The Rise of Extended-Spectrum β-Lactamase-Producing Ceftriaxone-Resistant Salmonella typhi in Western Rajasthan,
Kumar S Abhishek1, Alisha Aggarwal1, Vibhor Tak1
1Department of Microbiology, AIIMS, Jodhpur, India.
Infectious Disorders Drug Targets
|September 8, 2025
Summary
Emerging ceftriaxone resistance in Salmonella Typhi is a growing concern in India, driven by extended-spectrum beta-lactamase (ESBL) genes like blaCTX-M. This highlights the need for enhanced surveillance and infection control measures.
Area of Science:
- Microbiology
- Infectious Diseases
- Public Health
Background:
- Typhoid fever, caused by Salmonella Typhi, is a major health issue in developing nations.
- Antimicrobial resistance, including to fluoroquinolones and ceftriaxone, threatens effective treatment of typhoid fever.
Purpose of the Study:
- To investigate extended-spectrum beta-lactamase (ESBL)-producing Salmonella Typhi isolates.
- To identify specific ESBL genes and subtypes responsible for ceftriaxone resistance in Western Rajasthan, India.
Main Methods:
- Collected blood samples from patients with suspected typhoid fever.
- Performed antimicrobial susceptibility testing.
- Utilized PCR to detect ESBL genes (blaTEM, blaSHV, blaCTX-M) and blaCTX-M subtypes.
Main Results:
- 18 (22.8%) of 79 Salmonella Typhi isolates showed ceftriaxone resistance.
- blaCTX-M was the predominant ESBL gene (77.8% of resistant isolates), with blaCTX-M1, blaCTX-M15, and blaCTX-M10 identified.
- 48% of isolates were resistant to fluoroquinolones; chloramphenicol and co-trimoxazole showed re-emerging susceptibility (87%).
Conclusions:
- Ceftriaxone resistance in Salmonella Typhi is emerging in Western Rajasthan, mediated by ESBL genes, particularly blaCTX-M.
- The detection of blaCTX-M10 in Salmonella Typhi is a novel finding.
- Increased surveillance and infection control are crucial to combat the spread of antimicrobial resistance.
