Development, confirmation, and application of a seeded Escherichia coli process control organism to validate Salmonella enterica serovar Typhi environmental surveillance methods

• DOI: 10.1371/journal.pone.0301624
• Publication Date: 2024-05-07T17:24:09Z
• Authors: Sarah E. Philo; Nicolette A. Zhou; Lorraine M. Lillis; Venkata Raghava; Dilip Abraham; Vinoth Kumar; Nirmal Kumar; Jonathan Rigby; Joanna Ciol Harrison; Christine S. Fagn...; Alexandra L. Kossik; Angelo Q. W. Ong; Rachael Swanstrom; Elisabeth Burnor; Bethel Demeke; Nicola K. Beck; Jeffry H. Shirai; Stephen J. Libby; David S. Boyle; Nicholas Feasey; Gagandeep Kang; John Scott Meschke
• Keywords: Salmonella enterica

Salmonella enterica serovar Typhi (S. Typhi) is the causative agent of Typhoid fever. Blood culture gold standard for clinical diagnosis, but this often difficult to employ in resource limited settings. Environmental surveillance waste-impacted waters a promising supplement surveillance, however validating methods challenging regions where S. concentrations are low. To evaluate existing environmental methods, novel process control organism (PCO) was created as biosafe surrogate. Using previous described qPCR assay, modified PCR amplicon staG gene cloned into E. coli. We developed target region that recognized by primers addition non-coding internal probe sequence. A multiplex reaction differentiates between typhoid and targets, with no cross-reactivity or inhibition two probes. The PCO shown mimic lab-based experiments concentration using primary wastewater: filter cartridge, recirculating Moore swabs, membrane filtration, differential centrifugation. Across all seeded at 10 CFU/mL 100 detected 100% replicates. similar quantification cycle (Cq) values across (Average = 32.4, STDEV 1.62). also wastewater collection sites Vellore (India) Blantyre (Malawi) endemic. All tested both countries were positive PCO. an effective way validate performance targeting surface water.