[Antimicrobial susceptibility and serotype distribution of pneumococci strains isolated from meningitis patients]

Abstract

Treatment of life threatening pneumococcal infections such as meningitis has recently become problematic due to the emergence of antibiotic resistant strains. Antimicrobial susceptibility data usually derived from the studies that included all clinical pneumococcal isolates. However, resistance patterns of this microorganism isolated from meningitis cases in our country are not exactly known. The aim of this study was to determine the antimicrobial susceptibility and serotypes of Streptococcus pneumoniae strains isolated from meningitis cases. This retrospective study was designed in three university hospitals in Turkey and 72 pneumococci isolated from patients with meningitis were evaluated. In this study disk diffusion test and E-test methods were used to determine the susceptibility of pneumococci to some antibiotics. All S. pneumoniae isolates were serotyped using Quellung reaction. Although resistance for oxacillin was found by disc diffusion method in 11 isolates, only six of them were found to be resistant by E-test. By the latter procedure, no resistance was recorded against ceftriaxone and meropenem, while chloramphenicol resistance was found as 1.4%. In our study, erythromycin, ciprofloxacin and levofloxacin resistance were 2.8%, TMP-SMX resistance was 26.4%, while no vancomycin resistance was detected by disk diffusion. In evaluation of 72 pneumococci, we found 16 different serotypes and four isolates could not be serotyped. The serogroup 23 (n: 19) was the most common one followed by serotype 19 (n: 9) and serotype 14 (n: 7). Of six resistant isolates, three pneumococci were serogroup 23 and the remaining were from three different serotype/serogroups 11, 14 and 19. As a result penicillin resistance in pneumococci isolated from meningitis was low and there was no resistance to ceftriaxone. It seems that ceftriaxone is an appropriate choice for empirical treatment of meningitis in our patients. These findings also revealed that pneumococcal polysaccharide capsule vaccines in use cover most of the invasive pneumococcal serotypes.