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[The role and importance of plasmid resistance in certain pathogenic enterobacteria]
Abstract:
Conjugation, as a process of gene recombination where R-plasmids are transferred from resistant to sensitive genera of bacteria, is very important in the onset and development of infective multiple resistance to the bacterial division potential, whereas it enables fast spreading of resistant genera in the human population. Problems in regard to etiologic therapy of intestinal infections are most serious in shigellosis which is shown in our results of examining 450 genera of Shigella-sonnei isolated during the period January 1990-December 1994. Thus, resistance to ampicillin occurs in 99.4%, while resistance to streptomycin and cotrimoxazole occurs in 94%. Results of gene resistance transmission from Shigella-sonnei genera, potential donors into recipients by conjugation in vitro, show high frequency of transfer to ampicillin which points to the fact that it is determined by plasmids and transposons-mobile extrachromosomal gene structure. Similar results are gained by multiple-resistant genera of Salmonella wien. However, the stereotype which is dominant in our region and which makes more than 70% of all isolated salmonellas, Salmonella enteritidis is still sensitive to all most commonly used antimicrobial drugs. On the basis of gathered results it may be concluded that the antibiotics of choice in the etiologic therapy of intestinal infections are quinolone-norfloxacin and ciprofloxacin because the resistance which may occur is chromosomally determined.
Insights
Multiple drug resistance in bacteria like Shigella sonnei is a major concern for treating intestinal infections. Quinolones such as norfloxacin and ciprofloxacin are recommended due to chromosomally determined resistance.
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Bacterial conjugation facilitates the spread of antibiotic resistance genes, complicating the treatment of infectious diseases.
- Intestinal infections, particularly shigellosis, present significant therapeutic challenges due to high rates of antimicrobial resistance.
Purpose of the Study:
- To investigate the prevalence of antibiotic resistance in Shigella sonnei and Salmonella species.
- To examine the mechanisms of antibiotic resistance gene transfer via conjugation.
- To identify effective antimicrobial agents for treating intestinal infections.
Main Methods:
- Analysis of 450 Shigella sonnei isolates (1990-1994) for antibiotic resistance profiles.
- In vitro conjugation experiments to assess gene transfer frequency.
- Evaluation of resistance patterns in Salmonella wien and Salmonella enteritidis.
Main Results:
- Shigella sonnei exhibited high resistance rates: 99.4% to ampicillin, 94% to streptomycin, and 94% to cotrimoxazole.
- Ampicillin resistance transfer occurred frequently via conjugation, indicating plasmid and transposon involvement.
- Salmonella enteritidis remained sensitive to common antimicrobials, while Salmonella wien showed multiple resistance.
Conclusions:
- Antibiotic resistance, particularly to ampicillin in Shigella sonnei, is largely mediated by mobile genetic elements.
- Norfloxacin and ciprofloxacin (quinolones) are effective choices for treating intestinal infections, as resistance is chromosomally determined.