Survey of the acid-fast bacteria test trend in our hospital laboratory

Abstract

In this survey, we investigated the acid-fast bacteria test trend at our hospital laboratory and hereby report the findings. The medical facility of Yamanishi Medical Workers Association (Yamanishi MIN-IREN) managed the laboratory data of this hospital for 5 years, from October 2012 and September 2017. The status of acid-fast bacteria detection, age distribution, sex difference, comparison of various test items, rate of drug resistance, patients’ clinical background, and diagnosis as well as treatment of infection by nontuberculous mycobacteria (NTM) were also investigated. In the 5-year period, the positivity rate of the patients tested by acid-fast bacterial culture was 7.0%; among them, 35 (19.1%) patients had tuberculous bacteria, while 148 (80.9%) had NTM. With regard to age, most patients in both groups were aged ≥ 70 years, showing that most of them were elderly people. However, tuberculous bacteria were commonly observed in younger patients, aged 10–30 years. With regard to gender, tuberculous bacteria were predominantly observed in men, while NTM were predominantly observed in women. With regard to the test items, the positivity rate of the patients tested by acid-fast bacterial culture was high, that is, ≥ 90% of patients. In addition to common cold, asymptomatic abnormal X-ray findings were the common factors that prompted patients to visit the hospital for further examination. This survey can be used as a reference for the initial diagnosis and implementing appropriate interventions. Moreover, the status of acid-fast bacterial isolates varied regionally; therefore, the trend within a prefecture should be comprehensively understood for appropriate infection control measures.