Pseudomonas aeruginosa, a water-associated opportunistic pathogen, can be isolated from a variety of environments including soil and water. It is extremely adaptable and survives and best grows in moist environments including showerheads, shower hoses, tap outlets, valves, expansion vessels, medical devices in contact with water and soap used for hand washing. Pseudomonas aeruginosa poses an infection risk, especially for humans with immunosuppressive conditions, open wounds and catheter entering sites. Due to their tendency to quickly develop antibiotic resistencies, Pseudomonas aeruginosa infections are often difficult to treat and can become lethal.
How does Pseudomonas aeruginosa contaminate soap dispensers?
Refillable soap dispensers are often a source of Pseudomonas aeruginosa contamination, along with other gram-negative bacteria. Microorganisms can enter the soap through improper refilling practices and insufficient cleaning of the dispensers. Contaminations of liquid soaps with up to 8 CFU/g liquid soap have been described.1 Next to the soap, components like the pump mechanism can also serve as bacterial reservoirs and compromise hand hygiene: instead of reducing bacterial loads, the use of contaminated soap may increase bacterial contamination on hands and contribute to further transmission of Pseudomonas aeruginosa to devices and patients. 2
Hat kontaminierte Seife jemals Infektionen mit Pseudomonas aeruginosa verursacht?
In 2007, two oncohematology patients died from confirmed systemic infections caused by Pseudomonas aeruginosa strains in a newly built Italian hospital. Extended environmental investigation and typing revealed the presence of 5 different strains across several soap dispensers, including the dispenser in the nurse station, where drugs and medical devices were also stored. The specific soap dispenser harbored 5 x 104 CFU/ml Pseudomonas aeruginosa and showed the same phenotypic traits as all clinical isolates, making it a highly probable continuous source of infection. Additionally, a good evidence of association between infections and duration of central venous catheter (CVC) was found, suggesting that CVC handling by transiently contaminated healthcare workers could have played a role in the spreading of Pseudomonas aeruginosa.3 Further cases of clonal similarity and/or identity between contaminated soap with Pseudomonas aeruginosa and infected patient materials have been described.4
Best practices for contamination and infection control
As Pseudomonas aeruginosa has low nutrient requirements and can therefore thrive under most circumstances, introduction of adequate control measures to either stop the transmission or eliminate the contamination source is essential to minimize infection risk. The use of alcohol-based hand sanitizers, regular maintenance, and cleaning of soap dispensers, and switching to sealed soap dispensers are recommended to significantly reduce contamination and infection risks and ensure patient safety.2,3 Effective management of Pseudomonas aeruginosa in in-premise water systems requires expertise, focus and continuous effort by Water Safety Groups and implementation of accurate Water Safety Plans.
References:
[1]: Blanc, D. S. et al., „Hand soap contamination by Pseudomonas aeruginosa in a tertiary care hospital: No evidence of impact on patients”, J Hosp Infect, 93(1), 63–67, 2016
[2]: Lucassen, R. et al., “A loophole in soap dispensers mediates contamination with Gram-negative bacteria”, MicrobiologyOpen, 12(5), e1384, 2023
[3]: Lanini S. et al., “Molecular Epidemiology of a Pseudomonas aeruginosa Hospital Outbreak Driven by a Contaminated Disinfectant-Soap Dispenser”, Plos One, 6(2), e17064, 2011
[4]: Fanci R et al., “Molecular epidemiological investigation of an outbreak of Pseudomonas aeruginosa infection in an SCT unit”, Bone Marrow Transplant, 43(4), 335-8, 2009
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