Survival of Staphylococcus aureus on sampling swabs stored at different temperatures.

AIMS: To understand the impact of storage temperature on recovery of Staphylococcus aureus on sampling swabs. Staphylococcus aureus is a common cause of skin and soft tissue infections, but also causes a variety of life-threatening diseases. With a large pool of asymptomatic carriers and transmission that can occur even through indirect contact, mitigation efforts have had limited success. Swab sampling, followed by culturing, is a cornerstone of epidemiological studies, however, S. aureus viability on swabs stored at different temperatures has not been characterized. METHODS AND RESULTS: We determined survival rates on swabs stored at five different temperatures. Samples stored at -70°C had no decay over time while samples stored at higher temperatures showed an exponential decay in viability. Mortality rates were greatest for swabs stored at 37°C. Survival at intermediate temperatures (-20 to 20·5°C) did not differ significantly, however, we observed more variation at higher temperatures. CONCLUSIONS: To maximize recovery of S. aureus cells, samples should be stored at -70°C or processed for culturing without delay. SIGNIFICANCE AND IMPACT OF THE STUDY: Epidemiological studies of bacterial diseases are typically limited to determination of pathogen presence/absence, yet quantitative assessments of pathogen load and genetic diversity can provide insights into disease progression and severity, likelihood of transmission and adaptive evolutionary potential. For studies of S. aureus where time or access to a microbiology laboratory may delay culturing, deep freezing or timely culturing will maximize the degree to which sampling results reflect source status.

Resultados del programa de atencion Médico-Quirúrgica sin uso de sangre ni hemoderivados del Hospital Clínico de la Universidad de Chile / Results of program of medical and surgical attention without the use of blood and derivates in the University of Chile Clinical Hospital

Se presentan 128 pacientes quirúrgicos de un total de 161, que ingresaron al programa de atención sin uso de sangre ni hemoderivados entre enero de 1999 y octubre de 2002 en el Hospital Clínico de la Universidad de Chile. Siendo ésta la primer casuística en nuestro país en un programa de este tipo. Se clasifican en tres grupos (bajo, mediano y alto riesgo) según la posibilidad de ser transfundidos delineada a partir de la patología de base, Hto y Hb preoperatoria y riesgo de sangramiento quirúrgico. En principio los programas de atención médica quirúrgica sin uso de sangre, ni hemoderivados, fueron en respuesta a la negativa de transfundirse por parte del grupo religioso Testigos de Jehová. En su desarrollo se comprobó que los niveles de tolerancia a la anemia, están más allá de lo presupuestado, que el uso de la transfusión en muchos casos no estaba claro y en algunos sobredimensionados.