Rapid Diagnosis Of Typhoid Fever Research Articles

A comparative evaluation of rapid card and widal slide agglutination tests for rapid diagnosis of typhoid fever

Background: Typhoid fever is a serious public health problem. It causes severe systemic infection in lesser developed areas of the world. Although blood culture is regarded as the gold standard for diagnosis, it is a time taking procedure. An early and accurate diagnosis is necessary for an effective treatment. Aims: The present study was done to comparatively evaluate rapid card and Widal slide agglutination tests for rapid diagnosis of typhoid cases. Settings and Design: The study design was a cross-sectional descriptive study done over a period of 6 months from January to June 2018. Materials and Methods: A total of 265 patients suspected of typhoid fever who gave their consent were included in the study whose blood samples were tested by both rapid card and Widal slide agglutination tests. Statistical Analysis Used: The collected data were analyzed using SPSS Data Editor Software version 20. Percentage of variables was calculated. Results: Of 265 patients, 97 patients were positive by the Widal slide test, whereas 113 patients were positive by the rapid card test, with 96.9% sensitivity and 88.7% specificity. Of 113 positives, 83 cases were positive for immunoglobulin M (IgM) only, whereas 30 cases were positive for both IgM and IgG. Conclusion: Rapid card test is a simple and easy to perform the diagnostic test for rapid detection of typhoid cases with an additional advantage of separate determination of IgM and IgG antibody, thereby aiding in identification of current infection and previous exposure so that appropriate and timely treatment could be given to the patients.

A comparative study of blood culture and immunochromatographic assay for rapid diagnosis of typhoid fever

Background and objectives: Typhoid fever, caused by Salmonella Typhi, is an important cause of morbidity and mortality in many developing countries including Bangladesh. As early diagnosis of disease and prompt treatment are essential for optimal management, a rapid method is urgently needed. Blood culture is the gold standard for diagnosis of typhoid fever, but it is time consuming. Immunochromatographic test (ICT) is easily accessible, cheap and simple method for diagnosis of typhoid fever, especially in the resource poor countries like Bangladesh.
 Methodology: 180 samples were collected from suspected typhoid fever cases. This study was conducted to isolate the S. Typhi by blood culture and to detect IgM and IgG antibody to S. Typhi by ICT method.
 Results: Out of 180 samples, 105(58.33%) were positive in ICT and 24(13.33%) were positive in blood culture. Considering blood culture as gold standard, the sensitivity, specificity, positive predictive value of ICT was 91.67%, 46.79%, 20.95% and 97.33% respectively.
 Bangladesh J Med Microbiol 2020; 14 (1): 7-10

A comparative study of Widal test and immunochromatographic assay for rapid diagnosis of typhoid fever in a tertiary care hospital

A comparative study of Widal test and immunochromatographic assay for rapid diagnosis of typhoid fever in a tertiary care hospital

A Comparative Evaluation of Different Diagnostic Modalities in the Diagnosis of Typhoid Fever Using a Composite Reference Standard: A Tertiary Hospital Based Study in Central India.

Enteric fever, caused by Salmonella spp. is a major cause of morbidity and mortality worldwide and endemic in many developing countries including India and other South-East Asian countries. Blood culture is regarded as the gold standard for diagnosis. Currently, the standard serological method is tube agglutination with moderate sensitivity and specificity. Dot blot assay detecting IgM and IgG antibodies to a specific 50kD Outer Membrane Protein (OMP) antigen of Salmonella spp. is a simple, reliable, affordable and rapid test which can help in the early diagnosis of typhoid fever. To systematically evaluate the different diagnostic modalities against a composite reference standard for the better diagnosis of typhoid fever in clinically suspected cases of typhoid fever. This cross-sectional, prospective analytical study was carried out at a tertiary care hospital attached to Medical College in central India from November 2011 to June 2013. A total of 163 blood samples, collected aseptically from patients clinically diagnosed of enteric fever, were tested using various component tests like blood culture, Tube Widal and Dot Enzyme Immuno Assay (Dot EIA) for IgG and/or IgM. Composite Reference Standard (CRS) was created for defining the confirmed cases of typhoid fever using the component tests, wherein culture positive and in absence of culture positivity any two component test positive patients were taken as confirmed cases. All the component tests were evaluated against the CRS for sensitivity, specificity, PPV and NPV and their significance in relation to the duration of illness using statistical tests of significance. Blood culture was positive in 16 (9.81%) whereas, Tube Widal, IgM, IgG and IgM+IgG in combination were positive in 88(54%), 58(35.58%), 30 (18.40%) and 75 (46.01%) respectively. Using a two test criteria of CRS framed, a total of 104 patients were considered as confirmed cases. Though specificity of blood culture was 100%, the sensitivity was low with significant detection rate in 1st week of illness. Tube Widal showed a sensitivity of 65.38% and specificity of 89.83% with significant detection rate in 2nd week. Dot blot assay for IgM, IgG and Combined IgM and IgG showed a sensitivity of 71.15%, 65.28% and 51.72% respectively whereas, the specificity was 10.16%, 47.45% and 74.57% respectively with significant detection rate in 2nd and 3rd week of illness. It can be concluded that though blood culture is still the gold standard, Dot blot assay found to have high sensitivity and good specificity might be a practical alternative test for the rapid diagnosis of typhoid fever if interpreted with care particularly using a composite reference standard. Further, it is reliable, simple to perform and rapid; results being available in 1 hour when compared to 48 hours for blood culture and 18 hours for Tube Widal test.

Validation of a new serology-based dipstick test for rapid diagnosis of typhoid fever

Currently, no reliable diagnostic test is available for typhoid fever. One serology-based dipstick test, developed indigenously, was validated in this study. Preserved sera from 336 fever patients with known culture results for Salmonella Typhi were blindly tested by the Widal test and the new assay. Analytical sensitivities, specificities, and efficiencies for the new assay versus the Widal test were 68.8% versus 62.5%, 71.1% versus 37.1%, and 70.5% versus 43.2%, respectively (p < 0.001), considering S. Typhi–positive samples as gold standards. Thereafter, fresh sera from 102 hospital-attending children with clinical typhoid fever (including 20 confirmed nontyphoidal cases as control) were tested by both methods and analyzed statistically. The diagnostic sensitivity, specificity, and efficiency were 51.2%, 85%, and 57.8% for the new assay, and 43.9%, 65%, and 48% for the Widal test, respectively. Overall performance ability of the new assay was not better than the Widal test (p > 0.5). Further improvement of the new point-of-care typhoid assay is recommended before implementation in the field setup.

IgM flow assay for detection of Typhoid Fever

A case-control study was carried out in the Department of Microbiology &amp; Immunology at BSMMU, Dhaka from July 2007 to June 2008 to validate IgM flow assay commercial diagnostic kits to assess the usefulness for the rapid diagnosis of typhoid fever. A total of 437 febrile patients clinically suspected of having typhoid fever were studied. Sixty cases were taken as controls, in which 30 were febrile controls (non-typhoidal febrile illness) and 30 were healthy controls. Among these 437 patients, Salmonella typhi was isolated from 58 (13.27%) cases .The isolation rate of S.typhi from blood was higher 21 (22.34%) in pediatric age group than that of the adult 37(10.78%); which is statistically significant (P&lt;0.003).The detection of specific LPS antibody (IgM flow assay) were evaluated in 58 culture proven cases,42 high Widal titre patients and 60 controls. The sensitivity of LPS antibody and Widal test was 91% and 54% respectively and specificity was 100% and 91.66% respectively. The serological assays based on the detection of IgM antibodies against serotype Typhi LPS had a significantly higher sensitivity and specificity than Widal test when used with a single acute phase serum sample(P&lt;0.007). So, these test involving detection of anti-LPS antibodies could be of use for the diagnosis of typhoid fever in patients who have clinical typhoid fever but are negative in culture or in regions where bacterial culturing facilities are not readily available.DOI: http://dx.doi.org/10.3329/bjmm.v6i1.19362 Bangladesh J Med Microbiol 2012; 06(01): 18-21

Comparison of a rapid commercial test, Enterocheck WB®, with automated blood culture for diagnosis of typhoid fever

Rapid diagnosis of typhoid fever is very important in the timely initiation of therapy. To evaluate the sensitivity and specificity of the Enterocheck WB(®) test. In a prospective study, the sensitivity and specificity of Enterocheck WB(®) that detects IgM antibodies to Salmonella typhi were compared with blood culture using BacT/Alert. Four hundred and fifty patients with suspected typhoid fever were assessed both by blood culture and Enterocheck WB(®); 100 of them were either Enterocheck WB(®)-positive or blood culture-positive or both for S. typhi. Both tests were positive in 47 of the 100 patients. In 45 patients, Enterocheck WB(®) was positive but blood culture was negative. In eight cases, Enterocheck was negative but blood culture was positive. Using blood culture as the gold standard, the sensitivity of Enterocheck WB(®) was 85.5%, specificity 88.6%, negative predictive value 97.7% and positive predictive value 51.1%. The Enterocheck WB(®) test can be performed at the bedside in 15 minutes and is a useful rapid method for diagnosis of typhoid fever.

Rapid diagnosis of typhoid fever by an in-house flagellin PCR

Rapid diagnosis of typhoid fever by an in-house flagellin PCR

The TUBEX test detects not only typhoid-specific antibodies but also soluble antigens and whole bacteria

TUBEX (IDL Biotech) is a 5 min semiquantitative colorimetric test for typhoid fever, a widely endemic disease. TUBEX detects anti-Salmonella O9 antibodies from a patient's serum by the ability of these antibodies to inhibit the binding between an indicator antibody-bound particle and a magnetic antigen-bound particle. Herein, we report that TUBEX could also be used to specifically detect soluble O9 lipopolysaccharide in antigen-spiked buffer by the ability of the antigen to inhibit the same binding between the particles. Sensitivity of antigen detection was improved (8-31 mug ml(-1)) by using a modified protocol in which the test sample was mixed with the indicator particles first, rather than with the magnetic particles as for antibody detection. The antigen was also detectable in spiked serum and urine samples, albeit less well (2-4-fold) than in buffer generally. However, no antigen was detected from six typhoid sera examined, all of which had anti-O9 antibodies. In addition, whole organisms of Salmonella Typhi (15 strains) and Salmonella Enteritidis (6 strains) (both O9(+) Salmonella), grown in simulated blood broths or on MacConkey agar, were also detectable by TUBEX when suspended at >9 x 10(8) organisms ml(-1). Expectedly, Salmonella Paratyphi A (7 strains), Salmonella Typhimurium (1 strain) and Escherichia coli (2 strains) were negative in the test. Thus, the same TUBEX kit may be used in several ways both serologically and microbiologically for the rapid diagnosis of typhoid fever. However, validation of the newer applications will require the systematic examination of real patient and laboratory materials.

Amplification of ST50 gene using dry-reagent–based polymerase chain reaction for the detection of Salmonella typhi

Conventional polymerase chain reaction (PCR) testing requires many pipetting steps and has to be transported and stored in cold chain. To overcome these limitations, we designed a ready-to-use PCR test for Salmonella typhi using PCR reagents, primers against the ST50 gene of S. typhi, a built-in internal amplification control (IAC), and gel loading dye mixed and freeze-dried in a single tube. The 2-step dry-reagent–based assay was used to amplify a 1238-bp target gene and an 810-bp IAC gene from 73 BACTEC blood culture broths (33 true positives for S. typhi and 40 true negatives for non- S. typhi). The sensitivity, specificity, positive predictive value, and negative predictive value of the PCR assay were 87.9%, 100%, 100%, and 90.9%, respectively. We suggest that this rapid 2-step PCR test could be used for the rapid diagnosis of typhoid fever.

Rapid diagnosis of typhoid fever by PCR assay using one pair of primers from flagellin gene of Salmonella typhi

Using the polymerase chain reaction (PCR) assay, we developed a rapid diagnosis method for Salmonella typhi infection in blood specimens from patients with typhoid fever. Primers were designed from the flagellin gene sequence, which would give an amplification product of 367 base pairs. In this study, the specificity of the assay, with no amplification, was seen for the other Salmonella strains with the flagellin gene, and not for non- Salmonella bacteria. For the sensitivity test, the protocol described allowed the detection of two to three copies of the Salmonella typhi genome, as determined by serial dilution of genomic DNA from Salmonella typhi. With the PCR technique, genomic DNA of Salmonella typhi was detected in 46 of 73 blood samples collected from patients with clinically suspected typhoid fever who had fever within 3 days of admission to the General Hospital, Makassar, South Sulawesi, Indonesia, and who had had no prior antibiotic treatment. The PCR results (63% positive cases) were compared with those of blood culture (13.7% positive cases) and the Widal test (35.6% positive cases), using the same samples from each of the 73 patients admitted to the General Hospital in Makassar. The time taken for PCR analysis of each sample was less than 12 h, compared with 3 to 5 days for blood or clot culture. The PCR with one pair of primers can be used as a novel, rapid diagnostic method for typhoid fever, particularly when results of standard culture assays are negative.

Rapid diagnosis of typhoid fever.

A Reverse Passive Haemagglutination Test (RPHA) was designed for the detection of Salmonella typhi antigen and rapid diagnosis of typhoid fever. Two per cent fresh sheep RBC's were coated with 32 micrograms/ml of immunoglobulin. The minimal detectable level of the antigen was 1250 micrograms/ml. Cross reactions were observed with the samples of patients suffering from Salmonella paratyphi A and pseudomonas infections. The RPHA established was used for the detection of S. typhi antigen in culture broths from 100 patients with clinically suspected typhoid fever with culture and/or widal positive, 50 patients with septicemia caused by bacteria other than S. typhi and 50 normal, afebrile healthy controls. It was found that the sensitivity and specificity of this assay was 70% and 92% respectively.

Low sensitivity of counter-current immuno-electrophoresis for serodiagnosis of typhoid fever.

Counter-current immuno-electrophoresis was evaluated as a diagnostic test for the serodiagnosis of typhoid fever with somatic (O), flagellar (H) and capsular polysaccharide (Vi) antigens of Salmonella typhi on the sera of patients who were blood culture positive (confirmed typhoid cases) or had high Widal agglutination titres, > or = 320, (presumptive typhoid cases). Of the 37 sera from confirmed cases, 30% showed positivity with O antigen, 24% with H antigens and 51% with Vi antigen. In patients with a presumptive diagnosis, 45% were positive for O antibody, 27% for flagellar antibody and 52% for Vi antibody. When all three antigens were combined the reactivity to any of the antigens was found to be 59% in confirmed typhoid cases, 79% in presumptive typhoid cases and 93% in patients who were simultaneously positive by blood culture and Widal agglutination. However, none of the sera from 45 controls gave a positive precipitation reaction with any of the antigens. It is concluded that counter-current immuno-electrophoresis is a rapid test with low sensitivity and high specificity with Vi antigen, a panel of antigens being most effective, and is, therefore, recommended for rapid diagnosis of typhoid fever.

Detection of Salmonella typhi by polymerase chain reaction.

A rapid and sensitive method for detection of Salmonella typhi would help in preventing the spread of outbreaks and in clinical diagnosis. In order to develop unique PCR primers to detect Salm. typhi, ribosomal RNA genes from Salm. typhi (Rawlings) were cloned in pUC18. The resulting clone was confirmed by sequencing. The cloned DNA fragment contained the 5S, part of the 23S rRNA genes and the 5S-23S spacer region (EMBL/GenBank accession No. U04734). It was expected that the 5S-23S spacer region is divergent unlike the highly conserved 23S + 5S genes. This was confirmed by comparison with the rRNA gene sequences in the EMBL/GenBank database. A pair of PCR primers specific for Salm. typhi was obtained, based on this spacer region sequence. The specificity of this pair of primers was tested with 54 Salm. typhi strains (of 27 different phage types). All these Salm. typhi strains showed the positive 300 bp PCR product with this pair of primers. Six other Salmonella species as well as six other non-Salmonella bacteria were tested and none showed the 300 bp PCR product. The sensitivity of the detection level was 0.1 pg of pure Salm. typhi genomic DNA, or approximately 40 Salm. typhi cells in a spiked food sample. This pair of primers therefore has the potential for development into a diagnostic tool for the rapid diagnosis of typhoid fever.

Development of nested PCR based on the ViaB sequence to detect Salmonella typhi

For a rapid diagnosis of typhoid fever, we developed a nested PCR based on the nucleotide sequence encoding the Vi antigen. All Salmonella typhi strains along with a Salmonella paratyphi C strain were PCR positive. This assay was able to detect S. typhi at the single-cell level.

Rapid diagnosis of typhoid fever by detection of Barber protein and Vi antigen of Salmonella serotype typhi.

Co-agglutination (coagg) and latex agglutination (LA) tests were used for the detection of Salmonella serotype Typhi Vi and Barber protein (BP) antigens in sera from five groups of individuals (A-E). Group A consisted of 30 blood culture-positive cases of typhoid fever and group B consisted of 30 suspected cases of typhoid fever who had sterile blood cultures but positive Widal tests. Thirty cases of pyrexia of unknown origin (PUO) were placed in group C, while group D consisted of 15 cases of septicaemia caused by organisms other than Salmonella serotype Typhi. Group E comprised 50 normal healthy individuals with no history of typhoid fever or TAB vaccination in the previous 5 years. The Vi-LA test performed best with 96.7% of group A sera and 90% of group B sera giving positive results. No false positive results and only 2.58% false negative results were obtained with this test. Considering patients with positive blood culture results or positive Widal tests as true positives, the sensitivities of the Vi-LA, BP-LA, Vi-coagg and BP-coagg tests were 93.3, 91.7, 83.3 and 86.7%, respectively. The specificities of these tests were 100, 98.5, 98.5 and 98.5%, respectively. It is suggested that the Vi-LA test can be used for the rapid and early diagnosis of typhoid fever.

Rapid diagnosis of typhoid fever by co-agglutination in an Indian hospital

Detection of Salmonella typhi infection by a co-agglutination assay for specific O, H and Vi antigens and by blood culture were compared for 110 patients with suspected typhoid fever. Blood cultures were positive for S. typhi in 25.5% of patients. Co-agglutination tests with patients' serum and with blood culture supernates gave positive results in 70.9% and 67.3% of cases respectively. S. typhi antigens Hd and O9 were detected in patients' serum by co-agglutination in 96.4% of blood culture-positive, and 62.2% of blood culture-negative patients. Co-agglutination results were uniformly negative with serum samples from a control group of 50 healthy individuals, 20 patients with febrile non-typhoid infectious disease and 20 patients with non-infectious febrile disease. Of the 25 patients with suspected typhoid fever who had not received prior antibiotic treatment, 88% yielded positive blood cultures and 96% gave positive results in serum co-agglutination tests. By contrast, of the 85 patients who had received prior antibiotics, only 7% yielded positive blood cultures, but 63.5% gave positive results in serum co-agglutination tests. Co-agglutination tests with serum offer a simple, rapid, sensitive, specific and economical method for the early diagnosis of typhoid fever.

Rapid diagnosis of typhoid fever through identification of Salmonella typhi within 18 hours of specimen acquisition by culture of the mononuclear cell-platelet fraction of blood

Detection of Salmonella typhi in blood by culture of the mononuclear cell-platelet layer was compared with other methods currently used for the diagnosis of typhoid fever. Colonies of S. typhi were present in all mononuclear cell-platelet layer-positive cultures within 18 h of plating and were identified within an additional 10 min by a coagglutination technique. In contrast, identification of all positive cultures by conventional blood culture required 3 days.

Production of Specific Monoclonal Antibodies to Salmonella typhi Flagellin and Possible Application to Immunodiagnosis of Typhoid Fever

Four murine monoclonal antibodies (MAbs) to Salmonella typhi flagellin were produced. These MAbs did not react with eight other enterobacterial strains tested: Salmonella enteritidis, Salmonella typhimurium, Salmonella paratyphi A, Escherichia coli, Shigella flexneri, Shigella sonnei, Yersinia enterocolitica, and Campylobacter jejuni. All four MAbs cross-reacted with Salmonella muenchen flagellin indicating specificity for d antigenic flagellar epitope. One MAb (C4) was selected to develop a double antibody sandwich enzyme-linked immunosorbent assay (ELISA) to detect S. typhi flagellin in serum samples. By use of this assay S. typhi flagellar antigen was detected in 95.5% of serum samples from patients with positive hemoculture for S. typhi, in 93.6% of samples from patients with positive serodiagnosis of typhoid fever, in 26% of samples collected from patients who were initially hemoculture-positive for S. typhi and who had undergone 7-8 d of chemotherapy, in 8.5% of samples from healthy persons from an endemic area, and in no samples from healthy persons from a nonendemic area. The presence of high levels of flagellin antibody titers did not interfere with the antigen detection. The detection of S. typhi flagellar antigen in patient serum may have practical value for rapid diagnosis of typhoid fever.

Evaluation in Papua New Guinea of a urine coagglutination test and a Widal slide agglutination test for rapid diagnosis of typhoid fever

Two simple rapid tests for the laboratory diagnosis of typhoid fever were evaluated, a coagglutination test for detecting Salmonella typhi antigens in urine and a Widal slide agglutination for detecting serum antibodies. Ninety-two culture-confirmed typhoid cases were compared with 64 non-typhoid fever patients, 50 close contacts of typhoid patients, 30 vaccinated staff and 72 healthy community members. A strong urine Vi coagglutination was found to be 86·5% sensitive and 91·8% specific for typhoid, but was not always easy to read. The slide Widal H was found to be 99% sensitive and 95% specific whereas the slide Widal O was 98% sensitive and 98% specific. These data suggest that a single slide Widal O, at a reciprocal titre of 40, is the most suitable rapid test for the diagnosis of typhoid in a population with low typhoid antibody levels in the community, few other cross-reacting Salmonella infections, and a tendency for patients to present late in the infection.