Fw: [asid-ozbug] pre-operative disinfectants

[Matthias.Maiwald@KKH.COM.SG Subject: Fw: [asid-ozbug] pre-operative disinfectants MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Message-ID:]

Dear Group,

Just cross-posting my comments from OzBug. (Sequence of comments from
bottom to top). This issue was also discussed in a similar way on AICA
List.

Best regards, Matthias.

—
Matthias Maiwald, MD, FRCPA, D(ABMM)
Consultant in Microbiology
Department of Pathology and Laboratory Medicine
KK Women’s and Children’s Hospital
100 Bukit Timah Road
Singapore 229899
Tel. +65 6394 1389
Fax +65 6394 1387

—– Forwarded by Matthias MAIWALD/LAB/KKH on 29/06/2010 08:28 AM —–

Matthias.Maiwald@
kkh.com.sg
Sent by: To
asid-ozbug-bounce “Ingram, Paul”
s@malbec.burnet.e
du.au cc
asid-ozbug@burnet.edu.au,
asid-ozbug-bounces@malbec.burnet.ed
17/06/2010 10:27 u.au
AM Subject
Re: [asid-ozbug] pre-operative
disinfectants

Dear Paul,

I have dealt with this question extensively during my time in Adelaide (at
Flinders) and subsequently. I have also made a submission to the NHMRC
guideline committee while the draft was out for public comment, and I have
given a number of talks to surgical and infection control audiences on the
issue of surgical (and general) skin antisepsis (‘skin prep’). I am happy
to send some of the overview materials that I have prepared, but it might
be better outside OzBug, because sending uninvited attachments to OzBug may
not be the best thing.

A few key issues:

The agents in question (alcohols, chlorhexidine, povidone-iodine) have been
studied extensively since the 1970s. It is clear that alcohols have
significantly greater antimicrobial activity against microorganisms on skin
than the other two agents when they are used in aqueous solution. The
difference is typically about 1 log (i.e. a tenfold difference) in favour
of the alcohols. Alcohols have the greatest immediate antimicrobial killing
effect, while they have no residual activity. The other two agents have
significantly inferior immediate effect, but they appear to have persistent
action (chlorhexidine does, the one of PVP-I is questionable). Because it
is an advantage to have persistent action on skin and under the surgical
drapes for the time of surgery, it is an advantage to use a mix of alcohols
plus one of the two other agents (e.g. 70% isopropanol plus 2%
chlorhexidine), in order to provide immediate kill plus persistence for the
time of the operation.

A table with a spectrum of activity and immediate vs. persistent activity
of skin antiseptics has been published in the CDC guideline on prevention
of surgical site infections (Mangram et al. 1999) as well as in the WHO
hand hygiene guideline (2009).

It is also clear that alcohols are only suitable for superficial skin and
unsuitable to be used on mucous membranes (e.g. oral, ENT, eye, vaginal
surgery), so that aqueous agents have to be used for mucous membranes.

Several countries in central Europe have been using alcohol-based surgical
skin antiseptics for decades, and because of the well-known significant
difference in antimicrobial kill (see above), ethics committees in those
settings in Europe would not have approved a study such as the NEJM one
(Darouiche et al. 2010).

In addition to the Darouiche 2010 NEJM study, there are several other
clinical studies (with SSI rates as outcome) that document quite clearly
that either alcohol-based preps or intensified skin prep regimens (vs. less
intensive ones) make a clear positive impact on SSI rates, thus confirming
the validity of the microbiological studies.

It is clear from a synopsis of the literature that skin is the most
significant causative source of SSIs in clean surgery (this includes
orthopaedic surgery), whereas in contaminated surgery, the causation shifts
and other sources assume (in relative terms) a greater role.

We have also assessed the issue of fire risk from flammable skin preps
(Maiwald M et al. Letter to the Editor. ANZ J Surg 76: 422-3; 2006), with
the following conclusions: (1) fires from flammable skin preps are
extremely rare, (2) all cases for which there is background information
available have been caused by inadvertent misuse, e.g. pouring the
antiseptic over the patient, not waiting for the skin to dry, causing
pooling or wetting of drapes, using diathermy on alcohol-wet patients,
etc.), and (3) weighing the risk of surgical fires against the risk of
surgical site infections (SSIs), it becomes clear that even a minimal
reduction in SSI rates outweighs the (well preventable) risk of surgical
fires by several orders of magnitude.

There are two other things that appear to be important on microbiological
grounds and based on anecdotal and empirical findings. These are: (1) that
repeated application of the skin antiseptic with some mild friction and (2)
a sufficient contact time of the antiseptic on skin appear to be important.
Concerning (1), there are no published guidelines, but most experts in skin
antisepsis that I have talked to recommend 3 repeated applications, and
concerning (2), the Royal College of Surgeons of Australasia in their
infection control guideline recommends “at least 2 but preferably 5
minutes” of contact time before commencing surgery. (I am not sure how many
Australian surgeons are aware of their own College’s contact time
recommendation).

In Adelaide, several surgical units have successfully implemented the
change from aqueous to alcoholic skin preps (for superficial skin) without
any problems, but since I have moved away from Adelaide, I have not been
able to follow up on further details.

Since there are some issues to be aware of (see above), it appears that
education and information of surgeons is important. While in Adelaide, I
have given a number of talks to surgical units (e.g. proper usage,
avoidance of fire risk, etc.).

Best regards, Matthias.

—
Matthias Maiwald, MD, FRCPA, D(ABMM)
Consultant in Microbiology
Department of Pathology and Laboratory Medicine
KK Women’s and Children’s Hospital
100 Bukit Timah Road
Singapore 229899
Tel. +65 6394 1389
Fax +65 6394 1387

“Ingram, Paul”
To
Sent by:
asid-ozbug-bounce cc
s@malbec.burnet.e
du.au Subject
[asid-ozbug] pre-operative
disinfectants
17/06/2010 09:09
AM

Dear Ozbuggers,

Earlier this year NEJM published an RCT comparing 2% chlorhexidine-alcohol
vs povidine-idoine for prevention of surgical site infection demonstrating
superiority of chlorhex-alchohol, as evident by a 41% reduction in the ITT
analysis (N Engl J Med 2010;362:18-26).

Currently both the Australian Guidelines For The Prevention and Control of
Infection in Healthcare Consultation 2010 draft and the 2008 SHEA-IDSA
guidelines on prevention of SSI suggest either chlorhex or iodine based
pre-op disinfectants. Whether this should still be the case is presumably
now in doubt.
We are considering changing our hospital policy in keeping with the study
findings. The cost of 100mL of 2% chlorhex-alcohol and povidine-iodine from
our local supplier is almost equivalent ($3-4/100mL).
Are others considering changing their local pre-operative disinfectant
practices/policy? If so, what have their experiences been? Perceived
barriers would be the inherent inertia within surgeon practices, concerns
about the ability to extrapolate beyond the study population
(clean-contaminated surgery- ie elective entry into respiratory, biliary,
gastrointestinal, urinary tracts and with minimal spillage. This does not
include elective orthopedic surgery, nor contaminated emergency surgery),
worries about toxicity (eg keratitis with chlorhex) and flammability of
alcohol. The performance of alcohol (vs aqueous) based iodine solutions is
also not clear, as this was not included in the RCT.
Paul Ingram
Microbiology/Infectious Diseases Registrar,
Sir Charles Gairdner Hospital, Perth.

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