Penicillin and vancomycin tolerance among clinical isolates of Streptococcus pneumoniae in Hong Kong

Objective. To determine the prevalence of penicillin and vancomycin tolerance in clinical isolates of Streptococcus pneumoniae. Design. Laboratory testing of 50 consecutive clinical isolates. Setting. District hospital, Hong Kong. Patients. Fifty patients with pneumonia or meningitis who were admitted to a district hospital in Hong Kong between August and October 2002. Main outcome measures. Lysis, as assessed by loss of optical density at 4 hours at 540 nm, and reduction in viable count expressed as the log of the number killed ('log kill') after exposure of cultures to 10 times the minimum inhibitory concentration of penicillin and vancomycin. Results. Of the 50 isolates, five (10%) were tolerant to penicillin and one (2%) was tolerant to vancomycin. Conclusion. This is the first report of vancomycin tolerance in Streptococcus pneumoniae in Hong Kong. Because vancomycin tolerance is associated with clinical failure in the treatment of pneumococcal meningitis, increased monitoring for resistant strains of organisms is suggested.