Materials and Methods: Tissue samples were collected from 24 broiler breeder chickens from four commercial broiler breeder farms and six layer chickens from one layer farm. Gross and histopathological examinations and PCR amplification of the gene encoding for avian MD herpesvirus (MDV-1) were conducted.
Results: Gross pathological changes including hepatomegaly, splenomegaly, lymphomatous lesion at the mesentery, oviduct atrophy, and follicular atresia with lymphomatous were observed, whereas diffuse multifocal whitish infiltration of the spleen, neoplastic infiltration in the liver, intrafollicular lymphoid infiltration of the bursa of Fabricius, and lymphomatous tumor at the mesentery were seen on histopathological examinations. Confirmation by PCR showed that a total of 16 (53.33%) samples were positive for avian MDV-1. Although the outbreak involved a much larger number of birds in the respective farms, our investigation was limited based on resource and time frame allocated for the study.
Conclusion: The findings from this study help in emphasizing the potential threats of MDV to the poultry industry globally, in general, and in Malaysia, in particular. As the scope of the current study is limited, future studies focusing on MDV pathogenesis, typing, and causes of vaccine failures are recommended.
OBJECTIVES: Here, the efficacy of graphene oxide (GO), a carbon-based nanomaterial, was tested against the biofilms and intracellular S. aureus invitro. Following that, the mechanism for the intracellular antimicrobial activities and GO toxicities was elucidated.
METHODS: GO antibiofilm properties were evaluated based on the disruption of biofilm structure, and the intracellular antimicrobial activities were determined by the survival of S. aureus in infected bovine mammary cells following GO exposure. The mechanism for GO intracellular antimicrobial activities was investigated using endocytosis inhibitors. GO toxicity towards the host cells was assessed using a resazurin assay.
RESULTS: At 100 ug/mL, GO reduced between 30 and 70% of S. aureus biofilm mass, suggesting GO's ability to disrupt the biofilm structure. At 200 ug/mL, GO killed almost 80% of intracellular S. aureus, and the antimicrobial activities were inhibited when cells were pre-treated with cytochalasin D, suggesting GO intracellular antimicrobial activities were dependent on the actin-polymerization of the cell membrane. At
RESULTS: Four hundred fifty-three cloacal and farm environment samples were collected from six different commercial chicken farms in Kelantan, Malaysia. E. coli was isolated using standard bacteriological methods, and the isolates were tested for antimicrobial susceptibility using disc diffusion and colistin minimum inhibitory concentration (MIC) by broth microdilution. Multiplex PCR was used to detect mcr genes, and DNA sequencing was used to confirm the resistance genes. Virulence gene detection, phylogroup, and multilocus sequence typing (MLST) were done to further characterize the E. coli isolates. Out of the 425 (94%; 425/453) E. coli isolated from the chicken and farm environment samples, 10.8% (48/425) isolates were carrying one or more colistin-resistance encoding genes. Of the 48 colistin-resistant isolates, 54.2% (26/48) of the mcr positive isolates were genotypically and phenotypically resistant to colistin with MIC of colistin ≥ 4 μg/ml. The most prominent mcr gene detected was mcr-1 (47.9%; 23/48), followed by mcr-8 (18.8%; 9/48), mcr-7 (14.5%; 7/48), mcr-6 (12.5%; 6/48), mcr-4 (2.1%; 1/48), mcr-5 (2.1%; 1/48), and mcr-9 (2.1%; 1/48) genes. One E. coli isolate originating from the fecal sample was found to harbor both mcr-4 and mcr-6 genes and another isolate from the drinking water sample was carrying mcr-1 and mcr-8 genes. The majority of the mcr positive isolates were categorized under phylogroup A followed by phylogroup B1. The most prevalent sequence typing (ST) was ST1771 (n = 4) followed by ST206 (n = 3). 100% of the mcr positive E. coli isolates were multidrug resistant. The most frequently detected virulence genes among mcr positive E. coli isolates were ast (38%; 18/48) followed by iss (23%; 11/48). This is the first research to report the prevalence of mcr-4, mcr-5, mcr-6, mcr-7, and mcr-8 genes in E. coli from broiler chickens and farm environments in Malaysia.
CONCLUSION: Our findings suggest that broiler chickens and broiler farm environments could be reservoirs of colistin-resistant E. coli, posing a risk to public health and food safety.