Prevalence and Phylogenetic Characterization of Escherichia coli and Hygiene Indicator Bacteria Isolated from Leafy Green Produce, Beef, and Pork Obtained from Farmers' Markets in Pennsylvania

One Health Landscape of Antimicrobial Resistance in Bacteria Isolated from Virginia between 2007-2021

The emergence of antimicrobial-resistant (AMR) bacteria has become a critical global One Health issue, mainly attributed to the extensive use of antimicrobial agents in human and agricultural settings. Regional and local AMR surveillance data is essential for implementing awareness and mitigation strategies. This article assesses AMR frequency in 1604 bacterial isolates consisting of Escherichia coli (E. coli) and Salmonella spp. isolated from diverse sources in Virginia, including farm animals, wildlife, environment, and food samples from 2007 to 2021. The results are based on the Kirby-Bauer disc diffusion assessment method of susceptibility to select antimicrobial agents, spanning nine distinct categories approved by the US Food and Drug Administration for clinical use. Streptomycin (STR) and tetracycline (TCY) exhibited the highest frequency of resistance in E. coli (39.1%) and Salmonella (25.2%), respectively. Multidrug resistance (MDR) was evident in 6.6% of E. coli and 10.9% of Salmonella isolates. Notably, 51% of E. coli and 36% of Salmonella isolates demonstrated resistance to more than one antimicrobial. None of the tested antimicrobials guaranteed effectiveness against the bacteria isolated from the surveyed sources and regions. The study found heightened MDR and distinct AMR patterns in bacteria isolated from food products compared to other sampled sources. These findings are vital for comprehending the current AMR landscape, prompting the development of strategies to mitigate the emergence of AMR bacteria, and advocating prudent antimicrobial use from a One Health perspective.

Prevalence and Antimicrobial Characteristics of Escherichia coli in Selected Vegetables and Herbs in Bangkok, Thailand

Raw vegetables and herbs are exposure sources of foodborne pathogens. This study examined the prevalence and antimicrobial resistance of Escherichia coli in five types of fresh vegetables and herbs: spearmint (Mentha spicata), leaf lettuce (Lactuca sativa var. crispa), coriander (Coriandrum sativum), Chinese cabbage (Brassica rapa subsp. pekinensis), and cucumber (Cucumis sativus). Produce samples (n = 300) were acquired from local open markets and supermarkets in Bangkok, Thailand. Each produce sample was preenriched in buffered peptone water and then enriched in E. coli broth. A loopful of the second enrichment was transferred onto selective media for subsequent confirmation and biochemical tests. The Kirby-Bauer disk diffusion test was employed to assess E. coli susceptibility to selected antibiotics (twelve antibiotics of seven classes). The latex agglutination test was performed to serotype the isolates for O157 and H7 antigens. A commercial test kit was used to determine the presence of Shiga toxin-producing E. coli (STEC). For all samples, the prevalence of E. coli was found to be 32.0% (96/300), whereby produce from supermarkets had a higher prevalence than those from local markets at 40.7% (61/150) and 23.3% (35/150), respectively. Among different types of produce, leaf lettuce had the highest E. coli prevalence at 36.7% (22/60), followed by cucumber and spearmint, coriander, and Chinese cabbage, at 35.0% (21/60), 35.0% (21/60), 35.0% (21/60), and 18.3% (11/60), respectively. Of the positive isolates, 27.1% (26/96) showed multidrug resistance. All isolates (100%) showed resistance to penicillin but varying resistant characteristics for tetracycline, ampicillin, and amoxicillin, with resistance rates of 31.3% (30/96), 31.3% (30/96), and 31.3% (30/96), respectively. Two of the 96 isolates (1.1%) were positive for the O157 antigen but negative for the H7 antigen. No STEC was observed. This study established baseline information regarding the prevalence of E. coli and its antimicrobial resistance profile in produce in Bangkok, Thailand.

Hypervirulent clonal complex (CC) of Listeria monocytogenes in fresh produce from urban communities

Introduction

This study aimed to determine the prevalence and virulome of Listeria in fresh produce distributed in urban communities.

Methods

A total of 432 fresh produce samples were collected from farmer's markets in Michigan and West Virginia, USA, resulting in 109 pooled samples. Listeria spp. were isolated and L. monocytogenes was subjected to genoserogrouping by PCR and genotyping by pulsed-field gel electrophoresis (PFGE). Multi-locus sequence typing (MLST) and core-genome multi-locus sequence typing (cgMLST) were conducted for clonal identification.

Results

Forty-eight of 109 samples (44.0%) were contaminated with Listeria spp. L. monocytogenes serotype 1/2a and 4b were recovered from radishes, potatoes, and romaine lettuce. Four clonal complexes (CC) were identified and included hypervirulent CC1 (ST1) and CC4 (ST219) of lineage I as well as CC7 (ST7) and CC11 (ST451) of lineage II. Clones CC4 and CC7 were present in the same romaine lettuce sample. CC1 carried Listeria pathogenicity island LIPI-1 and LIPI-3 whereas CC4 contained LIPI-1, LIPI-3, and LIPI-4. CC7 and CC11 had LIPI-1 only.

Discussion

Due to previous implication in outbreaks, L. monocytogenes hypervirulent clones in fresh produce pose a public health concern in urban communities.

Prevalence of Escherichia coli generic and pathogenic in pork meat: systematic review and meta-analysis

This research aimed to analyze scientific information regarding the prevalence of generic and pathogenic E. coli in the production and supply chain of pork meat, considering different types of samples, places of sampling, and pathotypes using a systematic review and meta-analysis tools. The meta-analysis for the prevalence of generic and pathogenic E. coli was conducted by estimating the effects within subgroups. Data subsets were analyzed using the DerSimonian-Laird method for binary random effects. The average prevalence of generic E. coli in different types of pork meat samples was determined to be 35.6% (95% CI 19.3-51.8), with no significant differences observed between pork meat and carcasses. Conversely, the average prevalence of E. coli pathotypes in samples related to the supply chain of pork meat was found to be 4.7% (95% CI 3.7-5.7). In conclusion, these findings suggest the possibility of establishing an objective threshold for E. coli prevalence as a benchmark for comparison within the meat industry. By utilizing this data, it becomes possible to propose a standardized limit that can serve as a reference point for evaluating and improving processes in the industry.

Antimicrobial Resistant Pathogens Detected in Raw Pork and Poultry Meat in Retailing Outlets in Kenya

There is increasing proof of bacterial resistance to antibiotics all over the world, and this puts the effectiveness of antimicrobials that have been essential in decreasing disease mortality and morbidity at stake. The WHO has labeled some classes of antimicrobials as vitally important to human health. Bacteria from animals are thought to be reservoirs of resistance genes that can be transferred to humans through the food chain. This study aimed to identify the resistance patterns of bacteria from pork and poultry meat samples purchased from leading retail outlets in Kenya. Of the 393 samples collected, 98.4% of pork and 96.6% of poultry were contaminated with high levels of bacteria. Among the 611 bacterial isolates recovered, 38.5% were multi-drug resistant. This resistance was noted for critically essential antimicrobials (according to the WHO) such as rifampicin (96%), ampicillin (35%), cefotaxime (9%), cefepime (6%), and ciprofloxacin (6%). Moreover, there was high resistance to key antimicrobials for veterinary medicine such as tetracycline (39%), sulfamethoxazole (33%), and trimethoprim (30%). It is essential to spread awareness about the judicious use of antibiotics and take preventive measures to reduce disease burden.

Microbiological analysis and characterization of Salmonella and ciprofloxacin-resistant Escherichia coli isolates recovered from retail fresh vegetables in Shaanxi Province, China

Fresh vegetables are closely associated with foodborne disease outbreaks; however, systematic analysis of the microbiological quality of fresh vegetables and molecular information on foodborne pathogens in fresh produce are poorly reported in China. Here, we evaluated the epidemiological prevalence of coliforms via the most probable number method and characterized Salmonella and ciprofloxacin-resistant (CIP^R) Escherichia coli isolates recovered from retail fresh vegetables in Shaanxi Province, China. Antimicrobial susceptibility testing, serotype determination, multilocus sequence typing (MLST), core genome multilocus sequence typing (cgMLST), antibiotic resistance encoding gene (ARG) annotation, virulence factor prediction, and functional classification were performed. Between October 2020 and September 2021, 576 samples (i.e., tomatoes, lettuces, spinaches, and cabbages) were found to be positive for coliforms, and the prevalence of coliforms showed a seasonal trend. Coliform counts of vegetables in supermarkets in Xi'an were significantly lower (P < 0.01) than that in other cities. The detection rates of Salmonella and CIP^RE. coli-positive vegetables were 1 % (6/576) and 0.7 % (4/576), respectively. All isolates exhibited resistance to ≥1 antibiotics, and 92.9 % (13/14) were multidrug-resistant. One extended spectrum β-lactamase (ESBL)-producing CIP^RE. coli isolate in spinach was resistant to not only three third-generation cephalosporins but also to two polymyxins. Among nine Salmonella isolates, five different serovars (S. Enteritidis, S. Indiana, monophasic variant of S. Typhimurium, S. Agona, and S. Gallinarum), four sequence types (STs; ST11, ST13, ST17, and ST34), and seven core genome STs (cgSTs) were identified. Five CIP^RE. coli strains were assigned to three serovars (O101:H4, O8:H18, and O11:H25), three STs (ST44, ST48, and ST457), and four cgSTs. Coexisting amino acid mutations of Thr57Ser/Ser80Arg in ParC and Ser83Phe/Asp87Gly in GyrA in quinolone resistance-determining regions (QRDRs) might be causes for nalidixic acid resistance. Eight definite virulence profiles in eight serovars were identified. Notably, cdtB and pltA only encoded typhoid toxins and were just detected from S. Typhoid isolates were also detected from S. Indiana and monophasic S. Typhimurium, which are closely associated with swine food chain were first detected in fresh vegetables. In conclusion, our findings suggest that coliform contamination on fresh vegetables is prevalent in this province. Most Salmonella and CIP^RE. coli isolates were phenotypically and genetically diverse and could resist multiple antibiotics by carrying multiple ARGs and virulence genes.

Accelerating the Detection of Bacteria in Food Using Artificial Intelligence and Optical Imaging

In assessing food microbial safety, the presence of Escherichia coli is a critical indicator of fecal contamination. However, conventional detection methods require the isolation of bacterial macrocolonies for biochemical or genetic characterization, which takes a few days and is labor-intensive. In this study, we show that the real-time object detection and classification algorithm You Only Look Once version 4 (YOLOv4) can accurately identify the presence of E. coli at the microcolony stage after a 3-h cultivation. Integrating with phase-contrast microscopic imaging, YOLOv4 discriminated E. coli from seven other common foodborne bacterial species with an average precision of 94%. This approach also enabled the rapid quantification of E. coli concentrations over 3 orders of magnitude with an R² of 0.995. For romaine lettuce spiked with E. coli (10 to 10³ CFU/g), the trained YOLOv4 detector had a false-negative rate of less than 10%. This approach accelerates analysis and avoids manual result determination, which has the potential to be applied as a rapid and user-friendly bacterial sensing approach in food industries. IMPORTANCE A simple, cost-effective, and rapid method is desired to identify potential pathogen contamination in food products and thus prevent foodborne illnesses and outbreaks. This study combined artificial intelligence (AI) and optical imaging to detect bacteria at the microcolony stage within 3 h of inoculation. This approach eliminates the need for time-consuming culture-based colony isolation and resource-intensive molecular approaches for bacterial identification. The approach developed in this study is broadly applicable for the identification of diverse bacterial species. In addition, this approach can be implemented in resource-limited areas, as it does not require expensive instruments and significantly trained human resources. This AI-assisted detection not only achieves high accuracy in bacterial classification but also provides the potential for automated bacterial detection, reducing labor workloads in food industries, environmental monitoring, and clinical settings.

Microbiota Analysis and Microbiological Hazard Assessment in Chinese Chive (Allium tuberosum Rottler) Depending on Retail Types

Chinese chive (Allium tuberosum Rottler) has potential risks associated with pathogenic bacterial contamination as it is usually consumed raw. In this study, we investigated the microbiota of Chinese chives purchased from traditional markets and grocery stores in March (Spring) and June (Summer) 2017. Differences in bacterial diversity were observed, and the microbial composition varied across sampling times and sites. In June, potential pathogenic genera, such as Escherichia, Enterobacter, and Pantoea, accounted for a high proportion of the microbiota in samples purchased from the traditional market. A large number of pathogenic bacteria (Acinetobacter lwoffii, Bacillus cereus, Klebsiella pneumoniae, and Serratia marcescens) were detected in the June samples at a relatively high rate. In addition, the influence of the washing treatment on Chinese chive microbiota was analyzed. After storage at 26°C, the washing treatment accelerated the growth of enterohemorrhagic Escherichia coli (EHEC) because it caused dynamic shifts in Chinese chive indigenous microbiota. These results expand our knowledge of the microbiota in Chinese chives and provide data for the prediction and prevention of food-borne illnesses.

Phylogenetic Groups and Antimicrobial Resistance Genes in Escherichia coli from Different Meat Species

Escherichia coli isolated from meat of different animal species may harbour antimicrobial resistance genes and may thus be a threat to human health. The objectives of this study were to define antimicrobial resistance genes in E. coli isolates from pork, beef, chicken- and turkey meat and analyse whether their resistance genotypes associated with phylogenetic groups or meat species. A total number of 313 E. coli samples were isolated using standard cultural techniques. In 98% of resistant isolates, a dedicated resistance gene could be identified by PCR. Resistance genes detected were tet(A) and tet(B) for tetracycline resistance, strA and aadA1 for streptomycin resistance, sulI and sulII for resistance against sulphonamides, dfr and aphA for kanamycin resistance and bla_TEM for ampicillin resistance. One stx1 harbouring E. coli isolated from pork harboured the tet(A) gene and belonged to phylogenetic group B2, whilst another stx1 positive isolate from beef was multi-resistant and tested positive for bla_TEM,aphA, strA–B, sulII, and tet(A) and belonged to phylogenetic group A. In conclusion, the distribution of resistance elements was almost identical and statistically indifferent in isolates of different meat species. Phylogenetic groups did not associate with the distribution of resistance genes and a rather low number of diverse resistance genes were detected. Most E. coli populations with different resistance genes against one drug often revealed statistically significant different MIC values.

Food Safety in Local Farming of Fruits and Vegetables

The world’s population will be around 9 billion people by 2050. Humans need to feed in order to survive and thus the high demographic growth may impact the sustainability of our food systems. Sustainable food production practices such as local farming have been explored. Consumption of vegetables and fruits has been increasing due to their health benefits, but this increase is also related to a significant number of foodborne outbreaks. Foodborne outbreaks pose a threat to public health and the economy on a local and national scale. Food safety begins on the farm and proceeds over the supply chain. Thus, to provide safe products, food producers must follow specific procedures to avoid food hazards along the supply chain. This work aimed to present the importance of food safety in vegetables and fruits in local farming, as this form of production and consumption has increased in several countries of the northern hemisphere and as these are considered a form of providing more sustainable food products.

Emergence and Clonal Spread of CTX-M-65-Producing Escherichia coli From Retail Meat in Portugal

The emergence and dissemination of resistance to third- and fourth-generation cephalosporins among Enterobacteriaceae from different sources impose a global public health threat. Here, we characterized by whole-genome sequencing four Escherichia coli strains harboring the bla_CTX–M–65 gene identified among 49 isolates from beef and pork collected at retail. The genomic content was determined using the Center for Genomic Epidemiology web tools. Additionally, the prediction and reconstruction of plasmids were conducted, the genetic platform of the bla_CTX–M–65 genes was investigated, and phylogenetic analysis was carried out using 17 other genomes with the same sequence type and harboring the bla_CTX–M–65 gene. All strains harbored bla_CTX–M–65, bla_OXA–1, and bla_TEM–1B, and one also carried the bla_SHV–12 gene. Other resistance genes, namely, qnrS2, aac(6′)-Ib-c, dfrA14, sul2, tetA, and mphA, were present in all the genomes; the mcr-1.1 gene was identified in the colistin-resistant strains. They belong to sequence type 2179, phylogenetic group B1, and serotype O9:H9 and carried plasmids IncI, IncFIC(FII), and IncFIB. All strains share an identical genetic environment with IS903 and ISEcp1 flanking the bla_CTX–M–65 gene. It seems likely that the bla_CTX–M–65 gene is located in the chromosome in all isolates based on deep in silico analysis. Our findings showed that the strains are clonally related and belong to two sub-lineages. This study reports the emergence of CTX-M-65-producing E. coli in Portugal in food products of animal origin. The chromosomal location of the bla_CTX–M–65 gene may ensure a stable spread of resistance in the absence of selective pressure.

A Systematic Review of Listeria Species and Listeria monocytogenes Prevalence, Persistence, and Diversity throughout the Fresh Produce Supply Chain

Listeria monocytogenes is an increasing food safety concern throughout the produce supply chain as it has been linked to produce associated outbreaks and recalls. To our knowledge, this is the first systematic literature review to investigate Listeria species and L. monocytogenes prevalence, persistence, and diversity at each stage along the supply chain. This review identified 64 articles of 4863 candidate articles obtained from four Boolean search queries in six databases. Included studies examined naturally detected/isolated Listeria species and L. monocytogenes in fresh produce-related environments, and/or from past fresh produce associated outbreaks or from produce directly. Listeria species and L. monocytogenes were detected in each stage of the fresh produce supply chain. The greatest prevalence of Listeria species was observed in natural environments and outdoor production, with prevalence generally decreasing with each progression of the supply chain (e.g., packinghouse to distribution to retail). L. monocytogenes prevalence ranged from 61.1% to not detected (0.00%) across the entire supply chain for included studies. Listeria persistence and diversity were also investigated more in natural, production, and processing environments, compared to other supply chain environments (e.g., retail). Data gaps were identified for future produce safety research, for example, in the transportation and distribution center environment.

The effect of vegetation barriers at reducing the transmission of Salmonella and Escherichia coli from animal operations to fresh produce

Due to the recent outbreaks of Salmonella and Escherichia coli in fresh produce in the United States, the transfer of foodborne pathogens between animal feeding operations and fresh produce continues to be a considerable risk. The purpose of this study was to determine if the establishment of a vegetation barrier (VB) on small-scale sustainable farms could prevent the transmission of Salmonella and E. coli to nearby fresh produce fields. A 5-layer VB (31 × 49 m) was constructed between a dairy farm, a poultry farm, and a nearby produce field. Fresh produce (i.e., romaine lettuce and tomato), animal feces, and environmental (i.e., air, soil, and barrier) samples were collected for 15 months from 2018 to 2019. Four replicates of soil and fresh produce samples were taken from three plots located 10 m, 61 m, and 122 m away from the respective animal locations and processed for Salmonella and E. coli. Air and vegetative strip samples were sampled at 15-day intervals. Multiple colonies were processed from each positive sample, and a total of 143 positive Salmonella (n = 15) and E. coli (n = 128) isolates were retrieved from the soil, produce, air, and fecal samples. Interestingly, 18.2% of the Salmonella and E. coli isolates (n = 26) were recovered from fresh produce (n = 9) samples. Surprisingly, Salmonella isolates (n = 9) were only found in fecal (n = 3) samples collected from the dairy pasture. Data analysis suggests that the VB is an effective tool at reducing the transmission of E. coli and Salmonella from animal farms to fresh produce fields. However, based on phenotypic and genotypic testing, it is clear that fecal samples from animal farms are not the only source of pathogen contamination. This indicates that the environment (e.g., soil and wind), as well as the initial setup of the farm (e.g., proximity to service roads and produce plot placement), can contribute to the contamination of fresh produce. Our study recommends the need for more effective bioremediation and prevention control measures to use in conjunction with VBs to reduce pathogen transmission.

High prevalence of multidrug resistant Escherichia coli isolated from fresh vegetables sold by selected formal and informal traders in the most densely populated Province of South Africa

Contaminated fresh produce has increasingly been implicated in foodborne disease outbreaks. As microbiological safety surveillance in South Africa is limited, a total of 545 vegetable samples (spinach, tomato, lettuce, cucumber, and green beans) were purchased from retailers, street traders, trolley vendors and farmers' markets. Escherichia coli, coliforms and Enterobacteriaceae were enumerated and the prevalence of Escherichia coli, Salmonella spp. and Listeria monocytogenes determined. E. coli isolates were characterized phenotypically (antibiotic resistance) and genotypically (diarrheagenic virulence genes). Coliforms, E. coli and Enterobacteriaceae counts were mostly not significantly different between formal and informal markets, with exceptions noted on occasion. When compared to international standards, 90% to 98% tomatoes, 70% to 94% spinach, 82% cucumbers, 93% lettuce, and 80% green bean samples, had satisfactory (≤ 100 CFU/g) E. coli counts. Of the 545 vegetable samples analyzed, 14.86% (n = 81) harbored E. coli, predominantly from leafy green vegetables. Virulence genes (lt, st, bfpA, eagg, eaeA, stx1, stx2, and ipaH) were not detected in the E. coli isolates (n = 67) characterized, however 40.30% were multidrug-resistant. Resistance to aminoglycosides (neomycin, 73.13%; gentamycin, < 10%), penicillins (ampicillin, 38.81%; amoxicillin, 41.79%; augmentin, < 10%), sulfonamides (cotrimoxazole, 22.39%), tetracycline (19.4%), chloramphenicol (11.94%), cephalosporins (cefepime, 34.33%), and carbapenemases (imipenem, < 10%) were observed. This study highlights the need for continued surveillance of multidrug resistant foodborne pathogens in fresh produce retailed formally and informally for potential consumer health risks. PRACTICAL APPLICATION: The results indicate that the microbiological quality of different vegetables were similar per product type, regardless of being purchased from formal retailers or informal street traders, trolley vendors or farmers' markets. Although no pathogenic bacteria (diarrheagenic E. coli, Salmonella spp. or L. monocytogenes) were isolated, high levels of multidrug-resistance was observed in the generic E. coli isolates. These findings highlight the importance of microbiological quality surveillance of fresh produce in formal and informal markets, as these products can be a reservoir of multidrug resistant bacteria harboring antibiotic resistance and virulence genes, potentially impacting human health.

Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolated from Fresh Produce and Agricultural Environments in Korea

ABSTRACT

This study was conducted to characterize Escherichia coli strains and evaluate the spread of antimicrobial resistance among these strains from fresh produce and farm environments in Korea. We then conducted phenotypic and genetic studies on antimicrobial-resistant isolates. We determined the genetic epidemiological characteristics of isolates that produced extended-spectrum β-lactamase (ESBL) and confirmed plasmid transfer in isolates that carried blaCTX-M-type genes. E. coli strains were isolated from 8 samples of fresh produce and 152 samples from the farm environment collected from May 2014 to June 2016. Cephalosporin resistance was the most prevalent (61.8%) type of resistance among the isolates. Five ESBL-producing strains with high genetic homology with E. coli of human or livestock origin were identified. Lateral transfer of plasmids harboring blaCTX-M-type genes to transconjugants was successful. Two isolates from Chinese cabbage and from water samples collected from a nearby stream harbored the ISEcp1-blaCTX-M-55-orf477 operon and were confirmed as sequence type 1196 and the same type of plasmid replicon, suggesting that cross-contamination was highly likely. A high-risk clone of sequence type 69 (clonal complex 69) isolates was also recovered from the farm environment. This study provides genetic evidence that antimicrobial resistance factors in E. coli from farm environments originate in the clinic or in livestock, highlighting the fact that good agricultural practices in farming are important to inhibit the spread of antimicrobial resistance to bacteria on fresh produce.

HIGHLIGHTS

Preserving US microbe collections sparks future discoveries

Collections of micro‐organisms are a crucial element of life science research infrastructure but are vulnerable to loss and damage caused by natural or man‐made disasters, the untimely death or retirement of personnel, or the loss of research funding. Preservation of biological collections has risen in priority due to a new appreciation for discoveries linked to preserved specimens, emerging hurdles to international collecting and decreased funding for new collecting. While many historic collections have been lost, several have been preserved, some with dramatic rescue stories. Rescued microbes have been used for discoveries in areas of health, biotechnology and basic life science. Suggestions for long‐term planning for microbial stocks are listed, as well as inducements for long‐term preservation.

Molecular Characterization of Multidrug-Resistant Escherichia coli Isolates from Edible Offal in Korea

HIGHLIGHTS

Edible offal is significantly contaminated by antimicrobial-resistant Escherichia coli. E. coli from edible offal is harboring various antimicrobial resistance and virulence genes. Improvements in hygienic conditions of edible offal production is required.

Influence of acidified drinking water on growth performance and gastrointestinal function of broilers

The ban on the use of antibiotic feed additives as growth promoters compelled the researchers for exploring the future utility of other alternatives. This experiment was designed to evaluate the effect of acidified drinking water on growth performance, gastrointestinal pH, digestive enzymes, intestinal histomorphology, and cecum microbial counting of the broiler chicken. A total of 540 one-day-old male broilers (Arbor Acre) were randomly assigned to 5 treatments, with 6 replicates of 18 chicks per replicate. Broilers received diets and water as follows: NC (negative control, basal diet, normal water), PC (positive control, basal diet + 8 ppm colistin sulfate + 8 ppm enduracidin, normal water), A1 (basal diet, continuous supply of acidified water during whole experiment period), A2 (basal diet, intermittent acidification of water during 0 to 14 d, 22 to 28 d, and 36 to 42 d), and A3 [basal diet, intermittent acidification of water (24 h/d from 0 to 14 d and from 10:00 am to 4:00 pm on d 15 to 42)]. During the entire period, the acidified groups (A1, A2, and A3) and PC group showed improve on weight gain, average daily gain and feed conversion ratio compared to NC group (P < 0.05). The pH in crop, proventriculus and ileum at 43 d declined by 0.04, 1.03, 1.23; 0.55, 0.69, 0.70; and 0.63, 0.74, 1.21 in A1, A2, and A3 group, respectively. There was a significant decline of lipase activity in the PC and acidified groups compared to NC group. The A2 group had higher villus height in jejunum than NC group. The PC and acidified groups reduced (P < 0.05) the total aerobic bacteria count of cecum when contrasted to NC group. Therefore, we conclude that acidified drinking water can improve growth performance, compensate for gastric acidity, and control pathogenic bacteria in broilers and may be considered as a potential alternative to improve production parameters. Discontinuous supply of acidified water had the same or even better influence on broilers compared to continuous supply.

Rapid Detection of Escherichia coli in Fresh Foods Using a Combination of Enrichment and PCR Analysis

The objective of this study was to determine the minimum enrichment time for different types of food matrix (pork, beef, and fresh-cut lettuce) in an effort to improve Escherichia coli detection efficiency. Fresh pork (20 g), beef (20 g), and fresh-cut lettuce (20 g) were inoculated at 1, 2, and 3 Log CFU/g of Escherichia coli. Samples were enriched in filter bags for 3 or 5 h at 44.5°C, depending on sample type. E. coli cell counts in the samples were enriched in E. coli (EC) broth at 3 or 5 h. One milliliter of the enriched culture medium was used for DNA extraction, and PCR assays were performed using primers specific for uidA gene. To detect E. coli (uidA) in the samples, a 3-4 Log CFU/mL cell concentration was required. However, E. coli was detected at 1 Log CFU/g in fresh pork, beef, and fresh-cut lettuce after 5, 5, and 3-h enrichment, respectively. In conclusion, 5-h enrichment for fresh meats and 3-h enrichment for fresh-cut lettuce in EC broth at 44.5°C, and PCR analysis using uidA gene-specific primers were appropriate to detect E. coli rapidly in food samples.

Spread of multidrug-resistant Escherichia coli harboring integron via swine farm waste water treatment plant

Wastewater treatment plants (WWTPs) that release treated wastewater into the environment have emerged as a major threat to public health. In this study, we investigated Escherichia coli load and antibiotic-resistance profiles across different treatment processes at a swine farm WWTP. The frequency of the detection of class 1 and 2 integrons, and their association with antibiotic resistance, were also analyzed. Samples were obtained at each of five sampling sites that represented each processing step within the WWTP. The largest decrease in E. coli load was observed during the anaerobic digestion step (from 4.86 to 2.89log CFU/mL). Isolates resistant to β-lactam antibiotics were efficiently removed after a series of treatment steps, whereas the proportions of isolates resistant to non-β-lactam antibiotics and multidrug-resistant strains were maintained across treatments. The occurrence of integron-positive strains was not significantly different at the various sampling sites (43.4-70%; p>0.05). Of the class 1 integron-positive isolates, 17.9% harbored the integron-associated gene cassettes aadA2, aadA12, aadA22, and dfrA15. To the best of our knowledge, this is the first description of a class 1 integron containing the aadA12 gene cassette from a swine farm and the presence of a class 1 integron containing dfrA15 in E. coli. This suggests that novel antibiotic-resistance gene cassette arrays could be generated in swine farm WWTPs. Moreover, 75% of integron-positive strains were categorized as multidrug resistant, whereas only 15.4% of integron-negative strains were multidrug resistant (p<0.05), indicating that integrons may be responsible for mediating resistance in WWTPs. With regard to the occurrence of multidrug-resistant, integron-positive E. coli recovered from the final effluent, our results highlighted the potential risks associated with wastewater discharge from swine farm WWTPs in terms of the spread of antibiotic-resistant bacteria to the aquatic environment.