92 Chapter 5 Virulence factors An overview of the distribution of virulence genes among the patients with eradication failure and patients with successful decolonization is presented in Table 4. No associations were found between virulence genes and failure of eradication. Remarkably, PVL (lukF_PV and lukS_PV) was found more often in patients with successful decolonization compared to the patients with eradication failure, although non-significant (30% vs 17%, P =0.48). The genes lukF_PV and lukS_PV and spIE were significantly associated with an MRSA infection (P <0.05). The genes aur, hlgABC, icaACD, setB, setC, hlI, hlII, arcc, aroe, glpf, gmk, pta, tpi, yqil, isaB, lukX, lukY, and ebpS were present in all isolates and were therefore excluded from the analysis. The genes arc, edinABC, etABD, seb, sec, and sed were only sporadically present and were therefore excluded from the analysis as well. Discussion In this study, we explored associations between MRSA isolate characteristics, genetic determinants, and decolonization outcomes in a Dutch population of MRSA carriers in a tertiary hospital. We found an association of eradication failure with carriage of ciprofloxacin-resistant healthcare-associated lineages, whereas livestock-associated MRSA lineage ST398 and the majority of community-associated MRSA lineages ST6-t304 and ST8-t008 were associated with successful eradication treatment or spontaneous clearance. The failure rate in eradication treatment of complex MRSA carriers was higher compared to previous reports in Dutch studies [5, 7]. Our study was conducted in the outpatient clinic of a tertiary hospital, with consequently a more than average representation of healthcare workers or patients with an extensive history of hospitalizations. Such patients mainly carry healthcare-associated MRSAs, that are adapted to survive under harsh nosocomial conditions and antibiotic exposure. In our study, we found an association between ciprofloxacin resistance and failure in eradication treatment. Remarkably, none of the patients had been treated with ciprofloxacin. The ciprofloxacin-resistant MRSAs in our study belonged to various lineages, including five isolates of the healthcare-associated ST5 lineage with single amino acid substitution in GrlA S80F. The mutation in this healthcare-associated lineage, and its association with fluoroquinolone resistance and the presence of virulence genes as enterotoxins, β-hemolysin converting phage, and leucocidins has been described previously [21].
RkJQdWJsaXNoZXIy MTk4NDMw