Micro/Immuno Flashcards
Contained infection by this is called “valley fever” or “desert rheumatism”
What is it?
Coccidioides immitis
Pathogenesis of Histoplasma capsulatum involves what immune cell? How?
Macrophages – engulfs spores, which survive by producing bicarb and ammonia to raise pH and inactivate hydrolytic enzymes.
Immunocompromised geriatric patient has cough, chest pain, hemoptysis, weight loss, other flu-like symptoms, and ulcerated lesions on tongue. Exam/Lab/Imaging/Biopsy: cavitary lung lesions, granulomas in liver and spleen, pancytopenia.
What is it?
Histopalsmosis (H. capsulatum)
A patient has a fungal infection that requires treatment w/ amphotericin B, but he has kidney problems.
What do you do?
Give liposomal form of Amphotericin B
Histoplasma capsulatum has 2 types of asexual spores:
Tuberculate macroconidia and Microconidia.
–Which type is infectious?
–Which type has thicker walls?
–Which type has Fingerlike projections?
–Which type can be grown in 25C Sabouraud’s agar?
- -Infectious = microconidia
- -Thicker = tuberculate macroconidia
- -Projections = tuberculate macroconidia
- -Agar = tuberculate macroconidia
(unexposed/contained/disseminated/cleared) Coccidoides:
PPD w/ coccidioidin or spherulin:
–When is it (+)?
–When is it (-)?
(+) = exposed w/ cleared or contained infection
-) = unexposed, disseminated infection (in immunosuppressed
What are red, tender nodules on exterior surfaces like lower legs that develop due to cell-mediated hypersensitivity to fungal antigens?
Erythema nodosum
What are the 4 Systemic Mycosis organisms?
- Coccidioides immitis
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Paracoccidioides brasiliensis
Which systemic mycosis has the following endemic areas:
- -Eastern North America and Great Lakes region?
- -Rural Latin America?
- -Ohio and Mississippi River valley?
- -Southwest US, Latin America?
Blastomyces dermatitidis
Paracoccidioides brasiliensis
Histoplasma capsulatum
Coccidioides immitis
What dimorphic fungus has a mold for that is hyphae w/ small pear-shaped conidia and a yeast form w/ doubly refractive wall and a single broad-based bud?
Which form is found in tissue vs. culture?
Blastomyces dermatitidis
- -Tissue biopsy –> yeast cells
- -Culture –> hyphae
What dimorphic fungus has a mold for w/ thin, septate hyphae and a yeast form that is thick-walled w/ multiple buds?
Paracoccidioides brasiliensis
What are the 5 Opportunistic Mycosis organisms/groups?
- Candida
- Cryptococcus neoformans
- Aspergillus fumigatus + others
- Mucor/Rhizopus
- Fusarium spp
An AIDS patient accidentally ingests bird poop (specifically pigeon).
What mycosis is he at risk for?
Cryptococcus neoformans
Patient w/ Hx of steroid use, malignant disease, previous transplant, and HIV+ has a slight fever and slight stiff neck w/ subcutaneous nodules. Lab: CSF stain w/ India ink shows yeast w/ wide capsule. Serology: CrAg.
What is it?
Cryptococcus neoformans
Culture shows: mold only – septate hyphae w/ V-shaped branches, conidia forming radiating chains.
What is it?
Aspergillus fumigatus
- -Virulence factors: gliotoxin (immunosuppressive), toxic metabolites, proteases
- -Impairs macrophage and neutrophil responses
- -Airborne infectious conidia
- -Colonizes abraded skin, burns, cornea ,ear, sinuses
What is it?
Aspergillus fumigatus
Patient w/ asthma and CF has coughs of brownish substance w/ blood in sputum, fever, wheezing. Doesn’t respond to Abx. CXR: “grape cluster”/”hand in mitten” clusters in bronchi. Labs: Eosinophilia, high IgE. Treated w/ omalizumab and sinus surgery.
What is it?
Pathogenesis?
–Allergic bronchopulmonary aspergillosis (ABPA)
- -Hypersensitivity to bronchi infection by aspergillus.
- -Exacerbates asthma, CF
Patient w/ Hx of alcoholism, collagen-vascular disease, chronic granulomatous disease, COPD, and long-term corticosteroid use has subacute pneumonia (ineffective Abx), fever, cough, night sweats, weight loss, and ineffective TB treatment.
What is it?
Pathogenesis?
–Chronic necrotizing pulmonary aspergillosis (CNPA)
- -Hyphae invade lung tissue –> pneumonia w/ hemoptysis and granulomas
- -Rare, hard to diagnose
Patient w/ Hx of TB and CF has cough, fever, severe hemoptysis. CXR: fungus ball that changes position when sitting up vs. lying down.
What is it?
Pathogenesis?
–Aspergilloma
- -Fungus balls form at site of cavitary lesion left by past TB, pulmonary mycosis, or CF.
- -Can cause lethal pulmonary hemorrhage
Patient w/ Hx of COPD on corticosteroids and A LOT of immunosuppressives has fever, cough, pleuritic chest pain, worsening hypoxemia. Chest CT: “halo sign”. Labs: high serum glactomannan antigen.
What is it?
Pathogenesis?
–Invasive aspergillosis
- -Rapid, progressive invasion of blood vessels –> infarction, hemorrhage, necrosis
- -“Halo sign” = pulmonary infarction surrounded by alveolar hemorrhage
Patient w/ Hx of DM, burns, leukemia, IV steroids, TNFa blocker, or iron overload has and infection that causes brain, eyes, lungs, skin, GI or CNS failure due to impaired blood flow. Biopsy: nonseptate hyphae w/ broad irregular walls, branches at right angles
What is it?
–Mucor/Rhizopus/Absidia
Where might an infection by Fusarium spp develop in an immunocompetent patient?
Treatment?
–Under fingernails or in the cornea
–Amphotericin B, voriconazole, posaconazole
What is the most common Fusarium organism for both corneal and disseminated infections?
Fusarium solani
Fusarium microscopic morphology:
Banana-shaped macroconidia w/ “foot cell” at base
What organism is uniquely acid-fast staining and an obligate aerobe?
Mycobacterium tuberculosis
5 Important structural components of M. tuberculosis:
- Mycolic acids – acid fastness
- Wax D – adjuvant
- Phosphatides – caseation necrosis
- Cord factor (trehalose dimycolate) – virulence, microscopic serpentine appearance
- Phtiocerol dimycocerosate – lung pathogenesis
Exudative TB lung lesion, usually lower lobe, w/ acute inflammatory response and draining lymph node.
What is it called?
Ghon Complex
TB lesion w/ central area of infected Langerhans’ giant cells surrounded by epithelioid cells
What is it called?
Granulomatous Lesions
Old TB granuloma surrounded by fibrous tissue, central caseation necrosis. Healed by fibrosis and calcification.
What is it called?
Tubercule
TB is controlled by what type of immunity?
Cell-Mediate Immunity (CMI) – CD4+ Th1 cells, macrophages, gamma-interferon
Patients receiving what drug for Rheumatoid Arthritis or Crohn’s disease may reactivate latent TB infection?
Remicade
What is it called when TB disseminates to cause osteomyelitis?
Pott’s Disease
–Osteomyelitis = infection of bone or bone marrow
What is cervical adenitis associated w/ TB called?
What other organism can cause it?
- -Scrofula
- -M. scrofulaceum in pediatric patients
PPD skin test measures what type of hypersensitivity?
Type IV – Delayed Hypersensitivity
What are the 4 groups of Atypical Mycobacteria?
- -Group 1: Photochromogens – produce pigment in light
- -Group 2: Scotochromogens – produces pigment in dark
- -Group 3: Nonchromogens – no pigment
- -Group 4: Rapidly growing mycobacteria – no pigment
What mycobacteria has armadillos as a reservoir?
M. leprae
CMI response difference in Tuberculoid vs. Lepromatous leprosy?
–Tuberculoid = strong CMI response –> CD4+, Th1, IFN-gamma, IL2, IL12, (+) skin test
–Lepromatous = poor CMI response –> useless Th2, nonprotective antibodies, (-) skin test
Where do M. leprae replicate?
Intracellular = skin histiocytes, endothelial cells, Schwann nerve cells
Tuberculoid or Lepromatous leprosy has:
- -Granulomas containing giant cells?
- -Many bacilli in skin, mucous membrane
- -Immunogenic nerve damage
- -(+) Lepromatin Skin test
- -Foamy Histiocytes
Tuberculoid–Granulomas containing giant cells?
Lepromatous–Many bacilli in skin, mucous membrane
Tuberculoid–Immunogenic nerve damage
Tuberculoid–(+) Lepromatin Skin test
Lepromatous–Foamy Histiocytes
What type of leprosy?
- -Hypopigmented macular or plaque-like skin lesions, thickened superficial nerves, anesthesia of skin lesions
- -Multiple nodular skin lesions, “leonine facies”
Tuberculoid–Hypopigmented macular or plaque-like skin lesions, thickened superficial nerves, anesthesia of skin lesions
Lepromatous–Multiple nodular skin lesions, “leonine facies”
Pseudomonas aeruginosa:
- Gram ___
- Shape?
- Aerobic/Anaerobic status?
- Fermenter/nonfermenter?
- Oxidase ___
- 2 exotoxins are?
- -Gram (-)
- -Rod
- -Strict aerobe
- -Nonfermenter
- -Oxidase +
- -Pyocyanin and pyoverdin
This pneumonia causing bacteria is also associated with foot rot in swamp-developed military.
B. cepacia
Cepacia syndrome is accelerated pulmonary couse w/ rapidly fatal bacteremia in what patient population?
Cystic Fibrosis pneumonia patients
In cultures of what pneumonia causing bacteria do you look for pigments, metallic sheen, and fruity aroma?
Pseudomonas aeruginosa
Foot rot in swamp-deployed military is caused by what organism?
Burkholderia cepacia
What are the 2 weaponizable pneumonia causing organisms?
B. pseudomallei
B. mallei
Blood culture and gram stain of a pneumonia patient shows “wrinkled” colony morphology
What organism?
B pseudomallei
Developing-nation vetrinarians and farmers develop a flu-like pneumonia. They recall having encountered horses with a disease called “Glanders”
What organism?
B mallei
Patient who works at pet shop had a sick bird last week and comes in with a severe pneumonia.
What organism?
Chlamydia psittaci
Legionella:
- Stain? Gram ___
- Shape?
- [Intra/Extra]cellular?
- Motility?
- human-to-human transmission?
- POOR STAINING, Gram (-)
- Rod
- Facultative intracellular
- Infectious = motile w/ flagella
- BUT replicative = nonmotile, intracellular
- NO transmission
What are the 3 ways a Legionella infection clinically presents?
1–Asymptomatic seroconveresion
2–Pontiac Fever = flulike, immunogenic symptoms in previously healthy patient
3–Legionnaires Disease = pneumonia w/ kidney involvment and diarrhea in previously ill
What human cells do Legionella infect?
Human alveolar macrophage (in lung)
Old, smoking, grandpa (male) w/ HIV (immunosuppression), COPD and CHF (chronic heart or lung disease), and some kind of chronic swallowing disorder has pneumonia symptoms.
What kind of presentation of what pathogen?
Legionella – Legionnnaires Disease
Q fever is caused by what organism?
Coxiella burnetii
What places are associated with Coxiella infection (Q fever)?
- -Europe: Netherlands, France, Spain
- -Iraq
When you see pneumonia w/ hepatitis, think what organism?
Coxiella
What bacterial organism uniquely has:
- -no cell wall
- -cholesterol in membrane
- -“fried-egg” colonies
- -incomplete immunity
Mycoplasma pneumoniae
“Walking pneumonia” in which CXR looks worse than the patient looks. Has “cold-agglutinins” and becomes anemic.
What organism?
Mycoplasma pneumoniae
Influenza A vs Influenza B
- -Which usually causes pneumonia?
- -Which usually causes rhinitis/pharyngitis
- -Pneumonia = A
- -Rhinitis/pharyngitis = B
What virus causes croup and lower respiratory tract disease in children?
Parainfluenza virus
What virus causes pneumonia and bronchiolititis in young children?
Respiratory Syncytial virus (RSV)
SARS and MERS are caused by what virus?
Coronavirus – (+) ssRNA virus
Orthomyxoviridae vs. Paramyxoviridae:
- -Which is segmented?
- -Which replicates in cytoplasm?
- -Which is enveloped?
- -Segmented = Ortho
- -Cytoplasmic replication = Para
- -Evenloped = BOTH
Close contact in day cares, military camps, swimming clubs increases risk for this icosahedral, naked, linear DNA virus
Adenovirus
Haemophilus influenzae requires what unique additives to chocolate agar to grow in culture?
Factor X = heme
Factor V = NAD
Which serotype of H. influenzae causes most severe disease?
Type B –> meningitis, epiglottitis, pneumonia, sepsis
What age is most likely to get H. influenzae B infections?
6mo-6yr, peak = 6mo-1yr
Whooping cough is caused by what organism?
Bordetella pertussis
What Bordetella pertussis virulence factor attaches the bacteria to cilia of epithelial cells lining respirtory tract?
“Filamentous hemagglutinin” pilus
What are the 2 exotoxins of Bordetella pertussis
- -Pertussis toxin = kill ciliated cells, inhibit chemokines –> lymphocytosis
- -Tracheal cytotoxin = kills ciliated cells
What are the 2 types of Bordetella pertussis vaccine?
- -Acellular = pertussis toxiod
- -Heat-killed bacterium
