Time of incubation of agar-plate culture for the diagnosis of Strongyloides stercoralis infection.

Agar-plate culture (APC) remains the most sensitive parasitological technique for S. stercoralis diagnosis. Although it was first described three decades ago, the time of incubation of the plates is neither a commonly described feature nor usually standardized. The aim of the study was to analyze the required time to detect S. stercoralis larvae in APC. A prospective laboratory-based study including all patients with at least one positive APC was performed. The plates were incubated at room temperature for 7 days. Clinical, analytical and parasitological features including results of the direct visualization of the stool (DV) after formalin-ether concentration and time-to-detection (TTD) of the larvae in APC were recorded. A total of 141 samples from 75 patients had a positive APC. In 49 of them (65.3%) three or more stool samples were processed for direct visualization (DV) and APC. Of these 49 patients, 8 (16.3%) were also diagnosed with DV and 41 (83.7%) were diagnosed only with APC. In 38 samples from 23 (30.7%) patients, the TTD was below 2 days, while in 27 samples from 13 (17.3%) patients, the larvae were detected on the 6th and 7th day. Direct visualization failed to detect S. stercoralis in most of the patients that were diagnosed with APC. Incubation periods below 2 and 5 days would miss an important percentage of infections. At least 7 days of incubation of the APC are required to detect presumably low-burden chronic infections in non-endemic countries. Copyright © 2021. Published by Elsevier B.V.

Citation

Isabel Fradejas, Juan María Herrero-Martínez, Manuel Lizasoaín, María Asunción Pérez-Jacoiste Asín, Ana Pérez-Ayala. Time of incubation of agar-plate culture for the diagnosis of Strongyloides stercoralis infection. Acta tropica. 2022 Feb;226:106220

Mesh Tags

Substances

PMID: 34757044

search → result