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Nervous System Infections
Peripheral NS: botulism, tetanus, leprosy, polio, herpes simplex, varicella >>>> Central NS: meningitis, encephalitis, myelitis
FLACCID paralysis -- muscles do not contract, inhalation stops. Antitoxins from CDC bind the neurotoxin
Tetanus vaccine contains
antibodies to bind toxin, stimulates formation of antibodies to neutralize any future toxin, booster every 10 yrs. 50% of population no antibodies
CNS portals of entry
Skull or vertebral fx: staph spp. >>> medical procedures: lumbar puncture, epideral >>> climbs along peripheral nerves: rabies, HSV >>> via cribriform foramina: amoebas >>> via sinuses >>> Hemato-logous spread [MOST COMMON] across blood-brain barrier
CNS infections testing
CT scan for abcesses, tumors, cysts >>> Lumbar puncture LP for cerebral spinal fluid tests
Cerebral Spinal Fluid CSF tests
gram, capsule and acid fast stains, low glucose [suggesting bacteria], neutrophils [suggesting bacteria], lymphocytes [suggesting virus, TB, cryptococcus or HIV]
Bacterial meningitis symptoms
fever, headache, stiff neck [inflamed meninges causes pain so pt will not move neck], nausea >>> rapid progression to convulsions, coma
Acute Meningitis pathogens
Most common.  H. influenza  S. pnuemoniae  N. meningitidis >>> GNR, Listeria spp, and M. tuberculosis
GNR, capsule, aerobic: everyone has as normal nasopharyngeal flora, but if it crosses the blood-brain barrier ---> meningitis. Also otitis media, epiglottitis and pneumonia
N. menigiditis: a GN cocci, aerobic, w/ a capsule. Very rapid endotoxin damage. college/military
GP diplo-cocci capsule. 80% mortality elderly. Vaccination with capsule subunits from 7 strains
Meningitis mortality up to 30%. Systemic fungus with a thick capsule. IDed by CSF india ink stain. Pigeon droppings. Mild lung infection unless hematologous spread. Amphotericin B
Viral meningitis earmarks
Aseptic: meaning no growth in the usual cultures. CSF has elevated lymphocytes.
Arboviral encephaltis varieties
WEE, EEE, St. Louis, Calif., W Nile. All from mosquitos with bird-mammal reservoirs except Calif -- small mammal reservoir.
What kind of paralysis?
FLACCID paralysis with limbs and respiratory muscles affected -- can't inhale.
How does rabies virus get to encephalitis
virus travels along PNS into the CNS at rate of approx. 1 cm./day. A month to a year until encephalitis. Immune systems are ineffective because the virus is not traveling via the blood or lymph system
"Autonomic system instability" like fever, sweating, foaming. Delirium. Hydrophobia.
Post-exposure prophylaxis rabies
Rabies Immune Globulin RIG + a chick embryo vaccine called Human Diploid Cell Vaccine HDCV
Types of Sleeping Sickness
T. brucei gambiense: milder then brain damage >>> T. brucei rhodesiense: lethal
Upper respiratory infections
symptoms all look the same whether bacteria or virus. Normal flora is potentially pathogenic. We are talking sinusitis, pharyngitis, tonsillitis, otitis media, epiglottitis
the Common Cold is caused by:
50% Rhinoviruses, 15-20% Coronaviruses, and Mastadenoviruses. Altogether, there are over 200 causative viruses, and each one of those has multiple strains.
Otitis Media bacterial prevalence
S. pneumoniae [35%] >>> H. influenzae [20-30%] >>> M. catarrhalis [10-15%] >>> S. pyogenes [8-10%] >>> S. aureus [1-2%]
GAS has extra goodies
Steptokinases: lyse clots to allow spread of infection >>>>> Streptolysins: cytoxins to kill tissue, RBCs and phagocytes
GAS lab tests
Indirect Agglutination tests take 10 minutes, and you need to culture the tissue to determine sensitivity
Can lead to rheumatic fever and heart valve destruction. Scarlet fever is another toxin -- an erythrogenic toxin -- that causes skin splotching.
Diphtherial upper respiratory infections
GP rod, non-endospore. Pharyngitis with gray membrane of fibrin, dead tissue and bacteria. Toxins: cardio and neuro
Antibiotics do not affect the toxin, only CDC approved administration of antitoxins
Lower Respiratory infections
Normally sterile environment, no potentially pathologic flora. Larynx, trachea, bronchus, bronchioles, alveoli. Pathogens are inhaled
Bordetella pertussis: GN coccobacillus with a capsule. Tracheal cytotoxin damages ciliated cells -- Pertussis toxin enters the bloodstream and is assoc. w/ systemic symptoms.
Stages of pertussis
catarrhal stage: 1-2 weeks, like common cold ... violent coughing stage: 2-8 weeks ... convalescence: 1-2 weeks
Community Acquired Pneumonias
VEHICLES MF ... Varicella pneumonia virus, H. influenza GN coccobacillus, Chlamydiphila psittaci: GN intracellular, Legionella pneumophila GN, Strep pneumoniae, GP diplococci, Mycoplasma pneumo: GP pleo, Fungal pneumonias
Streptococcus pneumoniae: otitis media and menigitis along with pneumonia. Bleeding into aveoli, rust-colored sputum, 20% mortality in elderly, vaccination w capsular antigens
Chlamydophila psittaci: GN obligate intracellular. Bird droppings. Diagnosis via cell culture, Tx: Tetracycline
BACH: Blastomyces dermatitidis -- Miss Valley, extensive tissue destruction ... Aspergillus fumigatus: compost ... Coccidio-oido-mycosis immitis: Valley Fever, spores SW dust storms ... Histoplasma capsulatum: bird, bat droppings Miss Valley
TB skin test
PPD, or Purified Protein Derivative [coat of bacterium]. Definitive Diagnosis: chest x-ray and culture.
Positive x-ray with positive Acid Fast Bacterium sputum. X-ray looking for cavitating lesion called Ghon complex
Alveolar macrophages ingest bacilli, which are either destroyed or they start multiplying faster, immune response brings more macrophages. A tubercle with a cavity. Enlarges, invading bronchioles, capillaries
Attacks bones that have lots of marrow causing Pott's Disease -- a disabling scoliosis. Attacks all the organs causing Miliary TB -- named for millet seed-sized tubercles. Attacks testes. Attacks meniges and causes brain abcesses
Orthomyxo-virus Influenza A ... spreads from respiratory system to a systemic disease ... 16 subtypes of Hemagglutinin spikes ... 9 subtypes of Neuraminidase spikes or 144 in toto.
Influenza variation with gene changes to H or N surface proteins ... subtypes of strains in which virus avoids antibodies. "Expected Routine"
Influenza variation with changes to H and N combinations. Not different subtypes of strains, but different strains altogether. "Big Deal"
Major flu strains
1918 H1N1 Spanish evolved in pigs and humans ... 1957 H2N2 Asian replaced H1N1 ... 1968 H3N2 Hong Kong flu replaces H2N2 ... 2009 H1N1 Swine replaces H3N2
Many flu strains infect
humans, birds, and pigs. An animal can be infected with several strains at once -- the viruses can re-assort and maybe produce an entirely new strain
Fungus: Pneumocystis joroveci ... affects infants, immuno-suppressed, AIDs.
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