Synergistic Effect of Combination Antibiotics against Multidrug-Resistant Salmonella enterica serovar Typhi

Authors

  • Sufia Islam Department of Pharmacy, East West University, Plot No-A/2, Jahurul Islam City, Aftabnagar, Dhaka 1212, Bangladesh
  • Azima Sultana Julie Department of Pharmacy, East West University, Plot No-A/2, Jahurul Islam City, Aftabnagar, Dhaka 1212, Bangladesh
  • Atkiya Nazifa Department of Pharmacy, East West University, Plot No-A/2, Jahurul Islam City, Aftabnagar, Dhaka 1212, Bangladesh
  • Marjana Khalil Department of Pharmacy, East West University, Plot No-A/2, Jahurul Islam City, Aftabnagar, Dhaka 1212, Bangladesh.
  • Muhammad Asaduzzaman School of Pharmacy, BRAC University, kha-208, Bir Uttam Rafiqul Islam Ave, Dhaka 1212, Bangladesh

Keywords:

Drug resistance, Salmonella enterica serovar typhi, Shigella flexneri, synergistic effects, zone of inhibition

Abstract

Background: Infection caused by multidrug-resistant (MDR) Salmonella enterica serovar Typhi (S. Typhi) is a major health problem in low- and middle-income countries (LMICs). S. Typhi has been reported to be resistant to fluoroquinolones and cephalosporins. Objective: To find out the anti-microbial activity of combination antibiotics against resistant S. typhi. Materials and Methods: First, single antibiotic disks of ciprofloxacin, imipenem and vancomycin with the concentrations of 20, 40, 60 and 80 μg/ml were prepared and applied against sensitive S. typhi to confirm its susceptibility. Later, a resistant strain of Shigella flexneri was treated with single antibiotic (ciprofloxacin, vancomycin and imipenem) at the highest concentration (80 μg/ml) to determinets resistant behavior by measuring the zones of inhibition obtained from the disc diffusion assay. Co-culture was performed between the sensitive and resistant strains to develop the resistant strain of S. typhi. Combinations of antibiotics were used for susceptibility testing against the newly resistant strain of S. typhi by using Kirby–Bauer disk diffusion method. Experiments were carried out in triplicates and the average reading was recorded. Results: The study showed that different concentrations of the combination of vancomycin and imipenem (20, 40, 60, 80 μg/ml) exhibited 18, 20, 24- and 29-mm respective zone of inhibition (ZOI) against S. typhi. A combination of ciprofloxacin and imipenem also exhibited optimum ZOI. It was observed in this study that a single antibiotic treatment did not show any activity against newly resistant strains of S. typhi. Conclusions: The combination therapy can be used as a beneficial treatment approach in multi-drug resistant S. typhi infections.

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Published

2024-07-14