The increasing public health problem of antimicrobial resistance (AMR) has been linked to the extensive antimicrobial use (AMU) in food animals. We conducted a survey among ruminant farmers in Selangor, Malaysia to assess their level of awareness on AMR, attitudes towards AMU, and determinants that influence their practices. The survey was developed in English and Malay, validated, and administered to ruminant farmers in Selangor. A total of 84 farmers (response rate of 55%) completed the structured questionnaire. They appeared to be little aware of AMR and the impact on animals and public health. Indications of inappropriate AMU include their misconception on conditions requiring antibiotic therapy and easy accessibility to antibiotics. More than 70% (60/84) of the respondents believed that all sick animals need to be given antimicrobials. Half of the farmers especially those involved in the production of small and large ruminants; namely mixed ruminant farmers (MRF) (63%, 31/49) indicated that antimicrobials do not have any side effects in animals. Sixty-four percent (54/84) of the farmers have stored antimicrobials in their farms of which the practice was more common (P = 0.02) among the MRF compared to the single ruminant farmers (SRF). Although most of the farmers felt good farm biosecurity will help reduce AMU, they were indifferent regarding using antimicrobials only when prescribed by a veterinarian and non-storage of antimicrobials for later uses. Farmers with larger herd size (>100 animals/herd) and few years of farming experience agreed more to the suggestions about their role and that of veterinarians respectively in reducing the drivers of AMR. These areas might need to be considered by advisors to inform ruminant farmers on AMR and to encourage them for prudent AMU in food-producing animals.

Specific Escherichia coli isolates lysogenised with prophages that express Shiga toxin (Stx) can be a threat to human health, with cattle being an important natural reservoir. In many countries the most severe pathology is associated with enterohaemorrhagic E. coli (EHEC) serogroups that express Stx subtype 2a. In the United Kingdom, phage type (PT) 21/28 O157 strains have emerged as the predominant cause of life-threatening EHEC infections and this phage type commonly encodes both Stx2a and Stx2c toxin types. PT21/28 is also epidemiologically linked to super-shedding (>103 cfu/g of faeces) which is significant for inter-animal transmission and human infection as demonstrated using modelling studies. We demonstrate that Stx2a is the main toxin produced by stx2a+/stx2c+ PT21/28 strains induced with mitomycin C and this is associated with more rapid induction of gene expression from the Stx2a-encoding prophage compared to that from the Stx2c-encoding prophage. Bacterial supernatants containing either Stx2a and/or Stx2c were demonstrated to restrict growth of bovine gastrointestinal organoids with no restriction when toxin production was not induced or prevented by mutation. Isogenic strains that differed in their capacity to produce Stx2a were selected for experimental oral colonisation of calves to assess the significance of Stx2a for both super-shedding and transmission between animals. Restoration of Stx2a expression in a PT21/28 background significantly increased animal-to-animal transmission and the number of sentinel animals that became super-shedders. We propose that while both Stx2a and Stx2c can restrict regeneration of the epithelium, it is the relatively rapid and higher levels of Stx2a induction, compared to Stx2c, that have contributed to the successful emergence of Stx2a+ E. coli isolates in cattle in the last 40 years. We propose a model in which Stx2a enhances E. coli O157 colonisation of in-contact animals by restricting regeneration and turnover of the colonised gastrointestinal epithelium.

Overuse of antimicrobials in livestock health and production beyond therapeutic needs has been highlighted in recent years as one of the major risk factors for the acceleration of antimicrobial resistance (AMR) of bacteria in both humans and animals. While there is an abundance of reports on AMR in clinical isolates from humans, information regarding the patterns of resistance in clinical isolates from animals is scarce. Hence, a situational analysis of AMR based on clinical isolates from a veterinary diagnostic laboratory was performed to examine the extent and patterns of resistance demonstrated by isolates from diseased food animals. Between 2015 and 2017, 241 cases of diseased livestock were received. Clinical specimens from ruminants (cattle, goats and sheep), and non-ruminants (pigs and chicken) were received for culture and sensitivity testing. A total of 701 isolates were recovered from these specimens. From ruminants, Escherichia coli (n = 77, 19.3%) predominated, followed by Staphylococcus aureus (n = 73, 18.3%). Antibiotic sensitivity testing (AST) revealed that E. coli resistance was highest for penicillin, streptomycin, and neomycin (77–93%). In addition, S. aureus was highly resistant to neomycin, followed by streptomycin and ampicillin (68–82%). More than 67% of E. coli isolates were multi-drug resistant (MDR) and only 2.6% were susceptible to all the tested antibiotics. Similarly, 65.6% of S. aureus isolates were MDR and only 5.5% were susceptible to all tested antibiotics. From non-ruminants, a total of 301 isolates were recovered. Escherichia coli (n = 108, 35.9%) and Staphylococcus spp. (n = 27, 9%) were the most frequent isolates obtained. For E. coli, the highest resistance was against amoxicillin, erythromycin, tetracycline, and neomycin (95–100%). Staphylococcus spp. had a high level of resistance to streptomycin, trimethoprim/sulfamethoxazole, tetracycline and gentamicin (80–100%). The MDR levels of E. coli and Staphylococcus spp. isolates from non-ruminants were 72.2 and 74.1%, respectively. Significantly higher resistance level were observed among isolates from non-ruminants compared to ruminants for tetracycline, amoxicillin, enrofloxacin, and trimethoprim/sulfamethoxazole.

؉ and ␥␦ T cells from both PT21/28-and PT32-challenged calves following ex vivo restimulation with T3SPs. This study demonstrates that cattle mount cellular immune responses during colonization with EHEC O157: H7, the temporality of which is strain dependent, with further evidence of strain-specific immunomodulation.