RESUMO
This study aimed to identify and characterize integrons among multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC) from outpatients in Mexico City, Mexico. PCR assays were used to screen for the presence of class 1, 2 and 3 integrons, whose PCR products were sequenced to identify the inserted gene cassettes within the variable regions. Out of 83 tested strains, 53 (63.9%) were positive for the presence of class 1 integrons, whereas no integrons were detected in the remaining strains, regardless of their classes. Most of the strains carrying the intI1 gene belonged to the extraintestinal B2 (41.5%) and commensal A (32.1%) phylogroups, and to a lesser extent, the extraintestinal D (20.8%) and commensal B1 (5.7%) phylogroups. Moreover, 8 different gene cassette arrangements were detected, with dfrA17 and aadA5 being the most common (32.1% of the class 1 integron-positive strains), which confer resistance to trimethoprim/sulfamethoxazole and aminoglycosides, respectively. Our results suggest that class 1 integrons are widely distributed among MDR-UPEC strains in Mexico, which may directly or indirectly contribute to the selection of MDR strains. These findings are important for a better understanding of the factors and mechanisms that promote multidrug resistance among UPEC strains.
Assuntos
Infecções por Escherichia coli , Escherichia coli Uropatogênica , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Humanos , Integrons/genética , México , Escherichia coli Uropatogênica/genéticaRESUMO
The O25-ST131 clone was identified within 169 uropathogenic Escherichia coli (UPEC) strains. The 44.8% of the 29 O25-ST131 clones detected were positive to least to one extended-spectrum ß-lactamase gene. The phylogroup D was mainly found. The O25-ST131 clone appeared to be associated with community-acquired UTI in Mexico City.
Assuntos
Infecções Comunitárias Adquiridas/microbiologia , Genótipo , Sorogrupo , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/classificação , Escherichia coli Uropatogênica/isolamento & purificação , Adolescente , Adulto , Idoso , Infecções Comunitárias Adquiridas/epidemiologia , Humanos , México/epidemiologia , Pessoa de Meia-Idade , Infecções Urinárias/epidemiologia , Adulto Jovem , beta-Lactamases/genéticaRESUMO
INTRODUCTION: The increasing prevalence of uropathogenic Escherichia coli (UPEC) strains resistant to multiple antibiotics complicates the treatment of urinary tract infections (UTIs). This study aimed to analyze the antimicrobial resistance, serotypes, and phylogenetic groups among strains of E. coli isolated from outpatients with UTIs in Mexico City. METHODOLOGY: A total of 119 E. coli isolates were recovered from urine samples from outpatients with clinical diagnosis of uncomplicated UTIs from 2004 to 2007. The serotype was assessed by agglutination in microtiter plates; susceptibility to antimicrobials was determined by the disk diffusion method. Clone O25-ST131 and phylogenetic groups of E. coli strains were tested by methods based on PCR multiplex. RESULTS: The predominant serotype was O25:H4 (21.2%). Resistance to antibiotics was ampicillin (83.7%); piperacillin (53.8%); the fluoroquinolone group (55.5-60.6%), and trimethoprim/sulfamethoxazole (TMP/SMX) (56.4%). Additionally, 36 (30.2%) isolates were multidrug-resistant and 13 of these 36 strains were identified as E. coli O25-ST131 clone by an allele-specific PCR-based assay. Phylogenetic analysis showed that 15 of 17 isolates with serotype O25:H4 belonged to group B2. CONCLUSIONS: This is the first report that establishes the presence in Mexico of the O25-ST131 clonal group of E. coli, which has been associated with multidrug-resistance and with high virulence potential. The spread of this clone in Mexico should be monitored closely. We found a correlation between serotype O25:H4 and multidrug resistance in UPEC strains. Our results indicate that the use of ampicillin, fluoroquinolones, and TMP/SMX should be reviewed when selecting empirical therapy for UTIs.
Assuntos
Farmacorresistência Bacteriana , Infecções por Escherichia coli/epidemiologia , Tipagem Molecular , Sorotipagem , Infecções Urinárias/epidemiologia , Escherichia coli Uropatogênica/classificação , Escherichia coli Uropatogênica/isolamento & purificação , Adolescente , Adulto , Idoso , Testes de Aglutinação , Análise por Conglomerados , Infecções por Escherichia coli/microbiologia , Feminino , Humanos , Masculino , México/epidemiologia , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Epidemiologia Molecular , Reação em Cadeia da Polimerase Multiplex , Filogenia , Infecções Urinárias/microbiologia , Adulto JovemRESUMO
Some enteropathogenic Escherichia coli (EPEC) strains, which are an important cause of diarrhea among infants, secrete a serine protease autotransporter protein called EspC. The pathogenic role of EspC upon EPEC infection is unknown. In this study, we demonstrated that purified EspC protein, obtained from supernatants of EPEC cultures, interacted with hemoglobin and degraded it. Moreover, we have shown that EspC is a hemin-binding protein. We hypothesized that hemoglobin proteolysis by EspC may contribute to the utilization of heme and hemoglobin iron for bacterial growth.
Assuntos
Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Hemoglobinas/metabolismo , Serina Endopeptidases/sangue , Proteínas de Transporte/sangue , Proteínas de Transporte/metabolismo , Proteínas de Escherichia coli/isolamento & purificação , Proteínas Ligantes de Grupo Heme , Hemeproteínas/metabolismo , Hemina/metabolismo , Humanos , Serina Endopeptidases/metabolismoRESUMO
Secretory and systemic antibody response in mice against enteropathogenic Escherichia coli (EPEC) was evaluated. Groups of mice were immunized with formalin inactivated EPEC 0127:H6 strain by intranasal, peroral, intragastric and intrarectal route, with and without cholera toxin (CT) used as mucosal adjuvant. Mice immunized subcutaneously and a non treated control group were included. Other groups of mice were immunized intranasally with different EPEC strains and a non pathogenic E. coli K12 strain. Antibody response tested by ELISA assay showed that specific anti EPEC 0127:H6 antibodies were induced in serum by intranasal, subcutaneous and intragastric routes. A strong increase of antibody response against EPEC 0127:H6 strain was observed in saliva after intranasal delivery, while a lower response was detected by peroral and intrarectal immunization. Only the intranasal route increased IgA anti EPEC 0127:H6 antibody titers in feces. Specific and cross reactive antibodies to EPEC 0127:H6 were seen in mice immunized intranasally with different EPEC strains. Some control mice showed a background of anti EPEC 0127:H6 antibodies in feces. CT had a negative effect as adjuvant. We showed that nasal mucosa rendered the strongest antibody response in serum and secretions. These results might contribute to optimize the protective effect of enteric vaccines against infections associated to EPEC.