Tag Archives: antimicrobial stewardship

“A paradigm shift…”

At the moment most antibiotics are initiated without waiting for the microbiological result, if they are thought to be clinically necessary.

Quite right too.

This is so called “empirical therapy”.

There is a good reason for this. Traditionally, microbiology tests have neither been good enough nor fast enough to make the antibiotic prescription dependent on the result.

Take for example the patient who sees his GP with a productive cough and fevers. The GP is not going to say to the patient “Let’s just wait a few days until we get the sputum culture result back. By the way there is a good chance it will be negative even if you do happen to have a pneumonia. And on the flipside, if it does grow something it might just represent the bacteria in your throat.”

No chance…, the GP will simply prescribe an antibiotic based on the most likely pathogens, and also the local antibiotic susceptibility patterns.

Along the same lines, the GP is not going to say to the patient a couple of days later. “Your sputum sample has come back negative, so let’s stop your antibiotic.” Sputum cultures are nowhere near sensitive enough to allow this approach.

On the very odd occasion, the treatment will actually change as a consequence of the microbiology result, if there happens to be an unusual or resistant organism.

And sputa are only one sample type. Ear swabs, peri-anal swabs, & ulcer swabs probably have even less impact on patient management…

In fact for the vast majority of  samples (probably > 95%) that get processed by the microbiology laboratory, the impact on patient management is rather small indeed.

However change is coming on to the horizon. The newer microbiological tests, and in particular the polymerase chain reaction (PCR) assays, are both fast enough and sensitive enough to start genuinely impacting on patient management right at the time of prescribing.

Take the following potential examples:

  • Macrolide antibiotics could be witheld in a patient with suspected whooping cough until the Bordetella pertussis PCR is back.
  • Patients with urethral discharge and suspected gonorrhoea would only be treated if the Neisseria gonorrhoeae PCR result comes back positive.
  • Patients with meningo-encephalitis could have acyclovir to cover HSV, dependent on the CSF viral panel result.
  • Legionella cover in a patient with moderate to severe community acquired pneumonia could be dependent on the result of the Legionella PCR in a sputum sample.

These are all tests which, if performed quickly enough, can significantly reduce the amount of antibiotics given to the tested cohort, so they all have potential to play a big part in any antimicrobial stewardship program.

So we need to get such assays into our microbiology laboratories, whatever it takes.

Microbiology matters, but we need to ensure that we utilise new tests and technology to make it matter even more…

Michael

 

“To err is human”

Those that know me, will be aware that I am a passionate believer in having clinical rationale and clinical context as pre-requisite for all microbiology samples that are processed by the laboratory.

Exactly the same principles should apply for antibiotic prescriptions…

There are various reasons why a clinician might prescribe an antibiotic:

  • Fear: That if an antibiotic is not prescribed, then any suspected infection might increase in severity or even be potentially life threatening.
  • Pressure: Pressure to prescribe an antibiotic from the patient or their relatives.
  • Action: To be seen to be doing something positive for the patient.
  • Justification: That prescribing an antibiotic justifies the cost or time of the consultation.
  • Loyalty: If an antibiotic is not prescribed then the patient may go elsewhere to get what they want.
  • Bacterial infection: That there is a genuine suspicion of a bacterial infection where the evidence shows that antibiotics are indicated in that particular clinical scenario.

It would be foolish to think that the real prescribing reason is always the last one on this list.

Humans are subject to all sorts of internal biases, and external pressures. We are in essence, fundamentally flawed. It is therefore wrong to expect us to always prescribe antibiotics for the right reasons as opposed to the “not so right” ones.

In other words we need tight controls on our decision making behaviours.

At the moment a clinician can write a prescription for most antibiotics without including any indication as to why the antibiotic was prescribed.

This needs to change.

It is my belief that all antibiotic prescriptions should have the clinical indication for prescribing included on the prescription form as a pre-requisite for dispensing, in both community and hospital settings.

Otherwise the pharmacist is essentially dispensing blindly.

Once such a system is in place, then specific criteria can start to be applied for certain infections in order for an antibiotic prescription to be valid/approved.

Then we can start getting some real controls in place for the purposes of antibiotic stewardship.

The days of clinicians being able to request laboratory tests and prescribe antibiotics without providing a clinical rationale are numbered.

I hope…

Michael

“The Antibiotic Free Period”

The patients who get the most courses of antibiotics are as expected, the ones who get the most infections, and these infections are often recurrent at the one site. A few examples are the elderly person who gets recurrent urinary tract infections, the toddler who gets recurrent otitis media, or the patient with chronic obstructive pulmonary disease (COPD), who gets recurrent bouts of bronchitis.

The antibiotic selection pressure on such patients is often intense, and one can often see by observing their microbiology results over time, that the infecting organisms become increasingly resistant, until multi-drug resistant organisms (MDROs) appear, and the clinician is forced to resort to less routine and more exotic antibiotics to treat the infection.

Whilst some of these “infections” will absolutely require antibiotics, many don’t, and many more were probably not bacterial infections in the first place.

What these patients really need is “An Antibiotic Free Period” . A period where the playing field is level. When MDROs have to compete against their susceptible counterparts in the absence of selection pressure, the increased fitness of the susceptible bacteria will win in the end. (This may take a while, and varies from patient to patient, and from organism to organism, but it will happen eventually.)

MDROs really don’t like level playing fields, they much prefer the odds slanted in their favour…

How can the microbiology laboratory assist in creating antibiotic free periods for patients?

Well we can add a comment to the result, for example “Uncomplicated otitis media does not routinely require antibiotic therapy” or “The isolation of pseudomonas from a patient with COPD does not imply acute infection.”, etc., etc.

or we can simply withold susceptibilities. For example an E. coli in a urine from an elderly Rest Home patient could have a comment along the lines of: “No clinical details have been provided with this sample. Asymptomatic bacteruria occurs in a significant proportion of elderly patients. If this patient has urinary symptoms, and they are continuing, please contact the laboratory for antimicrobial susceptibilities.”

It is my experience that the presence of an MDRO on a microbiology result report causes a reflex reaction from the requestor and increases the chance that the patient will be treated with antibiotics.

However the exact opposite should really apply. The threshold for treating an infection caused by an MDRO, as opposed to a susceptible one, should go up, not down.

One of the roles of microbiology laboratories, and clinical microbiologists, should be to facilitate antibiotic free periods where the opportunity arises…

Michael

There were seven new subscribers last week during the “Purple Cow Giveaway”. Rather than draw 5 from 7, I will ensure all seven new subscribers get a copy of my book. 🙂