Study of beta lactamase activity of Staphylococcus aureus isolated from healthy nasal carriers and hospital isolates.

Staphylococcus aureus (n=84) isolated from the nostrils of a healthy population from Kathmandu and from the infectious cases (n=100) from Tribhuvan University Teaching Hospital, Kathmandu, Nepal were tested from May 1996 to March 1997 in Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal by microbiological and chemical methods to find out their beta lactamase activity. Among the healthy population, in domiciliary conditions 21.4% of the isolates were found beta lactamase producers. The occurrence of beta lactamase producing S. aureus was greater among female (27.0%) than among male (17.0%), however it was not significant (X2 = 1.2309, P > 0.05). The occurrence of the same was observed high among 40 and above age groups (66.7%) and 0-9 age group (60.0%), however no association with any particular age group was observed (X2 = 16.8674, P > 0.05). The b lactamase activity of S. aureus hospital inpatients isolates was 75.0% showing high occurrence of b lactamase activity in hospital isolates compared to S. aureus isolates from healthy carriers (X2 = 52.4113, P < 0.001). No association of beta lactamase positive hospital isolates with gender (X2 = 0.2158, P > 0.05) and age group (X2 = 1.5522, P > 0.05) was observed. This study shows that the prevalence of beta lactamase positive S. aureus was greater in hospital cases than in nasal carriers in domiciliary condition indicating the requisition of further study in this field.