IV-239. While attending the University of Georgia, a group of friends go on a 5-day canoeing and camping trip in rural southern Georgia. A few weeks later, one of the campers develops a serpiginous, raised, pruritic, erythematous eruption on the buttocks. Strongyloides larvae are found in his stool. Three of his companions, who are asymptomatic, are also found to have Strongyloides larvae in their stool. Which of the following is indicated in the asymptomatic carriers?
E. Treatment only for symptomatic illness
IV-240. All of the following are clinical manifestations of Ascaris lumbricoides infection EXCEPT:
A. Asymptomatic carriage
B. Fever, headache, photophobia, nuchal rigidity, and eosinophilia
C. Nonproductive cough and pleurisy with eosinophilia
D. Right upper quadrant pain and fever
E. Small bowel obstruction
IV-241. A 21-year-old college student in Mississippi comes to student health to ask advice about treatment for ascaris infection. He is an education major and works 1 day a week in an elementary school, where a number of the students were recently diagnosed with ascariasis over the past 3 months. He feels well and reports being asymptomatic. A stool O&P reveals characteristic ascaris eggs. Which of the following should you recommend?
B. Diethylcarbamazine (DEC)
IV-242. A 38-year-old woman presents to the emergency department with severe abdominal pain. She has no past medical or surgical history. She recalls no recent history of abdominal discomfort, diarrhea, melena, bright red blood per rectum, nausea, or vomiting before this acute episode. She ate ceviche (lime-marinated raw fish) at a Peruvian restaurant 3 hours before presentation. On examination, she is in terrible distress and has dry heaves. Her temperature is 37.6░C, heart rate is 128 beats/min, and blood pressure is 174/92 mmHg. Examination is notable for an extremely tender abdomen with guarding and rebound tenderness. Bowel sounds are present and hyperactive. Rectal examination
findings are normal, and Guaiac test result is negative. The pelvic examination is unremarkable. The white blood cell count is 6738/μL and hematocrit is 42%. A complete metabolic panel and lipase and amylase levels are all within normal limits. CT of the abdomen shows no abnormality. What is the next step in her management?
A. CT angiogram of the abdomen
B. Pelvic ultrasonography
C. Proton pump inhibitor therapy and observation
D. Right upper quadrant ultrasonography
E. Upper endoscopy
IV-243. While participating in a medical missionary visit to Indonesia, you are asked to see a 22-year-old man with new onset of high fever, groin pain, and a swollen scrotum. His symptoms have been present for about 1 week and worsening steadily. His temperature is 38.8░C, and his examination is notable for tender inguinal lymphadenopathy, scrotal swelling with a hydrocele, and lymphatic streaking. All of the following may be useful in diagnosing his condition EXCEPT:
A. Examination of blood
B. Examination of hydrocele fluid
C. Scrotal ultrasonography
D. Serum ELISA
E. Stool O&P
IV-244. The patient described above should be treated with which of the following medications?
B. Diethylcarbamazine (DEC)
IV-245. A 45-year-old woman is brought to the Emergency department by her daughter because she saw something moving in her motherĺs eye. The patient is visiting from Zaire, where she lives in the rain forest. The patient reports some occasional eye swelling and redness. On examination, you find a worm in the subconjunctiva (Figure IV-245). Which of the following medications is indicated for therapy?
FIGURE IV-245 (see Color Atlas)
B. Diethylcarbazine (DEC)
IV-246. All of the following statements regarding the epidemiology of schistosomal infection are true EXCEPT:
A. S. haematobium infection is seen mostly in South America.
B. S. japonicum infection is seen mostly in China, Philippines, and Indonesia.
C. S. mansoni infection is seen in Africa, South America, and the Middle East.
D. Schistosomal infection causes acute and chronic manifestations.
E. Transmission of all human schistosomal infections is from snails.
IV-247. A 48-year-old female presents to her physician with a 2-day history of fever, arthralgias, diarrhea, and headache. She recently returned from an ecotour in tropical sub-Saharan Africa, where she went swimming in inland rivers. Notable findings on physical examination include a temperature of 38.7░C (101.7░F); 2-cm tender mobile lymph nodes in the axilla, cervical, and femoral regions; and a palpable spleen. Her white blood cell count is 15,000/μL with 50% eosinophils. She should receive treatments with which of the following medications?
IV-248. A person with liver disease caused by Schistosoma mansoni would be most likely to have what condition?
B. Esophageal varices
E. Spider nevi
IV-249. A 26-year-old man is brought to the emergency department after the onset of a grand mal seizure. On arrival to the hospital, the seizure had terminated, and he was somnolent without focal findings. Vital signs were normal except for tachycardia. The patient has no known medical history and no history of illicit drug or alcohol use. He takes no medications. At a routine clinic visit 3 months earlier, he was documented to be HIV antibody and PPD negative. He is originally from rural Guatemala and has been in the United States working as a laborer for the past 3 years. A contrast CT shows multiple parenchymal lesions in both hemispheres that are identical to the one shown in the posterior right brain (Figure IV-249). After acute stabilization, including anticonvulsant therapy, which of the following is the most appropriate next step in this patientĺs management?
A. Echocardiogram with Doppler examination of aortic and mitral valves
B. Initiation of praziquantel therapy
C. Initiation of pyrimethamine and sulfadiazine therapy
D. Measurement of HIV viral load
E. Neurosurgical consultation for brain biopsy
IV-250. A 44-year-old woman presents to the emergency department with recurrent episodes of right upper quadrant pain, typically soon after meals. These episodes have been present for at least 1 month and seem to be worsening. The patient emigrated from Lebanon more than 20 years ago and works as an attorney. She takes no medications and is physically active. On examination, she is jaundiced and in obvious discomfort because of right upper quadrant pain. She is afebrile and tachycardic. Her physical examination is notable for an enlarged liver. Ultrasound examination confirms the large liver and
demonstrates a complex 14-cm cyst with daughter cysts extending to the liver edge with associated biliary tract dilation. Which of the following is the most appropriate management approach to this patient?
A. Albendazole medical therapy
B. Albendazole followed by surgical resection
C. Needle biopsy of the cystic lesion
D. PAIR (percutaneous aspiration, infusion of scolicidal agent, and reaspiration)
E. Serologic testing for E. granulosus
IV-1. The answer is B. (Chap. 119) Deficiencies in the complement system predispose patients to a variety of infections. Most of these deficits are congenital. Patients with sickle cell disease have acquired functional defects in the alternative complement pathway. They are at risk of infection from Streptococcus pneumoniae and Salmonella spp. Patients with liver disease, nephrotic syndrome, and systemic lupus erythematosus may have defects in C3. They are at particular risk for infections with Staphylococcus aureus, S. pneumoniae, Pseudomonas spp., and Proteus spp. Patients with congenital or acquired (usually systemic lupus erythematosus) deficiencies in the terminal complement cascade (C5-8) are at particular risk of infection from Neisseria spp. such as N. meningitis or N. gonorrhoeae.
IV-2. The answer is A. (Chap. 121) Choosing the appropriate empiric coverage for patients with severe sepsis is important for improving outcomes. This patient has undergone splenectomy in the distant past and is at 58 times greater risk for overwhelming bacterial sepsis than the normal population. The risk is greatest in the first 2 years after splenectomy but persists across the entire lifetime. The most common organisms causing severe sepsis in asplenic patients are encapsulated bacteria, especially Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. S. pneumoniae causes 50% to 70% of severe sepsis in asplenic patients. The recommended empiric antibiotics in asplenic patients with sepsis are ceftriaxone 2 g IV every 12 hours and vancomycin 1 g IV every 12 hours.
IV-3. The answer is C. (Chap. 121) Necrotizing fasciitis is a life-threatening infection that leads to extensive necrosis of the subcutaneous tissue and fascia. It is most commonly caused by group A streptococci and a mixed facultative and anaerobic flora. Recently, there have been an increasing number of cases of necrotizing fasciitis caused by community-acquired methicillin-resistant Staphylococcus aureus. Risk factors include diabetes mellitus, intravenous drug use, and peripheral vascular disease. The infection often arises at a site of minimal trauma, and the physical findings initially are minimal compared with the severity of pain and fever. The mortality rate for necrotizing fasciitis is between 15% and 34% but rises to as high as 70% if toxic shock syndrome is present. Wide surgical debridement of the affected tissue is necessary, and without surgery, the mortality rate is near 100%. A high index of clinical suspicion is important for selecting the appropriate antibiotic therapy and early consultation of surgery. The initial antibiotics should cover the typical organisms and include vancomycin 1 g IV every 12 hours, clindamycin 600 mg IV every 6ľ8 hours, and gentamicin 5 mg/kg/day intravenously.
IV-4. The answer is B. (Chap. 121) Cat bites are the most likely animal bites to lead to celluli-tis because of deep inoculation and the frequent presence of Pasteurella multicoda. In an immunocompetent host, only cat bites warrant empirical antibiotics. Often the first dose is given parenterally. Ampicillinľsulbactam followed by oral amoxicillinľclavulanate is effective empirical therapy for cat bites. However, in an asplenic patient, a dog bite can lead to rapid overwhelming sepsis as a result of Capnocytophaga canimorsus bacteremia. These patients should be followed closely and given third-generation cephalosporins early in the course of infection. Empirical therapy should also be considered for dog bites in elderly adults, for deep bites, and for bites on the hand.
IV-5. The answer is A. (Chap. 122) Immunization programs have the goals to control, eliminate, and eradicate disease. Disease control refers to decreases the impact of a specific illness on both health-related and societal outcomes. Examples of vaccinations that have lead to improved control of disease include the pneumococcal and influenza vaccines. Elimination can have two meanings. The first definition is to have zero cases in a defined geographic area. A second meaning is to reduce or eliminate the indigenous sustained transmission of an infection in a specific geographic area. In 2010, vaccine programs had eliminated measles, rubella, poliomyelitis, and diphtheria in the United States, although increasing numbers of cases of measles have been reported is some parts of the United States because of incomplete vaccination in children. Disease eradication is the most difficult goal to achieve. A disease can be considered eradicated when its elimination can be sustained without ongoing interventions. The only disease that has been globally eradicated at this point is smallpox. Poliomyelitis has been eradicated in most of the world although Afghanistan, Pakistan, India, and Nigeria continue to have ongoing transmission of the disease.
IV-6. The answer is B. (Chap. 122) Pneumococcal vaccination has been recommended for all individuals at any age with a variety of chronic medical conditions, including chronic respiratory disease, chronic heart disease, chronic liver failure, diabetes mellitus, asplenia, and chronic kidney disease. Determining when to revaccinate individuals has been somewhat controversial. The current recommendations are to revaccinate individuals ages 19 to 64 5 years after the initial vaccine if they have chronic renal failure or nephrotic syndrome, asplenia, or other immunocompromising conditions. All other individuals should receive a one-time revaccination at age 65 years and older if they were vaccinated 5 or more years previously and younger than 65 years old at the time of original vaccination.
IV-7. The answer is C. (Chap. 122) The varicella-zoster vaccine is a live virus vaccine that was recently introduced for prevention of shingles in older adults. The current recommendation is all adults older than 60 years be offered the zoster vaccine regardless of whether they report a childhood history of chickenpox. As this is a live virus vaccine, it cannot be administered to anyone who has severe immunodeficiency. Specific recommendations for whom the zoster vaccine is contraindicated include:
2. Anyone younger than 60 years
3. Patients with leukemia, lymphoma, or other malignant neoplasms affecting the bone marrow. If a patient is in remission and has not received chemotherapy or radiation therapy within 3 months, the vaccine can be given.
4. Individuals with AIDS or HIV with a CD4+ count <200/μL or ≤15% peripheral lymphocytes
6. Anyone with suspected cellular immunodeficiency (e.g., hypogammaglobulinemia)
7. Individuals receiving a hematopoietic stem cell transplant
8. Individuals receiving recombinant human immune mediators or modulators, especially antitumor necrosis factor agents
IV-8. The answer is E. (Chap. 122) Live-attenuated viruses are generally contraindicated as vaccines for immunocompromised hosts for fear of vaccine-induced disease. The most cited example of this is smallpox vaccine resulting in disseminated vaccinia infection. However, yellow fever vaccine is another example of a live virus vaccine. The other examples listed in this example are inactivated organisms (rabies, IM typhoid) or polysaccharide (meningococcal) and are therefore noninfectious. Oral typhoid vaccine is a live-attenuated strain, so the IM form is likely preferable in this host. Malaria prophylaxis currently involves chemoprophylaxis rather than vaccination. Although safe from an infectious standpoint, potential interactions with cyclosporine should be monitored.
IV-9. The answer is E. (Chap. 122) In recent years, rabies virus has been most frequently transmitted by bats in the United States. Usually a bite is noted but not always. Therefore, patients who have unexpected, unmonitored (i.e., while they are asleep) close contact with bats should be told to seek medical attention and likely vaccination. A bite is a clear indication for the most effective immunization strategy involving both active (inactivated virus vaccine) and passive (human rabies immunoglobulins) immune activation unless the offending bat is captured and found to be rabies negative with further testing. The vaccination schedule for nonimmunes is intensive, with doses at 0, 3, 7, 14, and 28 days. Although there has been at least one report of successful antiviral treatment of rabies, there is no indication for prophylactic antiviral therapy.
IV-10. The answer is E. (Chap. 123) When traveling abroad, it is important to plan ahead and consider the potential infectious agents to which one might be exposed. The Centers for Disease Control and Prevention and the World Health Organization publish guidelines for recommended vaccinations before travel to countries around the world. Before travel, it is certainly recommended that an individual be up to date on all routine vaccinations, including measles, diphtheria, and polio. Influenza is perhaps the most common preventable illness in travelers, and the influenza vaccine should be administered per routine guidelines. There are, however, very few required vaccinations in most countries. Yellow fever is one exception, and proof of vaccination is required by many countries in sub-Saharan Africa and equatorial South America. This is especially important for individuals traveling from areas where yellow fever is endemic or epidemic. The only other required vaccinations are meningococcal meningitis and influenza vaccination to travel in Saudi Arabia during the Hajj.
IV-11. The answer is E. (Chap. 123, http://wwwnc.cdc.gov/travel/destinations/haiti.htm. Malaria remains endemic in many parts of the world, and an estimated 30,000 travelers from the United States and Europe are infected with malaria during travel yearly. The areas of highest risk are in sub-Saharan Africa and Oceania with the lowest risk in South and Central America, including Haiti and the Dominican Republic. Chloroquine resistance is growing throughout the world and is especially notable in parts of South America, Africa, and Southeast Asia. However, in Haiti, the incidence of chloroquine resistant malaria is low. For a traveler to Haiti, the Centers for Disease Control and Prevention states that travelers have a choice of chloroquine, doxycycline, atovaquoneľproguanil, or mefloquine. In addition, travelers should be cautioned to use appropriate techniques for malarial prevention, including
protective clothing, DEET-containing insect repellants, permethrin-impregnated bednets, and screened sleeping accommodations, if possible.
IV-12. The answer is E. (Chap. 123) Individuals with HIV are generally considered at high risk of infectious complications when traveling abroad. However, individuals who have no symptoms and a CD4+ count greater than 500/μL appear to be at no greater risk than individuals without HIV infection. Before travel, it is important to research the travel requirements for the specific country of travel. Many countries routinely deny entry for HIV-positive individuals for prolonged stays, and proof of HIV testing is required in many countries for stays longer than 3 months. Consular offices should be contacted before travel to determine if any special documentation is required. HIV-infected travelers should have all routine immunizations before travel, including influenza and pneumococcal vaccinations. The response rate to influenza in an asymptomatic HIV-positive person is greater than 80%. Generally, live-attenuated viruses are not given to HIV-infected individuals. However, because measles can be lethal in those with HIV, this vaccine is recommended unless the CD4+ count is less than 200/μL, and the expected response rate would be between 50% and 100%. In contrast, the live yellow fever vaccine is not given to HIV-infected travelers, and individuals with CD4+ counts below 200/μL should be discouraged from traveling to countries with endemic yellow fever. Some countries in sub-Saharan Africa require yellow fever vaccination. However, because this patient is traveling from a low-risk area, a medical waiver would likely be issued.
FIGURE IV-13 (see Color Atlas)
IV-13. The answer is E. (Chap. 124) The etiologic agents of infective endocarditis vary by host (see Figure IV-13). Community-acquired native valve endocarditis remains an important clinical problem, particularly in elderly people. In those patients, streptococci (Viridans spp., S. gallolyticus, other nonľ group A and other group streptococci, and Abiotrophia spp.) account for approximately 40% of cases. Staphylococcus aureus (30%) is next most common. Enterococci, HACEK group, coagulase-negative, and culture-negative cases each account for less than 10% of community-acquired native valve cases. In health careľassociated, injection drug useľassociated, and greater than 12-month-old prosthetic valve endocarditis, S. aureus is most common. Coagulase-negative staphylococcus is the most common organism in prosthetic valve endocarditis less than 12 months. Enterococci cause endocarditis in approximately 10% to 15% of cases in health careľassociated, 2- to 12-month prosthetic valve, and injection drug use cases. Culture-negative endocarditis accounts for 5% to 10% of cases in all of the aforementioned clinical scenarios.
IV-14. The answer is B. (Chap. 124) The Duke criteria for diagnosis of infective endocarditis are a set of major and minor clinical, laboratory, and echocardiographic criteria that are highly sensitive and specific. The presence of two major criteria, one major criterion and three minor criteria, or five minor criteria allows a clinical diagnosis of definite endocarditis (see Table IV-14 ). Evidence of echocardiographic involvement as evidenced by an oscillating mass (vegetation) on a valve, supporting structure, or implanted material; an intracardiac abscess or partial dehiscence of a prosthetic valve; or a new valvular regurgitation are major criteria in the Duke classification. An increase or change in preexisting murmur by clinical examination is not sufficient. Transthoracic echocardiography is specific for infective endocarditis but only finds vegetations in about 65% of patients with definite endocarditis. It is not adequate for evaluation of prosthetic valves or for intracardiac complications. Transesophageal echocardiography is more sensitive, detecting abnormalities in more than 90% of cases of definite endocarditis.
TABLE IV-14 The Duke Criteria for the Clinical Diagnosis of Infective Endocarditisa
1. Positive blood culture Typical microorganism for infective endocarditis from two separate blood cultures
Viridans streptococci, Streptococcus gallolyticus, HACEK group, Staphylococcus aureus, or Community-acquired enterococci in the absence of a primary focus, or
Persistently positive blood culture, defined as recovery of a microorganism consistent with infective endocarditis from:
Blood cultures drawn >12 h apart; or
All of 3 or a majority of ≥4 separate blood cultures, with first and last drawn at least 1 h apart
Single positive blood culture for Coxiella burnetii or phase I IgG antibody titer of >1:800
2. Evidence of endocardial involvement Positive echocardiogramb
Oscillating intracardiac mass on valve or supporting structures or in the path of regurgitant jets or in
implanted material in the absence of an alternative anatomic explanation, or
New partial dehiscence of prosthetic valve, or
New valvular regurgitation (increase or change in preexisting murmur not sufficient) Minor Criteria
1. Predisposition: predisposing heart condition or injection drug use
5. Microbiologic evidence: positive blood culture but not meeting major criterion as noted previouslyc or serologic evidence of active infection with organism consistent with infective endocarditis
aDefinite endocarditis is defined by documentation of two major criteria, of one major criterion and three minor criteria, or of five minor criteria. See text for further details.
bTransesophageal echocardiography is recommended for assessing possible prosthetic valve endocarditis or complicated endocarditis.
cExcluding single positive cultures for coagulase-negative staphylococci and diphtheroids, which are common culture contaminants, and organisms that do not cause endocarditis frequently, such as gram-negative bacilli.
Source: Adapted from Li JS et al: Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis. Clin Infect Dis 30:633, 2000, with permission from the University of Chicago Press.
IV-15. The answer is C. (Chap. 124) The recommendations for prophylaxis to prevent infective endocarditis have undergone change recently with a change to recommending it for fewer patients. The most recent American Heart Association guidelines (Circulation 116:1736, 2007) reverse many of the former recommendations based on indirect evidence suggesting that benefit is minimal and is not supported by cost-benefit or cost-effectiveness studies. Current recommendations advise prophylactic antibiotics only for those at highest risk for severe morbidity or mortality from endocarditis undergoing manipulation of gingival tissue or periapical region of the teeth, perforation of the oral mucosa, or a procedure on an infected site. Prophylaxis is not advised for routine gastrointestinal or genitourinary procedures. High-risk patients include those with prior endocarditis, prosthetic heart valves, unrepaired cyanotic congenital heart disease lesions, recently (<6 months) repaired congenital heart lesions, incompletely repaired congenital heart disease lesions, and valvulopathy after cardiac transplant. The British Society for Antimicrobial Chemotherapy does recommend prophylaxis for at-risk patients undergoing selected gastrointestinal or genitourinary procedures; however, the National Institute for Health and Clinical Excellence in the United Kingdom advised discontinuation of the practice (http://www.nice.org.uk/guidance/cg64).
IV-16. The answer is A. (Chap. 124) This patient has culture-negative endocarditis, a rare entity defined as clinical evidence of infectious endocarditis in the absence of positive blood cultures. In this case, evidence for subacute bacterial endocarditis includes valvular regurgitation; an aortic valve vegetation; and embolic phenomena on the extremities, spleen, and kidneys. A common reason for negative blood cultures is prior antibiotics. In the absence of this, the two most common pathogens (both of which are technically difficult to isolate in blood culture bottles) are Q fever, Coxiella burnetii (typically associated with close contact with livestock), and Bartonella spp. In this case, the patientĺs homelessness and body louse infestation are clues for Bartonella quintana infection. Diagnosis is made by blood culture about 25% of the time. Otherwise, direct polymerase chain reaction of valvular tissue, if available, or acute and convalescent serologies are diagnostic options. Empirical therapy for culture-negative endocarditis usually includes ceftriaxone and gentamicin with or without doxycycline. For confirmed Bartonella endocarditis, optimal therapy is gentamicin plus doxycycline. EBV and HIV do not cause endocarditis. A peripheral blood smear would not be diagnostic.
IV-17. The answer is D. (Chap. 124) Although any valvular vegetation can embolize, vegetations located on the mitral valve and vegetations larger than 10 mm are greatest risk of embolizing. Of the
answer choices, C, D, and E are large enough to increase the risk of embolization. However, only choice D demonstrates the risks of both size and location. Hematogenously seeded infection from an embolized vegetation may involve any organ but particularly affects those organs with the highest blood flow. They are seen in up to 50% of patients with endocarditis. Tricuspid lesions lead to pulmonary septic emboli, which are common in injection drug users. Mitral and aortic lesions can lead to embolic infections in the skin, spleen, kidneys, meninges, and skeletal system. A dreaded neurologic complication is mycotic aneurysm, focal dilations of arteries at points in the arterial wall that have been weakened by infection in the vasa vasorum or septic emboli, leading to hemorrhage.