Streptococcus pneumoniae: a study of strains isolated from cerebrospinal fluid

To determine the frequency of capsular serotypes and the antimicrobial susceptibility of strains of Streptococcus pneumoniae, as well as to provide recommendations on the use of available vaccines and antimicrobial drugs.

In this retrospective study, standard procedures were followed to identify, serotype, and determine bacterial susceptibility to penicillin, cefotaxime, and vancomycin. Pneumococcal strains were isolated from the cerebrospinal fluid (CSF) of patients admitted to nine public and three private hospitals in Distrito Federal, Brazil, between January 1995 and December 2004. Identification and antimicrobial susceptibility tests were carried out at the Central Laboratory of Public Health (Laboratório Central de Saúde Pública). Serotyping was performed at Instituto Adolfo Lutz.

A total of 232 pneumococcal strains were isolated, including 126 (54.31%) strains from male patients. Patients had an age range of 0 to 62 years and were distributed into four age groups: 0 to 5, 6 to 17, 18 to 50, and above 50. From the 36 distinct serotypes identified, eight were more prevalent: 14, 6B, 18C, 5, 19F, 23F, 9V, and 6A. The oxacillin test identified 67 penicillin-resistant strains, out of which 47 were confirmed by the E test as having intermediate level of resistance. None of the strains exhibited high-level resistance.

Pneumococcal resistance to penicillin has gradually increased over the last 10 years in Distrito Federal. Serotypes more frequently isolated in the 0 to 5 years age group were the same involved in penicillin-resistance, all of which are covered by the 7-valent vaccine.