Carbapenem Resistant Characteristics And Environmental Impact Factors Of Clinical Isolated Enterobacteriaceae

In the past decade,the carbapenemase-producing Enterobacteriaceae(CPE)have been reported worldwide.Emergence of carbapenemase-producing strains among Enterobacteriaceae has been a challenge for treatment of clinical infection and disease controlling due to rapid spreading of anti-biotic resistante bacteria.The present study was conducted to illustrate the characteristics of carbapenemase-producing Enterobacteriaceae in Yunnan province,a frontier province in southwest China.Simultaneously,risk factors of infection caused by CPE and homology of CPE were analyzed.From 1999 to 2013,a total of 11887 Enterobacteriaceae strains were isolated from the patients hospilized in the First People's Hospital of Yunnan province.The collected patients' information and antibiotic resistence of these strains were restrospectively studied.It was showed that ESBL-positive rates of isolated Enterobacteriaceae strains were stably high during past 15 years.But,the antibiotic resistant rates of them were increased rapaidly,particularly of the ESBL-producing strains.The appearance of carbapenem-resistant Enterobacteriaceae(CRE)has provide a caution for antibiotic using.Furthermore.a total of 144 suscepted carbapenem Enterobacteriaceae were collected from patients at 4 representative hospital in Yunnan province.Modified Hodge test and minimum inhibitory concentrations(MICs)for antimicrobial agents were determined according to the guidelines of the Clinical and Laboratory Standards Institute(CLSI).Resistant genes were detected by using PCR.Among collected 144 non-susceptible to carbapenem Enterobacteriaceae.carbapenemase genes were detected in 113 strains(78.5%,113/144).The blaKPC-2(99/113.87.6%)was the most common carbapenemase gene and Klebsiella pneumoniae(100/113,88.5%)was the most common species of CPE.Moreover.BlaNDM-1(11/113,9.7%),blaIMP-4(10/113.8.8%).and blaIMP-1(1/113,0.9%)genes were also detected.The extended-spectrum ?-lactamases(ESBL)is common in CPEs,SHV-and CTX-M-were the predominant type.SDS-PAGE showed that loss of porins was contribute to the high MIC values.There are 35 Enlerobacteriaceae strains isolated from neonatal intensive care unit(NICU)harboring blaIMP-4 gene were confirmed by using PCR.The homology was analyzed by enterobacterial repetitive intergenic consensus PCR(ERIC-PCR).ERIC-PCR indicated that CPE strains were genetically related.Clinical informations were collected to analysis the risk factors for CPE infection and colonization in neonates.Exposure to antibiotics,invasive procedure,and basic disease were associated with CPE infection.The characteristics of carbapenem-resistant Klebsiella pneumoniae recovered from an outbreak that affected 17 neonatal patients in NICU were analyzed.Eighteen highly carbapenem-resistant Klebsiella pneumoniae were isolated from patients in NICU and one carbapenem-resistant K.pneumoniae isolate was detected in incubator water.All these isolates harbored blaNDM-1.Moreover,other resistance genes,viz.,blaIMP-4,blaSHV-1,blaTEM-1,blaCTX-M-15,qnrSl,qnrB4,and aacA4 were detected.The blaNDM-1 gene was located on a ca.50kb IncFI type plasmid.PFGE analysis showed that NDM-1-producing K.pneumoniae were clonally related and MLST assigned them to sequence type 105.Overall prevalence of ESBL production among clinical isolates of Enterobacteriaceae was high,which indicated that the drug resistant situation of Enterobacteriaceae isolates is very serious.Producing carbapenemases,especially KPC-2,was the main mechanism casuing carbapenems-resistant among Enterobacteriaceae in Yunnan province.The carbapenemase genes in CPE strains isolated from neonatal patients were mainly blaIMP-4 and blaNDM-1,.which were different from adult patients(bla KPC-2).Risk factors for CPE infection were multifactorial.NDM-1 producing strains present in the hospital environment pose a potential risk and the incubator water may act as a diffusion reservoir of NDM-1-producing bacteria.To avoid the occurrence of resistance,it is critically important to monitor the drug resistance and prescribe antibacterial agents rationally,meanwhile effective implementation of infection control measures should be taken to control the spread of resistant strains.