Asunto(s)
Heces/microbiología , Infecciones por Helicobacter/diagnóstico , Helicobacter pylori/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Adolescente , Adulto , Antígenos Bacterianos/aislamiento & purificación , Estudios de Factibilidad , Femenino , Helicobacter pylori/inmunología , Humanos , Masculino , Tamizaje Masivo/métodos , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa/normasRESUMEN
Bovine mastitis Staphylococcus aureus isolates and prototypic live-attenuated vaccine strains were analyzed by SmaI pulsed-field gel electrophoresis (PFGE) typing and automated ribotyping. The discriminatory index of these methods was 0.91 and 0.69, respectively. SmaI PFGE typing assigned all laboratory strains into cluster Q, which shared 49% similarity with clusters A and B, and 35% similarity with cluster C. Automated ribotyping placed laboratory strains within ribogroups different from those of bovine isolates. These methods have 70% concordance and permitted identification of the prototypic vaccine background from those of clinical isolates. This information is required before conducting field trials with the vaccine.
Asunto(s)
Mastitis Bovina/microbiología , Ribotipificación/métodos , Ribotipificación/normas , Staphylococcus aureus/clasificación , Staphylococcus aureus/aislamiento & purificación , Vacunas Atenuadas/clasificación , Vacunas Atenuadas/aislamiento & purificación , Animales , Bovinos , Ensayos Clínicos como Asunto , ADN Bacteriano/análisis , ADN Bacteriano/genética , Electroforesis en Gel de Campo Pulsado , Evolución Molecular , Genotipo , Epidemiología Molecular/métodos , Epidemiología Molecular/normas , Reproducibilidad de los Resultados , Mapeo Restrictivo , Staphylococcus aureus/genética , Vacunas Atenuadas/genéticaRESUMEN
Staphylococcus aureus is the most prevalent pathogen causing mastitis of dairy ruminants. This study was developed to ascertain the genotypes and genealogical relationship among strains isolated from milk of bovines with mastitis in Argentina. Molecular epidemiological analysis of S. aureus was performed on 112 isolates from 21 districts. Clonality was assessed by SmaI pulsed-field gel electrophoresis (PFGE) typing, automated EcoRI ribotyping and restriction enzyme analysis of plasmid (REAP) DNA profiles. A total of 22 band patterns distributed in four clusters were found by SmaI PFGE analysis. The similarity of clusters 2, 3 and 4 with cluster 1 was 0.73, 0.69 and 0.33, respectively, and 101 of 112 isolates belonged in cluster 1. PFGE band patterns from 42 isolates within cluster I were indistinguishable from each other (type A). The second largest group of isolates with indistinguishable PFGE band patterns was subtype A11, which was composed of 19 isolates. Automated ribotyping assigned the 112 isolates into 13 ribotypes. Among these, the most prevalent ribotypes I and VI were composed of 49 and 35 isolates respectively. Although there was certain correspondence between PFGE genotypes and ribotypes, further discrimination was achieved by combining both methods. REAP DNA profile analysis was useful to provide even further discrimination between isolates with identical PFGE genotype and ribotype. The most prevalent S. aureus strains A/I and A11/VI were widely distributed in the country and were not restricted to individual nearby locations. Prevalence of these two strains varied consecutively within a period of 8 years. Whether the shift in type prevalence was due to selection of a phenotypic trait remains undisclosed.
Asunto(s)
Industria Lechera , Electroforesis en Gel de Campo Pulsado/normas , Mastitis Bovina/microbiología , Leche/microbiología , Ribotipificación/normas , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/genética , Animales , Argentina/epidemiología , Bovinos , Análisis por Conglomerados , Dermatoglifia del ADN/normas , ADN Bacteriano/genética , Análisis Discriminante , Femenino , Genotipo , Mastitis Bovina/epidemiología , Epidemiología Molecular/métodos , Epidemiología Molecular/normas , Filogenia , Vigilancia de la Población , Prevalencia , Mapeo Restrictivo/normas , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureus/clasificaciónRESUMEN
Non-O1 strains of Vibrio cholerae implicated in gastroenteritis and diarrhea generally lack virulence determinants such as cholera toxin that are characteristic of epidemic strains; the factors that contribute to their virulence are not understood. Here we report that at least one-third of diarrhea-associated nonepidemic V. cholerae strains from Mexico cause vacuolation of cultured Vero cells. Detailed analyses indicated that this vacuolation was related to that caused by aerolysin, a pore-forming toxin of Aeromonas; it involved primarily the endoplasmic reticulum at early times (approximately 1 to 4 h after exposure), and resulted in formation of large, acidic, endosome-like multivesicular vacuoles (probably autophagosomes) only at late times (approximately 16 h). In contrast to vacuolation caused by Helicobacter pylori VacA protein, that induced by V. cholerae was exacerbated by agents that block vacuolar proton pumping but not by endosome-targeted weak bases. It caused centripetal redistribution of endosomes, reflecting cytoplasmic alkalinization. The gene for V. cholerae vacuolating activity was cloned and was found to correspond to hlyA, the structural gene for hemolysin. HlyA protein is a pore-forming toxin that causes ion leakage and, ultimately, eukaryotic cell lysis. Thus, a distinct form of cell vacuolation precedes cytolysis at low doses of hemolysin. We propose that this vacuolation, in itself, contributes to the virulence of V. cholerae strains, perhaps by perturbing intracellular membrane trafficking or ion exchange in target cells and thereby affecting local intestinal inflammatory or other defense responses.
Asunto(s)
Proteínas Hemolisinas/toxicidad , Vacuolas , Vibrio cholerae/patogenicidad , Adulto , Proteínas Bacterianas , Clonación Molecular , Diarrea/microbiología , Escherichia coli/genética , Femenino , Gastroenteritis/microbiología , Proteínas Hemolisinas/genética , Humanos , México , Presión Osmótica , Especificidad de la Especie , Pruebas de Toxicidad , Vibrio cholerae/clasificaciónRESUMEN
Inexpensive, rapid, and reliable methods of detecting infection by and drug susceptibility of Mycobacterium tuberculosis (MTB) are crucial to the control of tuberculosis. The novel microscopic observation broth-drug susceptibility assay (MODS) detects early growth of MTB in liquid medium, allowing more timely diagnosis and drug susceptibility testing. Sputum samples from hospitalized patients in Peru were analyzed by using stains, culture, and PCR. Sensitivity of MODS (92%) compared favorably with the most sensitive of the other culture methods (93%). Sputum samples positive for tuberculosis were tested for susceptibility to isoniazid and rifampin with the microwell alamar blue assay (MABA) and MODS. In 89% of cases, there was concordance between MODS and MABA. Of the diagnostic and susceptibility testing methods used, MODS yielded results most rapidly (median, 9.0 and 9.5 days, respectively). MODS is a rapid, inexpensive, sensitive, and specific method for MTB detection and susceptibility testing; it is particularly appropriate for use in developing countries burdened by significant infection rates and increasing numbers of multiple-drug-resistant cases.
Asunto(s)
Antituberculosos/farmacología , Mycobacterium tuberculosis/efectos de los fármacos , Mycobacterium tuberculosis/aislamiento & purificación , Esputo/microbiología , Tuberculosis/diagnóstico , Técnicas de Tipificación Bacteriana , Costos y Análisis de Costo , Farmacorresistencia Microbiana , Humanos , Pacientes Internos , Isoniazida/farmacología , Pruebas de Sensibilidad Microbiana/economía , Pruebas de Sensibilidad Microbiana/métodos , Mycobacterium tuberculosis/crecimiento & desarrollo , Perú , Reacción en Cadena de la Polimerasa/métodos , Reproducibilidad de los Resultados , Rifampin/farmacología , Sensibilidad y EspecificidadRESUMEN
Staphylococcus aureus is an important cause of bovine mastitis worldwide, and effective preventive or therapeutic modalities are lacking. Although most human S. aureus isolates produce capsular polysaccharides (CPs), few reports have described the prevalence of capsules on bovine isolates. This information is important for the rational design of a vaccine for the prevention of staphylococcal mastitis. We serotyped 195 S. aureus strains isolated between 1989 and 1997 from the milk of mastitic cows in Argentina. Only 14 (7.1%) of the strains were serotype 5, and all were recovered between 1989 and 1992. Thirteen serotype 8 strains were identified, and 12 of these were isolated between 1991 and 1994. The remaining 168 isolates were nonreactive (NR) with CP serotype 5 (CP5)- or CP8-specific antibodies. Hybridization studies performed with genomic DNA from eight NR strains revealed that only three of them carried the capsule genes. Pulsed-field gel electrophoresis (PFGE) performed with 127 of the 195 S. aureus isolates revealed that most (86%) strains belonged to one of four major PFGE groups. Although 8 of 14 CP5 isolates showed a common PFGE pattern (arbitrarily defined as A1), 31 other A1 isolates from the same time period (1989 to 1992) were not CP5 positive. In contrast, only nine PFGE type B3 isolates were recovered between 1990 and 1994, and eight of these were positive for CP8 (P < 0.0003). The results of this study underscore the variability in capsule expression by S. aureus strains isolated from different geographical regions and cast doubt on the roles of CP5 and CP8 in the pathogenesis and immunoprophylaxis of bovine mastitis in Argentina.
Asunto(s)
Cápsulas Bacterianas/genética , Mastitis Bovina/epidemiología , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/clasificación , Staphylococcus aureus/metabolismo , Animales , Argentina/epidemiología , Cápsulas Bacterianas/metabolismo , Bovinos , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/microbiología , Electroforesis en Gel de Campo Pulsado , Femenino , Mastitis Bovina/microbiología , Leche/microbiología , Hibridación de Ácido Nucleico , Prevalencia , Serotipificación , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/genéticaRESUMEN
Helicobacter pylori is an extremely diverse species. The characterization of strains isolated from individual patients should give insights into colonization and disease mechanisms and bacterial evolution. We studied H. pylori isolates from patients in the Japanese-Peruvian Polyclinic in Lima, Peru, by determining metronidazole susceptibility or resistance and by random amplified polymorphic DNA (RAPD) fingerprinting (a measure of overall genotype). Strains isolated from several biopsy specimens from each of 24 patients were studied. Both metronidazole-susceptible and -resistant strains were isolated from 13 patients, whereas strains of more than one RAPD type were isolated from only seven patients. We propose that the homogeneity in RAPD fingerprints for strains isolated from most persons reflects selection for particular H. pylori genotypes during chronic infection in individual hosts and the human diversity in traits that are important to this pathogen. Carriage of related metronidazole-resistant and -susceptible strains could reflect frequent metronidazole use in Peru and alternating selection for resistant and susceptible phenotypes during and after metronidazole therapy.
Asunto(s)
Infecciones por Helicobacter/microbiología , Helicobacter pylori , Adulto , Anciano , Antibacterianos/farmacología , Dermatoglifia del ADN , Farmacorresistencia Microbiana/genética , Femenino , Infecciones por Helicobacter/epidemiología , Helicobacter pylori/efectos de los fármacos , Helicobacter pylori/genética , Helicobacter pylori/aislamiento & purificación , Humanos , Masculino , Metronidazol/farmacología , Persona de Mediana Edad , Perú/epidemiología , Técnica del ADN Polimorfo Amplificado AleatorioRESUMEN
Resistance of Helicobacter pylori to metronidazole often causes failure of commonly used combination drug treatment regimens. We determined the MICs of metronidazole and clarithromycin against 18 H. pylori strains from Peru using tetrazolium egg yolk (TEY) agar. The MIC results obtained by agar dilution with petri dishes were compared with the results found through a miniwell format. The results of the two protocols for measuring drug susceptibility differed by no more than 1 dilution in all cases. On TEY agar, bright-red H. pylori colonies were easy to identify against a yellow background. Sixty-one percent (11 of 18) of the strains were resistant to metronidazole (MIC, > or = 4 micrograms/ml) and 50% (9 of 18) were resistant to clarithromycin (MIC, > or = 0.125 micrograms/ml), whereas none (0 of 5) of the strains tested were resistant to tetracycline (MIC, > or = 1 micrograms/ml). Thus, the prevalence of metronidazole and clarithromycin resistance in Peru is higher than that in developed regions of the world. The miniwell plate with TEY agar allows easy H. pylori colony identification, requires about one-third less of the costly medium necessary for petri dish assaying, conserves space, and yields MICs equivalent to those with agar dilution in petri dishes.
Asunto(s)
Claritromicina/farmacología , Helicobacter pylori/efectos de los fármacos , Metronidazol/farmacología , Pruebas de Sensibilidad Microbiana/métodos , Agar , Antibacterianos/farmacología , Color , Países en Desarrollo , Farmacorresistencia Microbiana , Estudios de Evaluación como Asunto , Infecciones por Helicobacter/tratamiento farmacológico , Infecciones por Helicobacter/microbiología , Helicobacter pylori/aislamiento & purificación , Humanos , Indicadores y Reactivos , Pruebas de Sensibilidad Microbiana/estadística & datos numéricos , Perú , Reproducibilidad de los ResultadosRESUMEN
We tested the effectiveness of specific vs. general infection control interventions in a teaching hospital in Guatemala City. After 3 months of prospective surveillance, we implemented targeted interventions (i.e., modification of respiratory tract care and use of a closed urinary catheter drainage system), an educational program focused on respiratory intervention, and general interventions (i.e., aseptic technique). The rate of nosocomial pneumonia, the most common nosocomial infection, decreased from 33% (41 of 123 patients) before intervention to 16% (21 of 130 patients) after intervention (P = .001). Although the frequency of hand washing increased from 5% to 63% (P < .001), the rates of other types of nosocomial infections did not change significantly. The combination of targeted respiratory intervention and an intense, focused educational campaign reduced the rate of nosocomial pneumonia. General improvements in hygiene and hand washing rates, or even implementation of a closed urinary drainage system without focused education, may not be sufficient to reduce infection rates in intensive care units in developing countries.