Abstract
BackgroundRapid diagnostic tests (RDT) for cholera are promising tools for detecting cholera in areas with limited laboratory infrastructure. However, evidence on the characteristics of the many available RDTs is scarce, and their use has been limited by suboptimal performance. We evaluated the performance characteristics of three cholera RDTs from Span Diagnostics, Artron Laboratories, and Standard Diagnostics in a regional laboratory in Haiti.Methodology/Principal findingsWe retrospectively reviewed records from May 2014 to October 2015 of a laboratory-based surveillance program for Vibrio cholerae at Hôpital Saint-Nicolas in Saint-Marc, Haiti. We compared the results of 511 Crystal VC, 129 Artron and 451 SD Bioline RDTs to bacterial culture as the gold standard. Of 905 cultures, 477 (52.7%) were positive for V. cholerae O1, of which 27.7% were serotype Inaba. No cultures grew V. cholerae O139. Sensitivity and specificity of Crystal VC were 98.6% (95%CI: 96.5%-99.6%) and 71.1% (95%CI: 64.7%-76.9%), respectively. Artron demonstrated a sensitivity of 98.6% (95%CI: 92.7%-100%) and specificity of 69.1% (95%CI: 55.2%-80.9%). SD Bioline demonstrated a sensitivity of 81.1% (95%CI: 75.6%-85.8%) and specificity of 92.8% (95%CI: 88.4%-95.9%). Crystal VC and Artron frequently showed false positive O139 bands, whereas none were seen with SD Bioline.Conclusions/SignificanceThere is significant variation in the performance of different cholera diagnostic RDTs. Artron and Crystal VC RDTs have high sensitivity and low specificity, while SD Bioline RDT has low to moderate sensitivity and high specificity when performed by laboratory technicians in Haiti. Study limitations included its retrospective design. The suboptimal characteristics of these tests limit their use as clinical point-of-care tests; however, they may be useful in outbreak response, surveillance, and research in resource-limited settings.
Highlights
Cholera remains a significant cause of morbidity and mortality worldwide, resulting in an estimated 2.8 million cases and 91,000 deaths annually.[1]
Between the period of May 1st, 2014 and October 15th, 2015, 910 specimens from patients presenting for acute watery diarrhea at the study site underwent testing for V. cholerae. (Fig 1) Of the 910 documented specimens, 905 had a documented result for bacterial culture and were included in the analysis. 3 specimens had no documented bacterial culture performed and 2 had incompletely documented results and so were excluded from the analysis. (Fig 1) 455 bacterial cultures were performed with alkaline peptone water (APW) enrichment and 450 without APW
568 SD Bioline Rapid diagnostic tests (RDT) were performed; 451 were included in the analysis, and 117 were excluded because these tests were performed past their expiration date. (Fig 1) RDT test results for the detection of V. cholerae O1 and O139 are listed in Table 2. 349 of the 511 Crystal VC RDTs and 428 fo the 451 SD Bioline RDTs, and 9 of the 129 Artron RDTs were compared to bacterial cultures that did not go APW enrichment. (S1 Table) For a list of the number of specimens tested by different combinations of RDTs see S2 Table
Summary
Cholera remains a significant cause of morbidity and mortality worldwide, resulting in an estimated 2.8 million cases and 91,000 deaths annually.[1]. Prompt identification of cholera cases facilitates rapid outbreak responses in the short term, while providing reliable surveillance data to guide long-term policies and interventions To this end, microbiological stool culture, the current recognized gold standard for the diagnosis of cholera has significant limitations.[4] Culture to isolate and identify the causative bacterium, Vibrio cholerae, may take up to 3 days to complete and requires laboratory capacity that is often absent in underserved settings.[5] the accuracy of culture methods and their reliability as gold standards are increasingly being called into question due to their suboptimal sensitivity.[3,5,6] PCR-based technologies, more accurate than stool culture, are rarely available in settings most afflicted by cholera.[5]. We evaluated the performance characteristics of three cholera RDTs from Span Diagnostics, Artron Laboratories, and Standard Diagnostics in a regional laboratory in Haiti
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