Frequent dissemination and carriage of an SCCmec-mecC hybrid in methicillin-resistant Mammaliicoccus sciuri in farm animals from Tunisia.

OBJECTIVES: In this study, we aimed to assess the extent of dissemination of methicillin-resistant Mammaliicoccus sciuri in animal farms in Tunisia and evaluate the distribution of virulence and methicillin resistance genes in the M. sciuri population. METHODS: Staphylococci and mammaliicocci isolated from unhealthy animals and healthy humans from adjacent farms in Tunisia were characterized for antimicrobial susceptibility, biofilm formation, agglutination, and hemolysis abilities. Mammaliicoccus sciuri relatedness and content in antibiotic resistance and virulence genes were analyzed by whole-genome sequencing (WGS). RESULTS: Mammaliicoccus sciuri was the most prevalent species (46.2%), showing the highest resistance rates to fusidic acid (94.6%), oxacillin (73%), penicillin (40.5%), clindamycin (37%), ciprofloxacin (27%), and cefoxitin (24.3%). Some isolates carried genes encoding resistance to nine different antibiotic classes. mecA was found in 35% of M. sciuri and mecC in 16.2%. All isolates carrying mecC were of S. sciuri subspecies carnaticus and carried the hybrid element SCCmec-mecC. Mammaliicoccus sciuri were able to produce strong biofilm (27%) and have clumping ability (16%). Additionally, they carried genes for capsule production (cap8, 100%), iron-regulated surface determinants (isdE, 24%; isdG, 3%), and virulence regulation (clpC and clpP, 100%). Single nucleotide polymorphisms (SNPs) analysis showed that 17 M. sciuri cross-transmission events probably occurred between different animal species and farms. Moreover, SCCmec was estimated to have been acquired five times by S. sciuri subsp. carnaticus. CONCLUSION: Multidrug resistant and pathogenic M. sciuri were frequently disseminated between different animal species within the farm environment. mecA and mecC can be disseminated by both frequent acquisition of the SCCmec element and clonal dissemination.

Prevalence of meticillin-resistant and -susceptible coagulase-negative staphylococci with the first detection of the mecC gene among cows, humans and manure in Tunisia.

In Europe, a novel mecA homologue - mecC (formerly mecALGA251) - has emerged recently in staphylococci from animals, humans and the environment. This paper reports the first occurrence of the mecC gene in Staphylococcus sciuri from cows and manure in Tunisia and Africa. Forty-nine coagulase-negative staphylococci (CNS) were isolated from the milk of cows with mastitis (n=20), manure (n=20) and human nares (n=9), including 16 Staphylococcus equoruim (32.6%), 12 S. xylosus (24.5%), 12 S. sciuri (24.5%), two S. saprophyticus (4.1%), two S. haemolyticus (4.1%), two S. lentus (4.1%), two S. vitulinus (4.1%) and one S. cohnii (2%). CNS from the three origins carried various resistance genes [mecA, blaZ, tet(K), erm(A), erm(B), msr(A)], suggesting an ongoing genetic exchange among CNS from the three niches. The mecA gene was detected in CNS (n=11) recovered from cows, manure and humans, whereas the mecC gene (n=3) was only detected in CNS from cows and manure. Various staphylococcal cassette chromosome mec (SCCmec) - SCCmec type I (n=1), II (n=3), IV (n=2), V/VII (n=2) and untypeable (n=3) - and diverse pulsed-field gel electrophoresis (PFGE) patterns were observed in mecA-positive CNS. Otherwise, similar SCCmec types and PFGE patterns were found in meticillin-resistant CNS within different farms and origins, showing the potential of SCCmec interspecies exchange and circulation of the same clones of meticillin-resistant CNS in the human-animal-environment interface. This study provides baseline data to support clonal dissemination of CNS between cows, humans and manure, and indicates the possible transmission of the mecC gene to humans in contact with cows and manure.