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.