Delayed diagnosis of tuberculosis in the medical intensive care unit

Purpose: With the resurgence of Mycobacterium tuberculosis (TB), prompt isolation and diagnosis have been priorities. We evaluated patients admitted to a medical intensive care unit (MICU) who were diagnosed with TB. Methods: Retrospective chart review of patients admitted to the MICU in whom TB was diagnosed during the 4 year period January 1994 through December 1997. Results: 26 patients (14% of 184 patients hospitalized with TB) required ICU admission. Admission diagnoses included pneumonia (42%), TB (19%), unusual diagnoses (e.g. hip fracture, neuroleptic malignant syndrome, out-of-hospital cardiac arrest, 50%). 65% of patients were immunocompromised, including 10 (38%) patients with HIV infection. The chest radiograph (CXR) showed a primary, postprimary, or miliary pattern consistent with TB in 10 (38%) patients. Respiratory isolation was initiated in 3 (12%) patients on admission. The mean time until respiratory isolation, TB diagnosis, or death (without isolation) was 10 days (range 1-35 days). AFB smears were positive in 12 (46%). Of the 10 patients with HIV infection, 4 patients had CXR suggestive of TB. Of the 6 patients with CXR not suggestive of TB, 5 had respiratory specimens positive for TB. Twenty-five (96%) patients required mechanical ventilation. The mean APACHE II score was 25. Duration of mechanical ventilation was 15 days, MICU stay was 20 days, hospital stay 39 days. Mortality was 62%. Conclusions: TB was unsuspected on admission in the majority of patients with TB in the MICU. Presenting diagnoses were unusual and chest radiographs were atypical. Pulmonary involvement was most common and requirement for mechanical ventilation was almost universal. Clinical Implications: The unusual presenting diagnoses, atypical chest radiographs, and the presence of multiorgan dysfunction may contribute to the lack of suspicion of TB in critically ill patients. In addition to the delay in treatment for the patient, mechanical ventilation and the delay in isolation raise the concern of nosocomial spread of TB.