ABSTRACT
Introducción. La resistencia a los antimicrobianos y la tolerancia a biocidas está dada por mecanismos comunes, generados por su uso en diferentes ambientes; mecanismos como la expresión de bombas de expulsión presentes en bacterias del género Enterobacter circulantes amenaza la eficacia de los antimicrobianos limitando las opciones de terapia antibiótica. Objetivos: Determinar el perfil de tolerancia al triclosán y detección de genes asociados a bombas de expulsión en aislados clínicos de Enterobacter aerogenes y Enterobacter cloacae. Materiales y Métodos: Se realizó un estudio observacional, descriptivo y de corte transversal, se determinaron perfiles de tolerancia al triclosán por microdilución, de susceptibilidad antimicrobiana, confirmación fenotípica de mecanismos de resistencia, por reacción en cadena de la polimerasa, se identificó la presencia de genes que codifican para bombas de expulsión. Resultados: El 17% correspondió a Enterobacter cloacae y el 6% Enterobacter aerogenes. El 93,7% de los aislados clínicos del género Enterobacter presentó el fenotipo de resistencia BLEE y AmpC. En el 81,3% de los aislamientos se obtuvo la presencia de al menos un gen relacionado con las expresión de bombas de expulsión, siendo frecuentes MexC y AcrB; no identificó presencia del gen oqxA. Conclusiones: La resistencia a diferentes grupos de antibióticos se identifica en especies de Enterobacter circulante, así la presencia de enzimas BLEE y AmpC, la presencia de genes relacionados con bombas de expulsión y la alta tolerancia al triclosán. Palabras clave: Triclosán, Resistencia, Bombas de expulsión, Genes, Biocida
Introduction. Antimicrobial resistance and tolerance to biocides is given by common mechanisms, generated by the use of antimicrobial and biocidal substances in different environments, these me- chanisms such as the expression of expulsion pumps present in bacteria of the Enterobacter genus circulating threatens the efficacy of antimicrobials by limiting antibiotic therapy options. Objective: to determine the triclosan tolerance profile and detection of genes associated with expul- sion pumps in clinical isolates of Enterobacter aerogenes and Enterobacter cloacae. Materials and Methods: An observational, descriptive and the cross-sectional study was performed, triclosan tolerance profiles were determined by microdilution, antimicrobial susceptibility, phenotypic confirmation of resistance mechanisms, by the presence of polymerase chain reaction, the presence of genes that code for expulsion pumps. Results: The 17% corresponded to Enterobacter cloacae and 6% Enterobacter aerogenes. 93.7% of the clinical isolates of the genus Enterobacter presented the ESBL and AmpC resistance phenotype. In 81.3% of the isolates, the presence of at least one gene related to the expression of ejection pumps was obtained, with MexC and AcrB being frequent; did not identify the presence of the oqxA gene. conclusions: The resistance to different groups of antibiotics is identified in circulating Enterobacter species, as well as the presence of ESBL and AmpC enzymes, the presence of genes related to ejection pumps, and high tolerance to triclosan.
Introdução.A resistência antimicrobiana e a tolerância a biocidas esta dada pelos mecanismos comuns gerados pelo uso em diferentes ambientes; mecanismos como a expressão de bombas de expulsão presentes em bactérias do gênero Enterobacter circulantes ameaza a eficácia das antimicrobiana limitando as opções de terapia antibiótica. Objetivos: Determinar o perfil de tolerância ao triclosan e detecção dos genes asociados a bombas de expulsão em isolados clínicos Enterobacter aerogenes e Enterobacter cloacae. Materiais e Métodos: Realizou-se um estudo observacional, descritivo e de corte transversal, deter- minaram-se perfiles de tolerância ao triclosan por microdiluição, de susceptibilidade antimicrobiana, confirmação de mecanismos de resistência fenotípica por reação em cadeia da polimerase, identifi- cou-se a presença de genes que codificam para bombas de expulsão. Resultados: 17% correspondeu ao Enterobacter cloacae e 6% ao Enterobacter aerogenes. 93,7% em isolados clínicos do gênero Enterobacter presentou o fenótipo de resistência BLEE e AmpC. No 81% dos isolamentos se obteve a presença de pelo menos um gen relacionado à expressão de bombas de expulsão, sindo frequentes mexC e acrB; não se identificou a presença do gen oqxA. Conclusões: A resistência de diferentes grupos de antibióticos se identificou em espécies de Entero- bacter circulante, assim a presença de enzimas BLEE e AmpC, a presença de genes relacionados com bombas de expulsão e a alta tolerância ao triclosan.
Subject(s)
Drug Resistance, Bacterial , Triclosan , Disinfectants , GenesABSTRACT
BACKGROUND: The aim of the present study was to determine the frequency of six efflux pump genes in Acinetobacter clinical isolates collected from South Korean hospitals. METHODS: In this study, we used a total of 339 Acinetobacter strains, comprising 279 Acinetobacter calcoaceticus–Acinetobacter baumannii (ACB) complex and 60 non-ACB complex strains. We performed specific PCR assays to detect adeG, adeB, adeE, adeY, abeM, and adeJ, transporter genes of the multidrug efflux pumps AdeFGH, AdeABC, AdeDE, AdeXYZ, AbeM, and AdeIJK, respectively. RESULTS: Frequencies of six efflux pump genes varied according to the species of Acinetobacter. Frequencies of adeE, abeM, and adeJ between A. baumannii group and A. nosocomialis group were found to be significantly different. Significant differences were found in the frequencies of adeB, adeE, adeY, and adeJ among the susceptible A. baumannii (SAB), multidrug-resistant A. baumannii (MDRAB), and extensively drug-resistant A. baumannii (XDRAB) groups within the 154 strains of A. baumannii. The frequencies of efflux pump genes in imipenem-susceptible and imipenem-nonsusceptible groups were significantly different for adeB, adeY, and adeJ. The frequencies of efflux pump genes in ciprofloxacin-susceptible and ciprofloxacin-nonsusceptible groups were significantly different for adeB and adeY. No significant difference was found in the frequency of efflux pump genes among groups sampled from different regions of Korea, across 86 strains of A. baumannii collected in 2012. CONCLUSIONS: The frequencies of six efflux pump genes obtained in this study demonstrate the fundamental epidemiological feature of efflux pump genes in Korean Acinetobacter clinical isolates.
Subject(s)
Acinetobacter , Gene Frequency , Genes, MDR , Korea , Polymerase Chain ReactionABSTRACT
BACKGROUND: Acinetobacter baumannii is one of the most important pathogens capable of colonization in burn patients, leading to drug-resistant wound infections. This study evaluated the distribution of the AdeABC efflux system genes and their relationship to ciprofloxacin resistance in A. baumannii isolates collected from burn patients. METHODS: A total of 68 A. baumannii clinical strains were isolated from patients hospitalized in Motahari Burns Center in Tehran, Iran. Ciprofloxacin susceptibility was tested by the disk diffusion and agar dilution methods. PCR amplification of the adeRS-adeB drug efflux genes was performed for all resistant and susceptible isolates. To assess the role of the drug efflux pump in ciprofloxacin susceptibility, carbonyl cyanide 3-chlorophenylhydrazone (CCCP) was used as an efflux pump inhibitor (EPI). RESULTS: Approximately 95.6% of the Acinetobacter isolates were resistant to ciprofloxacin, with minimum inhibitory concentration (MIC) values ranging from 4 to > or =128 microg/mL. The susceptibility of 86.1% of the resistant isolates increased by factors of 2 to 64 in the presence of CCCP. All resistant isolates were positive for the adeRS-adeB genes, and 73.2% of them had mutations in the AdeRS regulatory system. CONCLUSIONS: The results showed that AdeABC genes are common in A. baumannii, which might be associated with ciprofloxacin non-susceptibility, as indicated by the observed linkage to the presence of the genes essential for the activity of the AdeABC, several single mutations occurring in the adeRS regulatory system, and an increase of ciprofloxacin susceptibility in the presence of a CCCP EPI.
Subject(s)
Humans , ATP-Binding Cassette Transporters/antagonists & inhibitors , Acinetobacter Infections/diagnosis , Acinetobacter baumannii/drug effects , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Base Sequence , Ciprofloxacin/pharmacology , DNA, Bacterial/chemistry , Drug Resistance, Bacterial , Hydrazones/pharmacology , Microbial Sensitivity Tests , Mutation , Polymerase Chain ReactionABSTRACT
The efflux pump system has been suggested as an important mechanism in the drug resistance of Mycobacterium tuberculosis (MTB). In this study, molecular analysis of five genes in the efflux pump system of MTB isolates from Korean patients was performed in order to identify appropriate molecular targets. In this study, 35 culture-positive specimens were included. PCR was performed for five efflux genes, mmpL7, efpA, mmr, p55 and tap-like gene. In the 35 clinical isolates, molecular analysis of five kinds of efflux pump genes was performed. Only one clinical isolate showed negative PCR results for all five efflux pump genes. All the rest 34 isolates presented concurrent positive results for the five efflux pump genes. In the near future, gene expression study with quantitative PCR should be performed using these genes.
Subject(s)
Humans , Drug Resistance , Gene Expression , Genes, MDR , Mycobacterium tuberculosis , Polymerase Chain ReactionABSTRACT
Objective To detect the changes on the expression of putative drug effiux genes caused by isoniazid-inducement in single resistance to the isoniazid Mycobacterium tuberculosis (M.tuberculosis) clinical isolates,for exploring the putative effiux genes which causing M.tuberculosis isoniazid resistance as well as the mechanism related to high expression of the putative effiux genes.Methods We selected 35 M.tuberculosis clinical isolates which were only resistant to isoniazid as well as 10 sensitive M.tuberculosis clinical isolates and using H37Rv as control.Each strain was cultured in 7H9 liquid medium without isoniazid and with subinhibitory isoniazid concentration (1/4 MIC) induction.After RNA extraction and reverse transcription,real-time PCR was conducted to assess the expression changes of 27 putative drug effiux pump genes with formula 2-△△CT to calculate the expression of each putative drug efflux pump genes.Results Of the 27 putative genes,13 of them were expressed at high level.High expression of Rv1258c gene had the maximum number of 6strains,followed by high expression of Rv0849 and Rv2265 which both had 5 strains.Fourteen strains (40.00％) out of the 35 strains had high expression pump genes.Six strains (17.14％) had only one highly expressed putative efflux pump gene.Eight strains (22.86％) had two or more highly expressed putative effiux pump genes,including two,four,five,seven genes that highly expressed in 4,2,1,1strains respectively.For the 27 putative genes,ten sensitive strains and H37Rv did not show highly expressed genes.Conclusion Rv1258c,Rv2265,Rv0849,etc.genes might be the putative effiux pumps genes of M.tuberculosis resistant to isoniazid.Isoniazid might serve as the inducer of M.tuberculosis part putative effiux pump genes,inducing activation and causing high expression of these putative effiux pump genes.
ABSTRACT
Objective To investigate the prevalence of multidrug resistant genes in Klebsiella pncumoniae.MethodsTwenty strains of multidrug resistant Klebsiella pneumoniae were isolated from burn patients.Susceptibility of these strains to 14 antibiotics was detected by KB method.PCR was used to detect oqxA,smrKpn,qacE,tehA,mdfA and qacEΔl-sul1 genes.ResultsThe antibiotic sensitivity rates of 20 multidrug resistant Klebsiella pneumoniae isolates to antibiotics tested were ＜ 30％ except that to imipenam.The positive rates of efflux pump genes mdfA,qacEΔl-sull and oqxA were 65％,100％ and 100％,respectively; while those ofsmrKpn,qacE and tehA were 0％,0％ and 15％.ConclusionoqxA gene has been detected in multidrug resistant Klebsiella pneumoniae from burn patients with high positive rate.