Pneumococcal infections in Trinidad: Patterns of antimicrobial susceptibility: 1994-2002

Abstract

Antimicrobial susceptibilities of 156 Streptococcus pneumoniae strains isolated from 1994 through 2002 were studied. Of this total, 38.7, 26.3, 16.7, 8.9, and 9.6% were recovered from patients with bacteremia, pneumonia, otitis media, sinusitis, and meningitis, respectively. All S. pneumoniae strains were fully susceptible to amoxicillin-clavulanic acid and ampicillin, with 9.0 and 2.6% being resistant to penicillin and ceftriaxone, respectively. The ratios of resistant strains to tetracycline, co-trimoxazole, and chloramphenicol were 73.7, 69.3, and 63.5%, respectively. Approximately 90% of strains remain sensitive to erythromycin. A high prevalence of resistance to the penicillins and cephalosporins, does not exist in Trinidad, although a trend toward such a pattern appears to be developing. The most frequent serotype was 14 (37.8%), followed by 6B (20.0%), 23F (10.3%), and 4 (6.4%), and all were recovered from children. The other serotypes accounted for <6% of the total isolates. All penicillin- and ceftriaxone-resistant strains belonged to serotype 14 (MIC ≥ 2 μg/ml and ≥ 4 μg/ml), respectively. Identifiable risk factors for resistant isolates included the prevalence of otitis media and sinusitis among children treated inadequately with oral cephalosporins; the ease of obtaining antibiotics without a prescription at many pharmacies; and the indiscriminate prescribing of antibiotics by general practitioners.