Previous antibiotic consumption and other risk factors for carriage of penicillin-resistant Streptococcus pneumoniae in children.

As part of the South Swedish Pneumococcal Intervention Project, aimed at reducing the spread of penicillin-resistant pneumococci with MICs for penicillin G > or =0.5 mg/l (PRP), all patients in Malmöhus county, southern Sweden, with a culture positive for PRP were followed up by means of repeated nasopharyngeal cultures until PRP-negative. If a child carrying PRP attended a day-care centre, nasopharyngeal cultures were obtained from the other children and staff. All children screened for PRP carriage in 30 day-care centres with an identified index case were included in the analysis, and several outcome variables (antibiotic consumption during the preceding 6 months, previous health and social situation) were assessed in relation to the end-point PRP carriage. Of 1036 children, 128 were found to be PRP carriers and 908 were PRP non-carriers. The PRP carriers had higher antibiotic consumption, were younger and were more often of male sex than the non-carriers (P<0.05). Consumption of antibiotics during the preceding 6 months was noted in 53% of carriers and 45% of non-carriers (relative risk 1.20, 95% confidence interval 1.01-1.43). When adjusting for age, gender and day-care centre attendance, recent consumption of cotrimoxazole (trimethoprim/sulfamethoxazole) emerged as an independent risk factor for PRP-carriage (relative risk 3.48, 95% confidence interval 1.10-11.07). The PRP-carriage rate in three day-care centres with high cotrimoxazole consumption was significantly higher (24%) than in the other day-care centres (10%) (P<0.005). The results indicate that measures aimed at reducing consumption of antibiotics in general, and cotrimoxazole in particular, may decrease the incidence of penicillin resistance, but such measures are, by themselves, probably not sufficient to halt the spread.