[Trends in the prevalence of extended-spectrum beta-lactamase-producing gram-negative bacilli in a teaching hospital in Madrid, Spain].

BACKGROUND AND OBJECTIVE: The pprevalence of extended-spectrum beta-lactamase (ESBL) producing gram-negative bacilli has increased in recent years. The aim of this study is to estimate the prevalence of infection/colonization due to theses microorganisms per 100 admissions and its trend during the period 2007-2010.

PATIENTS AND METHODS: Prospective observational study of all patients admitted from January 2007 to December 2010 infected or colonized with ESBL-producing gram-negative bacilli at Hospital Universitario Ramón y Cajal. The prevalence of infection/colonization of ESBL-producing gram-negative rods was calculated according to the recommendations for metrics for multidrug-resistant organisms in healthcare settings of The Society for Healthcare Epidemiology of America and the Healthcare Infection Control Practices Advisory Committee. To analyse trends, Poisson regression was used (Joinpoint Regression Program Version 3.4.3, U.S. National Institutes of Health).

RESULTS: Through the study period there was an upward trend of prevalence of all the ESBL-producing gram-negative bacilli. The Poisson trend analysis indentified a significant inflection point in August 2009 (p=0.014).

CONCLUSION: The inflection point in the prevalence of the ESBL-producing gram-negative bacilli trend can be explained by a slowdown in the prevalence of some microorganisms such as ESBL-producing Klebsiella pneumoniae.