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Novel Class 1 Integrons in Multi-drug Resistant Isolates from Eastern China.

ABSTRACT: Integrons are mobile genetic elements able to capture, express and excise resistance genes, playing an important role in the spread of bacterial resistance. The present study was to investigate the occurrence and diversity of integrons in 120 clinical multi-drug resistant Gram-negative isolates from eastern China. Screening of integrons was performed by PCR and gene cassettes were further characterized by PCR-RFLP and sequencing. Class 1 integrons were detected in 70.8 % of isolates and no class 2 and class 3 integrons were detected in any isolates. A total of 19 resistant gene cassettes were identified, four representative of novel gene cassettes: an aacA3 variant (aacA3c), an aacA4 variant (aacA4'-17), a bla OXA variant (bla OXA-251 ), and a catB8 gene cassette interrupted by an insertion sequence IS10 (catB8::IS10). In addition, 14 cassette arrays were detected, including three novel integrons: gcuD1-aacA4'-17-gcu38B-catB8::IS10 (In712), aacA3c-aadA13-bla OXA-251 (In713) and dfrA1-gcu37-aadA5 (In714). The presence of novel integron structures in clinical isolates suggests hospital environments may favor the formation of novel combination of gene cassettes. Moreover, the high prevalence of integrons in multi-drug resistant isolates highlights the urgent need to employ effective means to avoid dissemination of drug-resistant bacteria.

SUBMITTER: Sun G

PROVIDER: S-EPMC4188487 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature

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Novel Class 1 Integrons in Multi-drug Resistant Isolates from Eastern China.

Sun Guangming G Yi Maoli M Shao Chen C Ma Jin J Zhang Qiang Q Shao Shihe S

Indian journal of microbiology 20131204 2

Integrons are mobile genetic elements able to capture, express and excise resistance genes, playing an important role in the spread of bacterial resistance. The present study was to investigate the occurrence and diversity of integrons in 120 clinical multi-drug resistant Gram-negative isolates from eastern China. Screening of integrons was performed by PCR and gene cassettes were further characterized by PCR-RFLP and sequencing. Class 1 integrons were detected in 70.8 % of isolates and no class ...[more]

PMID: 25320427

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Project description:Purpose:The integrons, as the mobile exogenous elements, play a prominent role in the spreading of antimicrobial resistance genes from Pseudomonas aeruginosa clinical isolates to other bacteria. This study aimed to investigate the frequency of class 1 integrons andresistance gene cassettes carrying by them in clinical isolates as well as multidrug resistant P. aeruginosa. Materials and Methods:A total of 100 clinical isolates of P. aeruginosa were collected from 5 hospitals in Mazandaran province, north Iran. The antibiotic susceptibility pattern of the isolates was evaluated using the disk agar diffusion method. Genomic DNAs were extracted and then the presence of class 1 integrons was detected by the PCR test. All PCR products of the positive isolates were sequenced for the detection of resistance gene cassettes by the Sanger method. Results:Forty-one percent of the clinical isolates were multi-drug resistant. Also, 42% of the isolates were contained class 1 integron, and 61.9% of the integron positive isolates were detected as MDR. We detected 10 different gene cassettes sizing from 0.6 to 3.5 kb in the present study. The sequencing analysis of the internal variable regions of the class 1 integrons showed that the 0.75 kb gene cassette (aadB) was the most frequent resistance gene (54.76%) among all clinical isolates, as well as the MDR isolates. Other resistance genes detected in this study were included: aadA6-orfD (35.71%), aacA4-bla OXA-10 (21.42%), aadB-aacA4-bla OXA-10 (19.04%), bla OXA-10-aacA4-VIM1 (11.9%), aacA4-catB10 (7.14%), aacA5-aadA1-cmlA5 (7.14%), bla OXA31-aadA2 (4.76%), and aac(3)-Ic-aacA5-cmlA5 (4.76%). To the best of our knowledge, bla OXA-10 -aacA4-VIM1 cassette array is detected for the first time in this study. Conclusion:The treatment of infections caused by P. aeruginosa in this region of Iran is a major problem due to the high prevalence of class 1 integrons. It seems that the high prescription of beta-lactams and aminoglycosides for the treatment of these infections may be replaced by other combination therapy stewardships.

Project description:The aim of this multiple-hospital study was to investigate the prevalence of integrons in multidrug-resistant Acinetobacter baumannii (MDRAB) in Eastern China, and characterize the integron-integrase genes, so as to provide evidence for the management and appropriate antibiotic use of MDRAB infections.A total of 425 clinical isolates of A. baumannii were collected from 16 tertiary hospitals in 11 cities of four provinces (Fujian, Jiangsu, Zhejiang and Shandong) from January 2009 to June 2012. The susceptibility of A. baumannii isolates to ampicillin/sulbactam, piperacillin/tazobactam, ceftazidime, ceftriaxone, cefepime, aztreonam, meropenem, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin, sulfamethoxazole/trimenthoprim, minocycline and imipenem was tested, and integrons and their gene cassettes were characterized in these isolates using PCR assay. In addition, integron-positive A. baumannii isolates were genotyped using pulsed-field gel electrophoresis (PFGE) assay, and intI1 gene cassette was sequenced.intI1 gene was carried in 69.6% of total A. baumannii isolates, while intI2 and intI3 genes were not detected. The prevalence of resistance to ampicillin/sulbactam, piperacillin/tazobactam, ceftazidime, ceftriaxone, cefepime, aztreonam, imipenem, meropenem, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin and sulfamethoxazole/trimenthoprim was significantly higher in integron-positive A. baumannii isolates than in negative isolates (all p values <0.05), while no significant difference was observed in the prevalence of minocycline resistance (p > 0.05). PFGE assay revealed 27 PFGE genotypes and 4 predominant genotypes, P1, P4, P7 and P19. The PFGE genotype P1 contained 13 extensive-drug resistant and 89 non-extensive-drug resistant A. baumannii isolates, while the genotype P4 contained 34 extensive-drug resistant and 67 non-extensive-drug resistant isolates, appearing a significant antimicrobial resistance pattern (both p values <0.05). Sequencing analysis revealed two gene cassette assays of aacA4-catB8-aadA1 and dfrXII-orfF-aadA2 in MDRAB isolates.The results of this study demonstrate a high prevalence of class 1 integrons in MDRAB in Eastern China, and a greater prevalence of antimicrobial resistance in intI1 gene-positive MDRAB isolates than in negative isolates. Four predominant PFGE genotypes are identified in intI1 gene-positive MDRAB isolates, in which P4 is an epidemic PFGE genotype in Fujian Province, and it has a high proportion of extensive drug resistant A. baumannii. The gene cassette dfrXII-orfF-aadA2 is reported, for the first time, in A. baumannii strains isolated from Fujian Province, Eastern China.

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Novel Class 1 Integrons in Multi-drug Resistant Isolates from Eastern China.

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Novel Class 1 Integrons in Multi-drug Resistant Isolates from Eastern China.

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