[Mechanism of multiresistant Salmonella typhi]

Area of Science:

• Microbiology
• Molecular Biology
• Epidemiology

Context:

• Salmonella typhi (S. typhi) infections pose a significant public health challenge.
• Antibiotic resistance in S. typhi is a growing concern globally.
• This study investigated S. typhi strains from Qingpu County, Shanghai.

Purpose:

• To characterize the antibiotic resistance patterns of S. typhi strains.
• To identify potential genetic mechanisms underlying multidrug resistance.
• To determine the prevalent phage types of S. typhi in the study area.

Summary:

• 142 S. typhi strains were isolated from 1988-1989.
• Most strains were sensitive to ceftazidime, ceftriaxone, ofloxacin, and enoxacin.
• 22 strains exhibited multidrug resistance (MDR) to chloramphenicol, co-trimoxazole, ampicillin, cefazolin, gentamicin, piperacillin, and tetracycline.
• Beta-lactamase production was implicated in resistance to beta-lactam antibiotics.
• A 98Md plasmid was detected in all MDR strains and conjugates, suggesting its role in MDR.
• The M1 phage type was most prevalent and associated with resistance to chloramphenicol, co-trimoxazole, and ampicillin.

Impact:

• Highlights the emergence of MDR S. typhi strains in Shanghai.
• Identifies a specific plasmid (98Md) as a potential key factor in S. typhi multidrug resistance.
• Suggests a link between the M1 phage type and specific antibiotic resistance profiles.
• Provides valuable data for guiding antimicrobial therapy and surveillance strategies for typhoid fever.