Pneumonia in Immunocompromised and Immunocompetent Patients Requiring Mechanical Ventilation

Abstract

The role of bronchoscopic sampling including bronchoalveolar lavage (BAL) was assessed in patients with clinical symptoms consistent with pneumonia requiring mechanical ventilation. A total of 173 lavages were performed, with 144 patients on prior antibiotic regimens and 53 patients having human immunodeficiency virus (HIV) infection. The overall diagnostic yield was 34% (59 positive samples) with bacterial infection identified in 28 cases, Pneumocystis carinii in 24 cases, cytomegalovirus in 10 cases, fungal infection in 5 cases, and Mycobacterium tuberculosis in 2 cases. Seven patients had more than one pathogen identified. The diagnostic yield was higher in HIV-infected patients than other groups (chi-square = 17.21, P < .001). Prior antibiotics appeared to have no effect on the diagnostic yield. There was no difference in the type or sensitivity patterns of bacteria isolated from immunocompromised (19) versus immunocompetent (9) patients. We compared the bacterial sensitivities versus the American Thoracic Society recommendations for severe nosocomial pneumonia and found that up to one third of bacteria would have been resistant to the proposed treatments. The most common organisms causing failure were Staphylococcus aureus and Le-gionella (making up 7 of the bacterial isolates). The use of BAL allowed for an accurate diagnosis of pneumonia in more than one third of patients with ventilator-associated pneumonia despite widespread use of antibiotics.