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Friday, May 31, 2013

Can I borrow your pen?

A study I recently came across by Halten et al of the University of Houston investigated the potential of writing pens as a source of transmission, which could be significant for hospital infection control practices when you consider the ubiquity of the instruments in healthcare facilities.  As this is tradeshow season where sharing of pens is a virtual second by second occurrence, I was curious to find out just how contaminated pens could get.

For the study, the clinical investigators responsible for enrolling patients into a study investigating antibiotic associated diarrhea were given a new writing pen each day.  They were then randomly assigned each day to clean the pen between patient visits while the non-intervention group did not clean the pens. After using the pen for the entire day to enroll patients, the investigators put the pen in a sterile labeled bag.  The pens were then immediately transported to the laboratory. Four unused writing pens were used as controls to assure that pens were not previously contaminated with microorganisms.

Unfortunately the sample size in the study was quite small, just 23 pens (10 in the intervention group, and 13 in the non-intervention group), in addition to the four control pens. For each group, between 2 and 11 patients touched each pen, along with the assigned investigator.  In the non-intervention group 12 of 13 pens showed bacterial growth compared with 4 of 10 pens in the intervention group. No growth was observed on control pens.

No Gram-negative bacilli, such as Pseudomonas spp.or E. coli, were identified in either group, which tells me that the investigators were being fastidious hand washers at least for the duration of the test.  There was however a significant difference in the Gram-positive cocci, presumptively identified as Staphylococcus spp. and Enterococcus spp. in the intervention compared with the non-intervention group.

The study showed that cleaning/sanitizing the pens can significantly reduce the level of potential pathogenic bacteria.  This is an important finding indicating that the risk of transmission of healthcare-associated pathogens can be decreased with the use of a sanitizing agent for wiping fomites such as writing pens between patients.  The ability of bacteria to survive on pens for long durations of time emphasizes the need to clean equipment (i.e. pens) after patient contact.

Seeing as I head to the CHICA-Canada conference this Sunday, I think perhaps I'll pack extra pens and be sure NOT to share mine.  I have a nasty habit of putting my pen in my mouth and I can't trust that everyone will be as fastidious in their hand washing as the clinical investigators in this study....

Hasta la vista!


aka “The Germinator”


  1. when everybody should be aware of the rules and would obey them, they would disinfect their hands after and before patient-contact.
    To put it boldly, the pen may be as contaminated as the toilet-bowl but the disinfection step takes care of it.
    The fact that we worry about contaminated pens shows that handdisinfection isn't general practice

  2. Very well said Henk! If our hand hygiene compliance was 100%, it wouldn't matter if the pen was contaminated because we would always wash our hands after touching it and prior to patient contact. Unfortunately, that's not reality. Therefore the combination of environmental cleaning and hand hygiene is absolutely necessary.