Auxotrophic mutant of Staphylococcus aureus as a potential immunoprophylactic tool in the nasal carriage

BARBAGELATA MS, ALVAREZ LP, GORDIOLA ML, CERQUETTI MC, SORDELLI DO AND BUZZOLA FR.

San Miguel de Tucumán, Argentina

Congreso; 45th Annual Meeting Argentine Society for Biochemistry and Molecular Biology Research; 2009

S. aureus nasal carriage is a risk factor for infection in humans, particularly in the hospital environment. The active colonization with a strain of S. aureus which possess minimal pathogenic properties is able to prevent colonization by more virulent strains. In this work auxotophic mutant of S. aureus Newman strain was constructed by genetic replace. The selected working mutant was called NK41 and showed to be attenuated and stable. In a murine model, previous NK41 nasal colonization significantly reduces the implantation of the most prevalent clones of S. aureus in Argentina [pediatric (Hde288) and cordobes (HU-71) clones]. In the same way, NK41 was evaluated in a human nasal in vitro environment on A549 cell line. The mutant showed the same level of internalization that its parental Newman strain. However, inside the cells, the effect of NK41 differs from Newman causing not cellular damage and inability to trigger the production of the pro-inflammatory interleukins IL-6 and IL-8. Moreover, NK41 was able to interfere the invasion on A549 cell line of Newman, Hde288 and HU-71 strains of S. aureus. These results encourage the possibility of local topical applications with the mutant NK41 to avoid, through bacterial interference, the entrance of other pathogenic strains of S. aureus in hospitalized patients, without affect the nasal microenvironment.