How many antibiotic susceptibilities do you release to the clinicians for any particular isolate?
At the extreme end of the scale, some microbiology laboratories think nothing of releasing 15-20 antibiotic susceptibilities for the one isolate. This sometimes happens in labs rich enough to have a Vitek or Phoenix where the system panels contain many different antibiotics, often customised for a particular institution.
However more is not always necessarily better…
The main reasons for not routinely releasing an antibiotic susceptibility on an isolate are as follows:
- Unnecessarily broad spectrum for the clinical indication.
- Low threshold to developing antibiotic resistance.
- Relatively poor efficacy compared to other antibiotics for the clinical indication.
- Logistically difficult to use.
The majority of mainstream diagnostic labs probably give a choice of 5-10 antibiotics per isolate. Even then that is still a lot of antibiotics for the clinicians to mull over. It also gives a lot of scope for non-standardised practice…
More laboratories, including my own, are looking more and more towards focused antibiotic reporting, in order to “guide” clinicians towards the optimal treatment regime.
For example we routinely release 2 antibiotics for a Staphylococcus aureus isolate from a general wound swab. (If MALDI-ToF succeeds in reliably differentiating between MSSA and MRSA, then one could potentially release flucloxacillin/cloxacillin alone, without doing formal susceptibility testing, and with a comment “Further susceptibilities available on request”)
We routinely release 4 antibiotics on urinary E.coli isolates. I am thinking of reducing this to 3.
For MSSA (Methicillin Susceptible Staphylococcus aureus) isolates from blood cultures and invasive sites we routinely release just the one antibiotic, flucloxacillin. The same principle applies with Streptococcus pneumoniae and penicillin from blood cultures. By doing this we make it crystal clear what the expected standard treatment is. Of course we have a few others ‘up our sleeve’ should they be required in the case of allergy, treatment failure etc.
And then of course it is always important to remember that we have the choice of releasing (or testing) zero antibiotics, where the clinical details are absent or they are not indicative of acute infection. We should probably use the zero option more, along with a comment saying “Antibiotic susceptibilities available on request”.
Occasionally we get calls from clinicians, a little bit upset or grumpy that we have not released more antibiotics. Being thick skinned, I don’t mind this at all. It gives me the opportunity to build relationships with the clinicians, and also to explain our thinking…
Michael