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An Allelotyping PCR for Identifying Salmonella enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium
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Plasmid profiling and incompatibility grouping of multidrug resistant Salmonella enterica serovar Typhi isolates in

Winnie C Mutai1, Peter G Waiyaki2, Samuel Kariuki2

  • 1Department of Medical Microbiology, School of Medicine, University of Nairobi, Nairobi, Kenya. winny@uonbi.ac.ke.

BMC Research Notes
|July 18, 2019
PubMed
Abstract

Insights

Multidrug-resistant Salmonella Typhi often harbor plasmids, primarily belonging to incompatibility group HI1. These plasmids can transfer antibiotic resistance, including to ampicillin, tetracycline, and chloramphenicol, to other bacteria.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Plasmids carrying antibiotic resistance genes are key drivers of multidrug-resistant (MDR) pathogen emergence.
  • Salmonella enterica serovar Typhi (S. Typhi) is a significant cause of typhoid fever, and MDR strains pose a growing public health threat.

Purpose of the Study:

  • To detect plasmids in MDR S. Typhi isolates.
  • To determine the incompatibility (Inc) groups of these plasmids.
  • To assess the potential for conjugation transmission of antibiotic resistance.

Main Methods:

  • Plasmid DNA was extracted from 98 MDR S. Typhi isolates using alkaline lysis.
  • Plasmid incompatibility grouping was performed via PCR replicon typing with 18 primer pairs.
  • Antibiotic resistance phenotypes were transferred to Escherichia coli K12F via conjugation.

Main Results:

  • Plasmids were present in 79.6% of the MDR S. Typhi isolates studied.
  • Incompatibility group HI1 was the most prevalent (93.6%), often co-occurring with IncFIC, IncP, and IncI1.
  • Resistance to ampicillin, tetracycline, and chloramphenicol was successfully transferred from MDR S. Typhi to E. coli K12F via conjugation.

Conclusions:

  • Plasmids, particularly IncHI1, are prevalent in MDR S. Typhi.
  • The presence of IncHI1 plasmids contributes to the MDR phenotype of S. Typhi.
  • Conjugation is a viable mechanism for the transmission of antibiotic resistance from S. Typhi.
Keywords:
ConjugationMultidrug resistant S. TyphiPlasmid incompatibility grouping

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