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Updated: Oct 3, 2026
Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
Plasmid-mediated TEM-3 extended-spectrum beta-lactamase production in Salmonella typhimurium in Casablanca
Rajaa AitMhand1, Abdelaziz Soukri, Najat Moustaoui
1IbnRochd University Hospital, Casablanca, Morocco.
Abstract:
Isolates of extended-spectrum beta-lactamase (ESBL)-producing Salmonella typhimurium were recovered from children admitted to the IbnRochd University Hospital of Casablanca in 1994. These isolates produced TEM-3 as shown by PCR, isoelectric focusing and sequencing. Production of TEM-3 and resistance to gentamicin were encoded by a 10 kb plasmid that could be transferred by conjugation and transformation. This report extends the list of ESBLs produced by S. typhimurium and stresses the need for continuous surveillance of non-typhoidal Salmonella to adapt antibiotic treatment and preventive measures.
Insights
Extended-spectrum beta-lactamase (ESBL)-producing Salmonella typhimurium strains were found in children in Casablanca. These strains carried the TEM-3 enzyme on a transferable plasmid, highlighting the need for ongoing surveillance of non-typhoidal Salmonella.
Area of Science:
- Microbiology
- Infectious Diseases
- Molecular Biology
Background:
- Salmonella typhimurium is a significant cause of bacterial infections.
- Extended-spectrum beta-lactamases (ESBLs) confer resistance to crucial antibiotics.
- The emergence of ESBL-producing bacteria poses a global health threat.
Purpose of the Study:
- To identify and characterize ESBL-producing Salmonella typhimurium isolates from pediatric patients.
- To determine the genetic basis of ESBL production and associated resistance mechanisms.
Main Methods:
- Bacterial isolation and identification from clinical samples.
- Molecular techniques including PCR, isoelectric focusing, and DNA sequencing for ESBL characterization.
- Plasmid analysis and transfer experiments (conjugation and transformation).
Main Results:
- Multiple isolates of ESBL-producing Salmonella typhimurium were identified.
- The TEM-3 ESBL enzyme was detected in these isolates.
- A 10 kb plasmid carrying genes for TEM-3 production and gentamicin resistance was identified and shown to be transferable.
Conclusions:
- This study reports the presence of TEM-3 producing Salmonella typhimurium in a hospital setting.
- The findings underscore the importance of continuous surveillance for non-typhoidal Salmonella.
- Adapting antibiotic treatment and preventive strategies is crucial to combat antimicrobial resistance.
