INFECTION CONTROL
Multidrug-resistant gram-negative bacteria
According to the WHO, antimicrobial resistance (AMR) represents a growing threat to global health – one that is placing populations at heightened risk. Paul Owen, global business unit manager – healthcare & life sciences at Mueller Europe, discusses how built environment strategic planning and estates teams can help to manage this growing crisis.
The World Health Organization (WHO) has made its position unmistakably clear. Multidrug- resistant gram- negative bacteria are no longer an emerging concern but a dominant global health threat, with carbapenem resistance representing one of the most critical failures in contemporary antimicrobial therapy. Organisms once treatable with last line of defence
drugs such as meropenem and imipenem are now demonstrating sustained resistance across healthcare systems worldwide. Cefiderocol (Fetcroja) – a new cephalosporin
developed to be active against carbapenem resistant bacteria – was only approved for use in the EU in April 2020 and there are already studies suggesting that high rates of resistance in Cefiderocol are already being tracked. From carbapenem resistant Klebsiella pneumoniae and Enterobacterales to highly resistant Acinetobacter baumannii and Pseudomonas aeruginosa, the organisms shaping the modern antimicrobial resistance landscape are increasingly defined by their ability to survive even the most advanced antibiotic intervention. The implications extend far beyond pharmacology. As therapeutic options contract, the global response is shifting toward prevention, containment, and environmental control. The WHO now frames the fight against carbapenem resistance not simply as a drug development challenge, but as a systems level priority requiring coordinated clinical, microbiological and infrastructure-based action. The shift from clinical responsibility and a sustainable policy on antibiotic management has now tangibly expanded to include built environmental management.
Favourable ecological conditions Moist plumbing environments provide highly favourable ecological conditions for the persistence and amplification of gram-negative bacteria. Drains, sinks, and basins function not simply as passive waste pathways but as active microbial reservoirs capable of sustaining complex, structured communities over prolonged periods. Several environmental characteristics make these sites particularly conducive to colonisation.
n Continuous moisture availability Gram-negative organisms require hydrated environments for survival and metabolic activity. Plumbing systems maintain persistent dampness, often with intermittent stagnation that allows organisms to establish stable populations.
n Nutrient accumulation Organic matter from handwashing, clinical waste fluids, skin debris, food residues, and pharmaceutical compounds accumulates within pipework and trap systems. This provides a continuous nutrient supply that supports microbial growth and diversification.
n Temperature stability Ambient and lukewarm water conditions common in healthcare plumbing systems fall within optimal growth ranges for many gram-negative species, enabling continuous replication.
n Low mechanical disturbance in key zones U-bends, trap seals and horizontal pipe segments create areas of reduced flow where microorganisms can accumulate without regular flushing.
n Aerosol generation and splash dispersion Water impact within contaminated drains can generate droplets and aerosols containing viable organisms. These may contaminate surrounding surfaces, equipment, and hands, creating transmission pathways into the clinical environment.
n Antimicrobial exposure gradients Sublethal concentrations of cleaning agents, disinfectants, and residual antibiotics can accumulate within wastewater, creating selective pressure that favours resistant strains, including carbapenem resistant organisms.
n Operational significance Drains and sink systems therefore act as persistent
June 2026 Health Estate Journal 31
Klebsiella pneumoniae.
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