[Study of the sensitivity to antibiotics and genes for macrolide resistance to streptococcus pneumoniae isolated in a pediatric tunisian setting]

ABSTRACT

Streptococcus pneumoniae is often incriminated in invasive and non invasive severe infections. Therapeutic choice becomes difficult these last years because of the spread of resistant strains worldwide, particularly pneumococci non susceptible to penicillin [PNSP]. The aim of our study was to determine the epidemiological characteristics of S. pneumoniae strains isolated in children, the antimicrobial susceptibility and the genes involved in macrolide resistance. We studied 422 none duplicated S. pneumoniae strains isolated from 2000 to 2008 in our laboratory. Invasive strains were essentially isolated from cerebrospinal fluid [50.2%] and blood culture [34.4%], whereas the majority of non invasive ones were isolated from pulmonary samples [76.5%]. Two hundred and twenty five isolates [53.3%] were with reduced susceptibility to penicillin, 12.8% of them had a high level of resistance. For the other beta-lactams, 29.6% and 15.1% of strains were with reduced susceptibility to amoxicillin and cefotaxim respectively. Erythromycin and lincomycin resistance concerned 66.6% and 59.6% respectively. Among the 66 strains studied by PCR 62 harbored ermB gene, 3 harbored mefA gene and one strain harbored both of them. PNSP strains were much more resistant to the different tested antibiotics than strains susceptible to penicillin. This fact complicates therapeutic choices and justifies the need of resorting to effective anti-pneumococcal vaccine to prevent pneumococci infections