Trends in antimicrobial susceptibility of blood culture-positive typhoid fever over half a decade in adults attending a tertiary care teaching hospital in South India

Abstract

Background: Typhoid fever is a public health concern in developing countries. Developed countries have also been influenced due to tourism. The drugs used for treating typhoid fever can and have been rendered unusable due to resistance. Monitoring and updating the Salmonella antibiogram is needed to prevent therapeutic failures. This study confirms to the same goal.Methods: This study was conducted retrospectively in a tertiary care hospital in North Kerala with data collected from 2013 to 2017. Years were categorized into four quarters to analyze seasonality. Positive blood culture samples of adults, identified to be Salmonella typhi or paratyphi were subjected to antimicrobial sensitivity.Results: 37 Salmonella isolates were included. July-September quarter was found to have maximum incidence of typhoid fever followed by April-June quarter. All isolates were 100% sensitive to ceftriaxone, chloramphenicol, and amoxicillin-clavulanic acid. Sensitivity lacked for nalidixic acid (48.65%), ciprofloxacin (48.65%) and levofloxacin (70.27%). Sensitivity to ampicillin and cotrimoxazole was 86.49% and 91.89%. Azithromycin efficacy was good overall (94.59%) with resistant isolates emerging in final year of this study.Conclusions: Monsoon is most conducive for typhoid fever occurrence followed by summer. This study confirms utility of ceftriaxone and futility of quinolones and fluoroquinolones in typhoid fever treatment. Azithromycin has started showing emergence of resistance. Ampicillin and cotrimoxazole cannot be relied upon due to variability in sensitivity patterns. Chloramphenicol showed full efficacy throughout the study period which is encouraging. Amoxicillin-clavulinic acid, surprisingly was 100% effective throughout study period. However, no contemporary data is available for comparison.