[Methicillin-resistant Staphylococcus aureus at a general hospital: epidemiological overview between 2000-2007]. / Staphylococcus aureus resistente a meticilina en un hospital general: panorama epidemiológico del 2000 al 2007.

INTRODUCTION: The high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in hospitalized patients is a significant problem due to its associated morbidity and mortality. It is important to know the recent MRSA epidemiology at a General Hospital. OBJECTIVES: To determine the MRSA epidemiology at a Mexican general hospital from 2000 to 2007, in order to know if there is a significant trend in its proportion. MATERIAL AND METHODS: Prevalence survey. The resistance to oxacillin was identified by the Kirby-Bauer's method. The specimens were classified by type and year of isolation. Trend statistics were used for analysis. RESULTS: S. aureus was identified in 1,008 samples, being 301 resistant to oxacillin (30%, 95% Confidence Interval [CI], 25 to 35%). The proportion of MRSA went from 37% (95% CI, 29 to 44%) to 49% (95% CI, 40 to 58%) in the period of study (chi2 for trends = 6.676, p < 0.01). Specimens with the highest proportion of MRSA were blood and sterile liquids with 32% (95% CI, 26 to 39%), secretions with 29% (95% CI, 24 to 33%), and catheters with 21% (95% CI, 16 to 26%). CONCLUSIONS: The proportion of MRSA has increased significantly. This leads to higher costs and morbi-mortality for the hospitalized patients. We require stricter policies to prevent transmission and to control the use of antibiotics.

Inadequate therapy and antibiotic resistance. Risk factors for mortality in the intensive care unit.

BACKGROUND: The impact of nosocomial infections and multidrug resistance on mortality is a topic of considerable controversy. METHODS: A prospective, nested case control study was conducted in four intensive care units (ICUs) in Mexico to measure the impact of antibiotic resistance on and identify the main risk factors for mortality in critically ill patients with nosocomial infections. RESULTS: One hundred thirteen patients developed 119 nosocomial infections. Multivariate analysis identified two variables that were significantly and independently associated with mortality: ventilator-associated pneumonia (p = 0.0041, odds ratio [OR] = 7.7) and inadequate antibiotic treatment (p <0.0001, OR = 70.5). Although antibiotic resistance in Gram-negative rods was not an independent risk factor for mortality, there was a strong association between antibiotic resistance and inadequate treatment (chi2 for linear trend = 29.3, p <0.00001). For patients with ventilator-associated pneumonia, predicted mortality calculated by APACHE II score was 23% compared to an observed mortality of 71%. CONCLUSIONS: In this study the major risk factors for mortality were inadequate antibiotic treatment and development of ventilator-associated pneumonia. Multidrug resistance significantly increased the probability of receiving inadequate antibiotic treatment. The striking differences between observed and predicted mortality in these four ICUs indicate the need for further research and a reassessment of the current programs for prevention and control of nosocomial infections in Mexico.