Transcript intra-abdominal infection

In the name of God
Infections of Significance in Surgical Patients
 Present by:
Mostafa Ahani
Surgical Site Infections
 SSIs are infections of the tissues, organs, or spaces exposed
by surgeons during performance of an invasive procedure.
SSIs are classified into incisional and organ/space infections,
and the former are further subclassified into superficial
(limited to skin and subcutaneous tissue) and deep incisional
categories.35 The development of SSIs is related to three
factors: (a) the degree of microbial contamination of the
wound during surgery, (b) the duration of the procedure, and
(c) host factors such as diabetes, malnutrition, obesity,
immune suppression, and a number of other underlying
disease states. Table 6-7 lists risk factors for development of
SSIs. By definition, an incisional SSI has occurred if a
surgical wound drains purulent material or if the surgeon
judges it to be infected and opens it.
Risk Factors:
Cont…
 Surgical wounds are classified based on the presumed
magnitude of the bacterial load at the time of surgery (Table
6-8).36 Clean wounds (class I) include those in which no
infection is present; only skin microflora potentially
contaminate the wound, and no hollow viscus that contains
microbes is entered. Class ID wounds are similar except that
a prosthetic device (e.g., mesh or valve) is inserted.
Clean/contaminated wounds (class II) include those in which
a hollow viscus such as the respiratory, alimentary, or
genitourinary tracts with indigenous bacterial flora is opened
under controlled circumstances without significant spillage of
contents. Interestingly, while elective colorectal cases have
classically been included as class II cases, a number of
studies in the last decade have documented higher SSI rates
(9 to 25%).37–39 One study identified two thirds of infections
presenting after discharge from hospital, highlighting the
need for careful follow-up of these patients.
Cont…
 Infection is also more common in cases involving entry into the
rectal space.39 Contaminated wounds (class III) include open
accidental wounds encountered early after injury, those with
extensive introduction of bacteria into a normally sterile area of the
body due to major breaks in sterile technique (e.g., open cardiac
massage), gross spillage of viscus contents such as from the
intestine, or incision through inflamed, albeit nonpurulent, tissue.
Dirty wounds (class IV) include traumatic wounds in which a
significant delay in treatment has occurred and in which necrotic
tissue is present, those created in the presence of overt infection as
evidenced by the presence of purulent material, and those created
to access a perforated viscus accompanied by a high degree of
contamination. The microbiology of SSIs is reflective of the initial
host microflora such that SSIs following creation of a class I wound
are invariable, due solely to skin microbes found on that portion of
the body, while SSIs subsequent to a class II wound created for the
purpose of elective colon resection may be caused by either skin
microbes or colonic microflora, or both.
Cont…
 In the United States, hospitals are required to conduct surveillance
for the development of SSIs for a period of 30 days after the
operative procedure.40 Such surveillance has been associated with
greater awareness and a reduction in SSI rates, probably in large
part based upon the impact of observation and promotion of
adherence to appropriate care standards. Several different SSI risk
stratification schemes have been developed via retrospective,
multivariate analysis of large surveillance data sets. The National
Nosocomial Infection Surveillance (NNIS) risk index is commonly
used and assesses three factors: (a) American Society of
Anesthesiologists Physical Status score greater than 2, (b) class
III/IV wound, and (c) duration of operation greater than the 75th
percentile for that particular procedure, to refine the risk of infection
beyond that achieved by use of wound classification alone.
Intriguingly, the risk of SSIs for class I wounds varies from
approximately 1 to 2% for patients with low NNIS scores, to
approximately 15% for patients with high NNIS scores (e.g., long
operations and/or high American Society of Anesthesiologists
scores), and it seems clear that additional refinements are
required.41
Classification
Cont…
 SSIs are associated with considerable morbidity and occasional
lethality, as well as substantial health care costs and patient
inconvenience and dissatisfaction.42 For that reason, surgeons
strive to avoid SSIs by using the maneuvers described in the
previous section Prevention and Treatment of Surgical Infections.
Also, the use of prophylactic antibiotics may serve to reduce the
incidence of SSI rates during certain types of procedures. For
example, it is well accepted that a single dose of an antimicrobial
agent should be administered immediately before commencing
surgery for class ID, II, III, and IV types of wounds.43It seems
reasonable that this practice should be extended to patients in any
category with high NNIS scores, although this remains to be proven.
Thus the utility of prophylactic antibiotics in reducing the rate of
wound infection subsequent to clean surgery remains controversial,
and these agents should not be used under routine circumstances
(e.g., in healthy young patients). However, because of the potential
dire consequences of a wound infection after clean surgery in which
prosthetic material is implanted into tissue, patients who undergo
such procedures should receive a single preoperative dose of an
antibiotic.
Cont…
Surgical management of the wound is also a critical determinant of the
propensity to develop an SSI. In healthy individuals, class I and II wounds may
be closed primarily, while skin closure of class III and IV wounds is associated
with high rates of incisional SSIs (approximately 25 to 50%). The superficial
aspects of these latter types of wounds should be packed open and allowed to
heal by secondary intention, although selective use of delayed primary closure
has been associated with a reduction in incisional SSI rates.46 It remains to be
determined whether NNIS-type stratification schemes can be used
prospectively to target specific subgroups of patients who will benefit from the
use of prophylactic antibiotic and/or specific wound management techniques.
One clear example based on cogent data from clinical trials is that class III
wounds in healthy patients undergoing appendectoy for perforated or
gangrenous appendicitis can be primarily closed as long as antibiotic therapy
directed against aerobes and anaerobes is administered. This practice leads to
SSI rates of approximately 3 to 4%.47
Cont…
 Recent investigations have studied the effect of
additional maneuvers in an attempt to further
reduce the rate of SSIs. The adverse effects of
hyperglycemia on WBC function have been well
described.48 A number of recent studies have
reported the effects of hyperglycemia in vivo in
diabetic patients, with increased SSI rates being
associated with hyperglycemia in cardiac surgery
patients undergoing bypass.49,50 On this basis, it is
recommended that clinicians maintain appropriate
blood sugar control in diabetic patients in the
perioperative period to minimize the occurrence of
SSIs.
Cont…
 The effects of the level of inhaled oxygen and prewarming of
the wound on SSI rates also have been studied. Although an
initial study provided evidence that patients who received
high levels of inhaled oxygen during colorectal surgery
developed fewer SSIs,51 data to the contrary recently have
been reported.52,53 In another study, preoperative warming of
the wound site for 30 minutes before surgery among patients
undergoing clean surgery was associated with a decrease in
SSIs (5% with warmed wounds vs. 14% without).54
Unfortunately, several of the aforementioned studies report
SSI rates among study patients that are higher than those
reported and expected among similar groups of patients,
making comparison difficult. Of note, stratification using the
NNIS classification methodology was not used. Further
evaluation via multicenter studies is needed before
implementation of these modalities as standard therapies.
Cont…
 Effective therapy for incisional SSIs consists solely of incision and
drainage without the addition of antibiotics. Antibiotic therapy is
reserved for patients in whom evidence of significant cellulitis is
present, or who manifest concurrent SIRS. The open wound often is
allowed to heal by secondary intention, with dressings being
changed twice a day. The use of topical antibiotics and antiseptics
to further wound healing remains unproven, although anecdotal
studies indicate their potential utility in complex wounds that do not
heal with routine measures.55 Despite a paucity of prospective
studies,56 vacuum-assisted closure is increasingly used in
management of problem wounds and can be applied to complex
wounds in difficult locations (Fig. 6-2). Although culture results are
of epidemiologic interest, they rarely serve to direct therapy
because antibiotics are not routinely withheld until results are
known. The treatment of organ/space infections is discussed in
Intra-Abdominal Infections, below.
Intra-Abdominal Infections
 Microbial contamination of the peritoneal cavity is termed peritonitis or intraabdominal infection, and is classified according to etiology. Primary microbial
peritonitis occurs when microbes invade the normally sterile confines of the
peritoneal cavity via hematogenous dissemination from a distant source of
infection or direct inoculation. This process is more common among patients
who retain large amounts of peritoneal fluid due to ascites, and in those
individuals who are being treated for renal failure via peritoneal dialysis.
These infections invariably are monomicrobial and rarely require surgical
intervention. The diagnosis is established based on a patient who has
ascites for medical reasons, physical examination that reveals diffuse
tenderness and guarding without localized findings, absence of
pneumoperitoneum on abdominal flat plate and upright roentgenograms, the
presence of more than 100 WBCs/mL, and microbes with a single
morphology on Gram's stain performed on fluid obtained via paracentesis.
Subsequent cultures will typically demonstrate the presence of gram-positive
organisms in patients receiving peritoneal dialysis. In patients without this
risk factor organisms can include E. coli, K. pneumoniae, pneumococci, and
others, although many different pathogens can be causative. Treatment
consists of administration of an antibiotic to which the organism is sensitive;
often 14 to 21 days of therapy are required. Removal of indwelling devices
(e.g., peritoneal dialysis catheter or peritoneovenous shunt) may be required
for effective therapy of recurrent infections.
Cont…
 Secondary microbial peritonitis occurs subsequent to contamination
of the peritoneal cavity due to perforation or severe inflammation
and infection of an intra-abdominal organ. Examples include
appendicitis, perforation of any portion of the GI tract, or
diverticulitis. As noted previously in Source Control, effective
therapy requires source control to resect or repair the diseased
organ; débridement of necrotic, infected tissue and debris; and
administration of antimicrobial agents directed against aerobes and
anaerobes.57 This type of antibiotic regimen should be chosen
because in most patients the precise diagnosis cannot be
established until exploratory laparotomy is performed, and the most
morbid form of this disease process is colonic perforation, due to
the large number of microbes present. A combination of agents or
single agents with a broad spectrum of activity can be used for this
purpose; conversion of a parenteral to an oral regimen when the
patient's ileus resolves will provide results similar to those achieved
with IV antibiotics.58 Effective source control and antibiotic therapy is
associated with low failure rates and a mortality rate of
approximately 5 to 6%; inability to control the source of infection
leads to mortality greater than 40%.59
Cont…
 Formerly, the presence of an intra-abdominal abscess mandated
surgical re-exploration and drainage. Today, the vast majority of
such abscesses can be effectively diagnosed via abdominal
computed tomographic (CT) imaging techniques and drained
percutaneously. Surgical intervention is reserved for those
individuals who harbor multiple abscesses, those with abscesses in
proximity to vital structures such that percutaneous drainage would
be hazardous, and those in whom an ongoing source of
contamination (e.g., enteric leak) is identified. The necessity of
antimicrobial agent therapy and precise guidelines that dictate
duration of catheter drainage have not been established. A short
course (3 to 7 days) of antibiotics that possess aerobic and
anaerobic activity seems reasonable, and most practitioners leave
the drainage catheter in situ until it is clear that cavity collapse has
occurred, output is less than 10 to 20 mL/d, no evidence of an
ongoing source of contamination is present, and the patient's clinical
condition has improved.
Organ-Specific Infections
 Hepatic abscesses are rare, currently accounting for approximately 15 per
100,000 hospital admissions in the United States. Pyogenic abscesses
account for approximately 80% of cases, the remaining 20% being equally
divided among parasitic and fungal forms.63 Formerly, pyogenic liver
abscesses were caused by pylephlebitis due to neglected appendicitis or
diverticulitis. Today, manipulation of the biliary tract to treat a variety of
diseases has become a more common cause, although in nearly 50% of
patients no cause is identified. The most common aerobic bacteria identified
in recent series include E. coli, K. pneumoniae, and other enteric bacilli,
enterococci, and Pseudomonas spp., while the most common anaerobic
bacteria are Bacteroides spp., anaerobic streptococci, and Fusobacterium
spp. C. albicans and other similar yeasts cause the majority of fungal hepatic
abscesses. Small (<1 cm), multiple abscesses should be sampled and
treated with a 4- to 6-week course of antibiotics. Larger abscesses invariably
are amenable to percutaneous drainage, with parameters for antibiotic
therapy and drain removal similar to those mentioned above in IntraAbdominal Infections. Splenic abscesses are extremely rare and are treated
in a similar fashion. Recurrent hepatic or splenic abscesses may require
operative intervention—unroofing and marsupialization or splenectomy,
respectively.
Cont…
 Secondary pancreatic infections (e.g., infected pancreatic necrosis
or pancreatic abscess) occur in approximately 10 to 15% of patients
who develop severe pancreatitis with necrosis. The surgical
treatment of this disorder was pioneered by Bradley and Allen, who
noted significant improvements in outcome for patients undergoing
repeated pancreatic débridement of infected pancreatic necrosis.64
Current care of patients with severe acute pancreatitis includes
staging with dynamic, contrast-enhanced helical CT scan with 3-mm
tomographs to determine the extent of pancreatic necrosis, coupled
with the use of one of several prognostic scoring systems. Patients
who exhibit significant pancreatic necrosis (grade greater than C,
Fig. 6-3) should be carefully monitored in the ICU and undergo
follow-up CT examination. A recent change in practice has been the
elimination of the routine use of prophylactic antibiotics for
prevention of infected pancreatic necrosis. Early results were
promising;65 however, several randomized multicenter trials have
failed to show benefit and three meta-analyses have confirmed this
finding.66–68
Contrast-enhanced computed tomographic scan of pancreas with severe pancreatic
necrosis. Note lack of IV contrast within the boggy pancreatic bed (large black
arrow).
Cont…
 In two small studies, enteral feedings initiated early, using
nasojejunal feeding tubes placed past the ligament of Treitz,
have been associated with decreased development of
infected pancreatic necrosis, possibly due to a decrease in
gut translocation of bacteria. Recent guidelines support the
practice of enteral alimentation in these patients, with the
addition of parenteral nutrition if nutritional goals cannot be
met by tube feeding alone.69,70
 The presence of secondary pancreatic infection should be
suspected in patients whose systemic inflammatory response
(fever, elevated WBC count, or organ dysfunction) fails to
resolve, or in those individuals who initially recuperate, only
to develop sepsis syndrome 2 to 3 weeks later. CT-guided
aspiration of fluid from the pancreatic bed for performance of
Gram's stain and culture analysis is of critical importance. A
positive Gram's stain or culture from CT-guided aspiration, or
identification of gas within the pancreas on CT scan,
mandate operative intervention.
Infections of the Skin and Soft Tissue
 Infections of the skin and soft tissue can be classified
according to whether surgical intervention is required. For
example, superficial skin and skin structure infections, such
as cellulitis, erysipelas, and lymphangitis, invariably are
effectively treated with antibiotics alone, although a search
for a local source of infection should be undertaken.
Generally, drugs that possess activity against the grampositive skin microflora that are causative are selected.
Furuncles or boils may drain spontaneously or require
surgical incision and drainage. Antibiotics are prescribed if
significant cellulitis is present or if cellulitis does not rapidly
resolve after surgical drainage. Commonly acquired
methicillin-resistant S. aureus infection should be suspected
if infection persists after treatment with adequate drainage
and antibiotics. These infections may require more
aggressive drainage and altered antimicrobial therapy.73
Cont…
 Patients at risk for these types of infections include
those who are elderly, immunosuppressed, or
diabetic; those who suffer from peripheral vascular
disease; or those with a combination of these
factors. The common thread among these host
factors appears to be compromise of the fascial
blood supply to some degree, and if this is coupled
with the introduction of exogenous microbes, the
result can be devastating. However, it is of note
that over the last decade, extremely aggressive
necrotizing soft tissue infections among healthy
individuals due to streptococci have been
described as well.
Cont…
 Aggressive soft tissue infections are rare, difficult to
diagnose, and require immediate surgical intervention plus
administration of antimicrobial agents. Failure to do so results
in an extremely high mortality rate (approximately 80 to
100%), and even with rapid recognition and intervention,
current mortality rates remain high, approximately 16 to
25%.74,75 Eponyms and classification in the past have been a
hodgepodge of terminology, such as Meleney's synergistic
gangrene, rapidly spreading cellulitis, gas gangrene, and
necrotizing fasciitis, among others. Today, it seems best to
delineate these serious infections based on the soft tissue
layer(s) of involvement (e.g., skin and superficial soft tissue,
deep soft tissue, and muscle) and the pathogen(s) that
causes them.76
Cont…
 Initially, the diagnosis is established solely upon a constellation of clinical
findings, not all of which are present in every patient. Not surprisingly,
patients often develop sepsis syndrome or septic shock without an obvious
cause. The extremities, perineum, and torso are most commonly affected, in
that order. Careful examination should be undertaken for an entry site such
as a small break or sinus in the skin from which grayish, turbid semipurulent
material ("dishwater pus") can be expressed, as well as for the presence of
skin changes (bronze hue or brawny induration), blebs, or crepitus. The
patient often develops pain at the site of infection that appears to be out of
proportion to any of the physical manifestations. Any of these findings
mandates immediate surgical intervention, which should consist of exposure
and direct visualization of potentially infected tissue (including deep soft
tissue, fascia, and underlying muscle) and radical resection of affected
areas. Radiologic studies should be undertaken only in patients in whom the
diagnosis is not seriously considered, as they delay surgical intervention and
frequently provide confusing information. Unfortunately, surgical extirpation
of infected tissue frequently entails amputation and/or disfiguring
procedures; however, incomplete procedures are associated with higher
rates of morbidity and mortality (Fig. 6-5).
Cont…
During the procedure, a Gram's stain should be performed on tissue
fluid. Antimicrobial agents directed against gram-positive and gramnegative aerobes and anaerobes (e.g., vancomycin plus a
carbapenem), as well as high-dose aqueous penicillin G (16,000 to
20,000 U/d), the latter to treat clostridial pathogens, should be
administered. Approximately 50% of such infections are polymicrobial,
the remainder being caused by a single organism such as S.
pyogenes, P. aeruginosa, or C. perfringens. The microbiology of these
polymicrobial infections is similar to that of secondary microbial
peritonitis, with the exception that gram-positive cocci are more
commonly encountered. Most patients should be returned to the
operating room on a scheduled basis to determine if disease
progression has occurred. If so, additional resection of infected tissue
and débridement should take place. Antibiotic therapy can be refined
based on culture and sensitivity results, particularly in the case of
monomicrobial soft tissue infections. Adjunctive treatments, including
treatment with hyperbaric oxygen or IV Ig, have been described with
contradictory results. Hyperbaric oxygen therapy should be strongly
considered in patients with infection caused by gas-forming
organisms (e.g., C. perfringens). It may be reasonable to consider IV
Ig in patients with group A streptococcal infection with toxic shock
syndrome and in those patients with a high risk of death, such as the
elderly or those with hypotension or bacteremia.77
Postoperative Nosocomial Infections
 Surgical patients are prone to develop a wide variety of nosocomial infections
during the postoperative period, which include SSIs, UTIs, pneumonia, and
bacteremic episodes.78 SSIs are discussed above in Surgical Site Infections, and
the latter types of nosocomial infections are related to prolonged use of indwelling
tubes and catheters for the purpose of urinary drainage, ventilation, and venous
and arterial access, respectively.
 The presence of a postoperative UTI should be considered based on urinalysis
demonstrating WBCs or bacteria, a positive test for leukocyte esterase, or a
combination of these elements. The diagnosis is established after more than 10 4
CFU/mL of microbes are identified by culture techniques in symptomatic patients,
or more than 105 CFU/mL in asymptomatic individuals. Treatment for 3 to 5 days
with a single antibiotic that achieves high levels in the urine is appropriate.
Postoperative surgical patients should have indwelling urinary catheters removed
as quickly as possible, typically within 1 to 2 days, as long as they are mobile.
Cont…
 Prolonged mechanical ventilation is associated with an
increased incidence of pneumonia, and is frequently due to
pathogens common in the nosocomial environment.79
Frequently these organisms are highly resistant to many
different agents.80 The diagnosis of hospital-acquired
pneumonia should be made using the presence of a purulent
sputum, elevated leukocyte count, fever, and new chest x-ray
abnormality. The presence of two of the clinical findings, plus
chest x-ray findings, significantly increases the likelihood of
ventilator-associated pneumonia.81 Consideration should be
given to performing bronchoalveolar lavage to obtain
samples to assess by Gram's stain and obtaining a culture to
assess for the presence of microbes. Surgical patients
should be weaned from mechanical ventilation as soon as
feasible, based on oxygenation and inspiratory effort.
Cont…
 Infection associated with indwelling intravascular catheters
has become a common problem among hospitalized
patients. Because of the complexity of many surgical
procedures, these devices are increasingly used for
physiologic monitoring, vascular access, drug delivery, and
hyperalimentation. Among the several million catheters
inserted each year in the United States, approximately 25%
will become colonized, and approximately 5% will be
associated with bacteremia. Duration of catheterization,
insertion or manipulation under emergency or nonsterile
conditions, use for hyperalimentation, and perhaps the use of
multilumen catheters increase the risk of infection. Although
no randomized trials have been performed, peripherally
inserted central venous catheters have a similar catheterrelated infection rate.82
Cont…
 Many patients who develop intravascular catheter infections are
asymptomatic, often exhibiting an elevation in the blood WBC count. Blood
cultures obtained from a peripheral site and drawn through the catheter that
reveal the presence of the same organism increase the index of suspicion
for the presence of a catheter infection. Obvious purulence at the exit site of
the skin tunnel, severe sepsis syndrome due to any type of organism when
other potential causes have been excluded, or bacteremia due to gramnegative aerobes or fungi should lead to catheter removal. Selected catheter
infections due to low-virulence microbes such as S. epidermidis can be
effectively treated in approximately 50 to 60% of patients with a 14- to 21day course of an antibiotic, which should be considered when no other
vascular access site exists.83 The use of antibiotic-bonded catheters is
associated with lower rates of colonization.84 Routine, scheduled catheter
changes over a guidewire are associated with slightly lower rates of
infection, but an increase in the insertion-related complication rate.85 The
surgeon should carefully consider the need for any type of vascular access
device, rigorously attend to their maintenance to prevent infection, and
remove them as quickly as possible. Use of antibacterial or antifungal agents
to prevent catheter infection is of no utility and is contraindicated.
Sepsis
 Patients presenting with severe sepsis should
receive resuscitation fluids to a central venous
pressure target of 8 to 12 mmHg, with a goal of
mean arterial pressure of 65 mmHg or greater and
urine output of 0.5 mL/kg per hour or greater.
Delaying this resuscitative step for as little as 3
hours until arrival in the ICU has been shown to
result in poor outcome.88 Typically, this goal
necessitates early placement of central venous
catheter.
Cont…
 A number of studies have demonstrated the importance of
early empiric antibiotic therapy in patients who develop
sepsis or nosocomial infection. This therapy should be
initiated as soon as possible with broad-spectrum antibiotics
directed against most likely organisms, because early
appropriate antibiotic therapy has been associated with
significant reductions in mortality,89,90 and delays in
appropriate antibiotic administration are associated with
increased mortality.91 Use of institutional and unit specific
sensitivity patterns are critical in selecting an appropriate
agent for patients with nosocomial infection. It is key,
however, to obtain cultures of appropriate areas without
delaying initiating antibiotics so that appropriate adjustment
of antibiotic therapy can take place when culture results
return.
Cont…
 Multiple trials have evaluated the use of
vasopressors and inotropes for treatment of septic
shock. Current suggestions for first-line agents
based on effects on splanchnic perfusion include
norepinephrine, dopamine, and vasopressin.92,93 It
is important to titrate therapy based on other
parameters such as mixed venous oxygen
saturation and plasma lactate levels as well as
mean arterial pressure to reduce the risk of
vasopressor-induced perfusion deficits. Several
recent randomized trials have failed to
demonstrate benefit with use of pulmonary arterial
catheterization, leading to a significant decrease in
its use.
Cont…
 A number of other adjunctive therapies are useful in treatment of the
patient with severe sepsis and septic shock. Corticosteroids, first
evaluated unsuccessfully in the 1980s for treatment of sepsis (high
dose), have recently been reintroduced to the armamentarium of the
practitioner after the observation that many patients with septic
shock have a relative adrenal insufficiency. Low-dose
corticosteroids (hydrocortisone at 300 mg/d or less) can be used in
patients with septic shock who are not responsive to fluids and
vasopressors. However, a recent randomized trial failed to show
survival benefit. Recombinant human activated protein C
(drotrecogin alfa, Xigris) has been associated with significant
survival benefit in patients with severe sepsis and at least one organ
failure.94 In surgical patients, this therapy should be reserved for
patients with at least two organ failures or for patients with septic
shock. Patients with acute lung injury associated with sepsis should
receive mechanical ventilation with tidal volumes of 6 mL/kg and
pulmonary airway plateau pressures of 30 cm H2O or less. Finally,
red blood cell transfusion should be reserved for patients with
hemoglobin of less than 7 g/dL, with a more liberal transfusion
strategy reserved for those patients with severe coronary artery
disease, ongoing blood loss, or severe hypoxemia.
Blood-Borne Pathogens
 Although alarming to contemplate, the risk of HIV transmission from
patient to surgeon is low. By December 31, 2001, there had been
six cases of surgeons with HIV seroconversion from a possible
occupational exposure, from a total of 469,850 HIV cases to that
date reported to the Centers for Disease Control and Prevention. Of
the groups of health care workers with likely occupationally acquired
HIV infection (n = 195), surgeons were one of the lower risk groups
(compared to nurses at 59 cases and nonsurgeon physicians at 18
cases).95 Transmission of HIV (and other infections spread by blood
and body fluid) from patient to health care worker can be minimized
by observation of universal precautions, which include the following:
(a) routine use of barriers (such as gloves and/or goggles) when
anticipating contact with blood or body fluids, (b) washing of hands
and other skin surfaces immediately after contact with blood or body
fluids, and (c) careful handling and disposal of sharp instruments
during and after use. The current estimate of the risk of
transmission is 0.3% after needlestick.
Cont…
 Postexposure prophylaxis for HIV has significantly decreased
the risk of seroconversion for health care workers with
occupational exposure to HIV. Steps to initiate postexposure
prophylaxis should be initiated within hours rather than days
for the most effective preventive therapy. Postexposure
prophylaxis with a two- or three-drug regimen should be
initiated for health care workers with significant exposure to
patients with an HIV-positive status. If a patient's HIV status
is unknown, it may be advisable to begin postexposure
prophylaxis while testing is carried out, particularly if the
patient is at high risk for infection due to HIV (e.g., IV narcotic
use). Generally, postexposure prophylaxis is not warranted
for exposure to sources with unknown status, such as
deceased persons or needles from a sharps container.
Cont…
 The risks for surgeons of acquiring HIV infection have
recently been evaluated by Goldberg and coauthors.96 They
noted that the risks are related to the prevalence of HIV
infection in the population being cared for, the probability of
transmission from a percutaneous injury suffered while caring
for an infected patient, the number of such injuries sustained,
and the use of postexposure prophylaxis. Annual calculated
risks in Glasgow, Scotland, ranged from one in 200,000 for
general surgeons not utilizing postexposure prophylaxis to as
low as one in 10,000,000 with use of routine postexposure
prophylaxis after significant exposures.
Cont…
 Hepatitis C virus (HCV), previously known as non-A, non-B hepatitis, is a
RNA flavivirus first identified specifically in the late 1980s. This virus is
confined to humans and chimpanzees. A chronic carrier state develops in 75
to 80% of patients with the infection, with chronic liver disease occurring in
three fourths of patients developing chronic infection. The number of new
infections per year has declined since the 1980s due to the incorporation of
testing of the blood supply for this virus. Fortunately, HCV virus is not
transmitted efficiently through occupational exposures to blood, with the
seroconversion rate after accidental needlestick reported to be
approximately 2%.100 To date, a vaccine to prevent HCV infection has not
been developed. Experimental studies in chimpanzees with HCV Ig using a
model of needlestick injury have failed to demonstrate a protective effect of
this treatment in seroconversion after exposure, and no effective antiviral
agents for postexposure prophylaxis are available. Early treatment of
infection with INF- has been considered; however, this exposes patients who
may not develop HCV infection–related sequelae to the side effects of this
drug.101
Cont…
 Hepatitis B virus (HBV) is a DNA virus that affects only
humans. Primary infection with HBV generally is self-limited
(~6% of those infected are over 5 years of age), but can
progress to a chronic carrier state. Death from chronic liver
disease or hepatocellular cancer occurs in roughly 30% of
chronically infected persons. Surgeons and other health care
workers are at high risk for this blood-borne infection and
should receive the HBV vaccine; children are routinely
vaccinated in the United States.97 This vaccine has
contributed to a significant decline in the number of new
cases of HBV per year in the United States, from
approximately 27,000 new cases in 1984 to 4700 new cases
in 2006.98 In the postexposure setting, hepatitis B immune
globulin confers approximately 75% protection from HBV
infection.99
Thanks
for
your attention