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

OBJECTIVETo investigate antibiotic resistance and carriage class 1 and 2 integrons in clinical isolates of Acinetobacter baumannii (A. baumannii) from Tehran, Iran.

METHODSAntimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute. The presence of integrons was investigated by PCR using specific primers.

RESULTSAmong isolated A. baumannii strains, 82% were multidrug resistant, 27 samples (54%) were resistant to three or more than three antibiotics and 16 samples (32%) showed resistance to two antibiotics. Integrons were detected from 44 of 50 isolates (88%), with classes 1 and 2 being observed in 42% (21/50) and 82% (41/50) of isolates, respectively. Integron-positive A. baumannii isolates showed higher antibiotic resistance than integron-negative isolates and all showed a multidrug-resistant phenotype.

CONCLUSIONSOur findings show that classes 1 and 2 integrons, and especially classes 2 integrons are widely disseminated among A. baumannii strains isolated from Tehran and these structures are playing a major role in the acquisition of multidrug resistance in these strains. So monitoring of drug resistance with investigating carriage class 1 and 2 integrons is very important to plan specific infection control measures due to multidrug resistance A. baumannii in Iran hospitals.

Acinetobacter baumannii ; drug effects ; genetics ; Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Integrons ; genetics ; Iran ; Microbial Sensitivity Tests

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

The worldwide use of antimicrobials in different fields has created enormous pressure for the selection of resistance among opportunistic bacterial pathogen. One hundred four E. coli isolates were collected and identified from swine with diarrhea in Korea during the period of 2002. The isolates showed highly resistant to streptomycin (99. 0%), tetracycline (97. 1%), neomycin (91. 3%)and carbenicillin (84. 6%)in antimicrobial susceptibility test. Moreover, all of the isolates showed multiple antimicrobial resistant to more than 3, and 85%of them were resistant to more than 7 of total 14 antimicrobial agents. In comparison with isolates in 1998, resistance to antimicrobials was more frequent among the isolates in 2002. Presence of class 1 integrons was investigated through amplification of the gene with PCR, and could be classified 8 groups by pattern of 4 different amplicons. Class 1 integrons were observed in 67 strains (64. 2%)of E. coli from swine in Korea. One and 1. 6 kbp of amplicons were revealed to contain aadA1 and aadB-aadA1 gene cassettes respectively. Two kbp of amplicon had three different gene cassettes, dhfrXII-orfF-aadA2, and 3. 0 kbp of amplicon includes aadB-cmlA1 gene cassettes.
Animals ; Anti-Bacterial Agents ; Diarrhea/microbiology/veterinary ; Drug Resistance, Multiple, Bacterial/*genetics ; Escherichia coli/*drug effects/genetics ; Escherichia coli Infections/microbiology/*veterinary ; Integrons/*genetics ; Swine ; Swine Diseases/*microbiology

OBJECTIVETo investigate the relationship between the drug resistance of Pseudomonas aeruginosa (PA) isolated from burn patients wounds and its mobile genetic elements, including plasmid, transposon, and integron.

METHODSThirty-two strains of PA were isolated from wounds exudate of hospitalized burn patients in Ningbo No. 2 Hospital. PA drug sensitivity was determined using GNS-448 drug sensitivity card and K-B tests. The genetic markers of plasmid, transposon and integron including traA, traF, tnpA, tnpU, merA, int I 1 were amplified by PCR and verified by gene sequencing.

RESULTSDrug resistant rate of 32 PA strains to gentamicin, amikacin, cefoperazone/sulbactam, ciprofloxacin was 43.7%, 32.0%, 46.8%, 49.9%, respectively. PA drug resistant rates to piperacillin, cefotaxime, ceftazidime, cefepime, aztreonam, piperacillin/tazobactam, levofloxacin, imipenem and meropenem were all above 56.0%. Seventeen out of 32 PA strains were found to carry transposon and (or) integron genetic markers. One strain was positive for both tnpA and merA, 8 strains were positive for both merA and int I 1, 1 strain was only positive for tnpA, 2 strains were only positive for merA, and 5 strains were positive for int I 1 only.

CONCLUSIONSPA isolated from burn wounds of hospitalized patients in Ningbo No. 2 Hospital is seriously drug resistant, which may relate with its high positive rate of mobile genetic elements of transposon and (or) integron.

Anti-Bacterial Agents ; pharmacology ; Burns ; microbiology ; DNA Transposable Elements ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Integrons ; Microbial Sensitivity Tests ; Plasmids ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification

OBJECTIVETo investigate the characteristic of integrons and the relationship between integrons and antimicrobial resistance in Shigella spp.

METHODSNinety Shigella strains (83 S. flexneri and 7 S. sonnei) were isolated from the stools of patients in China. Susceptibility to 8 antimicrobials was tested for all isolated strains. PCR, RFLP and sequencing analysis of integrons were applied to all of them.

RESULTSHigh prevalence of multi-drug resistance (95.6%) was identified. Of the isolates 79 (87.8%) carried integrase genes of class 1 integron (3.3%), class 2 integron (10.0%) or both (74.4%). No intI3 was detected in the tested isolates. The prevalence of intI2 was significantly higher in isolates with multi-drug resistance to at least 3 antibiotics than that in isolates with resistance to 2 and less antibiotics (P<0.05). Gene cassettes dfrA17-aadA5, dfrA12-orfF-aadA2 of class 1 integron and dfrA1-sat1-aadA1 of class 2 integron were identified.

CONCLUSIONThe class 2 integron may play a role in the emergence of multi-drug resistance in Shigella spp.

Base Sequence ; China ; DNA Primers ; Drug Resistance, Microbial ; Drug Resistance, Multiple ; Integrons ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Shigella ; drug effects ; genetics

Antibacterial drugs are one of the most important therapeutic agents of bacterial infections but multidrug resistant Escherichia coli (MDREC) is an increasing problem worldwide. Major resistance mechanism of MDREC is horizontal gene transfer of R plasmids harboring integrons, which the integron integrase (IntI) catalyzes gene cassette insertion and excision through site specific recombination. In this study, resistance profiles of integron harboring E. coli isolated in Korea and the genetic environments of integron gene cassettes were analyzed by PCR and direct sequencing to clarify the mechanisms of spread of integron harboring E. coli. Resistance rates of integron harboring E. coli, including β-lactams, aminoglycosides, and fluoroquinolones and MDR frequencies were significantly higher than that of E. coli without integron (p < 0.01). Majority (80%) of integron harboring E. coli showed resistance transfer by conjugation. Most (80%) of E. coli had dfrA17-aadA5 cassette array and PcH1 hybrid promoter; 16.7% of E. coli had dfrA12-orfF-aadA2 cassette array and PcW promoter. The higher prevalence of weak Pc variants among most (96.7%) of integron harboring MDREC suggests that a flexible cassette array is more important than enhanced expression. All the integrons had LexA binding motif suggests that SOS responses control the expression of these integrons. In conclusion, the genetic bases of integrons were diverse, and the spread and the expression of prevalent gene cassette arrays may be deeply related with strengths of Pc promoters in integrons. These informations will provide important knowledge to control the increase of integron harboring MDREC.
Aminoglycosides ; Bacterial Infections ; Escherichia coli ; Escherichia ; Fluoroquinolones ; Gene Transfer, Horizontal ; Integrases ; Integrons ; Korea ; Polymerase Chain Reaction ; Prevalence ; R Factors ; Recombination, Genetic ; SOS Response (Genetics)

BACKGROUND: Stenotrophomonas maltophilia is a gram-negative bacillus and a nosocomial pathogen in immunocompromised patients. Trimethoprim/sulfamethoxazole (TMP/SMX) is the drug of choice for treating S. maltophilia infection; however, resistance to TMP/SMX is increasing. In this study, we investigated the relationship between the incidence of TMP/SMX resistance and the presence of sul genes and mobile elements. METHODS: A total of 120 S. maltophilia isolates were collected from 3 university hospitals between April 2007 and April 2009. Antimicrobial susceptibilities were determined using the disk diffusion method. PCR and DNA sequencing were conducted for the detection of sul1, sul2, class 1 integron, and ISCR2 element. Repetitive extragenic palindromic sequence-based PCR (REP-PCR) was carried out to evaluate the genetic relatedness. RESULTS: The TMP/SMX-resistant (R) isolates harbored a significantly higher proportion of sul1 gene and class 1 integron than TMP/SMX-susceptible (S) isolates (P<0.001). Seventeen of 28 isolates with sul1 also had a class 1 integron, but none of the isolates without sul1 had a class 1 integron. The identified gene cassettes within class 1 integrons include aacA4, aadA1, aac6'-II, and qac. None of the 120 isolates carried sul2, glmM, or ISCR2 element. REP-PCR did not show any genetic relatedness among the isolates. CONCLUSIONS: In Korea, the resistance of S. maltophilia isolates to TMP/SMX is due to sul1 within a class 1 integron rather than to sul2. The class 1 integron also harbors multiple antibiotic resistance genes in addition to sul1, and therefore it could mediate multidrug resistance in S. maltophilia.
Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins/genetics ; Carrier Proteins/genetics ; DNA, Bacterial/genetics ; Disk Diffusion Antimicrobial Tests ; Drug Resistance, Multiple, Bacterial/genetics ; Humans ; Integrons/genetics ; Polymerase Chain Reaction ; Stenotrophomonas maltophilia/*drug effects/*genetics/isolation &purification ; Trimethoprim-Sulfamethoxazole Combination/*pharmacology