EVALUATION OF PENICILLIN SUSCEPTIBILITY IN CLINICAL ISOLATES OF STREPTOCOCCUS-PNEUMONIAE OXACILLIN-RESISTANT

Antibiotic resistant pneumococci have been reported from all continent s. Because of the importance of pneumococci in the aetiology of life-t hreatening diseases, the screening for penicillin resistance with oxac illin disc on all clinically significant isolates is suggested. Howeve r, discrepancy between the determination of penicillin resistance by o xacillin disc diffusion and the determination of penicillin minimum in hibitory concentration (MIC) has been reported. On this basis we have examined seven strains of Streptococcus pneumoniae isolated from patie nts recovered for the exacerbation of chronic bronchitis which were ox acillin-resistant. The assay of penicillin MICs showed that three isol ates were moderately resistant to this agent, while four isolates resu lted sensitive to penicillin as well as to cefotaxime. These results s uggest that a further evaluation of penicillin MIC should be performed on those strains of S. pneumoniae resulting oxacillin-resistant.