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Published on December 2, 2014

described in BAM [10]. A quantity of 10gm of beef positivity of hemolysin test and Congo red binding sample was minced with the help of sterile scissors and assay observed was 3.60 percent. All 9 pathogenic E. mixed in 90 ml normal saline solution (pH 7.2) in screw coli isolates were subjected to antibiotic sensitivity test -5 against gentamycin, tetracycline and enrofloxacin. The cap bottle. Ten fold serial dilutions were made up to 10 zones of inhibition of antibiotic were recorded. The dilution in normal saline solution (pH 7.2). A quantity -3 -4 average zone of inhibition seen were gentamicin (20.00 of 0.1 ml inoculam from 10and 10dilutions was used ±1.49mm), enrofloxacin (18.22±3.58mm) and tetracycline by spread plate technique on Eosin Metheline Blue agar (11.44±2.04 mm). All 9 isolates were sensitive to (EMB) (Himedia Laboratories, Mumbai). Incubation was 0 gentamicin while 7 isolates showed resistance to enroflo- done at 37C for 24 hrs and colony counts were taken. xacin and Tetracycline. A complete sensitivity of all 9 Typical characteristics colony of E. coli on EMB agar isolates (100 percent) was observed against gentamicin. as greenish metallic sheen was enumerated and isolated. Identification of E. coli was done by biochemical test Discussion i.e IMViC, catalase, oxidase & nitrate reduction and In present study, very low percentage( 08.80 sugar fermentation and motility tests. [11]. percent) of E. coli was isolated. The findings of present In-vitro pathogenicity test of E. coli : In-vitro patho- study are in agreement with earlier reports [3,15]. genicity test of confirmed E. coli isolates was done by The E. coli counts are in the of range 6.85 to 7.40 log 10 heamolysis and Congo red binding assay [12,13]. cfu/g [16]. Scanning of available literature reveals that Colonies showing hemolytic zone are considered as percentage of E. coli isolation and identification varies heamolytic positive. While isolates, producing intense considerably [17,18]. The variation in percentage of E. orange or brick red colour on Congo red medium were coli isolation and identification may be due to considered as positive and those producing grayish difference in hygienic conditions at different slaughter white colonies recorded as negative. houses. All the 22 E. coli isolates shown typical Grams Antibiogram of E. coli: Antibiotic sensitivity of all staining reaction, biochemical reactions, motility and pathogenic E. coli isolates was done by disc diffusion sugar fermentation reactions described earlier [11]. method [14] on Muller-Hinkton agar. Three antimicro- Many workers successfully used staining characters, bial discs were used with different concentrations viz, Gentamycin (10 mcg), Tetracycline (30mcg) and biochemical reactions, sugar fermentation reactions Enrofloxacin (10mcg). Zones of complete inhibition and motility patterns for confirmation of E. coli were measured in millimeter with rule. isolated from meat [19]. Hemolysis of sheep RBC is an important criterion Results for identification of pathogenic strains of E. coli. In- 250 buffalo meat samples were screened for vitro pathogenecity studies of hemolytic E. coli were isolation of E. coli on EMB agar. A total of 22 E. coli done by using 5 percent sheep blood agar [20]. Many isolates were obtained. The isolates were identified workers successfully used Congo red binding assay in based upon colony characteristics comprising of bluish tryptose soya agar for identification of pathogenic E. green metallic sheen. The percentage of E. coli coli [20-22]. The observations are in agreement with isolation observed was 8.80 percent . Having average earlier workers [20,21]. differential count of 22 isolates of E. coli on EMB agar Antimicrobial sensitivity testing of the patho- observed was 1.231 ± 0.136 logcfu/ gm. A total of 22 genic E. coli isolated from beef samples confirms that 10 E. coli isolates were subjected to identification based all 9 pathogenic isolates were highly sensitive to upon Grams staining, biochemical characters, sugar Gentamycin. Out of nine isolates 7 isolates shown fermentation and motility tests. All the 22 isolates were resistance to Enrofloxacin and Tetracycline. Similar subjected to in-vitro pathogenecity test that is reports in previous studies showed resistance of meat hemolysin test and Congo red binding assay. A total of borne E. coli to Gentamycin and Enrofloxacin [23], 9 E. coli isolates were found positive for pathogenecity Tetracycline and Ciprofloxacin [24,25]. In present in both the in-vitro pathogenecity tests. The percent study sensitivity of E. coli to Tetracyclin was observed 278 doi:10.5455/vetworld.2013.277-279 AntibioticsSIRAverage zone of Inhibition in mm Gentamycin 90020.00 ± 1.49 Enrofloxacin 20718.22 ± 3.58 Tetracycline 11711.44 ± 2.04 Table-1. Results of sensitivity pattern of E. coli isolates S - Sensitive, I - Intermediate sensitive, R - Resistant 0 1 2 3 4 5 6 7 8 9 Gentamycin Enrofloxacin Tetracycline Sensitive (S) Intermediate Sensitive (I) Resistant (R) Figure-1. Sensitivity pattern of E.coli isolates