Systematic investigation of the emerging pathogen of Tsukamurella species in a Chinese tertiary teaching hospital

species have been clinically regarded as rare but emerging opportunistic pathogens causing various infections in humans. pneumonia has often been misdiagnosed as pulmonary tuberculosis due to its clinical presentation resembling tuberculosis-like syndromes. species have also been confused in the laboratory with other phylogenetic bacteria, such as . This study aimed to investigate the clinical, microbiological, and molecular characteristics; species distribution; and antimicrobial susceptibility of species. Immunodeficiency and chronic pulmonary disease appeared to be risk factors for pneumonia, and the presence of bronchiectasis and pulmonary nodules on imaging was highly correlated with this infection. The study confirmed that (heat shock protein 60) and (the secretion ATPase) genes are reliable for identifying species. Additionally, the (stable small RNA) gene showed promise as a tool for discriminating between different species with the shortest sequence length. In terms of antimicrobial susceptibility, quinolones, trimethoprim/sulfamethoxazole, amikacin, minocycline, linezolid, and tigecycline demonstrated potent activity against isolates in our study. The study also proposed a resistance mechanism involving a substitution (S91R) within the quinolone-resistance-determining region of the gene, which confers resistance to levofloxacin and ciprofloxacin. Furthermore, we found that disk diffusion testing is not suitable for testing the susceptibilities of isolates to ciprofloxacin, imipenem, and minocycline. In conclusion, our systematic investigation may contribute to a better understanding of this rare pathogen. species are rare but emerging human pathogens that share remarkable similarities with other mycolic acid-containing genera of the order Actinomycetales, especially . 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 species, utilizing a collection of clinical isolates. The findings of our study will contribute to improve diagnosis and successful management of infections caused by species, as well as establishing well-