Surveillance Of Antibiotic Resistance And Study On Genotype Of Klebsiella Pneumoniae Producing Metallo Lactamases

PART Idistribution and antibiotic resistance of855isolates of KlebsiellapneumoniaeObjective To investigate the distribution and antibioticresistance of Klebsiella pneumoniae isolated from our hospital during theperiod of Jan2008-Dec2011.Methods All isolates were identified from ATB analysis system andcharacterized by Kirby Bauer antibiotic sensitivity testing and a doubledisk synergy testing for detection of extend-spectrum β-lactamase (ESBLs).Date were analyzed by WHONET5.5and SPSS17.0softwares.Results The majority of855strains isolated were from ICU (29.3%;with higher resistance rates than non-ICU isolates), followed by respiratorydepartment (17.2%) and neurosurgery department (15.5%). The K.pneumonia-positive specimens were mostly derived from sputum (68.9%),urine (8.1%), and secretion (6.2%). The rates of resistance to differentantibiotic agents were as follows:96.9%for ampicillin,48.0%for piperacillin, and34.3%-51.1%for the first to fourth-generationcephalosporins except for cefoxitin (17.2%), less than12.0%forpiperacillin/tazobactam, cefoperazone/sulbactam or amikacin,6.3%forimipenem,3.6%for meropenem, and4.2%for ertapenem. Compared withthose in2008-2010, the rates of resistance to carbapenems in2011hassignificantly decreased, especially to imipenem. ESBLs-producing K.Pneumoniae was detected in35.2%of the isolates. The rates of resistanceto most antibiotics in ESBL-positive K.pneumoniae were higher thanESBL-negative counterparts.Conclusion Clinical isolates of K.pneumoniae have displayed highdegrees of resistance (including multidrug resistance) to various antibioticagents. Thus, the hospitals should strengthen the monitoring programs andtake intervention measures in controlling resistance development andspread, especially in ICU. Although carbapenems, pipercillin/tazobactam,cefoperazone/sulbactam and amikacin can be chosen for treatment of K.pneumoniae infections, the development of resistance to these agentsshould be considered. PART IIStudy on homology and integron of Klebsiella pneumoniae producingmetallo-β-lactamasesObjective To investigate the antibiotic resistance, homology,genotypes and integron of Klebsiella pneumoniae producingmetallo-β-lactamases isolated from our hospital during the period of Jan2010-Dec2010.Methods16carbapenem-nonsensitive K.pneumoniae werecollected from clinical specimens of patients in our hospital; EDTAdouble-disk synergy test were used to screen metallo-β-lactamase(MBL).PCR was used to identify metallo-β-lactamase genotypes and intergrongenes, and sequenceing was performed. The homology of genomic DNA ofthese strains was analysed by ERIC-PCR. The sensitivity to antibiotics wasdetected by agar dilution method.Results From a total of16carbapenem-nonsensitive isolates wereidentified and5of which were positive by EDTA double-disk synergy test,and4of which produced IMP-8-type metallo-β-lactamase, IMP-8MBLfrom3strains was located in the class I integron; While no class II, classIII integron and blaVIM, blaGIM, blaSIM, blaSPM, blaNDMwas detected in thesestrains.4isolates producing IMP-8MBL were classified into twogenotypes by ERIC, of which3strains isolated from sputum of the patientsin the ICU of Respiratory were the same type A,1strains was another typeB. Antibiotic susceptibility data showed that all3strains of type A were resistant to penicillins, cephalosporins antibiotic, aztreonam, ciprofloxacin,and K2isolate was intermediary to imipenem and meropenem, susceptibleto amikacin; K1and K4were resistant to imipenem, meropenem andamikacin. K3isolate of type B was resistant to β--lactam antibiotics,except for aztreonam, but susceptible to amikacin and ciprofloxacin.Conclusion IMP-8metallo-β-lactamase producing K.pneumoniaeclone is prevalent in the ICU of Respiratory and the resistant gene waslocated in the class I integron, health care workers should emphasis on thisphenomenon and take effective measures.