Original Articl PREVALENCE OF AMPC Β-LACTAMASES IN CLINICAL ISOLATES OF E. COLI FROM A TERTIARY CARE RURAL HOSPITAL e DARDI CHARAN KAUR 1 , JAISHREEE S PURI 2 , SANDHYA S KULKARNI 3 , ANJALI JAYAWANT Assistant Professor, Department of Microbiology, MIMER Medical College, Talegaon Dabhade, Pune Email: 4 Received: 22 Dec 2014 Revised and Accepted: 25 Jan 2015 charan13@rediffmail.com ABSTRACT Objective: Organisms over expressing AmpC (Ambler Class C) β-lactamases are of clinical concern because they restrict therapeutic options causing treatment failures and are increasing in occurrence worldwide. So the present study was to undertaken with the aim to know the prevalence of plasmid mediated AmpC and inducible AmpC β-lactamases in clinical isolates of E. coli in our tertiary care rural hospital. Methods: 74 cefoxitin resistant E. coli isolates were tested for AmpC production by combined disc diffusion test and disk approximation test. Results: Out of 74 cefoxitin resistance E. coli isolated from various clinical specimen 25(33.78%) showed AmpC β-lactamases production. PMABL was seen in 22(29.73%) and inducible AmpC in 3(4.05%). Among 25 AmpC producing E. coli, 8(32%) were from urine, 5(20%) from miscellaneous, 4(16%) from sputum and 12% respectively from stool and Pus and in Blood 2(8%). Age-wise higher distribution of AmpC β-lactamase was in an age group below 1yr (44.44%) and in age group of 20-39yrs (40%). The higher distribution of Conclusion: The overall prevalence of 10.50% AmpC β-lactamase in E. coli and Multidrug resistance is a matter of concern. So identification of AmpC may help in formulating the hospital infection control committee decreasing the selective antibiotic pressure. AmpC β lactamases producer from Medicine, Obgy, ICU(20% respectively) paediatric 16%,surgery 8%, TB 12% and lower from OPD(4%). In our study, multidrug resistance has been observed among the PMABL producing strains. Higher resistance was seen in gentamicin 22(88%), ciprofloxacin 23(92%), ceptazidime 25(100%), cefaclor 25(100%). Whereas PMABL isolates was susceptible to tigecycline (100%), meropenem (92%), amikacin(60%). Keyword: Cefoxitin resistance, Escherichia coli, AmpC β lactamases, Combined disc diffusion test and Disk approximation test. INTRODUCTION Gram-negative bacteria pose a therapeutic problem not only in the hospital settings, but also in the community as they have acquired resistance to multiple antibiotics. Organisms over expressing AmpC β-lactamases are of clinical concern because they restrict therapeutic options causing treatment failures and are increasing in occurrence worldwide. AmpC β-lactamases belong to Ambler class C or Group I of Bush’s functional classification, they confer resistance to cephalosporins in the oxyimino group (cefotaxime, ceftriaxone, ceftazidime), 7 alpha methoxy cephalosporins (CX) and are not affected by available β-lactamase inhibitors (clavulanate, sulbactam) [1]. Resistance to expanded-spectrum cephalosporins may develop through the expression of chromosomally encoded class C β- lactamases, also known as AmpCβ-lactamases. These are of two types of Amp C-chromosomally mediated (inducible or constitutive) or plasmid mediated non-inducible [2]. Plasmid mediated AmpC β-lactamases (PMABLs) was first reported in 1988 and have evolved by the movement of chromosomal genes on to plasmids and are found in Escherichia coli, Klebsiella pneumoniae, Salmonella spp, Proteus mirabilis, Citrobacter freundii, Enterobacter aerogenes which confer resistance similar to their chromosomal Amp C β-lactamases and are typically associated with broad multidrug resistance [3, 4]. The Amp C β-lactamases have been named based on their resistance to cephamycin (CMY), cefoxitin (FOX), moxalactam (MOX), latamoxef (LAT); site of discovery such as Miriam Hospital in Providence (MIR) or Dhahran Hospital in Saudi Arabia (DHA) or name of the source patient, Bilal (BIL). Currently there are 43 CMY alleles, 7 varieties of FOX, 3 varieties to ACT and MOX, 2 varieties of DHA and 4 varieties of ACC, LAT and MIR each [2]. Amp C genes are grouped into six families based on the similarities in the gene sequence and/or origin as CIT (origin Citrobacter freundii), EBC (origin Enterobacter cloacae), DHA (origin Morganella morgannii), ACC (origin Hafnia alvei, FOX (origin unknown) and MOX (origin unknown) [2]. Plasmid-mediated AmpC enzymes have been described from diverse geographic areas, including the United Kingdom, the United States, and Asia [5-8]. In India, prevalence of AmpC β-lactamases in E coli has been reported from 3.3% to37.5% [9, 10]. Reduced susceptibility to cefoxitin in the Enterobacteriaceae may be an indicator of AmpC activity, but cefoxitin resistance may also be mediated by alterations to outer membrane permeability [11]. Differentiation between cefoxitin-resistant AmpC producers from cefoxitin-resistant non-AmpC producers could guide treatment options (i.e. extended spectrum cephalosporins for cefoxitin- resistant non-AmpC producers and carbapenems for the cefoxitin- resistant AmpC producers). Differentiation between them would prevent the unnecessary usage of cephalosporins and carbapenems resulting in the selective pressure driving the AmpC or plasmid mediated class A carbapenem resistance gene propagation [12]. Detection of AmpC β-lactamases is a challenge to clinical microbiologists. Currently, there are no CLSI-recommended guidelines to detect AmpC β-lactamases [13]. Several phenotypic methods for detection methods of AmpC β-lactamases are described. AmpC screening using disk diffusion, combined disc diffusion test, modified three-dimensional test. But phenotypic tests do not differentiate between chromosomal AmpC genes and AmpC genes that are carried on plasmids. Hence, genotypic characterization is considered as the gold standard [4]. Coudron et al. Used the standard disk diffusion breakpoint for cefoxitin (CX) (zone diameter<18 mm) to screen isolates and used a 3D extract test as a confirmatory test for isolates that harbour AmpC β-lactamases [3]. The detection of plasmid mediated Amp C resistance is important to improve the clinical management of infection and to provide sound epidemiological data [12]. Although reported with increasing frequency the true occurrence in different organisms remains unknown. International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 7, Issue 6, 2015 Innovare Academic Sciences