Leptospirosis is an important zoonotic disease that is often associated with animal carriers and contamination of the environment via infected urine. This study aimed to assess pathogenic leptospiral carriage in Nan province, a rural area of Thailand where leptospirosis is endemic. Samples from 20 villages were obtained during the period 2013 to 2016, comprising urine samples collected from asymptomatic people (n=37) and domestic animals (n=342), and environmental water samples (n=14). Leptospira were cultured in Ellinghauson McCullough Johnson and Harris (EMJH) media. An rrs nested PCR identified 9.92% (95% confidence interval (CI) 6.96-12.88) of the urine and water samples as being positive for Leptospira spp., and phylogenetic analysis was conducted on the 443bp amplicons. Leptospira weilii, which has not previously been identified in Thailand, was recovered from 13 cattle, 9 pigs, 2 dogs, 2 water samples and 1 goat. L. interrogans was found in 4 dogs, 3 pigs, 3 cattle, 1 human and 1 water sample. Four leptospiral strains were isolated and multilocus sequence typing (MLST) analysis was performed on these. Three novel sequence types were identified, including two singletons of L. interrogans in ST26 and ST33, and one of L. weilii in ST94, with this having a close relationship to previous isolates from cases of human leptospirosis in Laos and China. Our results revealed that pathogenic Leptospira occur commonly in asymptomatic domestic animals, humans and environmental water samples in Nan Province, and emphasize the high potential for zoonotic transmission in the province.

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This study examined antimicrobial resistance (AMR) profiles in commensal Escherichia coli derived from healthy fattening pigs in Thai farms that used prophylactic antimicrobials (in-feed tiamulin fumarate and amoxicillin) [PAs], therapeutic antimicrobials (injectable enrofloxacin or gentamicin) [TAs], or no antimicrobials [NAs]. Commensal E. coli were used as a proxy for overall AMR on the farms. There was a high level of multidrug resistance in all three categories of farm, with isolates showing resistance to β-lactams (amoxicillin, ampicillin, and piperacillin) and tetracyclines (tetracycline), and commonly possessing tetA, bla, and plasmid replicons FIB and F. On the other hand, isolates with an extended-spectrum beta-lactamase phenotype (ESBLP) and with resistance to aminoglycosides, chloramphenicol, fluoroquinolones, nitrofurantoin, tiamulin, and trimethoprim/sulfamethoxazole were significantly more common among the PA farms (p < 0.05) than in the other two farm categories. In the PA farms, ESBLP E. coli commonly contained the bla group, bla group, or both gene groups, and were shown to transfer bla genes in a conjugation experiment. E. coli containing N, FIC and A/C replicons were found only in PA farms. In summary, although E. coli isolates from all farms contained a core set of resistance to β-lactams and tetracyclines, the routine use of PA increased resistance rates to other important antimicrobials.

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The aims of this study were (i) to evaluate whether routine in-feed antimicrobial use in pigs or not resulted in differences in antimicrobial resistance (AMR) E. coli at different pig producing stages, and (ii) to determine whether resistant strains were presented in pig meat postslaughter. A total of 300 commensal E. coli isolates were obtained and examined for antibiograms, AMR genes, plasmid replicons, and molecular types. The isolates were from two farms either using (A) or not using in-feed antimicrobials (NA), sampled four times during the production cycle and once postslaughter. E. coli resistant to aminoglycosides containing aadA1, aadA2, and aadB and extended-spectrum beta-lactamase-producing (ESBLP) E. coli containing blaCTX-M-1 were significantly increased in the nursery and growing periods in farm A compared to farm NA. IncI1-Iγ and IncHI2 were common in the nursery period and were shown to transfer blaCTX-M genes by conjugation. ST10 was the most common type only found in live pigs. ST604, ST877, ST1209, and ST2798 ESBLP were found only in live pigs, whereas ST72, ST302, and ST402 ESBLP were found in pig meat.

Highlights: 3 addition, we show that ST1 clones carry a constellation of putative virulence genes not present in other Australian STs.

Antimicrobial resistance (AMR) is a critical challenge worldwide as it impacts public health, especially via contamination in the food chain and in healthcare-associated infections. In relation to farming, the systems used, waste management on farms, and the production line process are all determinants reflecting the risk of AMR emergence and rate of contamination of foodstuffs. This review focuses on South East Asia (SEA), which contains diverse regions covering 11 countries, each having different levels of development, customs, laws, and regulations. Routinely, here as elsewhere antimicrobials are still used for three indications: therapy, prevention, and growth promotion, and these are the fundamental drivers of AMR development and persistence. The accuracy of detection of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) depends on the laboratory standards applicable in the various institutes and countries, and this affects the consistency of regional data. Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae are the standard proxy species used for indicating AMR-associated nosocomial infections and healthcare-associated infections. Pig feces and wastewater have been suspected as one of the hotspots for spread and circulation of ARB and ARG. As part of AMR surveillance in a One Health approach, clonal typing is used to identify bacterial clonal transmission from the production process to consumers and patients – although to date there have been few published definitive studies about this in SEA. Various alternatives to antibiotics are available to reduce antibiotic use on farms. Certain of these alternatives together with improved disease prevention methods are essential tools to reduce antimicrobial usage in swine farms and to support global policy. This review highlights evidence for potential transfer of resistant bacteria from food animals to humans, and awareness and understanding of AMR through a description of the occurrence of AMR in pig farm food chains under SEA management systems. The latter includes a description of standard pig farming practices, detection of AMR and clonal analysis of bacteria, and AMR in the food chain and associated environments. Finally, the possibility of using alternatives to antibiotics and improving policies for future strategies in combating AMR in a SEA context are outlined.