This study estimated the prevalence of Escherichia coli isolates in fresh retail milk-fed veal scallopini pieces obtained from grocery stores in Ontario, Canada. In addition, the prevalence and antimicrobial resistance patterns were examined for points of public health significance. One hundred fifty-three milk-fed veal samples were collected over the course of two sampling phases, January to May 2004 and November 2004 to January 2005. E. coli isolates were recovered from 87% (95% confidence interval, 80.54 to 91.83%) of samples, and antimicrobial susceptibility testing was conducted on 392 isolates. The prevalence of resistance to one or more antimicrobials was 70% (274 of 392), while the resistance to five or more antimicrobials was 33% (128 of 392). Resistance to ceftiofur (2.8%), ceftriaxone (3.6%), nalidixic acid (12%), and ciprofloxacin (3.8%) alone or in combination was observed. Eighty-five resistance patterns were observed; resistance to tetracycline only (7.4%) was observed most frequently. Individual antimicrobial resistance prevalence levels were compared with grain-fed veal and retail beef data from samples collected in Ontario. In general, resistance to individual antimicrobials was observed more frequently in E. coli isolates from milk-fed veal than in isolates from grain-fed veal and beef. Resistance to one or more antimicrobials and to five or more antimicrobials in E. coli isolates was more frequent in isolates from milk-fed veal than in isolates from grain-fed veal and beef. This study provides baseline data on the occurrence of resistance in E. coli isolates from milk-fed veal that can be compared with data for other commodities. Additionally, E. coli resistance patterns may serve as an indicator of antimicrobial exposure.
To investigate occurrence of acquired antimicrobial resistance in udder pathogens MICs in Staphylococcus aureus (n=211), coagulase-negative staphylococci (CNS) (n=56), Streptococcus uberis (n=113), Streptococcus dysgalactiae (n=152), Streptococcus agalactiae (n=6), Escherichia coli (n=163), and Klebsiella spp. (n=42) were determined using microdilution. Isolates were from a nation wide survey employing strict inclusion criteria. Presence of acquired resistance was evaluated by species-specific epidemiological cut-off values issued by EUCAST. Penicillin or methicillin resistance in staphylococci were however evaluated by beta-lactamase production or presence of the mecA gene, respectively. Staphylococci were mostly susceptible to antimicrobials tested but 7.1% of S. aureus and 12.5% of CNS were resistant to penicillin by beta-lactamase production. Methicillin resistance was not found in S. aureus. All Streptococcus dysgalactiae and S. agalactiae were susceptible to penicillin. Bimodal MIC distributions for tetracycline in S dysgalactiae and S. uberis indicate acquired resistance in some isolates. Among E. coli 12.3% of isolates were resistant to one or more antimicrobials. Resistance to streptomycin (11.0%), sulphametoxazole (8.6%), ampicillin (7.4%), or tetracycline (4.9%) were the most common traits. Klebsiella spp. were resistant to ampicillin and some isolates also to tetracycline (7.1%) or sulphonamide (9.5%). The study shows that in Sweden bacteria associated with acute clinical mastitis for the most part are susceptible to antimicrobials used in therapy but resistance to penicillin in S. aureus is not uncommon. Penicillin is recommended for treatment of mastitis caused by gram-positive pathogens and regular monitoring of beta-lactamase production in S. aureus is therefore recommended in herds with udder health problems.
The aim of this study was to investigate the occurrence of Arcobacter species in raw milk in Finland. A total of 177 raw milk samples, each from a separate farm, were examined from June to August 2011. Arcobacter species were isolated using an enrichment and selective detection procedure. Overall, 26 (15 % ) of the 177 samples yielded Arcobacter spp. Samples from 25 farms were positive for Arcobacter butzleri and from 1 farm for Arcobacter cryaerophilus. Moreover, both Arcobacter butzleri and A. cryaerophilus were recovered from 1 positive sample. To evaluate a possible genetic variability, one strain of A. butzleri from each farm and the A. cryaerophilus sample were analyzed by pulsed-field gel electrophoresis. Genotyping revealed that Arcobacter spp. populations are heterogeneous, and no dominant clone has spread in the investigated samples. Our study is the first report on the isolation of both A. butzleri and A. cryaerophilus in raw milk in Finland. Based on our findings, the presence of Arcobacter species in raw milk may pose a potential hazard for human health, in particular for consumers who prefer drinking unpasteurized milk.
Microbial contamination of bovine raw milk often occurs at the farm. To acquire a deeper knowledge of the microbiota of farm tank milk, we studied milk from 45 farms situated in 2 geographical areas in Norway. Each farm was visited on 3 different occasions, with at least 2 wk between visits. We combined both bacterial cell counts and a sequence variant inference method of amplicon-based high-throughput sequencing to achieve a high-resolution overview of the microbiota in each sample. Compositional variation of the farm milk microbiota was shown in relation to the 2 areas, between the farms and between the sampling times. Despite the near constant level of bacteria enumerated in milk from each individual farm, the dominant microbiota differed significantly between the samplings. The predominant microbiota was dominated by spoilage genera, such as Pseudomonas and Bacillus, as well as the dairy fermentation genus Lactococcus and mastitis-causing organisms (Streptococcus). Analysis of the identified sequence variants within these genera showed that the populations of Pseudomonas and Lactococcus in milk had similar composition between the farms, but that Bacillus and, in particular, Streptococcus populations changed between collection days from the same farm and between farms and geographical areas. Furthermore, the levels and composition of Bacillus and Paenibacillus were different between the 2 geographical areas. The results presented here provide new insight into the farm milk microbiota and show that this microbiota is a dynamic community highly subject to variation.
The objective of this study was to evaluate the diagnostic performance of two ELISA tests applied to bulk tank milk (BTM) as the first part of a two-step test scheme for the surveillance of caprine arthritis encephalitis (CAE) and caseous lymphadenitis (CLA) infections in goats. The herd-level BTM tests were assessed by comparing them to the test results of individual serological samples. The potential for refining the cut-off levels for BTM tests used as surveillance tools in a population recently cleared of infection was also investigated. Data was gathered on serum (nCAE =9702 and nCLA=13426) and corresponding BTM (nCAE=78 and nCLA=123) samples from dairy goat herds enrolled in the Norwegian disease control and eradication programme 'Healthier Goats'. The results showed that the sensitivity and specificity of the CAE ELISA BTM test with respect to detecting =2 per cent within-herd prevalence were 72.7 per cent and 86.6 per cent, respectively. For the CLA ELISA BTM the sensitivity and specificity were 41.4 per cent and 81.7 per cent, respectively, for the same goal of detection. The results suggest that BTM testing can be applied as a cost-effective first step for early detection of CAE and CLA infection.
Cell surface proteins of two slime-forming, encapsulated Streptococcus cremoris strains, MLS96 and T5 from the fermented milk product viili, were extracted with the non-ionic detergent Triton X-100. The isolated protein antigens were characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting with antisera produced against whole Strep. cremoris cells. When protein profiles of these strains were compared, seven prominent polypeptides were found common to both and were recognized by both antisera. Five of these polypeptides with molecular weights of 70,000, 54,000, 50,000, 47,000 and 40,000 were identified as cell wall components. The remaining two polypeptides with molecular weights of 42,000 and 26,000 are being studied further in connection with slime formation for which modified Triton X-100 extraction provides a suitable method for isolation of the surface-associated antigens of lactic streptococci.
A total of 84 strains of Listeria monocytogenes were analysed by multilocus enzyme electrophoresis at twelve enzyme loci. Eight enzyme loci were polymorphic with between 2 and 4 alleles per locus. Fourteen electrophoretic types (ETs) were identified. Among 62 human clinical isolates from Denmark, 8 different ETs were defined. Two ETs, designated ET 1 and ET 6, accounted for 77% of the human clinical isolates investigated. These ETs are identical with those responsible for several epidemics in Switzerland and in the United States. Comparison of 58 isolates of L. monocytogenes, typed by MEE, in relation to phage typing showed that phage typing was more discriminatory than MEE. The ability of MEE to distinguish between phage types of Epi-type and other phage types, however, was almost optimal. MEE typed 23 of 24 strains of Epi-type as belonging to ET 1. In contrast ET 1 was not found in 26 strains with phage types other than the Epi-type.