Microbial Diseases of the Nervous System

Flashcards related to microbial diseases of the nervous system

Central Nervous System

The brain and spinal cord

Peripheral Nervous System

Cranial and spinal nerves

Blood Brain Barrier

Keeps toxins in blood from brain, capillaries wrapped by astrocytes, allows passage of lipid soluble substances

Encephalitis

Inflammation of the brain

Meningitis

Inflammation of meninges in brain

Meningitis Symptoms

Fever, headache, stiff neck, nausea, vomiting, convulsions, coma

Viral milder (meningitis)

Can be treated

Enterovirus (meningitis)

Attack guts, form of meningitis virus

Measles, mumps, influenza (meningitis)

Measles are the 1st infection

Historical Causes of Meningitis

Streptococcus pneumoniae, Haemophilus influenza, Neisseria meningitidis

Virulence Factors in Meningitis

Capsules and can replicate in the blood, travel to CNS

Haemophilus influenza type B (Hib)

Once most common, now nearly eliminated due to vaccine.

Neisseria meningititidis & Streptococcus pneumonia

80% of all cases 16+ years

Vaccines for S. pneumoniae

Has created herd immunity with 70% of the population as carriers

N. meningititidis

Without treatment it has an 80% mortality rate. 40% of the population acts as a reservoir carrying the bacteria in the throat.

Meningitis treatment

Develops quickly so broad spectrum of antibiotics are administered - usually cephalosporin. Once organism is identified, antibiotic treatment may change

Listeria monocytogenes

G+ rod, found in soil/water contaminated with animal feces. Mild in adults but can cause meningitis

Listeria monocytogenes virulence

Crosses placenta, causes still births. Grows in refrigerator temperatures. Transmission is food borne

Bacteriophage spray

Approved by the FDA as a spray preservative for deli meats

Antibiotic of choice for Listeria

Penicillin G

Clostridium tetani

G+, obligate anaerobe, spore forming rod. Tetanospasmin neurotoxin - toxin released from cell

Clostridium tetani infection

Bacteria do not spread, no inflammation

Lockjaw

First sign of Clostridium tetani infection, muscle contracts, not able to relax

Cause of death in Clostridium tetani infection

Spasms of respiratory system

DTaP

Diphtheria Tetanus acellular pertussis, a toxoid vaccine

Tetanus Immune Globulin (TIG)

Given formed antibodies

Debridement

Cut/remove necrotic tissue

Clostridium botulinum

Produces exotoxins in anaerobic environments. Blocks the release of ACh - flaccid paralysis

Clostridium botulinum infection

Death from respiratory or cardiac failure

Clostridium botulinum toxin

Toxin can be destroyed with heat, will not grow in acidic environments unless mold is present

Drugs of choice for Clostridium botulinum infection

Streptomycin and rifampin

Muktuk

Sliced flippers of seals and whales, tenderized in anaerobic jar until putrefaction, common among native Alaskans

Infant botulism

No honey for kids until 1 year old

Treatment for Botulism

Recovery slow, allowing time for nerve regeneration and may require respiratory therapy

Mycobacterium leprae & M. lepromatosis

Grows best at 30 degrees - periphery of body. Invades myelin sheaths of PNS

Generation time of M. leprae

12 days to go from 1 bacterium to 2

Culturing M. leprae

Will not grow on artificial medium - armadillos

Tuberculoid form of M. leprae

Creates lesions in skin, appear as light areas, loose sensation

Lepromatous form of M. leprae

Skin cells are affected causes formation of nodules, can cause destruction of peripheral body areas

Drugs of choice for M. leprae

Sulfone drugs and rifampin

Polio

Most asymptomatic or mild flu like, fecal oral transmission

Pathogenesis of Polio

Multiplies in the throat and small intestine - viremia - Blood - may enter the CNS

Polio Immunity

Antibodies cross the placenta - giving fetus natural protection

Polio Vaccine

Attenuated viruses

Rabies

Causes fatal encephalitis

Genetic Material of Rabies

SS RNA without proofreading abilities mutates

Transmission of Rabies

Saliva in bites but can be transmitted by skin abrasions, or cross mucous membranes

Pathogenesis of Rabies

Proliferate – travels to CNS (brain spinal cord), can replicate in skeletal muscle

Immune Response to Rabies

Immune system does not respond because of small # of viral particles. Multiplies in skeletal muscle

Rabies Incubation & Treatment

Incubation 30 days up to 6 years, post-exposure prophylaxis one successful & chance of recovering

Symptoms of Rabies

Agitation, fear of water cause spasms in pharynx causes death of neurons

Encephalitis

Mosquito borne virus. Symptoms range from mild to severe chills/headache/fever --> confusion/coma/death

Equine Encephalitis

Horse form of encephalitis

Cryptococcis

Fungal meningitis

African Trypanosomiasis

Trypanosoma brucei organisms, bite blood to CNS coma. TSE TSE FLY

Bovine Spongioform Encephalopathy

Prion (Infectious protein) = endemic (lives) in sheep. Neurological.