ABSTRACT
Objective To investigate the resistance mechanism of a carbapenems-resistant Leclercia adcarboxglata.Methods The species was identified by the automatic microbial analyzer,matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA sequence analysis.The conventional drug susceptibility test was detected with automatic microbial analyzer,and the minimum inhibitory concentration (MIC) for imipenem was examined by E-test.The phenotypes of carbapenemase were detected by modified carbapenem inactivation method (mCIM) and the genotypes of resistance genes were detected by polymerase chain reaction (PCR) and DNA sequencing.The characteristics of the carried plasmid were analyzed by conjugation test and S1pulsed-field gel electrophoresis (S1-PFGE).Results The clinical isolates of Leclercia adcarboxglata were resistant to imipenem,other beta-lactam antibiotics(except aztreonam) and aminoglycosides,but sensitive to quinolones and sulfonamides.The conjugation test resulted in a drug-resistance spectrum of the receptor strain E.coli J53 similar to Leclercia adcarboxglata bacteria.The phenotype of carbapenemase was positive.PCR amplification and sequencing analysis showed that blaNDM-1,blaTEM and aac (6')-Ib were detectable in the isolates simultaneously,while the conjugon only carried blaNDM-1.S1-PFGE revealed that Leclercia adcarboxglata carried 3 plasmids.Conclusion The carbapenems resistance of Leclercia adcarboxglata may contribute to carrying blaNDM-1 gene which may exist in an around 100 kb plasmid transmitted with conjugation.
ABSTRACT
We investigated the cause of a leukemia patient induced by infect in a strain of Klebsiella oxytoca with hypermucoviscosity (HMV) phenotype.Identification and drug susceptibility of the isolate were carried out with VITEK-2 compact system.HMV phenotype was detected by string-test.The major high virulence capsular serotypes (K1,K2,K5,K20,K54 and K57) and virulence factors (rmpA,wcaG,allS,kfu,aerobactin,fimH,uge,wabG and cf29a) were detected by polymerase chain reaction and DNA sequencing.Molecular typing was performed by multilocus sequence typing (MLST).Results showed that the isolates of blood and lung tissue were Klebsiella oxytoca belonged to ST 19,which were sensitive to the antibiotics used in test,expressing the HMV phenotype.The virulence gene wcaG was found,while other virulence genes and the major high virulence capsular serotypes were negative.It indicates that ST19 Klebsiella oxytoca with wcaG virulence gene is the main reason causing leukemic patient death.