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International Journal of Recent Trends in Science and Technology, ISSN 2277-2812 E-ISSN: 2249-8109

Volume 9, Issue 3, January 2014 pp 358-360

Research Article

Detection of AmpC β-Lactamases among Gram Negative Clinical Isolates

Vijaya Shivanna¹, Achut Rao²

¹Assistant Professor, Department of Microbiology, Adichunchanagiri Institute of Medical Sciences

Balagangadhara natha Nagara,Mandya Dist, Karnataka, INDIA.

Academic Editor : Dr. Aher K. R.

Background and Objectives: AmpC β-lactamases confer resistance to a wide variety of β-lactam antibiotics including cephamycins such as cefoxitin and cefotetan, narrow and broad spectrum cephalosporins, aztreonam and are poorly inhibited by β-lactamase inhibitors such as clavulanic acid. The present study was undertaken to determine the occurrence of AmpC enzyme producing Gram negative clinical isolates at Navodaya Medical College, Raichur.Materials and Methods: 200 non-repeat Gram negative clinical isolates from various samples were screened for AmpC β- lactamases by using Modified disc Approximation method. The “Screen positive” isolates were detected for AmpC β-lactamase by Modified three-dimensional enzyme extract test, AmpC disk test, and phenyl boronic acid test.Results: Out of the 200 Gram negative isolates, 87 (43.5%) isolates were screened to be positive and 10 (5%) isolates were inducible AmpC producers. Of these 97 isolates subjected to confirmatory tests, 74 (37%) were harbouring AmpC enzymes. Majority of AmpC positive isolates were E.coli (20.5%), K.pneumoniae (5.5%) and Acinetobacter spp. (3.5%).Conclusion: Phenyl boronic acid test is the simple and practical method for the detection of AmpC in routine clinical microbiology laboratories. Plasmid-mediated AmpC β-lactamases have been associated with false in vitro susceptibility to cephalosporins. Thus, the type of β-lactamase produced by the organism should be detected along with the antibiogram for appropriate treatment of the patient.