Time-to-positivity, type of culture media and oxidase test performed on positive blood culture vials to predict Pseudomonas aeruginosa in patients with Gram-negative bacilli bacteraemia / Tiempo de positividad, tipo de medio de cultivo y prueba de oxidasa realizada en viales de hemocultivo positivos para predecir Pseudomonas aeruginosa en pacientes con bacteriemia por bacilos gramnegativos

Introduction. The aim of this study was to determine the usefulness of oxidase test and time-to-positivity (TTP) in aerobic and anaerobic blood culture vials to detect the presence of Pseudomonas aeruginosa in patients with Gram-negative bacilli (GNB) bacteraemia. Material and methods. TTP was recorded for each aerobic and anaerobic blood culture vial of monomicrobial bacteraemia due to GNB. Oxidase test was performed in a pellet of the centrifuged content of the positive blood culture. An algorithm was developed in order to perform the oxidase test efficiently taking into account TTP and type of vial. Results. A total of 341 episodes of GNB bacteraemia were analysed. Sensitivity, specificity, positive predictive value and negative predictive value of the oxidase test performed on positive vials with GNB to predict P. aeruginosa were 95%, 99%, 91%, and 99%, respectively. When growth was first or exclusively detected in anaerobic vials, P. aeruginosa was never identified hence the performance of the oxidase test could be avoided. When growth was only or first detected in aerobic vials, a TTP≥8h predicted P. aeruginosa in 37% or cases (63 of 169), therefore oxidase test is highly recommended. Conclusions. Oxidase test performed onto positive blood culture vials previously selected by TTP and type of vials is an easy and inexpensive way to predict P. aeruginosa. In most cases, this can lead to optimization of treatment in less than 24 hours (AU)

Introducción. El objetivo del estudio fue determinar la utilidad de la prueba de oxidasa y del tiempo de positividad del hemocultivo (TPH) para detectar la presencia de Pseudomonas aeruginosa en pacientes con bacteriemia por bacilos gramnegativos (BGN). Material y métodos. Se registró el TPH de cada vial aerobio y anaerobio en todos los episodios de bacteriemia monomicrobiana por BGN. La prueba de oxidasa se realizó sobre el contenido centrifugado del hemocultivo positivo. Se diseñó un algoritmo para optimizar la realización de la prueba de oxidasa según el TPH y el tipo de vial. Resultados. Se analizaron 341 episodios de bacteriemia por BGN. La sensibilidad, especificidad, valor predictivo positivo y valor predictivo negativo de la prueba de oxidasa para predecir P. aeruginosa fueron del 95%, 99%, 91% y 99%, respectivamente. Cuando el crecimiento se detectó primero o exclusivamente en viales anaerobios, nunca se identificó P. aeruginosa pudiendo evitar la realización de la prueba de oxidasa. Cuando el crecimiento se detectó antes o exclusivamente en viales aerobios un TPH ≥8h predijo la presencia de P. aeruginosa en el 37% de los casos (63 de 169), por lo que es recomendable la realización de la prueba de oxidasa. Conclusiones. La prueba de oxidasa realizada a viales de hemocultivos positivos previamente seleccionados por el TPH y el tipo de medio es una forma fácil y económica de predecir P. aeruginosa. En la mayoría de los casos, esto puede contribuir a la optimización del tratamiento antibiótico en menos de 24h (AU)

Prevalence of hepatitis C virus infection in alcoholic patients: cohort study and systematic review.

AIMS: Prevalence of chronic hepatitis C virus (HCV) infection among alcoholics is thought to be higher than in the general population, although prevalence rates reported are quite variable. Our study is aimed to analyze HCV prevalence in a cohort of alcoholics and to perform a systematic review on this topic. PATIENTS AND METHODS: A total of 396 alcoholic patients consecutively referred to our Alcoholism Unit were included. HCV infection status and other clinical variables were recorded for each patient. Variables associated with HCV infection were analyzed by means of logistic regression. Additionally, we performed a systematic review focused on previous studies on this topic. RESULTS: Among our alcoholic patients, 14 of them (3.53%) had chronic HCV infection. Variables independently associated with HCV infection were female gender, injection drug use (IDU) and the presence of alcoholic liver disease (ALD). Twenty-four studies analyzing HCV prevalence in alcoholic patients were included in our systematic review, showing prevalence rates of HCV infection ranging from 2.1 to 51% and an average weighted prevalence of 16.32%. CONCLUSION: In our series, the prevalence rate of chronic HCV infection among alcoholic patients is lower than previously reported, which is probably explained by the relatively low number of patients with ALD or IDU in our sample. Prevalence rates previously published are quite different and the presence of ALD and/or IDU can act as confounding factors for HCV prevalence among alcoholics.