Contamination of Hospital Plumbing

Abstract

In recent years there have been an increasing number of reports of contamination of hospital plumbing with multidrug-resistant gram-negative organisms, with speculation that this contamination poses a significant risk to patients. 1 Hopman and colleagues 2 add to this body of literature with the report of a patient with a carbapenemase-producing Pseudomonas aeruginosa (CP-PA) infection that was shown to be genetically related to a strain of P aeruginosa from the shower in the patient's room. The patient was a man in his early 60s who had undergone a left-sided pneumonectomy and adjuvant radiotherapy. Subsequent to the procedure, this patient developed a wound infection with a Verona integron-mediated metallo-β-lactamase (VIM)-carrying strain of P aeruginosa. A series of surveillance cultures with negative results for P aeruginosa prior to the patient's infection indicated that his infection was acquired in the hospital. Surveillance culturing of all other patients on the same unit as the case patient failed to uncover any additional patients with positive results for P aeruginosa who might have been the source of his infection. The lack of colonized patients ultimately motivated environmental surveillance to identify potential reservoirs of P aeruginosa in the hospital. Environmental screening revealed CP-PA contamination in the shower drain in the case patient's room, as well as in showers and sinks in adjacent rooms that were connected to a common sewage collection point. The application of whole-genome sequencing (WGS) to patient and environmental isolates supported a single introduction into the hospital seeding both the patient's infection and the contamination of the plumbing. To evaluate the plausibility of airborne transmission from the contaminated shower drain to the patient, the authors evaluated air samples for CP-PA after running the shower for 10 minutes and 15 minutes after the shower had been turned off and found 1 positive result out of several dozen cultures. The hospital ultimately implemented enhanced disinfection of drains, which appeared to eliminate CP-PA from the plumbing. However, on returning to standard disinfection protocols, CP-PA regrowth was observed, which is consistent with findings from other studies that have reported challenges in achieving sustained decontamination of plumbing. 3 A major strength of this work was its use of WGS to demonstrate that environmental contamination across the ward was likely mediated by introduction of P aeruginosa into a single drain. This result highlights how contamination of sink and shower drains can propagate to proximate rooms via plumbing, and illuminates an epidemiologic signature that may be associated with plumbing-mediated outbreaks. However, this study also highlights the challenges in ascertaining the risk that contaminated plumbing poses to patients. In particular, even with a convincing link between the patient and environment provided by WGS, the directionality of the transmission is not evident from the data and analyses provided. A...

Impact of sewer overflow on public health: A comprehensive scientometric analysis and systematic review

“…The top ranked keyword in cluster 3 is "aerosols", which is often underestimated in disease transmission. Aerosolized transmission of pathogens, such as antibiotic-resistant Pseudomonas aeruginosa and Pseudomonas putida, has been reported in previous studies (Gormley et al, 2017;Snitkin, 2019). Likewise, recent studies confirm aerosolized transmission of Covid-19 through air ducts in bathrooms, toilet facilities, and wastewater discharged from WWTPs (Ding et al, 2021;Gholipour et al, 2021;Hwang and Foster, 2008).…”

“…Sanger sequencing (SS) is useful for detection of pathogen mutations and has been utilized in the identification of Covid-19 variant in WWTP and antibiotic-resistant pathogens in plumbing systems (Snitkin, 2019;Westhaus et al, 2021). Compared to SS, genome sequencing (GS) is faster, requires less personnel and less space requirements, and has higher throughput and costeffective.…”

“…Furthermore, recent studies have reported pathogen transmission due to aerolized pathogens and leakages in plumbing systems in hospitals and high-rise buildings (Ding et al, 2021;Gormley et al, 2020;Kotay et al, 2019;Snitkin, 2019;WHO, 2020). Another study also reported sewer overflow into groundwater as a result of faulty sewer pipe joints, sewer leakage, sewer pipe blockage, and poor network repair activities (Yang et al, 2021a).…”

Genomic dissection of endemic carbapenem resistance: metallo-beta-lactamase gene dissemination through clonal, plasmid and integron transfer pathways

“…This propagator pair was able to act as a reservoir of blaIMP-4, likely through occupying an environmental niche as we noted during sampling of ICU sinks. The colonisation of hospital plumbing by CPOs has been well documented 9,[28][29][30][31] , including blaIMP-4harbouring S. marcescens in an Australian setting that was unable to be eradicated 32 . This environmental colonisation enabled not only clonal spread of blaIMP-4 harbouring S. marcescens but also drove diversification through inter-strain transfer of blaIMP-4 IncC plasmids and inter-plasmid transfer of the blaIMP-4 class I integron.…”

Challenges to Long-Accepted Beliefs Encourage Us to Think in New Ways

“…There are studies that have identified the problem with pathogens in the drains of hospital sinks, and multiple solutions have been proposed. A common infection control policy is to flush sink drains with a disinfectant although biofilm regrows after a while (Snitkin, 2019) and some organisms develop drug resistance (Hota et al, 2009). A German study (Doring et al, 1991) of Pseudomonas-Aeruginosa in contaminated sink drains recommended heating the p-trap to kill the microorganisms.…”