Cattle are considered as one of the sources of pathogenic E. coli worldwide. The present study was designed to determine the prevalence and identification of the E. coli isolated from rectal swab of apparently healthy cattle in Mymensingh, Bangladesh. A total of 128 rectal swab samples were assessed by cultural, morphological and biochemical examination followed by Polymerase Chain Reaction (PCR) using primers ECO-1 and ECO-2 that are specific for E. coli 16S rRNA gene. Data obtained from this study were analyzed based on the age, sex, breed and management systems of cattle. This study revealed a 75% prevalence of E. coli in the rectal swab of cattle. Higher prevalence was found in female cattle of unorganized farming systems, and in cattle ≥3 years of age. From this study, it may be concluded that, irrespective of age, sex, breed and management system, E. coli is prevailing in the rectal swab of apparently healthy cattle.

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Objective: Cattle are regarded as the principle reservoir of O157 and non-O157 shigatoxigenic Escherichia coli (STEC). Spreading of the STEC to human is primarily happens through contaminated meat, milk and their byproducts. The present study was aimed to explore the occurrence of STEC in the rectal swab of apparently healthy cattle. Materials and methods: A total of 60 E. coli isolates that were previously isolated from the rectal swab of cattle were used in this study. DNA were extracted from the isolates and screened by PCR to detect E. coli stx (stx1, stx2), ehxA and rfbO157 genes. Representative amplicons of the PCR products were sequenced. The prevalence of the STEC was determined based on the detection of STEC specific stx genes. The prevalence data were further analyzed by SPSS to elucidate any difference among different demographic groups of the study population. Results: Overall, 43.33% (n=26/60) of the isolates were found carrying stx genes. Based on the presence of stx and ehxA genes, 6 different types of STEC were identified, of which 20% (n=12/26) were carrying both stx1 and stx2 genes. None of the isolates was positive for rfbO157. The PCR amplicons were sequenced, and the nucleotide sequences were deposited in GenBank (accession: KM596779-KM596784). Conclusion: In this study, non-O157 STEC were found highly prevalent in the local cattle. This study suggests that the apparently healthy cattle may act as a potential source of STEC infection for humans.

Objective: The present study was carried out to identify the associated Salmonella and Escherichia coli in betel leaves (Piper betle), and to develop an effective method to remove those microbes. Materials and methods: Betel leaves were collected from local and whole sale markets, and borouj (cultivation place). Salmonella and E. coli were isolated and identified by cultural, morphological, and biochemical tests followed by confirmation by polymerase chain reaction (PCR) targeting the genus specific 16S rRNA genes. Antibiogram of the isolated bacteria was performed by disc diffusion method. Different concentrations of Salmosan-A Soln were used to remediate the contaminating bacteria keeping the quality of betel leaves for longer periods. Results: Total Salmonella counts in the betel leaves were 3.9×10 5 , 4.9×10 6 , 3.5×10 4 , 1.1×10 3 and 1.5×10 3 CFU/mL, while E. coli counts were 5.5×10 7 , 6.3×10 7 , 4.4×10 5 , 3.3×10 3 and 3.1×10 3 CFU/mL in the betel leaves collected from K.R. market, Kewatkhali Bazaar, whole sale market, borouj in Kushtia and borouj in Natore, respectively. Antibiogram study revealed that the isolated bacteria were sensitive to doxycyclline, ciprofloxacin, chloramphenicol and cefotaxime. Application of 0.3% Salmosan-A Soln was found to be the most effective and suitable, where <1 CFU/mL in the betel leaves could be detected after treatment for 10 min. Conclusion: Results of this study indicated that treatment with 0.3% Salmosan-A Soln for 10 min is capable of removing Salmonella and E. coli from betel leaves keeping the treated leaves fresh up to 7 days of post-treatment. Method developed in this study can be adapted to reduce bacterial contamination of betel leaves more effectively in Bangladesh and other betel leaf exporting countries. KEYWORDS