Tag Archives: textbooks

Sterile Pyuria: Horses for Courses

Open most microbiology textbooks (particularly the older ones) and you will find tuberculosis high on the differential diagnosis of sterile pyuria.

This might be true in some parts of the world, but I suspect in a lot of places, and certainly where I work in New Zealand, renal tuberculosis is an extremely rare cause of sterile pyuria.


I would estimate about 1 in 1000 cases of sterile pyuria are due to TB here in NZ. There are much more common causes such as recently treated UTI, contamination with vaginal leucocytes secondary to chlamydia, candida infection, infection due to fastidious organisms etc etc.

GPs often reflexively order 3 Early Morning Urines for mycobacterial culture when they see a report suggesting sterile pyuria (because of those textbooks). In some areas of the world this might be appropriate, but in our lab in New Zealand, we like to see either repeated sterile pyuria results on the same patient or strong supporting clinical information before even accepting urines for TB culture.

Along the same lines if you have a young sexually active adult with sterile pyuria with no obvious cause, then excluding chlamydia should be at the forefront of your mind, and an appropriate comment to suggest this should always be added to such reports.

Horses for Courses….


I am away at a virus conference for the next few days…..

“The Smiling Executioner”

I have done many exams in the past, several of them microbiological. They have been consistent both in their lack of originality and also their focus on knowledge base, often requiring regurgitation of factual knowledge learnt from textbooks.


The primary focus of any professional exam should first and foremost be to ensure that the candidate has a good understanding of the subject, is safe, trustworthy, and knows when to ask for help. These are difficult enough attributes to assess.

However in addition, I think exams should also at least attempt to assess candidates on their ability to think on their feet, to innovate, to adapt and to lead. These are attributes I would certainly also be looking for in a prospective employee.

Here are a few examples of exam questions I have thought of that at least try to assess these additional attributes:

  • Summarise your prototype design for a “perfect” incubator?
  • You have been asked to put together a multiplex PCR for enteric bacteria. What micro-organisms would you include and why?
  • You have been asked to restrict to eight the number of different types of agar plates that the laboratory orders in. Which agar plates would you choose in this sub-set of eight and why?
  • You happen to notice that very few agar plates are growing Staphylococcus aureus in the morning plate read. Give reasons for this and what further investigations are required?
  • The Laboratory Biohazard cabinet will be out of action for two days. How will this affect your laboratory service and how will you cope?
  • A sales rep meets with you, presenting a new Enyme Immuno Assay which he/she proclaims to have 100% sensitivity, 100% specificity and 100% positive predictive value. What questions would you want to ask him/her in order to get the real story?

Most importantly, these are the sort of questions that cannot be answered straight from a textbook, although obviously a good deal of knowledge and understanding is required for all the issues involved.

I suspect not all microbiology students would like these types of questions. Maybe it is just as well I am not an examiner. Otherwise I would probably be known as the “Smiling Executioner”!


“Textbooks: A Laboratory Hazard?”

Every laboratory I have been to has at least one or two shelves of textbooks. I am talking here about the traditional paper textbook.120px-Paperback_book_black_gal_svg

On looking more closely at the textbook collection of each laboratory, there might be a couple that are up to date, then the rest will undoubtedly be of varying ages with a few of antique value.

So how old does a textbook have to be before it loses it’s usefulness? Well, like people they all age at different rates. It depends to some extent on what has changed with regards to the topic matter. You might find a book on syphilis is still useful 10-15 years after publication, whereas a book on Hepatitis C treatment would be almost useless only 5 years from the date of issue due to the rapid changes in this area..

In general most of us still like paper textbooks because it is what we were brought up with. It is how we learnt. However I am concerned that by referring to out of date textbooks in the laboratory, we are not doing ourselves or the patients any favours.

I still have a few paper textbooks on my shelves (It makes vistors believe I am a microbiologist!). However I try and force myself not to use them as they are all years out of date.

I would encourage laboratories to move towards online texts (even then it is still important to check the publication date) and to clear those shelves, maybe apart from the antique textbooks which can be put behind lock and key for the safety of both the book and the user…