Antimicrobial resistance in E. coli isolates from conventionally and organically reared poultry: A comparison of agar disc diffusion and Sensi Test Gram-negative methods

Inhibitory Effects of Lactobionic Acid on Biofilm Formation and Virulence of Staphylococcus aureus

Staphylococcus aureus biofilm is a common bio-contaminant source that leads to food cross-contamination and foodborne disease outbreaks. Hence, there is a need for searching novel antibiofilm agents with potential anti-virulence properties to control S. aureus contamination and infections in food systems. In this study, the antibiofilm effects of lactobionic acid (LBA) against S. aureus and its influence on virulence were explored. The minimum inhibition concentration of LBA on S. aureus was 8 mg/mL. Viable count and crystal violet assays revealed that LBA inhibited and inactivated S. aureus biofilms. Microscopic observations further confirmed the antibiofilm activity of LBA on S. aureus that disrupted the biofilm architecture and inactivated the viable cells in biofilms. Moreover, LBA decreased the release of extracellular DNA (eDNA) and extracellular polysaccharide (EPS) in S. aureus biofilms. LBA suppressed biofilm formation by intervening metabolic activity and reduced virulence secretion by repressing the hemolytic activity of S. aureus. Furthermore, LBA altered the expressions of biofilm- and virulence-related genes in S. aureus, further confirming that LBA suppressed biofilm formation and reduced the virulence secretion of S. aureus. The results suggest that LBA might be useful in preventing and controlling biofilm formation and the virulence of S. aureus to ensure food safety.

Comparative Antimicrobial Resistance and Prevalence of Methicillin Resistance in Coagulase-Positive Staphylococci from Conventional and Organic Dairy Farms in South Korea

Bovine mastitis (BM) has caused huge economic and financial losses in the dairy industry worldwide, with Staphylococcus aureus as one of its major pathogens. BM treatment still relies on antibiotics and its extensive use often generates methicillin-resistant S. aureus (MRSA) and mupirocin-resistant S. aureus (MuRSA). This study compared the antimicrobial resistance trend in coagulase-positive Stapholococci (CoPS) isolated from BM milk in conventional and organic dairy farms and checked prevalence of MRSA and MuRSA. A total of 163 presumptive Staphylococci were isolated, wherein 11 out of 74 from 4 conventional farms (CF1, CF2, CF3, CF4) and 17 out of 89 from 3 organic farms (OF1, OF2, OF3) exhibited coagulase activity. Multiplex-PCR amplification confirmed at least one coagulase-positive isolate from CF1, CF2, CF3, CF4, and OF1 as S. aureus, denoted by the presence of the nuc gene. Three isolates from CF2 contained the mecA gene, indicating MRSA prevalence, while the MuRSA gene marker, mupA, was not detected in any of the isolates. Antimicrobial testing showed that conventional farm isolates were more resistant to antibiotics, especially ampicillin and tetracycline. This suggests a risk of developing multidrug resistance in dairy farms if antibiotic use is not properly and strictly monitored and regulated.

Viability and Virulence of Listeria monocytogenes in Poultry

The prevalence of Listeria monocytogenes in 30 samples of poultry was determined using culture-dependent (isolation on OCLA and confirmation by conventional polymerase chain reaction -PCR-, OCLA&PCR) and culture-independent (real-time polymerase chain reaction, q-PCR) methods. L. monocytogenes was detected in 15 samples (50.0%) by OCLA&PCR and in 20 (66.7%) by q-PCR. The concentrations (log10 cfu/g) of L. monocytogenes (q-PCR) ranged from 2.40 to 5.22 (total cells) and from <2.15 to 3.93 (viable cells). The two methods, q-PCR using a viability marker (v-PCR) and OCLA&PCR (gold standard), were compared for their capacity to detect viable cells of L. monocytogenes, with the potential to cause human disease. The values for sensitivity, specificity and efficiency of the v-PCR were 100%, 66.7% and 83.3%, respectively. The agreement between the two methods (kappa coefficient) was 0.67. The presence of nine virulence genes (hlyA, actA, inlB, inlA, inlC, inlJ, prfA, plcA and iap) was studied in 45 L. monocytogenes isolates (three from each positive sample) using PCR. All the strains harbored between six and nine virulence genes. Fifteen isolates (33.3% of the total) did not show the potential to form biofilm on a polystyrene surface, as determined by a crystal violet assay. The remaining strains were classified as weak (23 isolates, 51.1% of the total), moderate (one isolate, 2.2%) or strong (six isolates, 13.3%) biofilm producers. The strains were tested for susceptibility to a panel of 15 antibiotics. An average of 5.11 ± 1.30 resistances per isolate was observed. When the values for resistance and for reduced susceptibility were taken jointly, this figure rose to 6.91 ± 1.59. There was a prevalence of resistance or reduced susceptibility of more than 50.0% for oxacillin, cefoxitin, cefotaxime, cefepime ciprofloxacin, enrofloxacin and nitrofurantoin. For the remaining antibiotics tested, the corresponding values ranged from 0.0% for chloramphenicol to 48.9% for rifampicin. The high prevalence and level of L. monocytogenes with numerous virulence factors in poultry underline how crucial it is to follow correct hygiene procedures during the processing of this foodstuff in order to reduce the risk of human listeriosis.

Microbiological Quality and Safety of Fresh Quail Meat at the Retail Level

The objective of this study was to evaluate the microbiological quality and safety of 37 fresh quail meats. Mesophiles, Pseudomonas spp., Enterobacteriaceae, and staphylococci counts were 5.25 ± 1.14, 3.92 ± 1.17, 3.09 ± 1.02, and 2.80 ± 0.64 log CFU/g, respectively. Listeria monocytogenes was detected in seven samples (18.92%). Campylobacter jejuni was detected in one sample (2.70%). Clostridium perfringens was not detected in any sample. The dominant bacteria were Pseudomonas spp. (30.46%), Micrococcaceae (19.87%), lactic acid bacteria (14.57%), and Enterobacteriaceae (11.92%). Brochotrix thermosphacta and enterococci were isolated to a lesser extent, 7.28% and 1.99%, respectively. The dominant Enterobacteriaceae found were Escherichia coli (42.53%). ESBL-producing E. coli was detected in one sample (2.70%), showing resistance to 16 antibiotics. Sixteen different Staphylococcus spp. and three Mammaliicoccus spp. were identified, the most common being S. cohnii (19.86%) and M. sciuri (17.02%). S. aureus and S. epidermidis were also found in one and four samples, respectively. Methicillin-resistant M. sciuri and S. warneri were found in 13.51% and 10.81% of quail samples, respectively. These bacteria showed an average of 6.20 and 18.50 resistances per strain, respectively. The high resistance observed in ESBL-producing E. coli and methicillin-resistant S. warneri is of special concern. Measures should be adopted to reduce the contamination of quail meat.

Evaluating Antimicrobial Resistance Trends in Commensal Escherichia coli Isolated from Cecal Samples of Swine at Slaughter in the United States, 2013-2019

The emergence of antimicrobial resistance (AMR) in commensal and pathogenic enteric bacteria of swine is a public health threat. This study evaluated publicly available AMR surveillance data collected by the National Antimicrobial Resistance Monitoring System (NARMS) by assessing AMR patterns and temporal trends in commensal E. coli isolated from cecal samples of swine at slaughter across the United States. We applied the Mann-Kendall test (MKT) and a linear regression trend line to detect significant trends in the proportion of resistant isolates to individual antimicrobials over the study period. A Poisson regression model assessed differences among years in the number of antimicrobials to which an E. coli isolate was resistant. Among the 3237 E. coli isolates, a very high prevalence of resistance for tetracycline (67.62%), and high resistance for streptomycin (24.13%), and ampicillin (21.10%) were identified. The MKT and the linear trend line showed a significantly increasing temporal trend for amoxicillin-clavulanic acid, ampicillin, azithromycin, cefoxitin, ceftriaxone, and trimethoprim-sulfamethoxazole. Compared to 2013 the number of antimicrobials to which an E. coli isolate was resistant was significantly higher in the years 2017, 2018, and 2019. The increasing temporal trend of resistance to important antimicrobials for human medicine (e.g., third-generation cephalosporins) and the increase in multidrug resistance in the later years of the study are concerning and should be followed up by studies to identify sources and risk factors for the selection of AMR.

Promising antimicrobial and antibiofilm activities of Orobanche aegyptiaca extract-mediated bimetallic silver-selenium nanoparticles synthesis: Effect of UV-exposure, bacterial membrane leakage reaction mechanism, and kinetic study

In this research, Orobanche aegyptiaca extract was utilized as an eco-friendly, and cost-effective green route for the construction of bimetallic silver-selenium nanoparticles (Ag-Se NPs). Bimetallic Ag-Se NPs were characterized by XRD, EDX, FTIR, HR-TEM, DLS, SEM/mapping and EDX studies. Antimicrobial, and antibiofilm potentials were tested against some selected pathogenic bacteria and unicellular fungi by ZOI, MIC, effect of UV exposure, and inhibition %. Reaction mechanism was assessed through membrane leakage assay and SEM imaging. HRTEM analysis confirmed the spherical nature and was ranged from 18.1 nm to 72.0 nm, and the avarage particle size is determined to be 30.58 nm. SEM imaging prove that bimetallic Ag-Se NPs presents as a bright particles, and both Ag and Se were distributed equally across O. aegyptiaca extract and Guar gum stabilizers. ZOI results showed that, bimetallic Ag-Se NPs have antimicrobial activity against S. aureus (20.0 nm), E. coli (18.5 nm), P. aeruginosa (12.6 nm), and C. albicans (18.2 nm). In addition, bimetallic Ag-Se NPs were able to inhibit the biofilm formation for S. aureus by 79.48%, for E. coli by 78.79%, for P. aeruginosa by 77.50%, and for C. albicans by 73.73%. Bimetallic Ag-Se NPs are an excellent disinfectant once it had excited by UV light. It was observed that the quantity of cellular protein discharged from S. aureus is directly proportional to the concentration of bimetallic Ag-Se NPs and found to be 244.21 μg/mL after the treatment with 1 mg/mL, which proves the antibacterial characteristics, and explains the creation of holes in the cell membrane of S. aureus producing in the oozing out of the proteins from the S. aureus cytoplasm. Based on the promising properties, they showed superior antimicrobial potential at low concentration (to avoid toxicity) and continued-phase durability, they may use in pharmaceutical and biomedical applications.

Distribution pattern of antibiotic resistance genes in Escherichia coli isolated from colibacillosis cases in broiler farms of Egypt

Background and Aim

Multidrug resistance (MDR) of Escherichia coli has become an increasing concern in poultry farming worldwide. However, E. coli can accumulate resistance genes through gene transfer. The most problematic resistance mechanism in E. coli is the acquisition of genes encoding broad-spectrum β-lactamases, known as extended-spectrum β-lactamases, that confer resistance to broad-spectrum cephalosporins. Plasmid-mediated quinolone resistance genes (conferring resistance to quinolones) and mcr-1 genes (conferring resistance to colistin) also contribute to antimicrobial resistance. This study aimed to investigate the prevalence of antimicrobial susceptibility and to detect β-lactamase and colistin resistance genes of E. coli isolated from broiler farms in Egypt.

Materials and Methods

Samples from 938 broiler farms were bacteriologically examined for E. coli isolation. The antimicrobial resistance profile was evaluated using disk diffusion, and several resistance genes were investigated through polymerase chain reaction amplification.

Results

Escherichia coli was isolated and identified from 675/938 farms (72%) from the pooled internal organs (liver, heart, lung, spleen, and yolk) of broilers. Escherichia coli isolates from the most recent 3 years (2018-2020) were serotyped into 13 serotypes; the most prevalent serotype was O125 (n = 8). The highest phenotypic antibiotic resistance profiles during this period were against ampicillin, penicillin, tetracycline, and nalidixic acid. Escherichia coli was sensitive to clinically relevant antibiotics. Twenty-eight selected isolates from the most recent 3 years (2018-2020) were found to have MDR, where the prevalence of the antibiotic resistance genes ctx, tem, and shv was 46% and that of mcr-1 was 64%. Integrons were found in 93% of the isolates.

Conclusion

The study showed a high prevalence of E. coli infection in broiler farms associated with MDR, which has a high public health significance because of its zoonotic relevance. These results strengthen the application of continuous surveillance programs.

Gamma Radiation Induced Synthesis of Novel Chitosan/Gold/Bioactive Glass Nanocomposite for Promising Antimicrobial, and Antibiofilm Activities

In the present study we reported, for the first time, the gamma irradiation induced synthesis of chitosan/Au/bioactive glass (CS/Au/BG) nanocomposite. The bioactive glass (BG), with the composition 45% SiO2, 32.5% CaO, 15% Na2O, and 7.5% P2O5 wt% was synthesized through the sol–gel technique. XRD, SEM, EDX, and elemental mapping images were utilized to evaluate the structure of pure BG and CS/Au/BG nanocomposite. The antimicrobial efficacy was evaluated by zone of inhibition (ZOI), minimum inhibitory concentration (MIC), growth curve assay, and Ultraviolet irradiation effect. Investigation was carried on the antibiofilm effectiveness. Membrane leakage as well as SEM imaging were used to evaluate the antibacterial reaction mechanism. The crystallite size of CS/Au/BG nanocomposite was determined via Scherer equation as 22.83 nm. CS/Au/BG possessed the most ZOI activity against the tested microbes. The highest inhibition % of BG, and CS/Au/BG nanocomposite was investigated for S. aureus (15.65%, and 77.24%), followed by C. albicans (13.32%, and 64.75%). The quantity of protein leakage was directly-proportional after increasing the concentration of BG, and CS/Au/BG and counted to be 70.58, and 198.25 µg/mL, respectively (after applied 10 mg/mL). The promising results suggested the use of novel CS/Au/BG nanocomposite as an encourage candidate for wastewater treatment application against pathogenic microbes.

Radiation synthesis and in vitro evaluation of the antimicrobial property of functionalized nanopolymer-based poly (propargyl alcohol) against multidrug-resistance microbes

Pathogenic microorganisms are responsible for many diseases in biological organisms, including humans. Many of these infections thrive in hospitals, where people are treated with medicines and certain bacteria resist those treatments. Consequently, this research article aims to develop efficient antimicrobial material-based conjugated and functionalized polypropargyl alcohol nanoparticles (nano-PGA) synthesized by gamma irradiation. The monomer of PGA was polymerized in various mediums (water (W), chloroform (Ch), and dimethylformamide (DMF)) without catalysts under the action of γ-rays, producing π-conjugated and colored functional nano-PGA polymers. Nano-PGA is a versatile polymer demonstrated here as suitable for creating next-generation of antimicrobial systems capable of effectively preventing and killing various pathogenic microorganisms. The novelty here is the development of polymeric nanostructures by changing the solvent and irradiation doses. The antimicrobial property of nano-PGA (nanostare-like antibody structure) was examined against different pathogenic bacteria and unicellular fungi. Nano-PGA-DMF exhibits significant antimicrobial potential against Staphylococcus aureus (S. aureus) (20.20 mm; zone of inhibition (ZOI), and 0.47 μg/mL; minimum inhibitory concentration (MIC), followed by Escherichia coli (E. coli) (14.50 mm; ZOI, and 1.87 μg/mL; MIC, and Candida albicans (C.albicans) (12.50 mm; ZOI, and 1.87 μg/mL; MIC). In antibiofilm results, the highest inhibition percentage of the synthesized nano-PGA-W, nano-PGA-Ch, and nano-PGA-DMF was documented for S. aureus (17.01%, 37.57%, and 80.27%), followed by E. coli (25.68%, 55.16% and 78.11%), and C.albicans (40.10%, 62.65%, and 76.19%), respectively. The amount of bacterial protein removed is directly proportional after increasing the concentration of nano-PGA-W, nano-PGA-Ch, and nano-PGA-DMF samples (at different concentrations) and counted to be 70.58, 102.89, and 200.87 μg/mL, respectively following the treatment with 1.0 mg/mL of each sample. It was found that the nano-PGA polymer prepared in DMF has better antimicrobial activity than one prepared in chloroform than in water.

Evaluating the Phenotypic and Genomic Characterization of Some Egyptian Phages Infecting Shiga Toxin-Producing Escherichia coli O157:H7 for the Prospective Application in Food Bio-Preservation

Simple Summary

Shiga toxin-producing Escherichia coli (STEC) represents a hazardous health problem because it causes various human gastrointestinal tract diseases, for example, bloody diarrhea and hemorrhagic colitis. The major concern of STEC O157:H7 resulted from its biological characteristics, including low infective dose, ability to express different virulence factors and multidrug resistance of some species. Principally, the human outbreaks of STEC O157:H7 are associated with consumption of undercooked or contaminated bovine dairy and meat products. Treatments of E. coli infections have been increasingly complicated as a result of the development of antibiotic resistance. For this reason, as well as the increasing consumer demand for safe food products, it has become important to apply alternative effective and eco-friendly approaches, such as using lytic phages, to control the growth of pathogenic bacteria in food. This study focused on evaluating the applicability of locally isolated lytic phages specific to Shiga toxin-producing Escherichia coli O157:H7 as prospective biocontrol agents in food. Our findings presented two phages with promising biological and genomic characteristics to be applied in food bio-preservation.

Abstract

Shiga toxin-producing E. coli (STEC) is considered a worldwide public health and food safety problem. Despite the implementation of various different approaches to control food safety, outbreaks persist. The aim of study is to evaluate the applicability of phages, isolated against STEC O157:H7, as prospective food bio-preservatives. Considering the relatively wide host range and greatest protein diversity, two phages (STEC P2 and P4) from four were furtherly characterized. Complete genome analysis confirmed the absence of toxins and virulence factors—encoding genes. The results confirmed the close relation of STEC P2 to phages of Myoviridae, and STEC P4 to the Podoviridae family. The phages retained higher lytic competence of 90.4 and 92.68% for STEC P2 and P4, respectively with the HTST pasteurization. The strong acidic (pH 1) and alkaline (pH 13) conditions had influential effect on the surviving counts of the two phages. The lowest survivability of 63.37 and 86.36% in STEC P2 and P4 lysate, respectively appeared in 2% bile salt solution after 3 h. The results confirmed the strong effect of simulated gastric fluid (SGF) on the survivability of the two phages comparing with simulated intestinal fluid (SIF). Therefore, the two phages could be applied as a natural alternative for food preservation.

Antibiotic Resistance and Biofilm-Forming Ability in Enterococcal Isolates from Red Meat and Poultry Preparations

This study investigated the resistance to antibiotics and the capacity to form a biofilm of 200 isolates of enterococci isolated from raw preparations of beef (51 strains), pork (47), chicken (50), and turkey (52) acquired in north-western Spain. Fifteen antimicrobials of clinical importance were tested by the disc diffusion method. The average number of resistances per strain was 4.48 ± 1.59. If resistant strains were taken together with those showing reduced susceptibility, the total number of resistances per strain was 6.97 ± 2.02. Two isolates (1.0% of strains) were resistant to a single antibiotic, twenty-two isolates (11.0%) presented resistance to two, one strain (0.5%) was resistant to three, and 175 isolates (87.5%) showed a multiple drug-resistant phenotype (MDR; defined as no susceptibility to at least one agent from each of three or more antimicrobial categories). The prevalence of resistance varied between 0.5% (gentamicin) and 100% (kanamycin). All strains produced biofilm on polystyrene microwell plates, determined using crystal violet assay. Isolates were classified as having a weak (51 strains; average optical density at 580 nanometers -OD₅₈₀- = 0.206 ± 0.033), moderate (78 strains; average OD₅₈₀ = 0.374 ± 0.068), or strong (71 strains; average OD₅₈₀ = 1.167 ± 0.621) ability to produce biofilm (p < 0.05). Isolates from beef preparations produced the most substantial (p < 0.05) biofilms. The results of this study indicate that meat and poultry preparations are major reservoirs of antibiotic-resistant enterococcal strains capable of forming a biofilm. In order for food-borne infections to be prevented, the importance of careful handling of these foodstuffs during preparation, avoiding cross-contamination, and ensuring thorough cooking, is stressed.

Diversity, Antibiotic Resistance, and Biofilm-Forming Ability of Enterobacteria Isolated from Red Meat and Poultry Preparations

A total of 44 samples of beef, pork, and poultry preparations were tested. Average counts (log cfu/g) of enterobacteria were 1.99 ± 0.99 (beef preparations), 1.96 ± 1.44 (pork), 2.09 ± 0.92 (chicken), and 2.17 ± 1.06 (turkey) (p > 0.05). Two hundred enterobacterial strains were identified and 13 genera (21 species) were distinguished, including species that are a significant cause of infection. The most common genera were Escherichia (32.5% of strains), Serratia (17.0%), Hafnia (12.5%), and Salmonella (12.0%). Isolates were screened by disc diffusion for susceptibility to 15 antibiotics. A total of 126 strains (63% of the isolates) were multirresistant (having resistance to two or more antibiotics), 46 (23%) were resistant to one antibiotic, and 28 (14%) were sensitive to all antibiotics. The average number of resistances per strain was 2.53 ± 2.05. A higher (p < 0.05) average number of resistances was observed in strains from turkey (3.14 ± 2.55) than in strains from beef (2.15 ± 1.22), pork (2.16 ± 1.39), or chicken (2.44 ± 2.22). At least 50% of strains showed resistance or reduced susceptibility to ampicillin, cefotaxime, ceftazidime, or streptomycin, considered to be "critically important" antimicrobial agents in human medicine. Seventy-nine strains (39.5%), 60 strains (30.0%), and 46 strains (23.0%) were weak, moderate, and strong biofilm producers (crystal violet assay), respectively. This investigation provides evidence that bacteria from red meat and poultry preparations pose major potential risk to consumers.

A Review of Antimicrobial Resistance in Poultry Farming within Low-Resource Settings

The emergence, spread, and persistence of antimicrobial resistance (AMR) remain a pressing global health issue. Animal husbandry, in particular poultry, makes up a substantial portion of the global antimicrobial use. Despite the growing body of research evaluating the AMR within industrial farming systems, there is a gap in understanding the emergence of bacterial resistance originating from poultry within resource-limited environments. As countries continue to transition from low- to middle income countries (LMICs), there will be an increased demand for quality sources of animal protein. Further promotion of intensive poultry farming could address issues of food security, but it may also increase risks of AMR exposure to poultry, other domestic animals, wildlife, and human populations. Given that intensively raised poultry can function as animal reservoirs for AMR, surveillance is needed to evaluate the impacts on humans, other animals, and the environment. Here, we provide a comprehensive review of poultry production within low-resource settings in order to inform future small-scale poultry farming development. Future research is needed in order to understand the full extent of the epidemiology and ecology of AMR in poultry within low-resource settings.

Microbial load and antibiotic resistance in raw beef preparations from northwest Spain

Beef preparations (meatballs, minced meat, hamburgers, white sausages, and red sausages) from northwest Spain were tested. Microbial counts ranged from 0.70 ± 0.00 log10 cfu/g (enterococci) to 9.57 ± 0.37 log10 cfu/g (psychrotrophs). In 73.3% of cases, total aerobic counts were higher than the microbiological limits set for the end of the manufacturing process in the European Union (EU Regulation 2073/2005). Forty Escherichia coli isolates were tested against thirteen clinically important antibiotics (disk diffusion method; CLSI). Three of the strains (7.5%) were susceptible to all the antibiotics, four (10.0%) showed resistance or reduced susceptibility to one antibiotic, and 33 (82.5%) were multiresistant (with resistance or reduced susceptibility to between two and eight antibiotics), with an average of 1.85 resistances per strain. The highest rates of resistance were observed for two antimicrobials widely used on cattle farms (cefalotin and tetracycline). The findings in this research emphasize the need to correctly handle beef preparations with the aim of reducing risks to consumers.

Phylogenetic Diversity, Antimicrobial Susceptibility and Virulence Characteristics of Escherichia coli Isolates from Pigeon Meat

Monitoring resistance to antibiotics in wild animals may assist in evaluating tendencies in the evolution of this major public health problem. The aims of this research work were to determine the patterns of antibiotic resistance in Escherichia coli isolates from the meat of wild or domestically reared pigeons from Spain, to detect the presence of virulence and antibiotic resistance genes, and to carry out a phylogenetic classification of the isolates. Of the 37 E. coli strains tested, 32.43% of them belonged to the B2 phylogenetic group, which is often implicated in extra-intestinal infections. None of the strains showed extended-spectrum beta-lactamase activity. All the isolates presented resistance or reduced susceptibility to two or more antibiotics, with high levels of resistance to β-lactams, aminoglycosides and tetracycline. Ten resistance genes were detected, the most frequent of which were ampC, conferring resistance to ampicillin and aadA, conferring resistance to streptomycin. In total, 97.30% of the strains carried virulence factors (between one and five). The strains from pigeons reared in captivity harboured higher average numbers of resistance and virulence genes than isolates from wild pigeons. Pigeon meat is an important reservoir of E. coli with genes for antibiotic resistance and virulence having the potential to cause disease in humans.

Microbial Load and Antibiotic Resistance Patterns of Escherichia coli and Enterococcus faecalis Isolates from the Meat of Wild and Domestic Pigeons

An expansion in the consumption of pigeon meat has occurred in recent years. However, little is known about microbial load and antibiotic resistance of this foodstuff. The hygiene status and the antibiotic resistance patterns (disc diffusion; Clinical and Laboratory Standards Institute, CLSI) of Escherichia coli and Enterococcus faecalis isolates from wild and domestic pigeon carcasses were investigated. Average microbial loads (log10 cfu/cm2) ranged from 1.40 ± 1.17 (fecal coliforms) to 3.68 ± 1.40 (psychrotrophs). The highest (p < 0.05) microbial loads were observed in domestic pigeons. No substantial differences were found between isolates from domestic and wild pigeons with regard to the prevalence of antibiotic resistance. Of the E. coli strains, 20.00% were susceptible, 25.00% showed resistance or reduced susceptibility to one antimicrobial and 55.00% were multi-resistant. Among the E. faecalis isolates, 2.22% were susceptible and 97.78% were multi-resistant. The greatest prevalence of resistance or reduced susceptibility among E. coli was observed for amoxicillin-clavulanic acid (20.00% strains), ampicillin (26.67%), streptomycin (55.00%) and tobramycin (20.00%). The prevalence of resistance or reduced susceptibility among E. faecalis ranged from 31.11% (trimethoprim/sulfamethoxazole) to 97.78% (erythromycin). Meat from pigeons is a major reservoir of antibiotic-resistant bacteria. The need for the correct handling of this foodstuff in order to reduce risks to consumers is underlined.

Comparison of different approaches to antibiotic restriction in food-producing animals: stratified results from a systematic review and meta-analysis

BACKGROUND

We have previously reported, in a systematic review of 181 studies, that restriction of antibiotic use in food-producing animals is associated with a reduction in antibiotic-resistant bacterial isolates. While informative, that report did not concretely specify whether different types of restriction are associated with differential effectiveness in reducing resistance. We undertook a sub-analysis of the systematic review to address this question.

METHODS

We created a classification scheme of different approaches to antibiotic restriction: (1) complete restriction; (2) single antibiotic-class restriction; (3) single antibiotic restriction; (4) all non-therapeutic use restriction; (5) growth promoter and prophylaxis restriction; (6) growth promoter restriction and (7) other/undetermined. All studies in the original systematic review that were amenable to meta-analysis were included into this substudy and coded by intervention type. Meta-analyses were conducted using random effects models, stratified by intervention type.

RESULTS

A total of 127 studies were included. The most frequently studied intervention type was complete restriction (n=51), followed by restriction of non-therapeutic (n=33) and growth promoter (n=19) indications. None examined growth promoter and prophylaxis restrictions together. Three and seven studies examined single antibiotic-class and single antibiotic restrictions, respectively; these two intervention types were not significantly associated with reductions in antibiotic resistance. Though complete restrictions were associated with a 15% reduction in antibiotic resistance, less prohibitive approaches also demonstrated reduction in antibiotic resistance of 9%-30%.

CONCLUSION

Broad interventions that restrict global antibiotic use appear to be more effective in reducing antibiotic resistance compared with restrictions that narrowly target one specific antibiotic or antibiotic class. Importantly, interventions that allow for therapeutic antibiotic use appear similarly effective compared with those that restrict all uses of antibiotics, suggesting that complete bans are not necessary. These findings directly inform the creation of specific policies to restrict antibiotic use in food-producing animals.

Occurrence of genes encoding aminoglycoside-modifying enzymes in Escherichia coli isolates from chicken meat

1. The aim of the experiment was to determine the occurrence of genes encoding aminoglycoside-modifying enzymes (AMEs) in Escherichia coli isolates recovered from chicken meat.2. Antibiotic sensitivity was tested using the disc diffusion test. AMEs and virulence profile were determined by PCR/sequencing.3. Out of 195 meat samples collected, 185 (95%) isolates were identified as E. coli. Disc diffusion showed a resistance value of 22% (n = 42) for at least one of the antibiotic aminoglycosides (AGs) tested (tobramycin, gentamycin, amikacin and kanamycin). PCR screening showed the presence of three classes of AMEs, namely, aac(3)-II (12%), aac(6')-Ib (7%) and aac(2')-Ia (5%). Eight of the 42 isolates were positive for the stx₁ and sxt₂ genes and were defined as Shiga toxin-producing E coli., while the eae gene was positive in one strain. Among the 42 isolates, group A was the predominant phylogenetic identified (76%), followed by group D (21%). One isolate belonged to subgroup B2₃.4. The results suggested that chicken meat could be an important reservoir of AMEs, and pose a potential risk by dissemination of resistance to humans through the food chain.

Diverse Mobile Genetic Elements and Conjugal Transferability of Sulfonamide Resistance Genes (sul1, sul2, and sul3) in Escherichia coli Isolates From Penaeus vannamei and Pork From Large Markets in Zhejiang, China

High prevalence rates of sulfonamide resistance genes sul1, sul2, and sul3 have been observed in Gram-negative bacteria isolated from humans, domestic animals, and aquaculture species worldwide. We investigated the distribution characteristics, location, conjugative transferability, and genetic environments of sul genes from Escherichia coli isolates collected from Penaeus vannamei and pork samples from three large markets in Zhejiang, China. The prevalence rates of sul genes in sulfonamide-resistant E. coli isolates from P. vannamei and pork samples were 90.0 and 88.6%, respectively, and the prevalence of sul1 and sul2 was significantly higher than that of sul3 (p < 0.05). Twenty-four representative sul-positive E. coli isolates were analyzed in detail. Southern blot hybridization confirmed that sul genes of E. coli isolates were located on plasmids and/or chromosomes. Transfer of resistance through conjugation was observed in all 18 E. coli isolates harboring sul genes on plasmids. Replicon typing identified seven different incompatibility groups and IncF was the dominant replicon type among sul gene-containing plasmids from both sources. PCR walking analysis indicated that 87.5% (35/40) of sul gene-related fragments carried insertion sequences (ISs) belonging to a variety of families in diverse sites, with IS26 occurring most frequently. In addition, the sul1 gene was detected mainly in fragments carrying class 1 integrons. Co-location on the same fragment with resistance genes that may contribute to the persistence and dissemination of sul1 and/or sul2 genes. The diversity of mobile genetic elements and resistance genes adjacent to sul3 was much lower than those adjacent to sul1 and sul2, especially those located in chromosomes, which reduced the transmission potential of the sul3 gene. In conclusion, combined with the results of clonal relatedness analysis by PFGE and MLST of 24 representative E. coli isolates from P. vannamei and pork samples, it showed that a small number of sul genes were vertically transmitted among E. coli from P. vannamei and that horizontal gene transfer was likely the main transmission mechanism of sul genes from both sources. Our results provide important information to better understand the risk of transmission of sul genes from seafood and meat to humans.

Examination of unintended consequences of antibiotic use restrictions in food-producing animals: Sub-analysis of a systematic review

Antimicrobial resistance is considered one of the greatest threats to global and public health today. The World Health Organization, the Food and Agriculture Organization, and the World Organisation for Animal Health, known as the Tripartite Collaboration, have called for urgent action. We have previously published a systematic review of 181 studies, demonstrating that interventions that restrict antibiotic use in food-producing animals are associated with a reduction in antibiotic resistant bacterial isolates in both animals and humans. What remains unknown, however, are whether (and what) unintended consequences may arise from such interventions. We therefore undertook a sub-analysis of the original review to address this research question. A total of 47 studies described potential consequences of antibiotic restrictions. There were no consistent trends to suggest clear harm. There may be increased bacterial contamination of food products, the clinical significance of which remains unclear. There is a need for rigorous evaluation of the unintended consequences of antibiotic restrictions in human health, food availability, and economics, given their possible widespread implications.

Extra-Intestinal Fluoroquinolone-Resistant Escherichia coli Strains Isolated from Meat

Extra-intestinal E. coli are emerging as a global threat due to their diffusion as opportunistic pathogens and, above all, to their wide set of antibiotic resistance determinants. There are still many gaps in our knowledge of their origin and spread pathways, although food animals have been adjudicated vehicles for passing mult-drug resistant bacteria to humans. This study analyzed 46 samples of meat purchased from retail stores in Palermo in order to obtain quinolone-resistant E. coli isolates. Strains were screened for their phylogenetic groups, ST131-associated single nucleotide polymorphisms (SNPs), and then typed by ERIC-PCR. Their set of virulence factors, namely, kpsMII, papA, sfaS, focG, iutA, papC, hlyD, and afa genes, were investigated and their fluoroquinolone-resistance determinants evaluated. The data obtained show a dramatically high prevalence of multidrug resistance patterns in the Palermo area, with 28% of the isolates having virulence factor genes typical of ExPEC strains. No B2 group or ST131 strains were detected. Moreover, 20% of our isolates showed positivity to all the plasmid-mediated quinolone resistance (PMQR) determinants, showing a potential to transfer these genes among other bacteria. Therefore, these data underline the possibility that food animals and, specifically, poultry in particular may be a significant source of resistant bacterial strains, posing a potential zoonotic risk.

Antibiotic susceptibility of methicillin-resistant staphylococci (MRS) of food origin: A comparison of agar disc diffusion method and a commercially available miniaturized test

Methicillin-resistant staphylococci (MRS) are a major concern to public and animal health. Thirty MRS (Staphylococcus aureus, S. cohnii, S. epidermidis, S. haemolyticus, S. hominis, S. lentus, S. lugdunensis, S. sciuri, and S. xylosus) isolates from meat and poultry preparations were tested for antimicrobial susceptibility to 11 antimicrobials (belonging to seven different categories) of clinical significance using both the standard agar disc diffusion method and a commercially available miniaturized system (Sensi Test Gram-positive). It is worth stressing that 16 isolates (53.33%) exhibited an extensively drug-resistant phenotype (XDR). The average number of resistances per strain was 4.67. These results suggest that retail meat and poultry preparations are a likely vehicle for the transmission of multi-drug resistant MRS. Resistance to erythromycin was the commonest finding (76.67% of strains), followed by tobramycin, ceftazidime (66.67%), ciprofloxacin (56.67%) and fosfomycin (53.33%). An agreement (kappa coefficient) of 0.64 was found between the two testing methods. Using the agar disc diffusion as the reference method, the sensitivity, specificity and accuracy of the miniaturized test were 98.44%, 69.44% and 83.33%, respectively. Most discrepancies between the two methods were due to isolates that were susceptible according to the disc diffusion method but resistant according to the miniaturized test (false positives).

Occurrence of virulent and antibiotic-resistant Shiga toxin-producing Escherichia coli in some food products and human stool in Egypt

AIM

Shiga toxin-producing Escherichia coli (STEC) represent a severe public health issue worldwide, causing life-threatening diseases in the human gastrointestinal tract. This study aimed to determine the occurrence of virulent and antibiotic-resistant STEC in retail meat and milk products and human stool samples and to characterize the genes encoding for virulence and antibiotic resistance among the identified STEC isolates.

MATERIALS AND METHODS

A total of 260 food samples were randomly collected from retail markets in different localities of El Giza Governorate, Egypt. 50 stool specimens were obtained from children that had diarrhea at Embaba Fever Hospital. All collected samples were initially subjected to bacteriological examination and serotyping, and then subsequently, the isolates were exposed to polymerase chain reaction application and sequencing for the identification of the virulence-related genes. Finally, the virulent STEC isolates were tested for antibiotic susceptibility.

RESULTS

Serotyping of the 76 biochemically identified isolates showed that 18 were STEC with a predominance of non-O157 (16) while 2 O157:K-serotype was detected only in one food and one human isolate. Molecular identification of the virulence genes illustrated that the minced meat showed the highest prevalence of STEC (8%) as compared to the other food products. In the humans, the O157 was the only serotype that expresses the Shiga toxin-associated gene (eaeA). Antibiotic susceptibility test displayed that 13 of the 17 food and human isolates (76.47%) were resistant to cephalothin (KF30). 9 of the 13 cephalothin-resistant isolates harbor the β lactamase (blaTEM )-resistant gene. All isolates were sensitive to chloramphenicol, ciprofloxacin, amikacin, and gentamicin. DNA sequencing and phylogenetic analysis of the stx2-positive minced meat isolate revealed a high genetic relatedness with beef minced meat from the USA and Australia.

CONCLUSION

This study showed the predominance of non-O157 among the identified isolates. Minced meat showed the highest prevalence of STEC as compared to the other food products, and this work illustrates the necessity to consider the food products as a potential source of the non-O157 STEC serotypes. DNA sequencing and phylogenetic analysis revealed a high genetic relatedness with beef minced meat from the USA and Australia. This highlights the high probability of worldwide spread of such serotypes, signifying the importance of the one world concept.

Antibiotic resistance, virulence factors and biofilm formation ability in Escherichia coli strains isolated from chicken meat and wildlife in the Czech Republic

Attachment of pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent a serious threat for the food industry, since these bacteria are more resistant to antimicrobials or possess more virulence factors. The main aim of this study was to investigate the correlation between antibiotic resistance against 13 antibiotics, distribution of 10 virulence factors and biofilm formation in 105 Escherichia coli strains according to their origin. The high prevalence of antibiotic resistance that we have found in wildlife isolates could be acquired by horizontal transfer of resistance genes from human or domestic or farm animals. Consequently, these commensal bacteria might serve as indicator of antimicrobial usage for human and veterinary purposes in the Czech Republic. Further, 46 out of 66 resistant isolates (70%) were able to form biofilm and we found out statistically significant correlation between prevalence of antibiotic resistance and biofilm formation ability. The highest prevalence of antibiotic resistance was observed in weak biofilm producers. Biofilm formation was not statistically associated with any virulence determinant. However, we confirmed the correlation between prevalence of virulence factors and host origin. Chicken isolates possessed more virulence factors (66%), than isolates from wildlife (37%). We can conclude that the potential spread of antibiotic resistance pattern via the food chain is of high concern for public health. Even more, alarming is that E. coli isolates remain pathogenic potential with ability to form biofilm and these bacteria may persist during food processing and consequently lead to greater risks of food contamination.

Prevalence of Antibiotic-Resistant Fecal Escherichia coli Isolates from Penned Broiler and Scavenging Local Chickens in Arusha, Tanzania

We compared the prevalence of antibiotic-resistant Escherichia coli isolates from household-level producers of broiler (commercial source breeds) and local chickens in the Arusha District of Tanzania. Households were composed of a single dwelling or residence with independent, penned broiler flocks. Free-range, scavenging chickens were mixed breed and loosely associated with individual households. A total of 1,800 E. coli isolates (1,200 from broiler and 600 from scavenging local chickens) from 75 chickens were tested for their susceptibility against 11 antibiotics by using breakpoint assays. Isolates from broiler chickens harbored a higher prevalence of antibiotic-resistant E. coli relative to scavenging local chickens, including sulfamethoxazole (80.3 versus 34%), followed by trimethoprim (69.3 versus 27.7%), tetracycline (56.8 versus 20%), streptomycin (52.7 versus 24.7%), amoxicillin (49.6 versus 17%), ampicillin (49.1 versus 16.8%), ciprofloxacin (21.9 versus 1.7%), and chloramphenicol (1.5 versus 1.2%). Except for resistance to chloramphenicol, scavenging local chickens harbored fewer resistant E. coli isolates (P < 0.05). Broiler chickens harbored more isolates that were resistant to ≥7 antibiotics (P < 0.05). The higher prevalence of antibiotic-resistant E. coli from broiler chickens correlated with the reported therapeutic and prophylactic use of antibiotics in this poultry population. We suggest that improved biosecurity measures and increased vaccination efforts would reduce reliance on antibiotics by these households.

Antimicrobial activity and mechanisms of Salvia sclarea essential oil

BACKGROUND

Nowadays, essential oils are recognized as safe substances and can be used as antibacterial additives. Salvia sclarea is one of the most important aromatic plants cultivated world-wide as a source of essential oils. In addition to being flavoring foods, Salvia sclarea essential oil can also act as antimicrobials and preservatives against food spoilage. Understanding more about the antibacterial performance and possible mechanism of Salvia sclarea essential oil will be helpful for its application in the future. But so far few related researches have been reported.

RESULTS

In our study, Salvia sclarea oil showed obvious antibacterial activity against all tested bacterial strains. Minimum inhibitory concentration (MIC) and minimum bactericide concentration (MBC) of seven pathogens were 0.05 and 0.1 % respectively. In addition, Salvia sclarea oil also exhibited a significant inhibitory effect on the growth of Escherichia coli (E. coli) in phosphate buffer saline (PBS) and meats. After treated with Salvia sclarea oil, Scanning Electron Microscope (SEM) images can clearly see the damage of cell membrane; the intracellular ATP concentrations of E. coli and S. aureus reduced 98.27 and 69.61 % respectively, compared to the control groups; the nuclear DNA content of E. coli and S. aureus was significantly reduced to 48.32 and 50.77 % respectively. In addition, there was massive leakage of cellular material when E. coli and S. aureus were exposed to Salvia sclarea oil.

CONCLUSIONS

Salvia sclarea essential oil damaged the cell membrane and changed the cell membrane permeability, leading to the release of some cytoplasm such as macromolecular substances, ATP and DNA. In general, the antimicrobial action of Salvia sclarea essential oil is not only attributable to a unique pathway, but also involves a series of events both on the cell surface and within the cytoplasm. Therefore, more experiments need to be done to fully understand the antimicrobial mechanism of Salvia sclarea essential oil.

Resistance and virulence factors of Escherichia coli isolated from chicken

Chicken meat has become an important part of the human diet and besides contamination by pathogenic Escherichia coli there is a risk of antibiotic resistance spreading via the food chain. The purpose of this study was to examine the prevalence of resistance against eight antibiotics and the presence of 14 virulence factors among 75 Escherichia coli strains isolated from chicken meat in the Czech Republic after classification into phylogenetic groups by the multiplex PCR method. More than half of strains belonged to A phylogroup, next frequently represented was B1 phylogroup, which suggests the commensal strains. The other strains were classified into phylogroups B2 and D, which had more virulence factors. Almost half of all E. coli strains were resistant to at least one of eight-tested antibiotics. A multidrug resistance was observed in 13% of strains. The most prevalent virulence genes were iucD, iss and tsh. None of genes encoding toxins was detected. Most of E. coli strains isolated from chicken meat can be considered as nonpathogenic on the basis of analysis of virulence factors, antibiotic resistance and phylogroups assignment. It can provide a useful tool for prediction of a potential risk from food contaminated by E. coli.

Antimicrobial resistance in indicator Escherichia coli isolates from free-ranging livestock and sympatric wild ungulates in a natural environment (Northeastern Spain)

Antimicrobial resistance was assessed in indicator Escherichia coli isolates from free-ranging livestock and sympatric wild boar (Sus scrofa) and Iberian ibex (Capra pyrenaica) in a National Game Reserve in northeastern Spain. The frequency of antimicrobial resistance was low (0% to 7.9%). However, resistance to an extended-spectrum cephalosporin and fluoroquinolones was detected.

Prevalence of antibiotic-resistant E. coli in retail chicken: comparing conventional, organic, kosher, and raised without antibiotics

Retail poultry products are known sources of antibiotic-resistant Escherichia coli, a major human health concern. Consumers have a range of choices for poultry, including conventional, organic, kosher, and raised without antibiotics (RWA) - designations that are perceived to indicate differences in quality and safety. However, whether these categories vary in the frequency of contamination with antibiotic-resistant E. coli is unknown. We examined the occurrence of antibiotic-resistant E. coli on raw chicken marketed as conventional, organic, kosher and RWA. From April - June 2012, we purchased 213 samples of raw chicken from 15 locations in the New York City metropolitan area. We screened E. coli isolates from each sample for resistance to 12 common antibiotics. Although the organic and RWA labels restrict the use of antibiotics, the frequency of antibiotic-resistant E. coli tended to be only slightly lower for RWA, and organic chicken was statistically indistinguishable from conventional products that have no restrictions. Kosher chicken had the highest frequency of antibiotic-resistant E. coli, nearly twice that of conventional products, a result that belies the historical roots of kosher as a means to ensure food safety. These results indicate that production methods influence the frequency of antibiotic-resistant E. coli on poultry products available to consumers. Future research to identify the specific practices that cause the high frequency of antibiotic-resistant E. coli in kosher chicken could promote efforts to reduce consumer exposure to this potential pathogen.

Prevalence of antibiotic-resistant E. coli in retail chicken: comparing conventional, organic, kosher, and raised without antibiotics

Retail poultry products are known sources of antibiotic-resistant Escherichia coli, a major human health concern. Consumers have a range of choices for poultry, including conventional, organic, kosher, and raised without antibiotics (RWA) - designations that are perceived to indicate differences in quality and safety. However, whether these categories vary in the frequency of contamination with antibiotic-resistant E. coli is unknown. We examined the occurrence of antibiotic-resistant E. coli on raw chicken marketed as conventional, organic, kosher and RWA. From April - June 2012, we purchased 213 samples of raw chicken from 15 locations in the New York City metropolitan area. We screened E. coli isolates from each sample for resistance to 12 common antibiotics. Although the organic and RWA labels restrict the use of antibiotics, the frequency of antibiotic-resistant E. coli tended to be only slightly lower for RWA, and organic chicken was statistically indistinguishable from conventional products that have no restrictions. Kosher chicken had the highest frequency of antibiotic-resistant E. coli, nearly twice that of conventional products, a result that belies the historical roots of kosher as a means to ensure food safety. These results indicate that production methods influence the frequency of antibiotic-resistant E. coli on poultry products available to consumers. Future research to identify the specific practices that cause the high frequency of antibiotic-resistant E. coli in kosher chicken could promote efforts to reduce consumer exposure to this potential pathogen.

Decontamination treatments can increase the prevalence of resistance to antibiotics of Escherichia coli naturally present on poultry

The main objective of this study was to determine the ability of various decontaminants to increase the prevalence of resistance to antibiotics in Escherichia coli populations on poultry. Chicken legs were dipped for 15 min into aqueous solutions (wt/vol) of trisodium phosphate (TSP; 12%), acidified sodium chlorite (ASC; 1200 ppm), ascorbic acid (AA; 2%) or citric acid (CA; 2%), or tap water (control). Samples were analyzed immediately after treatment (day 0) and after five days of storage at 7 ± 1 °C. A total of 250 E. coli isolates (50 from each group of samples; 25 on day 0 and 25 on day 5) were tested against twelve antibiotics of clinical significance by means of a standard disc-diffusion technique. A high prevalence of resistance to antibiotics was observed for E. coli strains from control samples, with three (6.0%) isolates sensitive, three (6.0%) resistant to one antibiotic and 44 (88.0%) isolates resistant to two or more antibiotics. Isolates from control samples had a lower prevalence of resistance than those from treated samples to ampicillin-sulbactam (P < 0.01, samples treated with TSP), amoxicillin-clavulanic acid (P < 0.001, ASC, AA and CA), cephotaxime (P < 0.05, TSP), trimethoprim-sulphamethoxazole (P < 0.05, AA; P < 0.01, CA), tetracycline (P < 0.01, CA), ciprofloxacin (P < 0.001, ASC; P < 0.05, AA; P < 0.01, CA) and nitrofurantoin (P < 0.01, TSP). These results suggest that the chemical decontaminants tested could favor the emergence, selection and/or proliferation of antibiotic-resistant strains in microbial populations on poultry meat.