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The incidence of antimicrobial resistance (AMR) in the environment is often overlooked and leads to serious health threats under the One Health paradigm. Infection with extended-spectrum β-lactamase (ESBL) producing bacteria in humans and animals has been widely examined, with the mode of transmission routes such as food, water, and contact with a contaminated environment. The purpose of this study was to determine the occurrence and molecular characteristics of resistant Salmonella enterica (S. enterica) (n = 59) and Escherichia coli (E. coli) (n = 392) isolated from produce commodities collected from fresh markets and supermarkets in Bangkok, Thailand. In this study, the S. enterica isolates exhibited the highest prevalence of resistance to tetracycline (11.9%) and streptomycin (8.5%), while the E. coli isolates were predominantly resistant to tetracycline (22.5%), ampicillin (21.4%), and sulfamethoxazole (11.5%). Among isolates of S. enterica (6.8%) and E. coli (15.3%) were determined as multidrug resistant (MDR). The prevalence of ESBL-producing isolates was 5.1% and 1.0% in S. enterica and E. coli, respectively. A minority of S. enterica isolates, where a single isolate exclusively carried blaCTX-M-55 (n = 1), and another isolate harbored both blaCTX-M-55 and blaTEM-1 (n = 1); similarly, a minority of E. coli isolates contained blaCTX-M-55 (n = 2) and blaCTX-M-15 (n = 1). QnrS (11.9%) and blaTEM (20.2%) were the most common resistant genes found in S. enterica and E. coli, respectively. Nine isolates resistant to ciprofloxacin contained point mutations in gyrA and parC. In addition, the odds of resistance to tetracycline among isolates of S. enterica were positively associated with the co-occurrence of ampicillin resistance and the presence of tetB (P = 0.001), while the E. coli isolates were positively associated with ampicillin resistance, streptomycin resistance, and the presence of tetA (P

The objective of this study was to evaluate the impact of dietary zinc supplementation in pre-weaned dairy calves on the phenotypic antimicrobial resistance (AMR) of fecal commensal bacteria. A repository of fecal specimens from a random sample of calves block-randomized into placebo (n = 39) and zinc sulfate (n = 28) groups collected over a zinc supplementation clinical trial at the onset of calf diarrhea, calf diarrheal cure, and the last day of 14 cumulative days of zinc or placebo treatment were analyzed. Antimicrobial susceptibility testing was conducted for Enterococcus spp. (n = 167) and E. coli (n = 44), with one representative isolate of each commensal bacteria tested per sample. Parametric survival interval regression models were constructed to evaluate the association between zinc treatment and phenotypic AMR, with exponentiated accelerated failure time (AFT) coefficients adapted for MIC instead of time representing the degree of change in AMR (MIC Ratio, MR). Findings from our study indicated that zinc supplementation did not significantly alter the MIC in Enterococcus spp. for 13 drugs: gentamicin, vancomycin, ciprofloxacin, erythromycin, penicillin, nitrofurantoin, linezolid, quinupristin/dalfopristin, tylosin tartrate, streptomycin, daptomycin, chloramphenicol, and tigecycline (MR = 0.96-2.94, p > 0.05). In E. coli, zinc supplementation was not associated with resistance to azithromycin (MR = 0.80, p > 0.05) and ceftriaxone (MR = 0.95, p > 0.05). However, a significant reduction in E. coli MIC values was observed for ciprofloxacin (MR = 0.17, 95% CI 0.03-0.97) and nalidixic acid (MR = 0.28, 95% CI 0.15-0.53) for zinc-treated compared to placebo-treated calves. Alongside predictions of MIC values generated from these 17 AFT models, findings from this study corroborate the influence of age and antimicrobial exposure on phenotypic AMR.

California Leafy Green Products Handler Marketing Agreement (LGMA) established food safety metrics with guidance recommendations of 366 m (1,200 feet) and 1,609 m (1 mile) distances between production fields of leafy greens and a concentrated animal feeding operation (CAFO) containing >1,000 and >80,000 head of cattle, respectively. This study evaluated the effect of these distance metrics and environmental factors on the occurrence of airborneEscherichia coliin proximity to seven commercial beef cattle feedlots located in Imperial Valley, California. A total of 168 air samples were collected from seven beef cattle feedlots during March and April 2020, which were the months implicated in the 2018 Yuma Arizona lettuce outbreak of E. coli O157:H7. The distance between air sampling sites and the edge of the feedlot ranged from ∼0 to ∼2,200 m (∼1.3 mile), with each sample comprised of 1,000 L of processed air taken at a 1.2 m elevation over a 10-minute duration. E. colicolonies were enumerated on CHROMagar ECC selective agar and confirmed with conventional PCR. Meteorological data (air temperature, wind speed, wind direction, relative humidity) were collectedin situ. The prevalence and mean concentration ofE. coliwere 6.55% (11/168) and 0.09 CFU per 1,000 L of air, with positive samples limited to within 37 m (120 ft) of the feedlot.Based on logistic regression, the odds of airborne E. coli detection were associated with little to no wind and close proximity to a feedlot. This pilot study found limited dispersal of airborne E. coli in proximity to commercial feedlots in Imperial Valley, with light-to-no wind and proximity within 37 m of a feedlot significant factor-associated airborne E. coli in this produce-growing region of California.

BackgroundTilapia is a primary aquaculture fish in Thailand, but little is known about the occurrence of antimicrobial resistance (AMR) in Aeromonas hydrophila, Salmonella spp., and Vibrio cholerae colonizing healthy tilapia intended for human consumption and the co-occurrence of these AMR bacteria in the cultivation water.MethodsThis study determined the phenotype and genotype of AMR, extended-spectrum β-lactamase (ESBL) production, and virulence factors of A. hydrophila, Salmonella spp., and V. cholerae isolated from hybrid red tilapia and cultivation water in Thailand. Standard culture methods such as USFDA's BAM or ISO procedures were used for the original isolation, with all isolates confirmed by biochemical tests, serotyping, and species-specific gene detection based on PCR.ResultsA total of 278 isolates consisting of 15 A. hydrophila, 188 Salmonella spp., and 75 V. cholerae isolates were retrieved from a previous study. All isolates of A. hydrophila and Salmonella isolates were resistance to at least one antimicrobial, with 26.7% and 72.3% of the isolates being multidrug resistant (MDR), respectively. All A. hydrophila isolates were resistant to ampicillin (100%), followed by oxytetracycline (26.7%), tetracycline (26.7%), trimethoprim (26.7%), and oxolinic acid (20.0%). The predominant resistance genes in A. hydrophila were mcr-3 (20.0%), followed by 13.3% of isolates having floR, qnrS, sul1, sul2, and dfrA1. Salmonella isolates also exhibited a high prevalence of resistance to ampicillin (79.3%), oxolinic acid (75.5%), oxytetracycline (71.8%), chloramphenicol (62.8%), and florfenicol (55.3%). The most common resistance genes in these Salmonella isolates were qnrS (65.4%), tetA (64.9%), bla TEM (63.8%), and floR (55.9%). All V. cholerae isolates were susceptible to all antimicrobials tested, while the most common resistance gene was sul1 (12.0%). One isolate of A. hydrophila was positive for int1, while all isolates of Salmonella and V. cholerae isolates were negative for integrons and int SXT. None of the bacterial isolates in this study were producing ESBL. The occurrence of mcr-3 (20.0%) in these isolates from tilapia aquaculture may signify a serious occupational and consumer health risk given that colistin is a last resort antimicrobial for treatment of Gram-negative bacteria infections.ConclusionsFindings from this study on AMR bacteria in hybrid red tilapia suggest that aquaculture as practiced in Thailand can select for ubiquitous AMR pathogens, mobile genetic elements, and an emerging reservoir of mcr and colistin-resistant bacteria. Resistant and pathogenic bacteria, such as resistance to ampicillin and tetracycline, or MDR Salmonella circulating in aquaculture, together highlight the public health concerns and foodborne risks of zoonotic pathogens in humans from cultured freshwater fish.

This study characterized the effect of distance from beef cattle feedlots, environmental factors, and climate on the occurrence of airborne bacterial indicators and pathogens. Three hundred air samples were collected over 6 months from five feedlots, with each air sample comprising 6000 L of air. Air samples were processed onto TSB-enriched air filters, qPCR-screened, and then qPCR-confirmed for suspect positive colonies of E. coli O157, non-O157-Shiga-toxin-producing E. coli (STEC), Salmonella, and E. coli. Direct enumeration of E. coli was also collected. Although no bacterial pathogens were qPCR-confirmed for the 300 samples, E. coli was detected in 16.7% (50/300) of samples, with an overall mean concentration of 0.17 CFU/6000 L air. Logistic regression analyses revealed a higher odds of E. coli for samples in close proximity compared to >610 m (2000 ft) distance from feedlots, along with significant associations with meteorological factors, sampling hour of day, and the presence of a dust-generating activity such as plowing a field or nearby vehicular traffic. The lack of bacterial pathogen detection suggests airborne deposition from nearby feedlots may not be a significant mechanism of leafy green bacterial pathogen contamination; the result of our study provides data to inform future revisions of produce-safety guidance.

BackgroundMicrobiota play important roles in the gastrointestinal tract (GIT) of dairy cattle as the communities are responsible for host health, growth, and production performance. However, a systematic characterization and comparison of microbial communities in the GIT of cattle housed in different management units on a modern dairy farm are still lacking. We used 16S rRNA gene sequencing to evaluate the fecal bacterial communities of 90 dairy cattle housed in 12 distinctly defined management units on a modern dairy farm.ResultsWe found that cattle from management units 5, 6, 8, and 9 had similar bacterial communities while the other units showed varying levels of differences. Hutch calves had a dramatically different bacterial community than adult cattle, with at least 10 genera exclusively detected in their samples but not in non-neonatal cattle. Moreover, we compared fecal bacteria of cattle from every pair of the management units and detailed the number and relative abundance of the significantly differential genera. Lastly, we identified 181 pairs of strongly correlated taxa in the community, showing possible synergistic or antagonistic relationships.ConclusionsThis study assesses the fecal microbiota of cattle from 12 distinctly defined management units along the production line on a California dairy farm. The results highlight the similarities and differences of fecal microbiota between cattle from each pair of the management units. Especially, the data indicate that the newborn calves host very different gut bacterial communities than non-neonatal cattle, while non-neonatal cattle adopt one of the two distinct types of gut bacterial communities with subtle differences among the management units. The gut microbial communities of dairy cattle change dramatically in bacterial abundances at different taxonomic levels along the production line. The findings provide a reference for research and practice in modern dairy farm management.

Coastal pollution is of public health concern due to the possibility of bacterial contamination in aquaculture affecting health risk and seafood safety. This study determined the concentrations of total coliforms, fecal coliforms, E. coli, and V. parahaemolyticus and the presence of V. cholerae and Salmonella in water and measured water quality and meteorological factors from the major oyster cultivation areas in Thailand. The water samples (n = 363) were collected from Surat Thani (n = 60), Chanthaburi (n = 60), Trat (n = 60), Phetchaburi (n = 60), Chonburi (n = 63), and Phang Nga (n = 60) from February 2021 to January 2022. The prevalence of total coliforms (96.7%), fecal coliforms (60.6%), E. coli (22.9%), along with the prevalence of Salmonella (2.5%), Vibrio parahaemolyticus (74.9%), and V. cholerae (11.3%) were determined. Common Salmonella serovars were Othmarschen and Lamberhurst. The concentration of E. coli was significantly associated with dissolved oxygen and precipitation (p < 0.0001). Therefore, continuing microbiological monitoring and surveillance of water for coastal aquaculture is important to produce safe aquatic products. Furthermore, raising awareness of coastal pollution and seafood safety will help enhance sustainable coastal fisheries in Thailand.

Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne illness worldwide. The objectives of this study were to determine the concentrations of indicator bacteria and the presence of Salmonella spp., Shigella spp., Escherichia coli (E. coli) O157:H7, and Listeria monocytogenes (L. monocytogenes), and to characterize predictors associated with Salmonella contamination of retail produce from fresh markets and supermarkets in Bangkok, Thailand. A total of 503 samples were collected during May 2018 and February 2019, comprised of sweet basil, spring onion, coriander, cabbage, lettuce, cucumber, and tomato, with conventional items from fresh open-air markets (n=167), conventional items from supermarkets (n=168), and organic items from supermarkets (n=168). The overall prevalence in these 503 items for fecal coliforms and E. coli was 84.3% and 71.4%, with mean concentrations (±standard deviation) of fecal coliforms and E. coli being (3.0×105±1.3×106) most probable number (MPN)/g and (1.8×105±1.1×105) MPN/g, respectively. The concentrations of fecal coliforms and E. coli were higher in produce sampled from fresh open-air markets than produce from supermarkets; similarly, these bacterial indicators were higher from produce grown under conventional methods than certified organic produce. The prevalence of Salmonella and Shigella was 4.8% and 0.4%, respectively, but no positives were found for E. coli O157:H7 and L. monocytogenes. The predominant Salmonella serovar was Stanley (30.8%). Based on logistic regression, the odds of Salmonella contamination were significantly (P

Microbial food safety in cultured tilapia remains a challenge to public health worldwide, due in part to intensive aquaculture leading to poor water quality and high organic matter deposition. This study aimed to determine the prevalence of indicator and potential pathogenic bacteria in hybrid red tilapia (Oreochromis spp.) and their cultivation water and to identify environmental parameters and other bacterial contaminants associated with Salmonella contamination. A total of 120 fish were sampled, which were partitioned into fish carcasses (n=120), muscle (n=120), intestine (n=120), liver and kidney (n=120), and cultivation water (n=120) from three commercial farms in western Thailand from October 2019 to November 2020. The prevalence of fecal coliforms and Escherichia coli (E. coli) in these 600 samples was 74.8% and 56.7%, respectively. The prevalence of Salmonella, Vibrio cholerae (V. cholerae), Aeromonas hydrophila, and Vibrio vulnificus (V. vulnificus) was 23.0%, 17.5%, 2.5%, and 1.7%, respectively. None of the samples tested positive for Streptococcus agalactiae. Cultivation water exhibited a high prevalence for Salmonella (58.3%). Among fish samples, Salmonella had the highest prevalence at 14.1%, which was mainly from fish intestine. There was a significant association of Salmonella with the presence of fecal coliforms, E. coli, V. cholerae, and V. vulnificus. The predominant serovars of Salmonella included Saintpaul, Neukoelln, Escanaba, and Papuana. Grazing ducks that were raised in proximity to these cultured tilapia shared the same isolates of Salmonella based on the similarity of their rep-PCR DNA fingerprints, suggesting that ducks may function as either a biological reservoir for tilapia or at minimum participate in the environmental replication of this strain of Salmonella. Taken together, the results suggest that the environment used for tilapia aquaculture may be contaminated with pathogenic bacteria; therefore, food safety precautions are needed during processing, transportation, cooking, and consumption.

Cryptosporidium spp. is a parasite that can infect a wide variety of vertebrate species. The parasite has been detected in sheep worldwide with diverse species and genotypes of various levels of zoonotic potential and public health concern. The purpose of this study was to determine the distribution of genotypes of Cryptosporidium in sheep in California, USA. Microscopic positive samples from individual sheep from central and northern California ranches were genotyped by sequencing a fragment of the 18S rRNA gene and BLAST analysis. Eighty-eight (63.8%) of the microscopic positive samples were genotyped, and multiple genotypes of Cryptosporidium were identified from sheep in the enrolled ranches. Approximately 89% of isolates (n = 78) were C. xiaoi or C. bovis, 10% of isolates (n = 9) were C. ubiquitum, and 1% of isolates (n = 1) were C. parvum. The C. parvum and C. ubiquitum isolates were detected only from lambs and limited to four farms. Given that the majority of Cryptosporidium species (i.e., C. xiaoi and C. bovis) were of minor zoonotic concern, the results of this study suggest that sheep are not a reservoir of major zoonotic Cryptosporidium in California ranches.

The occurrence of waterborne antimicrobial-resistant (AMR) bacteria in areas of high-density oyster cultivation is an ongoing environmental and public health threat given the popularity of shellfish consumption, water-related human recreation throughout coastal Thailand, and the geographical expansion of Thailand's shellfish industry. This study characterized the association of phenotypic and genotypic AMR, including extended-spectrum β-lactamase (ESBL) production, and virulence genes isolated from waterborne Escherichia coli (E. coli) (n = 84), Salmonella enterica (S. enterica) subsp. enterica (n = 12), Vibrio parahaemolyticus (V. parahaemolyticus) (n = 249), and Vibrio cholerae (V. cholerae) (n = 39) from Thailand's coastal aquaculture regions. All Salmonella (100.0%) and half of V. cholerae (51.3%) isolates harbored their unique virulence gene, invA and ompW, respectively. The majority of isolates of V. parahaemolyticus and E. coli, ~25% of S. enterica subsp. enterica, and ~12% of V. cholerae, exhibited phenotypic AMR to multiple antimicrobials, with 8.9% of all coastal water isolates exhibiting multidrug resistance (MDR). Taken together, we recommend that coastal water quality surveillance programs include monitoring for bacterial AMR for food safety and recreational water exposure to water for Thailand's coastal water resources.

Food-producing animals such as dairy cattle are potential reservoirs of antimicrobial resistance (AMR), with multidrug-resistant (MDR) organisms such as Escherichia coli observed in higher frequency in young calves compared to older cattle. In this study, we characterized the genomes of enteric MDR E. coli from pre-weaned dairy calves with and without diarrhea and evaluated the influence of host-level factors on genomic composition. Whole genome sequence comparative analysis of E. coli (n = 43) revealed substantial genomic diversity that primarily clustered by sequence type and was minimally driven by calf diarrheal disease status (healthy, diarrheic, or recovered), antimicrobial exposure, and dietary zinc supplementation. Diverse AMR genes (ARGs)-- including extended-spectrum beta-lactamase genes and quinolone resistance determinants--were identified (n = 40), with unique sets of ARGs co-occurring in gene clusters with large AMR plasmids IncA/C2 and IncFIB(AP001918). Zinc supplementation was not significantly associated with the selection of individual ARGs in E. coli, however analysis of ARG and metal resistance gene pairs identified positive associations between certain aminoglycoside, betalactam, sulfonamide, and trimethoprim ARGs with acid, tellurium and mercury resistance genes. Although E. coli in this study lacked the typical virulence factors of diarrheagenic strains, virulence genes overlapping with those in major pathotypes were identified. Among the 103 virulence genes detected, the highest abundance and diversity of genes corresponded to iron acquisition (siderophores and heme uptake). Our findings indicate that the host-level factors evaluated in this study were not key drivers of genomic variability, but that certain accessory genes in enteric MDR E. coli may be enriched. Collectively, this work provides insight into the genomic diversity and host-microbe interface of MDR E. coli from pre-weaned dairy calves. [ABSTRACT FROM AUTHOR]