Methicillin-resistant Staphylococcus aureus (MRSA) strains belonging to sequence type (ST) 398 are being reported with increasing frequency in Europe and other countries. This MRSA type has been isolated from colonized and infected animals and humans. The aim of this study was to determine the prevalence of nasal MRSA carriage in pigs and pig workers. A total of 300 pigs from 15 different farms were sampled in the slaughterhouse of Tenerife. A total of 54 pig workers were screened for MRSA: 20 belonged to farms whose pigs had been sampled and 34 to the slaughterhouse. The percentage of positive samples of MRSA in pigs was 85.7%. The overall prevalence of nasal MRSA carriage in pig workers was 9.3%. All MRSA isolates from pigs and humans belonged to one clonal group showing multilocus sequence type (MLST) 398. Two types of Staphylococcal Chromosome Cassette (SCCmec) were found, IV and V. In conclusion, the prevalence of MRSA in nasal samples from pigs and pig workers in Tenerife was high. We therefore consider it essential to deepen epidemiological study of this strain of animal origin, as well as to increase surveillance and control measures at all stages of the food chain.

To determine the prevalence of Salmonella enterica serotypes in imported frozen chicken meat, 406 samples (whole chicken, legs, and breast meat) were analyzed for Salmonella according to ISO6579 rules, serotypes were assigned, and phage typing was conducted for Salmonella serotypes Enteritidis, Typhimurium, and Heidelberg. The overall frequency of Salmonella isolation was 16.5%. By country of origin, the highest percentage of cases was found among the samples from France followed by samples from Brazil. The differences between legs and breast meat were significant. The most frequently isolated serotype of Salmonella was Enteritidis, followed by Salmonella Heidelberg, Salmonella Typhimurium, and Salmonella Virchow. By country of origin, we identified a large percentage of serotype Salmonella Enteritidis in the samples imported from Brazil. There was a greater diversity of serotypes isolated from the French samples, and Salmonella Enteritidis was not the dominant strain. In the samples from the United States, the only serotype isolated was Salmonella Kentucky, although a smaller number of samples was analyzed. The Salmonella Enteritidis phage type that prevailed in both France and Brazil was 4. Phage types 204c and 204 were identified for Salmonella Typhimurium, and phage types 8, 31, and 37 were identified for Salmonella Virchow.

In order to analyze the antibiotic resistance of Salmonella enterica serovars, a total of 112 Salmonella strains were tested (54 S. enteritidis, 32 S. typhimurium, 11 S. heidelberg, 7 S. infantis, 4 S. virchow and 4 S. hadar). The bacteria were isolated from 691 samples of frozen and fresh chicken meat. Identification of microorganisms and antimicrobial sensitivity testing were undertaken by means of the automated MicroScan AutoScan 4 method (Baxter in Spain). 45.5% of 112 strains tested were susceptible to all antibiotics. The highest percentage of resistance was found to: chloramphenicol (44.6%), ampicillin (34.8%) and tetracycline (33.9%). Multiple resistance was observed in 49 strains (43.7%), whereas single resistance was seen in 12 isolates (10.7%). We found 12 different patterns of resistance in Salmonella enterica serovar enteriditis. Resistance to chloramphenicol was the most common single resistance. The most frequent patterns of multiresistant strains were ampicillin + amoxicillin/clavulanate + cefazolin + imipenem and chloramphenicol + impipenem. In this serotype, 49 isolates belonged to phagetype 4. Salmonella typhimurium showed the highest percentages of resistance to the tested drugs, with six different resistance patterns found. 25 strains out of 32 S. typhimurium isolates belonged to phagotype 120 and 13 of these showed the same resistance pattern: chloramphenicol + tetracycline + ampicillin. The high incidence of antibiotic resistant salmonellae found in chickens in our study suggests the need for public health interventions to decrease selective pressure on bacterial strains by antimicrobial agents.