Can a wound dressing colour change indicate infection?

wound  dressing

For many years, diagnostic labs have used colour change as a marker for the growth of specific microbes. Think of all those chromogeneic agar plates that your lab goes through each day. And there are all sorts of broths that change colour in response to specific chemical changes caused by microbial growth. One of the first projects I was ever involved with was environmental sampling for MRSA at Lewisham hospital, where we used a selective broth that turned bright yellow when MRSA was present. So in a way, it is surprising that this approach has not been adopted as a marker to indicate wound infection.

Scientists at Bath Uni have developed a neat novel wound dressing that fluoresces when the early signs of an infection are present. The concept is simple: a gel containing tiny sacs of dye are included in a hydrogel dressing; if cytotoxins that are indicative of bacterial infection are present, they lyse the sacs and release the dye, which fluoresces under UV light.

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Biofilms make the hospital environment far from ‘inanimate’


Anybody doubting that biofilms really do exist on dry hospital surfaces needs to read this study: biofilms are there, they are complex, and they are common. A landmark study by the same Australian Vickery group published in 2012 first identified biofilms on a handful of dry hospital surfaces in an ICU. But this study is far more comprehensive and convincing.

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Journal Roundup August 2014: seeking your input

Fist bumpThe August edition of the Journal of Hosptial Infection Journal Roundup is now available, featuring:

  • A whopping five-fold increase in the detection of CRE in 25 US community hospitals.
  • MALDI-TOF as a new frontier for rapid detection of carbapenemase activity.
  • More on fist bumping instead of hand shaking. (Would you like a fist bump greeting from your doctor? No thanks!)
  • Triclosan-impregnated stitches would be cost-effective if they were only a little bit effective, but turns out they’re not effective at all.
  • The new ‘crAssphage bacteriophage’, C. difficile biofilms, and increasing rates of antibiotic resistance – all in the human gut microbiome.
  • Some hope for Ebola drug and vaccine targets.
  • How to reduce the number of sickies that children take from school (through effective school-based immunization programmes).
  • Thoughtful analysis on S. aureus outbreaks of old with lessons for now.
  • Reviews of CRE mortality, global antibiotic use, microbial hitchhikers, overdiagnosis & overtreatment, useless reporting of science in the mainstream media, and whether biocide use drives biocide resistance.

I’ve written three editions of the Journal of Hosptial Infection Roundup now (June, July and August), so there’s a few examples to review. You can read about my methods for producing the Roundup in the blog accompanying the June edition. I thought that now would be a good time to get some feedback, specifically:

  • Is the title right? A few people have expected it to be an overview of articles in the Journal of Hospital Infection only.
  • Is the length about right? (Do you fall asleep reading it or find yourself begging for more?)
  • Is the depth right? Or would you like to read more about less articles, or less about more articles?

Any feedback that you have would be most appreciated. Please either submit a comment below or email me.

Photo credit: ‘Fist bump’.

Do biofilms on dry hospital surfaces change how we think about hospital disinfection?

An important paper published in the Journal of Hospital Infection has identified biofilms on dry hospital surfaces. Biofilms are known to be important in several areas of medicine including indwelling medical devices and endoscope tubing, usually associated with surface-water interfaces. However, it was unclear whether biofilms formed on dry hospital surfaces. The study by Vickery et al. ‘destructively sampled’ several hospital surfaces after cleaning and disinfection using bleach (i.e. cut the materials out of the hospital environment and took them to the lab for analysis). Scanning electron microscopy was used to examine the surfaces for biofilms, which were identified on 5/6 surfaces: a curtain, a blind cord, a plastic door, a wash basin and a reagent bucket. Furthermore, MRSA was identified in the biofilm on three of the surfaces.


Could it be that we have missed or underestimated the importance of biofilms on dry hospital surfaces? Biofilms could explain why vegetative bacteria can survive on dry hospital surfaces for so long, be part of the reason why they are so difficult to remove or inactivate using disinfectants (bacteria in biofilms can be 1000x more difficult to kill than corresponding planktonic bacteria) and explain to some degree the difficulty in recovering environmental pathogens by surface sampling.

Biofilms are clearly not the only reason for failures in hospital disinfection given the difficulty in achieving adequate distribution and contact time using manual methods, but these findings may have implications for infection control practices within hospitals and on the choice of the appropriate disinfectants used to decontaminate surfaces.

Article citation: Vickery K, Deva A, Jacombs A, Allan J, Valente P, Gosbell IB. Presence of biofilm containing viable multiresistant organisms despite terminal cleaning on clinical surfaces in an intensive care unit. J Hosp Infect 2012; 80: 52-55.

Image courtesy of the Lewis Lab at Northeastern University. Image created by Anthony D’Onofrio, William H. Fowle, Eric J. Stewart and Kim Lewis