Bacterial pathogens in conjunctivitis and corneal ulcers with special reference to Streptococcus pneumoniae, in early 2008, in the National Eye Hospital, Sri Lanka

Abstract

Introduction: The most important and frequently occurring eye infections are conjunctivitis and corneal ulcers. Though the significance of Streptococcus pneumoniae in eye infections is well-known, identification of causative serotypes is important for comparison with serotypes causing invasive diseases. Objectives: To describe the spectrum and characteristics of bacterial pathogens associated with conjunctivitis and corneal ulcers with special reference to S. pneumoniae.Methods: A descriptive cross-sectional study was carried out from January to April 2008 in which samples were collected from patients above one month old with suspected conjunctivitis or corneal ulcers seen in the out-patients department and wards of the National Eye Hospital, Colombo, Sri Lanka. Both eye swabs (n=322) and corneal buttons (n=31) were cultured. Isolated bacteriawere identified as far as possible and antibiotic sensitivity testing done. S. pneumoniae isolates were stored in sheep blood agar slants at -70 ºC and serotyped. Results: There were 296 conjunctival swabs and 26 corneal swabs. From 296 conjunctival swabs 118 (39.8%) samples yielded no bacterial growth. There were 185 bacterial isolates from 159 significant positive samples. The most frequently isolated bacteria were coagulase negative Staphylococcus sp. (n=58: 31.4%), and second commonest was S. pneumoniae (n=33: 17.84%). From 57 samples from patients with corneal ulcers, 47 (82%) did not yield any bacterial growth. Sensitivity to chloramphenicol was high among Staphylococcus sp., S. pneumoniae, Haemophilus influenzae, Moraxella sp and coliforms. Among pneumococcal isolates serotyped, 19F was predominant. Conclusion: Coagulase negative staphylococci were predominantly isolated from eye swabs and corneal buttons, but the most significant frequent isolate was S. pneumoniae. Except Pseudomonas, >90% isolates were sensitive to chloramphenicol. The predominant pneumococcal serotype was 19F.

Keywords

• bacterial pathogens, conjunctivitis, corneal ulcers, streptococcus pneumoniae