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

Comparison of different methods in order to identify Proteus spp. 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 Clinicas. 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.

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.

[Analysis of a Yersinia enterocolitica isolated from human diarrheic feces in Argentina]. / Análisis de una cepa de Yersinia enterocolitica aislada de heces diarreicas humanas en Argentina.

Some serotypes of Yersinia enterocolitica might cause diarrheas 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 determination as well as the search of the genes vir F and ail, were negatives. However, it was demonstrated enterotoxin production at 20 degrees C, and at 37 degrees 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 through other mechanisms of virulence, that would differ from those previously characterized in species of enteropathogenic Yersinia.

Análisis de una cepa de Yersinia enterocolitica aislada de heces diarreicas humanas en Argentina. / [Analysis of a Yersinia enterocolitica isolated from human diarrheic feces in Argentina]

Some serotypes of Yersinia enterocolitica might cause diarrheas 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 determination as well as the search of the genes vir F and ail, were negatives. However, it was demonstrated enterotoxin production at 20 degrees C, and at 37 degrees 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 ([quot ]avirulent[quot ]), could be the etiological agent of the illness through other mechanisms of virulence, that would differ from those previously characterized in species of enteropathogenic Yersinia.

[Characterization and distribution of Citrobacter species in a university hospital]. / Caracterización y distribución de especies de Citrobacter en un hospital universitario.

OBJECTIVE: [corrected] a) To identify Citrobacter strains following the conventional biochemical reaction of Brenner and col; b) to evaluate the sensitivity and specificity of the O'Hara's method compared with Brenner's method, and c) to determine the rate and distribution of the strains in the clinical isolates. MATERIAL AND METHODS: One hundred and twenty two clinical isolates, characterized as Citrobacter spp. were collected between May of 1994 and August of 1997. Clinical isolates included inpatients and outpatients from Hospital de Clínicas. Strains were identified following the methods of Brenner and O'Hara. RESULTS: Methods of Brenner identified 111 of 122 strains: C. freundii 59 of 111; C. koseri 18 of 111; C. werkmanii 15 of 111; C. braakii 9 of 111; C. youngae 6 of 111 and C. amalonaticus 4 of 111. O'Hara's methods identified 104 of 111 strains (94%). C. freundii was recovered most frequently from urine and feces (p Fisher < 0.026 and 0.039 respectively), while C. koseri was isolated from urine principally (p Fisher < 0.0372). CONCLUSIONS: The genus Citrobacter is an important opportunistic pathogen that can be identified in clinical microbiology laboratories using O'Hara's method.

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

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.

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.

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.

Antimicrobial effect of chlorine on Yersinia enterocolitica.

The effects of chlorine at varying pH, culture media and incubation temperatures on one type and two wild type strains of Yersinia enterocolitica were studied. Exposure to 1 and 5 mg 1(-1) did not diminish viability, even after prolonged exposure. A level of 10 mg 1(-1) was required to achieve a 5-log reduction in 120 s for the type strain and 80 s for the wild strains. There was an increase of more than 30% in the rate of disinfection with a 10 degrees C rise, a remarkable increase in antimicrobial activity at pH 5-log reduction in 20 s, as well as marked neutralization of the effect in the presence of 0.1% peptone. Younger cells were more susceptible than older ones, and those from liquid medium more resistant than those from solid medium. Incubation temperature of a 24-h inoculum failed to show any influence. Lastly, there was a noteworthy demand for free chlorine by bacterial biomass, with agreement of the curve depicting the drop in free chlorine in the presence of inoculum with biphasic kinetics of survival curves.

[Comparative study of microbial methods for the detection of genetic toxicity]. / Estudio comparativo de métodos microbianos para la detección de tóxicos genéticos.

It is important to have a rapid and accurate method to detect the toxic action of drugs and chemical compounds used by man. A comparative study with two microbial systems was carried out: one using Salmonella typhimurium and the other using Bacillus subtilis. The 1-8-dihydroxyantraquinone was the tested drug and the N-methyl-N'-nitro-N-nitrosoguanidine and the 2-aminofluorene were used as control substances. These compounds were used as such or after previous transformation by a microsomal system. The results obtained showed that both systems: the S. typhimurium and the B. subtilis work in a similar way, but the latter allows a more direct action of drug on the genetic material. The effect of the solvents: ethanol and dimethylsulfoxide was analysed, because they affected the transformation and reversion processes that were carried out.

Estudio comparativo de métodos microbianos para la detección de tóxicos genéticos / [Comparative study of microbial methods for the detection of genetic toxicity]

It is important to have a rapid and accurate method to detect the toxic action of drugs and chemical compounds used by man. A comparative study with two microbial systems was carried out: one using Salmonella typhimurium and the other using Bacillus subtilis. The 1-8-dihydroxyantraquinone was the tested drug and the N-methyl-N’-nitro-N-nitrosoguanidine and the 2-aminofluorene were used as control substances. These compounds were used as such or after previous transformation by a microsomal system. The results obtained showed that both systems: the S. typhimurium and the B. subtilis work in a similar way, but the latter allows a more direct action of drug on the genetic material. The effect of the solvents: ethanol and dimethylsulfoxide was analysed, because they affected the transformation and reversion processes that were carried out.

Estudio comparativo de métodos microbianos para la detección de tóxicos genéticos. / [Comparative study of microbial methods for the detection of genetic toxicity]

It is important to have a rapid and accurate method to detect the toxic action of drugs and chemical compounds used by man. A comparative study with two microbial systems was carried out: one using Salmonella typhimurium and the other using Bacillus subtilis. The 1-8-dihydroxyantraquinone was the tested drug and the N-methyl-N-nitro-N-nitrosoguanidine and the 2-aminofluorene were used as control substances. These compounds were used as such or after previous transformation by a microsomal system. The results obtained showed that both systems: the S. typhimurium and the B. subtilis work in a similar way, but the latter allows a more direct action of drug on the genetic material. The effect of the solvents: ethanol and dimethylsulfoxide was analysed, because they affected the transformation and reversion processes that were carried out.

[Food additives and their possible genetic toxicity; microbiological determination]. / Los aditivos alimentarios como posibles tóxicos genéticos deteriminación microbiológica.

In the present work we intend to find an accurat methodology to establish in an easy way the mutagenic potential of drugs employed as food additives. For that purpose we first selected a microbiological system for performing this assay. The method assayed consisted of investigating the effect exerted on genetic recombination by the following chemical agents: Chloroacetic Acid, Iodoacetic Acid, Sorbic Acid, Potassium Metabisulfite, Sodium Nitrite, Auramine and Erythrossine. The activity of these agents was detected though their effect on the transformation of an auxotrophic strain of Bacillus subtilis. Comparative assays of reversion of characters have been made with strains of Salmonella typimurium already used by other authors. These assays have also been repeated with several auxotrophic strains of Bacillus subtilis and different genetic characters have been studied. Most results suggest that changes in the recombination process should have occured at different levels according with the drugs assayed. On the other hand, the results of reversion have not been significant enough. We think that more accuracy is afforded by both the recombination and the reversion assay developed to other for this kind of detection.