Tag Archives: esbl

“The Blind Microbiologist”

blindI have authorised a little flurry of urine cultures recently with ESBL producing organisms. A good proportion of these had no clinical details, and a significant proportion were from Rest Home residents.

It is the lack of clinical information which frustrates me the most..

These urine samples could have been taken for any one of the following reasons:

  • a)  The nurse at the Rest Home had decided to routinely dipstick the urine of all the residents.
  • b)  The urine was taken and sent to the lab because there was a “whiff” of urine from the patient.
  • c)  The patient is known to be MDRO colonised, so another urine was taken to ‘check’ if it is still there.
  • d)  The patient gets a 6 monthly urine sample sent to the lab because they are known to have a history of recurrent UTIs.
  • e)  The patient is new to the practice or Rest Home so an initial screening urine was taken off.
  • f)  The patient had symptoms or signs suggestive of an acute urine infection.

It is dangerous to assume that the majority of urines arriving at your lab (without clinical details) are specifically for reason F.

My bet is that this is not the case…

When we release antibiotic susceptibilities from the laboratory on a urine culture, we are essentially giving the green light for antibiotic use. An ‘endorsement’ of sorts, a licence to treat, regardless of the clinical indication. In essence we are reporting susceptibilities “blind”…

However reason F is the only reason listed above where I would actually want to routinely release susceptibilities. It could easily be argued that for the laboratory to release susceptibilities on an MDRO without there being any clinical details, simply represents poor antibiotic stewardship.

My laboratory has recently made the provision of clinical details mandatory for Infectious serology tests. If no clinical details, then the serum is simply stored until they are provided. Uptake by clinicians has been very good, and there have been virtually no complaints. What is there to complain about? The quality gains that we have made from this have been very significant.

I am now wondering whether a similar model should be applied to urine samples. Obviously specimen integrity (and ease of recollection) should be taken into account, but there are a couple of possible models as follows:

  • No clinical details, urine stored for maximum 24 hrs until provided. Otherwise recollect.
  • No clinical details, urine processed, but susceptibilities only released on provision of clinical details.

As microbiologists, I don’t think we should be scared of having these kinds of conversations. In fact, I believe we owe it to our patients…


p.s. Book sales going well, approximately 50 copies ordered so far. They are being posted within 24 hours of receipt of order but obviously will take a few days to arrive depending on location. Let me know if any problems in the ordering process. Thanks.

Antimicrobial Resistance in New Zealand

These are approximate antimicrobial resistance rates in NZ currently:

9% of all Staph aureus isolates are resistant to methicillin (MRSA).

1% of all E.coli isolates are Extended Spectrum Beta Lactamase producers (ESBLs).

10% of all Klebsiella pneumoniae isolates are ESBLs.

<1% of all enterococci are vancomycin resistant (VRE).

There are just a handful of metallobetalactamases, mostly in people who have travelled abroad.


By international standards I think these are very low rates. How do they compare with the country you live in?

It would be nice to think that this was due to the great antimicrobial stewardship, fantastic infection control and well regulated antimicrobial licensing that we have in NZ! Off course these all play a part, but in actual fact the more likely reasons are due to NZ’s geographical isolation and sparse population, which are inherent advantages.

Let’s hope that the rates stay this low…