Análisis clínico-epidemiológico de la portación intestinal de enterococos resistentes a vancomicina en una unidad de terapia intensiva / Clinical and epidemiologic analysis of intestinal tract colonization with vancomycin-resistant enterococci in an intensive care unit

En un período de cinco meses y 25 días se investigó la portación intestinal de enterococos resistentes a vancomicina (EVR). Se estudiaron 124 pacientes (73%) de 171 admitidos en la unidad de terapia intensiva (UTI), 35 de los cuales (28%) resultaron ser portadores. Los aislamientos de EVR (n=35) fueron identificados como Enterococcus faecium (n=18), Enterococcus gallinarum (n=16) y Enterococcus raffinosus (n=1). Todos los aislamientos estudiados fueron resistentes a vancomicina (VAN) (CIM90= 512 µg/ml) y teicoplanina (CIM90= 32 µg/ml) y portaban el gen vanA. Los estudios de tipificación molecular mostraron un alto grado de homología entre los aislamientos de E. faecium (un clon dominante) y E. gallinarum (dos tipos clonales), sugiriendo su diseminación a modo de brote. No se encontraron diferencias significativas con la edad y el sexo de los pacientes no portadores (p>0,05), pero si con el tiempo de hospitalización y el uso de esquemas antibióticos de amplio espectro (p<0,05), estando estos dos factores asociados al estado de portación. Se deduce de este estudio, la importancia de maximizar las medidas de prevención y control de las infecciones nosocomiales, analizar los esquemas empíricos empleados, tratar de disminuir el tiempo de hospitalización y continuar con los estudios de vigilancia para evaluar la eficacia de las acciones implementadas.

Intestinal tract colonization with vancomycin resistant enterococci (VRE) was studied during five months and 25 days. Out of 171 patients hospitalized in the intensive care unit, 124 (73%) were included in this study. Thirty five of them (28%) were recognized as colonized with VRE. VRE isolates (n = 35) were identified as Enterococcus faecium (n=18), Enterococcus gallinarum (n=16), and Enterococcus raffinosus (n=1). All of them were resistant to vancomycin (MIC90= 512 µg/ml) and to teicoplanin (MIC90= 32 µg/ml), having the vanA gene. By means of molecular methods a high homology was found among E. faecium and E. gallinarum isolates, respectively, suggesting their spread as a kind of outbreak. No significant differences in age or sex were found among colonized and non-colonized patients (p>0.05). On the other hand, the hospitalization time and the use of broad-spectrum antibiotics were associated with colonization. From this study we highlight the importance of enhancing all measures of control and prevention of hospital infections, carefully analyzing the empiric antimicrobial schemes, trying to reduce the hospital stage, and following the surveillance to evaluate the efficacy of such procedures.

Análisis del sistema MGIT (Mycobacteria Growth Indicator Tube) en el aislamiento primario de micobacterias / Analysis of the MGTI (Mycobacteria Growth Indicator Tube) system in the primary isolation of mycobacteria

The advantages of Mycobacteria Growth Indicator Tube (MGIT) system were analyzed and compared to L÷wenstein-Jensen (LJ) and Stonebrink (S) solid media when searching for a fast method to diagnose tuberculosis and mycobacterioses, which should be easy to perform in laboratories and of non-invasive reading. All nonsterile specimens were pretreated with Petroff method. A total of 191 specimens were processed (among which 152 were pulmonary and 39 extrapulmonary). Twenty-nine tested positive by one of the methods employed. The rate of recovery of smear positive specimens (ED+) was of 92 with LJ/S, and 85 with MGIT. The mean time to detect a positive result was 18.7 days with MGIT, and 20.6 days with LJ/S. The rate of recovery of smear negative specimens (ED-) was 88.2 with LJ, 70.6 with S, and 23.5 with MGIT. The mean time to detect a positive result were 38.5; 26.5 and 29 days, respectively. During this experiment, MGIT did not seem to have any advantage over the traditional methods, particularly when working with samples containing a low number of bacilli (p < 0.05). It is obviously necessary to make a comparative study with a large amount of cases which might support this observation and to analyze the influence of the reagents employed in the pre-treatment of the specimens on the MGIT system's efficacy to detect mycobacteria.