Qingdao Drug Resistance Of Pseudomonas Aeruginosa And Metal Enzyme, Outer Membrane Porin OprD2 Gene Testing

Objective:To learn out the antibiotics resistant characteristics of Pseudomonas aeruginosa isolates in Qingdao region and detect the distribution of metallo-β-lactamase (MBL)and the deletion of outer membrane protein oprD2gene, so as to provide experimental basis to guide the clinical application of antimicrobial agents.Methods:From January2012to January2013,180non-duplicated clinical isolates of Pseudomonas aeruginosa were collected from three tertiary hospitals in Qingdao. All strains were identified by VITEK-2; K-B method was used to do drug susceptibility test; E-test(IPM/EDTA) method was used to detect MBL phenotype; PCR was applied to detect MBL genes (IMP-1、IMP-2、VIM-1、VIM-2、GIM、SPM、SIM、NDM)and outer membrane protein oprD2gene.Results:①The specimens were mainly isolated from respiratory tract secretion, accounting for81.11%(146/180).②The first detection rate of Pseudomonas aeruginosa is ICU ward and the second is respiratory ward, which accounted for50.56%(91/180) and28.89%(52/180), respectively.③Among the180isolates collected, the detection rate of multi-drug resistant Pseudomonas aeruginos and Pan-drug resistant Pseudomonas aeruginos was33.89%(61/180) and15.56%(28/180).The resistant rates to aminoglycoside antibiotics such as Gentamicin. Todramycin. Amikacin was60.00%、61.11%、40.00%; the resistance rate to quinolones such as Ciprofloxacin、Levofloxacin was44.44%.53.33%; the resistance rate to sulfa drugs (sulfamethoxazole) was98.89%;the resistance rate to Penicillins (Piperacillin) was85.56%; the resistance rate to (3-lactam/p-lactamase inhibitor complexes such as Piperacillin/tazobactam, Cefoperazone/sulbactam was63.89%and28.33%; the resistance rate to Cephalosporin drugs:Cefazolin. Cefuroxime. Cefotaxime,、Cefoperazone、Ceftriaxone、Ceftazidime、Cefepime was84.44%、83.33%、81.11%、72.22%、70.00%、49.44%and50.56%, respectively; the resistance rate to Monocyclic beta lactam drugs (Aztreonam) was52.78%; the resistance rate to carbapenem antibiotics such as Imipenem. Meropenem was38.33%、33.89%; the sensitive rate to Polymyxin B was100%.④The isolation rate of Imipenem resistant Pseudomonas aeruginosa (IRPA) was38.3%(69/180). Among the69IRPA strains,88.41%(61/69) strains were multidrug resistant strains and40.58%(28/69) strains were pan drug resistant strains.The resistant rates to16of20drugs were higer than60%in IRPA, only the sensitive rates to Ciprofloxacin, Amikacin,Cefoperazone/sulbactam, Polymyxin B were higher, which was47.22%、50.72%、62.32%and100%, respectively. The difference of the resistance rates to17antibiotics between IRPA strains and ISPA strains were statistically significant (P<0.05).⑤13strains of imipenem resistance group screened by E-test method were shown to be positive for MBL,the detection rate of which was18.84%(13/69),while all strains of imipenem sensitive group were shown to be negative for MBL, the detection rate of which was0.00%(0/111).11strains of imipenem resistance group amplified by PCR were shown to be positive for MBL genes, the detection rate of which was15.94%(11/69).4strains detected IMP-1gene,7strains detected VIM-2gene. IMP-2、VIM-1、GIM、SPM、SIM、NDM genes were not found. while all kinds of MBL genes were not found in all strains of Imipenem resistance group. Comparing the positive rate of phenotype and genotype of MBL in two groups, detection rate of resistance group was significantly higher than that of sensitive group (P<0.05).⑥53strains of Imipenem resistance group were lack of outer membrane protein oprD2gene, the loss rate of which was76.81%(53/69); while12strains of Imipenem resistance group were lack of outer membrane protein oprD2gene,,the loss rate of which was10.81%(12/111).The loss rate of resistance group was significantly higher than that of sensitive group (P<0.05).Conclusions:①The infection caused by Pseudomonas aeruginos is mainly the respiratory system in this region.②Intensive Care Unit is the high incidence area of Pseudomonas aeruginosa infection in this region.③The resistance of Pseudomonas aeruginos is serious in this region, especially Imipenem-resistant Pseudomonas aeruginosa, which shows different degrees of resistance to the penicillins, cephalosporin drugs, carbapenems and other antimicrobials commonly used in clinical and only sensitive to Ciprofloxacin, Amikacin,Cefoperazone/sulbactam, Polymyxin B. At present fluoroquinolones(Ciprofloxacin)、aminoglycosides(Amikacin) and inhibitors of β-lactamase (Cefoperazone/sulbactam) were the first choice to the treatment of infection caused by Pseudomonas aeruginos. If conditions permit, Polymyxin can be selected to treat infections, but the patient’s kidney function must be closely monitored.④The gene existence of metallo-β-lactamase and metallo-β-lactamase producing is one of the main resistance mechanism of Pseudomonas aeruginos to Imipenem, the major genotypes are IMP-1and VIM-2.⑤The loss rate of outer membrane protein oprD2gene is very high, indicating the loss or reduction of outer membrane protein oprD2is the main resistance mechanism of Pseudomonas aeruginos to Imipenem in this region.