Intended for healthcare professionals

Feature Christmas 2023: Champagne Problems

Bug in a mug: are hospital coffee machines transmitting pathogens?

BMJ 2023; 383 doi: (Published 18 December 2023) Cite this as: BMJ 2023;383:p2564
  1. Sarah Victoria Walker1 2,
  2. Alessa Lalinka Boschert2,
  3. Martina Wolke2,
  4. Wolfgang A Wetsch34
  1. 1RKH Regionale Kliniken Holding und Services GmbH, Institute for Clinical Microbiology and Hospital Hygiene, Ludwigsburg, Germany
  2. 2Institute for Medical Microbiology, Immunology and Hygiene, University Hospital Cologne
  3. 3Faculty of Medicine, University of Cologne
  4. 4Anaesthesiology and Intensive Care Medicine, University Hospital of Cologne
  1. Correspondence to: sarah.walker{at}

For many, coffee is the elixir of life. But is it also a cradle of life?Sarah Victoria Walker and colleaguespeer into the depths of the hospital coffee machine

Coffee is an easily available stimulant that sustains the workforce. Healthcare workers in particular are renowned for their coffee dependence, and the coffee machines found in break rooms or at employees’ home are well used—and regularly touched by bare hands.

The World Health Organization recommends eliminating any potential vector in the transmission of nosocomial infections, and the search for hazards within hospitals is ongoing. Various personal objects, and doctors’ attire, have been investigated as transmission sources for pathogenic bacteria, notably leading to the nationwide ban on wearing ties in UK hospitals (limited data on contamination with meticillin resistant Staphylococcus aureus led to their classification as a potential hazard).1 Even hospital Bibles have been examined, although not (yet) deemed abolishable.23

What, then, of the coffee maker? Pathogenic, multiresistant species have been detected in household appliances such as dishwashers that are typically located in the kitchen.4 And the hands of hospital staff are a known source of spreading pathogens with the accompanying risks for nosocomial outbreaks, increased morbidity and mortality, and the financial burden on healthcare system5 (hands can’t yet be eliminated without severely hampering staff—so handwashing, gloves, and instruments must suffice for now).

While the microbiome of coffee machines in general has already been described,6 their potential as a source of nosocomial pathogens has not been explored. Until now.

By whatever beans necessary

We assessed the microbial population in healthcare associated coffee machines, …

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