Background: Mycobacterium kansasii is the second most common nontuberculous mycobacterial pulmonary disease pathogen in Japan. Fibrocavitary disease is characteristic of M. kansasii pulmonary disease in male patients.
Objective: To clarify the clinico-microbiological characteristics of M. kansasii pulmonary disease in recent years in a Tokyo hospital specializing in mycobacteriosis.
Methods: A retrospective chart review was performed on 77 M. kansasii culture-positive cases from January 2003 to December 2010. Sequence analysis of the hsp65 gene using PCR-restriction enzyme pattern analysis (hsp65-PRA) was used to identify bacterial genotypes.
Results: Seventy-four cases fulfilled the diagnostic criteria for inclusion. Female patients comprised 22% of cases (16 cases, 63.2 ± 24.6 years of age) and were older than male patients (58 cases, 55.5 ± 17.5 years of age). Although the peak distribution among men was patients in their 50s, female patients showed a bimodal distribution with increased occurrence in older women. Radiological examination showed that approximately 90% of male and younger female patients had fibrocavitary disease. However, elderly female patients tended to have nodular bronchiectatic disease. Genotype analysis revealed that all bacterial strains from both genders were subtype I.
Conclusions: Compared to previous reports, the number of female patients with M. kansasii pulmonary disease had increased, with an unusual age distribution. These different age-related radiological findings might be due to host factors.