Molecular characterization of Staphylococcus aureus isolated from humans related to a livestock farm in Spain, with detection of MRSA-CC130 carrying mecC gene: A zoonotic case?

Abstract

Objectives: To conduct a study of Staphylococcus aureus carriage in members of a livestock-farmer's family with different degrees of animal contact, and to characterize the recovered isolates.

Methods: Nasal samples from 11 members of the family were taken in three sampling periods (every six months) (n=31), and 9 skin samples from superficial lesions were also obtained in 5 of them. Samples were analyzed for S. aureus susceptible (MSSA) and resistant to methicillin (MRSA). S. aureus isolates were tested for antibiotic-resistance phenotype and genotype and for the detection of virulence and IEC-system genes. Molecular typing of isolates was also performed (spa- and multilocus-sequence typing).

Results: Eighteen S. aureus isolates were recovered (1 MRSA and 17 MSSA) in the 40 samples analyzed. S. aureus was detected in nasal and skin samples of 7/11 and 4/5 of tested humans, respectively. The MRSA strain was detected in the skin lesion of a farmer with high animal contact, and carried the mecC gene, and was typed as ST130-CC130-t843. The 17 MSSA isolates were ascribed to 9 different spa-types and sequence types included in the clonal complexes CC22, CC30, CC45, CC121, and in the livestock-associated lineages CC9 and CC133. Six strains harbored eta or tsst-1 genes. Three of 18 strains lacked the immune-evasion-cluster (IEC) genes (MRSA-ST130, MSSA-ST1333, and MSSA-ST133), and the remaining isolates were ascribed to IEC type-A or -B.

Conclusions: Animal-associated S. aureus lineages were detected in samples of the farmer's family, highlighting the detection of MSSA-CC133 and mecC-MRSA-ST130.

Keywords: CC130; CC133; Farmers; Granjeros; S. aureus; mecC.