Microbiological validation of a 0.25% quaternary ammonium surface disinfectant using the dilution-neutralisation method

Pairazamano A.T.E.; Pinto J.D.C.; Cárdenas V.L.E.; Alvarado E.O.; Chavez J.R.; Justiniano C.G.B.; Marquez N.O.Q.; Villalobos D.R.R. · Journal of Pharmacy and Pharmacognosy Research (2026) · DOI: 10.56499/jppres_14.1.2205

Resumen

Context: The validation of microbiological methods in medical devices is key to ensuring patient safety and the efficacy of healthcare products. These types of studies respond to the need to comply with international regulatory requirements and ensure the quality of analytical techniques. Aims: To validate the analytical technique of microbial count by dilution-neutralisation of 0.25% quaternary ammonium. Methods: Deductive, applied, quantitative and experimental, method, consisting of six batches of three samples with different percentages of cake enriched with oyster mushroom (Pleurotus ostreatus) and 30 panelists of different ages and genders where a checklist was applied for data collection. Results: The results obtained count lower than 100 CFU for the strains Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Candida albicans ATCC 10231, and Aspergillus brasiliensis ATCC 16404. The proficiency test successfully recovered all the test microorganisms in the 10-2 dilution, presenting growth and identification of specific microorganisms. Validation of the neutralisation method showed adequate efficacy of the neutraliser at the 10-2 dilution and demonstrated the absence of toxicity of the neutraliser. The accuracy of the recovery percentages was within the 90% confidence interval, the precision of the test was <15% of the coefficient of variation, and it was demonstrated that the neutralisers used were specific to inhibit the antimicrobial properties of quaternary ammonium. The limit of detection recovered Pseudomonas aeruginosa >11 CFU and Staphylococcus aureus >17 CFU, robustness demonstrated that there was no significant variability in the counts, at different incubation times. Conclusions: The dilution method - neutralisation with soy lecithin 0.5% and polysorbate 80 4%, allowed the recovery of the test microorganisms at the 10-2 dilution. © (2026), (Academic Association of Pharmaceutical Sciences from Antofagasta (ASOCIFA)). All right reserved.

Instituciones: Universidad Peruana Cayetano Heredia; Universidad Privada Norbert Wiener; Universidad Católica de Trujillo Benedicto XVI