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Aetiology of suppurative corneal ulcers in Ghana and South India, and epidemiology of fungal keratitis


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A multicentre study was carried out in Ghana and southern India to determine the aetiology of suppurative keratitis in two regions located at similar tropical latitudes. Studies of fungal keratitis from the literature were reviewed. Patients presenting at rural and urban eye units with suspected microbial keratitis were recruited to the study. Corneal ulceration was defined as loss of corneal epithelium with clinical evidence of infection with or without hypopyon. Microscopy and culture were performed on all corneal specimens obtained. 1090 patients were recruited with suspected microbial keratitis between June 1999 and May 2001. Overall the principal causative micro-organisms in both regions were filamentous fungi (42%): Fusarium species and Aspergillus species were the commonest fungal isolates. Pseudomonas species were most frequently isolated from cases of bacterial keratitis in Ghana but in India the commonest bacterial isolates were streptococci. Infections of the cornea due to filamentous fungi are a frequent cause of corneal damage in developing countries in the tropics and are difficult to treat. Microscopy is an essential tool in the diagnosis of these infections. A knowledge of the "local" aetiology within a region is of value in the management of suppurative keratitis in the event that microscopy cannot be performed.
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Aetiology of suppurative corneal ulcers in Ghana and
south India, and epidemiology of fungal keratitis
A K Leck, P A Thomas, M Hagan, J Kaliamurthy, E Ackuaku, M John, M J Newman,
F S Codjoe, J A Opintan, C M Kalavathy, V Essuman,CANJesudasan, G J Johnson
Br J Ophthalmol
Background: A multicentre study was carried out in Ghana and southern India to determine the aeti-
ology of suppurative keratitis in two regions located at similar tropical latitudes. Studies of fungal kera-
titis from the literature were reviewed.
Methods: Patients presenting at rural and urban eye units with suspected microbial keratitis were
recruited to the study. Corneal ulceration was defined as loss of corneal epithelium with clinical
evidence of infection with or without hypopyon. Microscopy and culture were performed on all corneal
specimens obtained.
Results: 1090 patients were recruited with suspected microbial keratitis between June 1999 and May
2001. Overall the principal causative micro-organisms in both regions were filamentous fungi (42%):
species and
species were the commonest fungal isolates.
were most frequently isolated from cases of bacterial keratitis in Ghana but in India the commonest
bacterial isolates were streptococci
Conclusion: Infections of the cornea due to filamentous fungi are a frequent cause of corneal damage
in developing countries in the tropics and are difficult to treat. Microscopy is an essential tool in the
diagnosis of these infections. A knowledge of the “local” aetiology within a region is of value in the
management of suppurative keratitis in the event that microscopy cannot be performed.
car ring of the cornea as a result of suppurative keratitis is
an important cause of preventable blindness. In some
developing countries in the tropics, corneal infections are
the second commonest cause of blindness after unoperated
Suppurative cor neal ulcers may be caused by
bacteria, fungi, and protozoa. However, within the tropics, as
many as two thirds of ulcers may be due to filamentous fungi.
This type of ulceration is commonly associated with ocular
Untreated, suppurative keratitis may lead to opacification
and, ultimately, to perforation of the cornea. The associated
morbidity is the result of several factors and is directly affected
by difficulties in patient management because of a lack of
diagnostic facilities and appropriate treatment. Specific treat-
ment requires prompt and accurate identification of the
causative micro-organisms.
Within the setting of rural eye
hospitals in the tropics laboratory facilities are rare and diag-
nosis is based on clinical characteristics. As a direct result of
this, treatment is often empirical.
The microbial causes of suppurative keratitis vary consider-
ably between continents and countries and also within coun-
tries. It is essential to determine the local aetiology within a
given region when planning a corneal ulcer management
strategy. Several studies have investigated the epidemiology of
cor neal ulceration, causative micro-organisms, and effective
treatments, particularly in the Indian subcontinent. However
there is a paucity of infor mation in the literature with regard
to the experience in African countries.
6–8 11–14
The following study was conducted at hospitals in Ghana
and India to compare the aetiology of suppurative keratitis in
two countries, in different continents, at similar tropical
latitudes. The aims of this investigation were to improve facili-
ties for laboratory diagnosis, to determine the predominant
causative micro-organisms, to identify the most suitable
treatments, and encourage rapid referral of patients.
A prospective study of suppurative keratitis was conducted in
Ghana and southern India between June 1999 and May 2001.
Patients were recruited at the eye unit of Korle Bu Teaching
Hospital in Accra, Ghana, and also at two rural hospitals in
Agogo (Ashanti region) and Bawku (Upper East region). In
India, patients who presented with suppurative keratitis at
two r ural “taluk” hospitals in the Tiruchirapalli district of the
souther n state of Tamil Nadu were included in the study in
addition to patients from the main study centre, Joseph Eye
Hospital (JEH) base hospital.
All patients presenting with suspected suppurative keratitis
were included in the study. Corneal ulceration was defined as
loss of corneal epithelium with underlying stromal infiltrate
and suppuration associated with signs of inflammation, with
or without hypopyon.
Patients with suspected or confirmed
viral keratitis were excluded from the study. Patient consent
was mandatory for inclusion in the study.
Clinical examination and laboratory investigation
Each patient was examined at the slit lamp; clinical features
were noted and a drawing made for patient records. A corneal
scrape was performed by an ophthalmologist using a sterile 21
gauge needle, or blunt Kimura spatula, following the instilla-
tion of local anaesthetic (amethocaine hydrochloride 0.5%,
without preservative). In India, lignocaine (lidocaine) 4% was
routinely administered, anaesthetic without preservative was
sometimes used. If a patient was taking antibiotics at the time
of presentation to the clinic treatment was stopped and inves-
tigations were delayed for 24 hours.
Cor neal material obtained from scraping the ulcer was
smeared onto two slides which were stained with Gram stain
and lactophenol cotton blue mountant for microscopic exam-
ination. Material was inoculated directly onto 5% sheep’s
blood agar, Sabouraud glucose agar, and into Sabouraud
broth. In India, inhibitory mould agar (IMA) was substituted
Series editors: W V Good
and S Ruit
See end of article for
authors’ affiliations
Correspondence to:
Dr Astrid K Leck,
Department of Infectious
and Tropical Diseases,
Clinical Research Unit,
London School of Hygiene
and Tropical Medicine,
Keppel Street, London
Accepted for publication
19 July 2002
1211 on November 11, 2011 - Published by bjo.bmj.comDownloaded from
for Sabouraud glucose agar, as was routine practice of the
laboratory. At the tertiary centres, if there was sufficient
cor neal material, additional culture media were inoculated
(brain heart infusion (BHI) broth, chocolate agar, and cysteine
tryptone agar). Blood agar plates, cystine tryptone agar, and
BHI broth were incubated at 37°C. Sabouraud glucose agar
plates, Sabouraud broth, and IMA plates were incubated at
27°C. A non-nutrient agar plate was inoculated if Acan-
thamoeba keratitis was suspected and an additional slide was
prepared for microscopy.
Bacteria were further identified using routine biochemical
identification tests and selectiv e media. Identification of fungi
was carried out in London and at the Mycology Reference
Laboratory, Bristol, in addition to the overseas centres. Filamen-
tous fungi were identified according to the macroscopic appear-
ance of cultures on Sabouraud glucose, potato dextrose and
cornmeal agars, and microscopic appearance of conidia and
spore bearing structures. Yeasts were identified to species level
using the germ tube test (incubation for 1.5 hours, at 37ºC, in
horse serum), Auxacolor and API kits (Bio Mérieux).
Microbial cultures w ere considered to be significant if growth
of the same organism could be demonstrated on two or more
solid phase cultures. Similarly, if there was semiconfluent
growth at the site of inoculation or growth on one solid medium
consistent with microscopy (that is, appropriate staining and
morphology with Gram stain); or semiconfluent growth at the
site of inoculation on one solid medium (if bacteria); or growth
of the same organism on repeated scraping.
If, by micros-
copy, hyphae were observed in corneal tissue, but failed to grow
in culture, the causative organism was reported as fungal.
A total of 1090 patients presenting with suppurative keratitis
were enrolled in the study; 290 in Ghana and 800 in India. One
patient from Ghana and one patient from India presented
with bilateral infection. Fungi were identified as the dominant
causative agent of infection (including mixed infections): 44%
in southern India and 37.6% in Ghana. Bacteria were isolated
from 29.3% of cases in south India and 13.8% in Ghana (Table
1). In each case of mixed infection a single bacterial species
was associated with a single fungal species. This study
revealed a higher percentage of “mixed” infections in India
than Ghana: 5.5% versus 1.4%.
Seven patients presented with suppurative keratitis due to
infection with Acanthamoeba species in south India. The first
reported case of Acanthamoeba keratitis in Ghana was
diagnosed during this study (BJO, accepted for publication).
None of these patients were contact lens wearers.
In India 249 (31%) cases had no definitive laboratory diag-
nosis; Gram positive cocci were reported from the microscopy
in 80% (200/249) of these cases; however, cultures were nega-
tive. It was not possible to determine the aetiological agent of
144 (50%) corneal ulcer cases in Ghana (Table 1). Microscopy
and culture results were negative in 60% (87/144) of cases.
Scanty bacteria were seen in 14% (24) of Gram stained
smears. Of the remaining 33 cases which were microscopy
negative, filamentous fung i were isolated in culture from 51%
cases and bacteria from 49% cases but growth was not consid-
ered to be significant, using the criteria stated (see Materials
and methods).
Pseudomonas species were the commonest bacterial isolates
from corneal ulcers in Ghana (52.5%); P aeruginosa being the
commonest reported species. Streptococci (20%) and
staphylococci (10%) were commonly associated with corneal
infection (Table 2). In India streptococci accounted for 46.8%
Table 1 Aetiology of corneal ulcers
Type of micro-organism
India Ghana
No % No %
Definite bacterial 191 23.9 36 12.4
Definite fungal 309 38.6 105 36.2
Definite mixed 44 5.5 4 1.4
spp 7 0.9 1 0.3
Unknown 249 31.1 144 49.7
Total 800 100 290 100
India Ghana
Microscopy and culture negative 23 87
Microscopy positive, culture negative* 218 24
Microscopy negative, culture positive 8 33
Total 249 144
*Bacteria only.
Table 2 Identification of bacteria isolated from
corneal tissue of patients with suppurative keratitis
India Ghana
No % No %
Gram positive cocci
spp 110 46.8 8 20.0
Streptococcus pneumoniae
) (62) (26.4) (6) (15.0)
Staphylococcus aureus
5 2.1 2 5.0
Coagulase –ve staphylococci 58 24.7 2 5.0
spp 1 2.5
Gram positive bacilli
spp 2 0.9
spp 4 10.0
spp 3 1.3
Gram negative bacilli
spp 35 14.9 21 52.5
Pseudomonas aeruginosa
) (33) (14.0)
spp 11 4.7
spp 3 1.3
spp 1 0.4
spp 5 2.1
spp 2 0.9
Unidentified 2 5.0
Totals 235 100 40 100
Table 3 Identification of fungi isolated from corneal
tissue of patients with suppurative keratitis
India Ghana
No % No %
spp 141 39.9 46 42.2
spp 76 21.5 19 17.4
A flavus 59 (16.7) 9 (8.3)
A fumigatus 15 (4.2) 7 (6.4)
A niger 1 (0.3) 1 (0.9)
A nidulans 1 (0.9)
1 (0.3) 1 (0.9)
spp 34 9.6 1 0.9
Lasiodiplodia theobromae
1 0.3 6 5.5
spp 1 0.9
spp 2 0.6
Scedosporium apiospermum
2 0.6 2 1.8
Cephaliophora irregularis
Cladosporium cladosporoides
–– 10.9
spp 1 0.3
Exserohilum rostratum
spp 2 0.6
spp 1 0.9
Unidentified 35 9.9 5 4.6
Suspected, but culture negative 57 16.1 27 24.8
Totals 353 100 109 100
1212 Leck, Thomas, Hagan, et al on November 11, 2011 - Published by bjo.bmj.comDownloaded from
of corneal ulcers followed by staphylococci (26.8%) and
pseudomonads (14.9%). In both countries more than 80% of
bacterial isolates were represented by these three genera.
Fusarium spp and Aspergillus spp were isolated from 61% of
all fungal infections and comprised 83% of identified fungal
isolates (Table 3). Although Fusarium species were the most
prevalent fungal pathogens reported in Ghana, differences in
the spectra of fungi were observed between the participating
centres. In Accra (southern Ghana), 63% (27/43) of fungi iso-
lated were Fusarium spp compared with 31.3% (15/48) at
Bawku Hospital (northern Ghana), where a greater variety of
fungi were isolated. Lasiodiplodia theobromae was the third
commonest fungal isolate in Ghana. In India a greater
number, and diversity, of dematiaceous moulds were cultured;
Curvularia species were most frequently isolated.
Fungi were identified as the principal aetiolog ical agent of
cor neal ulceration: 44% and 37.6% of cases in India and
Ghana. Earlier studies in the same regions reported a similarly
high proportion of fungal keratitis.
A review of the
literature shows that there are distinct patterns of geographi-
cal variation in the aetiology of suppurative keratitis and con-
siderable variation in the proportion due to fungi has been
documented (Table 4). The proportion of corneal ulcers caused
by filamentous fungi increases towards tropical latitudes (Fig
1). In more temperate climates, fungal ulcers are uncommon
and are more frequently associated with Candida species than
filamentous fungi.
Houang et al
reviewed the relation of
fungal keratitis to climate concluding that, although a higher
incidence of fungal keratitis could be expected in countries
with similar annual rainfall and temperature range, this was
not always so and was also dependent on the extent of
Aspergillus spp and Fusarium spp are the most frequently
reported fungal pathogens isolated from cases of fungal kera-
titis in the tropics.
In both Ghana and south India the most
commonly isolated fungal pathogens in the current series
Table 4 Mycotic keratitis: a review of the literature
Place Reference Year Number cases % Fungi* Organism 1 Organism 2
London Coster
1981 67 3% 2 cases only
London, UK Personal comm 2001 72 3%
spp 58%
spp 26%
Sweden Neumann
1993 48 0%
North America
Florida Liesegang
1980 663 20%
spp 62%
spp 7.5%
Florida Rosa
1994 125
spp 62%
spp 12.5%
Philadelphia Tanure
2000 24
C albicans
spp 25%
California Ormerod
1987 227 11%
C albicans
spp 2%
Atlanta Harris
1988 108 32%
spp 94%
Northern USA O’Day
1987 33
spp 42%
spp 30%
Southern USA 285
spp 55%
spp 9.5%
South America
Paraguay Mino de Kaspar
1991 26 58%
spp 42%
spp 19%
The Middle East
Saudi Arabia Khairallah
1992 191 14%
spp 41%
Candida albicans
Ghana (Accra) Hagan
1995 199 34%
spp 52%
spp 15%
South Africa Carmichael
1985 274 2%
spp 33%
Nigeria Gugani
1976 59
spp 36%
spp 29%
Tanzania Mselle
1999 212 15%
spp 75%
spp 19%
South Africa Ormerod
1987 120 2.5% 3 different isolates
Nepal, Dharan Khanal
2001 86 44%
spp 60%
spp 13%
Nepal, Kathmandu Upadhyay
1991 405 17%
spp 47%
spp 13%
Nepal Chaudhary
1999 110 8%
spp 22%
Bangladesh Rahman
1998 63
spp 35%
spp 35%
Bangladesh Dunlop
1994 66 36%
spp 40%
spp 21%
Bangladesh Williams
1991 127 34%
spp 49%
spp 28%
Bangladesh Williams
1987 33 21%
spp 29%
spp 14%
India, North Chander
1994 730 8.4%
spp 40%
spp 16%
India, New Delhi Panda (children)
1997 211 10.8%
spp 40%
spp 11%
India, New Delhi Mahajan
1985 674 19.7%
spp 37%
spp 10%
India, Mumbai Deshpande
1999 367
spp 60%
spp 10%
India, Hyderabad Kunimoto
2000 102 19%
spp 37%
spp 16%
India, Hyderabad Garg
2000 557
spp 38%
spp 30%
India, Karnataka Kotigadde
1992 295 23%
spp 34%
spp 19%
India, Madras Sudaram
1989 150 45%
spp 53%
spp 12%
spp 12%
India, Madras Venugopal
1989 322
spp 64%
spp 8.4%
India, Tiruchiripalli Thomas
1986 774 32%
spp 38%
spp 30%
India, Madurai Rahman
1997 58
spp 38%
spp 17%
India, Madurai Srinavasan
1997 434 35%
spp 47%
spp 16%
Sri Lanka Gonawardena
1994 66 33%
spp 18%
single isolates
Thailand Imwidthaya
1995 145 25%‡
spp 34%
spp 26%
Singapore Wong
1997 29
spp 52%
A flavus
Hong Kong Houang
2001 223 2%
spp 60%
*Corresponds to the proportion of fungal keratitis cases in studies which were not exclusively reporting fungal keratitis.
†Percentages of fungal keratitis cases have been recalculated by the author to represent the proportion of fungal corneal ulcers as a percentage of the
total number of corneal ulcers reported, not just those which were culture positive. Numbers of cultures can be misleading particularly if multiple isolates
are cultured from the same patient.
‡No figures stated.
Aetiology of suppurative corneal ulcers in Ghana and south India 1213 on November 11, 2011 - Published by bjo.bmj.comDownloaded from
were Fusarium spp. Other studies in south India have reported
Fusarium spp to be more common than Aspergillus species.
Fusarium spp have also been found to be the principal fungal
pathogen in Florida, Paraguay, Nigeria, Tanzania, Hong Kong,
and Singapore (Table 4). Aspergillus species predominate in
northern India, Nepal, and Bangladesh.
This phenom-
enon may be explained by differences in climate and the
natural environment. A similar pattern was also observed in
Ghana. Although Fusarium spp were the most commonly iso-
lated fungi at all of the centres in Ghana, moulds with enter-
oblastic conidia adhering in dry chains—for example Aspergil-
lus spp and Paecilomyces spp, were more frequently isolated
from patients in the north of the country where the environ-
ment is drier and dustier, than in the more humid south. As
observed by Khairallah
the high proportion of corneal infec-
tions caused by Aspergillus spp in drier climes may be due to
the fact that spores of Aspergillus spp can tolerate hot, dry
weather conditions. Aspergillus spp also predominate in more
temperate latitudes.
A significant increase in the number of reported cases of
suppurative keratitis was observed during the harvest period
and windy seasons. However, the proportion of corneal ulcers
due to fungi remained consistently high throughout the year.
Other authors have made similar observations, noting an
increase in cases of fungal keratitis during the dry, windy sea-
sons compared with the wet, humid months of the year.
This trend is likely to be a direct consequence of increased
agricultural activity before and immediately following the
rains. Some studies have reported an increase during the hot
and humid months.
The majority of filamentous fungi associated with corneal
ulceration in the tropics are saprobic, thermophilic moulds
that are found widely in this environment. These are
ubiquitous in the soil and vegetation. Fusarium species are
common plant pathogens, particularly of cereal crops or
saprophytes of plant debris and are found in soil.
aspergilli are ubiquitous and have been found almost
everywhere on every conceivable type of substrate, including
soil and decaying organic debris. Some of the less common
isolates such as Bipolaris spp and Exserohilum spp are
pathogens of grasses. Curvularia spp mostly occur on dead
plant material.
Although injury by vegetable matter is
considered to be predictive for fungal keratitis, in this study
fungal corneal ulcers were more often preceded by dust or
mud particles in the eye.
A shift in the predominant bacterial pathogens was
observed when compared with earlier findings. In Ghana,
>50% of bacterial isolates were Pseudomonas species compared
with 27% of isolates in a previous study by Hagan et al.
is a paucity of information in the literature regarding the aeti-
ology of bacterial corneal ulcers in sub-Saharan tropical Africa
and, therefore, comparisons are only possible with similar
geographical and climatic reg ions outside the continent of
Africa. Pseudomonas species were identified as the commonest
bacterial isolate in a study of 142 cases of suppurative kerati-
tis in Bangladesh in a study by Dunlop et al and also by
Williams et al, who found that 40% of bacterial isolates were
Pseudomonas spp.
A predominance of Pseudomonas species
has been reported in Hong Kong, Flor ida, and Paraguay.
19 25 43
In reports from Nepal and south India, Gram positive cocci
have been reported as the primary cause of bacterial
In this study, Gram positive cocci accounted for
the majority (74%) of bacterial isolates in India, as found pre-
viously by Thomas et al.
The proportion of bacterial ulcers
caused by Streptococcus spp increased from 18.5% (1986) to
46.8% in this study. Similar diagnostic criteria were used in
the previous study and, therefore, the trend may be
attributable to a genuine change of bacterial flora within the
geographical area, as influenced by climate and environment.
Traditional diagnostic laboratory methods, including micro-
scopy and culture may be negative despite a clear clinical
presentation of suppurative keratitis. This was true in 50% and
31% of cases in Ghana and India, respectively. This may be due
to difficulty in obtaining sufficient corneal material for
conventional investigation. This applies particularly to large,
late stage ulcers, because of the risk of perforation and,
conversely, early stage, small ulcers from which little material
is available. It is imperative that the quality and quantity of
specimen is optimal for accurate laboratory diagnosis. Self
administration of antibiotics by patients before seeking medi-
cal attention has been thought to affect the recovery of organ-
isms in culture.
It is possible culture positivity correlated with
inappropriate antibiotic usage.
Although there were a high proportion of corneal ulcers in
Ghana for which the aetiology was not determined, the
number of proved fungal ulcers at each of the centres was
greater than the number of proved bacterial ulcers. It is there-
fore not unreasonable to assume that this trend could be
It is usually not possible to determine the significance of
bacteria observed by microscopy alone. Small numbers of
Gram positive cocci may be contaminants from the lid margin.
Conversely, the presence of fungal hyphae in corneal tissue is
significant. In agreement with Dunlop et al the sensitivity, spe-
cificity, and predictive value of Gram stain microscopy is much
higher for fungal ulcers than those caused by bacteria.
In this
study 95% of fungal infections could have been diagnosed
based on the findings from microscopy alone. This is an
important conclusion, since the majority of rural based clinics
in areas where suppurative keratitis is a problem do not have
culture facilities but m ay be able to perform simple
microscopy. A wet mount preparation, using lactophenol cot-
ton blue stain, was used as a supplementary stain in this
Figure 1 Suppurative keratitis due
to fungi as a proportion of total
number of cases, by latitude.
1214 Leck, Thomas, Hagan, et al on November 11, 2011 - Published by bjo.bmj.comDownloaded from
study. Where scientific expertise, and/or resources, may be an
issue, it is easier to observe fungal hyphae employing this
method than using the potassium hydroxide (KOH) tech-
nique. Reports into the presence of fungi in the eyes of
asymptomatic individuals, have shown that a wide variety of
fungi may be transient in the conjunctival sac. This may be the
case in as many as 37% of healthy eyes, thereby discounting
the use of single culture.
In conclusion, it is imperative to know the “local” aetiology
of keratitis in a particular region. Our comparative study dem-
onstrates that there were differences between two countries
with similar tropical climates at the same latitude. Equally,
differences were observed within the same country. This is
important information with regard to management, as many
eye units do not have microscopy or culture facilities. Diagno-
sis is then dependent on clinical acumen and the treatment
provided is, at best, empirical. It is clear that it is important to
know the local aetiology, particularly if diagnosis is going to be
reliant on clinical signs alone. Changing patterns of disease
have also occurred in temperate, developed countries, as
exemplified by the increase in keratitis due to Pseudomonas spp
and Acanthamoeba spp in recent years. Awareness of changes in
aetiology and antimicrobial resistance, when this information
is available, are critical to managing keratitis cases.
The authors would like to thank the staff of Korle Bu, Bawku, and
Agogo hospitals (Ghana) and Musir i, Ariyalur, and Myladthurai hos-
pitals (India) for their assistance during this study. Also, Miss Linda
Ficker, Dr Allen Foster, and Dr Elizabeth Wright for their clinical
Authors’ affiliations
A K Leck, G J Johnson, Department of Infectious and Tropical Diseases,
Clinical Research Unit, London School of Hygiene and Tropical Medicine,
Keppel Street, London WC1E 7HT, UK
P A Thomas, J Kaliamurthy, M John, C M Kalvathy, C A N
Jesudasan, Institute of Ophthalmology, TELC-Joseph Eye Hospital,
Tiruchirapalli, South India
M Hagan, E Ackuaku, M J Newman, F S Codjoe, J A Opintan, V
Essuman, Korle Bu Teaching Hospital, Accra, Ghana
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Aetiology of suppurative corneal ulcers in Ghana and south India 1215 on November 11, 2011 - Published by bjo.bmj.comDownloaded from
doi: 10.1136/bjo.86.11.1211
2002 86: 1211-1215Br J Ophthalmol
A K Leck, P A Thomas, M Hagan, et al.
fungal keratitis
Ghana and south India, and epidemiology of
Aetiology of suppurative corneal ulcers in
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... Specific treatment requires quick and accurate identification of the causative microorganisms. 6 The epidemiological pattern and causative agents for suppurative corneal ulcer varies significantly from country to country, and even from region to region within the same country. It is important to determine the "regional" aetiology within a given region for comprehensive strategy for the diagnosis and treatment of corneal ulcer. ...
... It is important to determine the "regional" aetiology within a given region for comprehensive strategy for the diagnosis and treatment of corneal ulcer. 6 Several studies have addressed these questions in the Indian subcontinent. 1,2,5,[7][8][9][10][11][12][13][14][15][16][17][18][19][20] But only one small-size study is available from rural Bengal 19 and one study on fungal keratitis from Assam (Medline Search). ...
... When KOH smears were positive for amoebic cysts, a further corneal scraping was performed and the material was inoculated onto non-nutrient agar overlaid with Escherichia coli; this was discarded if there was no growth after 7 days. 6 Bacterial cultures were considered positive only if growth of the same organism was demonstrated on both media or there was semi confluent growth at the site of inoculation on one media with identification of morphological characteristics of similar organism in Gram Stain. 6 The specific identification of bacterial pathogens was based on microscopic morphology, staining characteristics and biochemical properties using standard laboratory criteria. ...
Purpose: The purpose was to study the demographical factors and microbial etiology associated with infective keratitis in a tertiary care center in West Bengal. Materials and Methods: In this cross-sectional study, 142 patients with suspected microbial keratitis were enrolled from June 2019 to May 2020. After taking the history and diagnosing the infective ulcer clinically, the corneal scrapings and cultures were evaluated. The smears were fixed with Gram stain and 10% potassium hydroxide wet preparation. The scrapped material was inoculated in blood agar and Sabouraud dextrose agar for culture. Results: Ocular trauma was the most common predisposing factor in 94 (70.6%) corneal ulcers (P < 0.0001). The most common etiologic agent causing corneal injury was wooden object (38.3%). Microbial etiology was established in 76 (53.52%) corneal scrapings. Out of the total culture-positive cases, 45 patients (31.7%) had pure fungal infections, 25 patients (17.6%) had pure bacterial infections, and 6 patients (4.2%) reported mixed infections. Among the fungal pathogens, Aspergillus species was the most common fungal isolate (29 cases, 56.8%), followed by Fusarium species (17 cases, 33.3%) and Candida species (5 cases, 9.8%). The most common bacterial isolate was Staphylococcus aureus (16 cases, 51.6%), followed by Pneumococcus species (7 cases, 22.5%). Conclusion: Trauma with wooden material was the most common predisposing factor for infective keratitis. Fungal ulcers predominated in the study findings. Aspergillus species and S. aureus were the most common fungal and bacterial isolates, respectively. Regional variations exist in the microbial etiology of infective keratitis.
... If ocular infections are untreated, severe morbidities may arise. Isolation of the offending microorganisms is essential, as patterns vary with geographic location (9)(10)(11)(12)(13)(14)(15)(16). In addition to geographical variations, temporal trends are likely to influence the etiology of ocular infections (4). ...
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Background: We aimed to elucidate the pathogenic bacterial and fungal profiles of specimens obtained from suspected ocular infections at Farabi Eye Tertiary Referral Hospital, Tehran, Iran. Methods: In this cross-sectional study, we collected data from ocular specimens taken during the seven-year period of 2011 to 2018, and the results were then retrospectively analyzed. Samples had been obtained from patients who were investigated for ocular infections. Results: Overall, 16,656 ocular samples were evaluated. The mean patient age was 48.31 ± 26.62 years. Most patients were men (60.33%), and men in the 7th decade of life were the largest represented group. The seasonal distributions of specimen collection sites followed the overall distribution of collection sites by year. Specimens obtained from the cornea were the most common (49.24%), also representing the largest number of specimens in all seasons. The most commonly isolated fungal microorganisms were Fusarium spp., followed by Aspergillus spp. and Candida albicans. Of the 6,556 specimens with positive bacterial cultures, 59% produced gram-positive bacteria, while the remainder produced gram-negative pathogens. The most commonly isolated bacteria were Pseudomonas aeruginosa (17.77%), Staphylococcus epidermidis (13.80%), Streptococcus pneumoniae (13.27%), S. viridans (12.23%), and S. aureus (11.18%). Conclusion: Most submitted specimens were obtained from the cornea. The most commonly isolated fungal microorganisms were Fusarium spp., followed by Aspergillus spp. and C. albicans. The most commonly isolated bacteria were P. aeruginosa, followed by S. epidermidis and S. pneumoniae. Keywords: Microbiological profile; Ocular infection; Bacterial; Fungal; Eye; Ocular specimen
... 3 Multiple investigations, performed in different areas of the world, have reported a high incidence rate of ocular co-infection by bacteria and fungi. [3][4][5][6][7] According to a 10-year study at a tertiary referral center in the USA, a relatively high incidence rate of mixed bacterial-fungal infections was reported. 8 Therefore, the possibility of a co-infection by bacterial and fungal microorganisms should be considered. ...
Full-text available
Introduction: Untreated ocular infections can damage the unique fine structures of the eye with possible visual impairments and blindness. Ciprofloxacin (CIP) ophthalmic solution is prescribed as first-line therapy in ocular bacterial infections. Natamycin (NT) ophthalmic suspension is one of the progenitors in ocular antifungal therapy. Nanostructured lipid carriers (NLCs) have been widely examined for ocular penetration enhancement and distribution to deeper ocular tissues. The objective of the current study was to prepare NLCs loaded with a combination of CIP and NT (CIP-NT-NLCs) and embed them in an in-situ gelling system (CIP-NT-NLCs-IG). This novel formulation will target the co-delivery of CIP and NT for the treatment of mixed ocular infections or as empirical treatment in case of limited access to healthcare diagnostic services. Methods: CIP-NT-NLC and CIP-NT-NLC-IG formulations were evaluated based on physicochemical characteristics, in vitro release, and ex vivo transcorneal permeation studies and compared against commercial CIP and NT ophthalmic eye drops. Results and discussion: NLCs formulation (0.1% CIP and 0.3% NT) showed particle size, polydispersity index, and zeta potential of 196.2 ± 1.2 nm, 0.43 ± 0.06, and -28.1 ± 1.4 mV, respectively. Moreover, CIP-NT-NLCs showed entrapment efficiency of 80.9 ± 2.9 and 98.7 ± 1.9% for CIP and NT, respectively. CIP-NT-NLCs-IGformulation with 0.2% w/v gellan gum demonstrated the most favorable viscoelastic characteristics for ocular application. CIP-NT-NLCs and CIP-NT-NLCs-IG formulations exhibited a sustained release pattern for both drugs over 24 h. Moreover, CIP-NT-NLCs and CIP-NT-NLC-IG formulations showed 4.0- and 2.2-folds, and 5.0- and 2.5-folds enhancement in ex vivo transcorneal permeability of CIP and NT, respectively, compared to the control formulations. Conclusion: The results suggest that this dual nanoparticulate-based in-situ gelling drug delivery system can serve as a promising topical delivery platform for the treatment of ocular infections.
... However, the simultaneous increase in abundance of Aspergillus and Candida in BK-SW and Absidia in BK-CR, which are human pathogens, may support the inflammatory status of keratitis. In fact, Aspergillus keratitis is an important ophthalmological problem across the world (84)(85)(86). Candida is also a common causative agent of keratitis, and different species of Candida such as Candida albicans, C. krusei, C. fermentati, C. famata, C. glabrata, C. tropicalis, C. parapsilosis, and C. guilliermondii have been reported to be associated with the eye of individuals with keratitis (61,(87)(88)(89). Species of Absidia, like Absidia corymbifera, caused keratitis in an immunocompetent male patient with no corneal injuries (90) and also in individuals following trauma (91,92). ...
Full-text available
Inflammation of the cornea is known as keratitis, and bacteria, fungi, protozoans, and viruses are the etiological agents of this disease. Delayed treatment of keratitis could result in loss of vision and, under certain severity conditions, the removal of an eye and its associated structures. In the current study, the ocular surface (conjunctiva and cornea) mycobiomes of individuals with bacterial keratitis were compared with the ocular mycobiome (conjunctiva) of healthy individuals, free of any ocular morbidity. Mycobiomes were generated through NGS approach using conjunctival swabs and corneal scrapings as the source of DNA from which ITS2 was amplified and sequenced, as a proxy to identify fungi. The results indicated significant changes in the alpha-diversity indices and in the abundance at the phylum and genera level. Hierarchical clustering using a heatmap showed that the mycobiomes were different. Furthermore, NMDS plots also differentiated the mycobiomes in the three cohorts, implying dysbiosis in the mycobiomes of the conjunctivae and corneal scrapings of bacterial keratitis individuals compared to control individuals. A preponderance of negative interactions in the hub genera in the conjunctival swabs of bacterial keratitis individuals compared to healthy controls further re-emphasized the differences in the mycobiomes. The dysbiotic changes at the genera level in conjunctivae and corneal scrapings of bacterial keratitis individuals are discussed with respect to their possible role in causing or exacerbating ocular surface inflammation. These results demonstrate dysbiosis in the ocular mycobiome in bacterial keratitis patients compared to healthy controls for the first time.
... Leck, et al. reported that men are more susceptible to conjuctivitis than female [16]. In another studies Sharma et al and Shokohi, et al. reported that Mycotic Keratitis seems to be prevalent in males, in farmers and the most common predisposing factor remains trauma to the cornea [17][18]. ...
... Leck, et al. reported that men are more susceptible to conjuctivitis than female [16]. In another studies Sharma et al and Shokohi, et al. reported that Mycotic Keratitis seems to be prevalent in males, in farmers and the most common predisposing factor remains trauma to the cornea [17][18]. ...
... [9] The median culture positivity rate from clinically diagnosed cases of MK is 50.3% and stains achieve diagnosis in only 27.3%-61.6% of cases. [10][11][12] The relative insensitivity of these methods is attributable to prior antibiotic use, technical difficulties in growing organisms from small samples, and difficulties in immediate incubation of culture plates to optimize diagnostic yield. [13] The relatively small quantity of infected material that can be sourced from the cornea add to the difficulty. ...
Aim: To explore the factors associated with culture positivity and worsening of corneal ulcers in patients presenting to a tertiary care teaching hospital in south Kerala. Methods: We did a retrospective review of hospital-based case records from June 2018 to May 2019 and included all cases of infective corneal ulcer admitted during the period of study with corneal stromal infiltrate on slit-lamp examination. Results of gram stain, potassium hydroxide stain, and culture result were noted. The treatment history (moxifloxacin (0. 3%) or fortified cephalosporin and gentamicin or natamycin) was recorded. The data were exported to the statistical software SPSS V27.0 for further analysis. Results: The data of 125 culture-positive and 250 culture-negative ulcers were studied. Most patients were aged >55 years (n = 201, 53.6%) and 35–55 years (n = 120, 32.0%). The association of culture negativity with nontraumatic risk factors was significant (P = 0.01) but not with the size of the ulcer, progress score, or worsening clinical status of the ulcer. More persons with pretreatment (15.2%) showed worsening of the clinical status compared to those who did not (6.3%) (P = 0.005). 63% of the culture-positive cases had not taken any pretreatment. Compared to noncentral ulcers there was a marked deterioration of central ulcers (16.7%) (P = 0.005). Conclusion: Pretreatment and centrally located ulcers were significantly associated with a worsening clinical condition in this study. Culture-positive corneal ulcers showed a tendency toward improvement, but we could not find an association between the detection of the organism and its favorable response to treatment.
Full-text available
To report demographic, microbiological, therapeutic, anatomical, and visual results of corneal ulceration in the elderly patients seen at a tertiary eye care centre in south India. 102 consecutive cases of microbial keratitis in patients 65 years and older were studied. Inclusion criteria were: (i) presence of corneal stromal infiltrate upon slit lamp examination; and (ii) microbiological evaluation of corneal scrapings for suspected microbial keratitis. The principal predisposing factors identified in this study were ocular disease (38.2%), previous ocular surgery in the same eye (29.4%), trauma (17.6%), and severe systemic disease (16.7%). Contact lens wear was associated with only two cases (2.0%). 99 organisms were isolated in cultures of corneal scrapings from 74 (72.5%) of the 102 cases. Staphylococcus epidermidis (31.1%), filamentous fungi (25.7%), and Streptococcus pneumoniae (13.5%) were the most common isolates. 12 eyes (11.8%) required surgery, 15 (14.7%) eventually required evisceration, and nine (9.6%) of the 94 followed patients achieved an unaided vision of 20/60 or better at last follow up. This work represents the largest recent single centre study on (non-viral) microbial keratitis in the elderly, its management, and outcomes of therapy. While the predisposing factors differ from those of general population, the spectrum of microbes responsible for keratitis in the elderly appears to reflect the local microbial flora rather than a predilection for elderly patients. Delay in diagnosis and systemic conditions associated with advancing age probably contribute to poorer outcome from therapeutic measures.
Full-text available
To determine the epidemiological characteristics and risk factors predisposing to corneal ulceration in Madurai, south India, and to identify the specific pathogenic organisms responsible for infection. All patients with suspected infectious central corneal ulceration presenting to the ocular microbiology and cornea service at Aravind Eye Hospital, Madurai, from 1 January to 31 March 1994 were evaluated. Sociodemographic data and information pertaining to risk factors were recorded, all patients were examined, and corneal cultures and scrapings were performed. In the 3 month period 434 patients with central corneal ulceration were evaluated. A history of previous corneal injury was present in 284 patients (65.4%). Cornea cultures were positive in 297 patients (68.4%). Of those individuals with positive cultures 140 (47.1%) had pure bacterial infections, 139 (46.8%) had pure fungal infections, 15 (5.1%) had mixed bacteria and fungi, and three (1.0%) grew pure cultures of Acanthamoeba. The most common bacterial pathogen isolated was Streptococcus pneumoniae, representing 44.3% of all positive bacterial cultures, followed by Pseudomonas spp (14.4%). The most common fungal pathogen isolated was Fusarium spp, representing 47.1% of all positive fungal cultures, followed by Aspergillus spp (16.1%). Central corneal ulceration is a common problem in south India and most often occurs after a superficial corneal injury with organic material. Bacterial and fungal infections occur in equal numbers with Streptococcus pneumoniae accounting for the majority of bacterial ulcers and Fusarium spp responsible for most of the fungal infections. These findings have important public health implications for the treatment and prevention of corneal ulceration in the developing world.
Full-text available
A clinical and mycological study of 21 cases of mycotic keratitis, a clinical entity not yet reported from Nigeria or West Africa, showed that Fusarium solani was the predominant aetiological agent. It was isolated from 12 cases. Four of the remaining nine cases were caused by Aspergillus fumigatus, one by A. flavus, two by Penicillium citrinum, and one each by P. expansum and Penicillium sp. All the 12 isolates of F. solani grew well at 37 degrees C and survived at 40 degrees C. Two cases, one due to F. solani and the other to A. fumigatus, were accompanied by panophthalmitis.
During the years 1981 to 1982, 674 clinical specimens from cases of ulcerative keratitis were processed in the ocular microbiology laboratory. Bacterial cultures were positive in 44.2%, fungal in 11.6% of the cases, and another 8.2% cultured both bacteria and fungi. The remaining 36% were sterile. Staphylococcus was the most common isolate; Pseudomonas and Acinetobacter were the next most common pathogens. Moraxella and Haemophilus were conspicuously absent, which strongly suggests that the routine inclusion of more media such as chocolate agar is desirable. Aspergillus was the most common fungus recorded among the fungal isolates. Mycotic ulcers were diagnosed both clinically and by laboratory workup. Discrepancies between clinical diagnosis and laboratory findings have been recorded. In our experience, cloxacillin has been adjusted to be the most effective drug in the treatment of staphylococcal infections, and polymyxin B for infections due to Pseudomonas. Chloramphenicol has been found to be as effective as gentamicin.
Purpose: To evaluate the demographic features, clinical profile, and laboratory diagnosis in cases of mycotic keratitis in children. Methods: We retrospectively analyzed 211 cases of mycotic keratitis in children younger than 16 years over a 5-year period in a tertiary eye center. Culture-proven cases of fungal keratitis were reviewed. Results: Trauma was the most common predisposing factor (55.3%), followed by associated systemic illness (11.2%), previous ocular surgery (9.8%), and others. Corneal injury contaminated with vegetable matter was responsible for 60.5% of traumatic cases. Aspergillus species were the most frequent isolates (39.5%). Others included Fusarium (10.7%), Alter-naria (10.2%), Curvularia (7.4%), and Penicillium (7%). A seasonal variation in the incidence of mycotic keratitis revealed a peak incidence in the months of September and October. One hundred sixty-two children (76.7%) cooperated for examination and scraping under topical anesthesia with or without sedation. General anesthesia for scraping was required in 49 (23%) of 211 children for corneal scraping. Gram stains of corneal scraping were positive for hyphal elements in 54.5% of cases, and potassium hydroxide wet-mount preparation was positive in 90.2% of cases. Conclusions: This study highlights important risk factors and organisms responsible for mycotic keratitis in children.
Suppurative keratitis is an important preventable cause of blindness, particularly in the developing world. This study analyses 142 cases of suppurative keratitis referred to Chittagong Eye Infirmary, Bangladesh. Some 53.5% of cases were bacterial and 35.9% were fungal. The five most common pathogens were: Pseudomonas sp. 24%, Streptococcus pneumoniae 17%, Aspergillus sp. 13%, Fusarium sp. 7% and Curvularia sp. 6%. Gram stain and culture results were consistent in 62.6% of cases. Previous antibiotic treatment was a significant factor for failure of culture isolation and less so for Gram stain failure. On Gram stain, 55.9% of pseudomonal cases were missed, but only 2% of fungal cases were missed. Over all, Gram stain had a sensitivity of 62% and positive predictive value of 84% for bacterial cases, and 98% and 94% for fungal cases, respectively. Fungal ulcers were typically filamentous, but an antecedent history of trauma was not common. The most frequent injury was due to rice grains, but the inoculum appeared to be introduced during eye washing with contaminated water. Pseudomonal ulcers occurred most frequently in the monsoon season, and Fusarium cases were seen only in the hot, dry season.
The encounter of the microorganism with the cornea is a complex event which generates tissue destruction through multiple host and organism-derived mediators. Suspicion of microbial invasion, proper utilization of the microbiology laboratory, and initiation of effective antimicrobial agents are the crucial measures in controlling the replicating organism and preserving visual function.
The initial treatment of bacterial ulcers of the cornea should consist of a combination of antibiotics that are effective against the major pathogens in the community. A gram stain may be misleading and therefore may suggest inappropriate therapy. Antibiotic therapy should include subconjunctival injections and concentrated eye drops, but not systemic administration except following perforation. Initially, we use cefazolin and tobramycin or gentamicin. Bacitracin may be substituted as a topical medication. Antibiotic therapy should be changed only if the pathogen is reported to be resistant to initial therapy and if the corneal ulcer continues to worsen.