INFECTIONS OF THE NERVOUS SYSTEM Flashcards
> Greek word “___________” which means “stretch.”
tetanos
Characteristics
- bacilli
- gram-positive
- Anaerobic
- spore-forming rods
- Spore is at one end (“terminal spore”)
- organism looks like tennis racket
Clostridium tetani
Habitat - soil
MOT - Organism enters through traumatic breaks in skin
I/P:- 4-5 days up to 3 wks
Clostridium tetani
> are the living organisms that live and feed on dead and decaying organisms
Saprophytes
damages viable tissue surrounding infection & optimizes cond. for bacterial multiplication.
Tetanolysin
- produces exotoxin,
- toxin blocks release of inhibitory neurotransmitters (glycine & γ-aminobutyric acid [GABA]) from spinal neurons.
- Excitatory neurons are unopposed & extreme muscle spasm (tetanus, spastic paralysis) results.
Pathogenesis
> Tetanus neurotoxin
released upon cell lysis after bacterial growth under anaerobic cond. (e.g., in deep puncture wounds)
prevents presynaptic release of inhibitory neurotransmitters glycine & gamma-aminobutyric acid (GABA).
Tetanospasmin (or tetanus toxin)
is a protease that cleaves proteins involved in the release of neurotransmitters.
Tetanus toxin (tetanospasmin)
w/ neurotoxin known as ____________..
Results to spastic paralysis
tetanospasmin
lockjaw
Trismus
sardonic smile
Risus sardonicus
Persistent back spasms
Opisthotonus
highly fatal disease characterized by muscle spasms & convulsions.
Due To:
TETANUS NEONATORUM
human globulin to neutralize toxin
tetanus immunoglobulin
> Bulges, dents near the ends of the can, a leak from anywhere in the can, a crack in the glass of the jar and RUST (for jars – rust on the margins of the lid) are reasons to toss out cans automatically
Clostridium botulinum
Characteristics
- bacillus
- gram-positive,
- Anaebrobic
- spore-forming
Habitat - soil
MOT - Organism & botulinum toxin transmitted in improperly preserved food.
Virulence Factors
- botulinum toxin
- 7 toxins ( types A to G)
- neurotoxic (affect nervous system - causes flaccid paralysis)
Clostridium botulinum
the chief neurotransmitter of parasympathetic nervous system, the part of autonomic nervous system ( branch of peripheral nervous system) that contracts smooth muscles, dilates bld vessels, increases bodily secretions, & slows heart rate.
Acetylcholine
- a protease (cleaves proteins involved in release of acetylcholine at myoneural junction), causing flaccid paralysis.
Botulinum toxin
Toxin inhibits acetylcholine release leading to _______________ (cannot contract muscles).
flaccid paralysis
- ingestion unpasteurized honey
- laccid paralysis (floppy baby)
- Can lead to sudden infant death syndrome(SIDS)
- > Death is due to resp paralysis
Infant – borne botulism
- descending, flaccid paralysis (can cause respiratory failure)
Classical Botulism
in which spores contaminate a wound, germinate, and produce toxin at the site
wound botulism
> “_____________,” which induces a cell-mediated response that limits its growth.
in “_____________,”, M. leprae multiplies at the site of entry, usually the skin, invading and colonizing Schwann cells. The microbe then induces T-helper lymphocytes, epithelioid cells, and giant cell infiltration of the skin, causing infected individuals to exhibit large flattened patches with raised and elevated red edges on their skin. T
tuberculoid (paucibacillary)
or Hansen’s Bacillus
Mycobacterium leprae
> creates an environment that is antagonistic to botulism. It’s what scientists call “competitive exclusion.” Beneficial bacteria begin to acidify the food, a condition C. botulinum doesn’t like. Adding salt to a ferment also reduces C. botulinum’s ability to grow, and encourages beneficial bacteria to take over. There are also other “competitive factors” that beneficial bacteria and fungi create in smaller quantities to exclude pathogenic varieties.
Fermenting foods
Which of the following food items is most frequently associated with infant botulism?
(A) Corn syrup
(B) Canned infant formula
(C) Liquid multivitamins
(D) Honey
(E) Jarred baby food
ANSWER IS “D”
affects the skin and peripheral nerves
hansen’s disease (leprosy)
> has the longest doubling time (at 13 days of doubling time in the mouse footpad.[12]) of all known bacteria and has thwarted every effort at culture in the laboratory
Also found in armadillos.
Mycobacterium leprae
- Aerobic, acid-fast rods.
- Cannot be cultured in vitro.
- Optimal growth at less than body temperature, so lesions are on cooler parts of body, such as skin, nose, & superficial nerves.
- Grows in peripheral nervous system
Mycobacterium leprae or Hansen’s Bacillus
more likely to transmit; higher numbers of organisms than tuberculoid
lepromatous form
2 forms of leprosy:
- Tuberculoid
- lepromatous
Nodular, multibacillary, patchy sensory loss, leonine face, clawed hands,saddle nose, (-) in lepromin test w/ strong antibody response
LEPROMATOUS (CUTANEOUS FORM)
- destructive lesions d/t cell-mediated response to organism.
Damaged fingers is d/t to burns & other trauma, bec. nerve damage causes loss of sensation.
tuberculoid leprosy
- cell-mediated response is lost; large numbers of organisms appear in lesions & bld. No toxins or virulence factors are known.
lepromatous leprosy
- delayed type of hypersensitive reaction
- first described by mitsuda in 1919
- used as antigens may be of human origin or armodillo derived
LEPROMIN TEST
(Etiologic Agents)
Neisseria meningitidis
Listeria monocytogenes
Mycobacterium Tuberculosis
ACUTE MENINGITIS (BACTERIAL)
(Etiologic Agents)
Cryptococcus neoformans
GRANULOMATOUS MENINGITIS (FUNGAL )
– Inflammation /infection of brain parenchyma
ENCEPHALITIS
- Inflammation /infection of leptomeninges (pia & arachnoid)
MENINGITIS
- Inflammation /infection of brain & spinal cord
ENCEPHALOMYELITIS
– inflammation of brain & meninges
MENINGOENCEPHALITIS
– inflammation of spinal cord
MYELITIS
E.Agent
- High risk – children 6 to 12 mons
- Newborn – most common is E.coli
Other causes:
: Grp B Streptococci &
: Listeria monocytogenes
ACUTE BACTERIAL MENINGITIS
- Older infants & children -
- majority due to Haemophilus influenzae type b.
- Children 1 mon. Of age & adults community-acquired meningitis:
- Most common due to Streptococcus pneumonia
- followed by Neisseria meningitidis
ACUTE BACTERIAL MENINGITIS
- causes gonorrhea, neonatal conjunctivitis (ophthalmia neonatorum), pelvic inflammatory disease (PID), Disseminated gonococcal infection
- also known as the gonococcus (plural, gonococci).
- Portal of Entry - GENITAL TRACT
- Neisseria gonorrhoeae
- causes meningitis and meningococcemia
- also known as meningococcus (plural, meningococci)
- Portal of Entry - RESPIRATORY TRACT
- Neisseria meningitidis
CHARACTERISTIC
> Gram-negative
> bacteria
> nonmotile;
> diplococcus, like kidney bean;
> piliated - can cause meningitis & other forms of meningococcal disease
> encapsulated
Neisseria meningitidis
> Large polysaccharide capsule.
One of the three classic encapsulated pyogenic bacteria (Streptococcus pneumoniae and H. influenzae are the other two).
Neisseria meningitidis
- epithelial lining of the nasopharynx normally serves as a barrier to bacteria.
- pathogenic strains may invade the bloodstream and cause systemic illness after an incubation period of two to ten days
NEISSERIA MENINGITIDIS
- BACTERIA
– other name : meningococcus. - transient flora of nasopharynx.
- Gr (-), coffee bean-shaped or kidney-shaped diplococcus
NEISSERIA MENINGITIDIS
> _____________ are distinguished by their propensity to evoke acute neutrophilic inflammation and “pus.”
- bacteria capable of causing local purulent inflammation or generalized infection (pyemia, sepsis).
pyogenic bacteria
- infection of ear
otitis media
- s/s : begins in throat
- enters bldstream causing bacteremia
- goes into meninges causing meningitis
- In susceptible persons, pathogenic strains may invade the bloodstream
Neisseria meningitidis
is defined as adrenal gland failure due to bleeding into the adrenal glands, commonly caused by severe bacterial infection
Waterhouse - Friderichsen syndrome (WFS)
- May coalesce & form larger hemorrhagic lesions
- Purpuric rash
- Progress to massive disseminated intravascular coagulopathy,
- Waterhouse-Friderichsen syndrome = w/ destruction of adrenal glands
Neisseria meningitidis
> Granulomatosis infantiseptica is caused when a pregnant individual is infected with ____________________, which often occurs because the individual eats contaminated food.
Listeria monocytogenes
is a bacterial pathogen that can survive at refrigerated temperatures.(it often contaminates soft cheeses, deli meats, hot dogs, milk, salads, fruits, and vegetables. ) rash will develop up to seven days after birth. Granulomatosis infantiseptica can also cause nodules to develop internally, specifically over the liver and spleen.
Listeria monocytogenes
- Gr (+) bacilli;
- slender, short, gram-positive rods
- facultative
- do not form spores
- cold-loving
- asymptomatic to Mild s/s;
- usually infects immunocompromised.
Listeria monocytogenes
– InIA (for Attachment and invasion)
Internalin A
– InIF (for Attachment and invasion) - surface protein w/ specific relevance for infection of host brain
Internalin F
– LLO (For Lysis of vacuoles) - enables to escape into the cytosol upon internalization
Listeriolysin O
(for cell to cell spread)
ActA
– LLO - (cell to cell spread) - has ability to damage plasma membrane of host cells
Listeriolysin O
- Can grow in CNS & placenta. (transplacental transmission)
- If pregnant, can lead to stillbirth or spontneous abortion
Listeria monocytogenes
- w/ formation of granulomas
- Chronic type
- Common cause: Mycobacterium tuberculosis & Cryptococcus neoformans.
- W/ remission & relapses
GRANULOMATOUS MENINGITIS
- > Pathogenesis—Granulomas and caseation mediated by cellular immunity (i.e., macrophages and CD4-positive T cells
- [delayed hypersensitivity]). Cord factor (trehalose mycolate) correlates with virulence. No exotoxins or endotoxin. Suppression of cell-mediated immunity increases risk of reactivation and dissemination.
GRANULOMATOUS MENINGITIS: Tuberculous meningitis
- Etiologic Agent: Fungus
- Caused by Cryptococcus neoformans
> MOT: inhalation of fungus fr. Envt.
> Infection spreads fr. Lung into bld affecting CNS - s/s: headache, N&V,loss of vision & other neurologic findings.
- DX: direct exam of CSF
- TX: amphotericin B & flucytosine for 4 to 8wks
Lifelong maintenance is required.
GRANULOMATOUS MENINGITIS
- Cryptococcus neoformans
- a yeast found worldwide.
- abundant in soil containing bird droppings
- Its spores are inhaled.
GRANULOMATOUS MENINGITIS: Cryptococcal meningitis
