Download Microbiology bio 123

Module C-14
Circular and Nervous Systems
Nervous System:
Structures:
Brain
Spinal cord
Peripheral Nervous System
Flora:
No normal flora - sterile
Bacterial diseases:
Meningitis
a. Inflammation of the meninges, membranes that cover the brain and spinal cord (keeps the CSF fluid
inside them)
b. Can be caused by any organism that can penetrate or pass the CSF barrier
c. The most severe meningitis is bacterial, and also the most common:
1. Meningococcal meningitis
a. Caused by Neisseria meningitidis (same family as gonorrhea) gram negative diplococcus
b. Referred to as “The meningococcus”
c. Predisposing conditions:
- When you have a great mixture of cultures, (people from around the world), increases
the risk of an asymptomatic carrier
- A lot of people living in close proximity
- A lot of people that are under chronic stress
d. Rapid onset. Can be fatal in 24 hrs - must be treated ASAP.
e. Transmission:
- Droplets from infected person
f. People who recover often have permanent disabilities
g. Symptoms:
- Begins with flu-like symptoms – fever, aches
- Progresses to neck and spinal (nuchal) rigidity
- Body rash (due to development of petechiae)
h. Incubation period of 1-7 days
i. Treatment is with Ceftriaxone or Chloramphenicol (crosses blood-brain barrier).
j. People who come in contact with the patient will receive Rifampin as a prophylactic
treatment and also be vaccinated.
k. Vaccine available
2. Hemophilus influenza
a. Gram negative bacillus
b.
c.
d.
e.
f.
g.
h.
Also a form of meningitis that can cause otitis media and pneumonia
Is the most common cause of meningitis in ages 3-5 years
Type B is the most commonly seen
Vaccine is HiB, Hemophilus influenza B vaccine
Symptoms are the same except for no rash (stiff neck, fever, etc.)
Not as harsh as the Neisseria meningitis
Treatments are Chloramphenicol and Ampicillin
3. Viral meningitis
a. Referred to as “aseptic meningitis”
b. The most mild meningitis
c. Flu-like symptoms
d. Caused by enterovirus – enters through intestinal tract and targets other areas of body
e. Transmitted by fecal-oral route
f. Disease is self limiting
Hansen's disease (leprosy)
a. Caused by Mycobacterium leprae
b. Same family as tuberculosis
c. Waxy cell wall - cannot gram stain. Acid fast bacilli. Grown on foot pads of mice or surface of
armadillos
d. Very resistant to drying
e. Organism multiplies in Schwann cells, the cells that form the myelin around the axons (referred to as
the myelin sheath.) Destroys the myelin sheath.
f. The type of nerve cells that are affective and the sensory neurons of the skin (peripheral nervous
system). Results in loss of sensation.
g. Transmitted possibly by contact with the skin lesions, but not sure
h. Bacteria does not culture
i. Incubation period is from 3 months to 20 years
- Cell doubling rate is in days (reference E. coli takes about 15 min.)
j. Two forms of leprosy
a. Tuberculoid form
- Milder than the lepromatous form
- Localized edema and swelling of the extremities, resulting in damage of skin and mucus
membranes
b. Lepromatous form
- Tuberculoid form can move into the lepromatous
- Involves the whole skin. Can cause bone deformities in cooler parts of body.
- Chemotaxis calls in osteoclasts which dissolve and reabsorb bone.
- Blindness, skin lesions, etc.
k. Most common in countries that are in the vicinity of the equator and in countries that have poor
nutrition
l. Treatments include Dapsone and Rifampin. Can treat but cannot restore injured tissue.
m. When starting treatments, will be not contagious after 3-6 months
n. If lepromatous form, will need maintenance dose for life. Progression arrested after 1 year.
o. If tuberculoid form, will need maintenance dose for life. Progression arrested after 6 months.
Tetanus
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
o.
p.
Clostridium tetani
Obligate anaerobe. Gram positive bacilli. Produces exotoxins (tetanospasmin)
Likes soil with feces in it
Protectors: intact skin and vaccinations
Can survive in spore form
Multiplies in deep wounds that contain anaerobic conditions
Produces exotoxins which cause tetanospasm
Exotoxins causes the continuous release of acetylcholine which results in prolonged contraction of
voluntary muscle
Uncontrolled release of acetylcholine from nerve cells causes rigid paralysis
Masseter muscle first to be effected, called “lockjaw”
If untreated, spreads to other skeletal muscles, then involuntary muscles
Incubation period of 3 days-3 weeks (usually 1 week)
Early Stages
- Patient is very sensitive to stimuli such as bright light and noise. Triggers may cause the
muscle contractions which are unable to relax. Keep patient away from stimuli.
- Need to protect pt against toxins
Late stage
- Classic late sign is body being bent over backwards from muscle contractions
- Broken ribs due to intense force of back muscles contracting
Treatments
- Neutralize toxins with antitoxin
- Immunizations with tetanus toxoid
Increased risk:
- Breaks in skin
- Circumcision
- Abortions
- Tattoos
- Spider bites
- Injections
Viral diseases of the nervous system
Rabies
a.
b.
c.
d.
e.
f.
g.
Rhabdovirus - bullet shaped neurovirus
Slow progressive zoonotic (crosses species lines)
Causes meningoencephalitis - inflammation of meninges, spine, and brain
Carried in saliva of infected species
Transmitted through the bite from infected animal, through mucus membrane, or any opening in skin.
Virus will multiply in bite for 1 wk before spreading to nerve trunks and traveling to the brain
Virus does not travel in the blood, but in the nerves
h. Incubation period is dependent upon the distance from the brain where the bite is
i. 100% FATAL once clinical signs are showing
j. Early symptoms - begins with prodromal (generalized) symptoms:
- Chest pains
- Headache
- Fever
- Nausea and vomiting
- Fatigue
k. Later (clinical) symptoms include:
- Visual disturbances
- Slurred speech
- Twitching
l. Two forms of rabies:
1. Furious:
- Frothing at the mouth (because of the lack of ability to swallow)
- Aggressiveness
- Seizures
- Twitching
2. Dumb:
- Dazed
- Disoriented
- Last paralysis
m. Positive diagnosis is from Negri bodies in the brain tissue (may not be able to see until after death)
n. Treatments:
a. If bitten:
- Live domestic animal - quarantined for 10 days
- Dead domestic animal - the brain is examined for Negri bodies
- Wild animal will be killed if possible to check brain for Negri bodies
b. Care of bite:
- Wash wound thoroughly and deeply with soap and water.
o. Vaccination:
- Series of 5 shots given over one month, typically given in the arm
- Ok to vaccinate after exposure due to long incubation period
p. Has also been spread by cornea transplants, inhalation of bat feces
q. Common carriers are skunks, raccoons, and bats
Encephalitis
a. Inflammation of the neurons in the brain
b. NSF is sterile so anything that is in NSF fluid can cause encephalitis
c.
d.
e.
f.
Common causes are arthropod borne illnesses
Cannot be communicated to others
Can only treat symptoms because it’s viral (RNA virus)
Symptoms:
- Fever
- Lethargy
- Visual disturbances
- Convulsions
- Coma
- Death
g. Possible outcomes:
- Complete recovery (most healthy adults do)
- Permanent paralysis
- Death
h. St. Louis and West Nile strains are most common
- Requires reservoir, vector, and host
- Birds = reservoir, Culex mosquito = vector, human = host
- Can survive in domestic birds
b. Avoid standing water - breeding ground for mosquitoes
c. Young and elderly are at high risk because of decreased immune system.
Poliomyelitis
a.
b.
c.
d.
e.
Effects the motor neurons (neurovirus)
These individuals can feel everything, but cannot move. Called a flaccid paralysis.
Due to phenomenal vaccination policies, we rarely see polio today.
Transmitted by fecal/oral route, commonly by contaminated water.
Salk vaccination - was a killed vaccine in a series of three shots because of the three main
strains of poliomyelitis.
f. Sabin vaccination - the oral polio vaccine, called TOPV (Trivalent Oral Polio Vaccine – all
three strains in one shot). This is not a killed virus, only attenuated.
g. Collateral nerves take over the functions of the damaged motor nerves in post polio syndrome
and have many varied symptoms of polio.
h. In the past, “Iron Lungs” assisted breathing in polio patients through changes in pressure.
Circulatory System:
Structures:
Heart
Lymph
Blood vessels
Blood
Flora:
Sterile – no normal flora
Bacterial infections
Septicemia
a.
b.
c.
d.
e.
Bacteremia
Microorganisms or their products circulating in the bloodstream
Almost always results from an infection somewhere else in the body, in a wound, etc.
Localized and then spreads
Symptoms:
- Chills
- Fever
- Shaking
- Nervousness
- Rapid breathing
f. If due to a Gram negative, when it releases the endotoxin, there is a massive increase of
symptoms. It will cause a system-wide immune response (endotoxic shock) and is the most
rapid.
g. Treatments are treating the microbe and with treating for shock
- Antibacterial
- Antiparasitic
h. Fatality rate of about 50%
Plague
a.
b.
c.
d.
e.
f.
g.
h.
i.
Bubonic plague, “Black Death”
Is a zoonosis (crosses species lines)
Yersinia pestis
Gram negative
Does not form spores, but when gram stained, the ends will stain, and the center will stay
clear
Transmitted by the bite of an infected flea, specifically a rat flea. Typically a rodent-vectorhost
Incubation period of 1-6 days after the bite
Symptoms:
- Fever
- Shock
- Bleeding under the skin (reason for the name black death)
- Enlarged lymph nodes (called bubo)
- Bloody cough and sputum
This disease is endemic in rats
j. Can progress to the disseminated form (respiratory) and travel to the lungs where it is called
the pneumonic plague (faster and more deadly. Can be acquired via inhalation). This causes
an increase in mortality rate of 50% for bubonic, 90% for pneumonic, if untreated.
k. Treatments streptomycin or tetracycline
l. No vaccine exists
m. Pneumonic – could be inhaled so could be a bioterrorism threat
Tularemia
a.
b.
c.
d.
e.
f.
g.
n.
o.
p.
Also a zoonosis
Francisella tularensis
Gram negative bacillus
Transmitted through bites of fleas and ticks or through skinning wild animals, such as deer
and rabbits
Incubation period of 2-5 days after the bite
Vaccination does exist for those at high risk
Symptoms:
- Fever
- Chills
- Aches
- Skin ulcers
- Enlarged lymph nodes
- Key symptom is night sweats
- Chest discomfort and dry cough
Is one of the most infectious organisms, requires the least amount of the organism – easily
transmitted.
Treatment is with tetracycline
Pneumonic – could be inhaled so could be a bioterrorism threat
Lyme disease
a.
b.
c.
d.
e.
f.
Zoonosis
Borrelia burgdorferi
Spirochete, corkscrew shaped.
Most commonly reported tick-borne disease
In order to clear body, it must be treated early.
Symptoms:
- Chills
- Fever
- Headache
- Aches and pains
- Nuchal rigidity
g. Three stages:
1. First stage:
- Development of expanding bulls-eye rash (not everyone develops rash)
- Chills
- Fever
- Stiff neck
- Aches
2. Second stage:
- 2-8 Weeks
- Heart rhythm
- Nervous system effects:
Facial paralysis
Moodiness
Paralysis of arms and legs
3. Third stage:
- 6 months after rash
- Arthritis
- Joint pain, swelling, and tenderness
- Symptoms are immune-response related
h. Treatments is with Doxycycline
i. Immunization exists and is three part (not routinely given)
Rocky Mountain Spotted Fever
a.
b.
c.
d.
e.
f.
Reckettsia rickettsiae
Gram negative coccobacillus
Zoonosis
Reservoir is wild animals, mostly mammal
Vector is a tick
Symptoms:
- Severe backache
- Fever of 105-106
- Severe headache
- Rash that begins on the wrist and ankles and spreads from there
g. Treatments broad spectrum antibiotics
h. Most common between the Appalachians and the Midwest
Typhus
a. Two forms that belong to Reckettsia species (both cause same symptoms)
1. Reckettsia typhi
2. Reckettsia prowazecki
b. Difference is the mode of transmission
c. Symptoms of typhus:
- Acute fever
- Headache
- Hemorrhage
- Muscle pain
- Rash that begins on trunk and then spreads to the rest of the body
d. R. typhi causes endemic typhus (endemic in rats)
- Reservoir = rats; vector = flea; host = human
e. R. prowazecki causes epidemic typhus
- Starts with human, and then is transmitted to the louse through bite and then
transmitted to another human through flea bite
- Reservoir = humans; vector = body louse; host = human
Viral and protozoan infections of the circulatory system
Infectious Mononucleosis
a.
b.
c.
d.
e.
f.
g.
h.
Belongs to the herpes virus family
Can recur due to latency
Epstein-Barr virus; EBV
Transmitted through body secretion - specifically saliva
Also called “kissing disease”
Incubation 2-6 weeks or longer
Severity varies
Symptoms:
- Sore throat
- Low fever
- Swollen lymph nodes
- Intense fatigue
- Possible jaundice (liver function)
i. 90-95% of adults are infected
j. Not very easy to infect, requires prolonged contact
k. No vaccination and no treatment exist because it’s viral. Treat symptoms and rest.
Malaria
a.
b.
c.
d.
e.
Protozoan
Plasmodium species - multiple
Two most common species are virax and falciparum
Vector is the Anopheles mosquito
Malarial attacks are precluded by the rupture of the RBCs, releasing large amounts of
virus
f. Treatments are with quinine products such as Chloroquine
g. Symptoms:
- High fever
- Chills
- Drenching sweats
- Headache
- Poops
- Vomiting
- Cough