Comparison of Widal's test and bacterial culture as diagnostic tests for typhoid fever in humans and investigation of antimicrobial resistance of salmonella typhi isolates from patients attending private health facilities in Mbale City, Uganda

Abstract

Due to lack of microbiology facilities, private health facilities in Mbale City are still depending on the Widal’s test that is no longer recommended to diagnose typhoid fever, a disease that is responsible for about 200,000 to 600,000 annual deaths worldwide. Use of Widal’s test was discontinued in public health facilities, which are now adhering to the recommended guidelines of using culture and sensitivity testing. Dependency on Widal’s test has led to inappropriate typhoid diagnosis and drug prescription; as well as contributing to antibiotic resistance development to first line antibiotics like chloramphenicol. The aim of the study was to determine the predictive values of Widal’s test against culture and the antimicrobial sensitivity profile of Salmonella typhi (S. typhi) isolates from patients attending private health facilities in Mbale city. The study attracted 172 participants, whose blood and faecal samples were cultured and results compared with those of Widal’s test. The isolates were then subjected to Ciprofloxacin, Imipenem, Ceftriaxone, Erythromycin, Chloramphenicol and Augmentin for sensitivity testing. The positive predictive value (PPV) for Widal’s test was 6.8% while the negative predictive value (NPV) was 100%. Three isolates were sensitive to Ciprofloxacin (3, 100%) and Imipenem (3, 100%), intermediate to Ceftriaxone (2, 67%) and resistant to Erythromycin (3,100%), Chloramphenicol (2, 67%) and Augmentin (2, 67%). In comparison with the culture as the gold standard, Widal’s diagnostic sensitivity, specificity, positive predictive and negative predicative values included 100%, 76%, 6.8% and 100% respectively. It should therefore be used to rule out typhoid fever and not diagnosis or followed up with a more specific confirmatory test. Salmonella typhi was highly sensitive (100%) to both Ciprofloxacin and Imipenem; and resistant (100%) to Erythromycin. The treatment plan for typhoid fever could be reviewed to omit resistant drugs.