Abstract
Purpose:
To compare antimicrobial efficacy of multipurpose disinfecting solutions (MPS) against combined inoculum of ISO bacteria and Gram-negative clinical isolates during 14 days storage.
Methods:
The multipurpose disinfecting solutions studied were - MPS-1: polyquaternium (PQ1)+alexidine dihydrochloride (ALX), MPS-2: polyhexamethylene biguanide (PHMB)+poloxamer, MPS-3: PQ1+myristamidopropyl dimethylamine (ALDOX)+nonanoyl-EDTA, MPS-4: PQ1+ALDOX+polyoxyethylene-polyoxybutylene (EOBO-41), MPS-5: PQ1+ALDOX and MPS-6: PHMB+PQ1. Test solutions were inoculated with combined inoculum of ISO bacteria and Gram-negative clinical isolates in the test tube according to ISO 14729. Test solution efficacy was evaluated at minimum recommended manufacturer disinfection time of 6 hours, 24 hours, 7 days and 14 days. ISO bacteria tested were: Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 9027 and Serratia marcescens ATCC 13880. Clinical isolates tested were: Achromobacter sp., Serratia marcescens and Achromobacter xylosoxidans.
Results:
After 6 hours exposure, MPS-1, MPS-2 and MPS-6 showed >2.4 log kill against combined inoculum of all ISO bacteria and clinical isolates and did not exhibit reduced efficacy or regrowth over 14 days. MPS-3 showed <1 log kill against combined inoculum of all ISO bacteria and clinical isolates after 6 hours exposure, and exhibited regrowth over 14 days. MPS-4 and MPS-5 exhibited <1 log kill against combined inoculum of all ISO bacteria and Serratia marcescens and all ISO bacteria and Achromobacter xylosoxidans clinical isolates after 6 hours exposure and showed reduced efficacy over 7 days storage. MPS-4 and MPS-5 exhibited <1.5 log kill against combined inoculum of all ISO bacteria and Achromobacter sp. clinical isolate after 6 hours exposure and showed reduced efficacy after 24 hours. Low numbers of ISO bacteria S. aureus and S. marcescens were observed for MPS-3, MPS-4 and MPS-5 after 6 hours exposure when combined inoculum of these bacteria and Achromobacter sp. was used.
Conclusions:
MPS-1, MPS-2 and MPS-6 showed high ability to reduce microbial load after 14 days storage, while MPS-4 and MPS-5 exhibited reduced disinfection efficacy. MPS-3 exhibited low disinfection efficacy at 6 hours and regrowth over 14 days.