Analysis for biofilm, quorum sensing related genes and drug resistance in clinical isolates of Pseudomonas aeruginosa / 临床检验杂志

ABSTRACT

Objective To study the relationship between biofilm-forming ability,distribution of quorum sensing related genes and antibiotic resistance in clinical isolates of Pseudomonas aeruginosa.Methods The biofilm-forming ability of 94 clinical isolates was analyzed semi-quantitatively by crystal violet staining.The antibiotic resistance of the isolates was determined by K-B method.Quorum sensing related genes,lasI,lasR,rhlR and rhlI,were detected by PCR.The diffe,rences of drug resistance of Pseudomonas aeruginosa with different biofilm-forming ability and the effects of quorum sensing related genes on biofilm-forming ability were analyzed.Results Of the 94 isolates,89(94.7％) showed biofilm-forming ability.The 89 isolates consisted of 22(23.4％) isolates with weakly positive biofilm-forming ability,44 (46.8 ％) with positive biofilm-forming ability and 23 (24.5 ％) with strongly positive biofilm-forming ability.The strains of Pseudomonas aeruginosa with different biofilm-forming ability showed different drug resistance rates to amikacin,tobramycin and gentamicin (P ＜ 0.05).The drug resistance rate of the strains with strong positive biofilm-forming ability to amikacin was higher than that of the strains with positive and weakly positive biofilm-forming ability(P ＜ 0.05),and the drug resistance rates to tobramycin and gentamicin were higher than those of the strains with weakly positive biofilm-forming ability(P ＜ 0.05).Of the 94 isolates,91 strains carried lasI,lasR,rhlI and rhlR gene and 2 strains only lost lasR gene,and 1 strain lost all the 4 genes.The strains with only lasR gene deficiency or all the lasI,lasR,rhlI and rhlR gene deficiencies showed negative biofilm-forming ability,and were sensitive to conventional antimicrobial agents.Conclusion Most of the clinical isolates of Pseudomonas aeruginosa in this study showed strong ability of biofilm-forming ability which may correlate positively to partial antibiotic resistance.The quorum sensing related genes may affect biofilm formation of Pseudomonas aeruginosa.