Shagufta Hussain, Abdul Hannan, Ashok K Tanwani, Mushtaq A Khan.
Penicillin resistance in clinical isolates of Streptococcus pneumoniae and optimal in vitro methods for its detection.
Pak J Pathol Jan ;10(2):7-10.

Clinical isolates (n=264) of streptococcus pneumoniae (SP) obtained from cultures of nasopharyngeal swabs, sputum, blood, CSF and body fluids of clinically sick children at Children Hospital, Pakistan Institute of Medical Sciences, Islamabad, Pakistan were tested for their sensitivity to penicillin. In vitro susceptibility to penicillin was done by using 1 ug oxacillin disc and MIC determination, 46.21% isolates were found to be relative penicillin resistant (RPR) and complete or high resistance to penicillin was only 0.76%. Instead penicillin 10 units disc picked only 11.37% as RPR and did not pick up any highly resistant strain. Thus penicillin disc picked 35.6% strains as falsely sensitive, showing inability of penicillin disc to detect in vitro RPR and high resistance in pneumococci. In view of the serious life threatening infections caused by SP correct in vitro methods for detection of penicillin resistance are mandatory.

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