Monthly Archives: August 2013

Data Interpretation: Case Number 4


A mother tests HBsAg +ve on antenatal screening.


1) What other blood tests are indicated here in light of this reult?

2) What should all neonates born to HBsAg +ve mothers receive?

3) What laboratory tests should be performed on the baby?


Click here for answers with brief explanations.

“Conference stereotypes”

A lighthearted post for the weekend… which may or may not be applied to microbiology conferences. 

Conference Crawler: Every institution has one, possibly even every microbiology lab. Always on conference leave, floating from one conference to another, leaving little time in between for work. Abstract view of reality, good theoretical knowledge, but difficulty in dealing with practical “real life” problems. Lots of mini-shampoo bottles in soap bag.

Conference Businessman: Often found wandering the conference venue dressed in a suit (it’s not a wedding, nor a funeral…), and carrying a briefcase/shoulder bag. Looks more important than job suggests. Aloof, often mistaken for industry rep.

Conference Critic: Insists on standing up at the end of every talk to deliver a comment or a question, usually questioning the speakers findings. Inflated sense of self importance, likes sound of own voice.

Conference Networker: Knows everyone at conference, difficult to speak to for more than two minutes before he/she wanders off. Always has glass or coffee cup in hand. Inevitably arrives late for presentations.

Conference Plenary Speaker: Often elderly and may be difficult of hearing. Capable of delivering talk in his/her sleep and often does. Often delivers highly evidence based, but also highly tedious talks. Usually disappears into thin air immediately afterwards.

Conference Photographer: Attends every talk armed with an I-Pad or I-Phone. (No other apparatus will do). Insists on photographing every powerpoint slide with aforementioned apparatus. Often deficient in listening skills.

Conference Shopper: Rarely found at conference venue, well dressed, not always female.


p.s. Looking forward to going to the ECCMID conference next year in Barcelona (chosen primarily on venue). Hopefully I will not fulfil too many of these stereotypes!

“The exception and the majority”

When to only test for the majority and when to look for the exception dictates so much of our testing in microbiology.

For example:

  • Is it reasonable to put up plates to specifically look for Neisseria gonorrhoeae in every conjunctival swab?
  • Is it reasonable to give prolonged incubations to all sputa from immunocompromised patients in the hope of finding Nocardia?
  • Is it reasonable to exclude a Vancomycin Resistant Enterococcus in every urinary enterococcal isolate?
  • Is it reasonable to look for Arcanobacterium haemolyticum in all throat swabs?
  • Is it reasonable to look for Giardia lamblia in all stool samples?


You will all have your own opinions on these questions and there are no right or wrong answers.

What influences whether we only test for the majority, or look also for the exception depends on many factors, the cost of the testing, the severity of the disease, the local epidemiology, the trust that the users have in the laboratory, and many more… 

We cannot test for everything in the laboratory, we cannot cover for every exception. A lot of our testing policy is dictated by whether we let the exception rule the majority, or whether we test only for the majority at the expense of the exception.

As I have said, there is no right or wrong answer, but we must always be able to provide a rationale for what we do and don’t test for based on the factors above.


p.s. I have added a quick tutorial on Metronidazole to the website. Click here for tutorials.