Detection of Inducible AmpC β-Lactamase-Producing Gram-Negative Bacteria in a Teaching Tertiary Care Hospital in North India

AmpC β-lactamase enzymes confer resistance to a wide variety of β-lactam antibiotics, except carbapenems. AmpC β-lactamase-producing bacteria are known to be causative pathogens of nosocomial infections, which are difficult to be treated. Hence, this study was aimed out to determine the prevalence of AmpC β-lactamase enzyme production among Gram-negative bacteria. A total of 500 multidrug-resistant isolates were tested for cefoxitin susceptibility during a one-year period of study. All the isolates were tested for AmpC β-lactamase production by both the disk approximation and AmpC disk methods. The isolates positive for AmpC β-lactamase production were also tested for antimicrobial susceptibility by the disk diffusion method. AmpC β-lactamase production was noted in 101 (20.20%) isolates. All the isolates were 100-percent susceptible to imipenem and meropenem with variable susceptibilities to other antimicrobial agents. (J Infect Dis Antimicrob Agents 2008;25:129-33.) Uma Chaudhary, M.D., FIAMS*, Ritu Aggarwal, M.D.* Sanjeev Ahuja, M.D.** *Department of Microbiology, Pt. B.D. Sharma, PGIMS, Rohtak, Pt. B.D. Sharma, PGIMS, Rohtak, India. **Senior Resident, Super Specialty Hospital Janakpuri, New Delhi, India. Received for publication: July 4, 2008. Reprint request: Dr. Ritu Aggarwal, M.D., H. No. 717, Sector-1, HUDA, Rohtak-124001, Haryana, India. E-mail: [email protected]