A Comparative Study Of Blood Culture And Widal Test In The Diagnosis Of Typhoid Fever In Febrile Patients

Introduction: Typhoid fever is a major health problem in developing countries. An accuraterndiagnosis on clinical grounds alone is difficult. In areas of endemicity, such as Ethiopia,rnbacterial culture facilities, definitive diagnosis for typhoid fever, are often unavailable. So,rnthe Widal test has been in use as the diagnostic assay. However, the value of the test for therndiagnosis of typhoid fever has been debated. So evaluating the result of Widal test isrnnecessary for correct interpretation of the result. In addition typhoid fever caused byrnmultidrug resistant strains of Salmonella typhi presents a serious problem in many developingrncountries.rnObjective: The main objective of this study is to compare the result of Widal test and bloodrnculture in the diagnosis of typhoid fever in febrile patients and to determine the antimicrobialrnpattern of isolates.rnMethodology: Data was collected from 277 febrile patients with symptoms clinically similarrnto typhoid fever visiting St. Paul’s General Specialized Hospitals from mid December 2010rnto March 2011. Blood was inoculated immediately after collection into 45ml of Trypton SoyrnBroth and further processed for the identification of S.typhi and S.paratyphi. Antimicrobialrnsusceptibility pattern of S. typhi and S. paratyphi isolates were determined by the modifiedrnKirby-Bauer disk diffusion technique. Slide agglutination test as screening test and tubernagglutination for the determination of antibody titer for reactive slide agglutinations samplesrnhave made. An antibody titer of ≥1:80 for anti TO and ≥1:160 for anti TH are taken as a cutrnof value to indicate recent infection of typhoid fever. Statistical software package for widowsrn(SPSS version 16) was used for analysis of the data and p value ≤0.05 was taken asrnsignificance.rnResult: A total of 277 febrile patients were recruited for this study, but data from 270 werernanalysed because the remaining seven patients have no full data to be processed. 186 (68.9rn%) were females and 84 (31.1 %) were males. 7 (2.6%) cases of S. typhi and 4 (1.5%) casesrnof S. paratyphi were identified with the total prevalence of typhoid fever 4.1 %. The totalrnnumber of patients who have indicative of recent infection by either of O and H antigensrnWidal test is 88 (32.6%). The sensitivity, specificity, PPV and NPV of Widal test are 71.4 %,rn68.44%, 5.7% and 98.9% respectively. Most (3/7[42.9%]) of the isolated S.typhi are highlyrnresistant to amoxicillin. All species are sensitive for norfloxacin and ceftriaxone. S. paratyphirnisolates show no resistance to gentamycine, tetracycline, norfloxacin and ciprofloxacin. Morernresistance (3 out of 4) is observed in amoxicillin. One species of S.typhi and 2 species of S.rnparatyphi are multi drug resistant.rnConclusion and recommendation: Widal test have a low sensitivity, specificity and PPV,rnbut it has good NPV which indicates that negative Widal test result have a good indication forrnthe absence of the disease. Hence, physicians should not totally depend on Widal test for therndiagnosis of typhoid fever and should use other alternative diagnostics such as clinicalrnknowledge to differentiate from other febrile infections. Regarding drug resistance both S.rntyphi and S. paratyphi showed high resistance for commonly used drugs against typhoidrnfever. Therefore, sensitivity test based prescription should be started to prevent therncontinuous drug resistance development.rnKey words: Widal test, blood culture, antimicrobial resistance, sensitivity, specificity,rnpositive predictive value, negative predictive value

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