Molecular Epidemiological Characteristics of Hypervirulent Klebsiella pneumoniae in Yakeshi City, Hulunbuir, China.

Background: This study aimed to investigate the molecular epidemiological characteristics of hypervirulent Klebsiella pneumoniae (hvKp) in Yakeshi City, Hulunbuir, China, analyze the resistance of hvKp to commonly used antibiotics, explore independent risk factors for hvKp infection, and provide a research basis for anti-infection treatment.

Methods: In total, 519 strains of K. pneumoniae, identified by the Inner Mongolia Forestry General Hospital from January 2020 to December 2022, were collected, and high-viscosity (HMV-Kp) and non-HMV-Kp strains were differentiated using string test. PCR and agarose gel electrophoresis were used to detect the rmpA, rmpA2, and iutA genes to identify hvKp strains. Sixty strains of hvKp were randomly selected for capsular serotyping by PCR and agarose gel electrophoresis. Sanger sequencing was used to sequence the housekeeping genes of 60 hvKp strains and perform ST analysis. A minimum spanning tree was drawn using capsule serotyping and ST typing. Significant differences in resistance to commonly used antibiotics between classical K. pneumoniae (cKp) and hvKp were analyzed by using the chi-squared test. Finally, the risk factors for hvKp infection were analyzed through binary logistic regression.

Results: The HMV-Kp detection rate was 39.69%, versus 37.19% for hvKp. HMV-Kp accounted for 84.97% of all hvKp isolates. The hvKp detection rate was highest in the general surgery department. In capsule serotyping, K1 was the main subtype, accounting for 63.33% of all isolates (38/60), followed by K2 (16.67%, 10/60). Through ST typing, 18 subtypes were detected, with ST23 being the most common (50.00%), followed by ST86 (8.33%), and the remaining subtypes were scattered throughout the distribution. Compared with cKp, hvKp strains exhibited higher sensitivity to commonly used antibiotics, excluding furantoin. Male gender (odds ratio (OR) = 1.977), liver abscess (OR = 15.019), and the use of macrolide antibiotics in the past 3 months (OR = 5.473) were independent risk factors for hvKp infection.

Conclusions: The hvKp detection rate in the local area was 37.19%, and a strong correlation was noted between hvKp and HMV-Kp strains. K1-ST23 was the dominant subtype in this study. Compared with cKp, hvKp strains were more sensitive to commonly used antibiotics. Male gender, liver abscess, suppuration or infection of other tissues and organs, and recent macrolide antibiotic use were risk factors for hvKp infection.