Penicillin-Nonsusceptible Streptococcus pneumoniae in Malmö, Sweden. Aspects of Epidemiology, Microbiology and Genetics

Sammanfattning: S. pneumoniae is a major cause of common diseases such as acute otitis media and pneumonia, as well as more serious illnesses like septicemia and meningitis. The increasing level of resistance in pneumococci threatens to change the tradition of treating common respiratory infections with narrow-spectrum penicillin. In the city of Malmö the proportion of penicillin nonsusceptible S. Pneumoniae (PNSP) increased to about 10% at the beginning of the 1990s. In Paper 1 we showed that the emergence of PNSP in Malmö in 1994?1995 was caused by several different clones. Many studies have suggested that day care centers constitute an ecological reservoir of PNSP clones. Among children attending DCCs in the Malmö region, 42% were carriers of S. pneumoniae, and 13% of those children carried PNSP (Paper 2). We found no evidence that the minor variations observed in building or hygiene standards at the DCCs had a significant impact on pneumococcal carriage, but younger age of the children was significantly associated with carriage of pneumococci. The incidence of PNSP cases per 1,000 children was positively correlated with the prescribing of antibiotics in Malmö (Paper 3). Prescribing of antibiotics was positively correlated with the level of income in different residential areas in Malmö. We also observed relatedness of pbp genes in both susceptible and nonsusceptible pneumococci, and horizontal transfer of pbp genes may be one explanation for the spread of resistance to penicillin in pneumococci in Malmö (Paper 5). In conclusion, the proportion of PNSP in Malmö has remained stable since the rapid increase in these bacteria seen in the mid 1990s, despite a steady decrease in the prescribing of antibiotics and an ongoing intervention program (Paper 4).