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55 Cards in this Set
- Front
- Back
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The quantitative ability of an agent to cause disease which involves invasiveness and toxigenicity.
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Virulence
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What diseases are caused by PrP?
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Prion proteins (PrP) can cause Kuru Creutzfeldt-Jakob disease (CJD) Bovine spongiform encephalopathy (Mad Cow) (BSE) |
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The ability of an infective agent to cause disease.
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Pathogenicity
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List 4 ways microbes evade immune system.
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1) Replication at sites inaccessible to immune response. 2) Resistance to complement mediated lysis and phagocytosis. 3) Varying antigen and shedding antigens. 4) Direct damage of host immune system. |
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List the 5 major histological patterns of tissue response or reaction.
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1) Suppurative - acute 2) Mononuclear/granulomatous - ALL chronic inf 3) Cytopathic-cytoproliferative - viral 4) Necrosis - toxins 5) Chronic inflammation/scarring - final common pathway of ALL infections |
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List toxins and bacteria that produce them.
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cholera enterotoxin - Vibrio cholera diphtheria toxin - Corynebacterium diphtheria superantigen enterotoxin - S. auerus leukocidin - Strep. erysipelas |
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List forms of viral infections and main feature.
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1) Abortive - cell is non-permissive 2) Acute/transient - short duration 3) Chronic/latent - virus present but not active 4) Chronic productive - continued low level viral replication but with relapses |
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Features of Measles.
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- ss-RNA virus. Have hemagglutinin protein that binds to CD46, SLAM, Nectin 4. - 3Cs - Cough, Coryza, Conjunctivitis - Rash is HS rxn to viral antigen with predominance of mononuclear cells. - Koplik spots in inner cheek - Warthin-Finkeldy cells in lymphoid organs |
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Characteristic white or gray ulcerated mucosal lesions occurring in the oral cavity in inner cheek near opening of Stensen's duct.
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Koplik pots
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Features of mumps.
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Caused by Paromyxovirus (ss-RNA, encapsulated) commonly infecting parotid gland. Droplet spread. Invasion, replicate in T-cells, spread through blood to salivary gland. May also spread to CNS (encephalitis), kidneys, pancreas, testes (orchitis) |
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Features of polio.
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Encapsulated ss-RNA virus. Uses human CD155 to gain entry into cells. Feco-oral route. Infects oropharynx-saliva-swallowed-multiplies in intestinal mucosa and lymph nodes. Can cause limb deformities and paralysis with CNS involvement.
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Features of dengue.
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Multiplies in macrophages. Hemorrhagic form due to thrombocytopenia, increased vascular permeability and endothelial dysfunction.
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Features of herpes virus.
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- Alpha group infects epithelial cells and produces latent infections in neurons. HSV-1, -2, VZV - Beta group infects lymph nodes and produces latent infections in variety of cell types. CMV, HHV-6, -7 -Gamma group latent infection in lymphoid cells. EBV, HHV-8 (Kaposi's sarcoma associated herpesvirus (KSHV) |
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Features of HSV.
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Encapsulated ds-DNA virus. Herpes simplex virus-1 & -2 causes acute epithelial infections then latent infection in neurons. 1 causes most cold sores, 2 causes most genital herpes. Main cause gingivostomatitis, Herpetic Whitlow, corneal lesions (indirectly), and HS encephalitis is HSV1. Envelope attaches to HVEM, nectin-1, heparan sulfate particle.
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Features of VZV/HHV3.
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Lipid Enveloped tegument enclosed capsid with ds-DNA. Varicella-Zoster virus/Human herpes virus causes chicken pox acutely in mucous membranes, skin, neurons and Shingles/herpes zoster chronically in DRG. Shingles lesions distributed unilaterally with intense itching, burning, pain. Can cause Ramsay Hunt syndrome (facial paralysis due to geniculate nucleus, HZ opthalmia (ophthalmic branch CN5).
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Features of CMV.
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Cytomegalovirus. Enveloped ds-DNA. Can be transmitted transplacental, neonatal, respiratory, genital, fecal-oral, iatrogenic. Latently infects monocytes and bone marrow progenitors. Infects parenchymal epithelial cells, neurons, alveolar macrophages, lung epithelial and endothelial cells, kidney tubular epithelial and glomerular endothelial cells.
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Features of HBV.
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Hepatitis B virus. Enveloped circular DNA, not fully double-stranded with one end linked to viral DNA polymerase. Infects hepatic cells with long-term viral replication that causes recurrent immune-mediated liver injury (by cytotoxic CD8+ T-cells). Can cause cirrhosis and hepatocellular carcinoma.
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Features of EBV.
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Epstein-Barr virus. Lipid enveloped tegument enclosed capsid with ds-DNA. Causes infectious mononucleosis. Infection of epithelial and B cells-becomes blood-borne-spreads to other organs. Lymphocytosis, atypical lymphocytes, hepatomegaly, splenomegaly, lymphyadenitis. Gp120 binds to CCR1&2 and MHC2.
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Features of Staphylococcus.
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Gram(+) cocci in clusters. Staph produce catalase, coagulase (aureus), hyaluronidase, staphylokinase (fibrinolysis), proteinases, lipases, exotoxins (alpha-hemolysin, beta-sphingomyelinase, delta-detergent, gamma-hemolysin), leukocidin, exfoliative toxin (A/B toxin cleaves desmoglein 1), TSS toxin (super-antigen prototype), enterotoxin (food poisoning), protein A
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Features of Staph infections.
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Respiratory infection, osteomyelitis, endocarditis, TSS, skin infection. Furuncle/boil/carbuncle, lung abscess, Staphylococci scalded skin syndrome/"Ritter's Disease" caused by exfoliative toxins A & B cleaving desmoglein-1 develops into sunburn like rash over entire body that evolves into fragile bullae leading to partial/total skin loss. |
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Features of Streptococci.
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Gram(+) cocci in strips or pairs. Produce capsule, M-protein, complement C5a peptidase, exotoxin (groups A, C Strep), pyrogenic toxin (fever & rash in scarlet fever), pneumolysin (tissue dmg), high molecular weight glucans,
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Features of Strep infections.
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1) Erysipelas - red malar rash by exotoxins from Group A & C Strep. 2) Strep pharyngitis - epiglottic swelling & punctate abscesses of tonsillar crypts 3) Scarlet fever - pyrogenic toxin causing pharyngitis, fever, red rash over trunk and inner aspects of extremities. |
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Features of Corynebacterium diphtheria.
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Gram(+) rods that colonize oropharynx transmitted by aerosols or skin shedding. Produces only phage-encoded A-B toxin that blocks host cell protein synthesis. Produces pseudomembrane & toxin-mediated myocarditis. Vaccine protects from toxin, not colonization.
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Features of diphtheria.
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Release of exotoxin causes epithelial necrosis and dense fibrino-suppurative exudate that coagulates on ulcerated necrotic surface into a tough, dirty-gray to black pseudomembrane at the back of the throat.
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Features of listeria monocytogenes.
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Gram(+) rods that cause severe food-borne infection. Internalins bind to E-cadherins on epithelial cells and induce internalization. Lysteriolysin O and phospholipases help bacteria break out of lysosome. ActA induces actin polymerization propelling bacteria to adjacent cells. IFN-gamma from NK and T-cells provide protection.
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Features of listeriosis.
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Food borne infections through dairy/meat products. Amnionitis in pregnancy. Granulomatosis infantiseptica in neonates. Disseminated listeriosis & meningitis in immunosuppressed. Focal abscesses alternate with grayish or yellow nodules of necrotic tissue debris in liver, lungs, spleen, lymph nodes.
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Features of Bacillus anthracis.
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Gram(+) bacillus that causes anthrax - cutaneous, inhalational (Woolsorter's dse), gastro-intestinal. Causes necrosis with exudative inflammation with infiltration by neutrophils and macrophages. Tx with ciprofloxacin.
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Features of anthrax. (M0=macrophages) |
Fever, dyspnea, hypotension and death with 90% mortality rate. Lungs with foci of hemorrhage, perihilar interstitial pneumonia with macrophages found in interstitium, not alveoli, pulmonary vasculitis. Mediastinal lymph nodes show lymphocytosis, M0 with phagocytosed lymphocytes, fibrin-rich edema. Cutaneous anthrax ends in lymphadenopathy leads to vesicle ruptures and covered by black eschar.
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Features of Nocardia asteroides.
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Gram(+) bacilli that causes opportunistic infections.
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Diseases caused by Gram(+) bacteria.
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Strep and staph infections. Diphtheria Listeriosis Anthrax Nocardiosis |
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Diseases caused by Gram(-) cocci.
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Gonorrhea Bacterial meningitis Meningococcemia Whooping cough |
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Features of Neisseria gonorrhea.
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Gram(-) diplococci attach to epithelial cells of mucous membranes. Pili, Protein I & III (pore), Protein II (OPA protein, self adhesion, cell entry), lipooligosaccharide (endotoxin), Lip protein (heat mod), iron binding protein, IgA-1 protease (inactivates IgA)
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Features of gonorrhea.
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Males - urethritis, purulent exudate, pain Female - asymptomatic, pelvic inflammatory dse if untreated. Children - GCPN Lack complement protein - disseminated gonococcal dse (GC arthritis-dermatitis syndrome). |
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Features of N. meningitidis.
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Gram(-) diploccoci attach to epithelial cells of mucous membranes. Capsular polysaccharide (inhibit opsonization), pili, Class 1,2,3 protein (pore), Class 5 (Opa), lipo-oligosaccharide (endotoxin)
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Features of meningococcal infection.
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-Septicemic infection, shock, spreads to subarachnoid space causing meningitis. -Waterhouse-Frederichsen syndrome bilateral adrenal hemorrhage, shock, DIC, vasculitis purpura -Meningococcal meningitis causes polymorphonuclear (neutrophilic) infiltration of meninges, |
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Features of Bordetella pertussis. (M0=macrophages) |
Gram(-) coccobacilli. Pili, filamentous hemagglutinin adhesion (binds to CHO on respiratory epithelial cells, CR3 on M0), pertussis A-B toxin (exotoxin, A-tox paralyzes cilia, B-tox binds to TLR-R & allows A tox to enter cell), adenylyl cyclase toxin (ATP to cAMP, inhibits phagocytosis & ox burst in neutrophils and apoptosis of M0), dermonecrotic toxin, hemolysin, tracheal cytotoxin
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Features of Whooping cough.
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Invasion of resp. tract. Adhesion to epithelial cells and paralysis of cilia. Toxin release. Coughing, lymphocytosis. Focal necrosis of epithelium, neutrophil infiltration, peribronchial inflammation, interstitial pneumonia. Obstruction of small bronchioles by mucus plugs (mucosal erosion). Atelectasis, decreased oxygenation. Convulsion.
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Diseases caused by Gram(-) bacilli.
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Pseudomonas aeruginosa infection Chancre (Haemophilus ducreyi) Granuloma Inguinale (Klebsiella granulomatis) Plague/Black Death (Yersinia pestis) |
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Diseases caused by Mycobacteria.
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Tuberculosis M. avium & M. intracellulare Complex (MAC) Leprosy or Hansen's Disease |
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Diseases caused in various organs by TB.
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Meninges - TB meningitis Kidneys - renal tuberculosis GI - intestinal TB Adrenal glands - Addison disease Bones - osteomyelitis Fallopian tubes - Salpingitis Vertebrae - Pott disease Lymph nodes - lymphadenitis (Scrofula-cervical) |
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Features of MAC.
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Mycobacterium avium-intracellulare complex. Common in AIDS. Wide dissemination. Foamy macrophages or histiocytes filled with acid-fast bacilli (AFB).
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Features of leprosy.
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Mycobacterium leprae. Cannot be cultured in vitro. Benign tuberculoid to severe lepromatous leprosy. Tuberculoid has focal dry scaly lesions that lack sensation. Lepromatous is disfiguring skin nodularity with Leonine face,
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Features of Spirochetes.
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Gram(-) corkscrew shaped with axial flagella around helical protoplasm. Causes syphilis (Treponema pallidum) and lyme disease (Borrelia burgdoferi) and recurrent fever (Borrelia recurrentis).
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Features of Syphilis.
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Treponema pallidum. Causes painless hard chancre (versus ducreyi painful soft chancre). Primary syphilis hard chancre. Secondary if untreated dissemination to skin/palms/soles maculopapular, pustular or scaly rash. Condylomata Latum plaques on moist areas of skin. Silver-gray erosions on mucous membranes. Tertiary if untreated leads to aortitis, aortic aneurysm, neurosyphilis, gumma.
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What is Hutchinson's Triad?
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In Late Childhood/Tardive congenital syphilis. Interstitial keratitis, Hutchinson teeth, 8th nerve deafness
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Stages of Lyme disease.
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Caused by Borrelia burgdorferi in deer ticks. Stage 1 localized infection at site of tick bite. Expanding area of redness with pale center. Stage 2 disseminated hematogenously w/ 2ndary skin lesions, lymphadenopathy, migratory arthritis, CNS, Cardiac involvement. Stage 3 is persistent infection with destructive chronic arthritis, polyneuropathy, encephalitis.
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Diseases caused by anaerobic bacteria.
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Clostridial infections - Gram(+) bacillus C. perfringes/septicum - cellulitis, gas gangrene, C. tetani - tetanus C. botulinum - botulism C. difficile - pseudomembranous colitis |
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Features of Clostridium.
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Secretes 14 toxins - alpha most important contains phospholipase C (degrades lecithin, destroys RBCs, platelets, ms cells (myonecrosis) and sphingomyelinase (nerve damage).
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Features of Chlamydia.
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Disease caused by obligate intracellular bacteria - Chlamydia trhichomatis. Most common cause of bacterial STI, leading cause of infertility, blindness worldwide. Elementary body (infectious form) and Reticulate body (active form to create new EB). Chlamydia ABC - Trachoma - chronic keratoconjunctivitis leading to blindness. Chlamydia D-K - urogenital inf. & inclusion conjunctivitis.
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Tests for Chlamydial lymphogranuloma venereum..
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Frei test, monoclonal Ab test, Tissue culture.
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Features of Chlamydial lymphogranuloma venereum.
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Caused by serotypes L1, 2, 3. Sometimes confused with syphilis, herpes, chancroid. Main affects lymphoid tissue with initial manifestation as swelling of inguinal lymph nodes
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Features of Rickettsial infections.
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Most are vector borne except for Q fever.
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Diseases of Ricketssial infections.
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Q fever (aerosols), Rocky Mountain and Spotted Fever (dog ticks), Epidemic typhus (body lice), Scrub typhus (mites/chiggers)
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Features of Typhus fever.
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Small vessel lesions and areas of hemorrhage and inflammation. Cuff of mononuclear inflammatory cells around affected vessel.
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Features of Rocky Mountain Spotted Fever (RMSF)
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Hallmark is hemorrhagic rash over entire body. Major cause of death is noncardiogenic pulmonary edema causing adult respiratory distress syndrome.
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