Antibiotic susceptibility pattern of Escherichia coli strains with verocytotoxic E. coli-associated virulence factors from food and animal faeces

The Wide Range of Antibiotic Resistance and Variability of Genotypic Profiles in Escherichia coli from Domestic Animals in Eastern Sicily

The emergence of multidrug resistance among Enterobacteriaceae in livestock poses a serious public health threat. Escherichia coli, a usual host of intestinal microbiota, is recognized also as etiological agent of numerous infections widespread in both humans and animals. The colibacillosis is one of the most reported zoonoses worldwide, typically treated with antibiotics in the primary stages. This strategy has promoted the onset of antibiotic-resistant serotypes of E. coli, reducing the effectiveness of therapeutic treatments and contributing to antibiotic resistance spread. The current study focused on biodiversity, pathogenicity, and antibiotic resistance profile of 104 E. coli strains isolated from domestic animals in Eastern Sicily. The strains were isolated from sick animals and carcasses of six different animal species and screened for resistance against 16 antibiotic molecules, as recommended by WHO and OIE. The antibiotic resistance patterns highlighted that all strains were multi-resistant, showing resistance to at least three antibiotic classes. The highest incidence of resistance was observed against amoxicillin (100%), tylosin (97%), sulfamethoxazole (98%), and erythromycin (92%), while the lowest for colistin (8%). The pathotype characterization identified two EPEC strains and the study of genetic linkage (PFGE) showed a wide variety of profiles. The current study emphasized the wide range of multidrug resistance and genotyping profiles in E. coli isolated in Easter Sicily.

The Quantity and Quality of Illegally Imported Products of Animal Origin in Personal Consignments into the European Union Seized at Two German Airports between 2010 And 2014

The import of products of animal origin (POAO) in travellers’ personal consignments presents a considerable risk of introducing animal diseases and emerging zoonoses into the European Union. The current regulation (EU) 206/2009 implements strict measures for illegally imported POAO, whereupon non-complying products have to be seized and destroyed regardless. Especially airports serve as global bottlenecks for illegally imported POAO where passenger controls of non-European flights are performed by customs and veterinary services in collaboration. Results of these control measures have to be submitted in the form of annual reports to the European Commission. However, few data on qualities and quantities of seizures have been published so far. In this study, POAO seized at two German airports between 2010 and 2014 were analysed in terms of quantities, qualitative categories and region of origin. In most years considered, more than 20 tonnes POAO were seized at each airport. However, reported amounts of seizures seem to be only the tip of the iceberg as an all-passenger control is not feasible and therefore travellers are only spot-checked. The analysis suggests that the organisational structures of both customs and official veterinary services and their different risk perceptions interfere in completing an effective ban on the illegal import of POAO.

The prevalence, distribution and characterization of Shiga toxin-producing Escherichia coli (STEC) serotypes and virulotypes from a cluster of bovine farms

AIMS

To assess the prevalence of Shiga toxin-producing Escherichia coli (STEC) on a cluster of twelve beef farms in the north-east of Ireland.

METHODS AND RESULTS

Samples were screened for stx1 and stx2 using PCR. Positive samples were enriched in mTSB and STEC O157 isolated using immunomagnetic separation. Enrichment cultures were plated onto TBX agar to isolate non-O157 STEC. All isolates were serotyped and examined for a range of virulence genes and their antibiotic resistance phenotype determined. Eighty-four isolates of 33 different serotypes were cultured from the 13·7% of samples that were stx positive. The most prevalent serotype was O157:H7, the most common Shiga toxin was stx(2) , and a variety of virulence factor combinations was observed. O-:H-, O26:H11, O76:H34, O157:H7, O157:H16 and OX18:H+ also carried eaeA and hlyA genes. Twenty-nine per cent of strains were resistant to at least one antibiotic, 48% of which had multiple drug resistance (MDR) with O2:H32 displaying resistance to five antibiotics.

CONCLUSIONS

The ubiquitous nature of STEC on beef farms, the detection of stx(+) eaeA(+) hlyA(+) in the serotypes O-:H-, O157:H16 and OX18:H+ in addition to O157:H7 and O26:H11 and the widespread distribution of antibiotic resistance are of public health concern as new virulent STEC strains are emerging.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study found no relationship between serotype and antibiotic resistance, therefore negating efforts to isolate serotypes using specific antibiotic supplemented media. The data presented provide further evidence of the emergence of new STEC virulotypes of potential public health significance.

Antibiotic resistance of Escherichia coli in leachates from municipal solid waste landfills: comparison between semi-aerobic and anaerobic operations

A bacterial susceptibility test to 31 antibiotics was conducted on the 80 isolated Escherichia coli from the leachates of the landfills in two different operations: semi-aerobic (SL) and anaerobic (AL) landfills. The average population of E. coli from SL and AL leachates were 2.2 × 10(4) and 9.4 × 10(3)CFU/100ml, respectively. Between 80.8% and 87.5% of the E. coli isolated from both leachates as resistant to the tested antibiotics and high resistances were found to doxycycline (53.8-68.8%), cephalothin (57.5-61.3%), tetracycline (51.3-67.5%) and minocycline (37.5-46.3%). The percentages of isolates resistant to most antibiotics were higher in the AL leachate. The exception was nitrofurantoin to which the isolates from the SL were highly resistant. E. coli from both sources showed similarly high susceptibilities (90-100%) to aminoglycosides, quinolones, chloramphenicol, sulfonamide and some new beta-lactams. The difference in available oxygen in landfills could affect E. coli susceptibility to antibiotics in leachates.

Antimicrobial resistance of emerging foodborne pathogens: status quo and global trends

Emerging foodborne pathogens are challenging subjects of food microbiology with their antibiotic resistance and their impact on public health. Campylobacter jejuni, Salmonella spp. and Verotoxigenic Escherichia coli (VTEC) are significant emerging food pathogens, globally. The decrease in supply and increase in demand lead developed countries to produce animal products with a higher efficiency. The massive production has caused the increase of the significant foodborne diseases. The strict control of food starting from farm to fork has been held by different regulations. Official measures have been applied to combat these pathogens. In 2005 EU declared that, an EU-wide ban on the use of antibiotics as growth promoters in animal feed would be applied on 1 January 2006. The ban is the final step in the phasing out of antibiotics used for non-medical purposes. It is a part of the Commission's strategy to tackle the emergence of bacteria and other microbes resistant to antibiotics, due to their overexploitation or misuse. As the awareness raises more countries banned application of antibiotics as growth promoter, but the resistance of the emerging foodborne pathogens do not represent decrease. Currently, the main concern of food safety is counter measures against resistant bugs.

Molecular epidemiology of microorganisms isolated from food workers and enteral feeding of public hospitals

This study aimed to compare strains of Staphylococcus aureus and E. coli isolated from food workers and enteral diet samples obtained from 2 public hospitals (H1/H2) in Goiania, Goias, Brazil, by the means of antibiogram and pulsed field gel electrophoresis (PFGE). In the H1, strains of S. aureus were present in 2 enteral diet samples and in 13 food worker swabs. Strains of E. coli were found in an enteral diet sample from H1 and in 2 enteral diet samples from H2 and in 6 food worker swabs in the H1 and in 12 food worker swabs from H2. According to the antibiogram, the 6 susceptibility profiles (A to F) of 15 S. aureus strains colonizing personnel and enteral feeding did not allow the identification of the probable source of diet contamination. All 20 E. coli strains isolated from the H1 and H2 were grouped in 4 phenotypic profiles (A to D). The phenotypes A (H1) and C (H2) showed the same profile for microorganisms isolated from handlers and diets, suggesting more phenotypic similarity among these samples. PFGE genotyping showed that S. aureus isolates from diets were related to a single strain isolated from a food worker suggesting that in this case the reason for the diet contamination may be a result of food handling. The food worker appears to be the most probable source of E. coli contamination for enteral feeding from H2. This fact emphasizes on the food workers as a risk of bacterial transmission for the diets and that the diet chain production must be controlled.

PRACTICAL APPLICATION

The study emphasizes the importance of monitoring the enteral diet microbiological quality and the factors associated to its contamination. The study highlights the use of molecular biology as an instrument to correlate strains to determine the origin of the final product contamination.

Rapid microarray-based genotyping of enterohemorrhagic Escherichia coli serotype O156:H25/H-/Hnt isolates from cattle and clonal relationship analysis

Since enterohemorrhagic Escherichia coli (EHEC) isolates of serogroup O156 have been obtained from human diarrhea patients and asymptomatic carriers, we studied cattle as a potential reservoir for these bacteria. E. coli isolates serotyped by agglutination as O156:H25/H-/Hnt strains (n = 32) were isolated from three cattle farms during a period of 21 months and characterized by rapid microarray-based genotyping. The serotyping by agglutination of the O156 isolates was not confirmed in some cases by the results of DNA-based serotyping as only 25 of the 32 isolates were conclusively identified as O156:H25. In the multilocus sequence typing (MLST) analysis, all EHEC O156:H25 isolates were characterized as sequence type 300 (ST300) and ST688, which differ by a single-nucleotide exchange in the purA gene. Oligonucleotide microarrays allow simultaneous detection of a wider range of EHEC-associated and other E. coli virulence markers than other methods. All O156:H25 isolates showed a wide spectrum of virulence factors typical for EHEC. The stx(1) genes combined with the EHEC hlyA (hlyA(EHEC)) gene, the eae gene of the zeta subtype, as well as numerous other virulence markers were present in all EHEC O156:H25 strains. The behavior of eight different cluster groups, including four that were EHEC O156:H25, was monitored in space and time. Variations in the O156 cluster groups were detected. The results of the cluster analysis suggest that some O156:H25 strains had the genetic potential for a long persistence in the host and on the farm, while other strains did not. As judged by their pattern of virulence markers, E. coli O156:H25 isolates of bovine origin may represent a considerable risk for human infection. Our results showed that the miniaturized E. coli oligonucleotide arrays are an excellent tool for the rapid detection of a large number of virulence markers.

Safety of raw meat and shellfish in Vietnam: an analysis of Escherichia coli isolations for antibiotic resistance and virulence genes

This study was conducted to examine a current baseline profile of antimicrobial resistance and virulence of Escherichia coli isolated from foods commonly sold in the market place in Vietnam. E. coli were isolated from 180 samples of raw meat, poultry and shellfish and also isolated from 43 chicken faeces samples. Ninety-nine E. coli isolates recovered from all sources were selected for the investigation of their susceptibility to 15 antimicrobial agents by the disk diffusion method. Eighty-four percent of the isolates were resistant to one or more antibiotics, and multi-resistance, defined as resistance to at least 3 different classes of antibiotics, was detected in all sources. The rates of multi-resistance were up to 89.5% in chicken, 95% in chicken faeces and 75% in pork isolates. Resistance was most frequently observed to tetracycline (77.8%), sulfafurazole (60.6%), ampicillin (50.5%), amoxicillin (50.5%), trimethoprim (51.5%), chloramphenicol (43.4%), streptomycin (39.4%), nalidixic acid (34.3%) and gentamicin (24.2%). In addition, the isolates also displayed resistance to fluoroquinolones (ciprofloxacin 16.2%, norfloxacin 17.2%, and enrofloxacin 21.2%), with chicken isolates showing the highest rates of resistance to these antibiotics (52.6-63.2%). Thirty-eight multi-resistant isolates were selected for further the examination of antibiotic resistance genes and were also evaluated for virulence gene profiles by multiplex and uniplex polymerase chain reaction. The beta-lactam TEM gene and tetracycline resistance tetA, tetB genes were frequently detected in the tested isolates (84.2% and 89.5% respectively). Genes which are responsible for resistance to streptomycin (aadA) (68.4%), chloramphenicol (cmlA) (42.1%), sulfonamides (sulI) (39.5%), trimethoprim (dhfrV) (26.3%) and kanamycin (aphA-1) (23.7%) were also widely distributed. Plasmid-mediated ampC genes were detected in E. coli isolates from chicken and pork. The isolates were tested for the presence of 58 virulence genes for adhesins, toxins, capsule synthesis, siderophores, invasins and others from different E. coli pathotypes. All of the tested isolates contained at least one virulence gene and there were 16 genes detected. Virulence genes detected were fimH (92.1%), bmaE (84.2%), TSPE4.C2 (42.1%), aidA AIDA-I (orfB) (31.6%), east1 (26.3%), traT (23.7%), and others including fyuA, iutA, chuA, yjaA, iss, iroN(E. coli), ibeA, aah (orfA), iha and papG allele III (10.5-2.6%). Typical toxin genes produced by enterohemorrhagic and enterotoxigenic E. coli pathotypes (a heat-stable toxin (ST), heat-labile toxin (LT) and Shiga toxin stx1, stx2) were not detected in any of these 38 isolates. The study has revealed that E. coli in raw foods is a significant reservoir of resistance and virulence genes.

The non-O157 shiga-toxigenic (verocytotoxigenic) Escherichia coli; under-rated pathogens

Following a brief review of the ecology of Escherichia coli in general, the role of Shiga-Toxigenic (Verocytotoxigenic) E. coli (STEC) as pathogens is addressed. While STEC belonging to the serogroup O157 have been extensively studied and shown to be involved in many cases and outbreaks of human disease, the importance of STEC belonging to other serogroups has not been recognized as much. This review addresses the problems associated with these pathogens, demonstrating that increasing the awareness of them is a major part of the problem. This review then demonstrates how widespread isolations especially from food animals and human disease have been, discussing in particular STEC belonging to serogroups O8, O26, O103, O111, O113 and O128. The animal host-specificity of these STEC is also reviewed. In conclusion some methods of improving isolation of these pathogens is addressed.

Medicinal plant extracts as anti-Escherichia coli O157:H7 agents and their effects on bacterial cell aggregation

Ethanolic extracts of eight Thai medicinal plants (representing five families) that are used as traditional remedies for treating diarrhea were examined with a salt aggregation test for their ability to modulate cell surface hydrophobicity of enterohemorrhagic Escherichia coli strains, including E. coli O157:H7. Four of these medicinal plants, Acacia catechu, Peltophorum pterocarpum, Punica granatum, and Quercus infectoria, have high bacteriostatic and bactericidal activities. The ethanolic extract of Q. infectoria was the most effective against all strains of E. coli, with MICs of 0.12 to 0.98 mg/ml and MBCs of 0.98 to 3.91 mg/ml. The ethanolic extract of P. granatum had MICs of 0.49 to 1.95 mg/ml and MBCs of 1.95 to 3.91 mg/ml. Ethanolic extracts of Q. infectoria, P. pterocarpum, and P. granatum were among the most effective extracts against the two strains of E. coli O157:H7. The other four plants, Andrographis paniculata, Pluchia indica, Tamarindus indica, and Walsura robusta, did not have high bacteriostatic and bactericidal activities but were able to affect hydrophobicity characteristics on their outermost surface. All plants except Q. infectoria had some ability to increase cell surface hydrophobicity. There appears to be no correlation between antibacterial activity and cell aggregative properties.

Preliminary study of certain serotypes, genetic and antimicrobial resistance profiles of verotoxigenic Escherichia coli (VTEC) isolated in Bosnia and Germany from cattle or pigs and their products

The aim of this study was to gather more information on the spread of VTEC serotypes, genetic profiles and resistance patterns from pigs or pork and from cattle or beef in different areas, and to improve detection of the source of outbreaks with a wider data pool. Of 130 Escherichia coli samples isolated from a cattle slaughter house and beef retail products in Sarajevo, Bosnia and Herzegovina (BiH), seven were identified as verotoxigenic (VTEC). In comparison, 22 VTEC of 264 E. coli isolates were isolated from bovine faeces (14) and beef products (8) from Germany. Furthermore 23 VTEC of 76 isolates were identified from pig carcasses (10), faeces (9) and pork products (4) from Germany. Gene detection and serotyping were carried out in our laboratory and in the National Reference Laboratory. Antimicrobial resistance was tested with the dilution method in microtitre plates. All porcine isolates belonged to serotypes thus far not associated with human disease. Bovine VTEC were either serotypes commonly associated with human diseases (O157:H7, O103:H2, O157:H-) or rare serotypes. One serotype (O96:H19) was found only in isolates from Sarajevo. Most German VTEC, especially those of porcine origin, had only vtx2 genes, whereas all Bosnian isolates had vtx1 and vtx2 genes. The eae gene was found only in "classical" VTEC serotypes. All 52 VTEC (100%) investigated were resistant to the three sulfonamides tested; porcine isolates were mainly resistant to oxytetracycline (43%) and chlortetracycline (37%), bovine isolates mainly to trimethoprim/sulfamethoxazole and ampicillin (10% each). If sulfonamide resistances are disregarded, more than half (53.8%) of porcine VTEC were multiresistant and one-fourth (25%) of German bovine isolates, but none of the Bosnian bovine isolates. The results show the considerable spread of resistances in VTEC. These results also point out the necessity of gathering data from different geographical areas in order to be able to identify typical local variations in serotypes or gene expression and thus to trace human infections more quickly to their source.

Antimicrobial resistance and genetic profiling of Escherichia coli from a commercial beef packing plant

The objective of this study was to investigate the extent of antimicrobial resistance and to genetically characterize resistant Escherichia coli recovered from a commercial beef packing plant. E. coli isolates were recovered by a hydrophobic grid membrane filtration method by direct plating on SD-39 medium. A total of 284 isolates comprising 71, 36, 55, 52, and 70 isolates from animal hides, washed carcasses, conveyers, beef trimmings, and ground beef, respectively, were analyzed. The susceptibility of E. coli isolates to 15 antimicrobial agents was evaluated with an automated broth microdilution system, and the genetic characterization of these isolates was performed by the random amplified polymorphic DNA (RAPD) method. Of the 284 E. coli isolates, 56% were sensitive to all 15 antimicrobial agents. Resistance to tetracycline, ampicillin, and streptomycin was observed in 38, 9, and 6% of the isolates, respectively. Resistance to one or more antimicrobial agents was observed in 51% of the E. coli isolates recovered from the hides but in only 25% of the E. coli from the washed carcasses. Resistance to one or more antimicrobial agents was observed in 49, 50, and 37% of the isolates recovered from conveyers, beef trimmings, and ground beef, respectively. The RAPD pattern data showed that the majority of resistant E. coli isolates were genetically diverse. Only a few RAPD types of resistant strains were shared among various sample sources. The results of this study suggest that antimicrobial-resistant E. coli isolates were prevalent during all stages of commercial beef processing and that considerably higher numbers of resistant E. coli were present on conveyers, beef trimmings, and ground beef than on dressed carcasses. This stresses the need for improving hygienic conditions during all stages of commercial beef processing and meatpacking to avoid the risks of transfer of antimicrobial-resistant bacteria to humans.

Patterns of antimicrobial resistance observed in Escherichia coli isolates obtained from domestic- and wild-animal fecal samples, human septage, and surface water

A repeated cross-sectional study was conducted to determine the patterns of antimicrobial resistance in 1,286 Escherichia coli strains isolated from human septage, wildlife, domestic animals, farm environments, and surface water in the Red Cedar watershed in Michigan. Isolation and identification of E. coli were done by using enrichment media, selective media, and biochemical tests. Antimicrobial susceptibility testing by the disk diffusion method was conducted for neomycin, gentamicin, streptomycin, chloramphenicol, ofloxacin, trimethoprim-sulfamethoxazole, tetracycline, ampicillin, nalidixic acid, nitrofurantoin, cephalothin, and sulfisoxazole. Resistance to at least one antimicrobial agent was demonstrated in isolates from livestock, companion animals, human septage, wildlife, and surface water. In general, E. coli isolates from domestic species showed resistance to the largest number of antimicrobial agents compared to isolates from human septage, wildlife, and surface water. The agents to which resistance was demonstrated most frequently were tetracycline, cephalothin, sulfisoxazole, and streptomycin. There were similarities in the patterns of resistance in fecal samples and farm environment samples by animal, and the levels of cephalothin-resistant isolates were higher in farm environment samples than in fecal samples. Multidrug resistance was seen in a variety of sources, and the highest levels of multidrug-resistant E. coli were observed for swine fecal samples. The fact that water sample isolates were resistant only to cephalothin may suggest that the resistance patterns for farm environment samples may be more representative of the risk of contamination of surface waters with antimicrobial agent-resistant bacteria.