Background and Objectives: Resistance to a wide variety of common antimicrobials has made the proliferation of Extended spectrum β-lactmase (ESBL) producing strains a serious global health concern that has complicated treatment strategies. The high proportion of ESBL producers among the Enterobacteriaceae and the complex molecular epidemiology with diverse types of ESBL genes are alarming. This study was undertaken to identify ESBL production in various Gram negative bacilli isolated and to further characterize ESBL producers among Escherichia coli and Klebsiella spp by PCR, which were initially screened by phenotypic method. Materials and Methods:A total of 722 isolates of Gram negative bacilli were isolated. Presence of ESBL positivity was detected using the double disk synergy test (DDST). Their antibiogram was studied. PCR analysis for β-lactamase (bla) genes of the family TEM, SHV and CTX-M was also carried out using designed primers in 20 ESBL isolates each of Escherichia coli and Klebsiella spp.Results: Among 722 Gram negative bacilli isolated 379 (52.49%) were ESBL producers. The major source of ESBL producers were respiratory tract samples, highest ESBL production was observed in Klebsiella sp. (67.04%). Resistance to multiple classes of antibiotics was observed among ESBL producers. Among ESBL producing genes prevalence of bla-CTX-M (82.5%) was highest, followed by bla-TEM (67.5%) and bla-SHV (57.5%) in the present study. The frequency of ESBL producing strains among clinical isolates has been steadily increasing. Advance drug resistance surveillance and molecular characteristics of ESBL isolates is necessary to guide the appropriate and judicious antibiotic use.

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Background: Rapid and accurate detection of methicillin resistant Staphylococcus aureus (MRSA) is an important role of clinical microbiology laboratories to avoid treatment failure. The aim of this study was to compare conventional methods against the cefoxitin disc diffusion method to determine the best phenotypic method. Methods: Study was carried out in the Department of Microbiology, National Institute of Medical Sciences & Research, Jaipur (India), between July 2016 – December 2016. The methods included were Oxacillin E-test MIC, Oxacillin screen agar, Oxacillin disk diffusion, Cefoxitin disk diffusion and CHROMagar- MRSA methods. Antimicrobial susceptibility performed as per CLSI guidelines.Results: Out of 142 isolates of S. aureus, fifty three (37.32%) strains of MRSA were isolated from clinical specimen. E-MIC test was selected as gold standard method. The sensitivity and specificity of Oxacillin screen agar and CHROMagar-MRSA were same 98.07% and 97.80%, respectively. The sensitivity and specificity of oxacillin disk diffusion were 94.23% and 98.89%. Fifty three strains of S. aureus were MRSA by cefoxitin disk diffusion method and Oxacillin Ezy MIC test. The sensitivity and specificity of cefoxitin disk diffusion method and Oxacillin Ezy MIC method was 100% and 100% respectively. All isolates including MRSA were susceptible to Vancomycin and Linezolid. Conclusions: All phenotypic methods had high sensitivity and specificity for detection of MRSA. However, cefoxitin disk diffusion method in comparison to other methods had higher sensitivity and specificity.

Staphylococcus aureus is one of the most common human pathogens with ability to cause a wide range of infections. On an average 20-40% of the adults are carriers of S. aureus in the anterior nares. [1] The emergence of community-acquired (CA) and hospital acquired (HA) methicillin resistant S. aureus (MRSA) has led to increasing in cases of invasive infections. [2,3] In 1965 first case of MRSA infection recorded in Australia, (Sydney) [4,5] and in 1980 first case of a CA-MRSA infection in the United States was reported. Both HA-MRSA and

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