Microbiological and serological control of Escherichia coli O157: H7 in kindergarten staff in Buenos Aires city and suburban areas

Shiga toxin (Stx)-producing Escherichia coli (STEC) infections are implicated in the development of the life-threatening hemolytic-uremic syndrome (HUS). Despite the magnitude of the social and economic problems caused by HUS, no licensed vaccine or effective therapy is currently available for human use. Prevention of STEC infections continues being the most important measure to reduce HUS incidence. This is especially true for Argentina where HUS incidence among children is extremely high and shows an endemic pattern. The aim of this work was to investigate serologically adult staff of kindergartens in Buenos Aires city and suburban areas in order to detect possible carriers, and to educate personnel about good practices to reduce HUS transmission. We also assessed the microbiological quality of water and meal samples from the same kindergartens. We tested 67 healthy adults, 13 water supplies and 6 meals belonging to 6 public kindergartens. We analysed hand swabs for isolation of STEC and serum samples for the presence of antibodies against Stx and lipopolysaccharide (LPS) of O157 serogroup. We identified 46 Stx2-positive individuals, but only 7 for O157 LPS. No presence of STEC pathogens was detected in hands of staff, water or meal samples.

Las infecciones bacterianas con Escherichia coli productor de toxina Shiga (Stx) (STEC) están implicadas en el desarrollo del síndrome urémico hemolítico (SUH). A pesar de la magnitud del problema social y económico causado por el SUH, actualmente no existe un tratamiento específico o una vacuna eficaz para uso humano. Por lo tanto, la prevención de las infecciones por STEC es la tarea central para reducir la incidencia del SUH. Esto es especialmente cierto para Argentina en donde el SUH muestra un comportamiento endémico y presenta una incidencia extremadamente alta entre los niños. En efecto, la mediana de casos notificados en menores de 5 años para el periodo 2010-2015 fue 306, mientras que la tasa de notificación fue 8.5 casos cada 100 000 menores/año (http://www.msal.gob.ar/images/stories/boletines/boletin_integrado_vigilancia_N335-SE45.pdf). El objetivo de este trabajo fue analizar serológicamente al personal adulto de jardines de infantes de la ciudad de Buenos Aires y el área suburbana con el fin de detectar portadores, y brindarles formación sobre las buenas prácticas para reducir la transmisión de infecciones con STEC y así evitar el SUH. También se evaluó la calidad microbiológica de las muestras de agua y de la comida elaborada en los mismos jardines. Hemos estudiado 67 adultos, a través del hisopado de manos para la búsqueda de STEC y suero para la presencia de anticuerpos contra Stx y el lipopolisacárido (LPS) de serogrupo O157. También se analizaron 13 suministros de agua y 6 muestras de comida pertenecientes a 6 jardines de infantes públicos. Se identificaron 46 individuos positivos para Stx2, pero solo 7 para LPS-O157. No se detectó presencia de patógenos STEC en las muestras de las manos del personal, ni en los reservorios de agua o muestras de comida.

Von Willebrand factor cleaving protease activity in the physiopathology of microangiopathic disorders

The von Willebrand factor cleaving protease (VWFCP) modulates the von Willebrand factor (VWF) multimeric size in normal plasma. VWFCP activity levels are decreased in different physiological and pathologic situations. Different techniques have been developed to unfold the purified VWF (perfusion at high shear rate, dialysis against urea in nitrocellulose filters), to detect the VWFCP activity on it (multimeric analysis of VWF, collagen binding to VWF assay) and to use the patient plasma both as the source of the enzyme and substrate. In this paper we compared the above mentioned methods with new ones: normal plasma dialyzed on membranes instead of purified VWF, dialysis of the samples against urea in tubing instead of nitrocellulose filters, and sonicated plasma to remove the endogenous VWF. The perfusion assay and detection by multimeric analysis showed a limit of detection (25%) of VWFCP activity. Dialysis against urea in both supports and detection by multimeric analysis, showed a better limit of detection (3%), but the recovery of the samples was not as efficient in nitrocellulose filters as it was in tubing. The detection by collagen binding to VWF has more advantages because it allows to analyze more samples than the multimeric analysis does in the same assay. The dialysis of plasma by membranes to obtain the source of exogenous VWF requires no complex equipment. The method, which uses patient plasma as the source of the enzyme and substrate, was inapplicable in our experience because the values could not be interpolated in the reference curve