Microorganisms isolated at admission and treatment outcome in sputum smear-positive pulmonary tuberculosis

Cured or completed cases in newly diagnosed sputum smear-positive pulmonary tuberculosis (TB) is 47.7% in Japan in 2016. Aging of TB patients and their underlying conditions could affect treatment outcome. We analyzed the association between the isolation of microorganisms from sputum at admission and the 180-day mortality rate of the sputum smear-positive pulmonary TB patients in Chiba-East Hospital in Japan. Total subjects were 761 (median age: 63 years). Sputum test for microorganisms was conducted in 708 patients. Microorganisms other than the normal oral flora were isolated in 128 cases (18.1%). Details of the isolated microorganisms were as follows: methicillin-resistant Staphylococcus aureus 23 cases, Klebsiella pneumoniae 17 cases, Pseudomonas aeruginosa 16 cases. Mortality was significantly elevated in the patients with those microorganisms than the others (39.8% vs. 10.2%) (P < 0.01). Fifty-one of 128 patients with those microorganisms died, and 10 of them died of infectious disease, which is the most frequent cause of deaths. The factors associated with the isolation of those microorganisms were as follows: respiratory failure (adjusted odds ratio (aOR):2.5 95% confidence interval (CI) 1.3–4.7]), performance status 3 or 4 (aOR:2.9 95% CI 1.6–5.4]), serum albumin <3.0 mg/dL (aOR:2.1 95% CI 1.3–3.6], age of 65 years or older (aOR:2.0 95% CI 1.2–3.4]). Those strains were isolated from one of sixth patients. Patients with those microorganisms did not always develop infectious diseases; however, treatment outcomes were poor, with higher mortality. The isolations of microorganisms were associated with various underlying conditions, leading to death. Thus, attention should be paid to TB patients with the above factors.