Opportunistic Infections (Buxton)

Question 1

What are 3 things that can compromise a host?

Answer 1

Defects/injury to physical barriers

Deficiencies in innate immunity

Deficiencies in adaptive immunity

Question 2

A 12 year old child is severely burned in a house fire. He was hospitalized for over a month with 3rd degree burns on his leg. About a week after admission, he developed an infection of the burned areas. Blue-green pus was associated with the infection.

What factors increased this child’s risk of infection?

Answer 2

Burn - loss of protective skin barrier; severe burns lead to decrease in neutrophil function

Hospitalization - at risk for nocosomial infections

Question 3

A 12 year old child is severely burned in a house fire. He was hospitalized for over a month with 3rd degree burns on his leg. About a week after admission, he developed an infection of the burned areas. Blue-green pus was associated with the infection.

Which organisms are the most common causes of burn infections?

Answer 3

Pseudomonas aeruginosa (wet areas)

Staphylococcus aureus (skin)

Staphylococcus epidermidis (skin)

Streptococcus pyogenes (skin, mucous membranes)

Candida (skin, mucous membranes)

Aspergillus (soil, dark & damp areas - spores)

*burn infections often polymicrobial*

Question 4

Answer 4

Pseudomonas on nutrient agar

Question 5

Answer 5

Aspergillus

Question 6

Name the following microbes isolated from the 12 y/o burn patient’s blood and/or exudate.

1. Gram (+) cocci, catalase (+), coagulase (-)
2. Gram (+) cocci, catalase (+), coagulase (+)
3. Gram (-) rod, greenish colored colonies on nutrient agar
4. fungus in below image

Answer 6

1. Staph epidermidis
2. Staph aureus
3. Pseudomonas
4. Aspergillus

Question 7

Of the 4 microbes isolated from the 12 y/o burn patient’s wounds, what was isolated from his burn? What was isolated from his blood?

Answer 7

Burn - Pseudomonas, Staph epidermidis

Blood - Pseudomonas, Staph aureus, Aspergillus

Question 8

How did the 12 y/o burn patient become infected?

Answer 8

Skin colonization - Staph

Hospital environment - Pseudomonas, Aspergillus

Question 9

Describe the pathogenesis of burn wound infections.

Answer 9

Bacteria that colonize skin are first to invade wound (within days). Pseudomonal & fungal infections occur ~1 week after hospitalization. Important virulence factors include resistance to phagocytosis & enzymes that facilitate invasion.

Question 10

Describe the epidemiology of Pseudomonas.

Answer 10

Ubiquitous

Resistant to some common disinfectants

Antibiotic resistance is common

Causes infections in CF, catheterized, burn, and intubated patients

Question 11

What are common locations for Pseudomonas infections?

Answer 11

Skin & musculocutaneous tissues

Respiratory tract

CNS

Localized

Blood (bacteremia)

Heart (endocarditis)

Urinary tract (UTI)

Question 12

Answer 12

Ecthyma gangrenosum - consequence of Pseudomonas septisemia; hemorrhagic necrosis of the skin

Question 13

How would you treat your 12 y/o burn patient who is positive for Staph epidermidis, Staph aureus, and Aspergillus?

Answer 13

MRSA - Vancomycin, Linezolid, Streptogramin

MSSA - Vafcillin/Oxacillin/Dicloxacillin, 1st/2nd gen. cephalosporin, Clindamycin

Pseudomonas - Extend spectrum penicillin + beta-lactamase inhibitor, carbapemen, Monobactam, fluoroquinolones, Ceftazidime, Cefepime, aminoglycosides

Aspergillus - Voriconazole, Caspfungin

So…Vancomycin + Amp B until data comes back

Question 14

A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.

Why is an infant considered immune compromised?

Answer 14

Decreased: production of neutrophils, killing by phagocytes, complement levels, NK cell activity, in vitro lymphocyte proliferation, cytokine production by lymphocytes, CTL responses, expression of CD40L, production of Ig (especially IgG & IgA).

Question 15

A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.

How did the infant become infected?

Answer 15

Fetal infection can occur from:

transplacental transmission

ascending infection through ruptured amniotic membranes

during birth through an infected birth canal

Question 16

A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.

What were the symptoms, if any, in the mother?

Answer 16

Nausea, vomiting, diarrhea, fever, malaise, back pain, and headache

Many pregnant women can carry Listeria asymptomatically in their GI tract or vagina

Maternal infection with Listeria can affect pregnancy by causing chorioamnionitis, premature labor, spontaneous abortion, or stillbirth

Question 17

A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.

Where is the organism found in nature - how did the mother become infected?

Answer 17

Widely distributed in nature - intestinal tracts of many mammals; most commonly associated with ingestion of prepared meat, dairy products, unwashed raw vegetables, and seafood. Soft cheeses and unpasteurized milk have bee nthe most frequently incriminated dairy products.

Question 18

A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.

How would you treat the baby?

Answer 18

Ampicillin + Gentamicin

Question 19

A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.

What made this patient susceptible to this infection?

Answer 19

Corticosteroids - long-term use

Question 20

A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.

What is the source of the bacteria?

Answer 20

Ubiquitous in soil and water

Question 21

A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.

What are the unusual features of this bacteria?

Answer 21

Cell walls contain mycolic acid, thus pick up acid fast stain

Question 22

A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.

How should she be treated?

Answer 22

TMP/SMX is drug of choice; other antibiotic combinations can be used

Question 23

Answer 23

Nocardia

Question 24

A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.

If patient has pulmonary nocardosis, what symptoms would you expect to find?

Answer 24

Lobar pneumonia with abscess formation

May mimic TB clinically - fever, weight loss, chest pain

Infection can spread from lung to other sites via blood

Question 25

A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex. What are the diagnostic features of this organism?

Answer 25

Group of related organisms - MAC Bacilli-weakly gram (+), strongly acid fast

Question 26

Answer 26

MAC infection in aids patient - disseminated acid fast rods in tissue

Question 27

A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex. What are the sources of this organism?

Answer 27

Infect many bird & mammal species Ubiquitous - in water & soil Infection thought to occur by ingestion or inhalation

Question 28

Describe the pathogenesis of disseminated MAC infection.

Answer 28

Enters immunocompromised person via ingestion/inhalation - infects resting macrophages of mucosal epithelium - carries organism throughout body (lymphatic sites) - replicates to very high numbers within macrophages within various tissues - infected macrophages secrete cytokines - cytokine storm

Question 29

A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex. What diseases does it cause in immune-competent individuals?

Answer 29

Pulmonary disease in persons with underlying lung conditions, smokers

Question 30

A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex. How is it treated?

Answer 30

In AIDS patients: Clarithromycin/Azithromycin + Ethambutol

Question 31

A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex. Could the infection have been prevented in this patient?

Answer 31

AIDS: yes - prophylaxis with Clarithromycin or Azithromycin when CD4 count falls \< 50/cmm

Question 32

A 42-year old male with AIDS develops neurologic signs. What are some infectious causes of neurologic signs in AIDS patients?

Answer 32

AIDS dementia complex (ADC) Cryptococcal meningitis Toxoplasma gondii encephalitis Progressive multifocal leukoencephalopathy (JCV)

Question 33

A 42-year old male with AIDS develops neurologic signs. The patient was brought to his physician’s office by a friend who reports progressive confusion developing over the past 6 weeks. The patient has become increasingly forgetful. Over the past week, he has developed progressive weakness on the right side of his body (Hemiparesis). CSF exam was normal. PCR of CSF found DNA of JC virus. What does this patient have in addition to JCV? What symptom(s) clues you in to this diagnosis? What other symptoms might the patient exhibit?

Answer 33

PML - progressive multifocal leukoencephalopathy - hemiparesis Insidious onset of focal symptoms including behavioral, speech, cognitive, moor, and visual impairment due to focal areas of demyelination throughout the brain.

Question 34

What virus causes a common latent infection, has a seroprevalence rate among adults \> 90%, is not associated with disease in healthy people, and causes PML in profoundly T cell suppressed individuals?

Answer 34

JC Virus

Question 35

A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. What is the most likely diagnosis?

Answer 35

Cryptococcus neoformans

Question 36

Answer 36

Yeast on India ink stain

Question 37

A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. Where is this organism found in nature?

Answer 37

Associated with dried pigeon droppings

Question 38

A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. How did he become infected?

Answer 38

Enters through inhalation, evades phagocytosis and Th1 cell responses, enters blood, disseminates to meninges and other tissues

Question 39

A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. What are important virulence factors of this organism?

Answer 39

Produces a thick polysaccharide capsule once inhaled

Question 40

A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. How is this infection diagnosed?

Answer 40

Detection of capsular polysaccharide antigen in serum or CSF, confirmed with growth on Sabouraud's agar or Heart Brain infusion agar.

Question 41

A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. What is the treatment?

Answer 41

Amphotericin B + Flucytosine Maintenance with Fluconazole until CD4 cells increase \> 100 for \> 6 months

Question 42

An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks. What was the source of this infection?

Answer 42

Endemic mycosis Found in Ohio, Missouri, and Mississippi River Valleys Found in soil contaminated with bird and bat droppings

Question 43

An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks. Describe the pathogenesis of disseminated histoplasmosis.

Answer 43

Most likely the result of a prior infection Fungi once contained in lung granulomas were able to replicate and disseminate following immune suppression Spreads throughout body Can be isolated from many tissues Fatal if not treated

Question 44

An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks. Who is at risk for disseminated histoplasmosis?

Answer 44

Patients with profound T cell immune suppression

Question 45

An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks. What other clinical manifestations are caused by H. capsulatum?

Answer 45

Initial infection in healthy person - flu-like illness Chronic pulmonary histoplasmosis (patients with underlying pulmonary disease) - organism does not get walled off effectively, which can lead to cavitations and hemoptosis

Question 46

An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks. How should patient be treated?

Answer 46

If overwhelming, disseminated - Amphotericin B with maintainance with Itraconazole until/if sustained improvement in CD4 numbers and viral load

Question 47

Answer 47

Musculocutaneous ulcers in the mouth; skin lesion due to Histoplasma

Question 48

A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts. With what is he infected?

Answer 48

Pneumocystis jiroveci

Question 49

A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.

Answer 49

Pneumocystis jiroveci

Question 50

A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts. What kind of organism is this?

Answer 50

Fungus

Question 51

A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts. What is the source of the organism?

Answer 51

Source has not been definitively identified. May be acquired by inhalation of airborne cysts Most individuals acquire the organism early in childhood

Question 52

A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts. Describe the pathogenesis of this organism.

Answer 52

Pneumocystis jiroveci Extracellular pathogen controlled by pphagocytic macrophages - enters lung of T cell immune-suppressed individuals - replicates in surfactant - damages basement membrane during proliferation, altering permeability & reducing O2 exchange

Question 53

A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts. How can he be treated?

Answer 53

Pneumocystis jiroveci TMP/SMX for treatment and maintenance

Question 54

A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts. Could this infection have been prevented?

Answer 54

Pneumocystis jiroveci Yes - prophylactice treatment with TMP/SMX with CD4 count falls below 200/ul.

Question 55

A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. What is a localizing sign and why are they lacking in his case?

Answer 55

They're due to inflammatory responses. he has very low neutrophils, thus has poor acute inflammatory responses.

Question 56

A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. What are the causes of fever in a neutropenic cancer patient?

Answer 56

Cancer Cancer chemotherapy

Question 57

A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. What are possible causes for infection?

Answer 57

Neutropenia \< 7 days - Staph, Strep, Pseudomonas, E. coli, Klebsiella Neutropenia \> 10 days - bacterial & fungal - Aspergillus, Candida

Question 58

A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. The boy was hospitalized. Blood and urine cultures were taken and the patient was started empirically on broad spectrum IV antibiotics. What would you recommend?

Answer 58

Broad spectrum antibiotic - Ceftazidime or Cefepime; Carbapenem if extended-spectrum beta-lactamase-producing organisms are a problem in the area Anti-fungal - Caspofungin

Question 59

A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. The boy was hospitalized. Blood and urine cultures were taken and the patient was started empirically on broad spectrum IV antibiotics. Candida albicans was isolated on Sabourauds agar from the boy’s blood. What kind of organism is this, and how did he become infected?

Answer 59

Opportunistic yeast Found as commensals on skin & mucous membranes Causes infection due to: T cell immune suppression, antibiotic therapy, anticancer therapy, neutropenia

Question 60

What are some disease associations of Candida?

Answer 60

Thrush Vaginal yeast infections Esophagitis Candidemia Hepatosplenic candidiasis

Question 61

What are treatment options for candidemia?

Answer 61

Echinocandins (caspofungin) Fluconazole Voriconazole Amphotericin B

Question 62

A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients?

Answer 62

CNS lymphoma AIDS dementia complex Cryptococcal meningitis Toxoplasma gondii encephalitis Progressive multifocal leukoencephalitis CMV encephalitis

Question 63

A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. What are these lesions associated with?

Answer 63

Lymphoma Toxoplasmosis Cryptococcosis

Question 64

A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. After 3 days of hospitalization, the patient died. An autopsy revealed the following: Grossly, the brain was edematous and showed areas of hemorrhagic necrosis. Microscopic examination of brain tissue revealed areas of necrosis and tissue cysts. Can this infection be treated?

Answer 64

Treatment - 3 drug combination Pyrimethamine Sulfadiazine Leukovorin If intolerant of sulfa drugs, prescribe Clindamycin alongside Pyrimethamine

Question 65

A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. After 3 days of hospitalization, the patient died. An autopsy revealed the following: Grossly, the brain was edematous and showed areas of hemorrhagic necrosis. Microscopic examination of brain tissue revealed areas of necrosis and tissue cysts. Can this be prevented?

Answer 65

Prevention in AIDS patients: TMP/SMX when CD4 count falls below 200

Question 66

A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. After 3 days of hospitalization, the patient died. An autopsy revealed the following: Grossly, the brain was edematous and showed areas of hemorrhagic necrosis. Microscopic examination of brain tissue revealed areas of necrosis and tissue cysts. Who else is at risk for toxoplasmosis?

Answer 66

Healthy children & adults - mono-like syndrome Infants born to infected-during-pregnancy mothers - MAJOR neurological development issues Patients with severe T cell immune suppression other than AIDS

Question 67

An ultrasound preformed on a pregnant woman in her 16th week of gestation showed her fetus to have hydrocephalis and intracranial calcifications. The mother was tested and found to have IgM antibodies to Toxoplasma gondii. What kind of organism is Toxoplasma gondii?

Answer 67

Protozoan

Question 68

An ultrasound preformed on a pregnant woman in her 16th week of gestation showed her fetus to have hydrocephalis and intracranial calcifications. The mother was tested and found to have IgM antibodies to Toxoplasma gondii. How may the mother have become infected?

Answer 68

Cleaning the litter box

Question 69

An ultrasound preformed on a pregnant woman in her 16th week of gestation showed her fetus to have hydrocephalis and intracranial calcifications. The mother was tested and found to have IgM antibodies to Toxoplasma gondii. What are the manifestations at birth and the long term sequelae of congenital toxoplasmosis?

Answer 69

At birth, most commonly see: Hydrocephalis, Intracranial calcifications, Chorioretinitis Long term, see: Deafness, visual impairment, learning disabilities

Question 70

An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA. What is this organism?

Answer 70

Sporozoite protozoan

Question 71

An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA. How was she potentially infected?

Answer 71

Ingestion of contaminated water or food Outbreaks have happened due to contaminated water in pools and water parks (not susceptible to chlorination)

Question 72

An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA. Who is at risk for serious disease?

Answer 72

Immune suppressed Infants Elderly

Question 73

An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA. How would you perform a diagnosis?

Answer 73

Finding oocytes in stool Requires use of acid fast stain ELISA tests for antigen detection; PCR test also available

Question 74

An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA. What treatment would you use?

Answer 74

Nitazoxanide - immunocompetent Adjustments to anti-HIV drugs - AIDS patients Paromomycin - used with some success in immunocompromised, although generally there is no treatment

Question 75

A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool. Who is at risk of catching this?

Answer 75

Persons living in or visiting endemic areas, including SE US & Appalachian region, tropical & subtropical areas

Question 76

A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool. What can chronic infections lead to?

Answer 76

Disseminated infections if patient becomes immuno-suppressed

Question 77

A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool. Describe the pathogenesis of this organism.

Answer 77

Parasites escape from GIT in circulation (often bringing along bacteria) - larvae invade CNS, heart, urinary tract, endocrine glands

Question 78

A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool. How would you treat this?

Answer 78

Thiabendazole