[Identification of risk times for dissemination of methicillin-resistant Staphylococcus aureus in an intensive care unit]. / Identificación de los tiempos de riesgo de diseminación de Staphylococcus aureus resistente a meticilina en una unidad de medicina intensiva.

BACKGROUND AND OBJECTIVE: The dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to an Intensive Care Unit (ICU) depends, among other reasons, on the time interval between obtention of the first positive sample and the establishment of measures for contact isolation. The objective of this study was to identify the risk intervals for the spread of MRSA in ICU patients and to assess the relationship between these periods and the development of new cases of MRSA acquired in the ICU. MATERIAL AND METHOD: Observational and prospective study, which was carried out in a 18-bed polyvalent ICU during a 49-month period (October 1998-October 2002). The exposure risk period was defined as the time elapsed between obtention of the first positive sample and contact isolation of the index case, and the window period as the time elapsed between recovery of the last negative sample to the first positive sample. Infection sources of MRSA were classified into community-acquired and hospital-acquired (nosocomial extra-ICU and nosocomial intra-ICU infections). RESULTS: MRSA was isolated in 69 (2.73%) of 2,531 patients admitted to the ICU during the study period and in all patients measures of contact isolation were indicated. Community-acquired MRSA was diagnosed in 9 (13%) cases, nosocomial intra-ICU in 29 (42%), and nosocomial extra-ICU in 31 (44.9%). The mean duration of the exposure risk period was 3.1 (SD 2.2) (median 3, range 0-9) days and the window period 2.9 (SD 4.6) (median 1, range 0-28) days. In 18 of the 29 cases of intra-ICU-acquired MRSA (62.1%; 95% CI, 42.3-79.3), the infection was acquired within the exposure risk and/or window periods of other patients with MRSA. CONCLUSIONS: The exposure risk periods and the window periods showed a strong relationship between detection of new cases of intra-ICU colonization and/or infection by MRSA.

[Effectiveness of contact isolation in the control of multiresistant bacteria in an intensive care service]. / Efectividad del aislamiento de contacto en el control de bacterias multirresistentes en un servicio de medicina intensiva.

AIM: To describe the frequency, characteristics and progression of critically ill patients admitted to the ICU, for whom isolation is indicated due to detection of multiresistant pathogenic bacteria, and to study the effectiveness of precautionary measures to avoid dissemination of these microorganisms. PATIENTS AND METHODS: Prospective, observational, cohort study performed by a specially created working group of four nurses and an ICU specialist. The study included 55 patients in whom contact isolation was indicated (isolation rate, 15.2 per 100 patients), collected over a 16-month period. RESULTS: The multiresistant bacteria responsible for isolation of the patients were: Pseudomonas aeruginosa (17 cases), Staphylococcus aureus (17 cases), Stenotrophomonas maltophilia (15 cases), Acinetobacter baumannii (4 cases) and extended-spectrum beta-lactamase (ESBL)- producing Enterobacteria (2 cases). Vancomycin-resistant Enterococcus spp. was not identified in any case. The mean duration of ICU isolation was 17.6 6 5.1 days (range 1-75). Multiresistant bacteria were classified as intra-ICU nosocomial in 39 cases (70.9%), extra-ICU nosocomial in 10 cases (18.2%) and community-acquired in 6 (10.9%). During the study period, no epidemic outbreak due to any of the controlled bacteria was detected. The multiresistant bacteria presented in the form of colonization in 41 cases (74.5%). The reasons for discontinuing isolation were death of the patient in 18 cases, transferal to a hospital ward (discharge from the ICU) in 19 cases, and eradication of the bacteria in 18 cases. Of the 55 patients with multiresistant bacteria, 35 (63.6%) died during hospitalization, and 23 of these (41.8%) during their stay in the ICU. CONCLUSIONS: The implementation of a working team for early detection of multiresistant pathogenic bacteria resulted in application of contact isolation in 15.2% of patients admitted. Surveillance to fulfill isolation precautions in a medical-surgical ICU achieved an absence of epidemic outbreaks due to these bacteria during the study period.

Efectividad del aislamiento de contacto en el control de bacterias multirresistentes en un servicio de medicina intensiva / Effectiveness of contact isolation in the control of multiresistant bacteria in an intensive care service

FUNDAMENTO. Describir la frecuencia, características y evolución de pacientes críticos, ingresados en UCI, con indicación de aislamiento de contacto por identificación de bacterias patógenas multirresistentes (BPMR) y demostrar la efectividad de las medidas aplicadas para evitar su diseminación. PACIENTES Y MÉTODO. Estudio de cohortes, prospectivo y observacional. Para realizar el estudio se formó un grupo de trabajo compuesto por 4 enfermeras y un médico de UCI. Se han incluido 55 pacientes en los que se indicó aislamiento de contacto (tasa de aislamiento 15,2 por 100 pacientes), durante un período de 16 meses. RESULTADOS. Las BPMR motivo de aislamiento han sido: Pseudomonas aeruginosa en 17 casos, Staphylococcus aureus en 17 casos, Stenotrophomonas maltophilia en 15 casos, Acinetobacter baumannii en 4 casos y enterobacterias productoras de betalactamasas de espectro ampliado (BLEAS) en 2 casos. En ninguna ocasión se han identificado Enterococcus spp. resistentes a vancomicina. La duración media de los aislamientos en UCI ha sido de 17,6 5,1 días (límites entre 1 y 75 días).Las BPMR fueron clasificadas como nosocomiales intra-UCI en 39 casos (70,9 por ciento), nosocomiales extra-UCI en 10 casos (18,2 por ciento) y comunitarias en 6 casos (10,9 por ciento). Durante el período de este estudio no se ha detectado ningún brote epidémico por alguna de las BPMR que se han controlado. Las BPMR se han presentado en forma de colonización en 41 casos (74,5 por ciento). El motivo de finalización del aislamiento fue por fallecimiento en 18 casos, por traslado a una unidad de hospitalización (alta de UCI) en 19 casos, y por erradicación de la BPMR en 18 casos. Durante su estancia en el hospital fallecieron 35 (63,6 por ciento) de los 55 pacientes con BPMR, de ellos, 23 (41,8 por ciento) durante su estancia en UCI.CONCLUSIONES. La puesta en funcionamiento de un equipo de trabajo para la detección precoz de BPMR ha supuesto la aplicación de medidas de aislamiento de contacto en el 15,2 por ciento de los pacientes ingresados. La vigilancia del cumplimiento de las medidas de aislamiento en una UCI medicoquirúrgica se ha acompañado de ausencia de brotes epidémicos por BPMR durante el período de estudio (AU)