No abstract available.
Integrons*

No abstract available.
Integrons*

The class 1 integron and complex gene cassettes among different species of clinical isolates in northern China were characterized in this study. 383 clinical isolates were obtained from northern China, and class 1 integrons containing gene cassettes widely distributed among gram negative clinical isolates was observed. We find that the class 1 integron showed positive correlation with multidrug resistance phenotype of gram negative bacteria. In addition, we find that isolates belonged to one species harbored different types of gene cassette arrays, while same types of gene cassette arrays were observed in different species of isolates. The diversity of gene cassette arrays among the isolates indicated the complexity of multidrug resistance in clinical isolates in northern China.
Bacteria ; classification ; genetics ; isolation & purification ; China ; Hospitals, Public ; Humans ; Integrons ; genetics

Drug Resistance, Bacterial ; genetics ; Food Microbiology ; Gram-Negative Bacteria ; genetics ; isolation & purification ; Integrons ; Japan ; Seafood ; microbiology

Objective To explore the effects of Scutellaria baicalensis on activity and biofilm formation of Klebsiella pneumonia (Kp).Methods The broth and agar dilution Methods were carried out to determine minimum inhibitory concentration and minimum bactericidal concentration of Scutellaria baicalensis for TW518. VITEK-32 system was used to assay TW518 susceptibility to antibiotics. Kp biofilms were formed in vitro and stained with BacLight Live/Dead stain. The class integron geneⅠ1 mRNA expression was analyzed with RT-PCR.Results The minimum inhibitory concentration of Scutellaria baicalensis on TW518 identified as a Kp colony was 32 mg/ml, and minimum bactericidal concentration was 64 mg/ml. Scutellaria baicalensis and broad-spectrum penicillin, cephalosporin, quinolones, or beta-lactamase had synergistic bactericidal effects. Biofilm formation activity of Kp treated with Scutellaria baicalensis was significantly lower than that of the control group. And class integron geneⅠ1 mRNA expression of TW518 was significantly inhibited by Scutellaria baicalensis.Conclusions Scutellaria baicalensis has sterilization effect on Kp, and Scutellaria baicalensis could effectively inhibit Kp biofilm formation with prolonged treatment. Scutellaria baicalensis might inhibit Kp biofilm formation through down-regulating integron geneⅠ1 expression.
Biofilms ; drug effects ; Integrons ; drug effects ; Klebsiella pneumoniae ; drug effects ; physiology ; Microbial Sensitivity Tests ; Scutellaria baicalensis

BACKGROUND: Clinical isolates of AmpC beta-lactamase- producing Enterobacteriaceae were evaluated to determine the prevalence of CTX-M extended-spectrum beta-lactamases (ESBLs) and their genetic environments. METHODS: A total of 250 non-duplicate isolates of Eneterobacter aerogenes, E. cloacae, Citrobacter freundii, Serratia marcescens and Morganella morganii were collected at a Korean hospital. ESBL production was determined by double disk synergy test. For ESBL producers, bla genes were sequenced and blaCTX-M environment was characterized by PCR mapping and sequencing. RESULTS: Among the 250 isolates 29 (11.6%) produced ESBL, and 14 of the 29 isolates produced CTX-M ESBLs, including CTX-M-9 by 8 isolates, CTX-M-3 by 4 isolates, CTX-M-12 by 1 isolate, and CTX-M-14 by 1 isolate. ISEcp1 was present upstream of blaCTX-M-3, 12, and 14. Three of the four CTX- M-3 producers had the same genetic environment (pemK-ISEcp1-blaCTX-M-3-orf477-mucA). An IS903-like element was found downstream of blaCTX-M-14. ISCR1 was identified upstream of blaCTX-M-9 and ISCR1 and blaCTX-M-9 were located on sul1-type class 1 integron. The variable region between the 5'-CS and the first 3'-CS contained dfrA16 and aadA2. Its structure was similar to that of In60, but our isolates did not have IS3000 or second 3'-CS. CONCLUSION: CXT-M type ESBL was prevalent in AmpC beta-lactamase-producing Enterobacteriaceae, particularly E. cloacae. blaCTX-M genes were associated with ISEcp1 or ISCR1. This is the first report on the genetic environment of blaCTX-M in Korean isolates.
beta-Lactamases ; Citrobacter freundii ; Cloaca ; Enterobacteriaceae ; Integrons ; Korea ; Morganella morganii ; Polymerase Chain Reaction ; Prevalence ; Serratia marcescens

BACKGROUND: Metallo-beta-lactamase-mediated carbapenem resistance has been increasingly reported in Pseudomonas, Acinetobacter and other Gram-negative bacilli (GNB) in many countries. A few studies showed highly variable structure of MBL-gene cassette-carrying integrons. The aim of this study was to determine the structure of blaVIM-2-carrying integrons in Pseudomonas and Acinetobacter. METHODS: blaVIM-2-carrying GNB were isolated at a Korean hospitals during the years 1995-1999 and 2005. The size of blaVIM-2-carrying integrons was estimated by the PCR products. Representative integrons were sequenced by the dideoxy-chain termination method. The MICs of antimicrobial agents were tested by the CLSI agar dilution methods. RESULTS: During the years 1995-1999 and 2005, the approximate size of the blaVIM-2-carrying class 1 integrons was 3-7 kb in 35 Pseudomonas isolates and 3-5 kb in 24 Acinetobacter isolates. The integrons carried one-five resistance gene cassettes in addition to the blaVIM-2 cassette. Other resistance gene cassettes found were blaOXA-1, aacA1, aac(6')-I, and aac(6')-II. Interestingly, sequences homologous to part of a putative class II intron were inserted into the recombination site of the last cassette in four of nine integrons. The class 1 integron from P. aeruginosa isolates had fused orf/IntI1 in a downstream leftward inverted repeat (IRi). CONCLUSION: According to period, the size and structure of blaVIM-2-carrying integrons are quite variable, but an identical one is also present in a different genus, indicating high mobility of the blaVIM-2 cassette and horizontal transfer of the whole integron. We suggest that the class 1 integron containing the blaVIM-2 gene is spreading horizontally among Gram-negative bacilli and is undergoing continuous development in Korea.
Acinetobacter ; Agar ; Anti-Infective Agents ; Integrons ; Introns ; Korea ; Lifting ; Polymerase Chain Reaction ; Pseudomonas ; Recombination, Genetic

OBJECTIVES: Integrons are thought to play an important role in the spread of antibiotic resistance. This study investigates class 1 and 2 integron-positive methicillin-resistant coagulase-negative staphylococci strains isolated in Iran and characterizes their patterns of antimicrobial resistance. METHODS: Hundred clinical isolates of coagulase-negative staphylococci were characterized for integron content and staphylococcal cassette chromosome mec (SCCmec) type. RESULTS: Sixteen isolates carried class 1 (intI1) integrons and four isolates carried class 2 (intI2) integrons. One resistance gene array was identified among the class 1 integrons (aadA1 cassette). The distribution of SCCmec types in 50 methicillin-resistant coagulase-negative staphylococci strains showed that SCCmec types III and V dominated among the tested strains. CONCLUSION: This is the first report of methicillin-resistant coagulase-negative staphylococci strains that carry two mobile genetic elements, including class 1 and 2 integrons and SCCmec, in Iran.
Coagulase* ; Drug Resistance, Microbial ; Integrons* ; Interspersed Repetitive Sequences ; Iran ; Methicillin Resistance*

OBJECTIVETo investigate the drug resistance of enteric bacilli and its relation to the drug resistance gene cassette in the variable region and molecular evolution of class-I integron.

METHODSK-B assay was applied to measure the drug resistance of E.coli, E.cloacae and A.baumannii isolated against twelve antibiotics. The class-I integron and drug resistance gene cassettes in the variable region of the integron were detected by PCR and sequencing of amplification products. The molecular evolution of drug resistance genes in the class-I integrons was analyzed using Clustal X and MEGA software.

RESULTS54.2%-100% of A.baumannii isolates were resistant to the penicillin and cephem antibiotics, while E.coli and E.cloacae isolates had resistance rates of 41.6%-62.5% to cephem antibiotics. 62.5%(15/24) of E.coli, 67.9%(19/28) of E.cloacae and 83.3%(20/24) of A.baumannii isolates were positive for class-I integrons. 81.5% (44/54) of class-I integrons showed 4 different single band spectrums and the other class-I integrons displayed 3 different double band spectrums. In the drug resistance gene cassettes in variable regions of class-I integrons there were 7 types in 4 groups of drug resistance genes, including aac(6'), sad(3"), aad(2"), cat(4') and dfr (types 7, A13 and 15), which induced the resistance to aminoglycosides and sulfamido antibiotics and chloromycin. The class-I integrons in the isolates might be divided into 4 molecular evolution groups according to the diversity of dihydrofolate reductase encoding gene sequences.

CONCLUSIONThe enteric bacilli have a high drug resistance and frequently carry class-I integrons with 7 drug resistance gene cassettes which present 4 different evolutionary pathways.

Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Enterobacteriaceae ; drug effects ; genetics ; Evolution, Molecular ; Integrons ; genetics

Objective The aim of our study is to investigate the prevalence of Carbapenem-resistant Klebsiella pneumoniae (CRKP) and the genetic characteristics of the class 1 integron in CRKP on multi-drug resistance.Methods Clinical Klebsiella pneumoniae strains were collected from multiple departments of a hospital in central China. CRKP strains were identified among the isolates, and antibiotics susceptibility of CRKP strains was analyzed. The polymerase chain reaction (PCR) was adopted to amplify the class 1 integron variable area. The integron genetic structure was analyzed with enzyme digestion and DNA sequencing technology. The relation between class 1 integron and drug resistance was analyzed statistically.Results Totally 955 strains of Klebsiella pneumoniae were isolated from varied sites of the hospital, and 117(12.3%) of them were identified as CRKP, with a separation rate of 8.9% (26/292) in 2013, 11.3% (38/336) in 2014 and 16.2% (53/327) in 2015, which shows an increasing trend by year. 44.4% (52/117) of CRKP strains were separated from specimen of ICU, and 61.5% (72/117) were from sputum. Over 95% CRKP strains were resistant to ampicillin/sulbactam, aztreonam, imipenem, meropenem, ceftazidme, cefotaxime, cefepime,and piperacillin, while relatively low resistant rates were found in tigecycline (12.8%) and colistin (35.9%). The class 1 integron was detected in 77.8% (91/117) of CRKP strains. Class 1 integron of CRKP was significantly correlated with the antibiotic resistance to the tobramycin, gentamicin and amikacin (all P<0.01). The gene cassette analysis of variable area of class 1 integron showed that aadA2 accounts for 64.8% (59/91), aacA4-catB8-aadA1 23.1% (21/91), and aadA2-dfrA25 12.1% (11/91).Conclusions CRKP has an increasing trend in a clinical setting in China, and most of them were resistant to multiple antibiotics. Class 1 integron in CRKP has strong ability to capture the genes resistant to aminoglycosides antibiotics from environment, with the aadA2 gene as the most popular one.
Anti-Bacterial Agents ; pharmacology ; Carbapenems ; pharmacology ; Drug Resistance, Bacterial ; Integrons ; Klebsiella pneumoniae ; drug effects ; genetics ; isolation & purification