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Published on: January 4, 2017
Colicinogeny in local isolates of salmonellae and plasmid transfer studies
1Department of Biological Sciences, Middle East Technical University, Ankara, 06531, Turkey.
Abstract:
Colicinogeny was determined in local isolates of S. typhimurium and S. enteritidis. Fourteen out of 35 S. typhimurium isolates of hospital origin were colicin producers whereas only one chicken isolate out of 82 S. enteritidis isolates of various origin (human, chicken or egg) produced colicin. A colicin producing, cephalothin (Cpt)- and piperacillin (Prl)-resistant local isolate of Salmonella havana (H32) harbored 4 plasmids of 54.0, 28.4, 2.7 and 1.9 kb. Upon curing its plasmids, the strain lost the ability to produce colicin and resistance to antibiotics and no longer expressed smooth lipopolysaccharide (LPS). The outer membrane protein (OMP) of 34.6 kDa was also lost. Using nalidixic acid (Nal)-resistant mutant of the cured strain in conjugation experiments, 10 out of 27 transconjugants were found to be resistant to Nal and Prl, 10 were resistant to Nal and Cpt and 7 showed Nal, Prl and Cpt resistance. Cpt and Prl resistance were determined by 54.0 and 28.4 kb plasmids, respectively. There was no direct correlation between plasmid contents and colicinogeny, LPS and OMP profiles.
Insights
Salmonella typhimurium and enteritidis colicinogeny varied by origin. A Salmonella havana strain
Area of Science:
- Microbiology
- Bacteriology
- Genetics
Background:
- Colicinogeny, the production of colicins, is a trait found in some bacterial strains.
- Antibiotic resistance in Salmonella species is a growing public health concern.
- Plasmids play a crucial role in the dissemination of antibiotic resistance and other traits in bacteria.
Purpose of the Study:
- To determine the prevalence of colicinogeny in local isolates of Salmonella typhimurium and Salmonella enteritidis.
- To investigate the role of plasmids in colicin production, antibiotic resistance, and outer membrane protein expression in Salmonella.
Main Methods:
- Colicin production was assessed in S. typhimurium and S. enteritidis isolates.
- Plasmid analysis was performed on a colicin-producing, antibiotic-resistant Salmonella havana isolate.
- Plasmid curing experiments and conjugation assays were conducted to determine plasmid function.
Main Results:
- Colicin production was more frequent in hospital-origin S. typhimurium (14/35) than in S. enteritidis (1/82).
- A Salmonella havana strain with colicin production and resistance to cephalothin and piperacillin harbored four plasmids.
- Plasmid curing resulted in loss of colicin production, antibiotic resistance, smooth lipopolysaccharide (LPS), and a 34.6 kDa outer membrane protein (OMP).
- Conjugation experiments indicated that cephalothin and piperacillin resistance were linked to 54.0 kb and 28.4 kb plasmids, respectively.
Conclusions:
- Plasmids are involved in mediating colicin production, antibiotic resistance, LPS, and OMP expression in Salmonella.
- Specific plasmids were identified as responsible for cephalothin and piperacillin resistance.
- No direct correlation was found between overall plasmid content and colicinogeny, LPS, or OMP profiles.
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