Ciprofloxacin resistance and bile-induced biofilm enhancement in Salmonella paratyphi A isolates

Background

Salmonella paratyphi A is a significant human pathogen responsible for paratyphoid fever which affects millions globally, particularly in regions with limited clean water and sanitation access.

Methodology

The blood samples were cultured on MacConkey agar and identified by biochemical tests and an API 20E kit. Antimicrobial susceptibility was performed according to CLSI guidelines using different antibiotics and minimum inhibitory concentrations (MIC) for ciprofloxacin were determined using agar dilution. The biofilm-forming ability of isolates was performed, and the effect of bile salts on biofilm production was also tested. Extracellular polysaccharides from select isolates were extracted and analyzed via Fourier Transform Infrared Spectroscopy to characterize their chemical properties.

Results

The highly infected age group with S. paratyphi A was 21–40 and showed 42 % prevalence. All the isolates showed resistance to nalixidic acid and 22 % isolates to ciprofloxacin. The isolates dose-dependent inhibition with different MIC values for ciprofloxacin in the range of 8 μg/ml to 1024 μg/ml. The isolates showed variations in biofilm formation, most of them were moderate biofilm producers, around 32 % and 28 % of the isolates were strong biofilm producers. Additionally, we observed that bile salts treatment increase the biofilm forming ability of isolates.

Conclusion

The study highlighted the prevalence and alarming rate of ciprofloxacin resistance among clinical Salmonella paratyphi A isolates. The biofilm formation analysis revealed that a significant proportion of S. paratyphi A isolates produced biofilms, which may contribute to their resistance and pathogenicity.