Objectives: Skin and soft tissue infections (SSTIs) are a serious health issue for military personnel. Of particular importance are those caused by MRSA and PVL-positive S. aureus (PVL-SA), as they have been associated with outbreaks of SSTIs. A prospective observational study was conducted in Royal Marines recruits to investigate the prevalence of PVL-SA carriage and any association with SSTIs.
Methods: 1,012 RM recruits were followed through a 32-week training programme, with nose and throat swabs obtained at weeks 1, 6, 15 and 32. S. aureus isolates were characterised by antibiotic susceptibility testing, spa typing, presence of mecA/C and PVL genes. Retrospective review of the clinical notes for SSTI acquisition was conducted.
Results: S. aureus colonisation decreased from week-1 to week-32 (41% to 26%, p<0.0001). Of 1,168 S. aureus isolates, 3/1168 (0.3%) were MRSA and 10/1168 (0.9%) PVL-positive (all MSSA) and 169/1168 (14.5%) were resistant to clindamycin. Isolates showed genetic diversity with 238 different spa types associated with 25 MLST clonal complexes. SSTIs were seen in 35% (351/989) of recruits with 3 training days lost per recruit. SSTI acquisition rate was reduced amongst persistent carriers (p<0.0283).
Conclusions: Nose and throat carriage of MRSA and PVL-SA was low amongst recruits, despite a high incidence of SSTIs being reported particularly cellulitis. Carriage strains were predominantly MSSA with a marked diversity of genotypes. Persistent nose and/or throat carriage was not associated with SSTI acquisition. Putative person-to-person transmission within troops was identified based on spa typing requiring further research to confirm and explore potential transmission routes.