Transmissible Diseases and Surgeons, rush Flashcards
(36 cards)
A patient with a known history of tuberculosis (TB) is
scheduled for bronchoscopy. Which of the following
statements is correct?
A. The endoscopy staff should wear a powered air-purifying
respirator (PAPR) during bronchoscopy.
B. The endoscopy staff should take prophylactic isoniazid
(INH) for 3 days after the procedure.
C. Bronchoscopy should be performed with the patient
under general anesthesia and the use of endotracheal
intubation.
D. Bronchoscopy should be deferred if the patient’s
tuberculin skin test result is positive.
E. Bronchoscopy is contraindicated until the result of the
purified protein derivative (PPD) test is available.
ANSWER: A
COMMENTS: Health care providers are at an increased risk for
exposure to TB during cough-inducing or aerosolizing procedures,
such as bronchoscopy, endotracheal intubation, or suctioning.
Respiratory protection requires the use of a particulate filter respirator or a PAPR. The latter device provides filtered air to a hood that
is worn. Use of a PAPR may be recommended when prolonged
exposure is possible, such as during bronchoscopy. The risk for
infection depends on the concentration of droplet nuclei and the
duration of exposure. The diagnosis of pulmonary TB is made
presumptively on the basis of the tuberculin skin test and chest
radiograph results and confirmed by acid-fast bacilli (AFB) smear
and culture results. Bronchoscopy is indicated for the diagnosis of
patients with undiagnosed pulmonary infection and for the exclusion of cancer, regardless of the skin test results.
Which of the following is not considered a standard precaution
for reducing the spread of transmissible diseases?
A. Hand washing before contact with a patient
B. Hand washing after glove removal
C. Wearing gloves during contact with a patient
D. Negative pressure airflow
E. Eye protection
ANSWER: D
COMMENTS: Standard, or universal, precautions are designed
to prevent the spread of transmissible disease by contact with blood,
body fluids, or any other potentially infected material. These precautions apply to all patients all the time. Hand washing is fundamental
and should be performed before and between each contact with a
patient and after glove removal. Gloves are worn when contacting a
potentially contaminated area. Surgical masks and eye protection are
required if mucous membrane or eye exposure is possible. Gowns
are a part of standard precautions when more extensive blood or fluid
exposure may occur. Specific engineering controls for airflow and
processing of air are integral to preventing the spread of certain
airborne pathogens and as such are not a component of basic standard
precautions. Specific procedures for infection control are mandated
by federal regulatory agencies. Surgeons and all health care workers
(HCWs) must be familiar with the specific infection control policies
and procedures established at their places of work
A 60-year-old woman with a history of multiple soft tissue
abscesses has a recurrent abscess on her right thigh. This
patient had a recent hospitalization for exacerbation of
congestive heart failure, during which she was in the hospital
for 5 days. Because of her history of previous methicillinresistant Staphylococcus aureus (MRSA) abscesses, vancomycin therapy is started. On morning rounds, all of the
following precautions should be taken except:
A. Washing hands before examining the patient
B. Wearing gloves while examining the patient
C. Wearing a mask while examining the patient
D. Wearing a gown while examining the patient
E. Washing hands after examining the patient
NSWER: C
COMMENTS: Contact precautions are indicated in this patient
and include washing one’s hands both before and after leaving the
patient’s room and donning both a gown and gloves while in the
patient’s room. Wearing a mask is not indicated for patients who
are on contact precautions.
A 68-year-old woman is admitted to the hospital for
neurosurgery after being found comatose at home. The
patient lives alone, but her neighbor states that she has been
“acting strangely” for the last several weeks. No additional
history is available. Magnetic resonance imaging of the brain
reveals evidence of focal cerebritis and enlarged ventricles
along with enhancement of the basilar meninges. A chest
radiograph shows upper lobe consolidation. Results of a
rapid human immunodeficiency virus (HIV) test are positive.
The patient is taken to the operating room for placement of a
ventricular drain. Which type of isolation would be needed
for this patient in the postoperative period?
A. Standard and airborne precautions
B. Airborne precautions
C. Droplet precautions
D. Contact precautions
E. Reverse isolation
ANSWER: A
COMMENTS: This HIV-infected patient has evidence of meningitis, cerebritis, and upper lobe pneumonia. The unifying diagnosis 74 SECTION I / Surgical Fundamentals
is pulmonary and cerebral TB. This patient requires airborne
precautions.
A variety of infection control measures are implemented to
decrease the risk for transmission of microorganisms in hospitals.
Standard precautions are used for the care of all patients. Hand
washing between patient contact and the use of barrier protection,
such as gloves, gowns, and masks, to minimize exposure to potentially infectious body fluids (e.g., blood, feces, and wound drainage) are important components of standard precautions and all
infection control programs.
In addition to standard precautions, airborne precautions are
used for patients with known or suspected illness transmitted via
small airborne droplets (≤5 μm). TB, measles, smallpox, and varicella (chickenpox) are examples of diseases requiring airborne
precautions. Because these organisms can be dispersed widely by
air currents and may remain suspended in the air for long periods,
special air handling and ventilation are necessary. Patients requiring airborne precautions are placed in “negative pressure” rooms,
and all persons entering the room require an N95 mask.
In addition to standard precautions, droplet precautions are
used for patients with suspected or proven invasive disease caused
by Haemophilus influenzae or Neisseria meningitidis (e.g., pneumonia, meningitis, or sepsis) or other respiratory illnesses such as
diphtheria, pertussis, pneumonic plague, influenza, mumps, and
rubella. The droplets produced by these illnesses are usually generated by coughing but are larger than the droplets described earlier
(>5 μm), travel only short distances (<3 ft), and do not remain
suspended in air. Patients require a private room, and persons entering the room require a surgical mask.
In addition to standard precautions, contact precautions apply
to specific patients infected or colonized with epidemiologically
important organisms that spread by direct contact with a patient or
contact with items in the patient’s environment. These organisms
may demonstrate antibiotic resistance and include MRSA, vancomycin-resistant S. aureus, vancomycin-resistant enterococci (VRE),
and multidrug-resistant gram-negative bacilli. Enteric pathogens
such as Clostridium difficile and skin infections such as impetigo
(group A streptococci), herpes simplex, and scabies also require
contact precautions
Which of the following statements regarding MRSA is true?
A. The treatment of choice is clindamycin.
B. MRSA can only be found in the health care setting.
C. MRSA is more virulent than methicillin-sensitive S.
aureus.
D. Treatment of surgical patients with intranasal mupirocin
decreases wound infection rates with MRSA.
E. Hospitalized patients colonized with MRSA require
contact isolation.
ANSWER: E
COMMENTS: Staphylococci are the most common cause of nosocomial infections in surgical patients. Recent reports suggest that
carriage of MRSA in the community has increased, and more infections with this organism are being seen in persons without health
care–associated risks.
At the beginning of the antibiotic era, S. aureus was susceptible to penicillins. Resistance developed to penicillin via
β-lactamase production, and new antibiotics were discovered,
including the penicillinase-resistant penicillins (methicillin, oxacillin, nafcillin, etc.). MRSA is by definition resistant to methicillin.
Methicillin is not used in clinical practice because it induces interstitial nephritis, but it is still used in the laboratory to differentiate
methicillin-susceptible S. aureus (MSSA) from MRSA. Vancomycin or linezolid can be used to treat MRSA. S. aureus strains with
intermediate susceptibility to vancomycin and vancomycin-resistant S. aureus have been reported in the United States.
Although some studies suggest that mortality after MRSA infection is higher than that after MSSA infection, the increased death rate
is most likely due to comorbid conditions and not due to differences
in virulence between MSSA and MRSA. Hospitalized patients colonized with MRSA require contact isolation to avoid the spread of the
bacteria to other patients. A recent prospective, randomized, placebocontrolled study showed that intranasal mupirocin did not significantly reduce S. aureus surgical site infections.
Which of the following statements regarding hand hygiene is
true?
A. The use of soap and water for hand washing is required
before and after each contact with a patient.
B. HCWs should clean their hands with an antiseptic-containing agent before and after each contact with a patient.
C. Adherence to hand hygiene guidelines by HCWs is high.
D. Application of alcohol-based products to the palmer surface
of the hands and fingers is adequate for hand washing.
E. VRE and MRSA are rarely seen on the hands of HCWs
ANSWER: B
COMMENTS: Hand washing by HCWs may be the single most
effective measure for preventing nosocomial infection. The spread
of bacteria, particularly antibiotic-resistant organisms such as MRSA
and VRE, from contaminated HCWs to patients is well documented.
Despite recommendations to wash hands before and after all contact
with patients, adherence to such policies by HCWs has been poor.
Although hand washing with soap and water is required when hands
are visibly soiled with blood, alcohol-based products may be used
instead of soap and water as long as the hands are not visibly soiled.
Alcohol-based products are superior to antimicrobial soaps for standard hand decontamination. Alcohol-based hand rubs have the
broadest spectrum of antimicrobial activity among the available hand
hygiene products, and their use results in a rapid reduction in microbial skin counts. The ability to make these rubs available at the
entrance to patients’ rooms, at the bedside, or in pocket-sized containers to be carried by HCWs may improve compliance with hand
hygiene policies. Alcohol-based hand rubs must be applied to all
surfaces of the hands and fingers, and the hands and fingers should
be rubbed together until they are dry. The Centers for Disease Control
(CDC) has recently published guidelines for hand hygiene in health
care settings that include recommendations for hand-washing antisepsis, hand hygiene techniques, and surgical hand antisepsis.
A surgical resident performs endotracheal intubation of a
patient. The patient is unknown to the resident, and the
resident had not worn a mask during intubation. Subsequently, the resident is informed that the patient has active
TB. The resident has had previous negative PPD tests. The
appropriate measure for the resident is:
A. No intervention is necessary.
B. The resident should have a PPD test performed, and
prophylactic INH started regardless of the result.CHAPTER 5 / Surgical Infection and Transmissible Diseases and Surgeons 75
C. The resident should have a PPD test performed, and
prophylactic INH started only if the result is positive and
the resident does not have symptoms of active infection.
D. The resident should have a PPD test performed, and INH
started only if the result is positive and symptoms
develop in the resident.
E. The resident does not need a PPD test but should have
chest radiography performed.
ANSWER: C
COMMENTS: Exposure to Mycobacterium tuberculosis is determined by skin testing. If there is any concern for exposure to an
active disease, especially in a high-risk situation such as intubation
in which the resident is directly exposed to respiratory secretions, the
patient should have a PPD test performed. If the PPD results are
positive, the resident should begin treatment with INH. A chest radiograph should not be performed in place of the PPD test. If symptoms
develop, a chest radiograph is warranted. Infection develops in less
than 10% of exposed individuals. Skin testing is performed at least
annually in HCWs. The majority of PPD-positive individuals have
old exposures. However, when the PPD test results are positive, a
chest radiograph and sputum for AFB smear and culture are obtained.
INH prophylaxis is indicated for persons younger than 35 years with
positive skin test results and those older than 35 years with high-risk
conditions (i.e., HIV infection, injected drug use, contact with a
known TB source, from a medically underserved population, foreign
born, or those with abnormal chest radiograph results). The duration
of prophylaxis is 6 to 12 months. Active pulmonary TB is diagnosed
by sputum AFB smear or culture analysis (or both). The standard
treatment of active disease involves a multidrug regimen with INH,
rifampin (RIF), and other drugs (pyrazinamide, ethambutol, or streptomycin) for months. Surgical therapy (usually resection) is occasionally necessary for patients who fail medical therapy or for those
in whom persistent problems develop, such as a residual lung cavity
or destruction, bronchiectasis, or hemoptysis.
A 60-year-old immigrant from China is admitted to the
hospital with fevers and a cough productive of bloody
sputum. A chest radiograph demonstrates a right upper lobe
infiltrate. The patient’s TB exposure is unknown. Which of
the following precautions is appropriate?
A. No precautions are necessary.
B. The patient should be admitted to a shared room but be
required to wear a mask.
C. The patient should be admitted to a private room but does
not need a mask during transport.
D. The patient should be admitted to a private room and
should wear a mask during transport.
E. The patient should be admitted to a negative pressure
private room and wear a mask during transport.
ANSWER: E
COMMENTS: Airborne precautions are necessary to reduce the
exposure of staff and other patients to individuals with suspected
pulmonary or laryngeal TB. Early recognition of patients at risk for
TB is critical, including patients with possible symptoms of TB and
those at a higher risk for active disease. Typical symptoms include
persistent cough, bloody sputum, fever, night sweats, and weight loss.
A chest radiograph may show a cavitary lesion or upper lobe infiltrate.
Individuals at a higher risk include the homeless, elderly, known contacts of TB cases, injected drug users, foreign-born individuals, and
patients with HIV infection, renal failure, malignancy, or immunosuppression. The largest growing proportion of new TB cases is in the
HIV-infected and immunosuppressed population. Persons with suspected TB must have their face covered with a surgical mask during
transport and should be admitted to a private negative airflow room
equipped with engineering controls specifically designed to reduce
airborne exposure. Precautions must be implemented promptly for any
suspected case and should not be delayed to wait for confirmation by
AFB culture results, which may take weeks. Staff entering the patient’s
roommustwearspecial particulate filterrespirators(fit testing required)
or equivalent respirator systems. Use of appropriate respiratory equipment for the protection of HCWs is mandated by the Occupational
Safety and Health Administration (OSHA) and the National Institute
of Occupational Safety and Health (NIOSH).
The operating surgeon is stuck with a needle while performing elective repair of an inguinal hernia. The patient is
known to be HIV negative, but his hepatitis C virus (HCV)
status is unknown. The patient has a known history of
intravenous drug abuse. In addition, the operating surgeon is
hepatitis B immune because of previous vaccination. Which
one of the following measures is appropriate?
A. Prophylactic antiviral treatment
B. Administration of HCV vaccine and immunoglobulin if
the surgeon is HCV antibody negative
C. Baseline testing of the surgeon and patient for HCV and
follow-up testing of the surgeon at 4 to 6 months
D. No testing for the surgeon is indicated if the patient tests
negative for HCV
E. Prophylactic administration of HCV immunoglobulin in
addition to baseline testing of both the surgeon and
patient and follow-up testing of the surgeon in 4 to 6
months
ANSWER: C
COMMENTS: Anytime that someone is inadvertently stuck with
a needle from a patient with unknown HCV status, both the patient
and the person stuck should undergo baseline testing for HCV. In
addition, the person stuck should have follow-up testing at 4 to 6
months. There is no treatment that has proven efficacy in reducing
the risk for seroconversion with HCV; therefore no prophylaxis for
HCV infection is currently indicated.
A surgical resident is placing a central venous catheter in a
patient who is HIV positive and is stuck with the needle.
Which of the following regarding postexposure prophylaxis
is true?
A. No prophylaxis is necessary; however, the surgical
resident should have a baseline HIV test performed and
follow-up tests in 3 and 6 months.
B. The resident should have a baseline HIV test performed
and follow-up testing in 3 and 6 months and, in addition,
begin combined triple antiretroviral therapy.
C. The resident should have a baseline HIV test performed
and follow-up testing in 3 and 6 months and, in addition,
begin single antiretroviral therapy.76 SECTION I / Surgical Fundamentals
D. The resident should have a baseline HIV test performed
and follow-up testing in 3 and 6 months and, in addition,
begin therapy with two antiretroviral drugs.
E. The resident should begin combined triple antiretroviral
therapy and have an HIV test performed in 6 months.
ANSWER: B
COMMENTS: Most occupationally acquired HIV infection has
been documented in nurses or laboratory technicians. Postexposure
drug prophylaxis should be initiated as soon as possible, ideally
within 2 h. In cases where the status of the source is unknown,
standard serologic testing (enzyme immunoassay and Western
blot) is indicated, but the results may take several days. A rapid
HIV test can now give results within 1 h. However, serologic test
results may be negative in infected individuals for 3 to 12 weeks
following the acquisition of the virus. The decision to start postexposure drug prophylaxis must therefore consider any known risk
factors that the source may have, regardless of the serologic results.
Postexposure prophylaxis consists of multidrug therapy with a
combination of nucleoside and protease inhibitors. Adverse side
effects are frequent and sometimes severe. Recommendations for
postexposure prophylaxis continue to evolve. The most effective
method of reducing the risk for transmission of HIV to a person
stuck with a needle from a known HIV-positive patient is to begin
combined triple antiretroviral therapy. The first dose should be
given after exposure as soon as possible. Besides a baseline HIV
test, this person should undergo an additional follow-up testing at
both 3 and 6 months
A nonimmune surgical resident is stuck by a contaminated
needle from a hepatitis B surface antigen (HBsAg)-positive
source. Which of the following is the correct initial treatment?
A. None because the patient does not have active hepatitis B
virus (HBV) infection and is immune to HBV
B. Interferon
C. Vaccination against HBV
D. Hepatitis B immune globulin (HBIG)
E. Vaccination against HBV and administration of HBIG
ANSWER: E
COMMENTS: The best method of preventing occupational HBV
infection is to vaccinate all HCWs at risk if they do not have natural
immunity from previous infection. When exposure occurs, the
affected area should be immediately and thoroughly washed with
soap and water. The source is tested for HBV, HCV, and HIV. If the
source tests positive for HBV, nonimmune individuals are given
HBIG for passive prophylaxis and are vaccinated. If a previously
vaccinated individual incurs a needle injury, titers should be checked
and a dose of vaccine given if titers are not detected. Interferon is
not used for prophylaxis following acute exposure but may be useful
for some patients with chronic HBV or HCV infection.
Which of the following is an important risk factor for transmission of HIV to the surgeon after a percutaneous injury?
A. The source patient has advanced HIV infection with a
CD4+ T-cell count less than 50 cells/mm3.
B. The surgeon sustains a deep puncture injury.
C. Blood was visible on the sharp object causing the
injury.
D. The injury was caused by a device that had entered a
blood vessel of the source patient before injury.
E. All of the above.
ANSWER: E
COMMENTS: See Question 13.
13. What is the approximate probability of transmission of HCV
to an HCW through a needlestick injury from an infected
source?
A. 0.3%
B. 3%
C. 15%
D. 30%
E. 50%
ANSWER: B
COMMENTS: The risk for transmission of HIV after percutaneous exposure to HIV-infected blood is about 0.3%. This risk is
influenced by several factors, including depth of the injury and the
presence of undiluted blood on the device causing the injury. Exposure to blood from patients in the terminal stages of acquired
immune deficiency syndrome (AIDS), which probably reflects high
titers of circulating virus, also increases the risk to HCWs. Although
no prospective study demonstrating benefit from postexposure prophylaxis with antiretroviral agents has been completed, a retrospective case-control study suggests that in those who receive zidovudine
prophylaxis after exposure, the odds of HIV infection were reduced
significantly (by approximately 80%). Postexposure prophylaxis,
which now includes at least two antiretroviral agents, should be
started immediately (within 72 h) in HCWs with high-risk
injuries.
HCWs are at risk for contracting transmissible viral disease
when stuck by needles with contaminated blood or by exposure of
mucosal membranes to blood or other body fluids. The risk for
documented seroconversion is approximately 3%–10% for HCV.
The risk for HBV infection after needlestick injury is 5%–30%.
The risk for HCV infection following mucous membrane or other
cutaneous exposure has not been defined. The risk for HIV infection with mucous membrane exposure is about 0.1%. When exposure occurs, the infected area should be washed thoroughly with
soap and water. The source should be tested for infection with HBV,
HCV, and HIV. The risk of contracting HIV infection is greatest
with hollow needles, with deep intramuscular injury, or when the
exposure involves a greater amount of virus (i.e., from a larger
amount of blood or a source with late-stage HIV infection).
A surgical resident is stuck with an HCV-contaminated
hollow-bore needle. Which of the following tests should be
done initially?
A. Detection of HCV RNA
B. Detection of HCV surface antigen
C. Detection of HCV antibodies by enzyme immunoassay
D. Measurement of viral load
E. Detection of HCV core antigen
ANSWER: C
COMMENTS: The initial screening test for HCV is an antibody
immunoassay. The person stuck with the contaminated needle should
have baseline testing performed. Since it can take up to 6 months
for a person to seroconvert, called the window period, people who
have been stuck with a contaminated needle not only require baseline
testing but will also need follow-up testing in 6 months.
Which of the following blood tests confirms HCV infection?
A. Detection of HCV RNA
B. Detection of HCV surface antigen
C. Detection of HCV antibodies by enzyme immunoassay
D. Detection of HCV antibodies and alanine aminotransferase levels of 500 to 1000 u/L
E. Measurement of HCV viral load
ANSWER: A
COMMENTS: The screening test for HCV is an immunoassay
for anti-HCV antibodies. Although the results are positive in 90% of
patients infected with HCV, the predictive value of the test is limited
when the prevalence of infection is low. In addition, anti-HCV antibodies may not be detectable for up to 18 weeks following exposure.
Their presence does not differentiate the state of infection. Qualitative reverse transcriptase polymerase chain reaction (RT–PCR) for
detection of HCV RNA is confirmatory. Infection may also be confirmed by recombinant immunoblot assay for HCV antibody.
A 36-year-old man with HIV infection and a CD4+ count
less than 500 cells/mm3 has an incarcerated ventral hernia. In
addition to standard precautions, which one of the following
is recommended?
A. Avoidance of prosthetic mesh
B. Broader preoperative prophylactic antibiotic coverage
than for a patient who is HIV negative
C. Prophylactic trimethoprim/sulfamethoxazole in addition
to standard preoperative antibiotics
D. Disposable surgical instruments
E. None of the above
ANSWER: E
COMMENTS: Beyond the universal precautions that are used for
all patients, there are no specific recommendations regarding the
preoperative or intraoperative management of patients with HIV
infection. Operative treatment should be performed according to the
surgical condition and antiretroviral drug therapy administered
according to the status of the HIV disease. Prophylactic antibiotics or
prosthetic materials are used for the same indications in HIV-infected
individuals as in non–HIV-infected individuals. Trimethoprim/sulfamethoxazole is used for the prophylaxis of Pneumocystis carinii
pneumonia in patients with clinical AIDS but has nothing to do with
surgical prophylaxis. Standard surgical instruments and sterilization
techniques are appropriate. The use of disposable instruments is often
convenient and simple when performing minor procedures outside
the main operating room.
What is the prevalence of HCV infection in the United States? A. 0.2% B. 2% C. 5% D. 10% E. 20%
ANSWER: B
COMMENTS: The prevalence of HCV in the United States is
approximately four times greater than that of HIV infection. The
rate in HCWs, including general, orthopedic, and oral surgeons, is
no higher. As would be expected, some populations have a much
higher prevalence, including hemophiliacs (60%–90%), injectable
drug users (60%–90%), and chronic hemodialysis patients (up to
60%).
During an emergency appendectomy, a surgical resident
sustains an injury from a contaminated hollow-bore
needle with spontaneous bleeding. Which one of the
following blood-borne organisms is most likely to be
transmitted, assuming that the patient was infected with
all of them?
A. HIV
B. HBV
C. HCV
D. Plasmodium spp. (malaria)
E. Treponema pallidum (syphilis)
ANSWER: B
COMMENTS: All the organisms mentioned in the list are potentially transmissible through the exposure described. After significant exposure to blood-borne pathogens, the risk is about 30% for
acquiring hepatitis B, 3% for hepatitis C, and 0.3% for HIV disease.
Malaria and syphilis may be acquired through blood transfusion,
and acquisition through a needlestick is theoretically possible.
Because of the high risk associated with hepatitis B exposure, it is
recommended that all HCWs be vaccinated against HBV. In the
event that a nonimmune HCW is exposed to HBV, it is recommended that the HCW receive HBIG within 7 days of the exposure
and also start a vaccination series. Postexposure prophylaxis with
antiretroviral drugs may be indicated after exposure to HIV-infected
blood. There is no postexposure prophylaxis available against
HCV
A surgical resident sustains a needlestick injury with a
hollow-bore needle contaminated with the blood of a
patient who is hepatitis B antigen positive. The resident
completed a series of three hepatitis B vaccines 1 year ago,
but his antibody response was not checked. Which of the
following statements best describes the management of this
case?
A. Observation only is indicated since the source does not
have active HBV infection.
B. The resident needs a booster of hepatitis B vaccine.
C. The resident should receive HBIG immediately.78 SECTION I / Surgical Fundamentals
D. The resident should receive HBIG and a hepatitis B
vaccine booster immediately.
E. The resident needs to be tested for anti–hepatitis B
antibody immediately. If the test result is negative,
proceed as in option D.
ANSWER: E
COMMENTS: HCWs who sustain injuries from needles contaminated with blood containing HBV have a risk for the development
of serologic evidence of HBV infection as high as 62%. The source
patient is hepatitis B antigen positive, which is an indication of
active HBV infection. The resident has been vaccinated against
HBV, but his immune status is unknown and should be determined.
If the resident is anti–hepatitis B antibody positive, no intervention
is necessary. However, if the resident is anti–hepatitis B antibody
negative, HBIG (which can be given up to 7 days after the exposure) and a hepatitis B vaccine booster should be administered. If
the resident was never vaccinated, HBIG should be administered
immediately and the hepatitis B vaccination series begun.
Which of the following precautions regarding care for
patients with C. difficile is true?
A. Only gloves are required when examining the patient.
B. Stethoscopes do not need to be cleaned after use.
C. The patient should be placed in a private room.
D. All visitors should wear gloves, a gown, and a mask.
E. Alcohol-based hand sanitizers are adequate to clean
hands after exiting a patient’s room.
ANSWER: C
COMMENTS: C. difficile is spread by direct contact, and thus
contact precautions must be followed. Appropriate precautions
include donning a gown and gloves and washing hands both before
entering and after leaving the patient’s room. Alcohol-based hand
sanitizers do not kill C. difficile, and thus hand washing with soap
and water, particularly after leaving a patient’s room, is required.
There is no indication for anyone to wear a mask in this patient’s
room. In addition, the patient should be placed in a private room.
It is also ideal to have a disposable stethoscope dedicated to that
patient to avoid spreading C. difficile. If not available, the stethoscope must be cleaned thoroughly after use.
. Which of the following clinical conditions is identified by the
presence of antibodies in the serum against HBsAg (antiHBs) in the absence of hepatitis B core antigen (anti-HBc)
and HBsAg?
A. The patient is susceptible to HBV infection.
B. The patient is immune because of HBV vaccination.
C. The patient has an active acute infection with HBV.
D. The patient has chronic active hepatitis with HBV.
E. The patient has recovered from an HBV infection with
subsequent natural immunity
ANSWER: B
COMMENTS: Testing for HBsAg will be positive in both patients
who have been immunized against HBV and those who were
previously infected. To distinguish the two clinical situations, one
must use other tests. HBsAg positivity indicates an active infection,
either acute or chronic. Anti-HBc–positive results indicate that a
person either currently has an active infection or has been infected
with HBV in the past. If both are negative in the setting of positive
anti-HBs, the person has been vaccinated but never infected with
HBV
Which of the following markers is the most clinically useful
for monitoring the course of a person infected with HIV?
A. Viral load
B. CD4+ T-cell count
C. Serum neopterin
D. Serum oligoclonal immunoglobulins
E. Serum p24 antigen level
ANSWER: B
COMMENTS: The CD4+ T-cell count, although somewhat
imperfect, is the most useful determination for monitoring the
course of an HIV infection. The normal CD4+ count is greater than
600 cells/mm3, with most counts ranging from 800 to 1200 cells/
mm3. Symptomatic disease usually begins when the CD4+ count
falls below 300 to 400 cells/mm3. Opportunistic infections begin
to occur when the CD4+ cell count is less than 200 cells/mm3. The
time course of this decline in CD4+ T-cell count is prolonged and
may take more than 10 years. Direct quantification of viral load
with plasma viremia shows increasing viral titers as the disease
progresses. β2-Microglobulin is shed into the serum in HIVinfected patients and reflects increased lymphocyte turnover.
Neopterin is produced by macrophages stimulated by interferon.
Although both are found in increasing amounts as HIV infection
progresses, neither of these two determinations is specific for HIV
infection, and they are generally used in a research setting. Determination of p24 antigen is specific for HIV but not very
sensitive.`
The chance of an HIV-infected individual transmitting
infection best correlates with which of the following?
A. CD4+ T-cell count
B. Viral load
C. Absolute lymphocyte count less than 1000 cells/mm3
D. Active opportunistic infection
E. Whether the patient is currently receiving antiretroviral
therapy
ANSWER: B
COMMENTS: Blood measurements of viral load reflect the risk
for transmission of HIV by any route: parenteral, sexual, or perinatal. The risk of acquiring HIV infection through occupational
exposure also correlates with the viral load in the source. Both viral
load and the CD4+ count reflect the stage of the disease as patients
with late viral infection have low CD4+ levels and high viral
counts. Opportunistic infections are also more prevalent as CD4+
counts fall and immunodeficiency worsens. Clinical AIDS is
defined in patients with positive HIV serologic findings when
CD4+ counts are less than 200 cells/mm3 or when one of a number
of defined associated conditions exists. The list of theseCHAPTER 5 / Surgical Infection and Transmissible Diseases and Surgeons 79
AIDS-defining conditions includes specific opportunistic infections, neoplasms, and degenerative conditions.
A 28-year-old woman with AIDS has right upper quadrant pain
and is found to have acute cholecystitis on ultrasound examination. Which of the following is the appropriate therapy?
A. The patient should begin antibiotic therapy but should
undergo no surgical intervention because of her immune
status.
B. The patient should begin antibiotic therapy and have a
percutaneous cholecystostomy tube placed.
C. The patient should begin antibiotic therapy and undergo
open cholecystectomy.
D. The patient should begin antibiotic therapy and undergo
laparoscopic cholecystectomy.
E. None of the above.
ANSWER: D
COMMENTS: AIDS and HIV infection are not contraindications
to laparoscopy. These patients should be managed according to
routine general surgery principles. A patient with AIDS and acute
cholecystitis should be treated with appropriate antibiotics and
laparoscopic cholecystectomy unless the patient is not stable
enough or has other comorbid conditions that make surgery too
dangerous.
The operative mortality rate after laparotomy in patients with
AIDS has most closely been associated with which of the
following?
A. Total lymphocyte count less than 1000 cells/mm3
B. CD4+ T-cell count less than 500/mm3
C. Active opportunistic infection
D. Duration of HIV infection
E. Emergency surgery
ANSWER: E
COMMENTS: Prognostic factors in AIDS patients undergoing
abdominal operations have not been extensively analyzed. The
cumulative operative mortality rate after major abdominal procedures is approximately 20%. Most deaths are related to the patient’s
underlying disease and not to specific operative complications.
Emergency operations have been associated with higher mortality
rates than elective procedures, particularly in patients with intestinal
perforations because of opportunistic infections such as cytomegalovirus (CMV). However, there is no convincing evidence that patients
with HIV infection withoutAIDS-defining criteria have an inordinate
risk for death or complications after abdominal surgery.
