A screening algorithm for diagnosing bacterial gastroenteritis by real-time PCR in combination with guided culture.
We have introduced a real-time PCR for the simultaneous detection of Campylobacter jejuni, Salmonella spp., Shigella spp./enteroinvasive Escherichia coli and Yersinia enterocolitica in fecal samples in our routine laboratory. This new approach showed consistent results, with minimal inter-sample variation. When compared to conventional culture, the hands-on time decreased by 13 h/wk, and the median turnaround time drastically shortened from 73 to 29 h (P < .0001). Moreover, the detection rate of the targeted pathogens seemed to increase: the positivity rate registered over a twelve month period increased from 4.98% when using bacterial culture, compared to 8.56% when using real-time PCR (P < .0001). For antimicrobial susceptibility testing, samples that are found to be PCR positive are additionally cultured after the PCR result is known. Using this algorithm, we got a positive culture for 71.0% of the PCR positive samples. The samples missed by guided culture had significantly higher quantification cycle (Cq) values compared to the samples picked up by guided culture (P = .0003). Finally; we also tested the effect of extended sample storage on the performance of guided culture. Storage time prior to inoculation did have an effect on the positivity rate of culture; interestingly, these effects were clearly species-dependent.
Clinical Laboratory GZA, Department of Molecular Diagnostics, GZA St-Augustinus, Oosterveldlaan 24, 2610, Wilrijk, Belgium. Electronic address: philippe.vanlint@gza.be.
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Van Lint
Clinical Laboratory GZA, Department of Molecular Diagnostics, GZA St-Augustinus, Oosterveldlaan 24, 2610, Wilrijk, Belgium.
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De Witte
Clinical Laboratory GZA, Department of Molecular Diagnostics, GZA St-Augustinus, Oosterveldlaan 24, 2610, Wilrijk, Belgium.
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Ursi
Clinical Laboratory GZA, Department of Molecular Diagnostics, GZA St-Augustinus, Oosterveldlaan 24, 2610, Wilrijk, Belgium.
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Van Herendael
Clinical Laboratory GZA, Department of Molecular Diagnostics, GZA St-Augustinus, Oosterveldlaan 24, 2610, Wilrijk, Belgium.
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Van Schaeren
D000465:Algorithms; D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000175:diagnosis*; D001431:Bacteriological Techniques / Q000379:methods*; D005243:Feces / Q000382:microbiology*; D005500:Follow-Up Studies; D005759:Gastroenteritis / Q000175:diagnosis*; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013997:Time Factors
Campylobacter jejuni; Gastrointestinal infection; Molecular biology; Salmonella; Shigella; Yersinia