Antimicrobial resistance ofEnterococcus spp. isolates from raw beef and meat products

Global Prevalence of Vancomycin-Resistant Enterococci in Food of Animal Origin: A Meta-Analysis

Vancomycin-resistant enterococci (VRE) are a leading cause of nosocomial infections in patients worldwide. VRE contamination in food of animal origin may create a risk for human health. This study was conducted to estimate the pooled prevalence of VRE in food of animal origin worldwide, to assess the result heterogeneity, and to determine cumulative evidence and the trend of the prevalence over time. Relevant studies were retrieved from PubMed, Scopus, and Web of Science. A random-effects model was used to calculate the pooled prevalence of VRE in food of animal origin. Subgroup meta-analysis was used to assess the heterogeneity of the results. A cumulative meta-analysis and meta-regression were conducted to determine cumulative evidence and the trend of the prevalence of VRE in food of animal origin over time, respectively. Of the 1352 retrieved studies, 50 articles were included. The pooled prevalence of VRE in food of animal origin was 11.7% (95% confidence interval [95% CI] = 8.4 to 16.0). Subgroup meta-analyses showed a significant difference in the prevalence of VRE for two characteristics. First, for the source of food, the prevalence of VRE was highest in aquatic food (43.4% [95% CI = 28.4 to 59.7]) and lowest in dairy food (4.1% [95% CI = 1.7 to 9.8]). Second, for continents, the prevalence of VRE was highest in Africa (18.5% [95% CI = 12.8 to 26.1]) and lowest in North America (0.3% [95% CI = 0.1 to 1.1]). Cumulative evidence showed two distinct features in two different periods. The pooled prevalence of VRE rapidly decreased from 79.3% in 1998 to 13.1% in 2003; it has slightly fluctuated between 10.5% and 20.5% since 2004. The results of the meta-regression indicated that the prevalence gradually decreased over time. In conclusion, the estimate of overall VRE prevalence worldwide in food of animal origin was ∼12%, indicating the burden of VRE contamination in food of animal origin.

Characterization of antimicrobial resistance and virulence genotypes of Enterococcus faecalis recovered from a pork processing plant

The objective of this study was to assess the antimicrobial resistance and virulence genotypes of Enterococcus faecalis isolated from samples obtained from a commercial pork processing plant. A total of 200 samples were randomly obtained from carcasses after bleeding (BC; 50 samples) and pasteurization (PC; 100 samples) and from retail pork products (RP; 50 samples). One isolate from each E. faecalis -positive sample was analyzed for antimicrobial susceptibility and characterized using a enterococcal microarray for analysis of resistance and virulence genes. E. faecalis was isolated from 79.5% of BC samples, 2% of PC samples, and 72.7% of RP samples. Resistance to the clinically important drugs ciprofloxacin (one isolate each from BC and RP samples) and daptomycin (one isolate each from PC and RP samples) was found. Multiresistance (to five or more antimicrobials) was more common in E. faecalis isolates from BC (77.4% of isolates) samples than those from PC (25%) and RP (37.6%) samples. Resistance to kanamycin (43.5%) and streptomycin (69.2%) was noted mostly in E. faecalis from BC samples. The most common resistance genes (>5% prevalence) found in E. faecalis were those for aminoglycosides (aac(6), aphA3, and aadE), macrolides-lincosamide (ermB, ermA, sat(4), and linB), and tetracyclines (tetL, tetM, and tetO ). The virulence genes expressing adhesion (ace, efaAfs, and agrBfs), gelatinase (gelE), and pheromone (cAM, ccF10, cob, and cpd1) factors were found in the majority of isolates. Significant associations were found between resistance and virulence genes, suggesting their possible relationship. These data suggest that carcasses entering the final product processing area are mostly free of E. faecalis but are recontaminated with antimicrobial-resistant strains during processing. The source of these contaminants remains to be identified; however, these results underscore the importance of E. faecalis as a reservoir of resistance and virulence genes.

Characterization of antimicrobial resistance and virulence genes in Enterococcus spp. isolated from retail meats in Alberta, Canada

The objective of this study was to characterize antimicrobial resistance (AMR) and virulence genotypes of Enterococcus spp. particularly Enterococcus faecalis isolated from retail meats purchased (2007-2008) in Alberta, Canada. Unconditional statistical associations between AMR pheno- and genotypes and virulence genotypes were determined. A total of 532 enterococci comprising one isolate from each positive sample were analyzed for antimicrobial susceptibility. A customized enterococcal microarray was used for species identification and the detection of AMR and virulence genes. E. faecalis was found in >94% of poultry samples and in about 73% of beef and 86% of pork samples. Enterococcus faecium was not found in turkey meat and its prevalence was 2% in beef and pork and 4% in chicken samples. None of the enterococci isolates were resistant to the clinically important drugs ciprofloxacin, daptomycin, linezolid and vancomycin. Multiresistance (≥3 antimicrobials) was more common in E. faecalis (91%) isolated from chicken and turkey (91%) than those isolated from beef (14%) or pork (45%). Resistance to aminoglycosides was also noted at varying degrees. The most common resistance genes found in E. faecalis were aminoglycosides (aac, aphA3, aadE, sat4, aadA), macrolides (ermB, ermA), tetracyclines (tetM, tetL, tetO), streptogramin (vatE), bacitracin (bcrR) and lincosamide (linB). Virulence genes expressing aggregation substances (agg) and cytolysin (cylA, cylB, cylL, cylM) were found more frequently in poultry E. faecalis and were unconditionally associated with tetM, linB and bcrR resistance genes. Other virulence genes coding for adhesion (ace, efaAfs), gelatinase (gelE) were also found in the majority of E. faecalis. Significant statistical associations were found between resistance and virulence genotypes, suggesting their possible physical link on a common genetic element. This study underscores the importance of E. faecalis as a reservoir of resistance and virulence genes and their potential transfer to humans through consumption of contaminated undercooked meat.

Characteristics ofStaphylococcus aureus isolated from rabbits

The occurrence of Staphylococcus aureus in rabbit feces, cecum and meat and its enterotoxin production, susceptibility to antibiotics and its sensitivity or resistance to bacteriocins produced by enterococci with probiotic properties were determined. Isolates were resistant to ampicillin, penicillin, phosphomycin and methicillin; a high percentage of susceptibility was also recorded to vancomycin, chloramphenicol, tetracycline and tobramycin. S. aureus isolates did not produce enterotoxins and were sensitive to partially purified enterocins (PPB) EK13, AL41 and EF2019 in the range of 100 to 12800 AU/mL; all S. aureus isolates, except the strain SA 2A/3, exhibited the highest sensitivity to PPB EK13. On the other hand, all strains were resistant to PPB CCM4231.

Antimicrobial susceptibility ofEnterococcus species isolated from slovak bryndza cheese

Three hundred and ten enterococcal isolates (178 Enterococcus faecium, 68 E. durans, 49 E. faecalis, 8 E. italicus, 3 E. gallinarum, 3 E. casseliflavus, and 1 E. hirae) from Slovak Bryndza cheese were evaluated for susceptibility to nine antimicrobial agents (vancomycin, teicoplanin, ampicillin, streptomycin, gentamicin, erythromycin, rifampicin, nitrofurantoin, and ciprofloxacin). All enterococcal isolates from Bryndza cheese were susceptible to ampicillin, streptomycin, gentamicin, vancomycin, and teicoplanin as determined by the disk diffusion method. Vancomycin resistance genes vanA and vanB were not detected. Resistance rates of enterococcal isolates to rifampicin, erythromycin, ciprofloxacin, and nitrofurantoin were 24, 26, 2, and 1 %, respectively. Thirty-six % of E. faecium isolates and 22 % of the E. faecalis isolates were resistant to erythromycin. Resistance to rifampicin was similar in E. faecium (31 %) and E. faecalis (29 %). Both E. faecium and E. faecalis strains showed the same resistance to ciprofloxacin (2 %). E. durans isolates showed low levels of resistance to rifampicin, erythromycin, ciprofloxacin, and nitrofurantoin (1-4 %). Forty-eight (30 %) of the E. faecium isolates, two (3 %) of the E. durans isolates, and six (12 %) of the E. faecalis isolates exhibited multidrug resistance. The highest frequency of resistant enterococci was observed in Bryndza produced in winter season.

Seasonal dynamics of antibiotic-resistantEnterobacteriaceae in the gastrointestinal tract of domestic sheep

Considerable variation in counts of antibiotic-resistant enterobacteria in the ovine gastrointestinal tract was observed. The occurrence of ruminal and fecal isolates resistant to ampicillin (Ap), kanamycin (Km) and tetracycline (Tc) culminated in summer months, followed by rapid decline in subsequent months. Using PCR the tem1bla (Apr), aphA1 (Kmr) and tetB (Tcr) genes were found to be predominant. Under in vitro conditions all resistance genes were transferable into laboratory Escherichia coli strain with relatively high frequency (10(-3) transconjugants per recipient).