Comparación de diferentes métodos para identificar las especies del género Proteus / Comparison of different methods in order to identify Proteus spp

Los objetivos de este trabajo fueron: a) identificar a nivel de especie aislamientos de Proteus siguiendo la combinación de los esquemas de Farmer y O'Hara; b) determinar la utilidad del sistema comercial API 20E y de un esquema reducido de pruebas (agar TSI y agar MIO: movilidad, indol y ornitina), comparar estos procedimientos con la metodología convencional y evaluar su sensibilidad y especificidad, y c) evaluar la utilidad del perfil proteico en la identificación de las distintas especies. Se estudiaron 205 aislamientos de Proteus spp. aislados en el período comprendido entre enero de 1998 y setiembre de 2004, recuperados de distintos materiales clínicos correspondientes a pacientes hospitalizados y ambulatorios atendidos en el Hospital de Clínicas. Los organismos fueron identificados mediante la metodología convencional, por el sistema API 20E y con un esquema reducido de pruebas; 48 de ellos fueron sometidos a un SDS-PAGE. API 20E identificó 79 de 87 aislamientos de P. mirabilis (90,8%), 103/103 del complejo P. vulgaris y 15/15 de P. penneri. Ocho aislamientos identificados como Proteus spp. resultaron ser P. mirabilis, al incluir una prueba adicional (maltosa). En la identificación, el esquema reducido coincidió en un 100% con la metodología convencional. A diferencia del sistema API 20E, el esquema reducido alcanza la correcta identificación de todas las especies en laboratorios de baja complejidad, sin la necesidad de pruebas adicionales. El perfil proteico permitió la correcta diferenciación de las tres especies, independientemente de las diferentes atipias de P. mirabilis.

The objectives were: a) to identify Proteus strains to species level, following Farmer's and O'Hara's conventional biochemical reactions; b) to evaluate the sensitivity and specificity of both the API 20E method and a schema of reduced reactions (TSI and MIO agar: motility, indole and ornithine) comparing them with conventional methodology, and c) to evaluate the utility of SDS-PAGE (total proteins) in order to identify Proteus strains to species level. Two hundred and five Proteus spp. clinical isolates, were collected between January 1998 and September 2004, from inpatients and outpatients at Hospital de Clínicas. Strains were identified by means of conventional methodology, the API 20E method, and a schema of reduced reactions. SDS-PAGE (total proteins) was used in 48 out of the 205 strains. The API 20E method identified 79 out of 87 (90.8%) strains of P. mirabilis, 103 out of 103 P. vulgaris complex, and 15 out of 15 P. penneri. Eight strains of P. mirabilis were identified as Proteus spp., the acid production from maltose being necessary to identify them to species level. The schema of reduced reactions identified 205 out of 205 (100%) strains, that is, this schema of reduced reactions identified all the strains to species level without any additional tests, in marked contrast to the API 20E method. The SDS-PAGE (total proteins) identified the three species of the genus, even if the strains of P. mirabilis showed different biochemical reactions.

Análisis de una cepa de Yersinia enterocolitica aislada de heces diarreicas humanas en Argentina / Analysis of a Yersinia enterocoliticaisolated from human diarreic feces in Argentina

Algunos serotipos de Yersinia enterocolitica ocasionan desde diarreas hasta infecciones invasivas. El objetivo del trabajo fue analizar factores de virulencia y marcadores asociados en una cepa de Y. enterocolitica aislada de heces diarreicas humanas. El aislamiento deY. enterocolitica analizado fue incluído dentro del sub-grupo 1A.La determinación de resistencia al suero humano normal e hidrofobicidad de superficie, así como la búsqueda de los genes vir F y ail, resultaron negativos. Se demostró sin embargo producción de enterotoxina a 20 °C y también a 37 °C en condiciones de osmolaridad y pH similares a las del intestino humano. La enterotoxina, presentó reactividadpor la prueba del ratón lactante, aunque no se pudo comprobarpor PCR la presencia del gen yst. Los resultados obtenidos por nosotros, coincidentes con los de otros investigadores, indican que ciertos aislamientos clínicos de Y. enterocolitica del biotipo 1A (“avirulentas”), son capaces de causar enfermedad, probablemente a través de otros mecanismos, distintos a los caracterizados en especies de Yersinia enteropatógenas.

Some serotypes of Yersinia enterocoliticamight causediarrheas and/or invasive infections. The aim of this work was to analyze virulence factors and associated markers in a strain of Y. enterocolitica isolated from human diarrheic feces. The strain analyzed was included in the biotype 1A. The virulence markers determinationas well as the search of the genes vir F and ail,were negatives. However, it was demonstratedenterotoxin production at 20 °C, andat 37 °C in osmolarity conditions and pH similar to the human intestine. The enterotoxin presented reactivity for the infant mouse test, although it could not be proven the presence of yst gene by PCR. The results obtained by us, coincident with those of other investigators,indicated that certain clinical isolates of Y. enterocolitica of the biotype 1A (“avirulent”), could be the etiological agent of the illness trhough other mechanisms of virulence, that would differ from those previously characterized in species of enteropathogenic Yersinia.

Desinfección de agua: acción comparativa del ozono y cloro sobre un amplio espectro bacteriano / [Water disinfection: comparative activities of ozone and chlorine on a wide spectrum of bacteria]

Ozone and chlorine are agents that disinfect by destroying, neutralizing or inhibiting the growth of pathogenic microorganisms. The treatment of drinking water with ozone has shown to be more efficient against spores of Bacillus subtilis. It was observed that the ozone already in dose of 0.35 mg/l produced the reduction of at least 5 log in populations of approximately 1 x 10(6) cells/ml of Escherichia coli, Vibrio cholerae, Salmonella typhi, Yersinia enterocolitica, Pseudomonas aeruginosa, Aeromonas hydrophila, Listeria monocytogenes and Staphylococcus aureus. With a dose of 0.50 mg/l of chlorine, the reduction was much smaller for the tested microorganisms (except Vibrio cholerae), while the effect of 2 mg/l of chlorine was similar to the ozone treatment. For spores of Bacillus subtilis, the reduction observed with ozone concentrations of 0.35 and 0.70 mg/l was of almost 3 log, while no considerable effect was obtained with chlorine in the tested conditions. Our results have shown that both disinfectans were consumed during the treatment period, probably because of the own water demand and the added bacterial mass.