Plasmid mediated multidrug resistance in Salmonella typhi

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Typhoid fever, caused by Salmonella Typhi, is a significant global health concern.
• The emergence of multidrug-resistant (MDR) strains poses a therapeutic challenge.
• Monitoring antimicrobial resistance patterns is crucial for effective treatment strategies.

Purpose of the Study:

• To characterize the prevalence and resistance patterns of Salmonella Typhi isolates.
• To investigate the genetic basis of multidrug resistance in S. typhi.
• To assess the susceptibility of MDR strains to currently available antibiotics.

Main Methods:

• Isolation and identification of Salmonella Typhi from blood cultures of typhoid fever patients.
• Antimicrobial susceptibility testing using standard antibiotic panels.
• Plasmid-mediated resistance transfer experiments using conjugation with Escherichia coli K-12.

Main Results:

• 283 Salmonella Typhi isolates were collected between September 1989 and February 1991.
• 11% (44/283) of isolates exhibited MDR to chloramphenicol, ampicillin, co-trimoxazole, and tetracycline.
• Resistance was transferable 'en bloc' via plasmids in 40 of 44 MDR strains.
• All 44 MDR strains remained sensitive to ciprofloxacin and ofloxacin.

Conclusions:

• A significant proportion of S. typhi isolates displayed MDR to commonly used antibiotics during the study period.
• The plasmid-mediated nature of this resistance suggests a high potential for further dissemination.
• Fluoroquinolones like ciprofloxacin and ofloxacin represent effective therapeutic options against these MDR strains.