Jianhua Fang,1,2,* Qiong Liu,3,* Huade Chen,1,2,* Hongyi Lai,4 Jingyi Huang,5,6 Jiayue Li,5,6 Yilin Xu,7 Na Cheng,1,2,7 Tianxin Xiang1,8,9 

1Jiangxi Provincial Key Laboratory of Prevention and Treatment of Infectious Diseases, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi, 330052, People’s Republic of China; 2Infectious Disease Department, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi, 330052, People’s Republic of China; 3Nanchang Medical College, Nanchang, 330006, People’s Republic of China; 4The First Clinical College, Jiangxi Medical College, Nanchang University, Nanchang, 330006, People’s Republic of China; 5Department of Pediatrics, Nanchang University, Nanchang, 330006, People’s Republic of China; 6Department of Pediatrics, The First Affiliated Hospital of Nanchang University, Nanchang, 330031, People’s Republic of China; 7Infection Control Department, The First Affiliated Hospital of Nanchang University, Nanchang, 330031, People’s Republic of China; 8Jiangxi Medical Center for Critical Public Health Events, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi, 330052, People’s Republic of China; 9Jiangxi Hospital of China-Japan Friendship Hospital, Nanchang, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Tianxin Xiang, Email txxiangmed@163.com Na Cheng, Email chengnah@sina.com

Introduction: Klebsiella pneumoniae (KP) is a common Gram-negative bacterium in clinical practice and can cause various infectious diseases, including pneumonia, liver abscess and bloodstream infection. Carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a major threat to global health due to its high incidence and mortality rates, especially the ST11-CRKP strain prevalent in China.
Methods: The age, main clinical diagnosis, previous health and immune status of the two patients with ST11-CRKP-related infections during the same period reported in this study were similar.
Results: The antibiotic treatment regimens for the two patients were the same in terms of the type and dosage of antibiotics, except for omadacycline. Meanwhile, PFGE, multilocus sequence typing (MLST), and K typing confirmed that the two strains had the same genetic background. Through experiments on serum resistance, biofilm formation, the Galleria mellonella infection model and the hypermucus phenotype, it was found that CRKP1 showed a hypervirulent phenotype, while CRKP15 showed a hopervirulent phenotype. Whole-genome sequencing further revealed the differences in virulence genes between the two strains and further confirmed the virulence phenotypes of the two strains. Single nucleotide polymorphism (SNP) analysis showed that the terw gene was one of the key genes for the virulence difference of the two strains with the same genetic background under the therapeutic difference of omadacycline. In addition, the effect of omadacycline on the expression of the terw gene was evaluated by qRT-PCR technology. The interaction between the terw gene and omadacycline was confirmed through molecular docking.
Conclusion: To sum up, these findings suggest that under the therapeutic stress of omadacycline, CRKP may adjust virulence through adaptive evolution, and the terw gene may be the key factor for the differences in virulence within this bacterial population.

Keywords: Klebsiella pneumoniae, CRKP, omadacycline, terw, virulence