Comparison of different disinfection protocols against contamination of ceramic surfaces with Klebsiella pneumoniae biofilm

Protocol group	Protocol No.	Protocol abbreviation	Disinfecting product	Biocidal active substance	Working concentration	Exposure time
A	1	O₃	Ozone generated with a mobile ozone generator	Gaseous ozone	49.914 mg/m³	1 h
A	2	CA	Citric acid	Citric acid	15 %	10 min
A	3	DP1	Disinfecting product 1	1 % benzalkonium chloride	5 % 20 %	10 min
A	4	DP2	Disinfecting product 2	4.8 % benzalkonium chloride 0.1 % 2-phenoxyethanol 0.098 % ethanol 0.05 % glycolic acid 0.02 % N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine	1 %	10 min
B	5	O₃ + 15 % CA	Combined disinfection with gaseous ozone and citric acid (pre-treatment)	Gaseous ozone Citric acid	49.914 mg/m³ O₃ 15 % CA	1 h 10 min
B	6	O₃+ 5 % DP1	Combined disinfection with gaseous ozone and disinfecting product 1 (pre-treatment)	Gaseous ozone 1 % benzalkonium chloride	49.914 mg/m³ 5 % DP1	1 h 10 min
B	7	O₃ + 20 % DP1	Combined disinfection with gaseous ozone and disinfecting product 1 (pre-treatment)	Gaseous ozone 1 % benzalkonium chloride	49.914 mg/m³ 20 % DP1	1 h 10 min
B	8	O₃ + DP2	Combined disinfection with gaseous ozone and disinfecting product 2 (pre-treatment)	Gaseous ozone 4.8 % benzalkonium chloride 0.1 % 2-phenoxyethanol 0.098 % ethanol 0.05 % glycolic acid 0.02 % N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine	49.914 mg/m³ 1 % DP2	1 h 10 min
C	9	15 % CA + O₃	Combined disinfection with citric acid and gaseous ozone (post-treatment)	Citric acid Gaseous ozone	15 % 49.914 mg/m³	10 min 1 h
C	10	5 % DP 1 + O₃	Combined disinfection with disinfecting product 1 and gaseous ozone (post-treatment)	1 % benzalkonium chloride Gaseous ozone	5 % DP1 49.914 mg/m³	10 min 1 h
C	11	20 % DP 1 + O₃	Combined disinfection with disinfecting product 1 and gaseous ozone (post-treatment)	1 % benzalkonium chloride Gaseous ozone	20 % DP1 49.914 mg/m³	10 min 1 h
C	12	DP 2 + O₃	Combined disinfection with disinfecting product 1 and gaseous ozone (post-treatment)	4.8 % benzalkonium chloride 0.1 % 2-phenoxyethanol 0.098 % ethanol 0.05 % glycolic acid 0.02 % N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine Gaseous ozone	1 % DP 2 49.914 mg/m³	10 min 1 h
D	13	15 % CA + O₃ + 20 % DP 1	Combined disinfection with citric acid, gaseous ozone and disinfecting product 1	Citric acid Gaseous ozone 1 % benzalkonium chloride	15 % 49.914 mg/m³20 % DP 1	10 min 1 h 10 min

1 CA – citric acid; DP 1 – disinfection product 1; DP 2 – disinfection product 2; O₃ – ozone

Table 2

Average log₁₀ CFU reduction ranks of disinfection protocol groups against K. pneumoniae ATCC 700603

Protocol group	Average rank	Median	Disinfectant	Median	SE
A (single biocidal active substance)	2.000	1.743^a	O₃	2.689^A	0.065
			15 % CA	1.665^B	0.142
			20 % DP1	1.865^B	0.152
			1 % DP2	1.438^B	0.168
B (combined biocidal active substance)	2.583	3.161^b	O₃ + 15 % CA	4.161^A	0.476
			O₃ + 5 % DP1	3.113^B	0.079
			O₃ + 20 % DP1	5.255^A	0.019
			O₃ + 1 % DP2	1.945^C	0.229
C (combined biocidal active substance)	2.750	5.078^b	15 % CA + O₃	5.190^A	0.083
			5 % DP1 + O₃	4.929^A	0.073
			20 % DP1 + O₃	5.190^A	0.031
			1 % DP2 + O₃	2.088^B	0.159
D (combined biocidal active substance)	3.667	5.290^c	CA + O₃ + 20 % DP1	5.290	0.024

1 CA – citric acid; DP 1 – disinfection product 1; DP 2 – disinfection product 2; O₃ – ozone; SE – standard error. Different lowercase letters in superscript indicate statistically significant difference between groups (P<0.05). Different uppercase letters in superscript indicate statistically significant difference between biocidal substances used in protocol (P<0.05)

Table 3

Average log log CFU reduction ranks of disinfection protocol groups against K. pneumoniae 14

Protocol group	Average rank	Median	Disinfectant	Median	SE
A (single biocidal active substance)	1.000	1.761^a	O₃	1.628	0.131
			15 % CA	1.707	0.143
			20 % DP1	1.889	0.140
			1 % DP2	1.673	0.143
B (combined biocidal active substance)	2.500	3.663^b	O₃ + 15 % CA	5.128^A	0.122
			O₃ + 5 % DP1	2.415^B	0.131
			O₃ + 20 % DP1	4.929^A	0.078
			O₃ + 1 % DP2	2.184^B	0.129
C (combined biocidal active substance)	2.667	4.923^b	15 % CA + O₃	5.124^A	0.053
			5 % DP1 + O₃	4.801^A	0.135
			20 % DP1 + O₃	5.127^A	0.124
			1 % DP2 + O₃	1.938^B	0.084
D (combined biocidal active substance)	3.833	5.699^c	CA + O₃ + 20 % DP1	5.699	0.098

1 CA – citric acid; DP 1 – disinfection product 1; DP 2 – disinfection product 2; O₃– ozone; SE – standard error. Different lowercase letters in superscript indicate statistically significant difference between groups (P<0.05). Different uppercase letters in superscript indicate statistically significant difference between biocidal substances used in protocol (P<0.05)

Representative 3D images of *K. pneumoniae* biofilm on ceramic tiles treated with different single and combined disinfection protocols using digital microscopy according to disinfection efficacy (20× magnification); 1 – O₃; 5 – O₃+ 15 % CA; 9 – CA + O₃; 11 – 20 % DP1 + O₃; 7 – O₃ + 20 % DP1; 13 – CA + O₃ + 20 % DP1; CN – control (no treatment); CA – citric acid; DP 1 – disinfection product 1; DP 2 – disinfection product 2; O₃– ozone

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DOI: https://doi.org/10.2478/aiht-2024-75-3920 | Journal eISSN: 1848-6312 (formerly 0004-1254) | Journal ISSN: 0004-1254

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Language: English, Croatian

Page range: 289 - 296

Submitted on: Nov 1, 2024

Accepted on: Dec 1, 2024

Published on: Dec 29, 2024

Published by: Institute for Medical Research and Occupational Health

In partnership with: Paradigm Publishing Services

Keywords:

benzalkonium chloride,

Related subjects:

Basic medical science,

Basic medical science, other

© 2024 Kaća Piletić, Silvestar Mežnarić, Eli Keržić, Martina Oder, Ivana Gobin, published by Institute for Medical Research and Occupational Health
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 75 (2024): Issue 4 (December 2024)

Comparison of different disinfection protocols against contamination of ceramic surfaces with Klebsiella pneumoniae biofilm

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