RESUMEN
An indirect ELISA was used to detect antibodies against outer membrane protein preparations (OMPs) from Salmonella typhi. Sera from patients with a definitive diagnosis of typhoid fever (TF) gave a mean absorbance reading, at 414 nm, of 1.52 +/- 0.23 as compared to 0.30 +/- 0.11 for sera from healthy individuals. This gave a positive to negative ratio of absorbance readings of approximately 5.1. Suspected TF patients (no isolation of S. typhi), with positive and negative Widal titers had mean absorbance readings of 1.282 +/00.46 and 0.25 +/- 0.19, respectively. Sera from patients with leptospirosis, rickettsial typhus, dengue fever, and other infections gave mean absorbances of 0.20 +/- 0.08, 0.24 +/- 0.08, 0.27 +/- 0.08, and 0.31 +/- 0.16, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 94%, 80% and 100%, respectively. The antibody response detected in the definitive TF cases was predominantly IgG in nature and no cross-reactivity was seen with OMP preparations extracted from E. coli. Variable reactivity was noted with OMP preparations obtained from other Salmonella spp. Three major OMPs are presented in the antigen preparation and strong binding of positive sera was detected to all three bands.
Asunto(s)
Anticuerpos Antibacterianos/análisis , Infecciones Bacterianas/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Reacciones Cruzadas , Electroforesis en Gel de Poliacrilamida , Ensayo de Inmunoadsorción Enzimática , Escherichia coli/inmunología , Reacciones Falso Positivas , Humanos , Immunoblotting , Inmunoglobulina G/inmunología , Valor Predictivo de las Pruebas , Salmonella typhi/inmunología , Sensibilidad y Especificidad , Fiebre Tifoidea/diagnósticoRESUMEN
Four of the five veterinary E. coli strains, which were unable to transfer their antibiotic resistance by conjugation, were found to harbour plasmids. Evidence from transformation, agarose gel electrophoresis and curing experiments showed that in strains KE-3, KE-4 and KE-14 a nonconjugative R plasmid carried the gene for resistance to tetracycline. The plasmids in KE-9 were cryptic.
Asunto(s)
Animales , Antibacterianos/farmacología , Conjugación Genética , Electroforesis en Gel de Agar , Escherichia coli/efectos de los fármacos , Malasia , Factores R , Tetraciclina/farmacología , Transformación BacterianaRESUMEN
Fifteen independent E. coli strains of avian, bovine and porcine origin in Peninsular Malaysia were tested for antibiotic resistance and conjugative R plasmids. Eight (53%) isolates were found to be antibiotic resistant. Among them, 37.5% were mono-resistant and 62.5% were resistant to three or more antibiotics, i.e., multi-resistant. All of them were resistant to Tc and sensitive to Gm and Nx. Three of the eight antibiotic resistant strains were able to transfer all or part of their resistance to an E. coli K12 recipient by conjugation. The transfer frequencies of Km, Sm and Tc resistance of the three donors varied between 4.5 X 10(-8) to 6.8 X 10(-7). Analysis of the plasmid profiles of all the three donors and their respective transconjugants after agarose gel electrophoresis provided conclusive evidence that the transferable resistance traits were plasmid-mediated.
Asunto(s)
Animales , Antibacterianos/farmacología , Bovinos , Conjugación Genética/efectos de los fármacos , Farmacorresistencia Microbiana , Escherichia coli/efectos de los fármacos , Infecciones por Escherichia coli/tratamiento farmacológico , Malasia , Plásmidos/efectos de los fármacos , Aves de Corral , PorcinosRESUMEN
Six independent isolates of Klebsiella from hospital environmental sources in Malaysia were found to be resistant to at least ampicillin, carbenicillin, cefoperazone, chloramphenicol, gentamicin and tetracycline. On the basis of their antibiograms, they were divided into four antibiogroups. They transferred all or part of their multiple antibiotic resistance traits to E. coli by conjugation. The results suggest that these Klebsiella strains harbour self-transmissible R plasmids. The significance of these findings are discussed.