Transcript Document

Infection complications in surgery
Inflammation
Inflammation is the local physiological
response to tissue injury. It can be acute or
chronic.
Acute inflammation
This is the initial tissue reaction to a wide
range of agents. Accumulation of neutrophil
polymorphs in the extracellular space is
diagnostic. It lasts hours to days.
Causes
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Physical and chemical, e.g. mechanical
trauma, X-rays, acid, alkali.
Infection: bacteria, viruses, parasites, fungi,
or protozoa.
Ischaemia.
Hypersensitivity.
Macroscopic appearance
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Calor
Rubor
Tumor
Dolor
Functio laesa
(heat, redness, swelling, pain, and impaired
function).
Special macroscopic appearances
include:
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serous inflammation + abundant fluid rich
exudates, e.g. peritonitis;
catarrhal inflammation + mucus
hypersecretion, e.g. common cold;
haemorrhagic inflammation + vascular injury,
e.g. pancreatitis;
suppurative inflammation + pus produced to
form abscess or empyema
Special macroscopic appearances
include:
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fibrinous: exudates contain fibrin, which
forms coating, e.g. pericarditis;
membranous: coating of fibrin and epithelial
cells, e.g. laryngitis;
pseudomembranous: superficial mucosal
ulceration with slough, e.g.
pseudomembranous colitis secondary to
Clostridium difficile
necrotizing (gangrenous) inflammation +
tissue necrosis
Microscopic changes
Mediated by endogenous chemicals released
by cells (histamine, prostaglandins,
leukotrienes, serotonin, and lymphokines)
and plasma factors (complement, kinin,
coagulation, and fibrinolytic cascades).
Changes are as follows
Changes in vessel calibre and flow
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Immediate and transient smooth muscle
vasoconstriction.
Vasodilation (active hyperaemia) lasting
15min to hours.
Capillaries, then arterioles dilate to
increase blood flow.
Increased vascular permeability
and fluid exudate
•
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•
Capillary hydrostatic pressure is
increased.
Endothelial cells contract, creating
gaps.
Plasma proteins escape into
extracellular space.
Increase in colloid osmotic pressure
draws more fluid.
Formation of cellular exudates
–
–
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Accumulation of neutrophil polymorphs in
extracellular space.
Begins with margination of neutrophils (flow next
to vessel walls).
Neutrophils then adhere to vessel walls:
mechanism unknown.
Formation of cellular exudates
–
–
Migrate by amoeboid movement through gaps
between cells.
Neutrophil polymorphs phagocytose debris and
kill microbes intracellularly using oxygendependent (H2O2 and hydroxyl radicals) and independent (lysosymes) means.
Sequelae of acute inflammation
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Resolution. Restoration of tissue to normal.
Likely if minimal tissue damage, rapid
destruction of causal agent, rapid removal of
exudates by good vascular drainage, and
organ with restorative capacity, e.g. liver.
Suppuration: formation of pus.
Organization: replacement by granulation
tissue (see below).
Chronic inflammation.
Chronic inflammation
This is an inflammation where lymphocytes,
plasma cells, and macrophages
predominate.
Granulation tissue often accompanies it
Causes
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Resistance of infective agent to phagocytosis (TB,
viral infections).
Foreign body (endogenous, e.g. urate, or
exogenous, e.g. asbestos).
Autoimmune (e.g. contact hypersensitivity, RA,
organ-specific).
Primary granulomatous disease (e.g. Crohn's,
sarcoidosis).
Unknown aetiology (e.g. ulcerative colitis).
Macroscopic appearances
The commonest appearances are:
 chronic ulcer, e.g. peptic ulcer;
 chronic abscess cavity, e.g. empyema;
 thickening of wall of hollow viscus, e.g.
Chrohn's disease;
 granulomatous inflammation, e.g. TB;
 fibrosis, e.g. chronic cholecystitis.
Microscopic changes
Lymphocytes, plasma cells,
and macrophages
predominate; neutrophil
polymorphs are scarce;
eosinophil polymorphs are
present. Fluid exudate is not
prominent.
Granuloma
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This is different to granulation tissue
A granuloma is an aggregate of epithelioid
histiocytes.
Causes
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Specific infections: TB, fungi, parasites,
syphilis.
Foreign bodies:
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endogenous: necrotic bone or fat, keratin, urate;
exogenous: talc, silicone, asbestos, sutures.
Drugs: sulphonamides, allopurinol.
Unknown: Crohn's, sarcoidosis, Wegener's
granulomatosis.
Surgical Infections and Choice of
Antibiotics
During the second half of the 19th century
many operations were developed after
anesthesia was introduced by Morton in
1846, but advances were few for many
years because of the high rate of infection
and the high mortality that followed
infections.
Surgical Infections and Choice of
Antibiotics
By the beginning of the 20th century,
following the work of Ignaz Philipp
Semmelweis and later with the
introduction of antisepsis into the
practice of medicine by Joseph Lister,
reduced infection rates and mortality in
surgical patients were seen.
Surgical Infections and Choice of
Antibiotics
The work of Holmes, Pasteur, and Kocher
in infectious diseases, as well as the
operating room (OR) environment and
discipline established by Halsted,
continued to prove the aseptic and
antiseptic theory to be the first effective
measure for preventing infections in
surgical patients.
These initial principles helped change
surgical therapy from a dreaded event,
with infection and death commonplace, to
one that alleviates suffering and prolongs
life with predictable success when
carefully performed.
With the introduction of antibiotic therapy
in the middle of the 20th century, a new
adjunctive method to treat and prevent
surgical infections was discovered, and
hope for final elimination of infections
was fostered.
However, not only have postoperative
wound and hospital-acquired infections
continued, but widespread antibiotic
therapy has also often made prevention
and control of surgical infections more
difficult.
The present generation of surgeons has
seen increasing numbers of serious
infections related to a complex
combination of factors, including the
performance of more complicated and
longer operations, an increase in the
number of geriatric patients with
accompanying chronic or debilitating
diseases,
many new surgical procedures with
implants made of foreign materials, a
rapidly expanding number of organ
transplants requiring the use of
immunosuppressive agents, and
increased use of diagnostic and treatment
modalities that cause greater bacterial
exposure or suppression of normal host
resistance.
The modern surgeon cannot escape the
responsibility of dealing with infections
and, when dealing with them, of having
knowledge of the appropriate use of
aseptic and antiseptic technique, proper
use of prophylactic and therapeutic
antibiotics, and adequate monitoring and
support with novel surgical and
pharmacologic modalities, as well as
nonpharmacologic aids.
Basic understanding of how the body
defends itself against infection is
essential to the rational application of
surgical and other therapeutic principles
to the control of infection.
SURGICAL SITE INFECTIONS

Surgical site infections (SSIs) are
infections present in any location along
the surgical tract after a surgical
procedure. In 1992 the Surgical Wound
Infection Task Force published a new set
of definitions for wound infections that
included changing the term to SSI.
Unlike surgical wound infections, SSIs
involve postoperative infections occurring
at any level (incisional or deep) of a specific
procedure. SSIs are divided into incisional
superficial (skin, subcutaneous tissue),
incisional deep (fascial plane and muscles),
and organ/space related (anatomic location
of the procedure itself). Examples of
organ/space SSIs include intra-abdominal
abscesses, empyema, and mediastinitis
SSIs are the most common nosocomial
infection in our population and constitute
38% of all infections in surgical patients.
By definition, they can occur anytime
from 0 to 30 days after the operation or up
to 1 year after a procedure that has
involved the implantation of a foreign
material (mesh, vascular graft, prosthetic
joint, and so on).
Incisional infections are the most
common; they account for 60% to 80% of
all SSIs and have a better prognosis than
organ/space-related SSIs do, with the
latter accounting for 93% of SSI-related
mortalities.
The microbiology of SSI is related to the
bacterial flora present in the exposed
anatomic area after a particular procedure
and has been relatively fixed during the
past 30 years, as shown by the National
Nosocomial Infection Surveillance System
(NNIS) established by the Centers for
Disease Control and Prevention (CDC).
The CDC is in the process of revising and
renaming this program as the National
Healthcare Safety Network (NHSN). This
study has shown that Staphylococcus
aureus remains the most common
pathogen in SSIs, followed by coagulasenegative staphylococci, enterococci, and
Escherichia coli.
However, for clean-contaminated and
contaminated procedures, E. coli and
other Enterobacteriaceae are the most
common cause of SSI. In addition, some
emerging organisms have become more
common in recent years.
Vancomycin-resistant enterococci (VRE)
and gram-negative bacilli with unusual
patterns of resistance have been isolated
more frequently. Of particular interest is
the growing frequency of Candida species
as a cause of SSI and surgical infections
in general
Understanding the microbiology of SSIs
is important to guide initial empirical
therapy for infections in a specific patient,
as well as for identification of outbreaks
and selection of strategies for the
management of prophylactic antibiotics,
as discussed later in this chapter.
Causes and Risk Factors
Multiple risk factors for SSI have been
identified over time and can all be
compiled within one or more of the three
major determinants of SSI: bacterial
factors, local wound factors, and patient
factors
The interaction between these three is
what determines the risk for SSI as a
complication of surgery. Most of these
factors have been shown to be associated
with SSI; however, it is difficult to prove
an independent association between
every specific risk factor and SSI,
particularly when looking at different
groups of surgical patients (i.e., different
patient population, different procedures).
Risk Factors for Surgical Site Infection
According to the Three Main Determinants
of Such Infection
MICROORGANISM
Remote site infection
Long-term care facility
Recent hospitalization
Duration of the procedure
Wound class
Intensive care unit patient
Previous antibiotic
Preoperative shaving
Bacterial number, virulence,
and antimicrobial
resistance
LOCAL WOUND
PATIENT
Surgical technique
Age
Hematoma/seroma Immunosuppression
Necrosis
Steroids
Sutures
Malignancy
Drains
Obesity
Foreign bodies
Diabetes
Malnutrition
Multiple comorbid
conditions
Transfusions Cigarette
smoking Oxygen Temperature
Glucose control
Bacterial factors include virulence and
bacterial load in the surgical site. The
development of infection is affected by
the toxins produced by the
microorganism and the microorganism's
ability to resist phagocytes and
intracellular destruction.
Several bacterial species have surface
components that contribute to their
pathogenicity by inhibiting phagocytosis
(e.g., the capsules of Klebsiella and
Streptococcus pneumoniae, the slime of
coagulase-negative staphylococci).
Gram-negative bacteria have surface
components (endotoxin or
lipopolysaccharide) that are toxic, and
others, such as certain strains of
clostridia and streptococci, produce
powerful exotoxins that enable them to
establish invasive infection after smaller
inocula than needed for other pathogens
and to evolve much more rapidly.
Thus, although most wound infections do
not become clinically evident for 5 days
or longer after the operation,
streptococcal or clostridial infections may
become severe within 24 hours.
Studies of traumatic wounds in healthy
subjects have shown that bacterial
contamination with more than 105
organisms frequently causes infection
whereas contamination with less than 105
organisms usually does not, although βhemolytic streptococci can cause
infection with many fewer organisms.
The normal defense mechanisms are
therefore of great importance in
preventing infection at its inception, but
wound infection is inevitable if the
bacterial inoculum is sufficiently large.
This observation led, in the 1990s, to a
wound classification system in which
wounds are classified and presumed to
have different number and type of
bacteria according to the anatomic areas
entered and the aseptic and antiseptic
techniques used.
Length of preoperative stay, remote site
infection at the time of surgery, and
duration of the procedure have also been
associated with an increased bacterial
load and SSI rate. Preoperative shaving
has been shown to increase the incidence
of SSI after clean procedures as well.
This practice increases the infection rate
about 100% as compared with removing
the hair by clippers at the time of the
procedure or not removing it at all,
probably secondary to bacterial growth in
microscopic cuts. Therefore, the patient is
not shaved before an operation.
Extensive removal of hair is not needed,
and any hair removal that is done is
performed by electric clippers with
disposable heads at the time of the
procedure and in a manner that does not
traumatize the skin.
Surgical Wound Classification
According to Degree of contamination
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Clean
Clean-contaminated
Contaminated
Dirty
Clean
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An uninfected operative wound in which
no inflammation is encountered and the
respiratory, alimentary, genital, or
infected urinary tract is not entered.
Wounds are closed primarily and, if
necessary, drained with closed drainage.
Surgical wounds after blunt trauma
should be included in this category if they
meet the criteria
Clean-contaminated
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An operative wound in which the
respiratory, alimentary, genital, or urinary
tract is entered under controlled
conditions and without unusual
contamination
Contaminated
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Open, fresh, accidental wounds. In
addition, operations with major breaks in
sterile technique or gross spillage from
the gastrointestinal tract and incisions in
which acute, nonpurulent inflammation is
encountered are included in this category
Dirty
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Old traumatic wounds with retained
devitalized tissue and those that involve
existing clinical infection or perforated
viscera. This definition suggests that the
organisms causing postoperative
infection were present in the operative
field before the operation
Local wound factors are related to the
invasiveness of an operation and to
specific surgeon's practices and surgical
technique. The fact that an operation
breaks basic barrier defense mechanisms
such as skin and gastrointestinal mucosa
is a factor clearly associated with SSI.
Good surgical technique while managing
tissues (local wound) in the most
appropriate manner and using sutures,
drains, and foreign bodies only with
adequate indication is the best way to
avoid SSIs.
Patient-related factors include age,
immunosuppression, steroids,
malignancy, obesity, perioperative
transfusions, cigarette smoking, diabetes,
other preexisting illness, and
malnutrition, among others.
It is hard to perform a study in which
independent association with SSI can be
proved while controlling for all other
factors; however, patient-related factors
seem to play a very important role in SSI,
and preventive measures are starting to
focus on manipulating these factors, as
discussed later in this section.
Recent data suggest that maintaining
normothermia in the perioperative period
and delivering an FIO2 of 80% or higher in
the OR and postanesthesia care unit will
reduce the rate of SSI by improving O2
tension and white blood cell function in
the surgical incision.
In addition, data suggest that control of
glucose levels in the perioperative period
and up to 48 hours later in both diabetic
and nondiabetic patients can reduce rates
of SSI and decrease overall postoperative
mortality
Risk Scores for Surgical Site
Infection
SSI risk has traditionally been correlated
to wound class. The accepted range of
infection rates has been 1% to 5% for
clean, 3% to 11% for clean-contaminated,
10% to 17% for contaminated, and greater
than 27% for dirty wounds.
Risk Scores for Surgical Site
Infection
Wound class, as discussed earlier, is a
significant risk factor for SSI; however, it
assesses only the bacterial factors
related to wound infection and is thus an
imprecise method of including different
types of procedures and different kinds of
patients in one category.
More recently, the NNIS score, published
by Culver and associates in 1991 and
recently validated, includes additional
factors that have an independent
relationship with SSI. The NNIS score
includes the wound class, the American
Society of Anesthesiologists (ASA) class,
and the duration of the procedure in
comparison to national averages for the
same operation.
This combination of factors differentiates
the risk for SSI more accurately than the
previous wound classification system
does when used alone.
NNIS Score and Risk for SSI
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Risk Factors
Procedure time >75th percentile
Contaminated or dirty wound
ASA III, IV, V
NNIS Score and Risk for SSI
NUMBER OF POSITIVE
RISK FACTORS
0
1
2
3
RISK FOR SSI
1.5%
2.9%
6.8%
13.0%
NNIS Score and Risk for SSI
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ASA, American Society of
Anesthesiologists class;
NNIS, National Nosocomial Infection
Surveillance;
SSI, surgical site infection.
Comparison of NNIS Score and
Wound Classification for
Predicting Risk for SSI
NNIS RISK SCORE
WOUND CLASS
0 1
2
3
All
Clean
1.0 2.3 5.4 —
2.1
Clean-contaminated 2.1 4.0 9.5 —
3.3
Contaminated
— 3.4 6.8 13.2 6.4
Dirty
— 3.1 8.1 12.8 7.1
All
1.5 2.9 6.8 13.0 —
Prevention
Understanding risk factors and preventive
measures promotes better control with
lower infection rates. Two milestones in
preventing SSI have been defined by
specific preventive measures: first, the
aseptic and antiseptic technique
introduced by Lister and, second, the
proper use of prophylactic antibiotics.
Prevention
A third milestone is currently being
defined by practices that optimize and
maximize the patient's own ability to
prevent infection. Microorganisms are a
necessary part of the human
microenvironment, and even clean
wounds have small numbers of bacteria
present at the end of the operation.
Prevention
Most of the early preventive measures
implemented were focused on controlling
the bacterial factors for wound infection.
In recent years research has focused on
manipulating host (patient) factors to
assist the body in dealing with fixed
bacterial factors (assuming that all
preventive measures have been applied
appropriately).
Prevention
The future in the control of infection will
focus on patient factors and the body's
ability to counteract the obligatory
presence of microorganisms.
Prevention
Finally, as we practice in the era of health
care management and quality assurance,
an additional and recently emphasized
key component in preventing SSI has
become the ability to implement and
translate known preventive measures into
everyday practice.
Prevention
Preventive measures can be also
classified according to the three
determinants of wound infection and the
timing at which the measures are
implemented (preoperatively,
intraoperatively, and postoperatively)
Preventive Measures for Surgical
Site Infection

DETERMINANT IN WHICH THE
PREVENTIVE MEASURE ACTS
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–
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Preoperative
Intraoperative
Postoperative
Preoperative

Microorganism
Shorten preoperative stay
Antiseptic shower preoperatively
Appropriate preoperative hair removal or
no hair removal
Avoid or treat remote site infections
Antimicrobial prophylaxis
Preoperative

Local
Appropriate preoperative hair removal
or no hair removal
Preoperative

Patient
Optimize nutrition
Preoperative warming
Tight glucose control (insulin drip)
Stop smoking
Intraoperative

Microorganism
Asepsis and antisepsis
Avoid spillage in gastrointestinal cases
Intraoperative
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Local
Surgical technique:
Hematoma/seroma
Good perfusion
Complete débridement
Dead spaces
Monofilament sutures
Justified drain use (closed)
Limit use of sutures/foreign bodies
Delayed primary closure when indicated
Intraoperative

Patient
Supplemental oxygen
Intraoperative warming
Adequate fluid resuscitation
Tight glucose control (insulin drip)
Postoperative

Microorganism
Protect incision for 48-72 hours
Remove drains as soon as possible
Avoid postoperative bacteremia
Postoperative

Local
Postoperative dressing for 48-72 hours
Postoperative

Patients
Early enteral nutrition
Supplemental oxygen
Tight glucose control (insulin drip)
Surveillance programs
Microorganism Related
Microorganisms causing SSI can be either
exogenous or endogenous. Exogenous
microorganisms come from the operating
team or from the environment around the
surgical site (OR, equipment, air, water,
and so on).
Microorganism Related
Endogenous microorganisms come either
from the bacteria present in the patient at
the surgical site or from bacteria present
at a different location (e.g., remote site
infection, nasal colonization). Two
primary measures exist to control the
bacterial load in the surgical site: aseptic
and antiseptic methods and antimicrobial
prophylaxis.
Aseptic and Antiseptic Methods
Specific environmental and architectural
characteristics of the OR help reduce the
bacterial load in the OR itself, although it
has not been proved to decrease the
incidence of SSI, except in refined clean
procedures such as joint replacement.
Aseptic and Antiseptic Methods
Basic principles include size of the OR,
air management (filtered flow, positive
pressure toward the outside, and air
cycles per hour), equipment handling
(disinfection and cleansing), and traffic
rules. All OR personnel wear clean
scrubs, caps, and masks, and traffic in
and out of the OR is minimized.
Aseptic and Antiseptic Methods
Exogenous sources of bacteria causing
SSI are rare when standard measures are
followed and are important only in cases
of outbreaks, such as those that follow
failure of sterilization procedures or are
traced to OR personnel who shed
bacteria.
Aseptic and Antiseptic Methods
Specific air-filtering mechanisms and other
high-tech measures for environmental control
in the OR play a significant role in wound
infection control only in clean cases in which
prostheses are implanted. However, a
minimum of basic traffic, environment, and
OR behavior rules is followed by staff in the
surgical pool as part of a discipline that keeps
the team aware of potential causes of
infection in surgical patients
Aseptic and Antiseptic Methods
Surgical site preparation, on the other
hand, is an important measure in
preventing SSI. Preoperative showers the
night before surgery with chlorhexidine
have not been shown to affect the
frequency of SSI, although they do reduce
the bacterial colony count on skin.
Aseptic and Antiseptic Methods
The CDC recommends the use of
chlorhexidine showers, and it is
reasonable to implement such a policy,
particularly in patients who have been in
the hospital for a few days and in those in
whom an SSI will cause significant
morbidity (cardiac, vascular, and
prosthetic procedures).
Aseptic and Antiseptic Methods
Skin preparation of the surgical site is
done with a germicidal antiseptic such as
tincture of iodine, povidone-iodine, or
chlorhexidine. An alternative preparation
is the use of antimicrobial incise drapes
applied to the entire operative area.
Traditionally, the surgical team has
scrubbed their hands and forearms for at
least 5 minutes the first time in the day
and for 3 minutes every consecutive time.
Aseptic and Antiseptic Methods
Popular antiseptics used are povidoneiodine and chlorhexidine. Recent data
have shown that the use of alcohol hand
rub solutions is as effective as the
aforementioned antiseptics while being
faster and kinder to the skin of the
surgical team. The use of sterile drapes
and gowns is a way of maintaining every
surface in contact with the surgical site as
sterile as possible.
Aseptic and Antiseptic Methods
As many as 90% of an operative team
puncture their gloves during a prolonged
operation. The risk increases with time, as
does the risk for contamination of the
surgical site if the glove is not changed at
the moment of puncture. The use of
double gloving is becoming a popular
practice to avoid contamination of the
wound, as well as exposure to blood by
the surgical team.
Aseptic and Antiseptic Methods
Double gloving is recommended for all
surgical procedures. Instruments that will
be in contact with the surgical site are
sterilized in standard fashion, and
protocols for flash sterilization or
emergency sterilization, or both, must be
well established to ensure the sterility of
instruments and implants.
Antimicrobial Prophylaxis
Systemic antimicrobial prophylaxis is a
potentially powerful preventive measure
for SSI that is frequently delivered in an
ineffective manner, more because of lack
of a reliable process in the hospital and
operating room than because of lack of
understanding.
Antimicrobial Prophylaxis
Experience has shown that the
effectiveness of antibiotic prophylaxis
depends on an organized system to
ensure its delivery in an effective manner.
If a system is not in place, the results are
haphazard failures.
Antimicrobial Prophylaxis
Recent national surveys have
documented suboptimal prophylactic
antibiotic use in 40% to 50% of operative
procedures. It is clear that the
administration of therapeutic doses of
antimicrobial agents can prevent infection
in wounds contaminated by bacteria
sensitive to the agents.
Antimicrobial Prophylaxis
The decision to use prophylactic
antibiotic therapy, however, must be
based on balancing possible benefit
against possible adverse effects.
Indiscriminate use of antibiotics is
discouraged because it may lead to the
emergence of antibiotic-resistant strains
of organisms or serious hypersensitivity
reactions.
Antimicrobial Prophylaxis
In particular, prolonged use of
prophylactic antibiotics may also mask
the signs of established infections, thus
making diagnosis more difficult and
causing an increase in the number of
resistant pathogens recovered from
surgical patients.
Antimicrobial Prophylaxis
Prophylactic systemic antibiotics are not
indicated for patients undergoing lowrisk, straightforward clean surgical
operations in which no obvious bacterial
contamination or insertion of a foreign
body has occurred.
Antimicrobial Prophylaxis
When the incidence of wound infections
is less than 1% and the consequences of
SSI are not severe, the potential for
reducing this low infection rate does not
justify the expense and side effects of
antibiotic administration.
Antimicrobial Prophylaxis
Prophylactic antibiotic therapy is no
substitute for careful surgical technique
using established surgical principles, and
indiscriminate or general use of
prophylactic therapy is not in the best
interest of the patient. Antibiotic agents
can be used effectively only as adjuncts
to adequate surgery.
Antimicrobial Prophylaxis
In several clinical situations the
administration of prophylactic systemic
antibiotic therapy is usually beneficial.
Such situations almost always involve a
brief period of contamination by
organisms that can be predicted with
reasonable accuracy. As examples,
prophylactic systemic antibiotics reduce
infection and are clinically beneficial in
the following circumstances:
Antimicrobial Prophylaxis
1. High-risk gastroduodenal procedures,
including operations for gastric cancer,
ulcer, obstruction, or bleeding; operations
when gastric acid production has been
suppressed effectively; and gastric
operations for morbid obesity
Antimicrobial Prophylaxis
2. High-risk biliary procedures,
including operations in patients older
than 60 years and those for acute
inflammation, common duct stones, or
jaundice and in patients with previous
biliary tract operations or endoscopic
biliary manipulation
Antimicrobial Prophylaxis
3. Resection and anastomosis of the
colon or small intestine (see later)
4. Cardiac procedures through a median
sternotomy
Antimicrobial Prophylaxis
5. Vascular surgery of the lower
extremities or abdominal aorta
6. Amputation of an extremity with
impaired blood supply, particularly in the
presence of a current or recent ischemic
ulcer
7. Vaginal or abdominal hysterectomy
Antimicrobial Prophylaxis
8.
9.
Primary cesarean section
Operations entering the oral
pharyngeal cavity
10. Craniotomy
11. Implantation of any permanent
prosthetic material
12. Any wound with known gross
bacterial contamination
Antimicrobial Prophylaxis
13. Accidental wounds with heavy
contamination and tissue damage. In
such instances the antibiotic is given
intravenously as soon as possible after
injury. The two best-studied situations are
penetrating abdominal injuries and open
fractures
Antimicrobial Prophylaxis
14. Injuries prone to clostridial infection
because of extensive devitalization of
muscle, heavy contamination, or
impairment of the blood supply
Antimicrobial Prophylaxis
Whether prophylactic antibiotics are
given for so-called clean operations not
involving the implantation of prosthetic
materials has been controversial. A welldesigned trial demonstrated a reduction
in infection risk when patients undergoing
breast procedures or groin hernia repairs
received prophylactic antibiotics versus
placebo.
Antimicrobial Prophylaxis
However, these procedures are not
universally considered valid indications
for prophylaxis. Some have proposed that
such clean operations with one or more
NNIS risk points be considered for
prophylactic antibiotic administration.
Antimicrobial Prophylaxis
Administration of oral nonabsorbable
antibiotics to suppress both aerobic and
anaerobic intestinal bacteria before
scheduled operations on the colon has
also been successful in controlled trials.
Neomycin plus erythromycin given only
on the day before surgery, 19, 18, and 9
hours before the scheduled start of the
procedure, is the most well-established
combination at the present time.
Antimicrobial Prophylaxis
Neomycin plus metronidazole is also an
effective combination. Thorough
mechanical cleansing of the intestinal
tract is an important component of the
oral regimen. Controversies regarding the
benefit of mechanical and oral
antimicrobial bowel preparation have
recently resurfaced.
Antimicrobial Prophylaxis
Multiple meta-analyses have shown no
effect of mechanical bowel preparation on
the incidence of SSI in the absence of oral
antibiotics, and some have shown an
increased incidence of anastomotic leaks,
thus questioning its true benefit even
more.
Antimicrobial Prophylaxis
However, several reports demonstrated a
reduced infection rate with the
combination of oral nonabsorbable and
intravenous antibiotics, and this is the
most common practice among colorectal
surgeons in the United States. Future
recommendations regarding this practice
may well change over the next few years.
Antimicrobial Prophylaxis
Prophylactic antibiotic therapy is clearly
more effective when begun preoperatively
and continued through the intraoperative
period, with the aim of achieving
therapeutic blood levels throughout the
operative period. This produces
therapeutic levels of antibiotic agents at
the operative site in any seromas and
hematomas that may develop.
Antimicrobial Prophylaxis
Antibiotics started as late as 1 to 2 hours
after bacterial contamination are markedly
less effective, and it is completely without
value to start prophylactic antibiotics
after the wound is closed.
Antimicrobial Prophylaxis
Failure of prophylactic antibiotic agents
occurs in part through neglect of the
importance of the timing and dosage of
these agents, which are critical
determinants.
Antimicrobial Prophylaxis
For most patients undergoing elective
surgery, the first dose of prophylactic
antibiotics are given intravenously at the
time that anesthesia is induced. It is
unnecessary and may be detrimental to
start them more than 1 hour
preoperatively, and it is unnecessary to
give them after the patient leaves the
operating room.
Antimicrobial Prophylaxis
A single dose, depending on the drug
used and length of the operation, is often
sufficient. For operations that are
prolonged, the prophylactic agent chosen
is given in repeated doses at intervals of
one to two half-lives for the drug being
used. Prophylactic antibiotic coverage for
more than 12 hours for a planned
operation is never indicated.
Antimicrobial Prophylaxis
In addition, for obese patients there are
studies showing benefit of higher initial
doses and more frequently repeated
doses (including continuous antibiotic
drips) to achieve appropriate tissue levels
throughout the operation.
Antimicrobial Prophylaxis
No evidence supports the practice of
continuing prophylactic antibiotics until
central lines, drains, and chest tubes are
removed. There is evidence, however, that
this practice increases the recovery of
resistant bacteria.
Antimicrobial Prophylaxis
Many patients fail to receive needed
prophylactic antibiotics because the
system for their administration is complex
at the time of multiple events just before a
major operation.
Antimicrobial Prophylaxis
This problem has been made worse by the
trend of admitting patients directly to the
operating room for planned operations,
which intensifies the pressure to
accomplish a large number of procedures
during a short interval before the
operation. The possibility that prophylactic
antibiotics will unintentionally be omitted
can be minimized by establishing a system
with a checklist.
Antimicrobial Prophylaxis
One member of the operative team
(usually the preoperative nurse or a
member of the anesthesia team) is
responsible for initialing a portion of the
operative record that states either that the
patient received indicated prophylactic
antibiotics or that the surgeon has
determined that antibiotics are not
indicated for the procedure.
Antimicrobial Prophylaxis
Many antibiotics effectively reduce the
rate of postoperative SSI when used
appropriately for indicated procedures.
No antibiotic has been reliably superior to
another when each possessed a similar
and appropriate antibacterial spectrum.
Antimicrobial Prophylaxis
The most important determinant is
whether the planned procedure is
expected to enter parts of the body known
to harbor obligate colonic anaerobic
bacteria (Bacteroides species). If
anaerobic flora are anticipated, such as
during operations on the colon or distal
ileum or during appendectomy, an agent
effective against Bacteroides species,
such as cefotetan, must be used.
Antimicrobial Prophylaxis
Cefoxitin is an alternative with a
dramatically shorter half-life. Cefazolin
combined with metronidazole is another
alternative choice. If anaerobic flora are
not expected, cefazolin is the prophylactic
drug of choice.
Antimicrobial Prophylaxis
For patients who are allergic to
cephalosporins, clindamycin or, in
settings in which methicillin-resistant S.
aureus (MRSA) is common, vancomycin
can be used. Prophylactic use of
vancomycin is minimized as much as
possible to reduce environmental
pressure favoring the emergence of
vancomycin-resistant enterococci and
staphylococci.
Antimicrobial Prophylaxis
If an intestinal procedure is planned in
such an allergic patient, a regimen with
activity against gram-negative rods and
anaerobes must be used, such as an
aminoglycoside or a fluoroquinolone
combined with clindamycin or
metronidazole or aztreonam combined
with clindamycin.
Antimicrobial Prophylaxis
The use of topical antibiotics often
effectively diminishes the incidence of
infection in contaminated wounds.
However, the combination of topical
agents and parenteral agents is not more
effective than either one alone, and
topical agents alone are inferior to
parenteral agents in complex gastric
procedures.
Antimicrobial Prophylaxis
As a general rule, topical agents do not
cause any harm if one adheres to the
following rules:
1. Do not use any agent in wounds or in
the abdomen that would not be suitable
for parenteral adminis-tration.
2. Do not use more of the agent than
would be acceptable for parenteral
administration.
Antimicrobial Prophylaxis
In considering the amount used, any drug
being given parenterally must be added to
the amount being placed in the wound.
Topical agents used for burn wounds
(discussed elsewhere) may be used in
large open wounds in selected patients.
Antimicrobial Prophylaxis
Prophylactic antibiotic therapy is
generally ineffective in clinical situations
in which continuing contamination is
likely to occur.
Antimicrobial Prophylaxis
Examples follow:
1.
In patients with tracheostomies or tracheal
intubation to prevent pulmonary infections
2. In patients with indwelling urinary catheters
3. In patients with indwelling central venous
lines
4. In patients with wound or chest drains
5. In most open wounds, including burn wounds
Local Wound Related
Most of the preventive measures related
to the local wound are determined by the
good judgment and surgical technique of
the surgeon. Intraoperative measures
include appropriate handling of tissue
and assurance of satisfactory final
vascular supply, but with adequate
control of bleeding to prevent
hematomas/seromas.
Local Wound Related
Complete débridement of necrotic tissue
plus removal of unnecessary foreign
bodies is recommended, as well as
avoiding the placement of foreign bodies
in clean-contaminated, contaminated, or
dirty cases. Monofilament sutures have
proved in experimental studies to be
associated with a lower rate of SSI.
Sutures are foreign bodies that are used
only when required.
Local Wound Related
Suture closure of dead space has not been
shown to prevent SSI. Large potential dead
spaces can be treated with the use of closedsuction systems for short periods, but these
systems provide a route for bacteria to reach
the wounds and may cause SSI. Open
drainage systems (e.g., Penrose) increase
rather than decrease infections in surgical
wounds and are avoided unless used to drain
wounds that are already infected.
Local Wound Related
In heavily contaminated wounds or
wounds in which all the foreign bodies or
devitalized tissue cannot be satisfactorily
removed, delayed primary closure
minimizes the development of serious
infection in most instances. With this
technique, the subcutaneous tissue and
skin are left open and dressed loosely
with gauze after fascial closure.
Local Wound Related
The number of phagocytic cells at the
wound edges progressively increases to a
peak about 5 days after the injury.
Capillary budding is intense at this time,
and closure can usually be accomplished
successfully even with heavy bacterial
contamination because phagocytic cells
can be delivered to the site in large
numbers.
Local Wound Related
Experiments have shown that the number
of organisms required to initiate an
infection in a surgical incision
progressively increases as the interval of
healing increases, up to the fifth
postoperative day.
Local Wound Related
Finally, adequate dressing of the closed
wound isolates it from the outside
environment. Providing an appropriate
dressing for 48 to 72 hours can decrease
wound contamination. However,
dressings after this period increase the
subsequent bacterial count on adjacent
skin by altering the microenvironment
underneath the dressing.
Patient Related
Host resistance is abnormal in a variety of
systemic conditions and diseases,
including leukemia, diabetes mellitus,
uremia, prematurity, burn or traumatic
injury, advanced malignancy, old age,
obesity, malnutrition, and several
diseases of inherited immunodeficiency.
Patient Related
In surgical patients who have these or
similar problems, extra precautions are
taken to prevent the development of
wound infections, including correction or
control of the underlying defect whenever
possible.
Patient Related
Malnutrition and low albumin levels are
associated with an increased rate of SSI.
Optimizing nutritional status before
surgery and early in the postoperative
periods with specific immunonutrition
(arginine, nucleotides, ω-3 fatty acids)
formulas may decrease the incidence of
SSI in patients with upper gastrointestinal
tract cancer
Patient Related
Recent studies have also demonstrated
that maintaining a higher partial pressure
of oxygen by delivering a higher inspired
fraction of oxygen with adequate fluid
resuscitation is associated with a
decreased rate of SSI. The presumed
mechanism is more oxygen available for
white blood cells to kill bacteria present in
the wound at the time of the operation.
Patient Related
Preoperative warming was also
demonstrated in two recent prospective
randomized controlled trials to reduce SSI
rates. Other studies have shown that
increasing tissue temperature by 4°C
results in increased perfusion and oxygen
delivery to the incision.
Patient Related
Finally, in critically ill patients, aggressive
perioperative insulin therapy with the use
of insulin drips to maintain glucose levels
between 80 and 110 mg/dL was
associated with decreased mortality in
this set of patients.
Patient Related
Other studies of patients undergoing
cardiac and gastrointestinal surgery have
demonstrated an increased rate of SSI
when perioperative blood glucose levels
exceeded 200 mg/dL, regardless of
whether the patients were diabetic.
System-Based Prevention
The need for efficient resource utilization
and cost containment, as well as the new
era of managed health care and quality
assurance, has raised new interest in the
prevention of SSI. Recently, delivery
processes for preventive strategies have
been studied and shown to be well under
ideal standards. The most illustrative
example has been the use of prophylactic
antibiotics.
System-Based Prevention
The Surgical Infection Prevention Project
(SIPP)—a national effort led by the Center
for Medicare and Medicaid Services (CMS)
to achieve lower rates of SSI—showed
that in more than 32,000 surgical
procedures performed in different centers
around the United States, only 55.7% of
patients were given prophylactic
antibiotics within 1 hour of the incision
time.
System-Based Prevention
A collaborative (the SIPP Collaborative)
was created to maximize delivery of this
preventive strategy through educational
and system-related changes, among
others. The project was carried out over a
12-month period in more than 50 U.S.
hospitals, and the timing of antibiotic
prophylaxis, as well as other measures,
improved significantly, with a relative 27%
reduction in SSIs being achieved.
System-Based Prevention
This constitutes a good example of the
current system-related obstacles in
controlling SSI and a method to overcome
the problem and is one of many other
models to follow as part of the strategy to
decrease the incidence of SSI.
The CMS has recently begun to alter and
make payment rates dependent on
hospitals reporting their success in this
and other preventive measures.
System-Based Prevention
It is the modern surgeon's responsibility,
as the leader of the surgical delivery
system, to implement all known and
proven measures that reduce the
incidence of SSI.
System-Based Prevention
Wound infection surveillance systems
have proved to be an important measure
in controlling SSI rates, and perhaps this
is achieved by permanent and continuous
awareness by surgeons and surgical
teams of the risk and the measures that
can be used to avoid this common
complication.
System-Based Prevention
Surveillance of SSI includes a
determination for each SSI of whether all
accepted preventive measures were
provided for that patient and procedure. If
they were not, the SSI can be classified as
potentially preventable. If all appropriate
preventive measures were provided, the
SSI is apparently unpreventable.
System-Based Prevention
The goal of surgical practice and
surveillance is to have no potentially
preventable SSI. As our knowledge
regarding SSI prevention increases, the
definition of potentially preventable could
expand.
Treatment
Treatment of SSI follows standard
principles of management for all surgical
infections, as explained later. In general,
the mainstay of treatment is source
control or draining of the infected area.
For a superficial SSI this involves opening
the wound at the skin and subcutaneous
levels and cleansing the wound, along
with dressing changes twice or three
times a day.
Treatment
Occasionally, sharp débridement to allow
healing of the open wound is necessary.
Once the wound infection has been
controlled, wound-suctioning devices can
also be used to minimize the discomfort
from more frequent dressing changes and
possibly to accelerate wound healing. For
organ/procedure-related SSI, source
control can generally be achieved with
percutaneous drainage.
Treatment
It is imperative to ensure that the infection
is well controlled with percutaneous
drainage; if it involves a more diffuse area
of a human cavity (i.e., diffuse peritonitis,
mediastinitis), surgical drainage is
encouraged and would include repair of
any anatomic cause of infection (e.g.,
anastomotic leak) if present.
Treatment
The use of antibiotics is not the standard
for treatment of incisional SSI. They are
recommended only as adjunctive therapy
when surrounding cellulitis occurs or
when treating a deep SSI
(organ/procedure related).
Thank you for your attention!