Survey of healthcare-associated sink infrastructure, and sink trap antibiotic residues and biochemistry, in twenty-nine UK hospitals

Abstract

Background: Hospital sinks are linked to healthcare-associated infections. Antibiotics and chemicals in sink traps can select for pathogens and antimicrobial resistance (AMR). Optimizing sink design and usage can mitigate sink-to-patient dissemination of pathogens.

Aim: To perform a large-scale survey of hospital sink infrastructure.

Methods: Twenty-nine UK hospitals submitted photos and metadata for sinks across three wards (intensive care unit (ICU)/medical/surgical; January-March 2023). Photos were used to classify sink design as 'optimal' according to guidelines and published studies. Sink trap aspirates were dipstick-tested for antibiotics and chemistry. Logistic regression was used to characterize associations of ward type and sink location with optimal sink design or detectable trap antibiotics.

Findings: Of 287 sinks surveyed, 111 were in ICUs, 92 in medical wards, and 84 in surgical wards; 77 were in medicines/drug preparation rooms, 97 on patient bays, 25 in patient side-rooms, and 88 in sluice rooms. Sink-to-bed ratios ranged from 0.23 to 2.83 sinks per patient bed and were higher on ICUs (1.21 versus 0.82 and 0.84 on medical and surgical wards, respectively; P = 0.04). The median sink-to-patient distance was 1.5 m (interquartile range: 1.00-2.21 m). Sink design varied widely; it was deemed 'optimal' for 65/122 (53%) sinks in patient bays/side-rooms and 'optimal' design was associated with side-room location (P = 0.03). Antibiotics were detected in 95/287 (33%) sink traps and were associated with medicines/drug preparation rooms (P <0.001). Sink trap chemicals detected included metals, chlorine, and fluoride.

Conclusion: Sinks are common in hospitals, frequently close to patients, and often sub-optimally designed. Commonly used antibiotics were detected in a third of sink traps and may contribute to the selection of pathogens and AMR in these reservoirs, and subsequent transmission to patients.

Keywords: Antibiotics; Antimicrobial resistance; Hospital-associated infection; Sink design; Sink drains; Sinks.