Detección de virus Norwalk y México, dos calicivirus humanos en deposiciones de niños chilenos / Detection of Norwalk and Mexico virus, 2 human calciviruses in feces of chilean children

Background: Human calciviruses (HuCVs) cause diarrhea outbreaks associated with consumption of contaminated food and water. Seroepidemiological studies in developing countries, suggest that HuCVs can cause acute gastroenteritis in children. Aim: To study the presence of Norwalk (NV) and Mexico (MX) virus, two HuCVs, in stools of Chilean children from different settings. Subjects and methods: ELISA tests for NV and MX were performed in 677 stool samples for children aged 0 to 132 years old, with acute diarrhea occurring in day care centers or consulting in outpatient clinics or emergency rooms. We also studied eight samples from children involved in a diarrhea outbreak that occurred in a rural community in 1992. A subset of samples was tested with polymerase chain reactions using different primers. Results: Only one sample from a child with acute diarrhea occurring in a day care center was positive for HuCV by polymerase chain reaction. Three samples from the outbreak were positive by the latter method and by ELISA. The HuCV obtained from the day care center was genetically different from other known HuCV. Conclusions: Despite the high seroprevalence, NV and MX viruses were detected in a very low proportion of Chilean children stools

Estudio molecular de 6 episodios de infección intrahospitalaria causados por staphylococcus aureus meticilino-resistente / Molecular study of 6 episodes of intrahospitalary infection due to methicillin resistant staphylococcus aureus

A critical step in any epidemiologic research concerning nosocomial infections is the precise identification of the responsible pathogen. The present work utilized a molecular approach-plasmids identification, restriction lengght polymorphism DNA analysis and random amplified polymorphic DNA for the characterization of 6 nosocomial outbreaks due to 52 strains of methicillin-resistant staphylococcus aureus (MRSA). In these episodes, the clinic-epidemiologic and phenotipic analysis (antibiotype) pointed to a nosocomial infection. Through molecular analysis it was possible to establish in a very precise way, clonality due to MRSA strains in 2 of the studied outbreaks; the same type of analysis allowed to eliminate a MRSA clonal origin in the remainder 4 episodes. The antibiogram was not an useful analytic tool due to its poor discriminatory power. Also, through a PCR procedure, it was possible to identify the presence of the gen mecA in every of the 52 MRSA strains studied