Cases Flashcards
(95 cards)
1
Q
A 75-year-old man is brought by his family for evaluation of behavioral changes. The man was previously highly functional but has developed confusion, inattentiveness, and insomnia that have progressively worsened over a month. The family also notes his gait is unstable. On exam, he has signs of cerebellar ataxia and myoclonus. Workup including CT, MRI/MRA, and toxicology screen is unremarkable, and Gram stain, viral PCR, and cytology of CSF are unrevealing. Over the next month, the patient has worsening myoclonic jerking and cognitive impairment, and on the fourth week, he dies. Autopsy reveals myriad microscopic holes throughout the cerebral cortex giving a sponge-like appearance.
A
CJD
2
Q
A patient from a tropical village has an enormously swollen scrotum and lower extremity. The skin around the swelling has become scaly and thick. The patient remembers feeling enlarged nodes in the groin months before the swelling began, but because of poor health resources in the area, he never saw a physician. Samples of his blood drawn at night show wormlike organisms under a microscope. A visiting doctor strongly recommends that the patient and other villagers sleep with a mosquito net to prevent more infections.
A
Wucheria Bancrofti
3
Q
A traveling physician visits a remote riverside village in a South American country and discovers that most of the older village inhabitants are blind. On physical exam of some of the members, she notes skin nodules and hyperpigmented rashes. To prevent other village members from becoming blind, she administers donated ivermectin to many people in the village and urges mosquito control.
A
Oncocherca Volvulus
4
Q
An elderly man develops low-grade fever and signs of endocarditis over a period of 2 weeks. Following blood culture, his doctor also becomes concerned about possible colon cancer.
A
Group D Streptococcus Bovis
5
Q
Most common causes of meningitis in 60 yrs:
A
S. pneumoniae
Gram negative rods
Listeria
6
Q
A middle-aged woman presents with low-grade fever and general malaise. Physical exam reveals Janeway lesions, Osler’s nodes, Roth’s spots, and splinter hemorrhages under her fingernails. Echocardiogram indicates vegetations on the mitral valve. In the doctor’s office, she recounts a dentist appointment a few weeks ago and several bouts of sore throat as a child.
A
Streptococcus Viridans group -> strep mutans (normal mouth flora) and strep intermedius (brain or abdominal abcesses)
7
Q
A mother brings her 2-month-old infant to the hospital because he exhibits fever, convulsions, irritability, and poor eating.
The pediatrician-in-training notes a widespread rash and a stiff neck on physical exam. She orders a spinal tap that reveals low glucose, ↑ PMNs, ↑ protein, and Gram rods with “tumbling” motility in cultures. Upon further questioning, the pediatrician discovers that the mother does not breast-feed and feeds her baby with fresh cow’s milk.
A
Listeria Monocytogenes
8
Q
A young immigrant girl goes to the doctor complaining of a sore throat and difficulties in breathing and swallowing. Her voice is unusually nasal and a large gray mucous film is noticed on the oropharynx. The patient also exhibits ST-T wave changes on an electrocardiogram and a slight paralysis of her tongue. Her blood pressure is low, her lungs edematous, and her neurological examination shows cranial nerve problems. Her physician begins immediate treatment and orders a potassium tellurite culture to confirm his worst suspicions.
A
Corynebacterium Diptheriae
9
Q
Most common causes of meningitis 6–60 yrs:
A
N. meningitidis Enterovirus (aseptic meningitis)
S. pneumoniae
10
Q
A 2-year-old girl returns to her pediatrician with fevers, recurrent ear pain, and new onset yellow discharge from the right ear. She had been diagnosed earlier in the week with right otitis media and treated with amoxicillin. The pediatrician correctly suspects that a beta-lactamase–producing organism is causing the infection, and had he gram stained the ear discharge, he would have found gram-negative diplococci.
A
Moraxella catarrhalis
11
Q
A woman who recently returned from a trip to South America complains of a persistent high fever, malaise, and constipation that has lasted for over a week. She recalls that the fever began slowly and climbed its way up to the current 41°C. A physical exam reveals that she has an enlarged spleen and a generally tender abdomen with red macules. The physician asks for a stool sample to complete the diagnosis.
A
Salmonella Typhii
12
Q
A veterinary school student complains to the doctor of diarrhea and abdominal tenderness. He is certain that these symptoms followed nausea and vomiting the day before. He admits that he may have caused himself this misery by excessively playing with his turtle.
A
Salmonella Enterididis
13
Q
A woman returns to the doctor because of an annoying and persistent urinary tract infection. The woman’s complaint of dysuria motivates more diagnostic tests, revealing the presence of large radiopaque stones in the urinary tract. The woman also provides several urine samples, which are consistently high in pH.
A
Proteus Mirabilis > swarming motility, urease positive
Weil-Felix Reaction utilizes the O antigen of Proteus bacteria to diagnose Ricketsia infections
14
Q
A man visiting India arrives in the emergency room with signs of severe dehydration: He is thirsty, has decreased skin turgor, tachycardia, and somnolence. He abruptly began to suffer from diarrhea this morning and complains about the magnanimous watery volumes he is excreting. He has no fever, and the doctor treats with fluid and electrolytes.
A
Vibrio Cholera -> gram negative, polar flagella comma shaped rod
-Cholera toxin is carried on bacteriophage.
15
Q
A man and his two sons just returned from a vacation on their relative’s farm. All three arrive complaining of bloody diarrhea. The youngest son becomes well spontaneously. The older son complains of right flank pain, while the father starts to notice tenderness in his joints. One surgeon, worried about appendicitis in the older son, performs the initial incisions and discovers a normal appendix but an inflamed colon. After also observing swollen mesenteric lymph nodes during surgery, he makes a diagnosis explaining the symptoms in all three patients.
A
Yersinia Enterocolitica
- gram negative rod, motile at 25 degrees but not at 37
- causes septic arthritis as well
16
Q
An aged man comes to the hospital complaining of upper abdominal pains, which become worse after a meal. Knowing
the patient’s history, the doctor is about to prescribe an H2 blocker and send the patient on his way, just as he has done for many patients before this one. However, biopsy of the stomach mucosa and urease breath test lead the doctor to prescribe antibiotics in addition to treatment for peptic ulcer.
A
H. Pylori
- urease positive
- Chronic H. pylori gastritis is associated with gastric adenocarcinoma and MALT lymphoma.
17
Q
A man with fever, muscle pains, and headache feels no need to go to the doctor until about 1 day later, when he develops diarrhea and abdominal pain as well. The abdominal pain is so severe that his physician fears appendicitis until learning that the man may have had unpasteurized milk in the past week. A definitive diagnosis is made by growth on stool culture at 42°C, microaerophilic conditions.
A
Campylobacter Jejuni
- invades terminal ileum/colon
- associated with Guillian-Barre (ascending paralysis)
18
Q
gram-negative rod anaerobes, are found in the upper airways (“above the diaphragm”) and can cause pulmonary
abscesses that can be treated with penicillin G.
A
Bacteriodes melaninogenicus and Fusobacterium nucleatum
19
Q
A 1-year-old infant develops a fever but really begins to alarm her parents when she seems unusually drowsy. The parents bring her to the hospital and the doctor notices neck rigidity and occasional seizures. The doctor identifies an organism in the infant’s cerebrospinal fluid that requires both hemin and NAD to grow. The infant recovers after ceftriaxone is administered but seems to have acquired a partial hearing loss.
A
Haemophylis Influenzae, Type B is encapsulated
shows + Quellung Test (capsule)
- coccobacilli
- decreased incidence due to HiB vaccination conjugated with diptheria toxin
20
Q
HACEK organisms (Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella species)
A
gram-negative bacilli that are part of normal oral flora and can infect heart valves. They are the most common gram-negative cause of endocarditis in non-IV drug users.
21
Q
A 67-year-old man with a history of heavy smoking comes to the doctor complaining of “the flu.” He has a fever, loss of appetite, headache, chest pain, and a mild cough producing little sputum. The doctor believes that the watery diarrhea that the man also suffers from is related. Sputum sample reveals many neutrophils but no bacteria. CXR reveals nodular infiltrates. Serum tests are negative for cold agglutinins.
A
Legionella pneumophila is an important cause of community-acquired pneumonia in elderly smokers. Severe atypical pneumonia
- Gram stains poorly, visualize with silver stain. Coccobacilli
- intracellular
- culture on charcoal yeast extract with iron and cysteine
22
Q
A doctor is struggling to diagnose a woman’s flulike illness. She complains of a fever that rises during the day and peaks after dinner, fatigue, spinal tenderness, and loss of appetite. Her lymph nodes are enlarged in physical exam. The doctor has trouble narrowing down the possible etiologies until he hears that the woman tasted goat cheese at a local French village a month before the onset of her symptoms.
A
Brucella
-Gram - , coccobacilli, facultative intracellular
Osteomyelitis is the most common complication.
Brucellosis in the U.S. most commonly occurs from ingestion of imported goat cheese that is poorly pasteurized.
23
Q
A woman from Arkansas presents to the doctor with a small but persistent black ulcer on her arm. The area near the ulcer is erythematous and tender. Her axillary lymph nodes on the same side are enlarged. She believes the ulcer may be related to a tick bite that occurred on her arm while tending to her rabbit farm.
A
tularemias (site-specific infection lymphadenopathy): ulceroglandular tularemia
oculoglandular tularemia
pulmonary tularemia
typhoidal tularemia
Diagnosis:
skin test (DTH response)
serology
cultures rarely performed because organism highly infectious
24
Q
A homeless man enters the hospital with wasting and fever. He has had a chronic cough for several months producing bloody sputum as well as night sweats. CXR reveals cavitations with air-fluid levels in the apex of his left lung. Diagnosis is confirmed by an acid-fast stain of sputum.
A
Mycobacterium Tuberculosis
25
A sexually active man seeks medical attention for a wart-like lesion developing on his genitals. He recalls a painless ulcer
on his genitals over a month ago, but now is concerned because papules are appearing in his armpits and palms as well. Recently, he has also suffered fever and chills, and the doctor notices a nontender, generalized lymphadenopathy. The doctor questions the man about the health of his sexual partners. A dark-field analysis confirms the doctor’s suspicion of the etiology and the patient is prescribed penicillin G.
What is this patient at risk for down the road?
What would a congenital infection with this bacteria cause?
Treponema pallidum
- Will begin to develop condyloma lata (2ndary syphillis)
- gummas, neurosyphylis, tabes dorsalis, Argyl Robertson pupil, aortic aneurysm
Congenital syphilis: CN VIII deafness, mulberry molars, saber shins, saddle nose, Hutchinson’s incisors
26
Treponema pallidum subspecies cause nonvenereal skin ulcers and skin/bone gummas:
T. pallidum endemicum → endemic syphilis (common
in Africa, Middle East)
T. pallidum pertenue → Yaws (gummas disfigure face)
T. pallidum carateum → Pinta (red → blue → white lesions, limited to Latin America).
27
A woman seeks medical attention for a skin rash expanding on her arm over several days. Her doctor notes an annular, red rash with a clear area in the center. The woman also complains of a fever, headache, arthralgias, and stiffness of the neck following the onset of the rash by a week. When asked if bitten by any insects, the woman cannot answer definitively, but she does remember seeing a tick on her sleeping bag during a camping trip to Connecticut last month. The doctor prescribes doxycycline and checks the woman’s electrocardiogram to ensure no heart problems have developed as a result of her illness.
What would this organism show on skin biopsy?
Coinfections?
Borellia burgdorferi
spirochete, motile under darkfield microscopy
diagnosis via serology
- possible coinfection w/ Babesiosis (both xferred via Ixodes tick)
- Babesiosis causes hemolytic anemia and fever, asymptomatic usually in immunocompetent patients.
28
A farmer comes to the EW with a 1-week history of flu-like symptoms with photophobia. His severe headache, cough, and myalgias suggest to the physician some kind of respiratory infection. However, more careful physical exam reveals conjunctival suffusion and macular rash. Lab findings include elevated serum bilirubin, alkaline phosphatase, aminotransferases, and creatine phosphokinase. With this clinical picture and lab results, the physician prescribes penicillin G immediately. His suspicions are confirmed later when a spirochete is isolated from the patient’s blood.
Leptospira interrogans
29
A young woman at an army base thinks she has a cold and goes to her doctor. She complains of malaise, chills, sore throat, and dry cough. CXR shows interstitial infiltrate more severe than suggested by her symptoms. Laboratory tests indicate that the woman’s serum was capable of agglutinating erythrocytes when incubated at 4°C. The doctor prescribes erythromycin.
How is this diagnosed?
Mycoplasma Pneumonia
"atypical” pneumonia (walking pneumonia)
cold hemagglutination
no cell wall, fried-egg appearance (2–3 wk culture on Eaton’s agar) serology
30
Two obligate intracellular parasites (require host ATP for energy):
Chlamydiae
Rickettsiae
Chlamydiae replicate within
inclusion bodies, Rick ettsiae replicate freely in cytoplasm.
31
A woman is brought to the EW complaining of vaginal discharge and RUQ abdominal pain. On history, the patient reports having many sexual partners. Pelvic exam reveals cervical motion tenderness, and labs of vaginal discharge detect numerous PMNs but no organisms on Gram stain. The doctor makes a diagnosis based on these findings and administers doxycycline and ceftriaxone. Later, surgeons, concerned about the patient’s abdominal pain, rule out cholecystitis by imaging, but laparoscopy reveals adhesions around the patient’s liver capsule.
How is this diagnosed?
Chlamydia Trachomatis
Nucleic acid amplification (PCR, transcription-mediated amplification)
visualize intracytoplasmic inclusions: iodine stain (inclusions contain glycogen), Giemsa stain serology
cultured in cell lines (intracellular growth)
32
A 22-year-old student presents with a nonproductive cough, fever, and sore throat. CXR demonstrates diffuse interstitial infiltrate. Sputum Gram stain shows many PMNs but no organisms, and a Giemsa stain reveals intracytoplasmic inclusions in epithelial cells. Doxycycline treatment is begun.
Chlamydia Pneumoniae
33
A 10-year-old boy in Virginia presents with a rash, fever, and a severe headache that began several days ago. The rash began on his palms and soles and has now spread centrally to his trunk. His pediatrician also notes conjunctival redness, and lab studies show proteinuria. The boy’s history is significant for a hike in the woods a week ago. The child is given tetracycline, and his diagnosis is confirmed by a Weil-Felix test.
Where does this organism specifically target?
Where do these organisms replicate?
Rickettsia Rickettsii
targets endothelial cells
obligate intracellular organism that replicates in the cytoplasm
34
A Kosovo refugee sees a volunteer camp doctor complaining of a rash spreading outward from his trunk but sparing his palms and soles. Two days ago, he experienced abrupt onset of fever, headaches, and confusion. On physical exam, the doctor discovers lice in the man’s hair. The doctor treats with a delousing regimen and tetracycline. Were he at a hospital, he might confirm the diagnosis with a Weil-Felix test.
How is this organism spread? what is the reservoir?
How do you differentiate between epidemic and RMSF?
What causes the endemic infection of tis organism, in South Texas and California?
Rickettsia Prowarzekii
- human-to-human spread via louse responsible for epidemics during war
- flying squirrel is the reservoir
```
Epidemic typhus (R. prowazekii) causes a rash that spreads outwardly but avoids the palms, soles, and face vs. Rocky
Mountain Spotted Fever (R. rickettsii) that causes a rash that spreads proximally from the palms and soles.
```
-R. typhi: fleas transmit from rodents to humans → endemic typhus found in South Texas and California
35
A cattle farmer goes to his doctor complaining of a mild cough and fever. He says that the fever began abruptly several days ago. His occupation as cattle slaughterer leads the doctor toward a diagnosis, and tetracycline is administered. The diagnosis is confirmed by serology and a negative Weil-Felix test.
How does this differ from other rickettsia infections?
Coxiella Burnetti causes fever, atypical pneumonia.
-may lead to hepatitis,endocarditis
In contrast to other Rickettsial disease:
C. burnetii does not require arthropod transmission because it can survive extracellularly as a spore.
C. burnetii does not cause rash.
36
A woman in India complains of fever, muscle pains, and weakness of her trunk, abdomen, and legs. This morning, she notes difficulty in swallowing and neck pain, which prompts her to come to the hospital. Physical exam reveals fasciculations and flaccid paralysis of the lower limbs and trunk. Breathing seems to be troubled. A CSF analysis reveals lymphocytosis, PMNs, and normal glucose and protein levels. The physician confirms the diagnosis by checking the woman’s vaccination history and prepares respiratory support in case her breathing difficulties worsen.
What kind of virus is this?
Poliovirus
Picovirus, also an enterovirus
-icosahedral capsid, naked virus
37
A young man presents with chest pain, dyspnea, and early signs of heart failure. His history shows he had an upper respiratory infection 3 weeks ago. Examination reveals tachycardia and a gallop rhythm (S3), while ECG shows evidence of a conduction defect with nonspecific ST-T changes. Echocardiogram is ordered and shows cardiomegaly with contractile dysfunction.
The doctor makes a viral diagnosis by serology and admits the patient for monitoring, assuring the patient that he will likely recover completely.
What family is this virus in?
What other serious disease can this virus cause?
Cocksackie B
-causes pleurodynia
- Cocksackie is an enterovirus, which is a member of Picovirus (neg sense ssRNA)
- nonenveloped
Naked viruses -> P.C.R (Pico, Calci, Reo)
Enteroviruses are the #1 cause of aseptic meningitis
38
A Boy Scouts troop master calls the doctor asking about symptoms that have developed in 7 of his 20 Scouts shortly after a camping trip. The ill boys complain of fever, nausea, loss of appetite, and vomiting. The Scout master also notes a yellow hue in some of the boys, especially visible in their eyes. Two of the affected boys are brought to the hospital where their urine is noted to be dark and their feces pale. Liver enzyme assays reveal an elevated ALT and AST level. The physician confirms the diagnosis with an assay of serum IgM and then assures the master and his Scouts that the illness will completely go away in several weeks.
How would this physician determine that this infection is no longer active?
Hepatitis A
IgG Anti-HAV
39
A woman presents with a runny nose, sneezing, an irritable throat, and a slight fever. She suffers similar symptoms every year, often at the same time as other members of her family. Her symptoms go away within a week, except for the nasal discharge that persists for a few more days.
What family is this a member of?
Rhinovirus, member of the Picovirus family (naked)
40
Thirteen people attending an oyster dinner abruptly develop nausea and abdominal pains 2 days later. Soon after the onset of pain, they begin to vomit and some also have diarrhea.
Norwalk virus is a major cause of group-related or institutional diarrhea.
41
A man goes to India on a hiking trip in the Himalayas. Upon returning, he develops nausea, vomiting, malaise, and headache. His doctor notices jaundice and hepatomegaly on physical exam, and labs detect increased AST, ALT, and direct serum bilirubin levels. Immunization records show that the man had received HAV and HBV vaccines before leaving. The symptoms are traced back to a shared water supply along the hiking route.
What family is this virus in?
Hepatitis E
member of Flavivirus
42
A mother brings her 3-year-old son to the doctor after severe bouts of vomiting and diarrhea for the past 2 days. The diarrhea is watery, although the mother denies seeing any blood in it. The doctor makes a diagnosis by an ELISA on the child’s stool and assures the mother he will be fine with good rehydration.
Rotavirus (member of Reovirus)
Rotaviruses are the most common cause of infectious diarrhea in infants and young children.
Reoviruses are the only RNA viruses that are double-stranded.
43
Late July, a father brings his daughter to the emergency ward for fever, vomiting, and strange behavior that developed the
day before. The EW physician notes that the daughter has head and neck pains and is photophobic. A quick neurological
exam reveals hemiparesis and some cranial nerve deficits. The physician asks the father about any recent mosquito bites she may have had, and the father affirms that they are swarmed by mosquitoes in their Florida home. The physician fears a grave diagnosis with a high mortality rate or at least a slow recovery lasting weeks. This diagnosis is confirmed by detection of virus, PMN pleocytosis, normal glucose, and slightly ↑ proteins in the CSF.
Togavirus -> alpha virus -> EEE, WEE, VEE
-main symptoms of the encephalitis -> headache, meningitis, photophobia
44
A woman goes to her doctor complaining of a red rash on her face. She reports having a fever that resolved just before the rash appeared. During a physical exam, the doctor notes that the rash has spread to the arms. Swollen lymph nodes are felt in the cervical region and behind the ears. The doctor inquires about the woman’s vaccination record and makes a diagnosis to be confirmed by serological studies. The doctor also makes sure that the woman is not pregnant. The woman is relieved to know the rash will go away in several days, although she may experience arthritis for some time thereafter.
What virus is causing thes symptoms? What family is this virus in?
Had this been a congenital infection, what birth defects could likely have been present?
Rubella (german measles), member of the togaviridae family
Cardio -> pulm art stenosis, patent ductus, etc
Eyes -> cataracts, retinitis
CNS -> microcephaly, deafness, mental retardation
45
A 75-year-old man from New York is brought to the ED after reporting 1 week of fever, headache, nausea, and muscle ache. On exam, he appears confused and has a course tremor in his hands. CT and MRI are unrevealing. A lumbar puncture is per- formed, and CSF analysis demonstrates elevated protein, normal glucose, and lymphocytosis. His family reports that he was visiting them for the summer, but they have avoided the outdoors after several dead crows were found in their neighborhood.
In general, how do most patients present with this disease?
How is this disease diagnosed? What is the most sensitive way to detect this disease?
What family is this virus is?
West Nile Virus (flavivirus)
-xmitted via mosquitos (birds also involved as hosts)
MOST are asymptomatic, while others will exhibit a maculopapular rash, and signs of neuroinvasive disease: aseptic meningitis, encephalitis with decreased consciousness, or dramatic motor weakness. Can mimic polio or guillian barre
Diagnosed via PCR of virus in culture, CSF
Most sensitive diagnostic is serum or CSF IgM IMPORTANT to order both a PCR of serum and to get antibody titers
Flavivirus
46
A diplomat plans to make a trip to Central America. However, just before leaving, his doctor receives a CDC report of jungle log cutters that have fallen ill with jaundice, instances of hemorrhage, and liver dysfunction. He insists that the diplomat be immunized against this infectious agent before traveling to the area.
What is the agent that causes this? what is the vector?
For a summer trip, a woman visits the tropics for a short time. One week upon returning, she shows signs of fever, headache, and pain behind the eyes and in the back and joints. She also notices a generalized rash forming. The doctor explains that the illness will pass but that a second infection by a similar agent might lead to more devastating symptoms.
What is the second infection? What is the particular type of agent that causes this more severe subtype?
First case: Yellow Fever (flavi)
-Aedes mosquito
Second case: Dengue fever (back and joint pain give it away)
More severe type is dengue hemorrhagic fever -> serotype 2. Causes hemorrhage, thrombocytopenia, and shock.
47
Feeling fatigued, a man visits his doctor. On physical examination, the patient has reduced liver size. After a thorough history, the doctor learns that the patient had jaundice 5 years ago following a car accident for which he was hospitalized and received a blood transfusion. The doctor is not surprised to see an elevated serum level of ALT in his blood workup and awaits an ELISA to differentiate the causes of this illness.
Hepatitis C (chronic hepatitis)
increased risk of hepatocellular carcinoma
48
A 57-year-old Caribbean woman seeks the attention of her physician when her legs “do not seem to function appropriately.” She tells the physician that she began to feel a stiffness in her left leg and then both legs over the past few weeks, as well as occasional back pain. A neurological exam reveals slight sensory losses, hyperreflexia, and extensor plantar responses in both legs; no cognitive or cranial nerve dysfunction is noted. The physician requests an MRI, which reveals lesions in the white matter of the brain and spinal cord as well as in the paraventricular gray matter of the brain. Although the woman does not have leukemia or lymphoma, the physician suspects a diagnosis that is confirmed by detection of specific antibodies in her CSF. He begins the patient on a regimen of glucocorticoids and explains that her symptoms may progress to paraplegia.
HTLV is involved in T cell leukemia and can also cause Tropical Spastic Paresis (which this case describes)
T cell leukemia from HTLV-1 is endemic to caribbean and Japan
49
A chronic drug user previously diagnosed with hepatitis B presents with a recurrence of symptoms, most notably yellow sclerae. Typical signs of chronic hepatitis—serum AST and ALT elevation, jaundice, hepatomegaly, splenomegaly—seem more severe in this patient. The physician suspects that hepatitis B is only part of his clinical picture and recommends treat- ment with -interferon to reduce the symptoms. The patient is informed that he is at risk for liver failure.
Hepatitis D (superinfection)
50
A recent college graduate has been camping in Arizona in a wooded area heavily populated with deer mice. He cuts his vacation short, however, when he develops a fever and begins vomiting. By the time he reports to the hospital 3 days later,
he is hypotensive, cyanotic, and tachypneic. Fearing shock, emergency physicians begin to administer fluids but stop this treatment when chest X-rays reveal interstitial pulmonary edema. The patient develops respiratory failure within 24 hours and dies by the second day of hospitalization. A diagnosis is confirmed by IgM serum assay and a lung biopsy.
What agent? What family is this agent in? How is this agent transmitted?
Hantavirus (bunyavirus family)
caused by aerosolized transmission from mouse feces
51
A 34-year-old woman, during a visit to Nigeria, develops a fever over the course of the fifth week of her visit. The fever progresses to headache, nausea, and diarrhea. By the time she arrives at a hospital, her physician notes signs of pericardial effusion. Furthermore, a diarrhea sample contains blood indicating GI hemorrhage. The physician is quite familiar with the symptoms in that region of Nigeria. He explains that she likely contracted her illness from rodents or from someone who had come into close contact with rodents. The woman is required to remain hospitalized because she is considered contagious.
What agent, what family?
Lassa Virus (arenavirus)
52
A child presents with altered mental status and seizures. During the exam, the doctor notes epistaxis, gum bleeding, and right lower quadrant pain. Further questioning reveals that 3 weeks ago, the child had general weakness, myalgias, fever, and a cough. His mother had similar flu-like symptoms a week before and treated both herself and her child with aspirin. The doctor suspects that the child’s serious symptoms would have been prevented had the mother given Tylenol instead of aspirin to her child. Liver function and blood tests are ordered immediately.
What are the virulence factors for this agent, and how do they work?
Infuenza virus (orthomyxovirus)
Reyes Syndrome after aspirin (brain and liver dmg)
HA -> binds sialic acid receptors to infect RBCs
NA -> cleaves mucin to expose the sialic acid receptor, also helps the virus spread by cleaving the sialic acid receptor after HA has bound
53
A father brings his baby girl to the EW in the middle of the night. Before leaving the house, the girl had a high fever, nasal discharge, and barking cough. Now, however, the barking cough seems to have disappeared. The doctor on call realizes that the cool night air probably relieved the child’s symptoms before she arrived at the hospital. Because no inspiratory stridor is noted on physical exam, the doctor sees no need to give the girl corticosteroids and assures the father that the illness will go away in a few days.
What are the two terms that are used to characterize this infants cough?
What virulence factors does this agent have?
Parainfluenza virus
HA, NA, and F protein
Croup and laryngotracheobronchitis
54
An infant girl who was hospitalized and released for a previous illness returns to the hospital 2 days later with fever, cough, and wheezing. The parents, both asthmatic, think their child is now developing asthma. A CXR reveals hyperinflated lungs with infiltrates. The doctor is convinced that this is a nosocomial viral infection, as many other children admitted to the hospital develop the same symptoms. He transfers the baby to the neonatal intensive care unit, where she is treated with aerosolized ribavirin.
What virulence factors are expressed by this virus
RSV
F protein ONLY, no HA or NA is expressed
55
What are Warthin-Finkeldey cells? What do they indicate?
Pathognomonic for Measles -> multinucleated giant cells with inclusion bodies in nucleus and cytoplasm
56
An anthropologist is brought to the emergency room one evening for high fever, vomiting, headache, confusion, and bloody diarrhea. He explains that he had cut an expedition in Zaire short and returned to the U.S. when he developed the high fever. Physical exam is remarkable for a 40°C fever, slight hypotension, a nonpruritic rash on the neck and arms, and a nosebleed. Upon reviewing the history, the ER physicians order an immediate hospital quarantine of the anthropologist and his family. They then investigate his exact itinerary in Zaire and all his close contacts in the past 3 weeks. The next day, the patient dies with disseminated intravascular coagulation.
What category of bioterrorism agents is this in?
Ebolavirus (Filoviridae)
Category A
57
A middle-aged man, diagnosed with AIDS, presents to the EW complaining of “seeing double.” Physicians perform a complete neurological examination and further discover problems in talking, coordinating movements, and remembering things. Imaging of the brain reveals deep densities localized to the white matter that span the frontal, parietal, and temporal lobes. The doctors make an infectious disease diagnosis and discuss how to best tell the patient about his very grave prognosis.
What kind of virus is this, what family?
JC Polyoma virus
Papova family, dsDNA virus
58
A mother brings her 4-year-old child to the doctor because of a swollen, red right eye. She is frustrated, complaining that the symptoms appeared after she had taken her child to a local ophthalmologist. The doctor diagnoses conjunctivitis. Later that evening, the doctor learns that many other children have presented with similar symptoms after appointments with the same ophthalmologist.
Adenovirus
epidemic keratoconjunctivitis
59
A 55-year-old man is hospitalized for a recent onset of high fever, headaches, and sporadic sensations of smelling sausages. Physical exam reveals neck stiffness, prompting the physician to perform a lumbar puncture. CSF values indicate elevated lymphocytes, elevated protein, and normal glucose. A CT image confirms encephalitis localized to the temporal lobes.
A diagnosis is confirmed by PCR of the CSF. The physician begins treatment with acyclovir and informs the patient that he may suffer permanent neurological abnormalities from the infection.
Why would this patient also be at risk of blindness?
HSV 1
-most common cause of sporadic encephalitis in the US
recurrent keratoconjunctivitis is common cause of blindness in the US
60
At a preterm evaluation, a 31-year-old pregnant mother reports pain on urination and a burning, itching sensation in the genital area. A careful exam of her vagina reveals a vesicular rash. The physician confirms a diagnosis with a Tzanck smear of the lesions showing multinucleate giant cells with intranuclear inclusion bodies. The mother is administered acyclovir with assurances that the infection will likely resolve, but she is informed that should the infection persist, her child will have to be delivered by cesarean section.
HSV 2
61
A 72-year-old woman complains to her doctor of a burning, painful rash on her chest. A physical exam reveals fever and
a vesicular, erythematous rash limited to the right side of her chest and overlapping the dermatomal area of T7–T8. The physician confirms a diagnosis by a Tzanck smear of the lesions showing multinucleate giant cells with intranuclear inclusion bodies. The physician administers acyclovir and explains that though the rash will likely ameliorate, the regional pain might persist longer.
How can this virus be transmitted?
WHere does this virus lay dormant when inactive?
If this virus was located on the forehead in the distribution of CN V, what would you be concerned about?
Varicella-Zoster
via resp secretions or by contact with the vesicles themselves
Dorsal root ganglion
Could possibly lead to blindness (Herpes Zoster opthalmicus)
62
A 34-year-old kidney transplant patient currently on immunosuppressants complains of shortness of breath and coughing. Physical exam reveals fever and abnormal lung sounds while chest X-ray indicates interstitial infiltrates in the lungs. No cysts are detected on silver stain of bronchoalveolar lavage fluid, ruling out Pneumocystis jirovecii infection. The doctor makes a diagnosis after viewing a sample of the patient’s lung tissue, which shows abnormal giant cells with “owl’s eye” intranuclear inclusions
What patient groups are susceptible to this agent?
What family?
Had this been a congenital infection, what defects could have been present?
CMV
CMV in transplant patients causes pneumonia
CMV in aids patients causes retinitis
Herpes dsDNA virus
torChes
CMV #1 cause of viral mental retardation in kids
- retinitis
- esophagitis
- colitis
- deafness
63
A 20-year-old female college student reports to the medical center complaining of “the flu.” She reports fever, night sweats, a very painful sore throat, and headaches. She thought she could endure the illness, but she became frustrated after feeling “so sleepy all the time.” Physical exam reveals enlarged lymph nodes and a slight splenomegaly. Results from a blood smear later that day reveal lymphocytosis with about 20% lymphocytes having an abnormally large nucleus and vacuolated cytoplasm. The student is assured that the illness will spontaneously resolve within 2–3 weeks, but that she should avoid contact sports during that time. She is also told not to share drinks to prevent spread of the illness.
What does the monospot test detect?
In AIDS patients, what can this virus cause?
What malignancies is this virus associated with?
EBV
-lymphocytosis with atypical lymphocytes (large, activates T cells that react against B cells)
EBV causes monospot positive mono, meaning that heterophile antibodies are present
In AIDS patients -> can cause oral hairy leukoplakia (cant be scraped off)
Burkitts lymphoma (africa)
Nasopharyngeal carcinoma
64
A physician interested in medical history comes across a narrative recorded in Africa about a group of patients plagued by “vesicles all over their bodies.” The vesicles are described as “oozing” and “viscous,” causing body surfaces to stick together. Even more dramatic, the story describes how the disease started with a few but soon engulfed an entire village. Little more than supportive care could be offered to these patients, most of who soon died.
What category of bioterrorist agents would this be classified under? Why is there so much concern over the use of this virus as a biochemical weapon?
Smallpox (poxviridae DNA virus family)
Category A
No effective treatment, and there have not been any smallpox vaccinations done since the 1970's so if aerosolized could potentially cause massive problems
65
A 23 year old HIV positive male goes to his local health clinic for “bumps in his pubic region.” On examination, the physician notes flesh-colored, pearly nodes with central craters. She recommends that he cover the lesions to prevent scratching and spread. What agent, what family?
Molluscum Contagiosum
poxviridae, replicates in the cytoplasm
66
The star high school football player of a small town presents to the local clinic with itchiness between his toes, as well as itchi- ness and pustules on his index and middle fingers. Skin scrapings from the patient’s feet reveal branched hyphae. However, analysis of the pustular fluid shows no such organisms. The nurse prescribes topical ointment to be applied to the toes, and within a few weeks, both the toe and finger itchiness resolve.
Tinea infections caused by Microsporum, Trichophyton, Epidermophyton
67
A man presents with small raised ulcerations extending proximally from his left index finger. The physician learns that the patient enjoys gardening as a hobby. Upon further questioning, the patient reports that he only started using gloves 3 months ago, following a painful thorn prick received while weeding his rose garden. The doctor cultures a nodule specimen and notices organisms shaped differently at different temperatures. Oral potassium iodide is considered as a treatment. Lepromin skin test is definitely not positive.
What will be seen on microscopic examination at 25 degrees? 37 degrees? How is this characterized?
Sporothrix Schenkii
at 25 there will be branched hyphae
at 37 there will be yeast
68
An old man and his great grandson visit Death Valley National Park in the deserts of Southern California. Upon returning from their visit, the man develops breathing difficulties along with arthralgias, periarticular swellings, and erythema nodosum. X-rays reveal a pneumonic infiltrate as well as granulomas. A diagnosis is confirmed by observing spherules containing individual endospores in tissue specimens. As expected, the child remains unaffected but several weeks later tests positive for a fungal antigen DTH reaction.
What would these appear as under various temperature conditions?
How would you prepare this for culture?
Where is this typically found? Who is at greatest risk of infection?
Coccidioidomycosis
Inhaled as an endospore
branched hyphae at 25°C
single cells at 37°C
silver stain and sabourads agar
SOuthwest CA, Arizona
immunocompromised (AIDS)
69
An elderly cave explorer in Ohio complains to his physician of weakness in the last few months. A physical exam reveals sores in his mouth, and X-ray shows small calcifications throughout the body. A lung biopsy reveals small budding cells within macrophages. Based on his age, location, and biopsy results, the physician begins the patient on oral amphotericin B.
How would you prepare this organism for examination/culture?
Where is this organism typically found in?
What is the characteristic giveaway in this question stem for this organism?
Histoplasma encapsulatum
Silver stain and sabourads agar
branched hyphae at 25°C single cells at 37°C
Found in bird and bat shit in Mississippi valley -> endospores inhaled -> survives in Macrophages
In Histoplasmosis, the pneumonic lesions calcify
70
A man from Missouri develops weakness and night sweats. His physician notes sores on the patient’s skin. Biopsy of the skin lesions reveals a large, thick walled, budding yeast. The doctor informs the patient of his rare yet serious diagnosis and begins a course of antifungals, including amphotericin B. Besides the seriousness and rareness of this disorder, what are the key characteristics to note in the question stem?
Where is this usually found?
Blastomyces Dermatitidis
keys are thick walled, budding yeast and the skin ulcers. Skin ulcers not seen in the other systemic fungal infections
Found in MIssissippi River Valley and can extend north, found in rotting soil and wood
branched hyphae at 25°C single cells at 37°C
tissue biopsy: large budding yeast
Blastomycosis is the rarest yet most severe of the systemic fungal infections.
71
Several months ago, a patient presented to a free clinic with a thick, white membrane covering the roof of his mouth. After a thorough social history, the doctor suspected a possible HIV infection. However, at the time, the patient refused testing and never returned for follow-ups. Now, the patient revisits the clinic complaining of painful swallowing and severe chest pains. The doctor immediately places the patient on fluconazole and makes arrangements for future treatments and tests.
What does blood assay screening for this organism detect?
What will be seen on morphologic exam on this organism?
In immunocompetent patients, what does this organism typically cause?
Candida Albicans
Beta-D-lactam levels in blood assay
pseudohyphae and yeast
Immunocompetent patients:
- thrush
- vaginitis(cottage cheese)
- diaper rash in infants
if there is esophageal candidiasis or disseminated candidiasis, think immunocompromise
72
An amateur bird keeper presents with headache and a stiff neck. Fearing some form of meningitis, the EW physician orders a CT scan. The image reveals well-circumscribed ringlike lesions in the brain. Subsequent CSF analysis from a lumbar puncture shows ↑ CSF pressure, ↑ protein, ↓ glucose, and encapsulated budding yeast with India ink stain. The patient is administered amphotericin B and flucytosine.
A specific antigen test is performed for a more accurate diagnosis, what is this particular antigen test detecting?
Cryptococcus Neoformans
Detects the polysaccharide capsule of the cryptococcus fungi
73
Patient presents with violet lesions on their forearm following a wound he suffered while stacking rotting firewood. He begins developing multiple clusters of these lesions. What is causing this?
After a sample and preparation with KOH, what would you expect to see?
Chromoblastomycosis caused by Cladosporidium and Phialophora
After KOH prep you would see copper-colored sclerotic bodies
74
A homeless man arrives at the EW complaining of difficulty in breathing. His medical history is not obtainable, but the man does report increasing fatigue and weight loss over the past few months. Physical exam reveals lymphadenopathy, tachypnea, and bilateral rales in the lung bases. Chest X-ray shows diffuse infiltrates bilaterally. The doctor decides to perform a bronchial lavage and, with silver stain, reveals numerous cysts containing several dark oval bodies. The doctor begins the patient on TMP-SMX and orders an HIV and blood test.
When did this patient likely become infected with the causative agent?
Assuming he is HIV positive, what is his likely CD4 count?
PCP
likely was infected in childhood and the fungi layed dormant until he became immunocompromised
Likely below 200
75
A woman undergoing chemotherapy for acute myeloid leukemia alarms her physician when she develops a fever, experiences chest pains, and coughs up blood. Chest X-ray shows pulmonary infiltrates, and subsequent biopsy reveals branched hyphae. The physician is quite concerned with the diagnosis and begins treating the patient with antifungals including amphotericin B.
Aspergillosis
key words are branched hyphae and bloody cough (ass w/ aspergilloma)
76
After a camping trip to Mexico, a patient visits her doctor complaining of loose stools and abdominal cramps. The patient describes the stools as having flecks of blood and lots of mucus. The doctor orders a stool specimen in which she finds motile amoeba with ingested RBCs. She starts the patient on metronidazole and considers a CT scan to detect any liver abscesses. Who is most at risk of transmitting this disease?
What are the different types of diarrhea caused by protozoa?
Entamoeba Histolytica
homosexual men
bloody → Entamoeba histolytica
fatty → Giardia lamblia
watery →
Cryptosporidium parvum
77
A student cuts short an extended backpacking trip in Yosemite Park after developing diarrhea. He explains to his doctor that the diarrhea is nonbloody but smells very bad. On further questioning, the student tells his doctor that he has been drinking water from a fresh water spring. The patient appears malnourished on physical exam. A diarrhea sample reveals 2-nuclei motile amoeba with a tear-drop shape and 4 pairs of flagella. The student is given metronidazole.
Giardia Lamblia
78
An HIV patient becomes alarmed after developing a persistent diarrhea. He tells his physician that the diarrhea is watery and without blood. Upon learning that the patient visited a vacation farm before the diarrhea started, the doctor orders an acid-fast stain of the patient’s stool sample.
Cryptosporidium
79
A teenage girl complains of vaginal itching and burning. Sexual history reveals numerous sexual partners. Her gynecologist performs a pelvic exam and finds a greenish, foul-smelling thin discharge from the vagina. A wet mount of the discharge reveals motile amoeba, each with 1 nucleus and 5 flagella. The patient is started on metronidazole.
Trichomonas Vaginalis
80
An AIDS patient is brought to the EW after suffering a grand mal seizure. The man informs the EW physician that he has suffered a persistent headache in the past few weeks but denies any sensory problems or weakness. Fearing a brain tumor, the EW physician orders a CT scan of the patient. However, the scan, instead, reveals several ring-enhancing masses in the patient’s brain. The physician confirms his suspicions when he learns the patient has many cats at home. He expects that a brain biopsy would show crescent-shaped trophozoites.
What would an eye exam likely show?
Had this been a congenital infection, what defects could result?
Toxoplasma Gondii
-can cause chorioretinitis
This is the T in TORCH
can cause retinitis, microcephaly, retardation, blindness, mental retardation
can also cause a chorioretinitis later in life as a result of congenital infection
81
A recent immigrant from a tropical country presents with weight loss and fever. A physical exam reveals massive hepatosplenomegaly with associated edema, as well as hyperpigmented skin patches. The doctor orders a CBC and spleen biopsy. CBC reveals thrombocytopenia, anemia, and leukopenia, while spleen biopsy shows macrophages containing protozoa. The doctor begins the patient on an antimony compound.
Leishmania Donovani -> visceral leishmaniasis
82
A Mexican man complains to his doctor of worsening constipation and stomach pains. On physical exam, the doctor is sur- prised to find an enlarged heart on auscultation and moderate arrhythmia. Following an abdominal X-ray revealing megacolon, the doctor makes his diagnosis. Unfortunately, the treatments she offers are only symptomatic.
Chagas, T. Cruzi
83
An East African man is asked to leave his job after repeatedly falling asleep. He visits the doctor hoping to cure his somnolence, as well as accompanying headache and dizziness. During the interview, the patient explains that he had suffered recurring bouts of fever and enlarged lymph nodes before the sleepiness started. The doctor decides to perform a lumbar puncture, and after finding a flagellated protozoan in the CSF, he plans to start the patient on melarsoprol.
What is the vector for this disease? Which subtypes are faster/slower?
What causes the relapsing fevers?
Trypanosoma brucei
vector is tsetse fly
Rhodiense (east) -> RAPID
Gambiense (west) -> gradual, slower onset
Variable surface glycoprotein (VSG)
-similar to the vmp lipoprotein antigenic variation in Borellia Recurrentis
84
student reports to his college clinic complaining of “the flu.” He explains that he has been suffering from intermittent headaches, fever, and muscle aches. Assuming the flu, the physician sends the student home with acetaminophen. Now, days later, the student returns to the clinic EW with chills, extreme fever, and debilitating fatigue. Physical exam also reveals yellow sclera and severe splenomegaly. CBC reveals low hematocrit, and urinalysis shows hemoglobinuria. Alarmed, the EW doctor questions the student about recent travels and learns that he has just returned from a visit to India. A blood smear showing ring shapes confirms the diagnosis, and the patient is begun on mefloquine.
Plasmodium sp.
85
A man in Louisiana develops coughing, fever, and abdominal pain. His doctor orders a series of X-rays that show pulmonary infiltrates characteristic of pneumonia, as well as intestinal images consistent with obstruction. On CBC, the patient has increased eosinophils. The doctor examines a stool sample from the patient and discovers microscopic oval eggs with rough surfaces. The doctor makes a diagnosis, administers pyrantel pamoate, and forewarns the patient to expect worms in his stool.
Ascaris lumbricoides
86
A mother brings her child to a developmental specialist. She is concerned because of what she considers “negative” behavior. When asked to elaborate, she explains that her child scratches his anal region continuously, even in public places. Indeed, even his kindergarten teacher mentioned it in the last parent–teacher meeting. Before pursuing psychological studies, the specialist recommends a “Scotch tape” test based on past cases with similar complaints.
Enterobius Vermicularis
87
A cow rancher arrives at the EW terrified after discovering a wormlike structure protruding from his anus. After reassuring the man and taking a proper history and physical, the doctor examines a stool sample. As expected, the doctor finds rectangular proglottid segments with the naked eye and uses a low-power microscope to detect eggs. The doctor prescribes niclosamide and a cathartic, confident that the patient will be cured with a single dose. The doctor also instructs the patient to avoid poorly cooked beef in the future.
Taenia Saginata
88
A Vietnamese immigrant of 10 years presents with severe headaches and seizures. A physical exam reveals several nodules across her body. Concerned about a neurologic disease, the doctor first orders a head CT scan that shows five calcified cysts. This observation, along with high eosinophils on a CBC, prompts the doctor to perform a biopsy of a nodule. A diagnosis is made after the doctor finds cysts in the nodule, and the patient is begun immediately on praziquantel and steroids.
Taenia Solium
89
A pig farmer visits his doctor with muscle aches, fever, and periorbital and facial edema. These symptoms were preceded 2 weeks earlier by an upset stomach and diarrhea. Blood labs show eosinophilia, ↑ IgE, and muscle enzymes. Because the symptoms are not severe, the doctor opts not to perform a muscle biopsy; however, if she had performed the biopsy, she would have expected to find cysts.
Trichenella Spiralis
90
A woman presents with abdominal discomfort. The discomfort begins as a mild sensation in the RUQ but has become progres- sively more painful. Physical exam reveals hepatomegaly. The doctor decides to perform an abdominal CT, which shows a large circular mass in the liver with multiple daughter cysts encapsulated by “eggshell” calcifications. Serology, but not stool samples, is used to make a diagnosis. The doctor elects to surgically remove the mass but first neutralizes the cyst contents by injecting ethanol. What is this disease also known as?
Echinococcus granulosus
Hytadid cyst disease -> cause allergic reaction if these cysts rupture
91
A South Carolina woman visits her doctor after developing diarrhea. The doctor performs a blood test and finds elevated eosinophils. Suspecting a parasite infection, the doctor examines a stool specimen. After finding larvae without eggs, the doctor solidifies a diagnosis upon learning that the patient frequently walks around her house barefoot. The patient is started on thiabendazole to cure the symptoms as well as to prevent complications such as peritonitis.
Strongyloides stercoralis
92
A child from a small Alabama community presents with severe weakness and pallor. A CBC shows reduced hematocrit with hypochromic microcytic RBCs as well as increased eosinophils. To investigate the possibility of parasites, the physician orders a stool sample in which she finds numerous eggs. The physician prescribes mebendazole and iron tablets and explains that the child may have acquired the illness by walking barefoot. What are the various names for this organism?
Necator Americanus - hookworm
93
An African man comes to the EW after vomiting blood. He also reports that his stools have been dark for the last few years. In the history, the patient denies alcohol use and states that freshwater fishing is a hobby. Endoscopy shows esophageal varices, and stool specimens contain eggs. The patient is started on praziquantel.
An African woman visits her doctor after urinating blood. In her history, she states that she worked in freshwater rice fields before coming to the U.S. Cytoscopic examination of the bladder shows inflammatory lesions, and urinalysis demonstrates eggs. Imaging reveals hydronephrosis of the right kidney and a mass extending from the right ureter into the bladder. She is started on praziquantel.
Schistosoma sp.
-can invade the intestinal wall and lead to polyps, melena
Schistosoma haematobium, ass w/ bladder squamous carcinoma
94
A traveling physician visits a remote riverside village in a South American country and discovers that most of the older village inhabitants are blind. On physical exam of some of the members, she notes skin nodules and hyperpigmented rashes. To prevent other village members from becoming blind, she administers donated ivermectin to many people in the village and urges mosquito control.
Oncocherca Volvulus
95
A patient from a tropical village has an enormously swollen scrotum and lower extremity. The skin around the swelling has become scaly and thick. The patient remembers feeling enlarged nodes in the groin months before the swelling began, but because of poor health resources in the area, he never saw a physician. Samples of his blood drawn at night show wormlike organisms under a microscope. A visiting doctor strongly recommends that the patient and other villagers sleep with a mosquito net to prevent more infections.
Wuchereria bancrofti
