RESUMO
Enterococci are intrinsically resistant to several antimicrobial classes and show a great ability to acquire new mechanisms of resistance. Resistance to β-lactam antibiotics is a major concern because these drugs either alone or in combination are commonly used for the treatment of enterococcal infections. Ampicillin resistance, which is rare in Enterococcus faecium occurs in most of the hospital-associated Enterococcus faecium isolates. High-level resistance to ampicillin in E. faecium is mainly due to the enhanced production of PBP5 and/or by polymorphisms in the beta subunit of this protein. The dissemination of high-level ampicillin resistance can be the result of both clonal spread of strains with mutated pbp5 genes and resistance horizontal gene transfer.
Los enterococos son intrínsecamente resistentes a varias clases de antimicrobianos y presentan una gran capacidad para adquirir mecanismos de resistencia. La resistencia a los antibióticos p-lactámicos es preocupante porque estos fármacos solos o combinados se usan comúnmente para el tratamiento de las infecciones enterocócicas. La mayoría de los aislamientos hospitalarios de Enterococcus faecium presentan resistencia a la ampicilina, la cual es rara en Enterococcus faecalis. El alto nivel de resistencia a la ampicilina en E. faecium se debe principalmente a la hiperproducción de PBP5 y/o a polimorfismos en la subunidad beta de esta proteína. La propagación de esta resistencia puede deberse tanto a la diseminación clonal de cepas con genes pbp5 mutados como a la transferencia horizontal de genes.
Assuntos
Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/genética , Farmacorresistência Bacteriana/genética , Ampicilina/antagonistas & inibidores , Resistência a Ampicilina/genéticaRESUMO
Biotechnology industries that use recombinant DNA technology are potential sources for release of genetically modified organisms to the environment. Antibiotic-resistance marker genes are commonly used for recombinant bacteria selection. One example is the marker gene coding for ß-lactamase (bla) in plasmids found in Escherichia coli K-12. The aim of this study was to provide an approach to develop a molecular method for genetic marker detection in E. coli K-12 harboring bla genes from an industrial wastewater treatment effluent pond (IWTEP). For the detection of bla and Achromobacter lyticus protease I (api) genes in samples from IWTEP, we employed multiplex polymerase chain reaction (PCR) using E. coli K-12 genetic marker detection primers, previously described in the literature, and primers designed in our laboratory. The microbiological screening method resulted in 22 bacterial colony-forming units isolated from three different IWTEP harvesting points. The multiplex PCR amplicons showed that five isolates were positive for the bla gene marker and negative for the E. coli K-12 and api genes. The 16S rRNA regions of positive microorganisms carrying the bla gene were genotyped by the MicroSeq®500 system. The bacteria found were Escherichia spp (3/5), Chromobacterium spp (1/5), and Aeromonas spp (1/5). None of the 22 isolated microorganisms presented the molecular pattern of E. coli K-12 harboring the bla gene. The presence of microorganisms positive for the bla gene and negative for E. coli K-12 harboring bla genes at IWTEP suggests that the ampicillin resistance found in the isolated bacteria could be from microorganisms other than the E. coli K-12 strain harboring plasmid.
Assuntos
Resistência a Ampicilina/genética , Escherichia coli K12/genética , Marcadores Genéticos , Plasmídeos/genética , Águas Residuárias/microbiologia , Ampicilina/farmacologia , Antibacterianos/farmacologia , Brasil , Genes Bacterianos , Lagoas/microbiologia , RNA Ribossômico 16S , Serina Endopeptidases/genética , Instalações de Eliminação de Resíduos , Microbiologia da Água , Purificação da Água , beta-Lactamases/genéticaRESUMO
Enterotoxigenic Escherichia coli (ETEC) are major causes of childhood diarrhea in low and middle income countries including Colombia, South America. To understand the diversity of ETEC strains in the region, clinical isolates obtained from northern Colombia children were evaluated for multiple locus sequencing typing, serotyping, classical and nonclassical virulence genes, and antibiotic susceptibility. Among 40 ETEC clinical isolates evaluated, 21 (52.5%) were positive for LT gene, 13 (32.5%) for ST gene, and 6 (15%) for both ST and LT. The most prevalent colonization surface antigens (CS) were CS21 and CFA/I identified in 21 (50%) and 13 (32.5%) isolates, respectively. The eatA, irp2, and fyuA were the most common nonclassical virulence genes present in more than 60% of the isolates. Ampicillin resistance (80% of the strains) was the most frequent phenotype among ETEC strains followed by trimethoprim-sulfamethoxazole resistance (52.5%). Based on multiple locus sequencing typing (MLST), we recognize that 6 clonal groups of ETEC clinical isolates circulate in Colombia. ETEC clinical isolates from children in northern Colombia are highly diverse, yet some isolates circulating in the community belong to well-defined clonal groups that share a unique set of virulence factors, serotypes, and MLST sequence types.
Assuntos
Escherichia coli Enterotoxigênica/genética , Escherichia coli Enterotoxigênica/patogenicidade , Infecções por Escherichia coli/genética , Genótipo , Resistência a Ampicilina/genética , Toxinas Bacterianas/genética , Proteínas de Transporte/genética , Criança , Pré-Escolar , Colômbia/epidemiologia , Escherichia coli Enterotoxigênica/isolamento & purificação , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli/genética , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Recém-Nascido , Masculino , Peptídeo Hidrolases , Receptores de Superfície Celular/genética , Resistência a Trimetoprima/genéticaAssuntos
Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , beta-Lactamases/genética , Resistência a Ampicilina/genética , Brasil , DNA Bacteriano/genética , Humanos , Infecções por Klebsiella/microbiologia , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
We studied the genetic relationships between vancomycin-susceptible (n = 11) and -resistant Enterococcus faecium (VRE, n = 20) recovered from Brazil using a multilocus sequence typing (MLST) scheme. Grouping of allelic profiles revealed six clusters of related sequence types (STs) that differ in no more than two of the seven alleles. Of these, one cluster harbored 16 of the 20 isolates recovered during the first VRE outbreak in Brazil. The ampicillin and gentamicin resistance profiles were stable in the isolates that clustered within the groups I-III. Comparison with the allelic profiles of 139 E. faecium from different geographical regions and origins found in the international database http://www.mlst.net revealed that the Brazilian outbreak clone did not cluster in the previously named complex-17. This genetic complex contains hospital epidemic and clinical isolates recovered from different countries and continents. Twenty two of the 31 Brazilian isolates, including the VRE outbreak clone, clustered apart from the E. faecium isolates from the database, suggesting that these Brazilian isolates have a distinct evolutionary history.
Assuntos
Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana/genética , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/genética , Infecções por Bactérias Gram-Positivas/microbiologia , Alelos , Resistência a Ampicilina/genética , Brasil/epidemiologia , Contagem de Colônia Microbiana , Infecção Hospitalar/epidemiologia , Surtos de Doenças , Evolução Molecular , Gentamicinas/farmacologia , Infecções por Bactérias Gram-Positivas/epidemiologia , Hospitais , Humanos , Análise de Sequência de DNA , Resistência a Vancomicina/genéticaRESUMO
A promoter vector pACPR33 for Escherichia coli based on the promotorless ampicillin-resistance gene from pBR322 has been constructed. The promoter of the ampicillin-resistance gene was deleted and replaced by a suitable multiple cloning site. Molecular cloning of promoters into the polylinker resulted in activation of the ampicillin resistance in E. coli. The plasmid contains a functional origin of DNA replication and a tetracycline resistance gene for E. coli, and a chloramphenicol resistance gene for S. aureus. The vector permitted direct detection of promoter activity, especially strong promoters, by easy iodometric determination of beta-lactamase activity in liquid or solid media.
Assuntos
Escherichia coli/genética , Vetores Genéticos , Plasmídeos/genética , Regiões Promotoras Genéticas , Resistência a Ampicilina/genética , beta-Lactamases/metabolismoRESUMO
Forty Shigella flexneri strains isolated from children attended to at the Children's Hospital of Camagüey during an outbreak of acute diarrheal disease were studied; the minimal inhibitory concentration of ampicillin was determined. 33 strains (82.5%) were resistant to higher concentrations: 8 to 16 micrograms/mL, and 7 were susceptible to 4 micrograms/mL concentrations. Resistance plasmid (R) extraction was carried out in all the isolated strains and a common plasmid was found this plasmid was purified and transferred to Escherichia coli HE 101. Resistance transmission was tested.
Assuntos
Resistência a Ampicilina/genética , Fatores R/genética , Shigella flexneri/efeitos dos fármacos , Criança , Escherichia coli/genética , Humanos , Shigella flexneri/genética , Transformação Bacteriana/genéticaRESUMO
Se estudió por primera vez la sensibilidad de 92 cepas de Haemophilus influenzae tipo b, a diferentes antimicrobianos : ampicillina, cloranfenicol, rifampicina, ceftriaxone (rocephin) y cefotaxime (claforán), por el método de dilución en placas de agar. Se encontró una mayor resistencia de las cepas estudiadas frente al ampicillina (42,39 por ciento ) y al cloranfenicol (58,69 por ciento ) y una alta sesibilidad frente a la rifampicina (100 por ciento ), Ceftriaxone (100 por ciento ) y Cefotaxime (100 por ciento )
Assuntos
Resistência a Ampicilina/genética , Cefotaxima/farmacologia , Ceftriaxona/farmacologia , Cloranfenicol/farmacologia , Resistência Microbiana a Medicamentos/genética , Haemophilus influenzae/efeitos dos fármacos , Haemophilus influenzae/enzimologia , Técnicas In Vitro , Rifampina/farmacologiaRESUMO
The resistance to beta-lactam antibiotics shown by a strain of Shigella flexneri was plasmid-coded. This plasmid, pMAM-1, when transferred to Escherichia coli K-12 by conjugation, presented the same molecular weight (100 kbp) and conferred the same high level of resistance to ampicillin in the transconjugant as in the wild type strains (MIC, 2048-4096). Restriction analysis of the plasmid in transconjugants revealed various restrictive sites to some endonucleases (i.e. Bam HI, Eco RI, Pst I, Nco I, Cla I, Sf I and Sau 3AI, Nhe and Hin dIII), and no restrictive sites at all for other endonucleases (such as Xho I, Dra I, Kpn I, and Sal I). Some restricted DNA fragments were appropriate for cloning and isolation of the beta-lactamase gene present in Shigella flexneri UCSF 129. This work provides the first step in this direction.
Assuntos
Resistência a Ampicilina/genética , Resistência ao Cloranfenicol/genética , Plasmídeos/genética , Shigella flexneri/enzimologia , beta-Lactamases/genética , Plasmídeos/química , beta-Lactamases/biossínteseRESUMO
Plasmid pPG1 from Staphylococcus aureus coding for ampicillin (Apr), gentamicin (Gmr) and amikacin (Akr) resistance was transformed into Escherichia coli. Transformation efficiency was about 2 x 10(3) transformants/micrograms of plasmid DNA. The plasmids present in the E. coli transformants were identical to pPG1 according to their restriction patterns. The copy number of pPG1 was estimated to be at least 20-times less in E. coli than in S. aureus. The minimal inhibitory concentrations (MICs) for Ap and Gm were lower in E. coli than in S. aureus. However, the MIC for Ak was higher in E. coli transformants than in S. aureus. pPG1 was maintained in the E. coli transformants for at least 80 generations at 37 degrees C without antibiotic selection pressure.