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

Chaudhry, Rama; Chandel, Dinesh S.; Verma, Nishant; Singh, Nidhi; Singh, Parul; Dey, Aparajit Ballav

doi:10.1099/jmm.0.020982-0

Cited by 11 publications

(9 citation statements)

References 13 publications

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“…In contrast to our findings, Nga et al did not detect S. Typhi (or S. Paratyphi A) in any blood samples with symptoms of enteric (typhoid) fever that were culture negative (23). However, other researchers have detected S. Typhi in culture-negative blood by using regular, nested, and real-time PCR platforms (4,11,18,22). Our data suggest that PCR is useful as a complementary form of diagnosis in the context of diagnostic evaluation and provides the advantage of being able to detect nonviable cells (e.g., in patients who have recently commenced antibiotics).…”

Section: Discussioncontrasting

confidence: 54%

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Evaluation of Serological Diagnostic Tests for Typhoid Fever in Papua New Guinea Using a Composite Reference Standard

Siba

Horwood

Vanuga

et al. 2012

Clin. Vaccine Immunol.

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b Typhoid fever remains a major global health problem. A major impediment to improving outcomes is the lack of appropriate diagnostic tools, which have not significantly improved in low-income settings for 100 years. We evaluated two commercially available rapid diagnostic tests (Tubex and TyphiDot), a prototype (TyphiRapid TR-02), and the commonly used single-serum Widal test in a previously reported high-burden area of Papua New Guinea. Samples were collected from 530 outpatients with axillary temperatures of >37.5°C, and analysis was conducted on all malaria-negative samples (n ‫؍‬ 500). A composite reference standard of blood culture and PCR was used, by which 47 participants (9.4%) were considered typhoid fever positive. The sensitivity and specificity of the Tubex (51.1% and 88.3%, respectively) and TyphiDot (70.0% and 80.1%, respectively) tests were not high enough to warrant their ongoing use in this setting; however, the sensitivity and specificity for the TR-02 prototype were promising (89.4% and 85.0%, respectively). An axillary temperature of >38.5°C correlated with typhoid fever (P ‫؍‬ 0.014). With an appropriate diagnostic test, conducting typhoid fever diagnosis only on patients with high-grade fever could dramatically decrease the costs associated with diagnosis while having no detrimental impact on the ability to accurately diagnose the illness.

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Section: Discussioncontrasting

confidence: 54%

“…In recent years, molecular biology-based assays have been evaluated in trials for the detection of S. Typhi in blood (4,11,18,22). The application of such methods in routine diagnosis for typhoid fever is yet to be established; however, nucleic acid diagnostic assays can offer high sensitivity and excellent specificity.…”

mentioning

confidence: 99%

Evaluation of Serological Diagnostic Tests for Typhoid Fever in Papua New Guinea Using a Composite Reference Standard

Siba

Horwood

Vanuga

et al. 2012

Clin. Vaccine Immunol.

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“…Typhi , fliC-a for S . Paratyphi A) have been most commonly targeted, but an array of alternative PCR gene targets have been assessed [59–63]. Parry et al .…”

Section: Available Diagnostic Approaches For Enteric Fevermentioning

confidence: 99%

Diagnostics for invasive Salmonella infections: Current challenges and future directions

Andrews

Ryan

2015

Vaccine

119

136

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Invasive Salmonellosis caused by Salmonella enterica serotype Typhi or Paratyphi A, B, C, or invasive non-typhoidal Salmonella serotypes, is an immensely important disease cluster for which reliable, rapid diagnostic tests are not available. Blood culture remains the gold standard but is insensitive, slow, and resource-intensive. Existing molecular diagnostics have poor sensitivity due to the low organism burden in bodily fluids. Commercially available serologic tests for typhoidal Salmonella have had limited sensitivity and specificity. In high burden, resource-limited settings, reliance on clinical diagnosis or inaccurate tests often results in frequent, unnecessary treatment, which contributes selective pressure for the emergence of antimicrobial resistance. This practice also results in inadequate therapy for other etiologies of acute febrile illnesses, including leptospirosis and rickettsial infections. A number of novel serologic, molecular, transcriptomic and metabolomic approaches to diagnostics are under development. Target product profiles that outline specific needs may focus development and investment, and establish benchmarks for accuracy, cost, speed, and portability of new diagnostics. Of note, a critical barrier to diagnostic assay rollout will be the low cost and low perceived harm of empiric therapy on behalf of providers and patients, which leaves few perceived incentives to utilize diagnostics. Approaches that align incentives with societal goals of limiting inappropriate antimicrobial use, such as subsidizing diagnostics, may be essential for stimulating development and uptake of such assays in resource-limited settings. New diagnostics for invasive Salmonellosis should be developed and deployed alongside diagnostics for alternative etiologies of acute febrile illnesses to improve targeted use of antibiotics.

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“…The sensitivity of PCR without enrichment in blood-culture positive cases has exceeded 90% in some studies (271,273,(278)(279)(280)(281)(282)(283)(284)(285)(286), although other studies have reported much lower sensitivities more consistent with the number of bacteria in the blood (266,272,287). Bone marrow aspirates were examined in one study, with 100% sensitivity (287), and positive results have also been found in urine samples (288).…”

Section: Molecular Assaysmentioning

confidence: 99%

“…Nucleic acid amplification tests, including conventional PCR and real-time PCR, have been developed for the detection of both Salmonella serovars Typhi and Paratyphi A, mainly in blood (271)(272)(273)(274)(275)(276)(277)(278)(279)(280)(281)(282)(283)(284)(285)(286)(287)(288). Nucleic acid amplification methods have the potential to amplify small numbers of organisms and nonculturable bacteria, as well as dead organisms.…”

Section: Molecular Assaysmentioning

confidence: 99%

Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

et al. 2015

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SUMMARY Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica , initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015.

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

Cited by 11 publications

References 13 publications

Evaluation of Serological Diagnostic Tests for Typhoid Fever in Papua New Guinea Using a Composite Reference Standard

Evaluation of Serological Diagnostic Tests for Typhoid Fever in Papua New Guinea Using a Composite Reference Standard

Diagnostics for invasive Salmonella infections: Current challenges and future directions

Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

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