Detection of Enterobacteriaceae producing CTX-M extended spectrum beta-lactamases from a tertiary care hospital in south India.

A total of 23 clinical isolates (15 Escherichia coli and 8 Klebsiella pneumoniae), resistant to cefotaxime and ceftazidime recovered during 2002 and 2003, were investigated for production of CTX-M extended spectrum beta-lactamase (ESBL) by phenotypic and molecular methods. The presence of ESBL was tested by NCCLS phenotypic confirmatory test using cephalosporin/clavulanate combination discs and E-test ESBL strips. Determination of MIC of cefotaxime and ceftazidime was done with and without the presence of clavulanic acid by agar dilution technique. Polymerase chain reaction revealed the presence of CTX-M type ESBLs in 19 isolates. Further sequencing resulted in identification of CTX-M-15 ESBLs. This is the first report identifying CTX-M type ESBL from clinical isolates of E. coli and K. pneumoniae from a tertiary care hospital in south India.

Prevalence and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus: a multicentre study.

PURPOSE: Methicillin resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen. We report the prevalence and antibiotic susceptibility pattern of MRSA in major southern districts of Tamilnadu. METHODS: A total of 7172 clinical specimens and 1725 carrier screening samples were collected from different centers and subjected to MRSA screening using conventional microbiological methods. Subsequently the antibiotic sensitivity test was performed for the confirmed MRSA isolates. RESULTS: Out of 906 strains of S. aureus isolated from clinical and carrier samples, 250 (31.1%) and 39 (37.9%) were found to be methicillin resistant respectively. Almost all clinical MRSA strains (99.6%) were resistant to penicillin, 93.6% to ampicillin, and 63.2% towards gentamicin, co-trimoxazole, cephalexin, erythromycin, and cephotaxime. All MRSA strains (100%) of carrier screening samples had resistance to penicillin and about 71.8% and 35.9% were resistant to ampicillin and co-trimoxazole respectively. Multidrug resistance was observed among 63.6% of clinical and 23% of carrier MRSA isolates. However, all strains of clinical and carrier subjects were sensitive to vancomycin. CONCLUSION: The determination of prevalence and antibiotic sensitivity pattern of MRSA will help the treating clinicians for first line treatment in referral hospitals.