# Cavitary Pulmonary Disease Caused by Mycobacterium kyorinense : A Case Report on a 3‐Year Clinical Course

## TL;DR

An 80-year-old woman developed cavitary lung disease caused by Mycobacterium kyorinense, highlighting the need for early diagnosis to prevent severe lung damage.

## Contribution

Demonstrates the pathogenic potential of Mycobacterium kyorinense in causing cavitary pulmonary disease in a healthy individual.

## Key findings

- Mycobacterium kyorinense was identified as the causative agent of progressive cavitary pulmonary disease.
- Conventional diagnostic methods failed to identify the organism, requiring advanced techniques like MALDI-TOF MS.
- The case emphasizes the importance of early detection and treatment to prevent irreversible lung damage.

## Abstract

An 80‐year‐old female presented with haemoptysis, and chest computed tomography (CT) revealed bronchiectasis in the right middle lobe accompanied by granular and nodular opacities in the right lower lobe. Although acid‐fast bacilli (AFB) smears were consistently positive, polymerase chain reaction (PCR) assays for
Mycobacterium tuberculosis
yielded negative results, and repeated sputum cultures on conventional solid‐phase media failed to identify the causative organism. Cavitary pulmonary lesions developed progressively over 3 years, accompanied by persistent AFB smear positivity. Ultimately, liquid culture using the Mycobacteria Growth Indicator Tube (MGIT) system isolated nontuberculous mycobacteria, subsequently identified as
Mycobacterium kyorinense
(
M. kyorinense
) via matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOF MS). This case illustrates the pathogenic potential of
M. kyorinense
to induce cavitary pulmonary disease in otherwise healthy individuals, underscoring the necessity of early diagnostic strategies and prompt therapeutic intervention to prevent irreversible pulmonary damage.

This case illustrates the pathogenic potential of
M. kyorinense
to induce cavitary pulmonary disease in otherwise healthy individuals, underscoring the necessity of early diagnostic strategies and prompt therapeutic intervention to prevent irreversible pulmonary damage.