Acinetobacter baumannii ; classification ; genetics ; isolation & purification ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Phylogeny

OBJECTIVETo study the mode of transmission and molecular characteristics on carbapenem-resistant Acinetobacter baumannii strain. Strains were isolated from different parts of samples in various patients.

METHODSClinical information of carbapenem-resistant Acinetobacter baumannii isolates were stored and analyzed by WHONET 5.4 software. The transmission and pathopoiesis of the strains were learned through case file review. Genotypes of isolates were identified by pulse-field gel electrophoresis (PFGE) and genes of carbapenemase were detected by multiple PCR, in order to find molecular characteristics and relatedness between strains.

RESULTS29 stains of Acinetobacter baumannii resistant to carbapenem were isolated from 2 or more kinds of samples among 13 patients'. Two genotypes were identified by PFGE: genotype A was obtained from 22 isolates in 11 patients and genotype B was obtained from 7 isolates in 4 patients. PCR amplification showed that all strains possessed OXA-23 gene except 1, and all strains possessed Integrase gene I except 3.

CONCLUSIONThere were 2 different genotypes from 29 strains of carbapenem-resistant Acinetobacter baumannii with Genotype A as the main type. OXA-23 carbapenemase gene and integrase gene I were detected from most of the isolates. All the strains could be easily transmitted in the body of the patients and among patients, hence becoming the epidemic pathogen of iatrogenic infection.

Acinetobacter Infections ; microbiology ; transmission ; Acinetobacter baumannii ; classification ; drug effects ; genetics ; Carbapenems ; pharmacology ; Cross Infection ; microbiology ; transmission ; Drug Resistance, Bacterial ; genetics ; Genotype ; Humans

OBJECTIVETo study the risk factors of Acinetobacter baummanii in nosocomial infections, and to verify the nature of Acinetobacter baumannii strains isolated from intensive care unit (ICU).

METHODSA hundred and fourty patients associated with nosocomial infection of Acinetobacter baummanii from four teaching hospitals were selected and compared with controls through a case control study to identify risk factors. The strains isolated from the ICU were typed by polymerase chain reaction (PCR) with the primer M(13) following electrophoresis in agarose gel.

RESULTSThe odds ratios (ORs) were: state of the illness (OR = 8.69), using immunosuppressant (OR = 4.85), mechanical ventilation (OR = 3.68) and treatment with 3 kinds of antibiotics (OR = 3.014). Data from PCR studies indicated that these strains were sharing identical band pattern from the five strains.

CONCLUSIONRisk factors for nosocomial infection with Acinetobacter baummanii included state of an illness, immunosuppressant, mechanical ventilation, and treatment with antibiotics. A multidrug-resistant strains of Acinetobacter baumannii was identified in ICU.

Acinetobacter baumannii ; classification ; genetics ; Cross Infection ; etiology ; microbiology ; Genotype ; Humans ; Logistic Models ; Polymerase Chain Reaction ; Risk Factors

OBJECTIVETo analyse the plasmid-mediated SHV type beta-lactamases-encoding genes sequence and to identify its subtype of multiple-drug-resistant acinetobacter baumannii isolated from Huzhou district, Zhejiang province, China.

METHODSSixty strains of acinetobacter baumannii were isolated from hospitalized patients between Jul, 2000 and Dec, 2002. Susceptibility of antimicrobial agents and confirmatory tests for Extended-spectrum beta-lactamases (ESBLs) were tested by microdilute method. SHV type beta-lactamases-encoding genes were tested by polymerase chain reaction (PCR). SHV sequences of acinetobacter baumannii HZ02 and HZ10 strains were detected by ABI automated sequencer and were analysed to compare with SHV genes that had been published in GenBank.

RESULTSEighteen (30.0%) strains of acinetobacter baumannii isolated between Jun, 2001 and Jan, 2002 were carrying SHV beta-lactamases resistant gene of plasmids. Detected SHV sequences of acinetobacter baumannii HZ02 strain and HZ10 strain had 825 and 833 nucleotides respectively and had the same gene sequence as the gene encoding SHV-12 subtype of ESBLs discovered in Switzerland.

CONCLUSIONSThirty percentage of the clinically isolated acinetobacter baumannii were carrying SHV type (extended-spectrum) beta-lactamases resistant gene of plasmids and causing an outbreak in hospital and was discovered to have carried the strains of SHV-12 subtype producing ESBLs gene in acinetobacter baumannii which was the first reported case in the world.

Acinetobacter Infections ; epidemiology ; microbiology ; Acinetobacter baumannii ; enzymology ; genetics ; isolation & purification ; Amino Acid Sequence ; Base Sequence ; China ; epidemiology ; DNA, Bacterial ; genetics ; isolation & purification ; Drug Resistance, Multiple ; Humans ; Molecular Epidemiology ; Molecular Sequence Data ; Sequence Analysis, DNA ; beta-Lactamases ; classification ; genetics

BACKGROUND: Acinetobacter baumannii has a greater clinical impact and exhibits higher antimicrobial resistance rates than the non-baumannii Acinetobacter species. Therefore, the correct identification of Acinetobacter species is clinically important. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has recently become the method of choice for identifying bacterial species. The purpose of this study was to evaluate the ability of MALDI-TOF MS (Bruker Daltonics GmbH, Germany) in combination with an improved database to identify various Acinetobacter species. METHODS: A total of 729 Acinetobacter clinical isolates were investigated, including 447 A. baumannii, 146 A. nosocomialis, 78 A. pittii, 18 A. ursingii, 9 A. bereziniae, 9 A. soli, 4 A. johnsonii, 4 A. radioresistens, 3 A. gyllenbergii, 3 A. haemolyticus, 2 A. lwoffii, 2 A. junii, 2 A. venetianus, and 2 A. genomospecies 14TU. After 212 isolates were tested with the default Bruker database, the profiles of 63 additional Acinetobacter strains were added to the default database, and 517 isolates from 32 hospitals were assayed for validation. All strains in this study were confirmed by rpoB sequencing. RESULTS: The addition of the 63 Acinetobacter strains' profiles to the default Bruker database increased the overall concordance rate between MALDI-TOF MS and rpoB sequencing from 69.8% (148/212) to 100.0% (517/517). Moreover, after library modification, all previously mismatched 64 Acinetobacter strains were correctly identified. CONCLUSIONS: MALDI-TOF MS enables the prompt and accurate identification of clinically significant Acinetobacter species when used with the improved database.
Acinetobacter Infections/*microbiology/pathology ; Acinetobacter baumannii/*chemistry/classification/isolation & purification ; Bacterial Proteins/chemistry/genetics/metabolism ; Databases, Factual ; Humans ; Phylogeny ; RNA, Ribosomal, 16S/chemistry/genetics/metabolism ; *Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

BACKGROUNDAcinetobacter baumannii has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. However, of the frequently used methods, pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) in Acinetobacter baumannii genotyping lack the direct molecular proof of drug resistance. This study was conducted to establish a typing method based on drug resistant gene identification in contrast to traditional PFGE and AFLP in the period of nosocomial epidemic or outbreak.

METHODSFrom January 2005 to October 2005, twenty-seven strains of Acinetobacter species from Intensive Care Units, the Second Affiliated Hospital in Ningbo were isolated, including both epidemic and sporadic events. Susceptibility test, PFGE, AFLP and drug resistance gene typing (DRGT) were carried out to confirm the drug resistance and analyze the genotyping, respectively. PFGE was used as a reference to evaluate the typeability of DRGT and AFLP.

RESULTSTwenty-seven strains of Acinetobacter displayed multiple antibiotic resistance and drug resistant genes, and beta-lactamase genes were detected in 85.2% strains. The result of DRGT was comparable to PFGE in Acinetobacter strains with different drug resistance though a little difference existed, and even suggested a molecular evolution course of different drug-resistant strains. AFLP showed great polymorphism between strains and had weak ability in distinguishing the drug resistance.

CONCLUSIONCompared to AFLP and PFGE, DRGT is useful to analyze localized molecular epidemiology of nosocomial infections and outbreaks, which would benefit clinical diagnosis and therapy.

Acinetobacter Infections ; microbiology ; Acinetobacter baumannii ; classification ; drug effects ; genetics ; Amplified Fragment Length Polymorphism Analysis ; Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; physiology ; Electrophoresis, Gel, Pulsed-Field ; Genotype ; Microbial Sensitivity Tests ; Polymerase Chain Reaction

OBJECTIVETo characterize the genetic background of multidrug-resistant Acinetobacter baumannii (A. baumannii) from China, and the population structure of this pathogen.

METHODSA previously reported MLST scheme was applied to a collection of 33 multidrug-resistant strains of A. baumannii from China, and the data of all the strains in the A. baumannii MLST database were downloaded for the population structure analysis. The sequence types and clonal complexes were identified, the presence or absence of recombination was analyzed for each MLST locus, and the values of I(A)(S), and recombination/mutation ratio were calculated for the whole strain collection. A phylogenetic tree was constructed using all the allelic profiles in the database.

RESULTSA total of six sequence types were identified from the 33 Chinese strains tested, and 29 of these strains belonged to the CC92 clonal complex. Three (gdhB, gpi, and rpoD) of the seven MLST loci (gltA, gyrB, recA, cpn60, gdhB, gpi, rpoD) had undergone recombination with statistical evidence. For all allele profiles in the MLST database, the I(A)(S) value was 0.155 and the recombination/mutation ratio was 6.083. Sequence types from each clonal complex were grouped closely in the phylogenetic tree, which gave an overview of the microevolution of this pathogen.

CONCLUSIONThe spread of multidrug-resistant A. baumannii in China was closely related to the CC92 clonal complex. A. baumannii had an 'epidemic' population structure, i.e., a superficially clonal structure with high levels of recombination, in which successful epidemic clones arise especially including worldwide dissemination of the CC92 clonal complex to cause a widespread occurrence of multidrug-resistant infections.

Acinetobacter baumannii ; classification ; genetics ; isolation & purification ; Bacterial Typing Techniques ; China ; Cluster Analysis ; DNA, Bacterial ; genetics ; Drug Resistance, Multiple, Bacterial ; Genetic Variation ; Genetics, Population ; Molecular Epidemiology ; Molecular Sequence Data ; Multilocus Sequence Typing ; Phylogeny

OBJECTIVETo investigate the genotype of blaADC which was a kind of AmpC produced by Acinetobacter baumannii (AB), isolated through the detection of 28 similar strains among children.

METHODS28 strains of AB were collected and isolated from the Pediatrics clinic during 2006, and were identified through bacteria and susceptibility test using Vitex-32 automicroscan GNI and GNS cards. The genotype of blaADC was confirmed by polymerase chain reaction (PCR) and them sequenced.

RESULTS3 of the 28 strains of AB showed multi-drugs resistance, with a positive rate of 10.71%. blaADC was discovered in 17 of the 28 strains and the positive rate was 60.71%. All the 28 strains of AB were resistant to Cefoxitin. blaADC positive strains were all sensitive to Ampicil/Sulbactam, and only one of them was resistant to Piperacillin/Tazobactan. There were no blaADC genes discovered in the strains that were resistant to Ampicil/Sulbactam or Piperacillin/Tazobactan. There were changes of amino acids on the site 4, 242, 342 and 376 in the sequence of blaADC of No.2 strain, comparing to gi /7258342/ emb /CAB77444. 1/ in GenBank.

CONCLUSIONAbove 60% of the AB isolated in children were carrying blaADC while a strain was collected from them at random. When they were undertaken nucleotide sequence analysis, significant difference was found from the others that landed in GenBank, which identified itself as new subtype.

Acinetobacter Infections ; microbiology ; Acinetobacter baumannii ; classification ; drug effects ; genetics ; isolation & purification ; Amino Acid Sequence ; Anti-Bacterial Agents ; pharmacology ; Bacterial Typing Techniques ; Child ; DNA, Bacterial ; genetics ; Drug Resistance, Multiple, Bacterial ; genetics ; Genotype ; Humans ; Microbial Sensitivity Tests ; Molecular Sequence Data ; Sequence Alignment ; Sequence Analysis, DNA ; beta-Lactamases ; genetics

PURPOSE: The increasing prevalence and global spread of carbapenem-resistant Acinetobacter baumannii (A. baumannii) has become a serious problem. The aim of this study was to investigate molecular and epidemiological characteristics of carbapenem-resistant A. baumannii isolates collected from Korean non-tertiary hospitals. MATERIALS AND METHODS: Thirty six non-duplicated carbapenem-resistant A. baumannii isolates were collected from 17 non-tertiary hospitals in Korea between 2004 and 2006. Isolates were typed by multilocus sequence typing and repetitive-sequence-based PCR (rep-PCR). Detection of genes encoding OXA carbapenemase and their relationship with ISAba1 was performed by PCR. RESULTS: Two clones were prevalent among 36 isolates: ST69 (17 isolates, 47.2%) and ST92 (19 isolates, 52.8%). Rep-PCR patterns were diverse and revealed that all isolates were clustered into eight band patterns. The ISAba1-activated blaOXA-23-like and ISAba1-activated blaOXA-51-like genes were prevalent among the carbapenem-resistant A. baumannii isolates. CONCLUSION: The class D beta-lactamase genes of A. baumannii were distributed nationwide in non-tertiary Korean hospitals.
Acinetobacter Infections/epidemiology/*microbiology ; Acinetobacter baumannii/classification/*genetics ; Anti-Bacterial Agents/therapeutic use ; Bacterial Typing Techniques ; Carbapenems/*therapeutic use ; DNA, Bacterial/analysis ; *Drug Resistance, Bacterial ; Hospitals ; Humans ; Microbial Sensitivity Tests ; Molecular Epidemiology ; Multilocus Sequence Typing ; Polymerase Chain Reaction ; Prevalence ; Republic of Korea ; beta-Lactamases/genetics