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Multidrug-resistant Salmonella typhi: a worldwide epidemic
B Rowe1, L R Ward, E J Threlfall
1WHO Collaborating Centre for Phage Typing and Drug Resistance in Enterobacteria, Central Public Health Laboratory, London, United Kingdom.
Abstract:
Since 1989, strains of Salmonella typhi resistant to chloramphenicol, ampicillin, and trimethoprim (i.e., multidrug-resistant [MDR] strains) have been responsible for numerous outbreaks in countries in the Indian subcontinent, Southeast Asia, and Africa. MDR strains have also been isolated with increasing frequency from immigrant workers in countries in the Arabian Gulf, as well as in developed countries from returning travelers. In all MDR strains so far examined, multiple resistance has been encoded by plasmids of the H1 incompatibility group. As a result of the widespread dissemination of such strains, chloramphenicol can no longer be regarded as the first-line drug for typhoid fever. Because strains are also resistant to ampicillin and trimethoprim, the efficacy of these antibiotics has also been impaired, and ciprofloxacin is now the drug of choice for typhoid fever. Chromosomally encoded resistance to ciprofloxacin has now been observed in a small number of strains isolated in the United Kingdom from patients returning from the Indian subcontinent, and in at least one case the patient did not respond to treatment with this antibiotic. It is regrettable that resistance to ciprofloxacin has now emerged in MDR S. typhi, and it is of paramount importance to limit the unnecessary use of this vital drug so that its efficacy should not be further jeopardized.
Insights
Multidrug-resistant Salmonella typhi strains are causing global outbreaks. Emerging resistance to ciprofloxacin, the current drug of choice, necessitates careful antibiotic use to preserve treatment efficacy.
Area of Science:
- * Infectious Diseases
- * Microbiology
- * Antimicrobial Resistance
Background:
- * Multidrug-resistant (MDR) Salmonella typhi strains, resistant to chloramphenicol, ampicillin, and trimethoprim, have caused widespread outbreaks since 1989.
- * These MDR strains are prevalent in the Indian subcontinent, Southeast Asia, Africa, the Arabian Gulf, and are increasingly found in travelers returning to developed countries.
- * Resistance in MDR strains is typically plasmid-encoded, specifically by plasmids of the H1 incompatibility group.
Purpose of the Study:
- * To highlight the diminished efficacy of traditional antibiotics for typhoid fever due to MDR strains.
- * To identify ciprofloxacin as the current drug of choice for typhoid fever.
- * To report the emergence of chromosomal resistance to ciprofloxacin in MDR Salmonella typhi.
Main Methods:
- * Analysis of Salmonella typhi strains isolated from various geographical regions and patient populations.
- * Examination of resistance mechanisms, including plasmid-encoded resistance.
- * Clinical case observations of treatment outcomes with ciprofloxacin.
Main Results:
- * Chloramphenicol, ampicillin, and trimethoprim are no longer first-line treatments for typhoid fever due to widespread MDR strains.
- * Ciprofloxacin is now the recommended drug of choice for typhoid fever.
- * Chromosomally encoded resistance to ciprofloxacin has been identified in a small number of MDR Salmonella typhi strains, including cases with treatment failure.
Conclusions:
- * The emergence of ciprofloxacin resistance in MDR Salmonella typhi is a significant public health concern.
- * Prudent and limited use of ciprofloxacin is crucial to prevent further development and dissemination of resistance.
- * Continued surveillance and stewardship are essential to maintain the effectiveness of ciprofloxacin for treating typhoid fever.