Azithromycin minimum inhibitory concentration (MIC) creep and clinical-microbiological profile of typhoidal and nontyphoidal Salmonella isolates from blood specimens at a tertiary care hospital in Pune, India.
- 1Department of Microbiology, Symbiosis Medical College for Women (SMCW), Symbiosis International (Deemed University), Pune, Maharashtra, India.
- 2Department of Medicine, Symbiosis Medical College for Women (SMCW), Symbiosis International (Deemed University), Pune, Maharashtra, India.
Abstract
Background and objectives The Salmonella strains causing bloodstream infection show wide genetic diversity together with different antibiotic resistance profiles worldwide. The response of typhoidal Salmonella to standard antimicrobial treatments has become increasingly concerning during the past few decades. This study was conducted to evaluate the occurrence rate, antibiotic susceptibility patterns, and clinical characteristics of patients with Salmonella bacteraemia in a tertiary care hospital in Pune, Maharashtra, India. Methods A cross-sectional study was conducted from March 2024 to March 2025, analysing blood culture-confirmed cases of enteric fever. All patients with Salmonella-positive cultures were included, and data were gathered from clinical and microbiology records. Results Out of 6,862 blood cultures processed, 42 (0.6%) tested positive for Salmonella species. Of these, 50% were Salmonella Typhi, 36% were Salmonella Paratyphi A, and the remaining 14% included S. Cholerasuis, S. Typhimurium, and S. Gallinarum. All S. Typhi and S. Paratyphi A isolates were fully susceptible to first-line antibiotics, including chloramphenicol, amoxicillin, and co-trimoxazole, as well as to ceftriaxone and cefixime. However, 78.5% of isolates showed reduced susceptibility to ciprofloxacin. Initial disc diffusion testing suggested potential azithromycin resistance in 11 isolates, but confirmatory E-strip testing found none to be resistant based on MIC values. One S. Paratyphi A isolate exhibited a notably high MIC of 24 µg/mL, which is not classified as resistant according to U.S. NARMS guidelines. Interpretation and conclusions The increasing azithromycin MIC values among typhoidal Salmonella indicate potential resistance development, so additional research should assess azithromycin susceptibility patterns in detail.
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BibTeX
@article{chavan2026azithromycin,
title = {{Azithromycin minimum inhibitory concentration (MIC) creep and clinical-microbiological profile of typhoidal and nontyphoidal Salmonella isolates from blood specimens at a tertiary care hospital in Pune, India.}},
author = {Sumit Sonaba Chavan and Kalpana Mohan Angadi and Varsha Shahane and Satyanand Kadloor},
journal = {The Indian journal of medical research},
year = {2026},
month = aug,
doi = {10.25259/ijmr_1311_2025},
url = {https://europepmc.org/article/MED/42851233},
note = {CC BY-NC-SA},
}
RIS
TY - JOUR
TI - Azithromycin minimum inhibitory concentration (MIC) creep and clinical-microbiological profile of typhoidal and nontyphoidal Salmonella isolates from blood specimens at a tertiary care hospital in Pune, India.
AU - Sumit Sonaba Chavan
AU - Kalpana Mohan Angadi
AU - Varsha Shahane
AU - Satyanand Kadloor
PY - 2026
DA - 2026/08/01
JO - The Indian journal of medical research
DO - 10.25259/ijmr_1311_2025
UR - https://europepmc.org/article/MED/42851233
AB - Background and objectives The Salmonella strains causing bloodstream infection show wide genetic diversity together with different antibiotic resistance profiles worldwide. The response of typhoidal Salmonella to standard antimicrobial treatments has become increasingly concerning during the past few decades. This study was conducted to evaluate the occurrence rate, antibiotic susceptibility patterns, and clinical characteristics of patients with Salmonella bacteraemia in a tertiary care hospital in Pune, Maharashtra, India. Methods A cross-sectional study was conducted from March 2024 to March 2025, analysing blood culture-confirmed cases of enteric fever. All patients with Salmonella-positive cultures were included, and data were gathered from clinical and microbiology records. Results Out of 6,862 blood cultures processed, 42 (0.6%) tested positive for Salmonella species. Of these, 50% were Salmonella Typhi, 36% were Salmonella Paratyphi A, and the remaining 14% included S. Cholerasuis, S. Typhimurium, and S. Gallinarum. All S. Typhi and S. Paratyphi A isolates were fully susceptible to first-line antibiotics, including chloramphenicol, amoxicillin, and co-trimoxazole, as well as to ceftriaxone and cefixime. However, 78.5% of isolates showed reduced susceptibility to ciprofloxacin. Initial disc diffusion testing suggested potential azithromycin resistance in 11 isolates, but confirmatory E-strip testing found none to be resistant based on MIC values. One S. Paratyphi A isolate exhibited a notably high MIC of 24 µg/mL, which is not classified as resistant according to U.S. NARMS guidelines. Interpretation and conclusions The increasing azithromycin MIC values among typhoidal Salmonella indicate potential resistance development, so additional research should assess azithromycin susceptibility patterns in detail.
SN - 0971-5916
ER -