Resistance patterns of Streptococcus pneumoniae isolated from the upper respiratory tract of persons attending various clinics of a University Teaching Hospital in Lagos, Nigeria - a preliminary study

Abstract

The upper respiratory carriage rate, serotypes and resistance patterns of Streptococcus pneumoniae in persons attending four clinics of the Lagos University Teaching Hospital (LUTH) were determined. Nasal swab specimens were collected from a total of 372 persons, 175 of whom were males and 177 were females. Their ages ranged from 14 weeks to 65 years. The upper respiratory carriage rate found in the total population of both adults and children was 9.9%, but the rate was highest in children less than 5 years (18.6%). Among the 17 isolates that were available for serotyping, there was no significant serotype, though resistant serotypes like 23F. 19F. 6A and I4 were identified. Initial oxacillin screening for penicillin resistance revealed that 12 out of 36 isolates were clearly sensitive, but combined with the result of Etest, penicillin resistance was found to be 6.8%. Susceptibility testing by disc diffusion revealed that 80.5% of isolates were sensitive to ceftriaxone and 94.4% to chloramphenicol. Sixty one percent were sensitive to erythromycin while 94.4% were resistant to co-trimoxazole and 80.5% to tetracycline. Except for amoxicillin and cefotaxime which showed high activity, sensitivity pattern by Etest was found to be similar to that of disc diffusion. The result of this study makes it possible to formulate hypothesis for a larger study. In this study. the carriage rate of S. pneumonia probably ranged from 2.6% to over 18.6% depending on the study population. If the limitations of this study are excluded in a larger study, the rate most likely will be higher. Also, penicillin resistance in carriage strains would be up to 6.8%, probably higher, but may be intermediate, so penicillin could still be useful for treatment of pneumonia and probably otitis media, but not meningitis. There is reason to watch out for increased resistance to penicillin, cephaloporin and erythromycin. Most pneumoeoccal isolates would likely be resistant to tetracycline and co-trimoxazole.

African Journal of Clinical and Experimental Microbiology Vol. 7(2) 2006: 89-97