CLINICAL AND EPIDEMIOLOGIC FINDINGS IN MECHANICALLY-VENTILATED PATIENTS WITH METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS PNEUMONIA

Over the 5-year period from 1990 to 1994, a prospective cohort study w as conducted to define the clinical and epidemiological characteristic s of ventilator-associated methicillin-resistant Staphylococcus aureus (MRSA) pneumonia acquired during a large-scale outbreak of MRSA infec tion. Of 2411 mechanically ventilated patients, 347 (14.4%) acquired M RSA, 220 (63.4%) had MRSA positive respiratory tract samples and 41 (1 8.6%) developed ventilator-associated MRSA pneumonia, The overall atta ck rate for ventilator-associated MRSA pneumonia was 1.56 episodes/100 0 ventilator days, but annual attack rates varied according to the tre nd of the outbreak (range 4.9-0.2). In comparison with methicillin-sen sitive Straphylococcus aureus (MSSA), which was implicated in 98 episo des of ventilator-associated pneumonia, MRSA caused exclusively late-o nset ventilator-associated pneumonia while MSSA caused both early-onse t [55 of 98 (56.1%) episodes] and late-onset [43 of 98 (43.8%) episode s] ventilator-associated pneumonia, Logistic regression analysis of al l patients with Straphylococcus aureus pneumonia revealed intubation f or more than 3 days (odds ratio (OR),1.11; confidence interval (CI):1. 03-1.18) and prior bronchoscopy (OR,5.8; CI,1.85-18.19) to be independ ent variables associated with MRSA pneumonia. The results indicate tha t MRSA ventilator-associated pneumonia is a frequent complication in i ntensive care patients, manifesting itself as late-onset pneumonia in patients who have been intubated for prolonged periods and/or have oft en undergoing previous bronchoscopy.