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Pathogenic Final
Pathogenic Bacteriology final exam flash cards
| Question | Answer |
|---|---|
| What should be added to the broth to allow Mycobacterium Tuberculosis to grow better. | Growth is better in broth medium with Tween80 (surfactant) [40% of cell dry wt = waxy lipid cell wall] |
| What media does mycobacterium grow best on. | Grown on media with egg, egg yolk, glycerol, potatoe and malachite green to suppress normal flora. |
| What do virulent strains of Mycobacterium tuberculosis have? | Virulent strains have "cord Factor" and produce serpintine cords. |
| What are the predisposing conditions of mycobacterium? | malnutrition, alcoholism, diabetes, dramatic change in life style. |
| What is the most common route of infection for mycobacterium? | Mostly respiratory tract (droplet nuclei = 5micrometers diameter) |
| what is a granuloma (tubercle) ? | center undergoes caseation necrosis- macrophages surrounded by lymphocytes and fibroblasts, epithelioid cells and giant cells. |
| What changes may lesions of Mycobacterium tuberculosis undergo? What percentage heal? | Lesions may calcify, 90% heal. |
| When and where does reactivation of mycobacterium occur. | it is common in adults over 50yrs and usually occurs in the apex of the lungs. |
| What are the virulence factors of Mycobacterium Tuberculosis? | 1. Cord factor - blocks degranulation in phagocytes 2. Sulfatides - inhibits intracellular superoxide radical production. 3. Arabinogalactan & lipoarabinomannan - strong antibody response - necrosis and granuloma. 4 tuberculoproteins-cell immmune respo |
| What are symptoms of Mycobacterium tuberculosis? | chronic fever, weight loss, night sweats, productive coughing, hemoptysis |
| how must sputum of Mycobacterium be treated before it is cultured? | sputum is digested with 1% hypochlorite, NaOH or N-acetyl-cysteine. It is then cultured on Lowenstein- jensen or Petragnani slants. |
| While not common, where would you expect to find Mycobacterium avium-intracellulare infections? | While slow growers, they can be found in disseminated infections in AIDS patients, spread laterally and occasionally pulmonary in immunocompetent individuals as a secondary invader. High resistant to antibiotics. |
| What is the pathogenesis of Mycobacterium leprae? | Tuberculoid - limited to superficial nerve endings and related skin area (produces a flat lesion) Lepromatous (nodular) - granulmatous tissue called lepromas cause distortion and mutilation. |
| How long does leprosy take to incubate? What is its generation time? What is unique about this generation time? | It may take as long as 30yrs to incubate but averages 2-5 yrs. Generation time is 11-13 days, the slowest growing human pathogen. |
| What is the treatment for leprosy? | Dapsone or thiosemicarbazone, 3-5 months to several years or forever. |
| What are the three biotypes of C. Diptheria? | Gravis - rough large colonies Mitis - smooth smaller colonies intermedius -smallest colonies |
| What is the human lethal dose of C. Dip toxin? where is the toxin coded for? | human lethal dose is 100ng Coded for by Beta-phage |
| What are the conditions for maximal production of C. Dip toxin? | pH 7.8-8.0, maximum aeration and proper iron concentration ( opt. 140 ng/ml) |
| What is the mechanism of action of the C.dip toxin? | Inhibits protein synthesis by splitting NAD and transfering ADP-ribose to EF-tu and halting peptide elongation. |
| Where does the C.dip toxin bind? Does the toxin need to be nicked? | Toxin binds to cellular glycoprotein. Must be nicked. |
| What are the sysmptoms of C. dip? | fever, chills, sore throat, serosanguinous nasal discharge, enlarged cervical lymphnodes, and a "pseudomembrane usually in the throat, sometimes on tonsils. |
| How is C. dip diagnosed? | Swab the nares or pharynx and plate on Loeffler's medium, tellurite agar or BAP. Stain for metachromatic granuels and perform toxicity test |
| What immunity is there for C. Dip toxin? | antitoxin activity is against b subunit. 5 injections of formalin or alum treated toxoid. |
| What is the treatment for C. Dip | antitoxin and penicillin or erythromycin |
| Where are cases of L. Monocytogenes most common? | most common in neonates and immunocompromised |
| What is odd about the culture L. Monocytogenes will grow on? | will grow up to pH 9.6 and in high salt conc. (6%) Also ferments acid, kills in 2 days. |
| What are the 3 effects of toxin produced by L. Monocytogenes? | 1.Monocytosis caused by a lipid in the cell wall. 2.Oxygen Labile hemolysin(cardiotoxic) Listeriolysin- lyse phagosomla membrane - cause actin polymerization- spread intracellularly. 3. Protein- cytotoxic for mouse peritoneal macrophages and lipolytic. |
| What diseases does L. Monocytogenes cause? | Disease may involve CNS, encephalitis, encephalomyelitis, and may involve reproductive tract = abortions. Effects upper respiratory tract, regional lymph nodes, conjunctivitis. |
| How is L. Monocytogenes treated? | Treatment is tetracyclines, erythromycin, bactrim. |
| Where are organisms of L. Monocytogenes isolated from? | Blood, bone marrow, sternal puncture, mucous membranes, spinal fluid. |
| What are the 5 things similar between all Spirochaetes? | 1. Intermediate between protozoa and true bacteria 2. flexuous cell wall 3. all motile- function of cell wall 4. in-vitro cultivation +/- possible 5 Central axial filament(s) + helical cylinder of cytoplasm. |
| What antigen do all spirochaetes share? What are they all sensitive to? | Share Reiter's Antigen. Sensitive to heavy metals (Bismuth, antimony, mercury) and penicillin. |
| How are Treponema pallidum cultured? | cultivated on the skin or in the scrotum of a rabbit. (microaerophillic) |
| What are Treponema pallidum coated with to help them bind to epithelial cells? | Fibronectin. |
| What are the virulence factors of Treponema pallidum? | 1. mucopolysaccharide capsule- protects against O2-toxicity and against antibodies against outer membrane. 2. mucopolysaccharidase - receptor mediating adherence to host cells by interaction with hyaluronic acid. 3. Infectious dose = 57 organisms. |
| What is primary stage syphilis? | A Lesion 90% time on cervix, penis, anus, lips. Painless papule that develops into an ulcerated sore = "hard chancre" 10-90day incubation (21avg) lasts 1-3 months patient has enlarged lymph nodes. |
| What is secondary stage syphilis? | (4 weeks - several months) 1 in 4 chance from primary syphilis. Cutaneous and mucus membrane esions, hair loss, skin rash on trunk and limbs. alll lesions have spirochaetes. Both primary and secondary syphilis are highly contagious. |
| What is LAtent syphilis? | High antibody titer and no symptoms |
| What is tertiary syphilis? | 1 in 2. 3-30yrs later, non-infectious. 1.Gummas- typical lesions. On bones: periosteitis(proliferation of bone under periosteum) osteitis(bone deformation) 2. Cardivascular lesions- death 3. CNS lesions: loss of control, general paralysis of insane. |
| What is congenital syphilis? | Mothers with primary/secondary syphilis after the 16th week of pregnancy will infect fetus(untreated- 25-50% stillborn, 25% die soon after) 50% of survivors have severe infections. |
| What are the symptoms of Relapsing fever? | 3-4 days of chills+fever, headache, muscular and joint pain, tender spleen and jaundice. Fever reappears in 4-14 days, may have as many as 10 cycles, usually 1-5. Surface antigens change to cause relapses. |
| How is Leptospirosis visibly identifiable from other spirochaetes? | They have a hook at one or both ends of the spirochaete. |
| How is Leptospirosis cultivated? | Cultivated in peptone-beef extract w. 10% rabbit serum. Obligate aerobes, 30 C optimal temp. |
| What are the symptoms of Leptospira infection? | High fever, nausea, vomiting, headache, pains, bronchitis, jaundice. 6-12day incubation. Bacteria centralize in liver, kidneys, lungs, meninges. |
| Who is at risk for Leptospirosis? What is its natural reservoir? | Humans are contaminated by ingestion or through abraded skin. Hazard for farmers, miners, dock worker. Reservoir- rats, dogs, pigs cattle. |
| What disease is caused by Borrelia Burgdorferi? What are its reservoirs and vector? | Causes Lyme disease. Reservoir is the white-footed mouse and secondarily Deer. Vector is the tick Ixodes scapularis. |
| What are the symptoms of Lyme disease? | Bulls-eye rash, flu like symptoms, may go to meningitis, arthritis. Extreme fatigue. |
| What is characteristic about Mycoplasmas? | They are filterable- have no cell wall(no peptidoglycan) and contain cholestrol in their cell membrane. |
| What disease does M.mycoides cause? | causes bovine pleuropneumonia. |
| What selective agents are added to the medium to select for Mycobacterium growth? | Penicillin (they have no cell wall) and Thallium acetate. Colonies will have a "fried-egg" appearance. |
Created by:
Lord Azith
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