INVESTIGADORES
MOLLERACH Marta Eugenia
congresos y reuniones científicas
Título:
Increase in IS256 Transposition in Different S. aureus Lineages After Antibiotic Selective Pressure
Autor/es:
DI GREGORIO S; HERRERA M; FERNÁNDEZ S; DI CONZA J; FAMIGLIETTI A; MOLLERACH M
Lugar:
Boston
Reunión:
Congreso; ASM Microbe 2016; 2016
Institución organizadora:
American Society for Microbiology
Resumen:
Background: In S. aureus, transposition of IS256 has been described to play an important role in biofilm formation and antibiotic resistance. Previously, we reported an augment in IS256 transposition associated with the selection of hVISA/VISA strains, both in vivo and in vitro, indicating that VAN pressure could enhance IS256 transposition, and eventually the loss of agr function. In this study we aim to characterize the effect of antibiotic selective pressure in IS256 transposition of S. aureus isolates belonging to different lineages.Methods: Mutant strains were independently selected on increasing concentrations of vancomycin (ST8, ST100) and tigecycline (ST5, ST239). Isolates were genotypically characterized by PFGE, MLST, spa, SCCmec, agr, and southern hybridization using IS256 andagrAC specific probes. The agr locus functionality was determined by delta-heamolysis assay. The sigB and rsbU regulatory genes were mapped by PCR. Additionally, the transcription of IS256 transposase (tnp) gene was evaluated by RTqPCR for ST5 and ST239 strains. Data was expressed as normalized relative quantities (NRQ) using gyrB and pta as reference genes. All experiments were performed by triplicate. Statistical analysis of the data was accomplished using Student t test (alfa=0.05).Results: Isogenicity between mutant and parental strains was confirmed by PFGE. An increase in IS256 copies was demonstrated in mutants selected with vancomycin (MRSA-ST100-IVnv-t002-agrII, and MSSA-ST8-t008-agrI), and tigecycline (MRSA-ST239-III-t654-agrI) by southern blot hybridization. No copy of IS256 was inserted into sigB and rsbU genes. NRQ values of tnp gene were significantly higher in ST239 mutant strain when compared to parental strain (p