Phenotypic and genotypic analysis of hypermucoviscous Klebsiella pneumoniae (hmkp) strain.

BACKGROUND AND

OBJECTIVES

Hypermucoviscous Klebsiella pneumoniae exhibits distinct phenotypic and genetic characteristics that distinguish it from the classic K. pneumoniae pathogen. The aim of current study was to investigate some phenotypic and genetic markers used for hmKp identification.

MATERIALS AND

METHODS

Seventy-one K. pneumoniae isolates were obtained from the respiratory care unit in Al-Diwanyiah Teaching Hospital \Diwanyah, Iraq, from the first of November 2024 to the first of March 2025. The bacteria were identified, and antibiotic sensitivity testing was performed using VITEK 2 ID-GN and AST cards. Hypermucoviscosity was assessed using the string test, and an investigation into several adherence and virulence genes was conducted for all isolates. Then, multi-locus sequence typing was performed for hypermucoviscous K. pneumoniae isolates.

RESULTS

3 (4.22%) of 71 isolates were hypermucoviscous. The virulence and adherence genes were present in 100% of the isolates, whereas rmpA was only found in hypermucoviscous isolates. The results showed that the hmKp isolates were members of clonal group 147 (CG147) and were assigned to sequence type (ST) 293.

CONCLUSION

The string test is the primary phenotypical diagnosis for hmKp, while the genetically encoded rmpA gene is the most reliable genetic marker for hmKp identification. However, MLST is not beneficial for identification. The central positioning of ST392 within the MST highlights its potential role as an emerging high-risk clone.