Antimicrobial Resistance in Enterococcus Spp. Isolated from a Beef Processing Plant and Retail Ground Beef.

Antimicrobial use in food-producing animals has come under increasing scrutiny due to its potential association with antimicrobial resistance (AMR). Monitoring of AMR in indicator microorganisms such as Enterococcus spp. in meat production facilities and retail meat products can provide important information on the dynamics and prevalence of AMR in these environments. In this study, swabs or samples were obtained from various locations in a commercial beef packing operation (n = 600) and from retail ground beef (n = 60) over a 19-month period. All samples/swabs were enriched for Enterococcus spp., and suspected enterococci isolates were identified using species-specific PCR primers. Enterococcus faecalis was the most frequently isolated species, followed by Enterococcus hirae, which was found mostly on post-hide removal carcasses and in ground beef. Enterococcus faecium (n = 9) and E. faecalis (n = 120) isolates were further characterized for AMR. Twenty-one unique AMR profiles were identified, with 90% of isolates resistant to at least two antimicrobials and two that were resistant to nine antimicrobials. Tetracycline resistance was observed most often in E. faecalis (28.8%) and was likely mediated by tet(M). Genomic analysis of selected E. faecalis and E. faecium isolates revealed that many of the isolates in this study clustered with other publicly available genomes from ground beef, suggesting that these strains are well adapted to the beef processing environment. IMPORTANCE Antimicrobial resistance (AMR) is a serious challenge facing the agricultural industry. Understanding the flow of antimicrobial-resistant bacteria through the beef fabrication process and into ground beef is an important step in identifying intervention points for reducing AMR. In this study, we used enterococci as indicator bacteria for monitoring AMR in a commercial beef packaging facility and in retail ground beef over a 19-month period. Although washing of carcasses post-hide removal reduced the isolation frequency of Enterococcus spp., a number of antimicrobial-resistant Enterococcus faecalis isolates were recovered from ground beef produced in the packaging plant. Genome analysis showed that several E. faecalis isolates were genetically similar to publicly available isolates recovered from retail ground beef in the United States.

Prevalence and antimicrobial resistance of Salmonella isolated from two pork processing plants in Alberta, Canada.

This study investigated the frequency of Salmonella serovars on pig carcasses at various processing steps in two commercial pork processing plants in Alberta, Canada and characterized phenotypic and genotypic antimicrobial resistance (AMR) and PFGE patterns of the Salmonella isolates. Over a one year period, 1000 swab samples were collected from randomly selected pigs at two slaughter plants. Sampling points were: carcass swabs after bleeding (CSAB), carcass swabs after de-hairing (CSAD, plant A) or skinning (CSASk, plant B), carcass swabs after evisceration (CSAE), carcass swabs after pasteurization (CSAP, plant A) or washing (CSAW, plants B) and retail pork (RP). For plant A, 87% of CSAB and 8% of CSAE were positive for Salmonella while at plant B, Salmonella was recovered from 94% of CSAB and 10% of CSAE. Salmonella was not recovered from the RP samples at either plant, indicating that the plants used effective control measures. Salmonella enterica serovar Derby was the most common serotype (23%, 29/127) recovered in plant A and plant B (61%, 76/124). For plant A, 35% (45/127) of isolates were resistant to at least one antimicrobial. Five isolates (3.9%), 4 serovar Ohio strains and one serovar I:Rough-O:I,v:-, strain were simultaneously resistant to antimicrobials of very high (Category I), high (Category II), and medium (Category III) importance to human medicine. The 4 S. Ohio isolates were recovered from 3 different steps of pork processing on the same sampling day and displayed resistance to 5-7 antimicrobials, with all of them displaying resistance to ceftiofur and ceftriaxone (Category I). An I:Rough-O:l,v:- isolate, recovered on a different sampling day, was resistant to 7 antimicrobials that included resistance to ampicillin/clavulanic acid, ceftiofur and ceftriaxone (Category I). Salmonella strains isolated from plant A harbored 12 different AMR genes. The most prevalent genes were sul1, sul2, tet(A), tet(B), aadA, strA/strB, aac(3)IV and aphA1. For Salmonella isolates from plant B, 7 resistance genes were identified alone or in combination where tet(B) was found in 77 (62.3%) of the isolates. For plant A, 19 different PFGE subtypes of Salmonella isolates that displayed phenotypic and/or genotypic resistance were observed while 13 different PFGE subtypes were observed for plant B. The lack of detection of Salmonella on the surfaces of RP suggests that current pork processing practices can dramatically reduce Salmonella. Salmonella isolates from pig carcasses at various steps displayed multidrug resistance, including to those of very high importance in human medicine, which represent a public health concern.

Characterization of antimicrobial resistance in Enterococcus spp. recovered from a commercial beef processing plant.

The objective of this study was to characterize antimicrobial resistance in Enterococcus spp. recovered from a commercial beef processing plant. Samples were obtained from conveyers used for moving carcasses before the start of operation (CC), 2 h after operation has started (DC), and from ground beef (GB). Randomly selected isolates from each positive sample (13 from CC; 28 from DC; 26 from GB) were confirmed to genus and species levels using PCR and the API 20 Strep kit (BioMérieux Canada, Inc., St. Laurent, Canada). A total of 199 isolates comprising 39, 84, and 76 from CC, DC, and GB, respectively, were used for antimicrobial resistance testing, major resistance genes detection, and genetic analysis. Enterococcus faecalis (87%) was the most common species found followed by Enterococcus faecium (10%). The majority of enterococci were highly associated with DC samples. About 42% of E. faecium from DC samples were resistant to quinupristin-dalfopristin. Resistance to lincomycin was observed in >90% of E. faecalis from all the three sample sources. The tetracycline-resistant enterococci (52%) were significantly higher in DC samples. Intermediate resistance to erythromycin was significantly higher in enterococci from CC and DC samples. The tetracycline and quinupristin-dalfopristin resistance in enterococci was highly correlated with the presence of tet(M) and vat(E) genes. The erm(B) gene was found in about 50% of the E. faecium isolates from GB samples and was also present in >12% of the E. faecalis isolates from all the three sample sources. Enterococci from individual sample sources were genetically similar. A number of E. faecalis from CC, DC, and GB were clustered together at >85% similarity level. These findings suggest that antimicrobial-resistant Enterococcus spp. are prevalent during commercial beef processing and can transfer between various locations in the plant and that a pool of resistance genes can be found in these enterococci.

Antimicrobial resistance genes in Escherichia coli isolates recovered from a commercial beef processing plantt.

The goal of this study was to assess the distribution of antimicrobial resistance (AMR) genes in Escherichia coli isolates recovered from a commercial beef processing plant. A total of 123 antimicrobial-resistant E. coli isolates were used: 34 from animal hides, 10 from washed carcasses, 27 from conveyers for moving carcasses and meat, 26 from beef trimmings, and 26 from ground meat. The AMR genes for beta-lactamase (bla(CMY), bla(SHV), and bla(TEM), tetracycline (tet(A), tet(B), and tet(C)), sulfonamides (sul1, sul2, and sul3), and aminoglycoside (strA and strB) were detected by PCR assay. The distribution of tet(B), tet(C), sul1, bla(TEM), strA, and strB genes was significantly different among sample sources. E. coli isolates positive for the tet(B) gene and for both strA and strB genes together were significantly associated with hide, washed carcass, and ground meat samples, whereas sull gene was associated with washed carcass and beef trimming samples. The bla(TEM) gene was significantly associated with ground meat samples. About 50% of tetracycline-resistant E. coli isolates were positive for tet(A) (14%), tet(B) (15%), or tet(C) (21%) genes or both tet(B) and tet(C) genes together (3%). The sul2 gene or both sul1 and sul2 genes were found in 23% of sulfisoxazole-resistant E. coli isolates, whereas the sul3 gene was not found in any of the E. coli isolates tested. The majority of streptomycin-resistant E. coli isolates (76%) were positive for the strA and strB genes together. The bla(CMY), bla(TEM), and bla(SHV) genes were found in 12, 56, and 4%, respectively, of ampicillin-resistant E. coli isolates. These data suggest that E. coli isolates harboring AMR genes are widely distributed in meat processing environments and can create a pool of transferable resistance genes for pathogens. The results of this study underscore the need for effective hygienic and sanitation procedures in meat plants to reduce the risks of contamination with antimicrobial-resistant bacteria.

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.