Bacterial pathogens associated with conjunctivitis and corneal ulcers with special reference to Streptococcus pneumoniae.

Abstract presented for the annual scientific sessions of the college of
microbiologists - 2009

Piyasiri D.L.B. 1, Chandrasiri P.2, Wijesinghe P.R.3
Post Graduate Institute, Colombo 1, National Hospital, Colombo 2, Epidemiology Unit, Colombo 3

Introduction.
The most important and frequently occurring corneal infections are conjunctivitis and corneal ulcers.This study was undertaken to isolate the common bacterial pathogens with special reference to Streptococcus pneumoniae and to test their antibiotic sensitivity pattern. Pneumococcal serogrouping was done to compare with the strains causing invasive infections.

Method.

Total 357 samples from patients with conjunctivitis or corneal ulcers were processed. Culture and identification was done by standard microbiological techniques. Antibiotic sensitivity was performed using Joan-Stokes and CLSI methods. All Pneumococcal isolates were tested for Minimum inhibitory concentration (MIC) of penicillin, and 37 were serogrouped.

Results. ( Pl refer to the picture)


Of 196 isolates, coagulase negative Staphylococcus spp (31.6%), was the most frequent. Of 203 direct Gram stains, 22.7% were smear positive and out of that, 89% were culture positive. For Strep.pneumoniae, routine ABST gave 70.7% Penicillin resistance while according to MIC, 6.5% were resistant and 60.9% were intermediately sensitive. Sensitivity for Chloramphenicol of Strep.pneumoniae, Strep.viridans, and Haemophilus was 97.7%, 100% and 93.1% respectively. Of 37 pneumococcal isolates which were serotyped, 12 isolates were 19F (32%), 6 isolates were 23A, and 4 isolates were serotype 3. Three were non-typeable.


Conclusion.

Coagulase negative Staphylococcus spp was the commonest isolate. Positive direct smears are valuable in treating patients empirically. Except Pseudomonas spp, >90% isolates were sensitive to Chloramphenicol. Of pneumococcal serotypes causing external eye infections, 56.8% were vaccine constituents and vaccine related ones.

o Part of this research has been presented in the annual academic session of college of ophthalmologists, Sri Lanka, in October, 2008.

o Financial assistance given by the Epidemiology Unit, Colombo, through SAPNA project is acknowledged.