1 Department of Medical Microbiology, Faculty of Medical Laboratory Science, University of Medical Sciences and Technology, Sudan.
2 Department of Medical Microbiology, Faculty of Medical Laboratory Science, University of Al-Butana, Rufaa, Sudan.
3 Department of Medical Microbiology, Faculty of Medical Laboratory Science, University Gezera, Sudan.
4 Department of Medicine, Faculty of Medicine, University of Al-Butana, Rufaa, Sudan.
5 Department of Basic Medical Sciences, Faculty of Medical Laboratory Science, Omdurman Islamic University.
* Corresponding Author
ORCID Details
Abdelhakam H. Ali: https://orcid.org/0000-0003-3984-8132
Mawada O. Ibrahim: https://orcid.org/ 0009-0000-7653-9297
Zeinab Hamid Mohamed: https://orcid.org/ 0000-0001-6121-9522
Yosria Mohammed Elsiddig: https://orcid.org/0009-0001-5492-292X
Mohamed Ali Zroog: https://orcid.org/0009-0009-5118-0308
Mohammed Abdelssalam Edrees: https://orcid.org/0009-0003-9531-7456
World Journal of Advanced Research and Reviews, 2026, 32(01), 1439–1452
Article DOI: 10.30574/wjarr.2026.32.1.2343
Received on 02 August 2026; revised on 18 October 2026; accepted on 20 October 2026
Background: A newly emerged pathogenic subtype, Hypervirulent Klebsiella pneumoniae (hvKp), can cause a series of severe, systemic invasive infections. Currently, a commonly used phenotypic indicator to clinically identify hvKp is hypermucoviscosity. The conventional method to detect this feature is the string test. This study aims to detect strains with the hypermucoviscous phenotype from clinically isolated Klebsiella pneumoniae strains, to determine the antimicrobial susceptibility patterns of these strains, and to detect two pathogenicity-related genes, ybtA and rmpA2.
Research Methods: A descriptive cross-sectional study. After obtaining clinically isolated Klebsiella pneumoniae strains, they were first inoculated on MacConkey agar for subculture, purification, and reidentification using standard biochemical tests. Next, the string test was used to detect the hypermucoviscosity of the strains, and then the Kirby–Bauer disc diffusion method to determine the antimicrobial susceptibility of the strains. Then, bacterial DNA was extracted using the boiling method. After extraction, multiplex PCR technology was used to detect the two pathogenicity-related genes, ybtA and rmpA2.
Results: A total of 76 Klebsiella pneumoniae isolates were analyzed in this study. The ybtA gene was detected in 48.7% (37/76) of the strains, while the rmpA2 gene was detected in 31.6% (24/76) of the samples. Among the test results, 12 strains (15.8%) showed a hypermucoviscous phenotypically; the remaining 64 strains (84.2%) did not have the hypermucoviscous property.
The antimicrobial resistance rates showed that ceftriaxone was the highest (93.4%), followed by gentamicin (68.4%). The resistance rates of classical cKps were all higher than those of hypervirulent hvKps: the resistance rate to gentamicin was 68.7% vs. 66.7%, to ceftriaxone was 93.7% vs. 91.7%, to meropenem was 35.9% vs. 33.3%, and to colistin was 45.3% vs. 16.7%.
Conclusion: This study confirms that both hypermucoviscous hvKp and classical cKp strains coexist among isolates. The detection rates of the two virulence-related genes, ybtA and rmpA2, are relatively high, indicating that key pathogenic traits persist in the studied strain population.
Hypervirulent Klebsiella pneumoniae, Classical Klebsiella pneumoniae, Hypermucoviscosity, String Test, Ybta, Rmpa2, Virulence Genes, Antimicrobial Resistance, Antimicrobial Susceptibility
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Abdelhakam Hassan Ali, Mawada Osman Ibrahim, Zeinab Hamid Mohamed, Yosria Mohammed Elsiddig, Mohamed Ali Zroog and Mohammed Abdelssalam Edrees. PHENOTYPIC AND MOLECULAR CHARACTERIZATION OF KLEBSIELLA PNEUMONIAE: HYPERMUCO¬VISCOSITY, ANTIMICROBIAL RESISTANCE, AND DETECTION OF YBTA AND RMPA2 VIRULENCE-ASSOCIATED GENES. World Journal of Advanced Research and Reviews, 2026, 32(01), 1439–1452. Article DOI: https://doi.org/10.30574/wjarr.2026.32.1.2343