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

Hayder  Ali; Dhuha Mahdi  Jabir; Zainab  Falih; Salam  Najm

doi:10.18502/ijm.v17i5.19882

Hayder Ali Department of Biology, College of Science, University of Al-Qadisiyah, Al Diwaniyah, Iraq
Dhuha Mahdi Jabir Department of Biology, College of Science, University of Al-Qadisiyah, Al Diwaniyah, Iraq
Zainab Falih Department of Biology, College of Science, University of Al-Qadisiyah, Al Diwaniyah, Iraq
Salam Najm Department Diwaniyah Health, Ministry of Health, Al Diwaniyah, Iraq

DOI: https://doi.org/10.18502/ijm.v17i5.19882

Keywords: Klebsiella pneumonia; Hypermucoviscosity; Bacterial capsules; rmpA gene; Virulence

Abstract

Background and Objectives: Hypermucoviscous Klebsiella pneumoniae exhibits distinct phenotypic and genetic char- acteristics 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 mem- bers 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.