Tag Archives: antimicrobial stewardship

“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…


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. 🙂

“Too much knowledge…”


A little bit of knowledge can be a bad thing. So can too much…

The acronym  ESCHAPPM ( or something similar) will be familiar to most microbiologists. (a similar acronym SPICE, is sometimes used instead)

  • Enterobacter spp.
  • Serratia spp.
  • Citrobacter freundii
  • Hafnia spp.
  • Aeromonas spp.
  • Proteus spp.
  • Providencia spp.
  • Morganella morganii

Because we are clever microbiologists, we know this group of organisms may have inducible beta-lactamase activity, and we advise the clinicians of this, often provoking a reflex switch in anti-microbial therapy to carbapenems. Not only clinicians, but there are plenty of ID physicians who make this automatic transfer to carbapenems the moment the word ESCHAPPM is mentioned, my hospital included.

The thing is however, do all patients with infections by an ESCHAPPM organism require a carbapenem?

Almost certainly not…

If we use a carbapenem for every infection due to one of these organisms, then this amounts to a significant amount of carbapenems. This is therefore an important an important antimicrobial stewardship issue. We are supposed to be trying to decrease the use of broad spectrum antibiotics, not increase them.

But we have read the textbooks, and we are clever…

And yet, if we look at the literature, there is very little evidence to support the theoretical dangers of using a beta-lactam in such patients. In fact, there are several small studies out there that support the non-inferiority of beta-lactams in such patients, particularly in non-life threatening illnesses.

Not to mention there are other options out there, fluoroquinolones, sulphonamides, etc.

We are simply scared.

Here is what I generally do (rightly or wrongly):

  • In a patient with bacteraemia due to an ESCHAPPM organism, as long as they are clinically improving I am happy to continue therapy based on the phenotypic susceptibility results.
  • In patients with UTIs due to ESCHAPPM organisms, even if in hospital, I feel no need  whatsoever to move to carbapenems.
  • I reserve carbapenem use in “ESCHAPPM” patients to bacteraemic patients who are getting worse, and also for patients with chronic infections, e.g. prosthetic joint infection, on the rationale that the longer the treatment, the more chance you have of getting clinically relevant inducible beta-lactamase activity.

We need to take a more pragmatic approach to ESCHAPPM organisms and their treatment. We also need larger scale trials so we can be more confident in our decisions and adopt such approaches into guidelines.

and we need to be brave…


“How long is a piece of string?”


A question that often ‘scunners’ me is “What should the duration of the antibiotic course be for this patient?”

Let me get out my crystal ball…

It is a question I get at least once a day.

And my heart tends to sink a little on hearing it…

I have no problem (and quite enjoy) guiding the clinician to the right antibiotic, but I find this particular question on duration very hard to answer with any degree of personal conviction.

I usually give one of the ‘magical’ and hallowed numbers such as 3, 5, 7, 10 or (god forbid) 14,  usually along with a sizeable disclaimer saying that for the most part, antibiotic duration is very much an arbitrary and non-scientific decision.

Sure, for the more critical infections such as endocarditis, osteomyelitis and prosthetic joint infection there are guidelines on antibiotic duration which I try to adhere to, but even then there is not a lot of evidence to back these durations up, and such guidelines tend to compress all patients into the one category…

And for hospitalised patients with infections that don’t fall well into any particular guideline, my response is often along the lines of “Until they are better”, “As long as it takes” or even “How long is a piece of string?”

I suspect 95% of antibiotic courses are longer than they need to be, and this may well have undesirable effects, and not just on the patient themselves. I am a strong advocate of putting mandatory limits on the duration of antibiotic that can be prescribed in “one go” by the prescriber without clinical review. For me it is a key element of anti-microbial stewardship.


Check out this related article on antibiotic duration…