Objective: To investigate the drug-resistant gene characteristics and core genome characteristics of carbapenem-resistant Enterobacter cloacae (CR-ECL) in rural residents of Weifang City, Shandong Province. Methods: Fecal samples were collected from rural community residents in Weifang City, Shandong Province in 2017. Drug-resistant strains were screened using a carbapenem-resistant enterobacter chromogenic medium. CR-ECL positive strains were acquired via Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry(MALDI-TOFMS) analysis. The antibiotic resistance phenotype of CR-ECL was determined using a microbroth dilution assay. Whole genome sequencing (WGS) and analysis were conducted, along with an examination of the immediate vicinity of the bla_NDM gene and phylogenetic analysis of the strains. Results: A total of 628 fecal samples were collected and tested, of which 6 were CR-ECL positive (detection rate 0.96%), all exhibiting multiple drug resistance (MDR) phenotypes. Six CR-ECL strains had four MLST genotypes (ST), all of which carried multiple drug resistance genes (bla_NDM-1, bla_NDM-5, etc.) and virulence genes (acrA, acrB, entB, fepC, etc.). There were mobile genetic elements ISAba125, TN3-IS3000, TN3 and IS5 in the genetic environment surrounding the bla_NDM gene. The phylogenetic tree showed that the multi-locus sequence typing of the core genome (cgMLST) was consistent with the single nucleotide polymorphism (SNPs) results. The cgMLST results showed that the allele differences between strains 2BC0101B and 2BC0251B, 2BG0561B and 2BI0221B were 2 and 1, respectively. The SNPs results showed that the above two pairs of bacteria also clustered together. It was found that the strains of chicken fecal samples in the National Center for Biotechnology Information (NCBI) database were located in the center of the evolutionary tree, and the local sequences could be traced back to American human sequences. Conclusion: Multidrug-resistant CR-ECL is detected in rural community residents in Weifang City, Shandong Province.
Humans ; Anti-Bacterial Agents/therapeutic use* ; Enterobacter cloacae/genetics* ; Multilocus Sequence Typing ; beta-Lactamases/genetics* ; Phylogeny ; Rural Population ; Carbapenems/pharmacology* ; Microbial Sensitivity Tests

Objective: To investigate the drug-resistant gene characteristics and core genome characteristics of carbapenem-resistant Enterobacter cloacae (CR-ECL) in rural residents of Weifang City, Shandong Province. Methods: Fecal samples were collected from rural community residents in Weifang City, Shandong Province in 2017. Drug-resistant strains were screened using a carbapenem-resistant enterobacter chromogenic medium. CR-ECL positive strains were acquired via Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry(MALDI-TOFMS) analysis. The antibiotic resistance phenotype of CR-ECL was determined using a microbroth dilution assay. Whole genome sequencing (WGS) and analysis were conducted, along with an examination of the immediate vicinity of the bla_NDM gene and phylogenetic analysis of the strains. Results: A total of 628 fecal samples were collected and tested, of which 6 were CR-ECL positive (detection rate 0.96%), all exhibiting multiple drug resistance (MDR) phenotypes. Six CR-ECL strains had four MLST genotypes (ST), all of which carried multiple drug resistance genes (bla_NDM-1, bla_NDM-5, etc.) and virulence genes (acrA, acrB, entB, fepC, etc.). There were mobile genetic elements ISAba125, TN3-IS3000, TN3 and IS5 in the genetic environment surrounding the bla_NDM gene. The phylogenetic tree showed that the multi-locus sequence typing of the core genome (cgMLST) was consistent with the single nucleotide polymorphism (SNPs) results. The cgMLST results showed that the allele differences between strains 2BC0101B and 2BC0251B, 2BG0561B and 2BI0221B were 2 and 1, respectively. The SNPs results showed that the above two pairs of bacteria also clustered together. It was found that the strains of chicken fecal samples in the National Center for Biotechnology Information (NCBI) database were located in the center of the evolutionary tree, and the local sequences could be traced back to American human sequences. Conclusion: Multidrug-resistant CR-ECL is detected in rural community residents in Weifang City, Shandong Province.
Humans ; Anti-Bacterial Agents/therapeutic use* ; Enterobacter cloacae/genetics* ; Multilocus Sequence Typing ; beta-Lactamases/genetics* ; Phylogeny ; Rural Population ; Carbapenems/pharmacology* ; Microbial Sensitivity Tests

Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; Enterobacter cloacae ; drug effects ; Isoelectric Point ; Microbial Sensitivity Tests ; Polymerase Chain Reaction ; beta-Lactamases ; genetics

The aminoglycoside 6'-N-acetyltransferases of type Ib (aac(6')-Ib) gene confers resistance to amikacin, tobramycin, kanamycin, and netilmicin but not gentamicin. However, some isolates harboring this gene show reduced susceptibility to amikacin. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommends a revision of the phenotypic description for isolates harboring the aac(6')-Ib gene. In this study, we determined the aminoglycoside susceptibility profiles of 58 AAC(6')-Ib-producing Enterobacter cloacae isolates. On the basis of the CLSI and EUCAST breakpoints, a large proportion (84.5% and 55.2%, respectively) of these 58 isolates were found to be susceptible to amikacin. However, among the isolates that were shown to be anikacin-susceptible according to the CLSI and EUCAST breakpoints, only 30.6% and 18.8% isolates, respectively, could be considered to have intermediate resistance on the basis of the EUCAST expert rules. Further studies should be conducted to determine the aminoglycoside susceptibility profiles of aac(6')-Ib-harboring isolates from various geographic regions and to monitor the therapeutic efficacy of amikacin in infections caused by these isolates.
Acetyltransferases/*genetics ; Amikacin/pharmacology ; Aminoglycosides/*pharmacology ; Anti-Bacterial Agents/*pharmacology ; Drug Resistance, Bacterial/genetics ; Enterobacter cloacae/*genetics/isolation & purification ; Enterobacteriaceae Infections/diagnosis/microbiology ; Humans ; Microbial Sensitivity Tests ; Polymerase Chain Reaction ; Sequence Analysis, DNA

OBJECTIVETo investigate the status of the drug resistance and the ampC gene expression of Enterobacter cloacae.

METHODSDisk diffusion tests were made for detecting the susceptibility of antimicrobial agents against Enterobacter cloacae. AmpC gene was amplified by polymerase chain reaction (PCR) and verified by DNA sequencing. AmpC gene expression was analyzed according to antimicrobial agent sensitive phenotype.

RESULTSThe sensitivity rates of 144 strains to imipenam, cefepime and cefoperazone/sulbactam were 98.61%, 65.97% and 63.89%, respectively. The sensitivity rates of 144 strains to other antimicrobial agents were lower. Among the 144 strains 120 were found to be positive by PCR for ampC. The PCR product showed high homology to the GenBank ampC sequence. Stably derepressed strains, hyperinducible strains and unexpressing or lower level expressing strains accounted for 30.0% (36/120), 37.5% (45/120), and 32.5% (39/120), respectively. Fifty-six out of 120 strains (46.67%) also produced extended spectrum beta-lactamases (ESBLs). The hyperinducible strains were highly sensitive to all the antimicrobial agents except amoxicillin/clavulanic acid and cefuroxime, while the stably derepressed strains were only sensitive to imipenam and cefepime. However, sensitivity to cefepime decreased if the strains also produced ESBLs.

CONCLUSIONSThe drug resistant status of Enterobacter cloacae is severe. Clearing out the expressive status of ampC gene will be helpful in selection of antimicrobial agents in the treatment of clinical infection.

Cefoperazone ; pharmacology ; Drug Resistance, Bacterial ; Enterobacter cloacae ; drug effects ; enzymology ; genetics ; Gene Expression ; Genes, Bacterial ; genetics ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Polymerase Chain Reaction ; Sulbactam ; pharmacology ; beta-Lactamases ; analysis

OBJECTIVETo explore the distribution of qnr gene and broad spectrum p-lactamase (ESBLs) gene in gram-negative bacteria which were isolated from our hospital patients.

METHODSqnr gene in nonrepetitive 129 isolates of Escherichia coli, 10 isolates of Enterobacter cloacac and 29 isolates of K. pneunoniae were detected by polymerase chain reaction (PCR). For qnr gene positive strains, int I, SHV-1, TEM-1, CTX-M, OXA-I , OXA-II , OXA-III, DHA and EBC genes were examined. Plasmid conjugatable test was applied to examine whether qnr gene was located in conjugate plasmid and ERIC-PCR was carried out for DNA homologous analysis. ESBLs detection (according to phenotypic confirmatory test based on National Committee for Clinical Laboratory Standards criteria) and susceptibility test to 16 antibiotics were also performed.

RESULTSqnr gene was found in 6 clinical isolates including 5 strain of E. coli and one strain of E. cloacac, but qnr gene was undetectable in K. pneunoniae isolates. The 6 clinical isolates were suspectible to imipenem but resistance to some other drugs while only 2 isolates of E. coli were susceptible to quinolone. Among the 6 qnr gene-positive strains, all of them belonged to I type integron-positive isolates, 4 isolates of them were TEM-1 producing strains,with only one isolate was OXA-III gene producing strain, and 2 isolates of them were EBC producing strains. Most of them were with 2 ESBLs gene if not more. qnr gene was on transferable plasmids which could be disseminated by clone.

CONCLUSIONIn Wuhan city, the prevalence of qnr was confirmed. qnr gene were found with some ESBLs gene in the same strains, and qnr gene in suspect strains. The transmission of qnr gene producing strains could be mediated by transferable plasmids or clone, forcing us to make intensive investigation and take effective control measures.

Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; DNA, Bacterial ; genetics ; Drug Resistance, Bacterial ; genetics ; Enterobacter cloacae ; drug effects ; genetics ; isolation & purification ; Escherichia coli ; drug effects ; genetics ; isolation & purification ; Escherichia coli Proteins ; genetics ; Genes, Bacterial ; Humans ; Imipenem ; pharmacology ; Klebsiella pneumoniae ; drug effects ; genetics ; isolation & purification ; Microbial Sensitivity Tests ; Plasmids ; genetics ; Quinolones ; pharmacology ; Sequence Analysis, DNA ; beta-Lactamases ; genetics