Transcript Micro. Chapter 19, Nervous System Diseases

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
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
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
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
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
Micro. Chapter 19, Nervous System Diseases
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
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
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
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
Micro. Chapter 19, Nervous System Diseases
PAM
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”
Micro. Chapter 19, Nervous System Diseases