Over 10 Years of Tuberculosis-Understanding the Manifestations, Epidemiology and Clinical Characteristics of Tuberculosis Cases at a United States Military Hospital.

INTRODUCTION: Tuberculosis (TB) causes significant morbidity and mortality worldwide. Diagnosing TB in service members can be a challenge given the overall low incidence but increased risk of exposure that accompanies military travel, training and activities. Here we describe clinical features, risk factors, and characteristics of initial diagnoses of TB at the largest Department of Defense hospital.

MATERIALS AND METHODS: Acid-fast bacilli cultures positive for Mycobacterium tuberculosis at Brooke Army Medical Center were reviewed identifying TB cases between 2010 and 2023. Epidemiologic, clinical, and microbiologic data were collected from medical records. Only patients with initial diagnosis at Brooke Army Medical Center (BAMC) were included.

RESULTS: Twenty-nine patients (65% non-U.S. born) were diagnosed with TB, primarily pulmonary. Latent tuberculosis infection was the most common comorbidity (33%), followed by diabetes and lung disease (21% and 17%). Cough and sputum production were the most frequent symptoms (59%, 48%); 24% were asymptomatic at diagnosis. Acid fast bacilli (AFB) smear positive patients were older with higher rates of classic TB symptoms. Median number of sputum cultures was 4; 58% were collected at least 8 hours apart; 41% had one collected before 10 AM. Only 75% of samples included TB nucleic acid amplification testing (NAAT).

CONCLUSIONS: Acid fast bacilli smear negative patients tended to be younger, asymptomatic, have more chronic lung disease, extrapulmonary disease, prior latent tuberculosis infection (LTBI), and longer time from symptoms to treatment highlighting the diagnostic difficulty of these cases. Patients with sputum negative disease and extrapulmonary TB had more days between symptom onset and treatment than AFB sputum positive TB cases. Half of AFB smear negative active duty patients were also TB NAAT negative. Care should be taken when evaluating young, asymptomatic active duty patients with high-risk histories and features for tuberculosis. More research is needed to enhance initial diagnostic evaluation and testing and evaluation for TB in civilian and military population.