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Micro. Chapter 19, Nervous System Diseases. Micro. Chapter 19, Nervous System Diseases. 1. Meningitis – Neisseria meningitidis – Gram (-) diplococci (related to GC species) pg 580 A. Virulence factors: i. Capsule and pili ii. Iga proteases – enzymes that break down
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Micro. Chapter 19, Nervous System Diseases 1. Meningitis – Neisseria meningitidis – Gram (-) diplococci (related to GC species) pg 580 A. Virulence factors: i. Capsule and pili ii. Iga proteases – enzymes that break down antibody, Iga antibodies are secretory antibodies on mucus membranes iii. Iron binding enzyme – can get to and use bodies iron iv. Endotoxin producing strains are really virulent, strain b and c are the virulent ones, strain c is the one at UT recently
Micro. Chapter 19, Nervous System Diseases B. Mode of transmission – respiratory droplets, type b and c are highly infectious C. Symptoms – fever, stiff neck and headache, sometimes a rash – not too alarming at first, but can rapidly progress to convulsions and coma D. Rapid diagnosis is essential, so antibiotic can be given before CNS damage is too severe – penicillin and penicillin family antibiotics, rifampin given in prophylaxis (when there is exposure as in a dormitory or barracks) E. Vaccine is available, not that effective especially with children F. Meningitis can be caused by viruses (echovirus – tends to be mild), other bacteria (such as Strep, Haemophilus, Listeria), fungi, even protozoans)
Micro. Chapter 19, Nervous System Diseases G. Listeria monocytogenes – see page 582, Checkpoint 19.1 resistant organism to normal environmental properties, in elderly, very young, and immunocompromised serious to fatal disease, in LA county in the 70’s serious outbreak in pregnant women and transfer to fetus is possible (ingesting contaminated dairy products – Mexican goat cheese)
Micro. Chapter 19, Nervous System Diseases 2. Botulism – (pg 603) Clostridum botulinum - Gram+ anaerobic spore forming bacillus, soil microbe A. A form of food poisoning – intoxication, produces the most potent of natural toxins B. Exotoxin that is produced by the bacteria in an anaerobic condition like in canned goods C. Toxin effects the CNS, interferes with nerve transmission at neuron junctions D. Toxin is heat labile (destroyed by heat)
Micro. Chapter 19, Nervous System Diseases E. 3 types of disease 1. Preformed toxin in food – can goods A. Type a C. bot toxin can kill with just a taste B. Other types are bad too 2. Infant botulism A. Floppy baby syndrome – neck is real flaccid- ?? Spores ingested and they grow in the digestive tract and slow absorption of toxin causes symptoms (raw honey) B. C bot grows in gut but in adults it is normal flora and not harmful 3. Wound botulism – rare infections of wound (like C. perfringens) F. Treatment – adults – antitoxin, babies, supportive therapy and antibiotics (?) G. Prevention – properly handling canned goods, never taste from a dented swollen can
Micro. Chapter 19, Nervous System Diseases 3. Bacterial tetanus – Clostridum tetani bacteria is also Gram+, anaerobe, endospore forming soil organism (Pg 596 -597) A. Powerful exotoxin that is a neurotoxin – interferes with signals for muscular contraction and relaxation B. Muscles stay contracted (tetanus) C. Soil contamination of deep wounds D. Treated with Immunoglobulin (antitoxin) E. Good vaccine – toxoid (dpt)
Micro. Chapter 19, Nervous System Diseases Viral diseases of the nervous system 1. Rabies – rabies virus is a rhabdovirus: rna virus, bullet shaped and has an envelope see page 596 A. Fatal encephalitis B. Acquired by an animal bite or handling an infected animal C. Coyotes ,skunks, raccoons, bats (and others) different strains D. Type of infection with rabies: virus has an affinity for nervous tissue, spreads from site of bite to nervous tissue. Very slow progression toward the CNS. 2. Rationale for post exposure rabies treatment – active and passive immunity a. Injection of immunoglobulin at site of bite and then in the muscle b. Injection of rabies vaccine – develop strong immunity before the virus can travel to the CNS and cause disastrous nervous tissue damage. c. Human diploid cell vaccine or chick embryo grown virus vaccine. d. 5 to 6 injections over 4 weeks (Im shot) (average cost was about $1200 for a post exposure treatment here in Austin)
Micro. Chapter 19, Nervous System Diseases 3. Animal workers are now offered pre-exposure rabies vaccination- inter dermal or im 4. Prevention – vaccination of domestic pets, newer wild animal vaccine programs (coyotes and foxes in Texas), avoid any sick or injured animals – skunks active in daytime, downed bats, etc.
Micro. Chapter 19, Nervous System Diseases 2. Polio viral infection – caused by small non-enveloped virus (naked) called a Picorna virus A. Enterovirus – acquired by contaminated food or water, fomites, and mechanical vectors too B. Disease is usually limited to the throat, tonsils, and lymph nodes, but it can infect the nerve tissues, especially motor neurons of the spinal chord, leading to paralysis or even death C. Treatment is usually supportive therapy D. Prevention – vaccine a. Salk vaccine – inactivated viral vaccine, trivalent (3 strains) b. Sabin is live attenuated virus c. Salk for infants and Sabin for later, infant immune system not as developed and there is some potential for the attenuated virus to become infective d. WHO is till working on polio and measels to eradicate them
Micro. Chapter 19, Nervous System Diseases Polio – iron lung; Jonas Salk
Micro. Chapter 19, Nervous System Diseases Fungal infections: Cryptococcus neofrormans, causes meningitis, it is yeast with a very large capsule (we will save C. immitis to resp. diseases) 1. Mode of transmission, airborne from soil or bird droppings (pigeons) 2. Slow developing meningitis, travels from lungs to blood stream to nervous system 3. Diagnosis – presence of yeast and capsule in csf 4. Treatment – amphoteracin b Infection is uncommon but is very difficult to treat 5. now have a good Ag test used on CSF
Micro. Chapter 19, Nervous System Diseases Arboviruses 1. Arthropod borne viruses – general term for many unrelated viruses transmitted by arthropods 2. There are at least 5 major encephalitis viruses in the us 3. Wee, EEE, SLE, VEE, CEE, and now here in Texas WNV 4. Transmitted by mosquito bite, and horses and birds are the reservoir 5. High fever and horrible headache, sometimes paralysis 6. Eliminate vector mosquito (spray and eliminate standing water)
Micro. Chapter 19, Nervous System Diseases ARBOVIRUSES
Micro. Chapter 19, Nervous System Diseases Protozoans – Trypanosomes, will cover in lab, reservoir is in wild game animals, and the vector is the Tsetse fly – African sleeping sickness PAM : recently seen in the Hill country, stagnant water with bird fecal matter
Micro. Chapter 19, Nervous System Diseases Prions – infectious proteins – Kuru- cannibalistic rituals in new guinea CJ – Creutzfeldt-Jakob of humans Mad cow disease in cattle – bovine spongiform encephalopathy 1. Very slow progressive disease that may attack proteins in CNS 2. Damage to brain gives brain tissue a spongy appearance – encephalopathy – very scary Video: “The Brain Eaters”
