RESUMO
Previous studies on commensal Escherichia coli from healthy children in the Bolivian Chaco have shown remarkable resistance rates to the old antibiotics since the early 1990s, and the emergence of resistance to newer drugs (fluoroquinolones and expanded-spectrum cephalosporins) in the 2000s. Here we report the results of a new survey conducted in 2011 in the same setting. Rectal swabs were obtained from 482 healthy children (aged 6-72 months) from three urban areas of the Bolivian Chaco. Screening for antibiotic-resistant E. coli was performed by a direct plating method, as in the previous studies. The blaCTX-M genes were investigated by PCR/sequencing, and CTX-M-producing isolates were subjected to genotyping and detection of several plasmid-mediated quinolone resistance mechanisms. Results showed high rates of resistance to nalidixic acid (76%), ciprofloxacin (44%) and expanded-spectrum cephalosporins (12.4%), demonstrating a relentless increase of resistance to those drugs over the past two decades. CTX-M-type extended-spectrum beta-lactamases were found to be widespread (12%, 97% of extended-spectrum beta-lactamase producers). Compared with the previous studies, CTX-M-producing E. coli underwent a dramatic dissemination (120-fold increase since early 2000s) and a radical change of dominant CTX-M groups (CTX-M-1 and CTX-M-9 groups versus CTX-M-2 group). Most CTX-M producers were not susceptible to quinolones (91%), and 55% carried plasmid-mediated quinolone resistance genes (different combinations of aac(6')-Ib-cr, qnrB and qepA). This study shows the rapid and remarkable increasing trend for resistance to fluoroquinolones and expanded-spectrum cephalosporins in one of the poorest regions of Latin America, and underscores the need for urgent control strategies aimed at preserving the efficacy of those drugs in similar settings.
Assuntos
Antibacterianos/farmacologia , Cefalosporinas/farmacologia , Farmacorresistência Bacteriana , Infecções por Escherichia coli/epidemiologia , Escherichia coli/efeitos dos fármacos , Fluoroquinolonas/farmacologia , Bolívia/epidemiologia , Criança , Pré-Escolar , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Feminino , Genótipo , Humanos , Lactente , Masculino , Testes de Sensibilidade Microbiana , Plasmídeos/análise , Reação em Cadeia da Polimerase , Reto/microbiologia , Análise de Sequência de DNARESUMO
A multicenter survey, carried out in 2010 in Argentina, showed an increased prevalence of extended-spectrum ß-lactamase (ESBL)-producing enterobacteria, with some changes in the molecular epidemiology of circulating ESBLs. While enzymes of the CTX-M-2 group remain endemic, the emergence of CTX-M-15 and of enzymes of the CTX-M-8 and CTX-M-9 groups was observed. The CTX-M-15-positive isolates represented 40% of CTX-M producers and included representatives of Escherichia coli ST131 and Klebsiella pneumoniae ST11.
Assuntos
Infecções por Escherichia coli/tratamento farmacológico , Escherichia coli/efeitos dos fármacos , Infecções por Klebsiella/tratamento farmacológico , Klebsiella pneumoniae/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Argentina/epidemiologia , Escherichia coli/genética , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , Heterogeneidade Genética , Humanos , Infecções por Klebsiella/epidemiologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/genética , Resistência beta-Lactâmica/efeitos dos fármacos , beta-Lactamases/metabolismo , beta-Lactamas/farmacologia , beta-Lactamas/uso terapêuticoRESUMO
Twelve Klebsiella pneumoniae isolates resistant to expanded-spectrum cephalosporins and aztreonam, from patients with nosocomial septicaemia at the intensive care unit of the Andes University Hospital, Mérida, Venezuela, were studied for production of extended-spectrum beta-lactamase (ESbetaL) activity. All were also resistant to gentamicin, kanamycin, tetracycline and chloramphenicol but sensitive to cefoxitin, imipenem, amikacin and tobramycin. Production of ESbetaL activity was confirmed by restoring susceptibility to ceftazidime in the presence of clavulanic acid. All isolates carried an identical plasmid of approximately 87 kb. Resistance to beta-lactams, aminoglycosides, tetracycline and chloramphenicol was lost en bloc after plasmid curing by treatment with acridine orange and was transferable en bloc to Escherichia coli by conjugation. Transconjugants always showed the same plasmid profile as that of Klebsiella donors. Isoelectric focusing analysis of the crude extracts of transconjugants showed in all cases, the presence of two beta-lactamases of pI 5.4 and 8.2. Analysis of the plasmid carried by one of the transconjugants by means of hybridization assays, revealed the presence of both bla(TEM) and bla(SHV) determinants. Cloning and sequencing of each determinant identified them as bla(TEM-1) and bla(SHV-5), respectively, the latter being responsible for the ESbetaL activity. Results of this study indicate that ESbetaL determinants of the SHV-type carried by transferable elements, are spreading among nosocomial isolates of K. pneumoniae in Mérida, Venezuela.
Assuntos
Infecção Hospitalar/microbiologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/enzimologia , beta-Lactamases/biossíntese , Antibacterianos/farmacologia , Infecção Hospitalar/epidemiologia , Humanos , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Plasmídeos , Venezuela/epidemiologiaRESUMO
A genomic library from Burkholderia cepacia IS-16 was constructed in Escherichia coli by partial Sau3AI digestion of the chromosomal DNA, with the plasmid vector Bluescript SK. This library was screened for clones able to grow as green stained colonies on selective medium developed for detecting phosphatase-positive colonies. Three green-stained clones (pFS1, pFS2, and pFS3) carried recombinant plasmids harboring DNA inserts of 5.0, 8.0, and 0.9 kb, respectively. DNA hybridization experiments demonstrated the presence of overlapping DNA fragments in the three clones and that these three clones were all derived from Burkholderia cepacia IS-16 genomic DNA. DNA sequence analysis, together with polyacrylamide gels of proteins encoded by E. coli containing pFS3, suggested that the isolated 0. 9-kb DNA fragment encodes the functional portion of a phosphate transport protein.
Assuntos
Proteínas da Membrana Bacteriana Externa/genética , Burkholderia cepacia/genética , Genes Bacterianos , Monoéster Fosfórico Hidrolases/genética , Sequência de Aminoácidos , Sequência de Bases , Burkholderia cepacia/enzimologia , Escherichia coli/genética , Biblioteca Gênica , Vetores Genéticos , Dados de Sequência Molecular , PlasmídeosRESUMO
Aeromonas spp. are increasingly being recognized as human pathogens. The presence of metallo-beta-lactamases in these organisms represents a potential problem in antimicrobial therapy. Mechanism-based inactivators of beta-lactamases are used to overcome the resistance of clinical pathogens to beta-lactam antibiotics, but no clinical useful inhibitors of the metallo-beta-lactamases are presently known. Studying the interaction between cefotetan and Aeromonas spp. producing metallo-beta-lactamase activity, we observed that cefotetan behaved as a transient inactivator for both the crude extracts of Aeromonas strains and the purified enzymes from Aeromonas hydrophila AE036 and Aeromonas schubertii MNSA20. The direct hydrolysis of cefotetan showed that it was a poor substrate for both purified enzymes. In view of the minimum inhibitory concentrations, cefotetan shows to be a useful antimicrobial agent against Aeromonas spp.
Assuntos
Aeromonas/efeitos dos fármacos , Aeromonas/enzimologia , Proteínas de Bactérias , Cefotetan/farmacologia , Cefamicinas/farmacologia , Metaloproteínas/metabolismo , beta-Lactamases/metabolismo , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/enzimologia , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Metaloproteínas/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Inibidores de beta-Lactamases , beta-Lactamases/efeitos dos fármacosRESUMO
A total of 47 strains of Aereomonas isolated from patients with gastroenteritis was analyzed for 40 phenotypical characters and for evaluating the numeric taxonomy based on 27 discriminatory tests. It was proved that the clinical isolates showed a relative phenotypical distance and the groups of strains that had atypical profiles were compared with the type species by the present identification schemes.