Linezolid-resistant MRSA-CC398 carrying the cfr gene, and MRSA-CC9 isolates from pigs with signs of infection in Spain.

AIMS: To perform the molecular characterization of 23 Staphylococcus aureus isolates from pigs with signs of infections recovered in Spanish farms during 2018-2019. METHODS AND RESULTS: The antimicrobial resistance pattern and virulence profile were determined. The molecular typing was performed by different molecular techniques. The transferability of the cfr gene was assessed by conjugation and its genetic environment was determined by PCR mapping. In all, 21 isolates were methicillin-resistant S. aureus (MRSA) carrying the mecA gene (SCCmecV or non-typeable SCCmec), whereas the remaining two were methicillin-susceptible (MSSA). All but one MRSA isolates (n = 20) belonged to the CC398, being the spa t011 the most prevalent (n = 11). The remaining MRSA and the two MSSA isolates were ascribed to ST9/CC9. The S. aureus isolates exhibited resistance to (number of resistant isolates): ß-lactamics (21), erythromycin and/or clindamycin (20), aminoglycosides (7), tetracycline (22), fluoroquinolones (14), chloramphenicol (5) and linezolid (1). The S. aureus isolates did not carry any of the virulence genes studied. One MRSA belonging to the CC398 showed linezolid resistance mediated by the cfr gene. The cfr gene was co-located with fexA in the Tn558 variant previously reported in the S. aureus plasmid pSCFS7. CONCLUSIONS: Two major livestock-associated genetic lineages were detected among pigs with signs of infection in Spain. The presence of the cfr gene among LA-MRSA-CC398 is of great concern not only for veterinary medicine, but also for humans in close contact. SIGNIFICANCE AND IMPACT OF THE STUDY: This work describes the molecular characterization of S. aureus isolates recovered from pigs with signs of infection and we report, as far as we know, the first description of MRSA-CC9 from pigs in Spain. Moreover, the detection of a MRSA-CC398 isolate carrying the multiresistance cfr gene highlights the need for continuous surveillance and awareness of LA-MRSA.

Enterotoxin genes and antimicrobial resistance in Staphylococcus aureus isolated from food products in Algeria.

AIMS: The aim of this study was to characterize Staphylococcusaureus isolates of food origin (dairy and meat products, pastries and sandwiches) determining the carriage in enterotoxin genes and the antimicrobial resistance pheno/genotypes. METHODS AND RESULTS: A total of 300 food samples were collected and analysed for the detection of S. aureus. The presence of enterotoxin genes was investigated by multiplex PCRs. Resistance of isolates to 11 antimicrobials was determined using disc diffusion method and molecular characterization of methicillin-resistant S. aureus was carried out by spa typing and multilocus sequence typing. Overall, 51 out of 300 samples (17%) were contaminated with S. aureus, and 104 isolates were recovered. In all, 65 of these isolates (62·5%) harboured one or more genes encoding for staphylococcal enterotoxins, being seg and sei the most observed genes. The highest resistance profile was ascribed to penicillin G (95·19%). Five isolates were methicillin-resistant (MRSA) harbouring the mecA gene. All MRSA isolates belonged to the sequence type ST5 and to two different spa types (t450 and t688); the MRSA-t450 isolate carried the scn gene (specific marker of the immune evasion cluster system), but the four MRSA-t688 isolates were scn negative. The MRSA isolates carried enterotoxin genes but were negative for the genes of the Panton Valentine leukocidine (lukF/S-PV). CONCLUSION: The presence of enterotoxigenic S. aureus isolates, including MRSA, in food samples can represent a risk for public health. SIGNIFICANCE AND IMPACT OF THIS STUDY: This work describes the molecular characteristics of MRSA strains isolated from foods in Algeria and it can contribute to an extended database concerning the S. aureus isolated from food origin.

Emergence of methicillin-resistant Staphylococcus aureus (MRSA) ST8 in raw milk and traditional dairy products in the Tizi Ouzou area of Algeria.

Staphylococcus aureus is one of the leading causes of food-borne illness worldwide. Raw milk and dairy products are often contaminated with enterotoxigenic strains of this bacterium. Some of these strains carry antimicrobial resistance, leading to a potential risk for consumers. The aim of this study was to characterize S. aureus strains circulating in raw milk and traditional dairy products for carriage of staphylococcal enterotoxin (se) genes and antimicrobial resistance. Overall, 62 out of 270 samples (23%) were contaminated with S. aureus, and 69 S. aureus strains were identified. We studied the enterotoxin genes using 2 multiplex PCR targeting 11 se genes. Seventeen (24.6%) isolates carried one or more genes encoding for staphylococcal enterotoxins. The most commonly detected se genes were seb and sep, followed by seh, sea, and see. Using the disk diffusion method, we found that resistance to penicillin G and tetracycline was the most common. Eleven isolates of methicillin-resistant S. aureus (MRSA) carried the mecA gene. All MRSA isolates belonged to the same spa type (t024) and sequence type (ST8), and carried the seb and sep enterotoxin genes. However, none of them carried the Panton Valentine leukocidin gene (lukF/S-PV). The presence of enterotoxigenic S. aureus strains, including MRSA, in raw milk and dairy products, raises a serious public health concern, because these strains may cause food poisoning outbreaks, be disseminated to the population, or both.

Diversity of Staphylococcus aureus clones in wild mammals in Aragon, Spain, with detection of MRSA ST130-mecC in wild rabbits.

AIMS: To determine the Staphylococcus aureus carriage rate in wild mammals in Aragon, northern Spain, to analyse their antimicrobial resistance phenotype/genotype and to characterize the recovered isolates. METHODS AND RESULTS: Nasal and rectal swabs of 103 mammals were collected in Aragón during the period 2012-2015. Antimicrobial susceptibility, the presence of antimicrobial resistance genes and virulence factors were investigated. Molecular characterization was carried out by spa, MLST, agr and SCCmec. Staphylococcus aureus were recovered from 23 animals (22%). Four of the 23 S. aureus were methicillin-resistant S. aureus (MRSA). Three MRSA were mecC-positive and were isolated from European rabbits and were typed as t843 (ascribed to CC130). The remaining MRSA was a mecA-carrying isolate from European hedgehog, typed as ST1-t386-SCCmecIVa-agrIII and it harboured the blaZ, erm(C), ant(6)-Ia and aph(3´)-IIIa resistance genes. A high diversity of spa-types was detected among the 19 methicillin-susceptible S. aureus isolates, which showed high susceptibility to the antimicrobials tested. The tst gene and different combinations of staphylococcal enterotoxins were found. CONCLUSIONS: Staphylococcus aureus were detected in nasal and rectal samples of wild mammals. Wild rabbits could be a reservoir of mecC-MRSA. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides information on the presence and characteristics of S. aureus from mammals in a defined geographic region in Spain.