Infectious Disease Flashcards
Pathogenesis of Measles
- Reservior
- Route of infection
- Binds which molecules to enter cells?
- Reservior: only humans
- Starts in RT
- Spreads to reticuloendothelial tissue
- virus binds CD46 and signaling lymphocytic activation molecule (SLAM) of T cells
- Dissemination results in shedding into urine and respiratory tract secretions before rash initiates
Patient presents with small red spots with a blue/white center on the bucal mucosa, Cough, and conjunctivitis. A few days later he develops a rash. Microscopic examination shows cells pictured below. What is the disease?
Measles (Rubeola)
- (-) ssRNA
- Giant cells: Warthin-Finkeldey cells (characteristic)
- Koplik spots also characteristic
What are possible severe outcomes of measles?
- Subacute sclerosing panencephalitis
- defective infection of CNS
- Postinfectious encephalitis
In what secretions is the measles virus found before the rash begins?
- Urine
- Respiratory tract secretions
Patient presents with swelling of the parotid glands and testicular pain.
- What is the disease?
- How is it spread?
- What are other complications?
- What cell type is found in excess in the parotid glands?
- Mumps
- by aerosols
- Complications:
- Orchitis (testicular pain)
- Oophoritis
- Aseptic meningitis
- Mononuclear cell infiltrate, Neutrophils in lumen of parotids
Patient presents with history of fever, headache, pharyngitis, and abdominal pain. Currently presents with paralysis (LMN signs).
- What is the disease?
- How is it spread?
- What are CSF findings?
- Poliomyelitis (poliovirus)
- Fecal-oral route, so general symptoms are GI
- CNS shows
- elevated WBCs (pleotropy)
- slight increase in protein (FA)
- no change in glucose (FA)
Patient presents with fever, pharyngitis, and abdominal pain in addition to nuchal rigidity and muscle and back pain. CSF shows increased WBCs.
- What is the disease?
- What is the cause?
- How is it spread?
- Aseptic meningitis
- Poliovirus (major illness)
- fecal-oral route
Patient presents with rash on trunk, lymphadenopathy, and arthralgia. In addition they have a fever, headache, stiff neck, and altered CNS function. Lab tests show elevated IgM in the CSF.
- What is the disease?
- What is the cause?
- How is it transmitted?
- What are the reserviors?
- Encephalitis
- West Nile Virus
- blood, transplacentally
- Reservior: crows, birds
Patient presents with fever, rash, myalgia, joint and bone pain, and vomiting. Blood has increased leukocytes. History of travel to S. America.
- What is the disease?
- What is the pathogenesis?
- Dengue Fever
- Path:
- circulates in monocytes
- Lysis of cells causes release of TNF and IFN-gamma
- TNF: increased vasc permeability
- complement cascade activated
- C3a and C5a increase vasc perm
Patient presents with 3 day fever, rash, myalgia, joint and bone pain, and vomiting. Also presents with gingival hemorrhage.
- What is the disease?
- Dengue hemorrhagic fever.
- May progress to hypovolemic shock
What are complications of Dengue hemorrhagic fever?
- Thrombocytopenia
- DIC
- Hemorrhage
HSV
- Nuclear material
- Transmission
- Location of latent infection
- Microscopic presentation
- dsDNA
- sex, saliva, vesicle fluid
- HSV-1: trigeminal ganglia; HSV-2: sacral ganglia
- Multinucleated giant cell with eosinophilic intranuclear inclusions (Cowdry inclusions, Picmonic)
Patient presents with gingivitis with ulcers and perioral lesions. Lab tests find dsDNA.
- What is the disease?
- What is the cause?
- Gingivostomatitis (oral-facial herpes)
- HSV (1)
Patient presents with dysuria and painful, pruritic vesicles with urethral discharge. Lab analysis shows dsDNA.
- What is the disease?
- What is the cause?
- genital herpes
- HSV-2
Patient presents with headache, fever, vomiting, stiff neck, cerebral edema, and seizures. Patient also has anosmia and memory loss.
- What is the disease?
- What is the cause?
- What is the pathology?
- Viral encephalitis
- HSV-1
- Path:
- All viral:
- lymphocytic infiltrate
- glial proliferation in meninges, cortex, white matter
- HSV:
- necrosis in temporal lobe
- All viral:
Patient presents with headache, fever, vomiting, stiff neck, photophobia and myalgia. Lab tests show dsDNA.
- What is the disease?
- What is the cause?
- Viral meningitis
- HSV-2
Patient presents with acute onset of pain in eye, conjunctivitis with a discharge, blurred vision, and “dendritic body” lesion shown below.
- What is the disease?
- What is the cause?
- Keratoconjunctivitis
- HSV (1)
Patient presents with history of pain, burning, and itching around mouth. A Papule appeared that turned into a vesicle and is now a crust.
- What is the disease?
- What is the cause?
- Herpes labialis (cold sore)
- HSV (1)
Which type of HSV causes genital infection?
HSV-2
CMV
- Reservoir
- Transmission
- Pathology
- Characteristic cytology
- Clinical Manifestations
- Humans only
- body fluids, perinatal, congenital
- prevent MHC I expression
- Owl’s eye cell
- Clinical:
- Cytomegalic inclusion disease
- Perinatal infection
- Mono
- Hepatitis
- In immunocompromised: Pneumonia, chorioretinitis, esophagitis, CNS infection
Patient presents with fatigue, fever, pharyngitis, and mild hepatitis. Lab tests are negative for heterophile Abs. Cells found are shown below.
- What is the disease?
- What is the cause?
- Mononucleosis
- CMV
- EBV is positive for heterophile Abs
Patient presents at birth with jaundice, rash, and respiratory distress. Cytology below.
- What is the disease?
- What is the cause?
- Cytomegalic inclusion disease
- CMV
What can be the long-term effects of Perinatal infection by CMV?
- loss of hearing
- developmental effects on intelligence
What are the diseases CMV causes in immunocompromised patients?
- Chorioretinitis
- Esophagitis
- ulcerations, difficulty swallowing, diarrhea
- Hemorrhagic pneumonia
- Polyradiculopathy
- ascending weakness, loss of deep tendon reflexes, loss of bowel and bladder control
Patient presents with fever, headache, and sore throat in addition to a rash that started on the head and has spread to the trunk. Some spots are papules, some are vesicles, some are crusts.
- What is the disease?
- What is the cause?
- How is it transmitted?
- Chickenpox
- VZV
- Respiratory secretions or vesicle fluid
Patient has history of pain and neuralgia. A few days later a rash appears. The rash is along the lines of a dermatome and does not cross the midline.
- What is the disease?
- What is the cause?
- What is the Pathogenesis?
- What is the infiltrate?
- Shingles
- VZV
- Path:
- latent infection in sensory nerve (dorsal root ganglia)
- neuronal necrosis
- Mononuclear infiltrate
HBV
- Genetic material
- Reservior
- Transmission
- circular, partially-dsDNA (some parts are ssDNA)
- enveloped
- humans only
- body fluids, transplacental
What is the pathogenesis and end result of chronic hepatitis?
- Path:
- mononuclear infiltrate
- Fibrosis
- Necrosis
- In chronic active, no anti-s or c Ab
- End result:
- cirrhosis
- hepatocellular carcinoma
To what does EBV bind to enter B-cells?
CD-21
What proteins are expressed in EBV infection?
- EB Nuclear Ag (EBNA)
- EBNA-2 = cyclin D expression to stimulate cell cycle
- latent protein
- Latent membrane protein (LMP)
- LMP-1 activates B-cells
What events are associated with transformation in EBV?
- t8;14 w/ c-myc gene
- LMP-1 activates B cells
- EBNA-2 stimulates cyclin D and cell cycle progression
Patient presents with with fever, fatigue and pharyngitis. Lab tests are positive for heterophile Abs and the cells shown below.
- What is the disease?
- What is the cause?
- How is it transmitted?
- What is the cell called?
- Mononucleosis
- EBV
- intimate contact (eg: saliva)
- Downy cell
Pathogenesis of EBV
HPV
- Transmission
- Pathogenesis (molecular and cellular)
- resulting disease
- direct contact or inanimate objects with compromised skin
- Path:
- integrates dsDNA genome into host
- E6 and E7 are expressed and inhibit cell cycle regulation
- Hyperplasia of skin and cancer results
- koilocytic changes to epithelium
- Disease:
- warts (Condyloma acuminatum)
- cervical squamous cell carcinoma and adenoma
What is pictured?
Cervical squamous cell carcinoma
Swirls are called keratin pearls
Which of the staphylococcus produce coagulase?
S. aureus
In S. aureus infection,
- What inhibits opsonization?
- What inhibits chemotaxis and phagocytosis
- What is a common resistance?
- What toxins are produced?
- What inhibits opsonization?
- Protein A
- What inhibits chemotaxis and phagocytosis?
- capsule/biofilm
- What is a common resistance?
- beta-lactamase
- What toxins are produced?
- alpha-toxin (cytolytic/necrosis)
- Leukocidin (cytolytic for macrophage)
What super antigens are produced by S. aureus? What diseases do they cause?
- Enterotoxins
- food poisoning
- Pyrogenic exotoxins (TSST-1)
- Toxic shock syndrome
- Exfoliatins
- Scalded skin syndrome
- impetigo
What is pictured?
Staphylococcus
Characteristic grape-bunch formation
Patient presents with both fluid-filled blisters and crusts. Lab tests are catalase (+) and coagulase (+).
- What is the disease?
- What is the cause?
- With what toxin is it associated?
- Bullous impetigo
- S. Aureus
- exfoliative toxin/epidermalytic toxin
Patient presents with a diffuse rash and flaccid bullae. Nikolsky’s sign is positive (epidermis easily separates with slight pressure). Lab tests are catalase (+) and coagulase (+).
- What is the disease?
- What is the cause?
- With what toxin is it associated?
- Scalded skin syndrome
- S. aureus
- exfoliative toxin
What is the difference between SIRS, sepsis, and septic shock?
- SIRS (systemic inflammatory response syndrome)
- fever, increased WBC count, HR, respiration
- No evidence of infection
- Sepsis
- same as above but with infection
- Septic shock
- same as above but with organ dysfunction and hypotensive shock (BP <60)
Patient presents with fever, chills, petichiae, and heart murmur. Lab tests are positive for catalase and coagulase.
- What is the disease?
- What is the cause?
- Native valve infective endocarditis
- S. aureus
Patient presents with acute onset of fever, dyspnea, tachypnea, and a mucopurulent sputum. Lab tests are positive for catalase and coagulase.
- What is the disease?
- What is the cause?
- Pneumonia
- often hemorrhagic necrosis with absess/ pneumatocele formation
- S. aureus
What connective tissue disorders are associated with S. aureus?
- Osteomyelitis
- bone destruction, pain, swelling, fever
- Septic arthritis
- local inflammation, pain, and swelling of one joint
Both may progress to sepsis
Patient presents with fever, myalgia, rash, and erythema that blanches on pressure. Lab tests are positive for catalase and coagulase.
- What is the disease?
- What is the cause?
- With what toxin is it associated?
- Toxic shock syndrome
- S. aureus
- TSST-1
What are the virulence factors of S. pyogenes?
- M protein
- Streptolysin S
- O2 stable
- Streptolysin O
- O2 labile
- SPEA
- scarlet fever and strep toxic shock
Patient presents with pharyngitis and a rash that blanches with pressure with circum-oral pallor. After almost a week the rash desquamates. Lab tests are negative for catalase but show SPEA.
- What is the disease?
- What is the cause?
- With what toxin is it associated?
- Scarlet fever
- Strep. pyogenes
- SPEA (exotoxin)
Patient presents with pharyngitis and a raised lesion with distinct borders on the face. Lab tests are catalase negative.
- What is the disease?
- What is the cause?
- Erysipela
- Strep. pyogenes
Patient has history of papule that developed into vesicle, then pustule, and now has a thick, amber-colored crust. Lab tests are catalase negative.
- What is the disease?
- What is the cause?
- Impetigo
- Strep. pyogenes
What is the most common cause of life-threatening invasive bacterial infection in neonates?
strep. agalactiae
Infant presents with respiratory distress, cyanosis, hypotension, and jaundice 10 hours after birth.
- What is the disease?
- What is the cause?
- With what is it associated?
- What are some complications?
- Early onset neonatal infection by Strep. agalactiae
- Associated with obstetric complications
- Complications:
- septicemia (60%)
- pneumonia (30%)
- meningitis (10%)
Patient presents with septicemia and meningitis 2 weeks after birth.
- What is the disease?
- What is the cause?
- Late onset neonate infection by Strep. agalactiae
What infections are caused by strep. agalactiae in adults?
- bacteremia/septicemia (30-40%)
- skin and soft tissue (15-40%)
- UTI (5-15%)
Streptolysin S or O is indicative of which bacteria?
Strep. pyogenes
Pneumolysin O is indicative of which bacteria? What is its function?
Strep. pneumoniae
Function: cytotoxic; causes alveolar edema and hemorrhage
Patient presents with fever, chills, chest pain, and cough productive of rusty-colored sputum. There is consolidation of the lungs restricted to lobar compartments.
- What is the disease?
- What is the cause?
- What is the composition of the infiltrate?
- lobar pneumonia
- Strep. pneumoniae
- neutrophils followed later by macrophages
What diseases are most commonly caused by Strep. pneumoniae?
- Meningitis
- Otitis media
- Pneumonia
- Sinusitis
**Think MOPS
What are the virulence factors of Strep. pneumoniae?
- capsule
- pneumolysin O
- O2-labile hemolysin that causes alveolar edema and hemorrhage