Rama Sikka, Shuchi Mehra, Kausalya Raghuraman, Uma Chaudhary


Introduction: Infections due to Gram-negative bacilli are on rise world over. The rampant use of broad-spectrum antibiotics can lead to colonization with resistant strains with an increase in morbidity, mortality, and significant economic loss. Multidrug-resistant organisms (MDRO) by virtue of production of various β-lactamases confer resistance to many classes of antibiotics, particularly cephalosporins.

Material and methods: The present study was conducted over a period of one year on a total of 100 non repetitive MDR isolates of Gram-negative bacilli of family Enterobacteriaceae. All isolates were identified by standard microbiological techniques and antimicrobial susceptibility pattern was determined. American Type Collection (ATCC) strain viz. E. coli. ATCC 25922 was employed as a control strain.Isolates showing reduced susceptibility to third generation cephalosporins were tested for ESBL production as per CLSI guidelines. Isolates showing reduced susceptibility to cefoxitin were screened by AmpC disc test.Isolates showing reduced susceptibility to carbapenems were tested for MBL production by ceftazidime-EDTA disc test.

Results: The prevalence of ESBL, AmpC and MBL was 70%, 39% and 45% respectively. ESBL production along with MBL production was seen in 19% of the  isolates. ESBL production along with AmpC production was seen in 12% of the isolates. MBL production along with AmpC production was observed in 10% of the isolates. Coproduction of all three β-lactamases was observed in 9% of the isolates.

Conclusion: The high prevalence of beta-lactamases emphasizes the need for an early detection  by simple screening methods, which can help in providing an appropriate antimicrobial therapy and in avoiding the development and the dissemination of these multidrug resistant strains.



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