Anti-microbial Stewardship in the Hospital Setting: “The Vicious Circles of Resistance”

Here are a few vicious circles that make the job of anti-microbial stewardship even more difficult than it already is:

1) Increasing rates of Multi-Drug Resistant Organisms (MDROs) increases the use of broad spectrum anti-microbials, which in turn increases further the MDRO rate. This is probably the main vicious circle at play. To break it requires a lot of work put into predicting which patient cohorts absoulutely need broad spectrum antimicrobials, and which cohort can “get away with” a narrower spectrum anti-microbial in the first instance.

2) Increasing availability of broad spectrum anti-microbials on the hospital formulary increases use of broad spectrum antimicrobials, which increases the resistance rates, which in turn encourages more broad spectrum antimicrobials being placed on the formulary. The premise behind this vicious circle is that if something is available, it is used. Institutions need to think very carefully what broad spectrum anti-microbials it has on their formulary. “just in case” or “personal preference” for me are poor arguments in the bigger scheme of things.

3) Increasing numbers of patients with MDROs on a ward increases chances of patients on the ward without MDROs being colonised with an MDRO, thus increasing tranmission risk further. The cascade effect. If I was lying in ICU with 7 other patients, and 5 of them have MDRO colonisation, then regardless of how good Infection Control is, I don’t fancy my chances of staying MDRO free.

4) Increasing MDRO rates leads to less chance of properly isolating patients, thus increases chances of MDRO transmission, which increases the MDRO rate. Not dissimilar to 3). We know some institutions have “run out” of isolation facilities, and thus have to prioritise Isolation Facilities to the highly Multi Resistant Drug Organisms (hMDROs)

 5) Higher MDRO rates, leads to antibiotic policies which include more broad spectrum antimicrobials which in turn further increases MDRO rates. If you have a hospital with very low MDRO rates, then it is much easier to omit antimicrobials like tigecycline, meropenem, daptomycin, linezolid etc etc, from your “admission antimicrobial policies”.

(If I was an artist I would illustrate these vicious circles as circles. Alas it was not to be..!)

There are almost certainly more vicious circles at play but I think these are the main ones.

I think these vicious circles go some way to explaining the vast differences in MDRO rates that we see between different institutions.

And the solution? I don’t think there is any miracle solution here. I certainly do not like defeatist attitudes as I have encountered in some hospitals with high MDRO rates. I.e. “No point in shutting the stable door after the horse has bolted.” I think the UK’s recent impact on MRSA rates shows that these vicious circles can be broken. However it requires a combination of strong leadership, co-operation between different stakeholders, and political will.

Food for thought…..


See also “Anti-microbial stewardship in the Hospital Setting: The dilemma.”


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