Introduction. Pseudomonas aeruginosa in healthcare shower waters presents a high risk of infection to immune-suppressed patients; identifying the colonization-status of water outlets is essential in preventing acquisition. Hypothesis/Gap Statement. Testing frequencies may be insufficient to capture presence/absence of contamination in healthcare waters between sampling and remediation activities. Standardization of outlets may facilitate the management and control of P. aeruginosa . Aim. This study aims to monitor shower waters and drains for P. aeruginosa in augmented and non-augmented healthcare settings every 2 weeks for a period of 7 months during remedial actions. Methodology. All shower facilities were standardized to include antimicrobial silver-impregnated showerhead/hose units, hose-length fixed to 0.8 m and replaced every 3 months. Standard hospital manual decontamination/disinfection occurred daily. Thermostatic-mixer-valves (TMVs) were replaced and disinfected if standard remediation unsuccessful. Results. Of 560 shower and drain samples collected over 14 time-points covering 7 months, P. aeruginosa colonized 40 %(4/10; non-augmented) and 80 %(8/10; augmented-care) showers in the first week. For each week elapsed, new outlets became contaminated with P. aeruginosa by 18–19 % (P<0.001) in shower waters (OR=1.19; CI=1.09–1.31) and drains (OR=1.18; CI=1.09–1.30). P. aeruginosa occurrence in shower water was associated with subsequent colonization of the corresponding drain and vice versa (chi-square; P<0.001) with simultaneous contamination present in 31 %(87/280) of areas. TMV replacement was ineffective in eradicating colonisation in ~83 % of a subset (6/20; three per ward) of contaminated showers. Conclusions. We demonstrate the difficulties in eradicating P. aeruginosa from hospital plumbing, particularly when contamination is no longer sporadic. Non-augmented care settings are reservoirs of P. aeruginosa and should not be overlooked in outbreak investigations. Antimicrobial-impregnated materials may be ineffective once colonization with P. aeruginosa is established beyond the hose and head. Reducing hose-length insufficient to prevent cross-contamination from shower drains. P. aeruginosa colonization can be transient in both drain and shower hose/head. Frequent microbiological monitoring suggests testing frequencies following HTM04-01 guidelines are insufficient to capture the colonization-status of healthcare waters between samples. Disinfection/decontamination is recommended to minimize bioburden and the effect of remediation should be verified with microbiological monitoring. Where standard remediation did not remove P. aeruginosa contamination, intensive monitoring supported justifying replacement of showers and contiguous plumbing.

Pseudomonas aeruginosa in healthcare waters presents an infection-risk to immune-suppressed patients. We introduced interventions (quarterly antimicrobial silver-impregnated shower head-hose replacement and shower-hose truncation) to determine effect on presence/persistence of P. aeruginosa in hospital shower-waters and drains over a seven-month survey (560 samples; 14 time-points) on augmented-care (immune-compromised) and non-augmented (general) wards. P. aeruginosa occurrence in the shower or drain predisposed to colonisation of the adjacent site/outlet (chi-square; p<0.001). Up to 80% of shower-waters/drains (augmented-care) were heavily-contaminated (>300CFU) before intervention and persisted despite remediation (P>0.05). Conversely, for every week elapsed, P. aeruginosa in the non-augmented wards increased by ~18% (P<0.001) in shower waters (OR=1.19; CI=1.09-1.31) and drains (OR=1.18; CI=1.09-1.30).Imipenem (showers), and aztreonam/ciprofloxacin-resistance (drains) occurred in up to 75% of sites in augmented-care with cefepime-resistance expressed in the general wards. Resistance-phenotypes declined after remediation despite ciprofloxacin being the only antimicrobial agent prescribed during this period.The shower environment in non-augmented care settings represents unrecognised reservoirs of P. aeruginosa. Once P. aeruginosa-bioburden is established, antimicrobial shower/hose materials and shortening of hoses are ineffective options for remediation. Efficacy-validation of antimicrobial materials and prevention of cross-contamination of the shower environment, plumbing and control-valves is essential to minimise acquisition of P. aeruginosa by vulnerable patients.

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