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Bacterial recolonization of hospital sink biofilms
H G Healy1, E Pawluk2, L Dieter3
1Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA; Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Yale Institute for Biospheric Studies, Yale University, New Haven, CT, USA.
Background:
Hospital sink drains are known reservoirs for many pathogens that cause healthcare-associated infections (HAIs). Drain bacteria can migrate up to the drain cover and then spread to surrounding surfaces and patients through droplet dispersal during sink use. Therefore, cleaning sink surfaces represents a key intervention strategy to limit transmission between drains and patients.
Aims:
In this study, we aimed to: (1) characterize microbial community taxonomy and abundance in sink components and (2) evaluate the kinetics and sources of bacterial recolonization onto sink surfaces after cleaning.
Methods:
Drainpipes, drain covers, sink basins, drinking water, and p-trap liquid from hospital sinks in New Haven, CT, USA were sampled before and after intervention surface cleaning/disinfection (N = 251). Bacterial abundance and taxonomy were assessed via culture counts, digital droplet PCR, MALDI-ToF, and 16S rRNA gene amplicon sequencing.
Findings:
Drain biofilms had median bacterial abundance of 1.80 × 108 16S rRNA gene copies/cm2 and 2.06 × 106 cfu/cm2, which correlated with bacterial abundance on sink surfaces. Hallway sinks, which were used more frequently than patient room sinks, had higher bacterial abundance. Drain microbial communities largely consisted of novosphingobium and sphingobium, with detection of acinetobacter, pseudomonas, legionella, and stenotrophomonas. Sink surfaces had abundant mycobacterium, methylobacterium-methylorubrum, and sphingobium, as well as genera common to skin microbiomes (e.g., corynebacterium, staphylococcus, streptococcus). Immediately after cleaning/disinfection, culturable bacteria were generally undetectable on drain covers; bacterial gene copies were reduced but rebounded to over 80% of pre-cleaning levels within 24 h. After seven days, 9.2% of recolonizing bacteria were derived from drains, and 15.7% were from tap water.
Conclusion:
This study contributes to our understanding of factors that influence pathogen abundance on hospital sink surfaces and limitations of routine cleaning and disinfection.
Insights
Hospital sink drains harbor pathogens that cause healthcare-associated infections (HAIs). Routine cleaning limits, but does not eliminate, bacterial recolonization from drains and water within 24 hours.
Area of Science:
- Environmental microbiology
- Infection control
- Hospital hygiene
Background:
- Hospital sink drains are significant reservoirs for pathogens contributing to healthcare-associated infections (HAIs).
- Bacteria from drains can spread to surfaces and patients via droplet dispersal during sink use.
- Effective cleaning of sink surfaces is crucial for limiting pathogen transmission.
Purpose of the Study:
- Characterize the microbial community composition and abundance within hospital sink components.
- Evaluate the rate and primary sources of bacterial regrowth on sink surfaces post-cleaning.
Main Methods:
- Collected samples from drainpipes, covers, basins, drinking water, and p-trap liquid from 251 hospital sinks.
- Assessed bacterial abundance and taxonomy using culture counts, digital droplet PCR, MALDI-ToF, and 16S rRNA gene sequencing.
- Analyzed microbial communities before and after surface cleaning and disinfection.
Main Results:
- Drain biofilms showed high bacterial abundance (median 1.80 × 10^8 16S rRNA gene copies/cm^2).
- Bacterial levels on sink surfaces correlated with drain biofilm abundance; hallway sinks had higher counts than patient room sinks.
- After cleaning, bacteria rebounded to over 80% of pre-cleaning levels within 24 hours, with drains and tap water as significant recolonization sources.
Conclusions:
- Hospital sink surfaces are rapidly recolonized after cleaning, highlighting limitations of routine disinfection protocols.
- Understanding drain and water contributions is key to improving infection control strategies.
- Further research is needed to develop more effective interventions against sink-associated HAIs.
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