Decontamination of the Digestive Tract (SDD)
patients at high risk of acquiring nosocomial infections causing increased
mortality, morbidity, length of stay and costs
survey 45% of patients infected of which 21% acquired in ICU
common are pneumonias, other lower respiratory tract infections, urinary
tract infections and blood-stream infections
mortality for VAP: 24-30%
mortality for blood-stream infections 28-35%
risk is the result of multiple factors
of underlying disease
and prolonged use of invasive devices
exposure to potentially pathogenic organisms
healthy patients indigenous gut and oropharyngeal flora remain very static
over time. Overgrowth of potentially pathogenic organisms is prevented by
critically ill patients these mechanisms are compromised by the underlying
disease process, instrumentation and drugs resulting in
spectrum bacteria eradicates indigenous flora and loss of colonization
a few days of ICU admission normal flora replaced by potentially pathogenic
organisms (in >2/3 of patients) in oropharynx then stomach and gut.
Micro-aspiration of contaminated upper GI tract fluid most plausible and
demonstrable cause of infection. Translocation through the gut wall is a
theoretical possibility which has been demonstrated in animal studies but not
convincingly in humans.
of potentially pathogenic organisms from the mouth and GIT by local
administration of non-absorbable antibiotics
± short course of systemic
antibiotics for early / incubating respiratory infections
until surveillance cultures show GIT decontamination (usually 4 days)
early established infection by community acquired pathogens (e.g.
Streptococcus pneumoniae, haemophilus influenzae) which may be aspirated
until enteral drugs have decontaminated the GIT
ASAP on admission, continue enteral drugs until extubated or leave ICU
cultures to monitor effectiveness of SSD
hygiene to prevent cross-infection
is also used for the prevention of gut-derived infections in acute
necrotizing pancreatitis and liver transplantation.
SDD – for and against
studies with conflicting results.
appears to reduce infection rates, especially in critically ill surgical
patients (who have a higher rate of nosocomial pneumonia and a higher
attributable mortality compared to medical patients)
SDD is well accepted in Europe but uptake of the technique
has been slow in other countries especially USA despite evidence
of improved infection rates and possible improved mortality rates with
absence of harm and little increased cost from trials with good design.
on mortality is less clear – most studies are underpowered and cannot
exclude a treatment benefit
group of patients likely to benefit from SDD not well defined
nature of best SDD not well defined: topical alone versus topical plus
Concerns about resistance: although good studies have showed
little change in resistance patterns, increased colonization (but not
infection) with Gram-positive organisms is noted. In some of these
studies the incidence of MRSA, and resistant entercocci is very low, and
the safety of SDD is questionable in centres where incidence of these
potentially more pathogenic organisms is high. Nasal mupirocin may be
helpful. Some argue that SDD will add to add to resistance problems,
others that it will reduce then by preventing infection and subsequent
use of antibiotic.
If effect is more marked with systemic antibiotics than
topical alone is this simply akin to the peri-operative antibiotics that
most surgical patients already receive?
Inconvenience of additional drugs and surveillance culturing
Possible increased drug costs
R et al
patients from 33 trials
of systemic and topical Rx reduced respiratory infection rates and overall
odds ratio 0.35 (0.29-0.41)
odds ratio 0.8 (0.69-0.93)
in mortality = 6% (30 to 24%)
AB and Marshall JC
predominantly surgical or medical patients separately
was reduced for surgical patients (odds ratio 0.7 [0.52-0.93]) while no such
affect was demonstrated for medical patients (odds ratio 0.91 [0.71-1.18])
effect was seen in topical and systemic therapy combined.
was reduced in both subsets, although bacteraemia was only reduced in
Nieuwenhoven CA et al
the methodological quality of SDD trials and found an inverse relationship
between trial quality and benefit of SDD on incidence of pneumonia, and no
relationship between trial quality and mortality rates. May have resulted in
over optimistic estimates of the effect of SDD in meta-analyses.
WA et al 2002
trial showed in 527 mainly surgical and trauma patients showing reduced
infection rates and reduced organ failures but not ICU mortality in patients
given combined topical and systemic SDD. In a predefined subgroup of patients
with mid-range APACHE scores (20-29) ICU, hospital and one year mortality was
significantly reduced. Surveillance cultures showed no change in resistance
patterns although there was increased colonization (but not infection) by
Sánchez García M et al 1998
mainly medical patients reduced pneumonia rates but not ICU mortality in
patients given combined topical and systemic SDD.
DCJJ et al 2001
decontamination without GIT decontamination or systemic therapy reduced rates of
VAP in 227 critically ill patients, underpowered to show a survival benefit.
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© Sarah Ramsay February 2003