Building the CDC in your community

I am not referring here to the Centre for Disease Control, which is a great resource which I use often to look up things I should know anyway, but don’t.

I am referring to the acronym “Clinical Details Culture”, an equally important CDC in my mind.

At the laboratory I work in, we have just implemented a mandatory clinical details policy for all microbiology samples. The only exceptions are those “difficult to obtain” samples taken from sterile site areas. For everything else, if there are no clinical details supporting the testing, then no testing is performed by the laboratory.

Now when I sign out a list of microbiology results I have clinical details on each and every request form. This is wonderful! In a good percentage of cases it changes both the testing and reporting of results. In other words the quality of results being produced has improved. And no longer will I get staff complaining to me that there are no clinical details on forms!

This has not been an easy policy to implement. Even after several months of preparation, there have been a few (almost inevitable) teethingĀ  problems which have had to be worked through. One key area is ensuring that all the staff members assess the clinical details provided in a consistent and standardised fashion. This has involved a lot of protocol development and these protocols are still in a process of evolution. For example “Erythema and increased pain leg ulcer” are acceptable details whilst “chronic leg wound” is not, and then there is the myriad of word variations in between. It is not straightforward!

Although most of the clinicians have been supportive of such a policy and indeed have embraced it by including excellent clinical details, there remains a small cohort who refuse to believe that the inclusion of clinical details on microbiology request forms is important. There are a few others that believe in the policy in principle but have concerns over the logistics.

The goal over the next year or so will be to continue to build a clinical details culture amongst clinicians so that clinical information on microbiology forms (and all laboratory request forms) is the expected norm. This represents a positive step for all the involved stakeholders; clinicians, laboratory staff and patients alike.

Along the same lines I hope that many other diagnostic microbiology laboratories both nationally and internationally adopt a similar stance. The presence of clinical details is a key element of effective diagnostic stewardship. Without them, you are already on a hiding to nothing…

Michael

 

“Taking the crap out of enteric microbiology”

Just because a stool sample turns up at your microbiology laboratory, it doesn’t mean you have to test it… This is old style microbiology reasoning, testing for everything in the hope that you will find something!

There are many different microbiology tests that one can do on a stool sample. Here is a sample list of what is offered at the lab I work at:

  • PCR for common bacterial pathogens, e.g. salmonella, campylobacter, shigella, VTEC, yersinia.
  • Culture for more opportunistic bacterial pathogens such as Aeromonas
  • EIA for cryptosporidium and giardia
  • GDH/PCR for C. difficile toxin
  • Faecal concentration and trichrome stain for ova, cysts and parasites
  • Immunochromatographic assay for rotavirus
  • Multiplex PCR for other enteric viruses (e.g. noro, astro, sapo)
  • Faecal antigen test for H. pylori.

With appropriate clinical details present, we can then choose objectively from the list above which tests are appropriate to perform for a specific sample.

However, without clinical details, it would be utterly unreasonable for the lab to do all of these tests, and without clinical details there is no way of deciding which tests we should be doing.

Yet so many microbiology labs still take this approach. Receive a stool sample and test it for something! This is blindfold microbiology.

Extending this philosophy further, clinical details of “diarrhoea” doesn’t really cut the mustard either. That is to some extent stating the obvious!

Fit healthy adults who present with a short history of diarrhoea in general do not require laboratory testing. Personally I get 2 or 3 episodes of loose stools every year. I am sure the rest of the world has a similar experience! I do not need laboratory testing. So clinical details simply of “diarrhoea” or “loose stools” is insufficient to justify testing. There needs to be more than that…

The lab I work at will only test stool samples if one of the following applies, even when clinical details of “diarrhoea” or something similar is on the form:

  • Something to indicate an illness on the more severe end of the spectrum, such as prolonged diarrhoea, bloody diarrhoea, hospitalised, systemic symptoms, etc.
  • Or something that suggests there might be a public health issue, e.g. food handler, group meal, overseas travel, farm worker, etc.

“Carte blanche” approaches to enteric microbiology are hideously costly, and also give rise to quality issues such as overdiagnosis and overtreatment.

If you test every stool sample you receive for putative pathogens such as Blastocystis hominis or Dientamoeba fragilis, you are going to end up overdiagnosing and overtreating a whole heap of people. Don’t go there!

By taking a considered and objective approach to microbiology testing of stool samples you can dramatically reduce the amount of testing that you perform, and increase the quality of results at the same time.

Michael

 

“The Sputum Factory”

It is the peak of the (Southern Hemisphere) influenza season here in New Zealand. Influenza has come early this year, and the season has been relatively busy to date, with a fairly even mix of Influenza A&B.

And it is not just influenza, there is plenty of circulating RSV, rhinoviruses and all those other less well known respiratory viruses that we know best by their appearance on extended respiratory viral panel menus.

However it is not just GPs and Emergency departments that feel the effects of the wave of respiratory viruses during the winter season. Microbiology departments get a surge in sputum samples arriving at the laboratory. Recently it has felt like my laboratory is simply a sputum processing factory!

And this is because any microorganism which infects the respiratory epithelial cells (bacteria or viruses) will inflame the respiratory epithelial cells and increase the production of “purulent” sputum. It doesn’t matter whether it is a bacterium or virus. Can the sputum colour discriminate between the two?? Only in the textbooks…

Sputum for bacterial culture is one of my least favourite microbiology samples! This is not just because of its appearance, but more because it suffers from appalling sensitivity and specificity when diagnosing bacterial pathogens, even when a pre-screening Gram stain is performed, as many labs do nowadays.

If sputum culture was subject to to FDA approval as a “diagnostic assay”, it wouldn’t have a prayer…

During the winter season when respiratory viruses abound, the prevalence of bacterial infection in the tested population will be relatively lower, with a consequent further deterioration in positive predictive value.

There are many guidelines that show the extremely limited value of sputum culture, particularly from the community setting, for the management of non-specific cough symptoms, acute bronchitis, and COPD. The most common clinical details we receive on sputum samples are things like “Cough”, “cough with purulent sputum”, “COPD”, or simply nothing at all. Yet we still accept these samples without question.

As a profession, sometimes I think we are too soft…

My lab is planning to introduce restrictions on what sputum samples are acceptable from the community setting, according to the published guidelines, so hopefully by next winter, we will be a haven of tranquility as opposed to a sputum processing factory.

Michael

Apologies for the picture, but it had to be done!