Migratory birds are carriers of multidrug resistant pathogenic Escherichia coli. However, their roles in the dissemination of these resistant pathogens are still being neglected in Bangladesh. The present study was therefore carried out to detect multidrug resistant E. coli. In addition, these isolates were also screened for the presence of avian pathogenic E. coli (APEC)-associated virulence genes. A total of 66 fecal matter samples of migratory birds were screened. E. coli were isolated and identified by culturing and biochemical tests followed by polymerase chain reaction (PCR). APEC-associated virulence genes were detected by PCR. Disk diffusion assays were employed to investigate antibiogram profiles. Bivariate analysis was performed to assess correlations in resistance patterns between antimicrobials and to assess associations between virulence genes of E. coli. Among the 66 samples assessed by PCR, 55 (83.33%) were found positive for E. coli. Of these 55 isolates, the APEC-associated virulence gene fimC was detected in 67.27% of the isolates, which was significantly higher than in the cases of iucD (29.09%) and papC (5.45%) genes. In addition, three isolates were found positive for all three virulence genes, while 23 and 12 isolates were positive for one and two virulence genes respectively. In the bivariate analysis, significant associations were detected between fimC and iucD virulence genes. Using the antibiogram, all E. coli isolates were found to be multidrug resistant (MDR). The isolates exhibited 100% resistance against ampicillin and erythromycin in addition to varying percentages of resistance against streptomycin, tetracycline, ciprofloxacin, and chloramphenicol. Highly positive correlations between tetracycline and ciprofloxacin, chloramphenicol and ciprofloxacin, chloramphenicol and tetracycline were observed by bivariate analysis. To the best of our knowledge, this is the first study that reports APEC-associated virulence genes of MDR E. coli from migratory birds in Bangladesh. Results indicate that migratory birds are reservoirs of MDR E. coli isolates carrying APEC-associated virulence genes, which can seriously contribute to the development of human and animal diseases.

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli cause severe health hazards. Migratory birds are reservoirs and transmitters of many pathogens including ESBL-producing E. coli . To examine migratory birds as potential carriers of ESBL-producing E. coli and E. coli -carrying antibiotic resistance genes, 55 PCR-positive E. coli isolates were screened using the disk diffusion method, double-disk synergy test, and further polymerase chain reaction (PCR) tests. Genes encoding resistance to tetracycline [ tetA , 100% (35/35); tetB , 31.43% (11/35)], fluoroquinolone [ qnrA , 35.71% (10/28); qnrB , 25% (7/28)], and streptomycin [ aadA1 , 90.24% (37/41)] were detected in the isolated E. coli . Of the 55 E. coli isolates, 21 (38.18%) were ESBL producers, and all of them were multidrug resistant. All the ESBL-producing E. coli isolates harbored at least two or more beta-lactamase genes, of which bla TEM , bla CMY , bla CTX-M , and bla SHV were detected in 95.24%, 90.48%, 85.71%, and 42.86% of isolates, respectively. All the beta-lactamase genes were present in four of the ESBL-producing E. coli isolates. Furthermore, 95.24% of ESBL-producing E. coli isolates were positive for one or more antibiotic resistance genes. To the best of our knowledge, this is the first study to detect E. coli -carrying antibiotic resistance genes including beta-lactamase bla CMY and bla SHV originating from migratory birds in Bangladesh. These results suggest that migratory birds are potential carriers of ESBL-producing E. coli along with other clinically important antibiotic resistance genes which may have detrimental impacts on human health.

Antimicrobial resistance (AMR) is a major health crisis globally. Migratory birds could be a potential source for antibiotic resistant (ABR) bacteria. Not much is known about their role in the transmission of ABR in Bangladesh. In this study, a total of 66 freshly dropped fecal materials of migratory birds were analyzed. Bacterial isolation and identification were based on cultural properties, biochemical tests, and polymerase chain reaction (PCR). The disk diffusion method was employed to evaluate antibiogram profiles. By PCR, out of 66 samples, the detection rate of Enterococcus spp. (60.61%; 95% confidence interval: 48.55–71.50%) was found significantly higher than Salmonella spp. (21.21%; 95% CI: 13.08–32.51%) and Vibrio spp. (39.40%; 95% CI: 28.50–51.45%). Enterococcus isolates were frequently found resistant (100–40%) to ampicillin, streptomycin, meropenem, erythromycin, and gentamicin; Salmonella isolates were frequently resistant (72–43%) to chloramphenicol, tetracycline, ampicillin, streptomycin, and erythromycin; and Vibrio spp. isolates were frequently resistant (77–31%) to vancomycin, ampicillin, erythromycin, tetracycline, and streptomycin. In addition, 60% (95% CI: 44.60–73.65%) Enterococcus spp., 85.71% (95% CI: 60.06–97.46%) Salmonella spp., and 76.92% (95% CI: 57.95–88.97%) Vibrio spp. isolates were multi-drug resistant (MDR) in nature. Three isolates (one from each bacterium) were found resistant against six classes of antibiotics. The bivariate analysis revealed strong associations (both positive and negative) between several antibiotic pairs which were resistant to isolated organisms. To the best of our knowledge, this is the first study in detecting MDR Enterococcus spp., Salmonella spp., and Vibrio spp. from migratory birds travelling to Bangladesh. Frequent detection of MDR bacteria from migratory birds travelling to Bangladesh suggests that these birds have the potential to carry and spread ABR bacteria and could implicate potential risks to public health. We recommend that these birds should be kept under an AMR surveillance program to minimize the potential risk of contamination of the environment with ABR as well as to reduce their hazardous impacts on health.

The present research work was undertaken to find out the passive causes of occurrences of diarrhoea in terms of age, sex, season and location differences through isolation and identification of the E. coli and Salmonella spp. using cultural, biochemical and molecular from the field samples of the diarrhoeic cattle and to study the antibiogram profiles of the isolated bacterial species. Considering above purposes, a total of 57 rectal swab samples were collected from the diarrhoeic cattle of Mymensingh sadar, Trishal, Valuka, Natore sadar and Gomostapur, Chapai Nawabganj. Different types of cultural media like Nutrient agar, MacConkey`s (MC) agar, Eosin Methylene Blue (EMB) agar, Salmonella-Shigella (SS) agar, Xylose-Lysine-Deoxycholate (XLD) agar and Blood agar were used to isolate and to study the cultural properties of the E. coli and Salmonella spp. Finally Gram's staining and different biochemical tests were performed to identify those two bacterial species. Out of 57 samples, 27 were positive for E. coli and 8 were positive for Salmonella spp. On the basis of information from cattle owners and clinical signs the prevalence of diarrhoea was recorded as 30.99% and the pvalue was calculated as 0.001 (p<0.01) which was noted as highly significant. The prevalence percentages of the E. coli and Salmonella spp. were differed depending on different epidemiological parameters like age, sex, season and location. Moreover, the molecular identifications were further confirmed by means of PCR assay using specific primers for E. coli and Salmonella spp. This was done targeting 16S rRNA gene where they were found to be positive showing amplification of 585 bp for E. coli and 574 bp for Salmonella spp. From the study of the antibiogram profiles, it was revealed that E. coli were susceptible to ciprofloxacin, gentamicin and norfloxacin but resistant to tetracycline, erythromycin, amoxicillin and streptomycin whereas Salmonella spp. were susceptible to ciprofloxacin, gentamicin, amoxicillin and streptomycin but resistant to azithromycin, tetracycline and erythromycin. The findings of this research work would certainly help to select the proper antibiotics against diarrhoea in cattle of Bangladesh and to overcome the multi-drug resistant problem of the bacteria.

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