Changing pattern of nasal carriage of staphylococcus aureus in undergraduate medical students.

Staphylococcus aureus is the most common pathogen in nosocomial infections (4-6,17,19). Nasal carriage of Staphylococcus aureus is now considered a well defined risk factor for subsequent infections in various groups of patients (5,8,12,19). Nasal carriage of the pathogen among hospital personnel is an important source of nosocomial infection (1.3.18). Very few dedicated studies have investigated the nasal carriage state among medical students (3,18,21). Incidence of Staphylococcus aureus in the nasal flora of medical students, with or without varying degrees of clinical exposures were determined in our study. Nasal cultures from these students demonstrated a significantly increasing rate of colonization of Staphylococcus aureus with increased clinical exposure and also a corresponding increase in Methicillin resistance.

Neomycin robertson’s cooked meat medium (N.RCM) for the selective isolation of anaerobes.

As Robertson’s cooked meat medium (RCM) promotes the simultaneous multiplication of facultative anaerobes along with anaerobes, it may be interfered with the isolation rate of anaerobes. In the present study RCM was made selective to overcome this difficulty by the incorporation of Neomycin. The efficacy of modified RCM was evaluated by growing stock cultures of various anaerobes and aerobes well as by inoculating clinical specimen directly and comparing the results with routine RCM. Among the 160 stock cultures of aerobes 8 of the 28 neomycin resistant aerobes grew in N.RCM but none of the 132 neomycin sensitive aerobes. Out of the 150 clinical samples tested in the study,77 anaerobes and 97 aerobes were isolated from routine RCM whereas 89 anaerobes and 8 Neomycin resistant aerobes from NRCM (i.e. NRCM inhibited 91.7% of aerobes and gave an increased yield of 13.5% anaerobes).These findings suggest that NRCM can be employed to suppress the aerobes and at the same time to enhance the isolation of anaerobes.