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Antibiogram Profile of Salmonella enterica Serovar Typhi in India - A Two Year Study
Yashwant Kumar1, Anshu Sharma1, Kavaratty Raju Mani1
1National Salmonella and Escherichia Centre, Central Research Institute, Kasauli 173204, Himachal Pradesh, India.
Abstract:
Typhoid fever continues to remain a major health problem in the developing world, and the emergence of multidrug-resistant (MDR) strains has further reduced therapeutic options for treatment of the disease. The National Salmonella and Escherichia Centre in Kasauli, India received 128 Salmonella Typhi isolates during 2008-2009. These were evaluated for antimicrobial resistance, prevalent resistotypes and the proportion of MDR strains, using standard methods for 11 antimicrobials. An abrupt decrease in the proportion of MDR strains was observed. Only 4.7% of the isolates were found to be MDR with resistotypes chloramphenicol-ampicillin-streptomycin-nalidixic acid-trimethoprim (C-AS-Na-Tr) and chloramphenicol-ampicillin-nalidixic acid-trimethoprim (C-A-Na-Tr), which is very low compared to other studies from India. Nalidixic acid resistance was found to be present in 93.8% of the isolates. Moreover, the difference in the mean minimum inhibitory concentration (MIC) of ciprofloxacin for nalidixic acid-resistant and nalidixic acid-sensitive strains was found to be statistically significant (p<0.001), which calls into question the further use of ciprofloxacin for the treatment of typhoid fever because of potential treatment failures. The low proportion of MDR strains increases the possibility of first-line drugs for the treatment of typhoid fever.
Insights
Multidrug-resistant (MDR) typhoid fever strains decreased significantly in India. This suggests first-line drugs may become viable again for treating Salmonella Typhi infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Public Health
Background:
- Typhoid fever remains a significant global health issue, particularly in developing nations.
- The rise of multidrug-resistant (MDR) Salmonella Typhi strains has limited effective treatment options.
- Understanding antimicrobial resistance patterns is crucial for guiding therapeutic strategies.
Purpose of the Study:
- To evaluate antimicrobial resistance patterns and the prevalence of MDR Salmonella Typhi isolates in India.
- To assess the proportion of MDR strains and identify common resistotypes.
- To investigate the implications of nalidixic acid resistance on ciprofloxacin efficacy.
Main Methods:
- Analysis of 128 Salmonella Typhi isolates collected between 2008-2009.
- Standard antimicrobial susceptibility testing for 11 antimicrobials.
- Determination of prevalent resistotypes and the proportion of MDR strains.
Main Results:
- A notable decrease in MDR Salmonella Typhi strains was observed (4.7%).
- Prevalent MDR resistotypes included chloramphenicol-ampicillin-streptomycin-nalidixic acid-trimethoprim and chloramphenicol-ampicillin-nalidixic acid-trimethoprim.
- High prevalence of nalidixic acid resistance (93.8%) was detected.
- A statistically significant difference in ciprofloxacin MIC between nalidixic acid-resistant and sensitive strains was found (p<0.001).
Conclusions:
- The reduced proportion of MDR strains may allow for the re-emergence of first-line drugs for typhoid fever treatment.
- High nalidixic acid resistance raises concerns about the continued effectiveness of ciprofloxacin, potentially leading to treatment failures.
- Further monitoring of antimicrobial resistance in Salmonella Typhi is essential for public health interventions.
