Affiliation:
1. Department of Laboratory Medicine, State Key Laboratory of Complex, Severe, and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences , Beijing, China
2. Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases , Beijing, China
3. Department of Clinical Laboratory, Zhangjiajie People’s Hospital , Zhangjiajie, China
4. Department of Respiratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing, China
Abstract
ABSTRACT
Tsukamurella
species have been clinically regarded as rare but emerging opportunistic pathogens causing various infections in humans.
Tsukamurella
pneumonia has often been misdiagnosed as pulmonary tuberculosis due to its clinical presentation resembling tuberculosis-like syndromes.
Tsukamurella
species have also been confused in the laboratory with other phylogenetic bacteria, such as
Gordonia
. This study aimed to investigate the clinical, microbiological, and molecular characteristics; species distribution; and antimicrobial susceptibility of
Tsukamurella
species. Immunodeficiency and chronic pulmonary disease appeared to be risk factors for
Tsukamurella
pneumonia, and the presence of bronchiectasis and pulmonary nodules on imaging was highly correlated with this infection. The study confirmed that
groEL
(heat shock protein 60) and
secA
(the secretion ATPase) genes are reliable for identifying
Tsukamurella
species. Additionally, the
ssrA
(stable small RNA) gene showed promise as a tool for discriminating between different
Tsukamurella
species with the shortest sequence length. In terms of antimicrobial susceptibility, quinolones, trimethoprim/sulfamethoxazole, amikacin, minocycline, linezolid, and tigecycline demonstrated potent
in vitro
activity against
Tsukamurella
isolates in our study. The study also proposed a resistance mechanism involving a substitution (S91R) within the quinolone-resistance-determining region of the
gyrA
gene, which confers resistance to levofloxacin and ciprofloxacin. Furthermore, we found that disk diffusion testing is not suitable for testing the susceptibilities of
Tsukamurella
isolates to ciprofloxacin, imipenem, and minocycline. In conclusion, our systematic investigation may contribute to a better understanding of this rare pathogen.
Tsukamurella
species are rare but emerging human pathogens that share remarkable similarities with other mycolic acid–containing genera of the order Actinomycetales, especially
Mycobacterium tuberculosis
. Consequently, misdiagnosis and therapeutic failures can occur in clinical settings. Despite the significance of accurate identification, antimicrobial susceptibility, and understanding the resistance mechanism of this important genus, our knowledge in these areas remains fragmentary and incomplete. In this study, we aimed to address these gaps by investigating promising identification methods, the antimicrobial susceptibility patterns, and a novel quinolone resistance mechanism in
Tsukamurella
species, utilizing a collection of clinical isolates. The findings of our study will contribute to improve diagnosis and successful management of infections caused by
Tsukamurella
species, as well as establishing well-defined performance and interpretive criteria for antimicrobial susceptibility testing.
Funder
Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences
National High Level Hospital Clinical Research Funding
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Cell Biology,Microbiology (medical),Genetics,General Immunology and Microbiology,Ecology,Physiology