Performance of molecular methods for the detection of Salmonella in human stool specimens
| Autor: | Angeziwa Chirambo, Ndaru Jambo, Marc Henrion, Melita A. Gordon, Robert S. Heyderman, Chisomo L. Msefula, Wilson Mandala, Arox W. Kamng’ona, Sandra Molina, Tonney S. Nyirenda, Miren Iturizza-Gomara |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Serotype
0301 basic medicine nontyphoidal Salmonella Salmonella polymerase chain reaction 030106 microbiology stool culture Selenite broth Medicine (miscellaneous) Biology Salmonella typhi medicine.disease_cause wc_269 Salmonella Typhi General Biochemistry Genetics and Molecular Biology law.invention Microbiology 03 medical and health sciences 0302 clinical medicine law Multiplex polymerase chain reaction wi_100 medicine diagnostics 030212 general & internal medicine bacteremia Polymerase chain reaction Articles Method Article medicine.disease DNA extraction Bacteremia gastrointestinal tract |
| Zdroj: | Wellcome Open Research |
| ISSN: | 2398-502X |
| Popis: | Background: The relationship between asymptomatic Salmonella exposure within the gastrointestinal tract and Salmonella bacteraemia is poorly understood, in part due to the low sensitivity of stool culture and the lack of validated molecular diagnostic tests for the detection of Salmonella in the stool. The study aimed to determine a reliable molecular diagnostic test for Salmonella in stool specimens. Methods: We optimised an in-house monoplex real-time polymerase chain reaction (PCR) for the detection of Salmonella ttr and InvA genes in stool by including a selenite broth pre-culture step for Salmonella before DNA extraction and validated their specificity against other local common pathogens. Then we assessed their performance against a well-validated multiplex PCR targeting the same ttr and InvA genes and against stool culture using clinical stool specimens collected from a cohort of 50 asymptomatic healthy Malawian children that were sampled at 1-month intervals over 12 months. We employed a latent Markov model to estimate the specificities and sensitivities of PCR methods. Results: Ttr and InvA primers were both able to detect all the different Salmonella serovars tested and had superior limits of detection when DNA was extracted after selenite pre-culture. Ttr sensitivity and specificity for monoplex-PCR were (99.53%, 95.46%) and for multiplex-PCR (90.30%, 99.30%) respectively. InvA specificity and specificity for using monoplex-PCR was (95.06%, 90.31%) and multiplex-PCRs (89.41%, 98.00%) respectively. Sensitivity and specificity for standard stool culture were 62.88% and 99.99%, respectively. Culture showed the highest PPV (99.73%), and monoplex-ttr had the highest NPV (99.67%). Conclusion: Test methods demonstrated high concordance, although stool culture and monoplexed ttr primers had superior specificity and sensitivity, respectively. The use of selenite pre-enrichment step increased Salmonella detection rate. Taken together, molecular detection methods used here could be used to reveal the true extent of both asymptomatic and symptomatic Salmonella exposure events. |
| Databáze: | OpenAIRE |
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