Evaluation of meat, fruit and vegetables from retail stores in five United Kingdom regions as sources of extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli.

We determined the prevalence and types of extended-spectrum ß-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli in raw retail beef, chicken, pork, fruit and vegetables in five UK regions in 2013-14. Raw meat (n=397), and fruit and vegetable samples (n=400) were purchased from retail stores in London, East Anglia, North West England, Scotland and Wales. Samples were tested for the presence of ESBL-producing E. coli by plating enriched samples on CHROMagar CTX and CHROMagar ESBL, for AmpC-type E. coli by plating on "CHROMagar FOX" (CHROMagar ECC+16mg/L cefoxitin), and for carbapenem-resistant E. coli by plating on CHROMagar KPC. Additionally, pre-enrichment counts were performed on the above agars, and on CHROMagar ECC. Isolates of interest were characterised by MALDI-ToF to confirm identification, by PCR for blaCIT,blaCTX-M,blaOXA, blaSHV and blaTEM genes; ESBL or blaCIT genes were sequenced. Only 1.9% and 2.5% of beef and pork samples, respectively were positive for ESBL-producing E. coli after enrichment compared with 65.4% of chicken samples. 85.6% positive samples from chicken meat carried blaCTX-M-1; blaCTX-M-15 was not detected. None of the fruits or vegetables yielded ESBL-producing E. coli and none of the meat, fruit or vegetable samples yielded carbapenem-resistant E. coli. Retail chicken was more frequently a source of ESBL-producing E. coli than were beef, pork, fruit or vegetables. None of the foodstuffs yielded E. coli with CTX-M-15 ESBL, which dominates in human clinical isolates in the UK, and none yielded carbapenem-resistant E. coli.

A cluster of Listeria monocytogenes infections in hospitalised adults, Midlands, England, February 2011.

Hospital-acquired listeriosis cases are not commonly reported but remain a significant public health problem. We report on three cases in patients with underlying conditions occurring during one week in February 2011. The cases had common exposure to pre-packed sandwiches and salads manufactured in compliance with regulations. Breaches in cold chain and shelf life controls at hospital level were identified as key contributing factors. Rigorous hospital food management systems remain important for patient safety.

Microbiological study of fresh herbs from retail premises uncovers an international outbreak of salmonellosis.

This Local Authorities Co-ordinators of Regulatory Services/Health Protection Agency study was prompted by the increasing concern regarding the microbiological safety of ready-to-eat salad vegetable products, particularly fresh herbs. During May to October 2007, 3760 ready-to-eat fresh herbs, of different varieties, were sampled across the UK to assess their microbiological safety in relation to salmonella contamination and levels of Escherichia coli. Sixty (1.6%) herb samples were found to be of unsatisfactory quality according to Regulation (EC) No. 2073/2005 on the microbiological criteria of foodstuffs, i.e. contaminated with Salmonella spp. and/or containing E. coli at >10(3) cfu/g. When criteria in the PHLS Microbiological Guidelines for some ready-to-eat foods (2000) were used, 117 (3.9%) of herb samples were of unsatisfactory quality due to the presence of salmonella and/or E. coli at > or = 10(2) cfu/g. Eighteen (0.5%) samples of six different herb types were contaminated with Salmonella spp.: identified as serotypes Senftenberg (8), Agona (2), Anatum (1), Durban (1), Javiana (1), Mgulani (1), Montevideo (1), Unnamed (I 16:g, t: z42) (1), Virchow (1) and mixed Newport & Virchow (1). In each case the retailer and the UK Food Standards Agency were immediately informed and remedial action taken. Samples contaminated with S. Senftenberg were specifically associated with basil grown in Israel. Thirty-two human cases of S. Senftenberg infection were subsequently identified throughout England and Wales and a further 19 in Scotland, Denmark, The Netherlands and the USA. The strain of S. Senftenberg identified from the basil and that from cases had an indistinguishable molecular profile, suggesting a likely connection between consumption of basil and human infection. The presence of Salmonella spp. is unacceptable in ready-to-foods such as fresh herbs. This study highlights the necessity of applying good agricultural and hygiene practices pre-, during and post-harvest, at processing, retail and use. These practices help to prevent cross-contamination and/or bacterial growth occurring in these products. Best practice is to store and display such products at, or below, 8 degrees C as this inhibits bacterial growth.

Persistence of Campylobacter species, strain types, antibiotic resistance and mechanisms of tetracycline resistance in poultry flocks treated with chlortetracycline.

OBJECTIVES: The aim of this study was to investigate the persistence of Campylobacter species, strain types, antibiotic resistance and mechanisms of tetracycline resistance in poultry flocks treated with chlortetracycline. METHODS: Three commercially reared broiler flocks, naturally colonized with Campylobacter, were treated with chlortetracycline under experimental conditions. The numbers of Campylobacter isolated, and the species, flaA short variable region allele, and antimicrobial resistance of isolates were determined. RESULTS: For two of three flocks, tetracycline-resistant strains predominated prior to chlortetracycline exposure. Presence of the antibiotic had no discernible effect on the numbers or types of Campylobacter and the tetracycline-resistant strains persisted in numbers similar to those observed before treatment. With all flocks, some faecal samples were obtained that contained no Campylobacter, irrespective of exposure to chlortetracycline; this was more common as the birds grew older. For the third flock, tetracycline-resistant Campylobacter were in the minority of samples before and during exposure to chlortetracycline, but at sampling times after this, no resistant strains were found in the treated (or untreated) birds, irrespective of exposure to the antibiotic. All tetracycline-resistant isolates (MICs 16 to >128 mg/L) contained tet(O) and, for some isolates, this was transferable to Campylobacter jejuni 81116. The efflux pump inhibitor PAbetaN reduced the MICs of tetracycline for these isolates by 4-fold, suggesting that an intact efflux pump, presumably CmeABC, is required for high-level tetracycline resistance. CONCLUSIONS: Our data indicate that chlortetracycline treatment does not eradicate tetracycline-resistant Campylobacter spp. from poultry. However, if a low number of resistant isolates are present, then the antibiotic pressure appears insufficient to select such strains as the dominant population.

Differentiation of metronidazole-sensitive and -resistant clinical isolates of Helicobacter pylori by immunoblotting with antisera to the RdxA protein.

Antimicrobial resistance in Helicobacter pylori is a serious and increasing problem, and the development of rapid, reliable methods for detecting resistance would greatly improve the selection of antibiotics used to treat gastric infection with this organism. We assessed whether detection of the RdxA protein could provide the basis for determining the susceptibility of H. pylori to metronidazole. In order to raise polyclonal antisera to RdxA, we cloned the rdxA gene from H. pylori strain 26695 into the commercial expression vector pMAL-c2, purified the resultant fusion protein by affinity chromatography, and used this recombinant RdxA preparation to immunize rabbits. We then used this specific anti-RdxA antibody to perform immunoblotting on whole bacterial cell lysates of 17 metronidazole-sensitive and 27 metronidazole-resistant clinical isolates of H. pylori. While a 24-kDa immunoreactive band corresponding to the RdxA protein was observed in all metronidazole-sensitive strains, this band was absent in 25 of 27 resistant isolates. Our results indicate that testing for the absence of the RdxA protein would identify the majority of clinical isolates that will respond poorly to metronidazole-containing eradication regimens and have implications for the development of assays capable of detecting metronidazole resistance in H. pylori.