Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 20 de 139
Electron. j. biotechnol ; 39: 67-73, may. 2019. graf, tab
Article in English | LILACS | ID: biblio-1052039


BACKGROUND: The supplementation of betaine, an osmoprotective compatible solute, in the cultivation media has been widely used to protect bacterial cells. To explore the effects of betaine addition on industrial fermentation, Escherichia coli THRD, an L-threonine producer, was used to examine the production of L-threonine with betaine supplementation and the underlying mechanism through which betaine functions was investigated. RESULTS: Betaine supplementation in the medium of E. coli THRD significantly improved L-threonine fermentation parameters. The transcription of zwf and corresponding enzyme activity of glucose-6-phosphate dehydrogenase were significantly promoted by betaine addition, which contributed to an enhanced expression of zwf that provided more nicotinamide adenine dinucleotide phosphate (NADPH) for L-threonine synthesis. In addition, as a result of the betaine addition, the betaine-stimulated expression of enhanced green fluorescent protein (eGFP) under the zwf promoter within a plasmid-based cassette proved to be a transcription-level response of zwf. Finally, the promoter of the phosphoenolpyruvate carboxylase gene ppc in THRD was replaced with that of zwf, while L-threonine fermentation of the new strain was promoted by betaine addition. Conclusions: We reveal a novel mode of betaine that facilitates the microbial production of useful compounds. Betaine supplementation upregulates the expression of zwf and increases the NADPH synthesis, which may be beneficial for the cell growth and thereby promote the production of L-threonine. This finding might be useful for the production of NADPH-dependent amino acids and derivatives in E. coli THRD or other E. coli strains.

Threonine/metabolism , Betaine/metabolism , Escherichia coli/metabolism , Osmosis , Pentose Phosphate Pathway , Reverse Transcriptase Polymerase Chain Reaction , Escherichia coli/enzymology , Fermentation , Glucosephosphate Dehydrogenase/metabolism , NADP
West Indian med. j ; 67(4): 344-349, Oct.-Dec. 2018. tab
Article in English | LILACS | ID: biblio-1045862


ABSTRACT Objective: To determine the role of extended-spectrum β-lactamases in carbapenem-resistant Gram-negative bacteria from south-western Nigeria. Methods: Twenty-seven carbapenem-resistant isolates that were found to be non-carbapenemase producers (15 Escherichia coli, 9 Klebsiella pneumoniae and 3 Pseudomonas aeruginosa) were further studied. These isolates were subjected to analysis including phenotypic and genotypic detection of various β-lactamases, efflux activity, outer membrane protein, plasmids replicon typing, detection of transferable genes and resistances and typing using random amplified polymorphic DNA tests. Results: No isolates demonstrated de-repression of efflux, but all showed either complete loss or reduced production of outer membrane proteins. Transconjugants from these strains contained various genes including plasmid-mediated quinolone resistance and extended-spectrum beta-lactamases. All the transconjugants carried the blaCTX-M-15 gene. The transconjugants had varying minimum inhibitory concentrations of carbapenems ranging from 0.03 μg/ml to 8 μg/ml. Varying resistances to other antimicrobial agents were also transferred with the plasmids. The donor isolates were not clonally related by molecular typing. Conclusion: Resistance to carbapenem antibiotics in this sample was not mediated only by carbapenemases but also by production of extended-spectrum β-lactamases (largely CTX-M-15), accompanied by protein loss. This was an important mechanism underpinning carbapenem resistance in these clinical isolates of various species.

RESUMEN Objetivo: Determinar el papel de las betalactamasas de espectro extendido en la resistencia al carbapenem en las bacterias gramnegativas en Nigeria. Métodos: Veintisiete aislados resistentes al carbapenem que fueron hallados productores de no carbapenemasas (15 Escherichia coli, 9 Klebsiella pneumoniae, y 3 Pseudomonas aeruginosa) fueron estudiados con mayor profundidad. Estos aislados fueron sometidos a análisis incluyendo la detección fenotípica y genotípica de varias betalactamasas, la actividad de eflujo, las porinas de la membrana externa, la tipificación del replicón plasmídico, la detección de genes transferibles y resistencias y tipificación usando pruebas de ADN polimórficas amplificadas aleatorias. Resultados: Ninguno de los aislamientos mostró desrepresión de eflujo, pero todos demostraron la pérdida completa o la producción reducida de porinas externas de la membrana. Los transconjugantes de estas cepas contenían varios genes incluyendo resistencia a la quinolona mediada por plásmidos y betalactamasas de espectro extendido. Todos los transconjugantes portaban el gen blaCTX-M-15. Los transconjugantes tenían diversas concentraciones inhibitorias mínimas de carbapenemas que oscilaban entre 0.03 μg/ml y 8 μg/ml. Varias resistencias a otros agentes antimicrobianos fueron también transferidas con los plásmidos. Los aislamientos del donante no estuvieron relacionados clonalmente por tipificación molecular. Conclusión: La resistencia al antibiótico carbapenem en esta muestra no fue mediada solamente por las carbapenemasas, sino también por la producción de betalactamasas de espectro extendido (en gran parte CTX-M-15), acompañado por pérdida de porina. Éste era un mecanismo importante que sustentaba la resistencia al carbapenem en estos aislados clínicos de varias especies.

Humans , Pseudomonas aeruginosa/drug effects , beta-Lactamases/biosynthesis , Escherichia coli/drug effects , Klebsiella pneumoniae/drug effects , Anti-Bacterial Agents/pharmacology , Phenotype , Pseudomonas aeruginosa/enzymology , Drug Resistance, Microbial , Microbial Sensitivity Tests , Escherichia coli/enzymology , Genotype , Klebsiella pneumoniae/enzymology , Nigeria
Braz. j. microbiol ; 49(3): 471-480, July-Sept. 2018. tab, graf
Article in English | LILACS | ID: biblio-951821


Abstract Escalating burden of antibiotic resistance that has reached new heights present a grave concern to mankind. As the problem is no longer confined to clinics, we hereby report identification of a pandrug resistant Escherichia coli isolate from heavily polluted Delhi stretch of river Yamuna, India. E. coli MRC11 was found sensitive only to tobramycin against 21 antibiotics tested, with minimum inhibitory concentration values >256 µg/mL for amoxicillin, carbenicillin, aztreonam, ceftazidime and cefotaxime. Addition of certain heavy metals at higher concentrations were ineffective in increasing susceptibility of E. coli MRC11 to antibiotics. Withstanding sub-optimal concentration of cefotaxime (10 µg/mL) and mercuric chloride (2 µg/mL), and also resistance to their combinatorial use, indicates better adaptability in heavily polluted environment through clustering and expression of resistance genes. Interestingly, E. coli MRC11 harbours two different variants of blaTEM (blaTEM-116 and blaTEM-1 with and without extended-spectrum activity, respectively), in addition to mer operon (merB, merP and merT) genes. Studies employing conjugation, confirmed localization of blaTEM-116, merP and merT genes on the conjugative plasmid. Understanding potentialities of such isolates will help in determining risk factors attributing pandrug resistance and strengthening strategic development of new and effective antimicrobial agents.

Metals, Heavy/pharmacology , Drug Resistance, Multiple, Bacterial , Rivers/microbiology , Escherichia coli/drug effects , Anti-Bacterial Agents/pharmacology , Operon , beta-Lactamases/genetics , beta-Lactamases/metabolism , Microbial Sensitivity Tests , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Escherichia coli/isolation & purification , Escherichia coli/enzymology , Escherichia coli/genetics , India
Rev. Soc. Bras. Med. Trop ; 51(1): 88-93, Jan.-Feb. 2018. tab
Article in English | LILACS | ID: biblio-1041448


Abstract INTRODUCTION: Here, we determined the genes encoding antibiotic resistance enzymes and virulence factors and evaluated the genetic relationship between Enterobacter spp. isolated from different clinical samples. METHODS: A total of 57 clinical isolates of Enterobacter spp. were tested for the production of extended-spectrum β-lactamases (ESBLs), carbapenemase, and AmpC using phenotypic and genotypic methods. RESULTS: The most common ESBLs and AmpC β-lactamases were bla TEM (63.3%) and bla EBC (57.7%), respectively. The most prevalent virulence gene was rpos (87.7%). The random amplified polymorphic DNA (RAPD) patterns of strains were genetically unrelated. CONCLUSIONS: RAPD polymerase chain reaction analysis revealed high genetic diversity among isolates.

Humans , Bacterial Proteins/biosynthesis , Bacterial Proteins/genetics , beta-Lactamases/genetics , Escherichia coli/drug effects , Feces/microbiology , Anti-Bacterial Agents/pharmacology , Phenotype , Bacterial Proteins/drug effects , beta-Lactamases/biosynthesis , Polymerase Chain Reaction , Clone Cells , Drug Resistance, Multiple, Bacterial , beta-Lactams/adverse effects , Escherichia coli/enzymology , Escherichia coli/genetics , Disk Diffusion Antimicrobial Tests , Genotype , Iran
Rev. Soc. Bras. Med. Trop ; 51(1): 44-51, Jan.-Feb. 2018. tab, graf
Article in English | LILACS | ID: biblio-897051


Abstract INTRODUCTION: Multidrug-resistant (MDR) Escherichia coli, a species that is a leading cause of urinary tract infections (UTIs) and is a major global public health concern. This study was designed to detect the differences in antibiotic resistance patterns, the production and type of extended spectrum β-lactamases (ESBLs), and the clonal relationships among E. coli isolates from UTIs and fecal samples. METHODS: Antibacterial resistance was determined by the disk diffusion method. ESBL, carbapenemase, and AmpC-producing isolates were detected phenotypically. Then, the ESBL genes were sequenced to detect the type. Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) was performed on the ESBL-positive isolates. RESULTS: The most common effective antibacterial agents were colistin, imipenem, and amikacin. Among the isolates, 204 (56.6%) were MDR. Of the 163 ESBL-positive isolates, 11 (6.7%) produced AmpC, and the frequencies of beta-lactamase-positive genes were as follows: bla CTX-Mgroup1, 76%; bla TEM1, 74.8%; bla SHV12, 1.2%; and bla OXA1, 12.88%. ERIC PCR showed a diverse pattern, suggesting that clonal spread of E. coli in this area is uncommon, and that most of the infecting strains are endogenous. CONCLUSIONS: The high rates of antibacterial-resistant and MDR isolates are quite important since these strains can act as source of resistant bacteria that can be spread in the community. Controlling antibiotic use, against inappropriate use and abuse, in the community and continuous surveillance of emerging resistance traits are critical to controlling the spread of resistance.

Humans , Urinary Tract Infections/microbiology , beta-Lactamases/genetics , Escherichia coli/drug effects , Feces/microbiology , Anti-Bacterial Agents/pharmacology , beta-Lactamases/drug effects , Polymerase Chain Reaction , Drug Resistance, Multiple, Bacterial , Escherichia coli/isolation & purification , Escherichia coli/enzymology , Disk Diffusion Antimicrobial Tests , Iran
Rev. chil. infectol ; 35(1): 29-35, 2018. tab, graf
Article in Spanish | LILACS | ID: biblio-899774


Resumen Introducción Las infecciones del tracto urinario adquiridas en la comunidad (ITUac) causadas por cepas de Escherichia coli productoras de β-lactamasas de espectro extendido (BLEE), principalmente por cepas que contienen el gen blaCTX-M-15, es un fenómeno creciente a nivel mundial. Objetivo Determinar el patrón de susceptibilidad a antimicrobianos de cepas de E. coli productoras de BLEE causantes de ITUac y conocer su patrón molecular. Materiales y Métodos Se realizó un estudio descriptivo en Oaxaca, México, donde se incluyeron 288 cepas de E. coli aisladas de pacientes adultos con posible ITUac. Para obtener los patrones de susceptibilidad antimicrobiana se siguieron los criterios del CLSI y para obtener el análisis molecular se utilizó la técnica de RPC. Resultados Del total de cepas de E. coli aisladas, 31,3% fueron productoras de BLEE, presentando una menor susceptibilidad a antimicrobianos que las cepas no productoras de estas enzimas. El 95,6% de las cepas BLEE estudiadas fueron portadoras del gen blaCTX-M. Conclusiones Un tercio de las ITUac causadas por E. coli en nuestra población fueron causadas por cepas BLEE, mostrando un alto nivel de resistencia a los antimicrobianos comúnmente utilizados en su tratamiento y disminuyendo las opciones terapéuticas para tratamientos empíricos en esta población.

Background Community acquired urinary tract infections (CaUTI) caused by strains of extended-spectrum β-lactamases (ESBL) - producing Escherichia coli, mainly by strains carrying the blaCTX-M-15 gene, is a growing phenomenon worldwide. Aim To determine the antibiotic susceptibility pattern of ESBL-producing E. coli as cause of CaUTI and to identify their molecular pattern. Methods A descriptive study was performed in the city of Oaxaca, Mexico, from where 288 strains of CaUTI-producing strains of E. coli in adults with possible UTI were isolated. The CLSI criteria was followed to determine the antimicrobial susceptibility patterns, and their molecular characterization was performed by using PCR. Results 31.3% of E. coli strains isolated in our population were ESBL producers, which presented higher levels of antibiotic resistance than those of non-producers of these enzymes. 95.6% of the studied strains were carriers of the blaCTX-M gene. Conclusions One-third of the Ca-UTI caused by E. coli in our population are caused by ESBL-producing strains, which present high levels of resistance to the antibiotics widely used in our community. This situation considerably decreases the number of antibiotics available for an empiric treatment against these infections.

Humans , Male , Female , Middle Aged , Urinary Tract Infections/microbiology , beta-Lactamases/drug effects , beta-Lactamases/genetics , Escherichia coli/drug effects , Escherichia coli/genetics , Anti-Bacterial Agents/pharmacology , beta-Lactamases/isolation & purification , Microbial Sensitivity Tests , Community-Acquired Infections/microbiology , beta-Lactam Resistance , Electrophoresis , Escherichia coli/isolation & purification , Escherichia coli/enzymology , Escherichia coli Infections/microbiology , Genotype , Mexico
Rev. chil. obstet. ginecol. (En línea) ; 82(6): 621-625, Dec. 2017.
Article in Spanish | LILACS | ID: biblio-899953


Se comunica el caso de un recién nacido producto de un parto prematuro con rotura prematura de membranas, que desarrolló precozmente meningitis neonatal por Escherichia coli productora de beta-lactamasa de espectro extendido. Los cultivos en líquido céfalo raquídeo y sangre neonatal fueron tempranamente positivos para esta bacteria. No obstante no aislarse este microorganismo en la madre, los hallazgos de la biopsia placentaria y la precocidad de la infección neonatal son determinantes en señalar que se trató de infección intraamniótica con transmisión vertical al neonato. La meningitis neonatal fue tratada con meropenem y el niño se dio de alta en buenas condiciones después de 41 días de hospitalización. Las guías perinatales actuales, preconizan el tamizaje de muestras vaginales para la prevención del parto prematuro y de los resultados adversos asociados a infección bacteriana ascendente durante el embarazo.

We report the case of a newborn resultant of premature delivery with premature rupture of membranes, which developed early-onset neonatal meningitis caused by transmission of Escherichia coli producer of betalactamasa of spectrum extended. Cultures in cerebrospinal fluid and neonatal blood were early positive for this bacterium. Although this microorganism is not isolated in the mother, the findings of the placenta biopsy and the precocity of the neonatal infection are determinant in indicating that it was an intraamniotic infection with vertical transmission to the neonate. Neonatal meningitis was treated with meropenem and the child was discharged in good condition after 41 days of hospitalization. The current perinatal guidelines support the screening of vaginal samples for the prevention of preterm birth and the adverse outcomes associated with ascending bacterial infection during pregnancy.

Humans , Female , Pregnancy , Adult , Fetal Membranes, Premature Rupture , Infectious Disease Transmission, Vertical , Meningitis, Escherichia coli/diagnosis , Meningitis, Escherichia coli/transmission , Obstetric Labor, Premature , beta-Lactamases/biosynthesis , Escherichia coli/enzymology , Escherichia coli Infections/diagnosis , Escherichia coli Infections/transmission
Electron. j. biotechnol ; 30: 64-70, nov. 2017. ilus, graf, tab
Article in English | LILACS | ID: biblio-1021461


Background: The development of a potential single culture that can co-produce hydrogen and ethanol is beneficial for industrial application. Strain improvement via molecular approach was proposed on hydrogen and ethanol co-producing bacterium, Escherichia coli SS1. Thus, the effect of additional copy of native hydrogenase gene hybC on hydrogen and ethanol co-production by E. coli SS1 was investigated. Results: Both E. coli SS1 and the recombinant hybC were subjected to fermentation using 10 g/L of glycerol at initial pH 7.5. Recombinant hybC had about 2-fold higher cell growth, 5.2-fold higher glycerol consumption rate and 3-fold higher ethanol productivity in comparison to wild-type SS1. Nevertheless, wild-type SS1 reported hydrogen yield of 0.57 mol/mol glycerol and ethanol yield of 0.88 mol/mol glycerol, which were 4- and 1.4-fold higher in comparison to recombinant hybC. Glucose fermentation was also conducted for comparison study. The performance of wild-type SS1 and recombinant hybC showed relatively similar results during glucose fermentation. Additional copy of hybC gene could manipulate the glycerol metabolic pathway of E. coli SS1 under slightly alkaline condition. Conclusions: HybC could improve glycerol consumption rate and ethanol productivity of E. coli despite lower hydrogen and ethanol yields. Higher glycerol consumption rate of recombinant hybC could be an advantage for bioconversion of glycerol into biofuels. This study could serve as a useful guidance for dissecting the role of hydrogenase in glycerol metabolism and future development of effective strain for biofuels production.

Ethanol/metabolism , Escherichia coli/metabolism , Hydrogen/metabolism , Hydrogenase/metabolism , Recombination, Genetic , Biodegradation, Environmental , Culture Media , Escherichia coli/enzymology , Alkalinization , Fermentation , Glucose/metabolism , Glycerol/metabolism , Hydrogenase/genetics
Electron. j. biotechnol ; 29: 63-67, sept. 2017. ilus, tab, graf
Article in English | LILACS | ID: biblio-1017249


Background: Pullulanase production in both wild-type strains and recombinantly engineered strains remains low. The Shine-Dalgarno (SD) sequence and stem-loop structure in the 5' or 3' untranslated region (UTR) are well-known determinants of mRNA stability. This study investigated the effect of mRNA stability on pullulanase heterologous expression. Results: We constructed four DNA fragments, pulA, SD-pulA, pulA-3t, and SD-pulA-3t, which were cloned into the expression vector pHT43 to generate four pullulanase expression plasmids. The DNA fragment pulA was the coding sequence (CDS) of pulA in Klebsiella variicola Z-13. SD-pulA was constructed by the addition of the 5' SD sequence at the 5' UTR of pulA. pulA-3t was constructed by the addition of a 3' stem-loop structure at the 3' UTR of pulA. SD-pulA-3t was constructed by the addition of the 5' SD sequence at the 5' UTR and a 3' stem-loop structure at the 3' UTR of pulA. The four vectors were transformed into Escherichia coli BL21(DE3). The pulA mRNA transcription of the transformant harboring pHT43-SD-pulA-3t was 338.6%, 34.9%, and 79.9% higher than that of the other three transformants, whereas the fermentation enzyme activities in culture broth and intracellularly were 107.0 and 584.1 times, 1.2 and 2.0 times, and 62.0 and 531.5 times the amount of the other three transformants (pulA, SD-pulA, and pulA-3 t), respectively. Conclusion: The addition of the 5' SD sequence at the 5' UTR and a 3' stem-loop structure at the 3' UTR of the pulA gene is an effective approach to increase pulA gene expression and fermentation enzyme activity.

Escherichia coli/enzymology , Escherichia coli/genetics , Glycoside Hydrolases/metabolism , Transformation, Genetic , Gene Expression , Reverse Transcriptase Polymerase Chain Reaction , RNA Stability , Fermentation , Genetic Vectors , Glycoside Hydrolases/genetics
Electron. j. biotechnol ; 26: 27-32, Mar. 2017. tab, ilus, graf
Article in English | LILACS | ID: biblio-1009654


Background: An effective single culture with high glycerol consumption and hydrogen and ethanol coproduction yield is still in demand. A locally isolated glycerol-consuming Escherichia coli SS1 was found to produce lower hydrogen levels under optimized ethanol production conditions. Molecular approach was proposed to improve the hydrogen yield of E. coli SS1 while maintaining the ethanol yield, particularly in acidic conditions. Therefore, the effect of an additional copy of the native hydrogenase gene hycE and recombinant clostridial hydrogenase gene hydA on hydrogen production by E. coli SS1 at low pH was investigated. Results: Recombinant E. coli with an additional copy of hycE or clostridial hydA was used for fermentation using 10 g/L (108.7 mmol/L) of glycerol with an initial pH of 5.8. The recombinant E. coli with hycE and recombinant E. coli with hydA showed 41% and 20% higher hydrogen yield than wild-type SS1 (0.46 ± 0.01 mol/mol glycerol), respectively. The ethanol yield of recombinant E. coli with hycE (0.50 ± 0.02 mol/mol glycerol) was approximately 30% lower than that of wild-type SS1, whereas the ethanol yield of recombinant E. coli with hydA (0.68 ± 0.09 mol/mol glycerol) was comparable to that of wild-type SS1. Conclusions: Insertion of either hycE or hydA can improve the hydrogen yield with an initial pH of 5.8. The recombinant E. coli with hydA could retain ethanol yield despite high hydrogen production, suggesting that clostridial hydA has an advantage over the hycE gene in hydrogen and ethanol coproduction under acidic conditions. This study could serve as a useful guidance for the future development of an effective strain coproducing hydrogen and ethanol.

Ethanol/metabolism , Escherichia coli/metabolism , Hydrogen/metabolism , Biotechnology , Recombinant Proteins , Clostridium/genetics , Clostridium/metabolism , Escherichia coli/enzymology , Escherichia coli/genetics , Fermentation , Glycerol , Hydrogen-Ion Concentration , Hydrogenase/genetics , Hydrogenase/metabolism
Electron. j. biotechnol ; 19(6): 79-83, Nov. 2016. ilus
Article in English | LILACS | ID: biblio-840317


Background: Cold-active endo-1, 4-β-glucanase (EglC) can decrease energy costs and prevent product denaturation in biotechnological processes. However, the nature EglC from C. farmeri A1 showed very low activity (800 U/L). In an attempt to increase its expression level, C. farmeri EglC was expressed in Escherichia coli as an N-terminal fusion to protein S (ProS) from Myxococcus xanthus. Results: A novel expression vector, pET(ProS-EglC), was successfully constructed for the expression of C. farmeri EglC in E. coli. SDS-PAGE showed that the recombinant protein (ProS-EglC) was approximately 60 kDa. The activity of ProS-EglC was 12,400 U/L, which was considerably higher than that of the nature EglC (800 U/L). ProS-EglC was active at pH 6.5-pH 8.0, with optimum activity at pH 7.0. The recombinant protein was stable at pH 3.5-pH 6.5 for 30 min. The optimal temperature for activity of ProS-EglC was 30°C-40°C. It showed greater than 50% of maximum activity even at 5°C, indicating that the ProS-EglC is a cold-active enzyme. Its activity was increased by Co2+ and Fe2+, but decreased by Cd2+, Zn2+, Li+, methanol, Triton-X-100, acetonitrile, Tween 80, and SDS. Conclusions: The ProS-EglC is promising in application of various biotechnological processes because of its cold-active characterizations. This study also suggests a useful strategy for the expression of foreign proteins in E. coli using a ProS tag.

Cellulases/metabolism , Citrobacter/enzymology , Escherichia coli/enzymology , Myxococcus xanthus/enzymology , Cold Temperature , Genetic Vectors , Recombinant Proteins
Braz. j. microbiol ; 47(3): 706-711, July-Sept. 2016. tab, graf
Article in English | LILACS | ID: lil-788959


Abstract This study was conducted in Iran in order to assess the distribution of CTX-M type ESBLs producing Enterobacteriaceae. From January 2012 to December 2013, totally 198 E. coli, 139 Klebsiella spp, 54 Salmonella spp and 52 Shigella spp from seven hospitals of six provinces in Iran were screened for resistance to extended-spectrum cephalosporins. After identification and susceptibility testing, isolates presenting multiple-drug resistance (MDR) were evaluated for ESBL production by the disk combination method and by Etest using (cefotaxime and cefotaxime plus clavulanic acid). All isolates were also screened for bla CTX-M using conventional PCR. A total of 42.92%, 33.81%, 14.81% and 7.69% of the E. coli, Klebsiella spp, Salmonella spp and Shigella spp isolates were MDR, respectively. The presence of CTX-M enzyme among ESBL-producing isolates was 85.18%, 77.7%, 50%, and 66.7%, in E. coli, Klebsiella spp, Salmonella spp and Shigella spp respectively. The overall presence of CTX-M genes in Enterobacteriaceae was 15.4% and among the resistant isolates was 47.6%. This study indicated that resistance to β-lactams mediated by CTX-M enzymes in Iran had similar pattern as in other parts of the world. In order to control the spread of resistance, comprehensive studies and programs are needed.

Humans , Salmonella/enzymology , Shigella/enzymology , beta-Lactamases/metabolism , Cross Infection , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae Infections/epidemiology , Escherichia coli/enzymology , Klebsiella/enzymology , Salmonella/drug effects , Shigella/drug effects , beta-Lactamases/genetics , Microbial Sensitivity Tests , Cross-Sectional Studies , Escherichia coli/drug effects , Iran/epidemiology , Klebsiella/drug effects , Anti-Bacterial Agents/pharmacology
Mem. Inst. Oswaldo Cruz ; 111(5): 349-354, May 2016. graf
Article in English | LILACS | ID: lil-782047


During its life cycle Leishmania spp. face several stress conditions that can cause DNA damages. Base Excision Repair plays an important role in DNA maintenance and it is one of the most conserved mechanisms in all living organisms. DNA repair in trypanosomatids has been reported only for Old World Leishmania species. Here the AP endonuclease from Leishmania (L.) amazonensis was cloned, expressed in Escherichia coli mutants defective on the DNA repair machinery, that were submitted to different stress conditions, showing ability to survive in comparison to the triple null mutant parental strain BW535. Phylogenetic and multiple sequence analyses also confirmed that LAMAP belongs to the AP endonuclease class of proteins.

DNA Damage/genetics , DNA Repair/genetics , DNA-(Apurinic or Apyrimidinic Site) Lyase/genetics , Escherichia coli/genetics , Leishmania braziliensis/genetics , Mutation/genetics , Amino Acid Sequence , Escherichia coli Proteins/genetics , Escherichia coli/enzymology , Molecular Sequence Data
Braz. j. microbiol ; 47(1): 150-158, Jan.-Mar. 2016. tab, graf
Article in English | LILACS | ID: lil-775101


Abstract Antimicrobial resistance in Escherichia coli isolated from pet dogs can be considered a potential threat of infection for the human population. Our objective was to characterize the resistance pattern, extended spectrum beta-lactamase production and genetic relatedness of multiresistant E. coli strains isolated from dogs (n = 134), their owners (n = 134), and humans who claim to have no contact with dogs (n = 44, control), searching for sharing of strains. The strains were assessed for their genetic relatedness by phylogenetic grouping and pulsed-field gel electrophoresis. Multiresistant E. coli strains were isolated from 42 (31.3%) fecal samples from pairs of dogs and owners, totaling 84 isolates, and from 19 (43.1%) control group subjects. The strains showed high levels of resistance to ampicillin, streptomycin, tetracycline, trimethoprim and sulfamethoxazole regardless of host species or group of origin. The blaTEM, blaCTX-M, and blaSHV genes were detected in similar proportions in all groups. All isolates positive for bla genes were ESBL producers. The phylogenetic group A was the most prevalent, irrespective of the host species. None of the strains belonging to the B2 group contained bla genes. Similar resistance patterns were found for strains from dogs, owners and controls; furthermore, identical PFGE profiles were detected in four (9.5%) isolate pairs from dogs and owners, denoting the sharing of strains. Pet dogs were shown to be a potential household source of multiresistant E. coli strains.

Animals , Dogs , Humans , Drug Resistance, Bacterial , Escherichia coli Infections/microbiology , Escherichia coli Infections/veterinary , Escherichia coli/drug effects , Escherichia coli/enzymology , Genotype , beta-Lactamases/genetics , Anti-Bacterial Agents/pharmacology , Electrophoresis, Gel, Pulsed-Field , Escherichia coli/genetics , Feces/microbiology , Molecular Typing , Pets , Phylogeny
Salud pública Méx ; 57(5): 412-418, sep.-oct. 2015. ilus, tab
Article in English | LILACS | ID: lil-764722


Objective. To assess the risks factors for urinary tract infections (UTIs) caused by Extended-Spectrum Beta-Lactamases (ESBLs)-producing E. coli and the molecular characterization of ESBLs. Materials and methods. A case-control study was performed to identify risk factors in consecutively recruited patients with UTIs caused by ESBLs or non-ESBLs-producing E. coli in a tertiary hospital in Mexico. Results. ESBLs-producing E. coli were isolated from 22/70 (31%) patients with E. coli UTIs over a three month period. All isolates were resistant to cephalosporins and quinolones but susceptible to carbapenems, amikacin and nitrofurantoin. Prior antibiotic treatment with more than two antibiotic families (OR=6.86; 95%CI 1.06-157.70; p=0.028), recurrent symptomatic UTIs (OR=5.60; 95%CI 1.88-17.87; p=0.001) and previous hospitalization (OR=5.06; 95%CI 1.64-17.69; p=0.002) were significant risk factors. Sixteen isolates harbored the beta-lactamase (bla)CTX-M-15 gene and five the blaTEM-1 gene. Conclusions. One of every three patients presented UTIs with ESBLs-producing beta-lactams and fluoroquinolone resistant E. coli. Risk factors and resistance patterns must be taken into account for developing antibiotic use policies in these settings.

Objetivo. Evaluar los factores de riesgo en infecciones de vías urinarias (IVUs) causadas por E. coli productora de Beta-Lactamasas de espectro extendido (BLEEs) y caracterizar las BLEEs. Material y métodos. Estudio de casos y controles en pacientes consecutivos con IVUs causadas por E. coli productoras o no de BLEEs en un hospital de referencia. Resultados. E. coli productora de BLEEs se aisló en 22/70 (31%) pacientes con IVUs por E. coli durante un periodo de tres meses. Todos los aislamientos fueron resistentes a cefalosporinas y quinolonas, pero susceptibles a carbapenemes, amikacina y nitrofurantoina. Factores de riesgo significativos incluyeron tratamiento previo con más de dos familias de antibióticos (OR=6.86; IC95% 1.06-157.70; p=0.028), IVUs sintomáticas recurrentes (OR=5.60; IC95% 1.88-17.87; p=0.001) y hospitalizaciones previas (OR=5.06; IC95% 1.64-17.69; p=0.002). Dieciséis aislamientos presentaron el gen betalactamasas (bla)CTX-M-15 y cinco el gen blaTEM-1. Conclusiones. Uno de cada tres pacientes presentó IVU con E. coli resistente a beta-lactámicos, fluoroquinolonas y productora de BLEEs. En estos casos, los factores de riesgo y patrones de resistencia deberían tomarse en cuenta para recomendar tratamiento.

Humans , Male , Female , Adult , Middle Aged , Aged , Aged, 80 and over , Bacterial Proteins/genetics , Urinary Tract Infections/microbiology , beta-Lactamases/genetics , Escherichia coli/enzymology , Escherichia coli Infections/microbiology , Tertiary Care Centers , Urinary Tract Infections/epidemiology , Case-Control Studies , Cross Infection/microbiology , Cross Infection/epidemiology , Community-Acquired Infections/microbiology , Community-Acquired Infections/epidemiology , beta-Lactam Resistance , Drug Resistance, Multiple, Bacterial , Drug Utilization , Hospitalization , Anti-Bacterial Agents/therapeutic use
Braz. j. microbiol ; 46(3): 649-657, July-Sept. 2015. tab, ilus
Article in English | LILACS | ID: lil-755803


To facilitate the biodegradation of diesel oil, an oil biodegradation bacterial consortium was constructed. The alkane hydroxylase (alkB) gene of Pseudomonas putida GPo1 was constructed in a pCom8 expression vector, and the pCom8-GPo1 alkB plasmid was transformed into Escherichia coli DH5α. The AlkB protein was expressed by diesel oil induction and detected through SDS-polyacrylamide gel electrophoresis. The culture of the recombinant (pCom8-GPo1 alkB/E. coli DH5α) with the oil biodegradation bacterial consortium increased the degradation ratio of diesel oil at 24 h from 31% to 50%, and the facilitation rates were increased as the proportion of pCom8-GPo1 alkB/E. coli DH5α to the consortium increased. The results suggested that the expression of the GPo1 gene in E. coli DH5α could enhance the function of diesel oil degradation by the bacterial consortium.


Acinetobacter/metabolism , Biodegradation, Environmental , /genetics , Escherichia coli/metabolism , Microbial Consortia/genetics , Organisms, Genetically Modified/metabolism , Pseudomonas putida/enzymology , Acinetobacter/genetics , Escherichia coli/enzymology , Escherichia coli/genetics , Fuel Oils , Gasoline , Genetic Engineering , Oxidation-Reduction , Organisms, Genetically Modified/genetics , Plasmids/genetics , Pseudomonas putida/genetics , Pseudomonas putida/metabolism
Arch. endocrinol. metab. (Online) ; 59(3): 245-251, 06/2015. tab, graf
Article in English | LILACS | ID: lil-751309


Objective Evaluate the effect of glycemic index (GI) on biochemical parameters, food intake, energy metabolism, anthropometric measures and body composition in overweight subjects.Materials and methods Simple blind study, in which nineteen subjects were randomly assigned to consume in the laboratory two daily low GI (n = 10) or high GI (n = 9) meals, for forty-five consecutive days. Habitual food intake was assessed at baseline. Food intake, anthropometric measures and body composition were assessed at each 15 days. Energy metabolism and biochemical parameters were evaluated at baseline and the end of the study.Results Low GI meals increased fat oxidation, and reduced waist circumference and HOMA-IR, while high GI meals increased daily dietary fiber and energy intake compared to baseline. There was a higher reduction on waist circumference and body fat, and a higher increase on postprandial fat oxidation in response to the LGI meals than after high GI meals. High GI meals increased fasting respiratory coefficient compared to baseline and low GI meals.Conclusion The results of the present study showed that the consumption of two daily low GI meals for forty-five consecutive days has a positive effect on obesity control, whereas, the consumption of high GI meals result has the opposite effect. Arch Endocrinol Metab. 2015;59(3):245-51.

Bacterial Proteins/chemistry , Escherichia coli/enzymology , Membrane Proteins/chemistry , Phenylalanine/chemistry , Amino Acid Motifs , Amino Acid Sequence , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Chemotaxis , Conserved Sequence , Dimerization , Escherichia coli/chemistry , Escherichia coli/genetics , Escherichia coli/physiology , Molecular Sequence Data , Membrane Proteins/genetics , Membrane Proteins/metabolism , Protein Conformation , Phenylalanine/genetics , Phenylalanine/metabolism