Analysis of the joint presence of clinically relevant drug resistance markers in Pseudomonas aeruginosa.

ELENA ALAN; CEJAS DANIELA; MARINO R; QUINTEROS MIRTA; GUTKIND GABRIEL; DI CONZA JOSÉ; RADICE MARCELA

New Orleans

Congreso; ASM MICROBE 2017; 2017

American Society for Microbiology

Background: Pseudomonas aeruginosa is one of the leading gram negative bacteria associated with hospital acquired infections, particularly in compromised patients. It is naturally resistant to a wide set of antimicrobials agents, thus narrowing down the therapeutic options to carbapenems, fluoroquinolones, colistin and to a lesser extent aminoglycosides. Reports of plasmid acquired resistance markers are abundant in this species, implying almost exclusively carbapenems and aminoglycosides. Our goal was to investigate the joint presence of different resistance markers in carbapenem resistance P. aeruginosa. Methods: Thirty-eight P. aeruginosa isolates recovered during 2012 in a health centre in Buenos Aires were included. Susceptibility tests were performed according to CLSI and the presence of metallo-β-lactamases (MBLs) was investigated by double disk synergy test using EDTA. Plasmid DNA was extracted using the Kado and Liu method, and subsequently used as a template for PCR analysis and electroporation assays. MBL, PMQR and mcr-1 coding genes were screened by PCR and amplicons were sequenced. Results: Twenty-six isolates displayed carbapenem resistance and 14 of them rendered positive results when the phenotypic MBL test was carried out. Plasmid MBLs coding genes were identified in all these isolates corresponding to: blaVIM-2 (5/14), blaVIM-11 (2/14), blaVIM-like (5/14) and blaIMP-13 (2/14). Six out of 12 VIM genes were transferred by electroporation. One of the blaVIM isolates also harboured qnrS1 while the others tested negative for any of the PMQR determinants. No association between qnrS1 determinant and class 1 integron platform could be found. Finally, no mcr-1 determinant was detected. Conclusion: The MBL genes detected in this work correspond with the ones previously reported in our country; nevertheless, this is to date one of the few worldwide reports of P. aeruginosa carrying plasmid MBL genes and a PMQR determinant, thus restricting the antibiotic alternatives. Although colistin appears to remain a useful drug against this pathogen, the existence of mcr plus the ability of this microorganism to acquire plasmid resistance mechanisms is of concern.