Prevalence of penicillin-resistant viridans streptococci in healthy children and in patients with malignant haematological disorders.

The prevalence of penicillin-resistant viridans streptococci was studied in healthy children and in paediatric and adult patients with leukaemia to determine whether the frequent presence of penicillin-resistant streptococci in the oral cavity of children with leukaemia is the result of antibiotic therapy. Twenty of the oral swabs from 50 healthy children who had not received antibiotics in the three months prior to sampling yielded viridans streptococci that could be cultured on blood agar containing 2 micrograms/ml benzyl-penicillin. In 11 of the 20 cases the streptococci were resistant to penicillin (MIC > or = 4 micrograms/ml). This prevalence is significantly higher than that found in adult leukaemia patients (40% vs. < or = 5%) but is about the same as that found in paediatric patients with leukaemia. The high prevalence of penicillin-resistant streptococci in the paediatric age group should be considered when selecting therapy and prophylaxis, especially when the risk of infection with one of these cocci is enhanced.