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Emergence of antibiotic resistance
in a real life setting
Duncan Saunders1, Geoff Saunders2
1. University of Glasgow, 2. The Christie NHS Foundation Trust
Introduction
Results and discussion
There are few public health issues of greater importance than
antimicrobial resistance in terms of impact on society. This
problem is not restricted to the UK. It concerns the entire world
and requires action at local, national and global level1. This
poster discusses the link between the time taken to develop
antibiotic resistance in relation to antibiotic usage in an oncology
setting.
Over the two years antibiotic use was broadly the same with
peaks in August, October, February and March in 2011/2012
and September, December, January and March in 2012/2013. In
both years the most used antibiotic was meropenem, and the
least used linezolid.
During 2012/13 peak numbers of GRE cases were seen in April,
July, December and March. There was a strong correlation (0.65
-0.62) between monthly issues of antibiotics (February-January)
and GRE cases (April-March). This suggests the increase of
GREs is related to the use of antibiotics 2-3 months before.
Background
The emergence of strains of glycopeptide resistant enterococci
(GRE) are problematic since they pose challenges for treatment;
and in immunocompromised patients, may lead to greater
morbidity and mortality. Exposure to a number of different
antibiotics can promote the development of resistance2.
Following an observed increase in the isolation of GRE over a
period of time at the Christie Hospital the use of a range of
antibiotics was examined.
Methods
Pharmacy records of issues of five antibiotics (linezolid,
vancomycin, teicoplanin, meropenem and
piperacillin/tazobactam) were examined for the two year period
April 2011 to March 2013. The raw data was recalculated using
WHO defined daily doses (DDD) to allow comparison of different
dosage forms3.
Comparing use individually against the number of observed
GREs, Teicoplanin shows a strong correlation (0.68) for the
period of March 2012 to February 2013. Meropenem and
Piperacillin/Tazobactam both show a strong correlation 2-3
months
before,
Meropenem
0.64
at
3
months,
Piperacillin/Tazobactam 0.72 at 2 months and 0.58 at 3 months.
This difference in the timing of the associated GREs suggests a
difference in the formation of the resistant colonies. The
Glycopeptide, teicoplanin, has the shortest time line, it being
correlated to GRE infection one month after the use of the drug.
The
broad
spectrum
antibiotics,
Meropenem
and
Piperacillin/Tazobactam, have a longer period of time between
the administration of the drug and the correlated GRE infection,
3 months and 2 months respectively. This suggests a difference
in the way that the GRE colonies form following the use of these
antibiotics. Understandably the GRE infection following
treatment with a glycopeptide comes much quicker, suggesting
that the GRE colonies that survive are selectively resistant to the
antibiotic and are able to colonise and regrow unopposed. In the
use of broad spectrum antibiotics the mechanism in play seems
to take a longer period of time. This may be due to a number of
factors, yet to be determined.
Whilst the clinical significance of these findings on the treatment
of individual patients is as yet unknown, this audit reinforces the
need for good prescribing practice, ensuring prudent use of
antibiotics to keep development of resistant clones to a
minimum. Although the use of broad spectrum and glycopeptide
antibiotics cannot be avoided in the management of this group of
patients; oncology pharmacists should be aware of the timeline
between increased use of these agents and the emergence of
resistant strains. Patient care is improved through heightened
awareness of increased prevalence of GRE. Future work could
compare antibiotic usage and resistance patterns with other
similar trusts.
References
UK Five Year Antimicrobial Resistance Strategy 2013 to 2018.
Department of Health. London 2013
1.HPA – Antibiotic resistance.
http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/A
ntibioticAwareness/ Accessed on 10/07/2013 Last Updated
13/02/2013
2.WHOCC – Definition and general considerations.
http://www.whocc.no/ddd/definition_and_general_considera/
Accessed on 10/07/13 Last Updated 17/12/2009