974 Table 1. (Continued )


Reference 15


Outbreak Organism MβL Pa


Drain Type (% Positive)


44 sinks positive for ObS


16 17 ESBL Ko MDR Pa


Sinks 11/56 (20) Showers 1/19 (5.2)


Sink 4/4 (100%)


Longest Interval Between Cases


Duration of Outbreak before first direct WWD Intervention Initial Interventions (months)


20 mo 50 mo BIPI (49 mo)


Philip C. Carling


Subsequent Interventions


1. EIPI 2. Sink drain replacement decreased but did not eliminate outbreak strain.


11 mo 12 mo EIPI (11 mo) 5 mo 7 mo BIPI (10 mo) Sinks replaced


1. EIPI 2. Sink drain systems replaced; 1 patient became colonized with ObS in 6 mo follow-up.


18 ESBL Ec


17 Sinks and “many” showers


19 MβL Pa Sinks 12/12 (100) 4 mo


21 mo EIPI revealed that all isolates were resistant to QAC (14 mo).


7 mo


61 mo Sink replacement but 3/11 recolonized “on average” 13 weeks later. Drains positive after 10 weeks of acetic acid treatment protocol


20 21 22 23 ESBL Ec MβL Pa MβL Ec


Multiple species sharing resistance genes including MβL


24


2 strains of MDR in P-traps


Sinks Sinks 11/24 (46) Sink 1/1 (100) Sinks 32/32 (100) N/A 1 mo EIPI (3 mo) 40 mo 84 mo 1. EIPI (80 mo) N/A N/A


<1 mo 1. EIPI 2. Bleach treatment protocol (9 mo)


N/A


1. EIPI 2. After daily treatment with glucoprotamin for 4 mo. 9/32 (28%) remained positive.


Sink P-traps 149/437 (34)


24 mo 30 mo All sinks replaced but recolonization with ObSs was confirmed.


1. “Biofilm removal” 2. Daily bleach protocol decreased incidence of OS infection


Weekly acetic acid treatment protocol continued but did not eliminate OSB contamination.


1. ICU closed 2 . Sinks replaced. “Increased incidence rate has decreased.”


1. Sink drain replacement 2. Unit Closed and rebuilt


Single sink system replaced Sink system replaced


1. Twice weekly bleach treatment


2. P-trap replacement for patient stay >7 days


3. Outcome: ongoing recontamination but no new patient acquisition for 36 mo.


NOTE. CRE, carbapenem-resistant Enterobacteriaceae; Ec, Escherchia coli; ESBL, extended-spectrum β-lactamase; Ko, Klebsiella oxytoca; Kp, Klebsiella pneumoniae; KPC, Klebsiella pneu- moniae carbapenemase; MβL, metallo-β-lactamase; MDR, multidrug resistant; Ab, Acinetobacter; N/A, not available; ObS, outbreak strain; Pa, Pseudomonas aeruginosa; WWD, wastewater drains; BIPI, basic infection prevention interventions; CHG, chlorhexidine gluconate; EIPI, enhanced infection prevention interventions; N/A, not available; ObS, outbreak strain; QAC, quaternary ammonium compound.


units (ICUs) and 1 burn treatment unit and were reported in Europe (n=5), Australia (n=1), Thailand (n=1), and Japan (n=1). Aside from the 5 studies in which only 1 sink drain was cul-


tured, 12 studies reported culturing samples from between 1 and 910 WWDs as part of a preintervention outbreak analysis (Table 1).3,5,11,22 The proportion of positive WWDs ranged between 16% and 100% (mean, 60%). As part of evaluations prior to performingWWDcultures, 15 sites performed several hundred environmental cultures of dry patient-zone surfaces, including sink bowls and sink surrounds. The results of these cultures revealed that these sites were rarely positive for ObS organisms (<1%). In each of the 9 studies identifying Pseudomonas as the outbreak CRO, sink water taps were excluded as a source of the


outbreak. Various systems for genotypic testing were employed to define clonality in 13 studies (56%), and in 10 studies, pulse-field gel electrophoresis was used (primarily before 2013).


Epidemiologic features


Of the 23 outbreaks reviewed here, 3 (13%) were relatively short(ie,1,4,and 6monthsinduration),which precludedthe evaluation of their timelines. The study durations of the other 20 outbreaks ranged from 7 to 96 months (mean 37 months), with 14 (70%) lasting 2 or more years. A total of 344 patients (range, 1–84; median, 15 per study) were either colonized or infected with outbreak strains. (Patients identified by screening


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