Serotype distribution of Streptococcus pneumoniae isolates from ophthalmic & systemic infections & of commensal origin. Upendra K. Kar, Gita Satpathy, ...
Indian J Med Res 124, July 2006, pp 99-104
Serotype distribution of Streptococcus pneumoniae isolates from ophthalmic & systemic infections & of commensal origin Upendra K. Kar, Gita Satpathy, N. Nayak, B.K. Das* & S.K. Panda**
Department of Ocular Microbiology, Dr R. P. Center for Ophthalmic Sciences, Departments of *Microbiology & **Pathology, All India Institute of Medical Sciences, New Delhi, India
Received April 26, 2005
Background & objectives: Information regarding serotype distributions of Streptococcus pneumoniae causing ophthalmic infections is scanty. This study was therefore undertaken to determine the antimicrobial susceptibility status and serotypes of S. pneumoniae isolated from various ophthalmic infections and to compare with those isolated from systemic infections and commensal nasopharyngeal flora. Methods: Thirty eight of S. pneumoniae isolates from ophthalmic infections, 9 from systemic infections and 14 from the nasopharynx of apparently healthy school children were biochemically characterized and tested for in vitro antimicrobial susceptibity to various antibiotics. Serotyping of these 61 isolates was done by a rapid co-agglutination method. Results: All the 61 isolates were sensitive to oxacillin (penicillin) and susceptibility against other antimicrobials was variable. No multidrug resistance was observed. The 38 ophthalmic isolates were distributed in 15 different serotypes. Most prevalent serotypes were 14, followed by 8 and 19F. The 9 systemic and 14 commensal. isolates of S. pneumoniae were distributed in 7 and 11 serotypes respectively. Three of the systemic and six of the commensal serotypes were observed in ophthalmic infections whereas four of the commensal serotypes were observed in systemic infections. Interpretation & conclusion: Resistance to penicillin was not observed. In ophthalmic infections, a wide range of serotypes of S. pneumoniae were observed. More than half of the commensal serotypes obtained in the study as well as majority of the systemic serotypes were observed in ophthalmic infections.
Key words Commensals - in vitro antimicrobial susceptibility - ophthalmic infections - serotyping - Streptococcus pneumoniae systemic infections 99
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INDIAN J MED RES, JULY 2006
Streptococcus pneumoniae is an important pathogen in ophthalmic infections like infective keratitis, dachryocystitis and conjunctivitis 1-4. In India, S. pneumoniae is the most common bacterial cause of dachryocystitis, which if left untreated, leads to nasolachrymal duct blockage with grave sequelae 1,3 . S. pneumoniae has been shown to constitute 11.74 per cent of all bacterial isolates causing ocular infections in a study on school children in Delhi5. S. pneumoniae is also the cause of community acquired bacterial pneumonia, a substantial proportion of bacterial meningitis, otitis media and sinusitis worldwide6. There are more than 90 serotypes of S. pneumoniae described till date8. Of these, only a limited number of serotypes are responsible for majority of the infection, against which the currently available 23 valent capsular polysaccharide vaccine is designed6,7. Some of the serotypes involved in eye infections may be different from those associated with systemic infections 8. Moreover up to 77 per cent of healthy individuals including children carry S. pneumoniae as normal flora in the nasopharynx9,10. Due to the anatomical proximity of the eye to nasopharynx it is plausible that some of the commensal serotypes may be involved in some of the ocular infections. We studied 61 well characterized isolates of S. pneumoniae (38 from various ophthalmic infections, 9 from systemic infections and 14 commensal isolates from normal nasopharynx) for in vitro antimicrobial susceptibility pattern and serotype determination by co-agglutination (COA) method. Material & Methods Isolation and characterization of Streptococcus pneumoniae: Thirty-eight consecutive isolates of
S. pneumoniae ophthalmic isolates with no selection bias included in this study were from patients attending the outpatient department of Dr Rajendra Prasad Ophthalmic Centre for Ophthalmic Sciences, All India Institute of Medical Sciences (AIIMS), New Delhi from January 2002 to June 2003. The clinical diagnoses were; dachryocystitis: 28 [18 were
