Characterization of B-lactamase genes in eschericia coli isolated from broilers

الملخص EN

Due to intensive use of β-lactam drugs as therapeutic agents and growth promoting the β-lactam resistant is developed,and it is primarily developed by β-lactamases .

therefore ,the objective of this study was to characterize β-lactamase genes in E.

coli isolated from broilers.

A total of 105 sampels isolated from broilers from Gharbia governorates ,28 isolates were positive for E.coli (26.6%), 15 isolatas were randomly taken and they serogrouped to 7 serotypes (O 55, O78, O 125, O126, O 157, O119 :H6 ,and O1:H7) .All isolated strains showed multidrug resistance phenotypes particularly against amoxicillin, erythromycin, doxycyclin, norfloxacin, and colistin sulphate respectively, PCR for the detection of β-lactamase genes in isolated strains showed that , all isolates contain β-lactamase genes, 5 isolates contain bla TEM 5 (50%), 2 isolates contain bla CTX-M 2 (20%), 3 isolates contain bla OXA 3 (30%), 2 isolates contain bla SHV 2 (20%), 1 isolates contain both bla TEM and bla OXA, 2 isolate contain both bla TEM and bla CTX-M and 1 isolate contain three gens bla TEM , bla SHV, and bla CTX-M .

E.

coli is a common inhabitant of the human and animal gut and it considered an indicator of fecal contamination in food.

β-lactams are widely used in human and veterinary medicine to treat human and animal infections (Livermore, 1998).

This widespread use of antibiotics could be associated with the selection of antibiotic resistance mechanisms in pathogenic and nonpathogenic isolates of E.

coli (Sunde and Sorum, 1999).

Resistance to β-lactams in Enterobacteriaceae is mainly due to the production of β-lactamases which may be encoded either chromosomally or on plasmids (Bradford, 2005).

β-Lactamases are enzymes responsible for many failures of antimicrobial therapy because of the hydrolysisof β-lactam antibiotics to inert and ineffective agent ,The first of these enzymes was recognized by Abraham and Chain in 1940.

Resistance to extended-spectrum β-lactams has been associated with the production of broad-spectrum β-lactamases such as extendedspectrum β-lactamases (ESBLs) (Batchelor et al., 2005a).

Many types of - lactamases have been described ,but TEM, SHV, OXA, CMY, and CTX-M type - lactamases are the most common in gram-negative bacteria (Bradford,2001), Also all groups of - lactamases were identified including bla TEM-1, bla TEM-104, bla CMY-2, bla OXA-30, bla CTXM15, and bla SHV-2 (Ahmed, et al, 2013), Furthermore,bla TEM, blaOXA, and bla CTX-M were reported in E.

coli strains isolated from broiler chickens and turkeys in the United Kingdom (Randall et al., 2011), while blaTEM and bla SHV were identified in APEC strains isolated from poultry in Australia (Obeng et al., 2012).