antibiotics being the most
common drug used followed by floroquinolones. Use of
ciprofloxacin and cephalosporins promote colonization
and spread of MRSA in hospitals. A retrospective study
done in Canada showed patients infected with MRSA had
history of consumption of antibiotics, particularly beta
lactam antibiotics, levofloxacin and macrolides. There
are no known mechanisms for floroquinolones to select
resistance to beta-lactam antibiotics in S. aureus but
evidence is mounting that floroquinolones exhibit some
type of influence on MRSA
floroquinolone has been associated with elimination of
MSSA strains from the nasal mucosa, which might
predispose to colonization by MRSA strains .
Domestic pets, livestock, wild birds and other animals have
recently been identified as carriers of MRSA. In the
present study we found close contact with domestic
animals to be a common association in patients with
. Increased use of
Gurung Shrijana et al. / JPBMS, 2012, 19 (03) Download full-text
3 Journal of Pharmaceutical and Biomedical Sciences© (JPBMS), Vol. 19, Issue 19
community acquired infections, with 14 patients owning
one type of livestock (Pig, Cow or Poultry) at home. The
most common antibiotic used in our state government
veterinary hospital, for an average of two years (2008-
2010) was Tetracycline (63%) in porcine, beta-lactam
antibiotics (43.44%) in bovine and TMP-SMX (45.5%) in
avian population. Live-stock are known to be reservoirs of
antibiotic resistant bacteria as antibiotics are used in them
as growth promoters, prophylactically for disease
prevention or therapeutically
infections. Humans are infected by direct contact with
these animals or through contaminated food and water.
Since animals were not tested for colonization with MRSA
we cannot regard this as a risk factor, and further extensive
study needs to be done.
Colonisation with multiple multi drug resistant organisms
in the hospitals is a known fact and thus a holistic infection
control practice is required that targets all MDR
organisms- MRSA, VRE and MDR- gram negative bacilli.
Injudicious use of antibiotics must be controlled by
formulating antibiotic prescribing policy in the hospitals.
The author expresses gratitude to Tashi Bhutia, Tenzing
Choden and Manju Neopaney who have helped with the
processing of clinical samples and storage of isolates.
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