Most humans are in contact with animals in a way or another. A zoonotic disease is a disease or infection that can be transmitted naturally from vertebrate animals to humans or from humans to vertebrate animals. More than 60% of human pathogens are zoonotic in origin. This includes a wide variety of bacteria, viruses, fungi, protozoa, parasites, and other pathogens. Factors such as climate change, urbanization, animal migration and trade, travel and tourism, vector biology, anthropogenic factors, and natural factors have greatly influenced the emergence, re-emergence, distribution, and patterns of zoonoses. As time goes on, there are more emerging and re-emerging zoonotic diseases. In this review, we reviewed the etiology of major zoonotic diseases, their impact on human health, and control measures for better management. We also highlighted COVID-19, a newly emerging zoonotic disease of likely bat origin that has affected millions of humans along with devastating global consequences. The implementation of One Health measures is highly recommended for the effective prevention and control of possible zoonosis.

Avian pathogenic Escherichia coli (APEC) causes significant economic losses in poultry industries. Here, we determined for the first time in Bangladesh, the prevalence of APEC-associated virulence genes in E. coli isolated from layer farms and their antibiotic resistance patterns. A total of 99 samples comprising internal organs, feces, and air were collected from 32 layer farms. Isolation was performed by culturing samples on eosin–methylene blue agar plates, while the molecular detection of APEC was performed by PCR, and antibiograms were performed by disk diffusion. Among the samples, 36 were positive for the APEC-associated virulence genes fimC, iucD, and papC. Out of 36 isolates, 7, 18, and 11 were positive, respectively, for three virulence genes (papC, fimC, and iucD), two virulence genes, and a single virulence gene. Although the detection of virulence genes was significantly higher in the internal organs, the air and feces were also positive. The antibiograms revealed that all the isolates (100%) were resistant to ampicillin and tetracycline; 97.2%, to chloramphenicol and erythromycin; 55.5%, to enrofloxacin; 50.0%, to norfloxacin and ciprofloxacin; 19.4%, to streptomycin; 11.1%, to colistin; and 8.33%, to gentamicin. Interestingly, all the isolates were multidrug-resistant (MDR). Spearman’s rank correlation coefficient analysis revealed the strongest significant correlation between norfloxacin and ciprofloxacin resistance. This is the first study in Bangladesh describing the molecular detection of APEC in layer farms. Isolated APEC can now be used for detailed genetic characterization and assessing the impact on public health.

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.

Staphylococcus aureus is a major foodborne pathogen. The ability of S. aureus to produce biofilm is a significant virulence factor, triggering its persistence in hostile environments. In this study, we screened a total of 420 different food samples and human hand swabs to detect S. aureus and to determine their biofilm formation ability. Samples analyzed were meat, milk, eggs, fish, fast foods, and hand swabs. S. aureus were detected by culturing, staining, biochemical, and PCR. Biofilm formation ability was determined by Congo Red Agar (CRA) plate and Crystal Violet Microtiter Plate (CVMP) tests. The icaA, icaB, icaC, icaD, and bap genes involved in the synthesis of biofilm-forming intracellular adhesion compounds were detected by PCR. About 23.81% (100/420; 95% CI: 14.17–29.98%) of the samples harbored S. aureus, as revealed by detection of the nuc gene. The CRA plate test revealed 20% of S. aureus isolates as strong biofilm producers and 69% and 11% as intermediate and non-biofilm producers, respectively. By the CVMP staining method, 20%, 77%, and 3% of the isolates were found to be strong, intermediate, and non-biofilm producers. Furthermore, 21% of S. aureus isolates carried at least one biofilm-forming gene, where icaA, icaB, icaC, icaD, and bap genes were detected in 15%, 20%, 7%, 20%, and 10% of the S. aureus isolates, respectively. Bivariate analysis showed highly significant correlations (p < 0.001) between any of the two adhesion genes of S. aureus isolates. To the best of our knowledge, this is the first study in Bangladesh describing the detection of biofilm-forming S. aureus from foods and hand swabs using molecular-based evidence. Our findings suggest that food samples should be deemed a potential reservoir of biofilm-forming S. aureus, which indicates a potential public health significance.

Antimicrobial resistance (AMR) in Salmonella in poultry poses a serious human health threat as it has zoonotic importance. Poultry is often linked with outbreaks of Salmonella-associated foodborne illness. Since antimicrobials are heavily used in poultry in Bangladesh, multidrug-resistant (MDR) Salmonella is quite frequently found there. MDR Salmonella is challenging to treat with antimicrobials and often causes a severe economic loss in the poultry sector. By horizontal gene transfer and/or evolutionary mutations, antimicrobials primarily exert selection pressure that contributes to antimicrobials resistance. In addition, resistance patterns can vary with variations in time and space. Without having prior knowledge of resistance patterns, no effective drugs could be prescribed. Therefore, it is crucial to have updated knowledge on the status of AMR in Salmonella in Bangladesh for effective treatment and management of the flocks against salmonellosis. There are several review articles on AMR in Salmonella in poultry in Bangladesh; they lack the whole scenario of the country and particularly do not have enough data on the poultry environment. Considering this scenario, in this review, we have focused on AMR in Salmonella in poultry in Bangladesh (2011–2021), with particular emphasis on data from the poultry and farm environments on a divisional zone basis.

The eradication of staphylococcal infections has become more difficult due to the development of antibiotic resistance and virulence in biofilm-forming Staphylococcus aureus. The presence of the life-threatening zoonotic pathogen, methicillin-resistant S. aureus (MRSA), in foods indicates a public health issue. This study, therefore, aimed to determine virulence factors and methicillin resistance in biofilm-forming S. aureus isolates from different foods and food handlers. A total of 100 PCR-positive S. aureus isolates (97 biofilm formers and three non-biofilm formers) were screened using the disk diffusion method and PCR assay. By PCR, genes encoding virulence factors, e.g., enterotoxin (sea, 30%, 95% CI: 21.90–39.59%), toxic shock syndrome toxin (tst, 20%, 95% CI: 13.34–28.88%), and Panton–Valentine leukocidin toxin (PVL, 15%, 95% CI: 9.31–23.28%), were detected in the S. aureus isolates. By the disk diffusion method, 100% (95% CI: 96.30–100.00%) of S. aureus isolates were phenotypically MRSA in nature, showing 100% resistance to oxacillin and cefoxitin. Moreover, the methicillin-resistant gene mecA was found in 61 (61%, 95% CI: 51.20–69.98%) MRSA isolates. Furthermore, all the S. aureus isolates were phenotypically resistant to ampicillin and penicillin, 30% to erythromycin, and 11% to gentamycin. Among them, 51% (95% CI: 41.35–60.58%) of S. aureus isolates were phenotypically multidrug-resistant in nature, and the multiple antibiotic resistance index varied from 0.33 to 0.55. Genes encoding resistance to beta-lactams (blaZ, 100%, 95% CI: 96.30–100.00%) and tetracyclines (tetA and tetC, 3%, 95% CI: 0.82–8.45%) were found positive in the S. aureus isolates. Genes encoding virulence determinants and MRSA were significantly (p < 0.05) higher in strong biofilm-forming S. aureus than in moderate and non-biofilm-forming isolates. To our knowledge, this is the first study in Bangladesh to incorporate preliminary data on the occurrence of virulence determinants and methicillin resistance, including resistance to clinically important antibiotics, in biofilm-forming S. aureus isolates from different foods and food handlers in Bangladesh, emphasizing a potential threat to human health.