Commercial Disinfectants During Disinfection Process Validation: More Failures than Success

Abstract

Introduction: Disinfection process validation is mandatory before introduction of a new disinfectant in hospital services. Commercial disinfection brands often question existing hospital policy claiming greater efficacy and lack of toxicity of their products. Inadvertent inadequate disinfection leads to morbidity, patient's economic burden, and the risk of mortality.

Aim: To evaluate commercial disinfectants for high, intermediate and low-level disinfection so as to identify utility for our routine situations.

Materials and methods: This laboratory based experiment was conducted at St Stephen Hospital, Delhi during July-September 2013. Twelve commercial disinfectants: Sanidex®, Sanocid®, Cidex®, SekuSept Aktiv®, BIB Forte®, Alprojet W®, Desnet®, Sanihygiene®, Incidin®, D125®, Lonzagard®, and Glutishield® were tested. Time-kill assay (suspension test) was performed against six indicator bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella Typhi, Bacillus cereus, and Mycobacterium fortuitum). Low and high inoculum (final concentrations 1.5X10(6) and 9X10(6) cfu/ml) of the first five bacteria while only low level of M. fortuitum was tested.

Results: Cidex® (2.4% Glutaraldehyde) performed best as high level disinfectant while newer quarternary ammonium compounds (QACs) (Incidin®, D125®, and Lonzagard®) were good at low level disinfection. Sanidex® (0.55% Ortho-pthalaldehyde) though mycobactericidal took 10 minutes for sporicidal activity. Older QAC containing BIB Forte® and Desnet® took 20 minutes to fully inhibit P. aeruginosa. All disinfectants effectively reduced S. Typhi to zero counts within 5 minutes.

Conclusion: Cidex® is a good high-level disinfectant while newer QACs (Incidin®, D125®, and Lonzagard®) were capable low-level disinfectants.

Keywords: Bacillus cereus; Glutaraldehyde; High level disinfection; Mycobactericidal; Time Kill Assay.

[Table/Fig-2]:

Log10 (colony forming units/ml) reduction in bacterial growth (both high and low inoculums) at various exposure points with aldehyde (D1, D3, D12) and oxidizing agent (D4, D6) groups of disinfectants. A: Aldehydes: D1 (Sanidex®), D3 (Cidex®), and D12(Glutishield®) as High-level disinfectant. B:Oxidizing Agents: D4 (Seku Sept Aktive®) and D6 (Alprojet W®) as High-level disinfectant. C: Aldehydes: D1, D3, and D12 as Intermediate-level disinfectant. D: Oxidizing Agents: D4 and D6 as Intermediate-level disinfectant. E: Aldehydes as low level disinfection (all four bacteria E. coli, S. aureus, S. Typhi and P. aeruginosa showed zero growth at 5 minutes and beyond hence not shown separately). F: Oxidizing Agents: D4 and D6 as Low-level disinfectant. Inoc = Inoculum

[Table/Fig-3]:

Log10 (colony forming units/ml) reduction in bacterial growth (both high and low inoculums) at various exposure points with Quarternary Ammonium compund (D5, D7, D9, D10, D11) and combination (D2, D8) groups of disinfectants. A: Quarternary Ammonium Compunds: D5 (BIB-Forte®), D7(Desnet®), D9 (Incidin®), D10 (D125®), D11 (Lonzagard®) as High-level disinfectant. B: Quarternary Ammonium Compunds: D5, D7, D9, D10, D11 as Intermediate-level disinfectant. C: Quarternary Ammonium Compunds: D5, D7, D9, D10, D11 as Low-Level disinfectant (against Pseudomonas aeruginosa only; against Staphylococcus aureus, Salmonella Typhi and Escherichia coli zero counts were recorded for all disinfectants at 5 minutes and beyond). D: Combination disinfectants: D2 (Sanocid®) and D8 (Sanihygiene®) as High-level disinfectant and as Intermediate-Level disinfectant. (both D2 and D8 as low level-disinfectant, reduced S. aureus, E. coli, S. Typhi and P. aeruginosa to zero counts at 5 minutes and beyond, hence not shown in figure). Inoc = Inoculum