Drug resistance analysis of Enterobacter cloacae isolated from blood samples in Hebei, 2016-2021 / 中国热带医学

@# Objective　To investigate the drug resistance of Enterobacter cloacae isolated from blood samples in 75 member units of the Bacterial Drug Resistance Monitoring Network in Hebei, 2016- 2021, so as to provide a basis for rational drug use in clinic. Methods　WHONET 5.6 software was used to retrospectively analyze drug susceptibility of Enterobacter cloacae isolated from 32 secondary hospitals and 43 tertiary hospitals. SPSS19.0 software was used for statistical analysis. Results After removing the duplicate strains, 1 225 strains of E. cloacae were isolated from blood samples of 75 hospitals during 6 years, including 157 strains from secondary hospitals and 1 068 strains from tertiary hospitals. In this study, the resistance of Enterobacter cloacae to 16 kinds of antibiotics was analyzed. The drug resistance rates to cefuroxime (52.4%-67.8%), piperacillin (27.4%-31.2%), ceftazidime (27.8%-35.5%), ceftriaxone (29.5%-45.0%), aztreonam (22.2%-32.3%), cotrimoxazole (21.6%-28.7%) were higher; the resistance rates to amikacin and tobramycin were lower than 15.0%. The resistance rates to imipenem and meropenem were 3.6%-12.3% and 5.1%-11.4%, respectively. The resistance rate to ciprofloxacin in tertiary hospitals was 22.4%, and the resistance rate to cotrimoxazole was 23.9%. Except for these two antimicrobials, the resistance rates to other antimicrobial drugs in tertiary hospitals were higher than that in secondary hospitals. A total of 121 carbapenem-resistant Enterobacter cloacae strains were detected in the past 6 years, with an increasing detection rate (χ2trend=6.305, P=0.012). Conclusions　Enterobacter cloacae has great differences in antimicrobial resistance to different antibiotics, and is sensitive to carbapenems. The drug resistance in tertiary hospitals is generally higher than that in secondary hospitals. Drug resistance monitoring and drug resistance mechanism research should be strengthened to better guide clinical drug use and curb the rise of drug resistance.

Diagnosis and Treatment of Klebsiella Pneumoniae Combined with Enterobacter Cloacae in Lumbar Intervertebral Space Infection / 中山大学学报(医学科学版)

ObjectiveTo explore the clinical diagnosis and treatment of rare primary lumbar intervertebral space infection with Klebsiella pneumoniae and Enterobacter cloacae， and provide clinical experience for the diagnosis and treatment of this rare spinal infection. MethodsAn elderly male patient with low back pain and numbness in the left lower extremity for more than 7 months， which aggravated for more than 1 week， was diagnosed with lumbar disc herniation after laboratory and imaging examinations. After admission， the symptoms became acutely aggravated， and re-examination of lumbar enhanced MRI showed local enhancement at the posterior edge of the L3/4 intervertebral space. The VAS score was 9 points， and the lumbar JOA score was 6 points. A posterior lumbar interbody fusion of L3-L5 was performed， and L3/4 intervertebral disc specimens were collected during the operation for bacterial culture. ResultsBacterial culture results showed Klebsiella pneumoniae and Enterobacter cloacae infection. The patient was treated with sensitive antibiotics for 6 weeks after the operation， and the patient was cured during the follow-up of half a year after the operation. ConclusionFor middle-aged and elderly patients with clinical manifestations of acute severe low back pain or lower extremity pain， the possibility of spinal infection should be considered when routine laboratory and imaging examinations suggest lumbar degenerative diseases.

Genomic epidemiology analysis of Enterobacter hormaechei subsp. hoffmannii / 中华检验医学杂志

Objectives:To investigate the genetic characteristics of the blaNDM-1-carrying plasmid of the multidrug resistant Enterobacter hormaechei subsp. hoffmannii clinical isolate C37, and constructing a phylogenetic tree of the 66 publicly available genomes of the Enterobacter hormaechei subsp. hoffmannii to explore its global epidemic situation. Methods:Carbapenem-resistant Enterobacter cloacae complex (CRECC) strains isolated from the First Affiliated Hospital of Sun Yat-sen University from August 2014 to August 2021 were collected. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rDNA Sanger sequencing were used for species identification. Micro broth dilution method was used for antibacterial susceptibility test. The polymerase chain reaction (PCR) was used to detect the β-lactamase resistance gene and plasmid-mediated quinolone resistance (PMQR) gene carried by the C37 strain. The conjugation experiment was used to confirm the conjugative metastasis of the resistance genes in C37 strain. Whole genome of the C37 strain was sequenced. Core genome was extracted and the phylogenetic analysis of 66 publicly available Enterobacter hormaechei subsp. hoffmannii was performed. Results:Enterobacter hormaechei subsp. hoffmannii C37 strain is resistant to third-generation cephalosporins, carbapenems, aminoglycosides and quinolones, and carries blaACT-5, blaNDM-1, qnrA1, aac(6′)-Ib-cr, oqxAB, fosA, dfrA15 and other resistance genes, as well as IncX3, IncX4, IncFIB and IncFII plasmids. Multilocus sequence typing (MLST) analysis showed that C37 strain belongs to the ST78 type of Enterobacter cloacae complex (ECC). Conclusions:ST78 type Enterobacter hormaechei subsp. hoffmannii is closely related to the spread of carbapenem resistance genes. It is a potential high-risk clone to spread carbapenem resistance genes. The prevalence and trends of ST78 type Enterobacter hormaechei subsp. Hoffmannii should be monitored.

Abordaje interdisciplinario de endoftalmitis endógena neonatal. Reporte de caso / Interdisciplinary approach to endogenous neonatal endophthalmitis. Case report

La endoftalmitis endógena neonatal es una patología poco frecuente que puede causar daño ocular grave. Puede manifestarse en pacientes con comorbilidades, como nacimiento pretérmino, bajo peso al nacer, complicaciones posquirúrgicas perinatales o sepsis.El presente reporte de caso documenta a una paciente pretérmino que fue sometida a múltiples cirugías abdominales. Durante su internación, desarrolló sepsis, meningitis y endoftalmitis endógena neonatal. La frecuencia extremadamente baja de la endoftalmitis endógena a esta edad, la importancia de preservar la salud visual del paciente y el abordaje interdisciplinario son puntos importantes de aprendizaje en este caso.

Neonatal endogenous endophthalmitis is a rare condition that can cause serious eye injuries. It can manifest in patients with comorbidities, such as preterm birth, low birth weight, post-surgical perinatal complications, or sepsis.This case report documents a preterm patient who underwent multiple abdominal surgeries. During her hospitalization, she developed sepsis, meningitis and neonatal endogenous endophthalmitis. The extremely low frequency of endogenous endophthalmitis at this age, the importance of preserving the patient's visual health, and the interdisciplinary approach are important learning points in this case.

Molecular, biochemical, and phenotypic characterization of a newly isolated Enterobacter hormaechei subsp. xiangfangensis strain associated with diarrhea cases in Iraq

Aims@#The current study aimed to isolate and characterize bacterial strains associated diarrhea with the focus on Enterobacter species strains and test for susceptibility to antibiotics.@*Methodology and results@#A total of 400 stool samples from inpatients suffering from diarrhea in Al-Qasim Hospital at Al-Hilla City of Iraq were screened form January 2018 to January 2019. Phenotypic, molecular, and biochemical methods were used to identify the isolated bacteria. A new strain of Enterobacter hormaechei was obtained from two stool samples of inpatients suffering from diarrhea for more than two weeks. This strain is Gram negative, rod shaped, and facultative anaerobic. Multiple sequence alignment analysis and phylogenetic tree construction of the sequenced 16S rRNA gene of the isolated strain suggested that this strain can be identified as E. hormaechei subsp. xiangfangensis, named as E. hormaechei subsp. xiangfangensis strain AA1. This strain was resistant to augmentin, ampicillin, cephalothin, cefoxitin, ceftazidime, cefixime, ticracillin/clavulanic acid, cefotaxime, streptomycin, erythromycin, amikacin, ciprofloxacin, and chloramphenicol, while it was susceptible to meropenem along with imipenem. @*Conclusion, significance and impact of study@# In the present study, E. hormaechei subsp xiangfangensis was isolated for the first time in Iraq and was resistant to most of the tested antibiotics, making it an etiologic agent that is not easy to be treated.

Risk factors for healthcare-associated pneumonia caused by carbapenem-resistant Enterobacter cloacae in patients in intensive care unit / 中国感染控制杂志

Objective To explore risk factors for healthcare-associated pneumonia (HAP) caused by carbapenemresistant Enterobacter cloacae (CREC) in patients in intensive care unit (ICU).Methods From July 2013 to June 2017, 64 patients with CREC-HAP in ICU of a hospital were collected as case group, and 64 patients with carbapenem-sensitive Enterobacter cloacae HAP (CSEC-HAP) were as control group, risk factors for the occurrence of CREC-HAP were analyzed retrospectively by 1∶1 matched case-control study.Results Univariate analysis showed that APACHE II score≥20, long length of ICU stay, use of ventilator, long length of ventilator use, use of carbapenems, long duration of antimicrobial use, and at least 2 kinds of antimicrobial agents combined use were associated with the occurrence of CREC-HAP (all P＜0.05).Multivariate logistic regression analysis showed that APACHE II score≥20, use of ventilator, long length of ventilator use, use of carbapenems, and long duration of antimicrobial use were independent risk factors for occurrence of CREC-HAP (all P＜0.05).Conclusion Risk factors for occurrence of CREC-HAP in ICU patients include the use of carbapenems, long length of ventilator use, long duration of antimicrobial use, and APACHE II score≥20.Effective preventive and control measures can be formulated and taken in view of the above risk factors.

Matricaria Recutita Extract (Chamomile) to reduce Candida Albicans and Entrobacter Cloacae biofilms: in vitro study / Extrato de Matricaria recutita (camomila) para redução do biofilme de Candida albicans e Entrobacter cloacae: estudo in vitro

ABSTRACT Objective: This research study aimed at evaluating the inhibitory activity of Matricaria recutira (chamomile) hydroalcoholic extract on Candida albicans and Enterobacter cloacae biofilms. Methods: C. albicans and E. cloacae biofilms with thirty-hour formation were submitted, for five minutes, to 100, 200 and 300 mg / mL of M. recutita hydroalcoholic extract, chlorhexidine digluconate 0.12% (Periogard® - inhibition control) or sterile distilled water (growth control). Subsequently, they were washed and divided into two groups to determine the microbial viability: G/UFC - counting of colony forming units (cfu) in agar and G/DNA - quantification of viable DNA with violet crystal dye by spectrophotometry. Results: M. recutita extract at 300 mg/mL reduced significantly (p <0.01) the E. cloacae cfu/mL number in biofilm with results similar to chlorhexidine 0.12%, while extracts at 100 and 200 mg/mL did not have the same effectiveness. The amount of E. cloacae viable DNA was reduced (p <0.05) in all the M. recutita extract concentrations and chlorhexidine. There was no significant difference (p = 0.565) in the cfu/mL number or in the amount of viable DNA (p = 0.8094) in C. albicans biofilm when compared to untreated biofilm (control) or, even, between the extracts when compared to each other or to chlorhexidine 0.12%. Conclusion: 300 mg/mL M. recutita extract reduced significantly the E. cloacae biofilm but not the C. albicans, both with a similar result to chlorhexidine 0.12% (Periogar®).

RESUMO Objetivo: Avaliar a atividade inibitória do extrato hidroalcoólico de Matricaria recutira (camomila) sobre biofilme de Candida albicans e Enterobacter cloacae. Métodos: Biofilmes de C. albicans e E. cloacae com trinta horas de formação foram submetidos por cinco minutos a 100, 200 e 300 mg/mL de extrato hidroalcoólico de M. recutita, digluconato de clorexidina 0,12% (Periogard® - controle de inibição) ou água destilada esterilizada (controle do crescimento). Depois foram lavados e divididos em dois grupos para determinação da viabilidade microbiana: G1 - contagem de unidades formadoras de colônia (ufc) em ágar e G2 - quantificação de DNA viável com corante cristal violeta por espectrofotometria. Resultados: O extrato de M. recutita a 300 mg/mL reduziu significativamente (p < 0,01) o número de ufc/mL de E. cloacae em biofilme com resultados semelhantes a clorexidina 0,12%, enquanto os extratos a 100 e 200 mg/mL não tiveram a mesma efetividade. Já a quantidade de DNA viável de E. cloacae foi reduzida (p < 0,05) em todas as concentrações do extrato de M. recutita testadas e clorexidina. Não houve diferença significativa (p=0,565) no número de ufc/mL ou na quantidade de DNA viável (p=0,8094) no biofilme de C. albicans quando comparado ao biofilme sem tratamento (controle) ou mesmo entre as concentrações do extrato quando comparados entre si ou com a clorexidina 0,12%. Conclusão: O extrato de M. recutita 300 mg/mL reduziu significativamente o biofilme de E. cloacae mas não de C. albicans, ambos com resultado semelhante à clorexidina 0,12% (Periogar®).

Biological and Genetic Characteristics of Clinically Isolated Enterobacter cloacae with Multidrug Resistance

BACKGROUND: From January 2014 to December 2015, 69 clones of Enterobacter cloacae showing multidrug resistance to six classes of antimicrobial agents were collected from two medical centers in Korea. METHODS: Minimum inhibitory concentrations were determined using the E-test method, and 17 genes were detected using polymerase chain reaction (PCR). The epidemiological relatedness of the strains was identified using repetitive element sequence-based PCR and multilocus sequence typing. RESULTS: The 69 E. cloacae clones produced extended spectrum β lactamase (ESBL) and AmpC and showed multidrug resistance to cefotaxime, ceftazidime, and aztreonam. We identified the following sequence types: ST56 of type VI for ESBL SHV (N=12, 17.4%); ST53, ST114, ST113, and ST550 of types I, IV, VI, and VII, respectively, for CTX-M (N=11, 15.9%); and ST668 of type III for the carbapenemase NDM gene (N=1, 1.5%). The AmpC DHA gene (N=2, 2.89%) was confirmed as ST134, although its type was not identified, whereas EBC (MIR/ACT; N=18, 26.1%) was identified as ST53, ST24, ST41, ST114, ST442, ST446, ST484, and ST550 of types V, I, III, IV, VII, and VI, respectively. The formed subclasses were bla CTX-M-3 and bla CTX-M-22 by CTX-M-1, bla CTX-M-9 and bla CTX-M-125 by CTX-M-9, bla DHA-1 by DHA, and bla MIR-7 and bla ACT-15,17,18,25,27,28 by EBC (MIR/ACT). CONCLUSIONS: There were no epidemiological relationships between the gene products and the occurrence of resistance among the strains.

Detection of virulence and ß-lactamase encoding genes in Enterobacter aerogenes and Enterobacter cloacae clinical isolates from Brazil

ABSTRACT Enterobacter cloacae and E. aerogenes have been increasingly reported as important opportunistic pathogens. In this study, a high prevalence of multi-drug resistant isolates from Brazil, harboring several β-lactamase encoding genes was found. Several virulence genes were observed in E. aerogenes, contrasting with the E. cloacae isolates which presented none.

Detection of virulence and -lactamase encoding genes in Enterobacter aerogenes and Enterobacter cloacae clinical isolates from Brazil

ABSTRACT Enterobacter cloacae and E. aerogenes have been increasingly reported as important opportunistic pathogens. In this study, a high prevalence of multi-drug resistant isolates from Brazil, harboring several -lactamase encoding genes was found. Several virulence genes were observed in E. aerogenes, contrasting with the E. cloacae isolates which presented none.

Analysis of Clinical Distribution and Drug Resistance of Non-sputum Specimen AmpC Enzyme-producing Enterobacter cloacae in a Hospital during 2011-2017 / 中国药房

OBJECTIVE:To provide reference for rational drug use and hospital infection control. METHODS:AmpC enzyme-producing Enterobacter cloacae were isolated from non-sputum specimen of a hospital during Jan. 2011-Oct. 2017. Drug sensitivity test was conducted by using MIC. The situation of AmpC enzyme production was confirmed by three dimensional test, and that of ESBLs-producing stain was detected with double-disk synergy test. RESULTS:There were 546 strains of AmpC enzyme-producing E. cloacae isolated from non-sputum specimen of the hospital,accounting for 4.80% of non-sputum specimen (546/11 375)and 38.97% of E. cloacae(546/1 401). Top 3 non-sputum samples in the list of detection rate were wound secretion (27.29%),midstream urine(25.82%)and blood(21.79%),and the departments with high detection rate were ICU(22.89%), neurosurgery department(18.68%)and general surgery department(16.67%). Resistance rate of AmpC enzyme-producing E. cloacae to most commonly used antibiotics was higher than 40%. There was statistical significance in resistant rate of the bacteria to ceftriaxone, cefotaxime, gentamicin, nitrofurantoin, levofloxacin, piperacillin/tazobactam, cefoperazone, ceftazidime,cefepime,tobramycin and minocycline among different years (P<0.05). The resistant rate to imipenem and meropenem was lower than 2%. Among 546 strains of AmpC enzyme-producing E. cloacae,68 strains of ESBLs were detected,and detection rates were 5.77%,6.06%,8.70%,10.26%,13.79%,17.35%,18.75% during 2011-2017. CONCLUSIONS:AmpC enzyme-producing E. cloacae are mainly isolated from samples as wound secretion and midstream urine,and mainly come from ICU and neurosurgery department. The drug resistance of the bacteria is severe,and drug resistance of the bacteria to antibiotics as β-lactams and quinolones is increased significantly. The detection rate of ESBLs-producing strain increases year by year. The bacteria are sensitive to carbapenems antibiotics,which can be regarded as first choice. It is necessary to strengthen drug resistance and enzyme production monitoring of AmpC enzyme-producing E. cloacae,select antibiotics combined with results of drug sensitivity test so as to prevent or delay the rapid increase of its resistance rate.

Research progress of infection and drug-resistances mechanism of Enterobacter cloacae / 中国人兽共患病学报

Enterobacter cloacae is a facultative anaerobic Gram-negative bacteria,and it mainly causes pulmonary infection.It was one of the most common conditioned pathogens in recent years,and its treatment and drug resistances have attracted more and more attention.Meanwhile,there were many further studies about antimicrobial susceptibility and drug-resistance mechanisms of E.cloacae.E.cloacae shows multi-drug resistance to antibiotics through complex resistant mechanisms.The study gives a brief review on the infection treatments and drug-resistance mechanisms of Enterobacter cloacae.

Detection of a strain of Enterobacter cloacae co-carrying NDM-1 and KPC-2 genes and its drug resistance / 中华临床感染病杂志

Objective To identify the drug resistance-related genes in a clinically isolated strain of Enterobacter cloacae.Methods A strain of Enterobacter cloacae was isolated from sputum of a patient with chronic obstructive pulmonary disease from the Affiliated Hospital of Xuzhou Medical University in March 2013.Modified Hodge test and metal enzyme inhibition test were performed for drug-resistant phenotype screening.Carbapenemase genes blaMUS-1, blaVIM-1, blaVIM-2, blaIMP, blaKPC-2, blaNDM-1, blaOXA-48 and blaGESwere amplified by polymerase chain reaction (PCR), and the positive products were sequenced and analyzed.Plasmid conjugation and transformation experiments were used to confirm that the resistance gene mediated by plasmids.Agar dilution method was used for antibiotic susceptibility test.Results Both modified Hodge test and metal enzyme inhibition test were positive in this strain of Enterobacter cloacae.blaNDM-1 gene and blaKPC-2 gene were detected by PCR, and further confirmed by sequencing.blaNDM-1 gene was carried by IncX plasmid with 54×103 bp, KPC-2 gene was carried by untyping plasmid with 42×103 bp.The strain was only sensitive to tetracycline (MIC=2 μg/mL) and tigecycline (MIC=1 μg/mL).The symptoms were improved after the patient was treated by tigecycline combined with Piperacillin/Tazobactam.Conclusion blaNDM-1 and blaKPC-2 genes in Enterobacter cloacae can be mediated by plasmids, and appropriate therapy for its infection should be based on the result of antibiotic susceptibility test.

Molecular epidemiological survey on an infection outbreak due to contamination of fiberbronchoscope / 中国感染控制杂志

Objective To investigate the causes of a healthcare-associated lower respiratory tract infection(HA-LRTI) outbreak due to Enterobacter cloacae(E.cloacae), and provide basis for clinical prevention and control of HAI.Methods Epidemiological data of patients with E.cloacae HA-LRTI following bronchoalveolar lavage(BAL) in the departments of respiratory disease and thoracic surgery of a hospital were collected, antimicrobial resistance analysis on isolated pathogens from patients and environment was performed, pulsed-field gel electrophoresis (PFGE) was used for genotyping.Results On March 8-16, 2013, a total of 15 patients underwent BAL in the fiberobronchoscopy room in the departments of respiratory disease and thoracic surgery of a hospital, 13 of whom developed E.cloacae LRTI, 4 cases were community-associated infection (the initial case was included), the other 9 cases were HAI;8 environmental specimens were detected 2 strains of E.cloacae, the strains were from vacuum suction joint of fiberbronchoscope and scissors used for trimming disposable controllable sputum suction pipeline.15 strains of E.cloacae from environment and patients were screened by antimicrobial susceptibility testing, 11 strains were with similar antimicrobial susceptibility testing result, 2 of which were environmental strains, 6 were from inpatients, and 3 were from patients in community.PFGE typing of 11 strains revealed that there were 8 strains with the same genotype, 6 of which were from patients in department of thoracic surgery, 2 were from vacuum suction joint of fiberbronchoscope and scissors used for disposable controllable sputum suction pipeline;the other 3 strains were of the same genotype, and from departments of respiratory disease and thoracic surgery.Conclusion This outbreak is due to contamination of bronchofibroscope by the same E.cloacae strain, the strain is susceptible to the clinic commonly used antimicrobial agents, such events should be paid attention in clinic, the key to control infection is to take necessary measures for cutting off the spread of the epidemic.

Construction of blaNDM-1gene deletion mutant of Enterobacter cloacae and analysis of its biological characteristics / 中华微生物学和免疫学杂志

Objective To construct a blaNDM-1gene deletion mutant of Enterobacter cloacae and to analyze its biological characteristics. Methods The blaNDM-1gene deletion mutant was constructed by using Red homologous recombination technology and verified by PCR and RT-qPCR. Antimicrobial susceptibility profiles,growth curves and in vitro competition abilities of the original strain and the blaNDM-1gene deletion mutant were analyzed. Results PCR,DNA sequencing and RT-qPCR showed that the blaNDM-1gene dele-tion mutant was successfully constructed. Antimicrobial susceptibility test showed that the original strain was resistant to imipenem,meropenem and ertapenem, while the blaNDM-1gene deletion mutant was sensitive to all. The original strain and the blaNDM-1gene deletion mutant had similar growth curves in Luria-Bertani liq-uid medium. In vitro competition experiment revealed that the competitive index of them was 0.69. Conclu-sion Red homologous recombination technology can be used to knockout the blaNDM-1gene of Enterobacter cloacae,which is associated with antimicrobial resistance and competitiveness.

Antibiotic-resistant mechanisms of plasmid pA1137 carrying aminoglycoside resistance gene aacC2 / 军事医学

Objective To achieve detailed genomic characterization and investigate the antibiotic-resistant mechanisms of plasmid pA1137 carrying the aminoglycoside resistance gene aacC2.Methods Antibiotic-resistant genes were deter-mined by PCR.Conjugation experiments were performed to verify the transferability of plasmid pA 1137.The minimum in-hibitory concentration(MIC)values of bacterial strains were tested with microdilution method.The genetic background, mobile elements and antibiotic resistance mechanisms of pA 1137 were determined using a whole genome sequencing meth-od.Results Both carbapenem-resistant gene blaIMP-8and aminoglycoside-resistant genes aacC2 and aacA4 were carried by A1137 isolated from Enterobacter cloacae(ECL).aacC2 was located in plasmid pA1137 while the other two resistant genes were observed in chromosomes.Plasmid pA1137 was an IncFⅡplasmid,whose total length was 68.97 kb,and GenBank accession number was MF190369.Plasmid pA1137 contained multiple replicons and intact conjugative transfer regions,so it could be transferred into ECL through conjugation experiments and confer corresponding antibiotic resistance to the transconjugant A1137-EC600.Conclusion IncFⅡ plasmid pA1137 has a single accessory region, the first reported Tn5403-based aacC2-tmrB-related region,which can cause stable inheritance and mediate the resistance to aminoglycoside antibiotics in ECL A1137.

High prevalence of plasmid-mediated quinolone resistance determinants in Enterobacter cloacae isolated from hospitals of the Qazvin, Alborz, and Tehran provinces, Iran

Abstract: INTRODUCTION: Plasmid-mediated quinolone resistance (PMQR) is a growing clinical concern worldwide. The main aims of this study were to detect qnr-encoding genes and to evaluate the clonal relatedness of qnr-positive Enterobacter cloacae isolates. METHODS: A total of 116 E. cloacae isolates that were not susceptible to quinolone were obtained from seven hospitals in Tehran, five hospitals in Qazvin, and two hospitals in Karaj (Iran). Bacterial identification was performed using standard laboratory methods and API 20E strips. Quinolone resistance was determined using the Kirby-Bauer disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guidelines. PCR and sequencing were employed to detect qnrA, qnrB, and qnrS genes, and clonal relatedness was assessed using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method. RESULTS: In total, 45 (38.8%) and 71 (61.2%) of isolates showed high- and low-level quinolone resistance, respectively, and qnr-encoding genes were detected in 70 (60.3%) of them. qnrB1 [45 (38.8%) isolates] was the most commonly detected gene, followed by qnrS1 [28 (24.1%) isolates] and qnrB4 [18 (15.5%) isolates] either alone or in combination with other genes. The results of the ERIC-PCR revealed that 53 (75.7%) qnr-positive isolates were genetically unrelated. CONCLUSIONS: This study describes, for the first time, the high prevalence of the qnrB1, qnrS1, and qnrB4 genes among E. cloacae isolates in Iran. The detection of qnr genes emphasizes the need for establishing tactful policies associated with infection control measures in hospital settings in Iran.

The dissemination mode of drug-resistant genes in Enterobacter cloacae.

Background: Enterobacter cloacae (E. cloacae) infection has the highest mortality rate among Enterobacter infections. This study aimed to determine the prevalence and the transmission route of the class I integron, qnr genes, and CTX-M ESBLs genes in clinical isolates and to analyse the association between the prevalence of MDR genes and the antibiotic resistance of E. cloacae. Materials and Methods: The antibiotic susceptibility was tested the agar dilution method. The class I integron, qnr genes, and CTX-M ESBLs genes were detected by polymerase chain reaction (PCR). The prevalence data were analysed with the Chi-square test. Results: In the 100 clinical isolates, the class I integron-positive rate was 65%, with 12% on chromosome, 15% on plasmids and 38% on both. The positive rate of qnr genes was 37% with plasmid location. The positive rates for qnrA, qnrB and qnrS were 6%, 23% and 8%, respectively. The CTX-M ESBLs-positive rate was 34%. For CTX-M-1 ESBLs, 15% were on chromosome, 6% on plasmids and 4% on both; for CTX-M-9 ESBLs, 1% was on chromosome and 7% on plasmid; for CTX-M-25 ESBLs, 3% were on chromosome and 1% on plasmid. Conclusion: Antibiotic resistance genes may be horizontally and vertically disseminated among E. cloacae, which helps multidrug-resistant (MDR) strains of E. cloacae to be successful nosocomial agents.

Detection of Enterobacter cloacae produced AmpC enzymes and ESBLs and study of its multi-drug resistance mechanism / 国际检验医学杂志

Objective To explore the prevalence and antimicrobial resistance mechanism of multiple drug resistance Enterobacter cloacae in ShenZhen region .Methods We screened 72 strains of multi resistant strains from 82 strains of Enterobacter cloacae iso‐lated from on clinical .And detected extended spectrum beta lactamases (ESBLs) and sustained high AmpC enzyme with ESBLs phenotypic confirmatory test and flucloxacillin (FCC ) double inhibitor diffusion synergy test method (DIDST ) .Results In 82 strains of Enterobacter cloacae isolated on clinical ,33 strains (40 .2% ) derepressed Hyperproducing AmpC enzymes ,25 strains (30 .5% ) produced ESBLs ,14 strains (17 .1% ) produced AmpC enzyme and ESBLs parallelly ,10 strains (12 .2% ) didn′t express the two enzymes .Conclusion High expression of AmpC enzyme and ESBLs is the main mechanism of cephalosporin resistant En‐terobacter cloacae .High AmpC enzyme and ESBLs production and widely used of beta amide antibacterial drug have a direct rela‐tionship .The first choice of treatment of multi drug resistant Enterobacter cloacae should be carbapenem .

Clinical distribution and changing resistant pattern of Enterobacter cloacae / 中国感染与化疗杂志

Objective To investigate the distribution and resistant pattern of Enterobacter cloacae to antimicrobial agents for reasonable use of antibiotics .Methods E .cloacae strains were isolated from patients from January 2009 to December 2013 .The strains were identified by VITEK‐2 Compact System of BioMerieux and tested for antimicrobial susceptibility by Kirby‐Bauer disk diffusion method .The results were analyzed .Results A total of 397 nonduplicate E .cloacae strains were isolated during 5 years ,accounting for 5 % of the total gram‐negative isolates . The strains were mainly isolated from sputum (48 .9% ) , followed by secretions (30 .5% )and urine (7 .3% ) .The percentage of E .cloacae strains resistant to all the antibiotics tested was on decline except carbapenems ,cefoxitin and amoxicillin‐clavulanic acid .Carbapenems were relatively more active against E .cloacae strains .The E .cloacae strains showed higher resistance rate toβ‐lactams .Conclusions It is necessary to strengthen the monitoring of clinical isolates to guide rational use of antimicrobial agents .