Conjugative plasmid mediating adhesive pili in virulent Klebsiella pneumoniae isolates

Background and objectives: Plasmids have been known to play a major role in the dissemination of antibiotic resistance and virulence associated genes in a microbial population. This study aimed to understand the pathogenic potential of these isolates and to determine whether a correlation exists between virulence and antibiotic resistance. Results: Out of the 25 virulent K. pneumoniae isolates 3 (12%) showed adherence to the human carcinoma cell line (CaCO-2). These isolates showed multidrug resistance. The plasmid profile of these isolates showed a common large plasmid weighing 210 MDa. Conjugation experiment revealed that transconjugants exhibited adherence and some resistance markers. Interestingly, adherence of donors and transconjugants was transferable via pili as confirmed by the electron microscopy. Type 3 pili was detected in K120 isolate and the corresponding transconjugant that showed the highest adhesion indices. This was supported by Western blot technique confirming the role of type 3 pili as an adhesive factor. Conclusions: It appeared that type 3 pili on the surface of the K. pneumoniae isolates, which mediated attachment of the bacteria to the host cells, were plasmid encoded and this plasmid could be transferred by conjugation and expressed by the transconjugants.

Author(s): Fatma I. Sonbol, Tarek E. El-Banna, Ahmed A. Abd El- Aziz, and Lamiaa A. Al-Madboly*

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