Virulence, antimicrobial resistance and disinfectant tolerance in pseudomonas aeruginosa strains

In this study, it was aimed to investigate common bacterial virulence factors of clonally unrelated Pseudomonas aeruginosa isolates, to detect disinfectant and antimicrobial susceptibilities, and the effects of disinfectant/antimicrobials on biofilm alone and in combination on in vitro conditions. Antimicrobial suscebptibilities of P. aeruginosa strains which isolated in Ege University Hospital, Medical Microbiology, Bacteriology Laboratory was determined by disc diffusion method and epidemiological relations among the strains was investigated by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC–PCR). Quorum sensing (QS) genes (lasI, lasR, rhIL, rhlR) of clonally unrelated P. aeruginosa isolates were investigated by PCR and virulence factors (DNase, elastase, protease, lipase, siderophore, pigment and biofilm production and twitching motility) were also determined by phenotypic methods. The susceptibilities of disinfectants (polyhexanide (PHMB), 2% gluteraldehyde (2% GLT), chlorhexidine (CHX), quarternary ammonium compounds (QAC)) and the antimicrobial-ciprofloxacin (CIP) were assessed using microdilution method according to CLSI, effects of disinfectants and antibiotic alone and in combinations on biofilm were investigated by crystal violet method. . The efflux pump (EP) genes (mexR, nfxB) were determined by the PCR and changes of ciprofloxacin MIC levels in the presence of the EP inhibitors (EPIs) phenylalanine-arginine-beta napthylamide (PAβN) and 1-(1-naphthylmethyl) piperazine (NMP) were determined by using microdilution method. The relationship between phenotypic and genotypic properties was investigated by Fisher's chi-square exact method. Eighty three P. aeruginosa strains were evaluated by ERIC-PZR as 19 clonally unrelated strains. According to disc diffusion and microdilution methods, 10 of the clonally unrelated strains were found to be resistant to CIP, two of them were intermediate and seven were susceptible. In the clonally unrelated strains, the lasI gene was found to be positive 89,5% and the lasR gene 94,7% positive. It was determined that the rhlR gene had a percentage of 68,4% when all the strains were have rhlI gene. Elastase and siderophor production of virulence factors were found in all of isolates. Pigment production was 84,2%, twitching motility was 79%, lipase production was 74% and protease production was 26,3%. No DNase was detected in any of the strains. Nine of the strains showed strong biofilm production capacity and CHX was identified as the disinfectant with the lowest MIC value on the isolates. When the effects of disinfectants and CIP combinations were examined in strong biofilm-producing strains, it was determined that CHX-CIP was the most effective combination for biofilm inhibition. In addition, EP genes (mexR, nfxB) were detected in all strains except one. 10 CIP-resistant and two CIP-intermediate strains' MIC values were determined by microdilution method with EPI PAβN, and in these strains CIP MIC values were found to decrease four times and over. No decrease was determined in CIP MIC values in the presence of NMP. According to the results of the Fisher's chi-square exact method, the relationship between the phenotypic and genotypic properties was not statistically significant (p>0.05). With the data obtained from this thesis, we have been informed about which virulence genes are responsible for nosocomial Pseudomonas infections seen in our hospital, tolerance to disinfectants and antimicrobial resistance. It has also been suggested that combinations of antibiotics and disinfectants in P. aeruginosa strains with multiple drug resistance may have information about the synergistic effects of biofilm formation and mature biofilm, thus suggesting options for treatment options