Hidden burden of intestinal Klebsiella pneumoniae in Taiwan: insights into pathogenic potentials and genomic diversity

Abstract

BackgroundKlebsiella pneumoniae is a major human pathogen implicated in both nosocomial and community-acquired infections, such as pyogenic liver abscess (PLA). The emergence and global proliferation of hypervirulent and multidrug-resistant K. pneumoniae have positioned it as a significant clinical and public health threat. The intestine is one of the main reservoirs of K. pneumoniae in the human body, with varied gastrointestinal (GI) carriage rates reported across different geographical regions. Clinical studies have suggested that K. pneumoniae infections may be preceded by gastrointestinal colonization. However, the pathogenic potential of gastrointestinal strains in the general population remains unclear. This study aimed to determine the prevalence, genetic diversity, drug resistance profiles, and virulence potential of K. pneumoniae from the intestinal microflora in the community.ResultsTwo hundred and four intestinal strains of K. pneumoniae were isolated from 307 adults undergoing health check-ups at a hospital in Taiwan. The intestinal carriage rate of K. pneumoniae was 63.2%, higher in females (66.2%) than in males (50.8%). Phenotypic testing revealed that 20.1% of strains were hypermucoviscous, 30.4% serum-resistant, 18.1% phagocytosis-resistant, and 24.5% were high biofilm producers. Most strains (96.1%) exhibited intestinal cell adhesion equal to or greater than a highly adhesive clinical strain. Multidrug resistance was observed in 3.43% (7/204) of intestinal colonization strains. Whole-genome-sequencing (WGS) analysis of 204 intestinal strains demonstrated marked genetic diversity across phylogroups and capsular types. Major virulence genes were detected in 19.6% of strains, predominantly within the Kp1 phylogroup. Notably, principal PLA-associated clones ST23-KL1 and ST65-KL2 were identified among gut strains and exhibited hypervirulence in a murine model. However, two ST23-KL1 strains carried deletions in magA and displayed attenuated in vivo virulence, demonstrating significant intra-clonal diversity.ConclusionIntestinal carriage of K. pneumoniae is highly prevalent and genetically diverse in Taiwan, with hypervirulent and multidrug-resistant strains present in the community. The association of virulence genes with anti-phagocytosis and adhesion phenotypes underscores the gut as a reservoir for clinically important clones. Ongoing surveillance of intestinal K. pneumoniae is warranted to monitor the emergence and evolution of pathogenic and resistant bacteria.