Ocular infections cause damage to structures of the eye, which leads to
reduced vision power and even blindness, if left untreated. Mostly the
bacterial pathogens are involved in infections of the eye disorders.
Conjunctiva, lid and cornea are the most frequently affected parts of the eye.
A healthy conjunctiva is essential, to maintain the healthy cornea and to
increase the visual acuity of the eye (Jorgensen et al., 2015; Ubani,
Bharathi et al., 2003 reported that bacterial infections of the
eye spread to adjacent tissue due to predisposing factors such as trauma,
ocular surface disease, contact lens wear, ocular adrenal dysfunction, previous
surgery and other exogenous factors. In another study, (Leibowitz, 2005; Seal and
Uwe, 2007) reviewed that the defense mechanisms of the outer eye may be altered
by inmunosuppression and systemic diseases which permits bacteria to spread.
Ocular infections due to widespread use of topical and systemic inmunosuppressive
agents are the only reasons to increase the opportunistic pathogens. The
spectrum of organisms, causing conjunctivitis, varies around the world.
Worldwide, the increased incidence of morbidity and blindness is caused by the
microorganisms, which are known to cause external ocular infections such as conjunctivitis,
blepharitis, hordeolum, keratitis and dacryocystitis, etc., (Modarrres et
Sharma, 2011,suggested that
bacteria are known to cause ocular surface infections such as conjunctivitis.
Both aerobic and anaerobic bacteria like gram-negative Bacilli,
Pseudomonas species, Escherichia species, Citrobacter
species, Klebsiella species, Serratia species, Proteus species,
Actinobacillus species, Flavobacterium species, Haemophilus species, Bacteroides species
and Fusobacterium species, Gram-negative cocci and
coccobacilli (aerobes)- Neisseria species, Moraxella species and Acinetobacter species, gram-positive aerobic
and/or facultative anerobic cocci- Micrococcus species, Staphylococcus species and Streptococcus species. Gram-positive anerobic cocci – Peptostreptococcus species,
gram-positive bacilli – Bacillus species, Clostridium
species, Actinomycetes and related organisms like Corynebacterium
species, Porpionibacterium species, Actinomyces species, Mycobacterium
species and Nocardia species are the most common causative agents for external ocular infections. Streptococcus pneumonia,
Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, Staphylococcus epidermidis,
Escherichia coli, Chlamydia trachomatis, Bacillus cereus, Neisseria gonorrhoea,
Staphylococcus aureus and Staphylococcus
epidermidis could also cause ocular infections. (Everett et al., 1995; Starr et al., 2000;
Cuong and Michael, 2002).
Weingeist et al., 2001 reported that conjunctivitis is the most
important disease of the conjunctiva. The term, conjunctivitis, describes the
inflammation process that involves in conjunctivae and it is the most conmon,
non traumatic eye complaint. Both eyes are usually affected at the same time
although it starts from one eye and spreads to the other eye, after a day or
two (McEwan, 2002).
Some reports have documented different stages of conjunctivitis. Healthy
conjunctiva is invaded by bacteria, to produce a primary bacterial
conjunctivitis. The organisms are completely virulent, and the inflammation is
acute, severe and bilateral. The conjunctivitis is caused by many different
bacteria such as Staphylococcus species.
An acute primary conjunctivitis may also cause secondary conjunctivitis, if
left untreated. Haemophilus influezae
cause seasonal epidemics of conjunctivitis, in hot and dusty climates. The
severe conjunctivitis is caused by Gonococcus species. Pneumococcus,
Meningococcus and Streptococcus species, Moraxella lacunata causes
mild conjunctivitis (Sandford-Smith., 1990).
2.2 Isolation and identification of
bacteria from conjunctiva
Ramesh et al., 2010 studied and reported the specific bacterial pathogens, which is
responsible for causing ocular infections and determined their invitro
antibacterial susceptibilities to commonly used antibacterial agents. Eyelids
and conjunctiva are frequently affected by Staphylococcus aureus and it is treatment with flouroquinolones, ofloxacin and
gatifloxacin, which represented a good choice against bacterial ocular
A total of 89 conjunctival specimens were collected from the patients of
Taif University, Saudi Arabia. The potential bacterial isolates, from external
ocular infections and their antimicrobial susceptibility patterns were studied.
Isolates were identified as Staphylococcus aureus, Streptococcus pneumonia, Staphylococcus epidermidis, Klebsiella pneumoniae, Streptococcus pyogenes, Bacillus subtilis, Escherichia
roseus, Enterobacter aerogenes and Pseudomonas aeruginosa. In vitro ceftriaxone was
effective against 74.9% of isolated pathogens. Erythromycin and ceftriaxone
were more susceptible against Gram positive isolates and gentamycin and chloramaphenicol
were more susceptible to Gram negative isolates. From these data, erythromycin
and gentamycin are have been reported effective against most isolated pathogens
(Shahaby et al., 2015).
A total of 25 conjuctival samples were collected, from the cataract
patients, in the age group above 50 years, from Government Hospital,
Kanchipuram. Based on morphology, cultural and biochemical characteristics, out
of 25 samples collected, 18 were found to be (CONS) Coagulase Negative Staphylococcus
species, six were found to be Staphylococcus aureus and one as Escherichia
coli (Sumathi and Preethi, 2016).
Sherwal and Verma, 2008 studied 250 patients, who were
infected with conjunctivitis, in the Department of Microbiology, Lady Hardinge
Medical College and New Delhi. In this study, they reported that the bacteria
identified were Staphylococcus aureus
(19.13%), Streptococcus pneumoniae (10.93%), Streptococcus pyogens (0.55%), Pseudomonas aeruginosa (4.92%), Klebsiella species (2.74%), Escherichia coli (1.10%) and Proteus mirabilis (0.55%).
Funke et al., 1998 reported that
fifteen strains of Corynebacterium macginleyi were exclusively isolated,
from conjunctival swabs of patients, who were infected with conjunctivitis and
it was found to be is susceptible to quinolones, penicillins and
A total of 65 patients, the from Ophthalmology Department of Out Patient
Services of Dhulikhel Hospital, Nepal, were taken for the study. The data
indicated that gram positive cocci were found in 6.2% of cases and among them, Streptococcus pneumonia were observed in
seven cases (10.8%). In according to the invitro susceptibility testing,
gentamicin and chloramphenicol were the most sensitive (78.6% of samples) drugs
for conjunctivitis (Sthapit et al.,
another study Everitt et al.,
2006 detected bacterial growth in 50% of conjunctival swab, and the
organisms were Streptococcus pneumoniae (16 swabs, 23%), Haemophila influenzae
(26 swabs, 38%), and Staphylococcus aureus (11,
16%). Similar bacterial isolates were identified (Steven J. Lichtenstein et al., 2006; Greenberg, et al.,
Aamal Ghazi Mahdi, 2009, collected 175 conjunctival samples of newborn children, infected by
Ophthalmia neonatorum from an educational hospital for children in Al Diwaniya
city. Totally, 149 bacterial isolates were collected and in this sample, gram
positive bacteria were dominating, which included Staphylococcus aureus (54.36%)
and Streptococcus pyogenes (35.57%),while the gram negative
bacteria were Pseudomonas aeuroginosa (6.71%), Proteus species (1.34%),Neisseria
gonorrhoeae (1.34%) and Moraxella lacunata (0.67%).