Immuno
Bacteria 1
Bacteria 2
Everything else 1
Everything else 2
100

A bacterial pathogen is introduced into the bloodstream through an infected central line. What immune cell recognizes the bacteria, digests it within a phagolysosome, and combines its peptides with a type 2 major histocompatibility complex (MHC)?

Macrophages/Dendritic cells

100

A 50-year-old industrial worker engaged in handling animal products develops a painless papule on his right forearm where he had a minor abrasion 5 days earlier. The papule became a vesicle after 48 hours and ruptured, leaving an ulcer with a black necrotic area in the center and surrounding edema. What bacteria? Name its toxins.

Bacillus Anthracis. Protective antigen, lethal toxin, edema toxin

100

A 20-year-old male college student presents with fever, chills, malaise, headache, photophobia, confusion, and numerous petechiae on his extremities and trunk. Patient reports having a stiff neck. Gram staining of the CSF reveals Gram-negative cocci in pairs. Name bacteria and a complication.

Neisseria Meningiditis. Shock, DIC, Waterhouse-Friderichsen syndrome

100

Within 48 hours of consumption of raw oysters from a restaurant in North Carolina, 3 men in their 30s developed diarrhea and severe vomiting accompanied by headache, low-grade fever, and chills. They recovered with administration of intravenous fluid. In a week's time, all other adults and children in their households became sick with similar symptoms. A viral agent was considered as the cause of this outbreak of gastroenteritis.

Vibrio Vulnificus

100

A 3-year-old boy is evaluated for a 24-hour history of diarrhea. His mother reports that he had five episodes of foul-smelling watery diarrhea associated with decreased appetite. A few other children at the same daycare center have presented with the same problem. On physical examination, the child is well hydrated and his abdomen is tender. What is on your differential?

Giardia

200

A 60-year-old man presents with a deep puncture wound on his foot. His clinical history indicates that he has recently emigrated from Peru and does not recall receiving any immunizations in childhood. Horse antibodies against tetanus are administered to him; a few days later, he develops chills, rash, and arthritis, which are caused by a small immune complex deposition in tissues. What type of hypersensitivity reaction is this?

Type III

200

A 42-year-old previously healthy woman comes to the office due to weakness and difficulty walking. She states she had cramping abdominal pain and diarrhea 2 weeks ago after an outdoor picnic, which spontaneously resolved after 3 days. She has had no fever, headache, neck pain, or bowel or bladder dysfunction. Vital signs are within normal limits. Bilateral lower-extremity weakness with loss of deep tendon reflexes is present. Bilateral upper-extremity muscle strength, reflexes, and coordination are normal. Sensation to touch and pinprick is normal throughout. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of this patient's current condition?

Guillain Barre. Campylobacter

200

A 45-year-old woman is brought to the ED via ambulance; she is accompanied by her very anxious husband. He reports that she has been vomiting for several hours, and she has complained of acute abdominal pain and blurred vision after eating home-canned green beans. Examination reveals dilated pupils, diplopia, acute paralysis of the upper limbs, and respiratory distress. What bacteria?

Clostridium Botulinum

200

A 56-year-old man was admitted to a hospital in central Illinois with symptoms of high fever, chills, dry cough, headache, night sweats, and chest pain of 7 days duration. He has been experiencing shortness of breath since the previous day. With his 3 sons, he was engaged in the repair work of an attic of an old building and had cleaned the accumulation of bird and bat droppings in the attic. What are we worried about?

Histoplasma

200

A 40-year-old resident of the US was brought to the urgent care center with a 4-day history of fever, chills, headache, sweating, and prostration. 2 weeks ago he had returned from a trip to Haiti. Blood films stained by Giemsa were positive for parasites. Erythrocytes in the blood film appeared normal in size and intraerythocytic delicate ring forms and crescent shaped gametocytes were seen. Some of the ring forms had double chromatin and multiple rings were observed in some RBCs. What is the parasite?

Plasmodium Falciparum

300

A 17-year-old boy is brought to the emergency department because of recurrent episodes of swelling of his lips and hands over the past year. Today, he also complains of abdominal pain and nausea. He denies urticaria, pruritus, or any known food allergies. His father had similar episodes during adolescence. Physical examination shows nonpitting, nonpruritic swelling of the lips and tongue without erythema or rash. Lab studies show low C4 levels. What enzyme is deficient?

C1 esterase inhibitor (hereditary angioedema)

300

A 45-year-old woman presents with a 2-day history of abdominal cramps and bloody diarrhea. She has just returned from her vacation in India, where she ate many of the local foods. Her blood pressure is 120/80 mmHg, pulse rate is 84/minute, and temperature is 37.8°C. What is on our differential?

Shigella Dysenteriae

300

A previously healthy 24-year-old woman presented with high fever of sudden onset, severe myalgia, headache, vomiting, diarrhea, and diffuse rash resembling sunburn. She was on the 4th day of her menses and was using tampons. Her blood pressure was noted as 70/40. As part of laboratory investigations, blood, urine, and vaginal cultures were done. Name bacteria, toxin

Staph aureus. Toxic shock syndrome toxin 1.

300

A 45-year-old woman presents with a 1-month history of headache with low-grade intermittent fever accompanied by nausea, vomiting, and altered mental status. Her previous medical history was significant for lupus erythematosis diagnosed 5 years ago, for which she was receiving chronic steroid therapy. On examination, the patient appears confused; her temperature is 39°C and she has neck stiffness. What infection are we worried about and how can we diagnose it?

Cryptococcus, spinal tap and India ink smear

300

A 32-year-old office worker at the Venezuelan embassy was admitted to The George Washington University Hospital following a grand mal seizure. During his youth he had experienced seizures that included numbness of the upper left extremity, unconsciousness, and residual left-side headaches. He had not experienced such symptoms for many years until they resurfaced several months ago when he recalled similar progressive weakness, sharp pain in his upper left arm, blurred vision, and motor disturbances. An encephalogram revealed calcification in the third ventricle. What is this disease and it is caused by which parasite?

Neurocysticercosis. Taenia Solium

400

A 26-year-old woman presents with a 3-day history of right knee pain; her knee is red, hot, and swollen. In addition, she reports a skin rash and mild pain in her wrists that has been present for the past 2 days. Temperature is 101.6° F, BP is 130/80 mm Hg, P is 98/min, and RR is 12/min. She is sexually active with 2 different partners. Physical exam reveals an erythematous, swollen, tender right knee joint, and bilateral pustules on her wrists. She states that she has a history of recurrent bouts of infections. A preliminary diagnosis of septic arthritis is made. The clinician suspects that the patient has some type of immunodeficiency. What complement deficiency is most likely associated with the dissemination of the causative agent in this patient?

C5b - C9

400

A 12-year-old boy presents with an elevated body temperature of 39.9°C. He has a history of fishing and playing in the woods with his dog in areas of high grass. Other than his current illness, there is nothing remarkable in his medical history. Physical examination reveals an acutely ill child with a notable macular rash on his lower extremities and palms. The patient had experienced severe joint pain and intermittent bouts of diarrhea. What are we suspecting?

Rickettsia rickettsii

400

A 43-year-old man presents to the emergency department with progressive difficulty walking and urinary incontinence over the past year. He also reports episodes of sharp, shooting pain in his legs and poor balance in the dark. He has not seen a physician in years. Physical examination shows pupils that constrict with accommodation but not with light, absent ankle reflexes, and a wide-based gait. What are these symptoms called and what is the disease (be specific)?

Argyll Robertson pupils and tabes dorsalis, tertiary syphilis / neurosyphilis

400

A 2-year-old boy is brought to the clinic with profuse watery diarrhea and vomiting for 3 days. He attends daycare, and several other children recently developed similar symptoms. Physical examination shows signs of dehydration. Stool studies are negative for leukocytes and occult blood. The physician suspects a certain virus infection. This virus infects and damages mature enterocytes at the tips of small intestinal villi, leading to villous atrophy and malabsorptive diarrhea.
What is the virus and through what cells does the virus access the underlying lymphoid tissue of the ileum? 

Rotavirus, M cells

400

A 24-year-old tall, thin man comes to the emergency department after suddenly developing sharp left-sided chest pain and shortness of breath while playing basketball. He has no history of trauma or prior illness. Physical examination reveals hyperresonance to percussion, and markedly diminished breath sounds over the left upper chest. 

What procedure would you use to treat this, and BE SPECIFIC about where you would go to avoid damaging important structures?

Chest tube, 5th or 6th intercostal space in the midaxillary line, INFERIOR aspect of selected intercostal space (along upper border of rib), tube directed UP to drain air

500

A 32-year-old man presents to the clinic with complaints of dark urine in the morning and increasing fatigue over the past several months. He denies dysuria, flank pain, or recent infections. His past medical history is unremarkable. Physical examination shows mild pallor and no jaundice or splenomegaly. Laboratory studies reveal anemia. Urinalysis shows hemoglobin but no RBCs. What would flow cytometry demonstrate?

Absence of CD55 and CD59 on RBCs (paroxysmal nocturnal hemoglobinuria)

500

What is this classic finding on blood smear called and what infection does it indicate?

Morulae - ehrlichiosis

500

What is this finding called? What is it made of (be specific) and what infection is it associated with?

Langhans giant cell = fused macrophages oriented around tuberculous antigen with the multiple nuclei oriented in a peripheral position

500

A 7-year-old boy is evaluated for recurrent viral and fungal infections. He has no history of recurrent bacterial infections. Physical examination reveals a small mandible, low-set ears, and widely spaced eyes. Laboratory studies show hypocalcemia and absolutely decreased T cells. A biopsy of a normal thymus (from another patient) is examined to compare normal architecture. What is this structure called, where in the organ is it found, and what is it made of (be specific)?

Hassall's corpuscle, medulla, epithelioreticular cells

500

Name the muscle, and trace its innervation starting at a horn of the spinal cord (BE SPECIFIC).

Longissimus. Ventral (anterior) horn --> ventral (anterior) root --> spinal nerve --> posterior ramus

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