Microbiology ch. 22 microbial diseases of the nervous system
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16 terms
Terms | Definitions |
|---|---|
 Bacterial diseases of the nervous system | haemophilus influenza, neisseria mingitidis, streptococcus pneumonia, listeria moncytogenes, clostridium tetani, clostridium botulinum, mycobacterium leprae |
| Haemophilus influenzae | small aerobic, gram neg rod, normal biota of throat; main cause of meningitis in children under age 4 (2-7% all cases), vaccine preventable, capsule type b is the cause of most haemophilus (hib) disease vaccine. |
| Neisseria miningitidis | small aerobic, gram neg diplococcus, found in throat of carriers; begins as a flu-like illness, spreads to blood, then to meninges, symptoms similar to hib but has a rash that becomes large blue-black spots; capsule types a, b, c, vaccine available for c; spreads easily in close groups young adults (colleges, prisons, military), main cause of meningitis (15-40%) in young adults: test for meningitis—push head to chin and see if it hurts. Danger sign is bad headache. |
| Streptococcus pneumoniae | normal flora of the throat, gram pos, cause of earaches and meningitis in young children and 500,000 cases of pneumonia in the elderly, maybe really 1-1.5 million, antibiotic resistance is high but it is vaccine preventable. |
| Listeria monocytogenes | small gram-pos rod found in soil, water, processed meat and dairy products; can cause meningitis and death in the fetus (60% mortality), rarely fatal in adults; can grow in phagocytic cells and at cold temperatures. |
| Clostridium tetani | anaerobic spore-forming gram pos rod found in the soil; symptoms caused by the toxin "tetanospasmin", 2nd most powerful bacterial toxin, acts on nerve-muscle synapse by preventing breakdown of "acetylcholine" so that muscles continue to contract; death results from seizure of respiratory muscles, it is vaccine preventable. |
| Clostridium botulinum | anaerobic spore-forming gram pos rod found in the soil; contracted by eating infected food, symptoms caused by the most powerful bacterial toxin, inhibits release of acetylcholine so that no nerve impulses reach the muscles, results in "flaccid paralysis," death caused by respiratory and cardiac failure; several toxin serologic types: type a causes most severe disease with 60-70% mortality, type b is less severe with 25% mortality, type e is associated with seafood and has 40% mortality; infant botulism occurs by feeding babies honey contaminated with spores. |
| Mycobacterium leprae | acid fast bacillus, grows in peripheral nerves and skin cells at 30 c, 12 day generation time, incubation time can be 3 to 6 years, does not grow in lab media but can grow in mouse foot pads and in armadillo; |
| two forms of mycobacterium leprae | (1) tuberculoid form occurs in people with effective immune system, causes regions of skin to lack sensation, recovery may be spontaneous; (2) lepromatous (progressive) form occurs in people with less effective cellmediated immunity, skin cells are infected and disfiguring nodules form over the body; spread by nasal secretions. |
| Viral diseases | polio, rabies, arboviral excephalitis |
| Poliomyelitis | RNA virus is very stable, ingested in contaminated water, generally mild or asymptomatic disease but can infect the CNS and cause paralysis, death results from respiratory failure; Salk vaccine uses viruses killed with formalin, Sabin vaccine (oral polio virus) uses three living attenuated virus strains, disease has been eliminated in Americas and Europe. |
| Rabies | spread by bite of infected animal, 30 to 50 day incubation period, grows in muscles then travels up the peripheral nerves to the CNS, symptoms result from loss of nerve control, usually fatal in a few days, can be spread by aerosols; treatment is by vaccine and immune globulin injections: bats in cave. |
| Arboviral encephalitis | spread by mosquitoes in birds, can be a disease of horses and sometimes humans; causes inflamation of the brain, symptoms are chills, fever, headache, coma and death; generally a mild disease. |
| Fungal | cryptococcus neoformans, a yeast with a thick capsule, found in soil containing bird droppings, spread by inhalation of infected dust; usually mild infection of lungs, can spread to blood and then to brain. |
| Protozoans | Trypanosomiasis (african sleeping sickness), spread by bite of tsetse fly, Trypanosome grows in blood and spreads to cerebral spinal fluid; physical and mental activity decreases ending in coma and death within 2 to 4 years, treated with drugs, vaccine not effective; Primary amoebic meningoencephalitis, rare disease spread by protozoa (naegleria fowleri), found in recreational fresh water, infects mostly children thru nasal mucosa, penetrates to brain, 100% death. |
| Prions | fatal disease of the CNS, caused by self-replicating protein, spread by contact with or ingesting infected tissues. |
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