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Background China is a big country in the production and use of antibiotics. The abuse of antibiotics enables bacteria in water environment to acquire resistance, and promotes the generation and spread of antibiotics resistance genes (ARGs). The problem of antibiotic-resistant bacteria is increasingly serious and has become a public security issue of global concern. Water environment is a huge reservoir of antibiotics and ARGs. It is of great significance to study the pollution of antibiotics and ARGs in water to protect water sources and optimize the biosecurity of drinking water. Objective To evaluate the detection of antibiotics and ARGs in typical water sources, and to explore the relationship between antibiotics and ARGs. Methods Water samples were collected in Heilongjiang, Liaoning, and Hubei provinces during the wet season (from August to October) in 2020. Ten water samples were collected from each of the three places, and a total of 30 water samples were collected in this study. Five kinds of antibiotics, including macrolides, quinolones, sulfonamides, tetracycline, and β-lactam, were detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The integron (Intl1), 16S rRNA, and 6 kinds of ARGs were detected by quantitative real-time PCR (qPCR). The ARGs include one macrolide ARGs (ermB), one β-lactam ARGs (blaTEM), two tetracycline ARGs (tetC, tetQ), and two sulfonamide ARGs (sul1, sul2). Results The types of detected antibiotics varied by the three regions, and the concentration ranges of the same antibiotics varied by the three regions (P<0.05). The concentration ranges of selected five kinds of antibiotics were 0.11-418.80 ng·L−1 in region A, 0.12-23.23 ng·L−1 in region B, and 4.69-285.75 ng·L−1 in region C, respectively. The detection rates of all six ARGs were 100%. The absolute abundance of ARGs in region A ranged from 22.56 to 94355.91 copies·mL−1, that in region B ranged from 27.99 to 80584.32 copies·mL−1, and that in region C ranged from 41.99 to 111068.19 copies·mL−1. The absolute abundance of blaTEM was higher among the ARGs, followed by sul1 and sul2. In addition, the absolute abundance of Intl1 was also at a high level. The results of correlation analysis showed that the abundance of ARGs was positively correlated with each other. There was no correlation between specific antibiotics and corresponding ARGs. There was a positive correlation between Intl1 and sul1 or sul2 (P<0.05). Conclusion The types and concentrations of antibiotics and the abundance of ARGs in source water vary greatly in the study areas. The association between antibiotics and ARGs is uncertain. Intl1 may play an important role in the horizontal transfer of sulfonamide resistance genes.
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Objective:To investigate the distribution of integrons and plasmid-mediated quinolone resistance (PMQR) genes in clinical isolates of Klebsiella aerogenes and to analyze the relationship between integrons and bacterial resistance to antimicrobial agents. Methods:Ninety-one Klebsiella aerogenes strains isolated from clinical samples in the Fengxian District Central Hospital from November 2015 to March 2021 were used in this study. Class 1 and class 2 integron-integrase genes ( intI1 and intI2) and PMQR genes were screened by PCR. The types of promoters and gene cassette arrays of variable regions were determined by sequencing. Besides, the relationship between integrons and antimicrobial resistance was analyzed. Results:The resistance rate of the 91 Klebsiella aerogenes isolates to aztreonam was more than 40.00% and the resistance rates to other commonly used antimicrobial agents were less than 35.00%. Among the 91 isolates, 30 carried the intI1 gene, while none of them carried the intI2 gene. Seven class 1 integron gene cassette arrays of variable regions were detected and the gene cassette array of aac(6′)-11 C- ΔereA2- IS1247- aac3- arr- ΔereA2 was detected in Klebsiella aerogenes. PcH1 with weak activity was the predominant variable region promoter of class 1 integrons. The detection rates of intI1-positive and intI1-negative isolates in ICU, neurosurgery and other clinical departments were statistically different ( P<0.05). The resistance rate of intI1-positive isolates to some commonly used antibiotics was significantly higher than that of intI1-negative isolates ( P<0.05). qnrS gene was the prevalent PMQR gene. The detection rates of integrons and PMQR genes in Klebsiella aerogenes isolates was low except for the strains isolated in 2016. Conclusions:Antimicrobial resistance in Klebsiella aerogenes was closely related to integrons. The distribution of integrons in Klebsiella aerogenes strains isolated from different clinical departments was different, and the monitoring of drug-resistant strains should be strengthened in ICU and neurosurgery. The resistance to quinolones in Klebsiella aerogenes strains in this region was mainly related to qnrS gene.
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Objective To investigate the drug resistance characteristics and epidemic trend of Escherichia coli in Anning, Yunnan, and to provide a reference for clinical rational use of antibiotics. Methods A total of 376 strains of Escherichia coli were isolated from June 2018 to June 2019 from Kungang Hospital of Yunnan Province. The ESBLs producing strains were screened by double disk method and the sensitivity of ESBLs to antibiotics was detected by K-B method. The genotyping of ESBLs strains and the class I, II and III integrase genes in integron 3' and 5' conservative regions was conducted using polymerase chain reaction (PCR). Results The detection rate of ESBLs producing Escherichia coli was 53.19% (200/376). ESBLs-producing Escherichia coli had a low resistance rate to carbapenem antibacterial drugs with a relatively high sensitivity. The resistance rates to amikacin and piperacillin were 7.50% and 12.50% respectively, which had good antibacterial activity. The resistance rate to other antibiotics was high. There were 74.00% (148/ 200) of ESBLs-producing Escherichia coli carrying CTX-M gene, 34.50% (69/200) carrying TEM genes, and 1.00% (2/200) of strains carrying SHV genes. In addition, there were 9.00% (18/200) of strains carrying both CTX-M and TEM genes, and 0.50% (1/200) of strains carrying both CTX-M and SHV genes. The detection rate of integrons accounted for 37.00% (74/200), all of which were class I integrons. Conclusion The prevalence of ESBLs-producing Escherichia coli was relatively high in Anning, Yunnan. ESBLs-producing Escherichia coli showed a trend of multi-drug resistance. The genotype was mainly CTX-M, and the integron was classified as class I.
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Background: Acinetobacter baumannii is anopportunistic pathogen associated with nosocomialinfections. Extensive use of quinolones has resulted inan increase of resistance in this organism worldwide.Aim and Objectives: To study the association betweenPMQR genes, integron carriage as well as the possiblerole of AdeABC efflux pump in ciprofloxacinresistance as well as multidrug resistance in clinicalisolates of A. baumannii. We studied the presence ofPlasmid-Mediated-Quinolone Resistance (PMQR);AdeABC efflux pump genes and integron carriage inIntensive Care Unit (ICU) isolates of A. baumannii.Material and Methods: Fifty six non-duplicate clinicalisolates of A. baumannii were obtained from twoth th hospital ICUs in Tehran from March 5 2014 to July 202015. Susceptibility to 10 antibiotics was determinedby disc diffusion. Presence of PMQR (aac(6')-Ib-cr,qnrA, qnrB, qnrC, qnrD and qnrS), adeABC efflux andclass I and II integron genes were detected byPolymerase Chain Reaction (PCR). Results: Allisolates were Multidrug-Resistant (MDR) amongwhich, qnrB and aac(6')-Ib-cr were detected in 7.1%and 26.8% of the isolates, respectively. However, qnrA,qnrC, qnrD and qnrS were not observed. Presence ofadeA and adeB was observed in 100% and adeC in73.2% of the isolates. Overall, integron carriage wasobserved in (94.6%) of the isolates including qnrBpositive and 73.3% of the aac(6')-Ib-cr carryingisolates. Conclusion: Our results show that quinoloneresistance is not associated with PMQR genes. On theother hand, the AdeABC efflux pump is clearlyresponsible for MDR in our A. baumannii isolates including resistance to quinolones. No association wasfound between PMQR and integron carriage.
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Objective To investigate the distribution of integrons in clinical isolates of carbapen-em-resistant Acinetobacter baumannii and their relationships to bacterial resistance to antimicrobial agents.Methods A total of 115 carbapenem-resistant Acinetobacter baumannii strains were isolated from clinical samples of patients from January to October, 2017. Phoenix 100 automatic microbiological analyzer was used for antimicrobial sensitivity analysis. Classes 1 and 2 integrase genes and carbapenemase-encoding genes, bla IMP , blaVIM , blaKPC , blaNDM and blaOXA-23 , were screened by PCR. The variable regions of integrons were amplified by long fragment PCR. The types of promoters and gene cassette arrays of variable regions were de-termined by sequencing and overlap PCR. Relationships between integrons and antimicrobial resistance were analyzed. Results The 115 isolates of carbapenem-resistant Acinetobacter baumannii were resistant to most commonly used antimicrobial agents, but sensitive to polymyxin E. All of the isolates carried blaOXA-23 gene and none of them were positive for blaIMP , blaVIM , blaKPC or blaNDM gene. Class 1 integrase gene intI1 was de-tected in 40 isolates (34. 8％ ), while class 2 integrase gene intI2 was not detected. Two gene cassette ar-rays of variable regions, aacA4-catB8-aadA1 (39 isolates) and aacC1-gacP-gacQ-aadA1a (23 isolates), were detected in intI1-positive isolates. Twenty-two isolates carried both aacA4-catB8-aadA1 and aacC1-gacP-gacQ-aadA1a. The upstream promoters of the variable regions were relatively strong promoters, PcH2 and PcS. The gene cassettes of the variable regions endowed bacteria with resistance to chloramphenicol and aminoglycoside antibiotics. The resistance rate of class 1 integron-positive isolates to compound sulfamethox-azole was higher than that of negative strains. However, their resistance rate to ampicillin/sulbactam was lower than that of negative strains. Conclusions Antimicrobial resistance in carbapenem-resistant Acineto-bacter baumannii was serious. Carbapenem resistance was associated with blaOXA-23 gene. The types of pro-moters of variable regions in class 1 integrons were all relatively strong promoters. Class 1 integrons were closely related to sulfonamides resistance.
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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.
Subject(s)
Aminoglycosides , Bacterial Infections , Escherichia coli , Escherichia , Fluoroquinolones , Gene Transfer, Horizontal , Integrases , Integrons , Korea , Polymerase Chain Reaction , Prevalence , R Factors , Recombination, Genetic , SOS Response, GeneticsABSTRACT
Introdução: Efluentes hospitalares representam riscos à saúde pública e ambiental devido à presença de microrganismos patogênicos, drogas e produtos químicos. Pseudomonas aeruginosa é um patógeno oportunista frequentemente encontrado no ambiente hospitalar. Objetivo: Avaliar o resistoma de isolados de P. aeruginosa da estação de tratamento de esgoto hospitalar (ETEH) de um complexo hospitalar na cidade do Rio de Janeiro. Método: Vinte isolados dos cinco estágios da ETEH foram identificados como P. aeruginosa pelo sequenciamento do gene 16S rRNA. A suscetibilidade aos antibióticos foi determinada segundo o CLSI e os genes qacEΔ1 e sul1 foram detectados pela PCR. Resíduos de sulfonamidas foram pesquisados por cromatografia líquida de alta eficiência acoplada à espectrometria de massas sequencial. Resultados: Foi demonstrada a presença de sulfametoxazol em nível inferior a 50 ngâL−1, resistência às sulfonamidas (80%) seguida pelas quinolonas (50%) e 13 perfis de suscetibilidade aos antimicrobianos. Os genes qacEΔ1-sul1 foram detectados em 100% dos isolados, sugerindo a presença de integrons de classe 1 em toda a ETEH. Conclusões: Os resultados sinalizaram limitações no tratamento e a propagação de genes de resistência nas etapas da ETEH. Esses dados contribuem com órgãos competentes no desenho de ações preventivas frente aos impactos negativos à saúde pública.
Introduction: Hospital effluents may pose great environmental risk due to the presence of pathogenic microorganisms, drugs and chemical components. Pseudomonas aeruginosa is an opportunistic pathogen frequently found in hospital environment. Objective: To evaluate the resistome of P. aeruginosa from the hospital wastewater treatment plant (HWTP) in a hospital complex of Rio de Janeiro city. Method: Twenty isolates from the five stages of the HWTP were identified as P. aeruginosa by 16S rRNA gene sequencing analysis. Susceptibility to antibiotics was determined according to CLSI and qacEΔ1 and sul1 genes were detected by PCR. Sulphonamide residues were investigated by high performance liquid chromatography coupled to sequential mass spectrometry. Results: The sulfamethoxazole has been demonstrated at a level below 50 ng L-1. Sulfonamide resistance (80%) has been demonstrated followed by quinolone class (50%) and 13 susceptibility patterns to antimicrobials. The qacEΔ1-sul1 genes were detected in 100% of isolates suggesting the presence of class 1 integrons in the whole HWTP. Conclusions: The results signalized limitations of HWTP and propagation of resistance genes in all stages of the HWTP. These data also contribute to the environmental sanitary surveillance in the design of prevention actions against negative impact on the public health.
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Background: Integrons are genetic elements which are known for their role in capturing and spreading of antibiotic resistance determinants among Gram-negative bacilli. So far, there is no study regarding Class 3 integron and their genetic organisation in India. Objective: This study investigates the occurrence of Class 3 integron and their gene cassette array among Escherichia coli. Materials and Methods: In this study, a total of 200 E. coli isolates were collected from indoor and outdoor patients from Silchar Medical College and Hospital during September 2015 to February 2016. Detection of the integrase genes and gene cassettes within the Class 3 integron was performed by polymerase chain reaction which was further analysed by sequencing. Results: Twenty-seven isolates were found to harbour Class 3 integron. Sequencing of the gene cassettes and whole Class 3 integron revealed the presence of nine different types of cassettes array, out of which the arrangement with glycerol kinase gene cassette was found to be the most prevalent. Arrangement with blaCTX-Mgene cassette was also detected in few isolates. Conclusion: This study provides epidemiological profiling of Class 3 integrons in this geographical area. The data generated in this study are helpful in infection control programme, anti-infective research and search for epidemiological markers.
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BACKGROUND: In many developing countries, shigellosis is endemic and also occurs in epidemics and treatment of multidrug-resistant (MDR) isolates are important. The aims of this study were to determine the antimicrobial susceptibility, prevalence of class 1 and 2 integrons and the clonal relatedness of isolates. MATERIALS AND METHODS: Antimicrobial susceptibility tests were performed by disc diffusion method. Polymerase chain reaction (PCR)-sequencing technique was employed for detection and characterization of integrons. The genetic relatedness was evaluated by using enterobacterial repetitive intergenic consensus (ERIC) PCR. RESULTS: There was a high percentage of resistance to trimethoprim-sulfamethoxazole (TMP/SMX) (93.7%), ampicillin (AMP) (87.3%), streptomycin (STR) (84.5%) and tetracycline (TET) (78.9%). Multidrug resistant phenotype was seen in 95.1% of total isolates. Most common MDR profile was TMP/SMX/STR/AMP resistant pattern. Among the 142 Shigella spp. analyzed in this study, 28 isolates were positive for class 1 integron with two types of gene cassette arrays (dfrA17/aadA5 = 31.7% and dfrA7 = 3.8%). The class 2 integron was more frequently detected among the isolates (94.7%) with dfrA1/sat1/aadA1 (69.4%) and dfrA1/sat1 (30.6%) gene cassettes. ERIC-PCR results showed 6, 5, 4 and 3 main genotypes among S. flexneri, S. sonnei, S. boydii and S. dysenteriae isolates, respectively. CONCLUSIONS: Our findings revealed that multidrug resistant Shigella species with high prevalence of class 2 integron were very common in Iran. In addition, ERIC-PCR patterns showed limited variety of clones are responsible for shigellosis in the region of the study.
Subject(s)
Ampicillin , Clone Cells , Consensus , Developing Countries , Diffusion , Dysentery, Bacillary , Genotype , Integrons , Iran , Methods , Phenotype , Polymerase Chain Reaction , Prevalence , Shigella , Streptomycin , Tetracycline , Trimethoprim, Sulfamethoxazole Drug CombinationABSTRACT
BACKGROUND: In many developing countries, shigellosis is endemic and also occurs in epidemics and treatment of multidrug-resistant (MDR) isolates are important. The aims of this study were to determine the antimicrobial susceptibility, prevalence of class 1 and 2 integrons and the clonal relatedness of isolates. MATERIALS AND METHODS: Antimicrobial susceptibility tests were performed by disc diffusion method. Polymerase chain reaction (PCR)-sequencing technique was employed for detection and characterization of integrons. The genetic relatedness was evaluated by using enterobacterial repetitive intergenic consensus (ERIC) PCR. RESULTS: There was a high percentage of resistance to trimethoprim-sulfamethoxazole (TMP/SMX) (93.7%), ampicillin (AMP) (87.3%), streptomycin (STR) (84.5%) and tetracycline (TET) (78.9%). Multidrug resistant phenotype was seen in 95.1% of total isolates. Most common MDR profile was TMP/SMX/STR/AMP resistant pattern. Among the 142 Shigella spp. analyzed in this study, 28 isolates were positive for class 1 integron with two types of gene cassette arrays (dfrA17/aadA5 = 31.7% and dfrA7 = 3.8%). The class 2 integron was more frequently detected among the isolates (94.7%) with dfrA1/sat1/aadA1 (69.4%) and dfrA1/sat1 (30.6%) gene cassettes. ERIC-PCR results showed 6, 5, 4 and 3 main genotypes among S. flexneri, S. sonnei, S. boydii and S. dysenteriae isolates, respectively. CONCLUSIONS: Our findings revealed that multidrug resistant Shigella species with high prevalence of class 2 integron were very common in Iran. In addition, ERIC-PCR patterns showed limited variety of clones are responsible for shigellosis in the region of the study.
Subject(s)
Ampicillin , Clone Cells , Consensus , Developing Countries , Diffusion , Dysentery, Bacillary , Genotype , Integrons , Iran , Methods , Phenotype , Polymerase Chain Reaction , Prevalence , Shigella , Streptomycin , Tetracycline , Trimethoprim, Sulfamethoxazole Drug CombinationABSTRACT
Objective To analyze the structures of atypical class 1 integrons in clinical Proteus isolates. Methods This study included 26 class 1 integron integrase gene-positive clinical Proteus isolates, from which the variable regions of class 1 integrons could not be amplified. Six isolates were chosen from them to amplify the flanking DNA segments of class 1 integron integrase gene using inverse PCR. The se-quences of PCR products were analyzed with BLAST to identify the target homologous sequences as well as their accession numbers in GenBank. Primers for overlap PCR were designed according to the flanking se-quences. Then the 26 clinical Proteus isolates were analyzed with overlap PCR and sequencing analysis. Re-sults The variable regions of class 1 integrons in 25 out of the 26 clinical Proteus isolates were completely or partly identified by using inverse PCR,overlap PCR and sequencing analysis. A gene cassette array of estX-psp-aadA2-cmlA1-aadA1a-qacI-tnpA-sul3 was detected in 22 isolates. The variable regions of class 1 integrons in the other three isolates were identified to be estX-psp-aadA2-cmlA1,dfrA14 and IS26,respectively. All of the 25 isolates lacked the 3'conserved segements in class 1 integron. Conclusion Inverse PCR can be used to analyze the structures of atypical class 1 integrons. Gene cassette psp and gene cassette arrays of estX-psp-aadA2-cmlA1-aadA1a-qacI-tnpA-sul3 and estX-psp-aadA2-cmlA1 in clinical Proteus isolates are reported for the first time.
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Objective To investigate the distribution of integrons and ISCR1 elements in NDM-l-producing Citrobacterfreundii isolates,and analyze the genotypes of these strains to understand their homology.Methods A total of 18 strains of NDM-1-producing Citrobacterfreundii were collected from the First Affiliated Hospital of Kunming Medical University during the period from June 2012 and October 2014.The isolates were identified and subjected to antimicrobial susceptibility testing with VITEK 2 System.Class Ⅰ,Ⅱ,and 1Ⅲ integrons and ISCR1 elements were detected by PCR.Clonal relatedness was assessed by pulsed field gel electrophoresis (PFGE).Results Most (77.8％,14/18) strains were positive for class Ⅰ integron conserved region,27.8％ (5/18) isolates were positive for ISCR1 conserved region.No class Ⅱ or Ⅲ integron was detected.Most (72.2％,13/18) isolates were positive for class Ⅰ integron variable region.None of the strains harbored class Ⅱ integron or ISCR1 variable region.Integron variable regions included gene cassette encoding resistance to aminoglycosides (aadA1,aadA5,aac(6')-Ib-cr) and trimethoprim-sulfamethoxazole (dfrA,dfrA15,dfrA17).PFGE revealed 17 clusters among 18 NDM-l-producing Citrobacter freundii isolates.Conclusions The clonal dissemination of NDM-l-producing Citrobacterfreundii isolates is not significant.Class I integron is prevalent in NDM-l-producing Citrobacter freundii.The presence of ISCR1 is relatively rare.The two mobile elements are not related to the spread of NDM-1 gene in this hospital.
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Objective To investigate the class I integrons and their gene cassettes of imipenem-resistant Pseudomonas aeruginosa (IRPA) , and to analyze the correlation between integrons and drug resistance. Methods PCR was used to determine the presence of integrase genes and class I integrons. The variable regions were detected by sequencing. Resistance genes of integron gene cassettes including metal-β-lactamases, aminoglycoside modifying enzymes (AMEs), 16SrRNA methylating enzyme and the OprD2 genes were detected by PCR. The VITEK-2 automated system was used to determine the antibiotic susceptibility of integron-positive IRPA strains. Results The positive rates of integrase genes and class I integrons were 23.3%(20/86)and 8.14%(7/86) , and five kinds of gene cassettes were detected in 86 IRPA strains. The class I integrons-positive bacterial strains exhibited different resistant patterns to 12 antibiotics with large number of resistance genes. Conclusion The class I integrons and their gene cassettes are associated with multiple drug resistance of IRPA.
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Objective To establish the in vitro biofilm model of Laribacter hongkongensis(LH),to analyze the type Ⅰ integron related genes carried by LH and to investigate the mechanism of LH resistance to quinolones.Methods The biofilm forming abilities of LH clinical isolates were determined by Giemsa staining qualitative method and by crystal violet staining semi-quantitative method.The sensitivity of LH to norfloxacin,ofloxacin,levofloxacin,ciprofloxacin and lomefloxacin in both planktonic and biofilm conditions were dectermined by broth microdilution susceptibility tests.Type I integron related genes carried in 18 LH strains resistant to quinolone were detected by PCR amplification method.Results The detection results by Giemsa staining demonstrated that 36 strains in 55 LH clinical isolates formed visible biofilm,and the biofilm formation rate was 65.4%(36/55).In the biofilm forming ability detected by crystal violet staining semi-quantitative method,OD560≤0.15 was in 8 strains of LH,0.150.20 in 7 strains respectively.The levels of minimal biofilm inhibitory concentration in norfloxacin,ofloxacin,levofloxacin,ciprofloxacin and lomefloxacin to LH were respectively higher than the minimal inhibitory concentration(MIC) in the corresponding floating bacteria(P<0.05).Among 55 strains of LH,18 strains were resistant to quinolones,the resistance rate was 32.7%,and the type I integron in 18 strains of LH carried the drug resistant genes,these drug resistant genes played the drug resistance role in corresponding bacterial strains.Conclusion Drug resistance gene formation and widespread of LH may be associated with type I integron.
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Objective To analyze the species classification and chracteristics of drug resistance and virulence in CTX-M producing Escherichia coli isolated from urine culture.Methods Escherichia coli cultured by urine were collected from our hospital during 2014,the ring disk diffusion test was implemented to determine the bacterial susceptibility,the EBLs determination test was used to analyze the bacterial EBLs producing situation;the enterobactoer duplicated gene spacer consensus sequency PCR(ERIC-PCR) was adopted to perform the genetic relation analysis;PCR was used to amplify the CTX-M encoding genes and multiple virulence genes iutA,ompT,fyuA,fdeC,fimH,traT,cvaC,pap,kpsMT,pAI,usp,aer,hlyA,cnf and chuA;the multiple PCR was used to analyze the species calssification of CTX-M-producing Escherichia coli;these strains of bacteria were classified as the CTX-M-producing group and non-CTX-M-producing group according to the results of CTX-M coding gene detection,the differences in the antibacterial drug resistance and virulence genes between the two gorups were performed the contrastive analysis.Results One hundred and sixty-two strains of E.coli by urine culture had no genetic correlation,among 126 EBLs positive strains,91 strains produced CT-M,in which 57 strains of CT-M producing Escherichia coli belonged to type D,and 116 strains belong to Type B2.The statistical analysis found that the drug resistance rate in the CTX-M-producing group was significantly higher than that in the non-CT-M producing group (except for imipenem),the prevalence of virulence genes including iutA,chuA and traT in the CT-M producing bacteria group was significantly higher than that in the non-CTX-M-producing group(P=0.001,0.006,0.000)Conclusion CTX-M-producing E.coli is main pathogenic bacterium of urinary infection in our hospital,its majority belong to type D with increased drug resistance,moreover has close correlation with virulence genes iutA,chuA and traA and is a pertential threat in clinical treatment of urinary infection.
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Objective To investigate the changes of drug resistance and class Ⅰ integron in clinically isolated Pseudomonas aeruginosa(PA) in our hospital form January 2013 to December 2015.Methods Clinically isolated PA strains were divided into the 3 time periods of 2013,2014 and 2015.Their resistance to 22 commonly used antibacterial drugs was investigated by adopting the VITEK-2;200 strains were randomly selected from the isolated strains during these 3 time periods.Class Ⅰ integron was detect by PCR.Results The detected PA in these 3 time periods had 366,437 and 520 strains respectively.The drug resistance of Pseudomonas aeruginosa to 22 commonly used antibacterial drugs was remarkably increased(P<0.05),especially in ICU.The detection rate of class Ⅰ integron positive bacteria was gradually increased year by year,moreover the drug resistance rate of class Ⅰ integron positive bacteria was significantly higher than that of class Ⅰ integron negative bacteria (P<0.01).Conclusion The drug resistance rate of PA in this hospital is higher.The proportions of multi-drug resistance and classⅠ integron are significantly increased.The hospital infection detection and drug-resistant bacterial monitoring should be strengthened to further standardize the use of antibacterial drugs.
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Objective To investigate antibiotics resistance of Proteus mirabilis isolated from stools of patients with acute diarrhea for the prevention and treatment of its infection and the rational use of antibiotics. Methods Stool samples of acute diarrhea patients were collected in the diarrhea outpatient clinic of the Second Hospital of Tianjin Medical University and Tianjin Medical University General Hospital from 2013 to 2014. Enrichment culture and biochemical identification were used to isolate and identify Proteus mirabilis, which were further performed antimicrobial susceptibility testing and class 1 integron detection. Extended spectrum β-lactamases (ESBLs) phenotype and ESBLs genes (TEM, OXA and CTX-M) were amplified by polymerase chain reaction (PCR), and sequencing were carried on in parts of suspected isolates. ESBLs-positive strains were analyzed by pulsed-field gel electrophoresis (PFGE). Results A total of 277 strains of non-repetitive Proteus mirabilis were isolated, and 268 of them were performed antimicrobial susceptibility testing (the remaining 9 strains failed to recover). Relative higher resistant rates were trimethoprim/sulfamethoxazole (30.2%), ampicillin (25.4%), nalidixic acid (25.7%), streptomycin (21.6%) and chloramphenicol (21.3%). The multiple drug resistance rate was 24.6% (66/268). The positive rate of class 1 integron was 22.8%(61/268). Resistance rates to third-generation cephalosporin, ciprofloxacin and imipenem were less than 10%, but 4 isolates were resistant to imipenem, third-generation cephalosporin, fluoroquinolones, trimethoprim/sulfamethoxazole, and chloramphenicol simultaneously. Three cefotaxime-resistant strains (1062, 1505 and 1650) were positive for ESBLs phenotype and harbored CTX-M extended-spectrum β-lactamase genes, among them 2 strains also carried TEM and/or OXA β-lactamase genes. The clustering analysis of pulsed-field gel electrophoresis (PFGE) displayed that the similarities between 1505 and 1650 were 85.7%, and the similarity with 1062 was 58.1%. Conclusion Proteus mirabilis isolated from patients with acute diarrhea in our city show significant multidrug resistance, high positive rate of class 1 integron, and emergence of ESBLs-positive strains resistant to imipenem and fluoroquinolones, which pose a threat to public health. Rational use of antibiotics is important in both clinical and nonclinical settings.
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Abstract In Latin America, the disease burden of shigellosis is found to coexist with the rapid and rampant spread of resistance to commonly used antibiotics. The molecular basis of antibiotic resistance lies within genetic elements such as plasmids, transposons, integrons, genomic islands, etc., which are found in the bacterial genome. Integrons are known to acquire, exchange, and express genes within gene cassettes and it is hypothesized that they play a significant role in the transmission of multidrug resistance genes in several Gram-negative bacteria including Shigella. A few studies have described antibiotic resistance genes and integrons among multidrug resistant Shigella isolates found in Latin America. For example, in Brazil, Bolivia, Chile, Costa Rica and Peru, class 1 and class 2 integrons have been detected among multidrug resistant strains of Shigella; this phenomenon is more frequently observed in S. flexneri isolates that are resistant to trimethoprim, sulfamethoxazole, streptomycin, ampicillin, chloramphenicol, and tetracycline. The gene cassette sul2, which is frequently detected in Shigella strains resistant to the sulfonamides, suggests that the sulfonamide-resistant phenotype can be explained by the presence of the sul2 genes independent of the integron class detected. It is to be noted that sul3 was negative in all isolates analyzed in these studies.The high frequency of sulfonamide (as encoded by sul2) and trimethoprim resistance is likely to be a result of the recurrent use of trimethoprim sulfamethoxazole as a popular regimen for the treatment of shigellosis. The observed resistance profiles of Shigella strains confirm that ampicillin and trimethoprim-sulfamethoxazole are ineffective as therapeutic options. In-depth information regarding antibiotic resistance mechanism in this pathogen is needed in order to develop suitable intervention strategies. There is a pressing need for regional and local antimicrobial resistance profiling of Shigella to be included as a part of the public health strategy.
Subject(s)
Shigella/drug effects , Shigella/genetics , Drug Resistance, Bacterial , Integrons , Dysentery, Bacillary/microbiology , Dysentery, Bacillary/epidemiology , Anti-Bacterial Agents/pharmacology , Population Surveillance , Dysentery, Bacillary/drug therapy , Genetic Loci , Genes, Bacterial , Latin America/epidemiology , Anti-Bacterial Agents/therapeutic useABSTRACT
Background: Integrons are the main contributors to the development of multidrug resistance (MDR) among Gram‑negative bacilli. There is a lack of knowledge about the molecular relation between gene cassettes and antibiotic resistance in India. Objective: In this study, we have investigated the occurrence of Class II integron and their cassette array among Enterobacteriaceae. Materials and Methods: A total of 268 MDR non‑duplicate strains of Enterobacteriaceae were collected from Silchar Medical College and Hospital, Silchar, Assam, India, during June 2012 to May 2013. Polymerase chain reaction was performed for detection of the integrase genes and gene cassettes within the Class II integron which were further analysed by sequencing. Results: Class II integron was observed in 47 isolates. Four different gene cassette arrangements were detected: dfrA1‑sat2‑aadA1; dfrA1‑sat2‑aadA1‑orfX‑ybeA‑ybfA‑ybfB‑ybgA; dfrA12‑sat2‑aadA1; and dfrA1‑linF‑aadA1. The most prevalent cassette combination was dfrA1‑sat2‑aadA1. This study has also identified a set of gene cassette associated with linF gene instead of sat2 gene. Conclusion: Further investigation is required to determine the current situation and important reservoir of Class II integron for the transmission of drug resistance among Enterobacteriaceae and their contribution to antimicrobial resistance in hospital environment.
ABSTRACT
Abstract Fecal bacteria are considered to be a potential reservoir of antimicrobial resistance genes in the aquatic environment and could horizontally transfer these genes to autochthonous bacteria when carried on transferable and/or mobile genetic elements. Such circulation of resistance genes constitutes a latent public health hazard. The aim of this study was to characterize the variable region of the class 1 integron and relate its genetic content to resistance patterns observed in antimicrobial-resistant Escherichia coli isolated from the surface waters of Patos Lagoon, Southern Brazil. Genetic diversity of the isolates and presence of the qacEΔ1 gene, which confers resistance to quaternary ammonium compounds, were also investigated. A total of 27 isolates were analyzed. The variable region harbored dfrA17, dfrA1 and dfrA12 genes, which confer resistance to trimethoprim, and aadA1, aadA5 and aadA22 genes that encode resistance to streptomycin/spectinomycin. Most of the isolates were considered resistant to quaternary ammonium compounds and all of them carried the qacE Δ1 gene at the 3′ conserved segment of the integron. ERIC-PCR analyses of E. coli isolates that presented the integrons showed great genetic diversity, indicating diverse sources of contamination in this environment. These results suggest that fecal bacteria with class 1 integrons in aquatic environments are potentially important reservoirs of antibiotic-resistance genes and may transfer these elements to other bacteria that are capable of infecting humans.