Vancomycin-variable enterococci in sheep and cattle isolates and whole-genome sequencing analysis of isolates harboring vanM and vanB genes

Background

Vancomycin resistance encoded by the vanA/B/M genes in enterococci is clinically important because of the transmission of these genes between bacteria. While vancomycin resistance is determined by detecting only vanA and vanB genes by routine analyses, failure to detect vanM resistance causes vancomycin resistance to be overlooked, and clinically appropriate treatment cannot be provided.

Aims

The study aimed to examine the presence of vanM-positive enterococcal isolates in Ankara, Turkey, and to have detailed information about them with sequence analyses.

Methods

Caecal samples were collected from sheep and cattle during slaughter at different slaughterhouses in Ankara, Turkey. Enterococci isolates were identified, confirmed, and analyzed for the presence of vanA/B/M genes. Antibiotic resistance profiles of isolates were determined by the broth microdilution method. A whole genome sequence analysis of the isolates harboring the vanM and vanB genes was performed.

Results

13.7% of enterococcal isolates were determined as Enterococcus faecium and Enterococcus faecalis. 15% of these isolates contained vanB, and 40% were vanM-positive. S98b and C32 isolates were determined to contain 16 CRISPR-Cas elements. 80% of the enterococci isolates were resistant to nitrofurantoin and 15% to ciprofloxacin. The first vanM-positive vancomycin-variable enterococci (VVE) isolates from food-producing animals were identified, and the S98b strain has been assigned to Genbank with the accession number CP104083.1.

Conclusion

Therefore, new studies are needed to facilitate the identification of vanM-resistant enterococci and VVE strains.

Efficacy of peroxyacetic acid against Salmonella biofilms and as a decontaminant agent in poultry meat

We aimed to investigate the effect of the post-chilling Peroxyacetic Acid (PAA) application on chicken carcasses’ shelf life, PAA treatment on chicken neck skin samples contaminated with S. Enteritidis and S. Typhimurium serotypes, and its activity against single and mixed Salmonella biofilms. Initially, effects of the post-chilling PAA application on chicken carcasses’ shelf life was analyzed. Secondly, the effectiveness of PAA application in chicken neck skin samples which are experimentally contaminated was investigated. Then, biofilm forming capacity of Salmonella enterica serovars were determined, and PAA activity against single and mixed Salmonella biofilms was evaluated. According to the results, in all experimental groups at least 1 log cfu/g reduction was observed on the day of PAA application (0 hour), and we monitored significant decreases of Salmonella counts in all groups after both 100 and 200 ppm PAA treatments within the 6th hour. The combinations of PAA concentrations and duration of application used in the study were insufficient in terms of S. Typhimurium and S. Enteritidis counts in chicken neck skin samples; however, these treatments can be effective on extending the chicken meat’s shelf life. On the other hand, 200 ppm of PAA was effective in reducing S. Typhimurium and S. Enteritidis biofilms. As a mean of 4.8 log/ml reduction were detected against S. Enteritidis and S. Typhimurium biofilms. Moreover, we can conclude from statistical analysis that when biofilm is composed with more than one Salmonella, it is harder to reduce their counts with PAA treatments. However, there is a recommendation of EFSA (European Food Safety Authority) that PAA may be a decontamination agent in poultry production in the future, considering that PAA will not have toxic effects on human health. PAA studies on this subject will be of great importance in the future if it is passed to legislation.

Campylobacter anatolicus sp. nov., a novel member of the genus Campylobacter isolated from feces of Anatolian Ground Squirrel (Spermophilus xanthoprymnus) in Turkey

Seventy-four Gram-negative, motile, slightly curved rod-shaped, microaerophilic, oxidase-positive and catalase-negative isolates, recovered from fecal samples of the Anatolian ground squirrel (Spermophilus xanthoprymnus) in Kayseri, Turkey, were subjected to a polyphasic taxonomic study. Results of a genus-specific PCR indicated that all isolates belonged to the genus Campylobacter. 16S rRNA gene sequence analyses revealed the closest match as Campylobacter curvus DSM 6644^T with identity levels of 96.41-96.70%. Based on the 16S rRNA gene phylogeny of the 74 isolates, six isolates (faydin-G24, faydin-G52, faydin-G105, faydin-G114, faydin-G129 and faydin-G140^T) were chosen as representatives for further characterization. The overall genome relatedness indices for the strain faydin-G140^T, compared to the most closely related type strain C. curvus ATCC 35224^T, were calculated as 15.2%, 72.5%, and 83.7% for digital DNA-DNA hybridization (dDDH), and average nucleotide identity (ANIb and ANIm), respectively. The G+C content and genome size of the strains ranged between 35.2-35.4 mol% and 1.7-1.8 Mb, respectively. Based on data obtained from the polyphasic taxonomy approach, including phenotypic characterization as well as genomic and chemotaxonomic analyses, these strains are concluded to represent a novel species, for which the name Campylobacter anatolicus sp. nov. is proposed with faydin-G140^T as the type strain (=DSM 112311^T = LMG 32238^T).

Plasmid-Mediated Colistin Resistance in Escherichia coli O157:H7 Cattle and Sheep Isolates and Whole-Genome Sequence of a Colistin-Resistant Sorbitol Fermentative Escherichia coli O157:H7

The aims of this study were to investigate the plasmid-mediated colistin resistance genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5), phenotypic colistin resistance in Escherichia coli O157:H7⁺/H7^- strains isolated from cattle and sheep, and whole-genome sequence (WGS) analysis of colistin-resistant sorbitol fermentative E. coli O157:H7. According to the results, 5 of the 49 isolates were found to harbor mcr-2 and/or mcr-3 genes. Three isolates, including a sorbitol fermentative E. coli O157:H7, were found phenotypically resistant to colistin with a minimum inhibitory concentration value of 128 μg/mL. The genome of sorbitol fermentative E. coli O157:H7 did not show 100% similarity to any of the other genome sequences found in the universal genome database. It has also been determined that this isolate carried 62 different antimicrobial resistance genes. This is the first report of plasmid-mediated mcr-2 and mcr-3 genes carrying E. coli O157:H7 from cattle and sheep isolates and WGS of a colistin-resistant sorbitol fermentative E. coli O157:H7. Findings of this study indicate that cattle and sheep can be an important source of colistin resistance in E. coli O157:H7, and slaughterhouse wastewater might be a significant route for dissemination of the plasmid-mediated colistin genes. Therefore, the use of colistin in veterinary medicine should be restricted to reduce the development of resistance. Also it may be necessary to review the non-sorbitol fermentation-based isolation protocol for not missing the sorbitol fermentative E. coli O157:H7 in epidemiological studies.

Prevalence and Characterization of Listeria monocytogenes Isolated from Beef and Sheep Carcasses in Turkey with Characterization of Locally Isolated Listeriophages as a Control Measure

Swab samples from cattle and sheep carcasses (120 of each) were tested for Listeria monocytogenes, and 120 slaughterhouse wastewater samples were tested for listeriophages over 12 months (10 samples per month) to note the seasonal distribution. L. monocytogenes and bacteriophage isolates were characterized, and the biocontrol of L. monocytogenes was investigated in meatballs with a phage cocktail. L. monocytogenes was found in 3.4 and 2.5% of cattle and sheep carcasses, respectively. All the isolates were found to harbor hlyA, actA, inlA, inlB, inlC, inlJ, plcA, plcB, fbpA, and fri genes with varied mRNA expression levels by real-time reverse transcriptase PCR analysis. Five isolates did not harbor the vip gene. According to enterobacterial repetitive intergenic consensus PCR, L. monocytogenes isolates were classified into four different groups based on their DNA patterns. The L. monocytogenes isolates were characterized for antibiotic susceptibility; one strain was found to be resistant to five different antibiotic classes. Of 11 lytic listeriophages, two were selected for the cocktail based on their DNA restriction profiles, efficiency of plating, transmission electron microscopy, and in vitro and in vivo analyses. In the biocontrol study, we used a food model that consisted of a novel bacteriophage cocktail in raw meatballs. The highest reduction of L. monocytogenes was recorded as 2.2 log CFU/g at a multiplicity of cellular infection of 4.7 at the end of 1 h. In conclusion, the new bacteriophage cocktail in this study can be considered an efficient biocontrol agent of L. monocytogenes in meatballs.

COMPARISON OF PREVALENCE AND GENETIC DIVERSITY OF ESCHERICHIA COLI O157:H7 IN CATTLE AND SHEEP

In this study the prevalence of Escherichia coli O157:H7 was detected by immunomagnetic separation (IMS) based cultivation technique and polymerase chain reaction (PCR) in feces and/or colon tissue of cattle (n= 282) and sheep (n= 218) at slaughterhouse. The major virulence genes, intimin variants, Shiga toxin variants and antibiotic resistance genes of the isolates were examined by PCR and genomic diversity of the cattle and sheep E. coli O157:H7 isolates were assessed using pulsed field gel electrophoresis (PFGE). In the present study the prevalence of E.coli O157:H7 was found higher in sheep (6.4 %) than in cattle (3.9 %). All the E.coli O157:H7 isolates were detected as positive for at least one stx gene and positive for other virulence genes. Twelve (29.3 %) and one (2.4 %) of the cattle isolates carried stx2 and stx1 gene, respectively. However 11 (17.7 %) of the sheep E. coli O157:H7 isolates carried stx2 and five (8.1 %) of the isolates harbored stx1 gene only. At least one antibiotic resistance gene was detected from 35 isolates. E. coli O157:H7 isolates from four sheep and three cattle harbored tetB gene. From three cattle and one sheep samples strA carrying E. coli O157:H7 were isolated. Among them, isolates from 2 cattle and one sheep samples were carried both tetB and strA. Isolates were grouped into six different clusters. From a cattle and a sheep, two different E. coli O157:H7 which have different PFGE patterns, were isolated. It can be concluded that sheep pose a risk as cattle for STEC O157:H7 contamination in Turkey.