Post-Outbreak Investigation of Pseudomonas aeruginosa Faucet Contamination by Quantitative Polymerase Chain Reaction and Environmental Factors Affecting Positivity

Abstract

OBJECTIVETo perform a post-outbreak prospective study of the Pseudomonas aeruginosa contamination at the faucets (water, aerator and drain) by culture and quantitative polymerase chain reaction (qPCR) and to assess environmental factors influencing occurrenceSETTINGA 450-bed pediatric university hospital in Montreal, CanadaMETHODSWater, aerator swab, and drain swab samples were collected from faucets and analyzed by culture and qPCR for the post-outbreak investigation. Water microbial and physicochemical parameters were measured, and a detailed characterization of the sink environmental and design parameters was performed.RESULTSThe outbreak genotyping investigation identified drains and aerators as the source of infection. The implementation of corrective measures was effective, but post-outbreak sampling using qPCR revealed 50% positivity for P. aeruginosa remaining in the water compared with 7% by culture. P. aeruginosa was recovered in the water, the aerator, and the drain in 21% of sinks. Drain alignment vs the faucet and water microbial quality were significant factors associated with water positivity, whereas P. aeruginosa load in the water was an average of 2 log higher for faucets with a positive aerator.CONCLUSIONSP. aeruginosa contamination in various components of sink environments was still detected several years after the resolution of an outbreak in a pediatric university hospital. Although contamination is often not detectable in water samples by culture, P. aeruginosa is present and can recover its culturability under favorable conditions. The importance of having clear maintenance protocols for water systems, including the drainage components, is highlighted.Infect. Control Hosp. Epidemiol. 2015;36(11):1283–1291

Prolonged outbreak of clonal MDR Pseudomonas aeruginosa on an intensive care unit: contaminated sinks and contamination of ultra-filtrate bags as possible route of transmission?

“…Contaminated sinks or faucets have been described as sources for P. aeruginosa outbreaks in the past [1, 2, 4, 11, 19, 20]. In many outbreaks, contaminated washbasins served as continuous sources.…”

“…This is supported by the finding that antimicrobial therapy prior to an ICU stay increases the risk for colonization with MDR P. aeruginosa [8, 15] . Once the organisms are introduced into an ICU, they can cause outbreaks that are often associated with sinks or faucets as a continuous source of further spread [1, 2, 11, 19, 20]. However, the most likely transmission route is direct person-to-person contact [10].…”

Methodological approaches for monitoring opportunistic pathogens in premise plumbing: A review

“…It has been extensively applied for OPPP monitoring for both environmental and clinical samples (Adrados et al, 2011; Ahmed et al, 2014; Bedard et al, 2015; Behets et al, 2007a; Beumer et al, 2010; Bonetta et al, 2010; Madarova et al, 2010; Morio et al, 2008; Qin et al, 2003; Radomski et al, 2010). Given its consistency and quantitative capabilities, q-PCR has potential to be accepted as a standard method for pathogen monitoring.…”

“…Head-to-head comparison of OPPP detection by q-PCR and culture of water and biofilm samples has been the subject of multiple studies (Table 2), with the general trend being higher detection frequency and cell numbers by q-PCR (e.g., Legionella (Wang et al, 2012; Wellinghausen et al, 2001; Wullings et al, 2011), mycobacteria (Hussein et al, 2009; Radomski et al, 2013), P. aeruginosa (Bedard et al, 2015), N. fowleri (Behets et al, 2007a)). This phenomenon is likely associated with higher sensitivity and lower detection limit of q-PCR.…”

The role of hospital environment in transmissions of multidrug-resistant gram-negative organisms

“…When sink basin drainage was immediately underneath the faucet, environmental contamination occurred regardless of the speed of the drainage but was 8 times greater with slow drainage. The importance of sink basin design was supported by a separate study, where sinks with faucets aligned behind a drain had a higher rate of contamination by P. aeruginosa compared to drains aligned directly with, in front of, or to the side of the faucet [33]. Similarly, slower drainage was found to be associated with a higher microbiological burden and drain positivity for contamination [33].…”