[Microbiological, clinical and epidemiological aspects of Streptococcus pneumoniae isolates recovered over two years].

Introduction: Streptococcus pneumoniae is the most frequent cause of non-hospital acquired pneumonia and meningitis in adults, and bacterial otitis media in children. Moreover, it causes a third of all acute sinusitis cases. Penicillin has been the treatment of choice for almost 50 years. Gradually, penicillin-resistant pneumococci have appeared throughout the world. Our aim was to investigate the epidemiology, pattern of resistance and serotypes of Streptococcus pneumoniae infection in our area.

Methods: Over a period of two years (May 1997-May 1999), Streptococcus pneumoniae strains were isolated in the Clinical Microbiology Unit of the University Hospital Virgen de la Victoria in Málaga, Spain. This is a 750-bed hospital covering a population of 407,480 inhabitants, and admitting 21,500 hospitalized patients per year. Streptococcus was identified by standard procedures: serotyping was done with the Quellung test and antibiotic susceptibility study by the disk diffusion method and E-test.

Results: Streptococcus pneumoniae infection was diagnosed in 170 patients during the years studied. The microorganism was isolated from samples of sputum (82), blood (43), aspirated bronchial fluid, cerebrospinal fluid (6), and exudates (7). Non-hospital origin was identified in 88% of cases. The mean hospital stay was 12 days and mortality was 12.4%. Some 45.9% of the isolated strains were resistant to penicillin and 20% to cefotaxime. We found 31 different serotypes, with 77% of the isolated strains belonging to 12 serotypes. Serotypes 19, 3 and 6B were the most frequent in non-hospital infection, whereas 9V and 23F were related with nosocomial infection. Penicillin-resistant strains of Streptococcus pneumoniae belonged to 19 different serotypes; 6B, 9V, 14, 19 and 23F were the most important.

Conclusions: As was expected, Streptococcus pneumoniae infections of mainly non-hospital origin in our area were characterized by elevated mortality and high-level resistance to penicillin. Immunosuppression was a predisposing factor.