Comparative Feasibility Assessment of a Simplified Mossel EE–MacConkey Workflow for Detection of Enterobacteriaceae in Selected Non-Sterile Pharmaceutical Products

Abstract Microbiological quality control of nonsterile pharmaceutical products requires reliable detection of Enterobacteriaceae while maintaining operational feasibility in routine laboratory settings. Harmonized pharmacopoeial methods involve sequential procedures, including pre-enrichment, selective enrichment, and differential isolation. These steps increase analytical time and resource requirements. In this study, a simplified culture-based workflow consisting of pre-enrichment in Tryptic Soy Broth, selective enrichment in Mossel Enterobacteria Enrichment broth, and isolation on MacConkey agar was comparatively evaluated against harmonized pharmacopoeial procedures. The assessment was performed using Escherichia coli (ATCC 8739) and Salmonella typhimurium (ATCC 14028) inoculated into finished pharmaceutical products (pravastatin sodium and erlotinib tablets) and a raw material (paracetamol). Qualitative recovery of target microorganisms was observed in the evaluated finished products under both workflows. Comparable qualitative recovery patterns were observed under the experimental conditions evaluated. The simplified approach reduced total analysis time from six to 4 days and decreased estimated culture media costs from USD 340.25 to USD 95.99 per analysis. No recovery of E. coli was observed in paracetamol samples under either workflow. Neutralization also failed to restore microbial growth, suggesting potential matrix-associated inhibitory effects. Within the defined experimental scope, the proposed approach proved practically applicable to the evaluated matrices. However, the study was limited to two finished pharmaceutical products and one pharmaceutical raw material. Therefore, broader applicability requires further evaluation across a wider range of pharmaceutical matrices.