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107 Cards in this Set
- Front
- Back
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How do parenchymal infections of the brain with bacteria tend to be distributed?
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localized
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How do parenchymal infections of the brain with viruses tend to be distributed?
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diffuse
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What is meningitis?
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infection in the subarachnoid space
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what is encephalitis
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inflammation of the parenchyma
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what things typically cause acute meningitis? (generally)
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viruses
rickettsiae bacteria spirochetes protozoa helminths |
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What things typically cause chronic meningitis (generally)?
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parasites
fungi some bacteria or fungi |
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How do most bugs get into the CNS?
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these usually come via the blood- which got into the blood via the respiratory system
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What does meningitis, community acquired, usually follow?
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respiratory tract infections with neisseria, strep, H. influenzae
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how are WBC's an agent in causing meningitis pathology?
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these go into the CSF, and in doing so increased permeability of BBB, which then creates edema, increased pressure, and lots of problems
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what are the most common signs of CNS disease?
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headache
stiff neck nausea vomiting confusion fever Previous URI*** |
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What are the CSF findings in meningitis?
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presence of PMN's or +5 WBCs/mm3
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What are two important qualities of a good drug to treat meningitis?
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must penetrate BBB
must be bactericidal |
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What age group usually get purulent meningitis?
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children older than 2 years old and adults
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What are the sings of purulent meningitis?
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irritability, lethargy, headaches, fever, vomiting, nuchal rigidity, photophobia, convulsions, coma
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What is the usual course of purulent meningitis without Tx?
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death!
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What percent of purulent meningitis survivors have neurologic sequeale?
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30-50%
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What are the common neonatal factors that predispose them to meningitis?
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premature and low birth weight
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What are the maternal factors that lead to neonatal meningitis?
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premature rupture of membranes
UTI's invasion of uterine space |
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What are the signs of neonatal meningitis?
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very irritable
seizures GI disturbance respiratory abnormalities High or Low body temp |
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what is the prognosis for neonatal meningitis?
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very poor, 10-60% fatal
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What is the morphology of Strep agalactiae? (and its virulence factors)
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Group B, beta-hemolytic
capsular polysaccharide has hyaluronidase and collagenase |
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What bug is the leading cause of bacteremia with meningitis in neonates?
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strep agalactie
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How do most neonates acquire strep agalactiae?
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during delivery
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how high is mortality with strep agalactiae?
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50% mortality rate
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When does early onset strep agalactiae occur? late onset?
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early onset is within first 5 days of life
late onset is 7 days to 3 months of age |
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How do you diagnose Strep agalactiae?
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can isolate strep agalactie from sterile areas like blood and CSF
Can also use DNA probes, CAMP factor, Ag detection |
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What types of E coli causes neonatal meningitis?
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Encapsulated K1 strains
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Where does K1 E. coli come form?
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rectal bacteria colonizing the vagina
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What type of bug causes meningitis in college students, military and so forth?
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Nissearia Meningitidis
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What is the morphology of Listeria Monocytogenes?
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G+ motile coccobacillus
grows in a wide variety of temps |
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Where is Listeria usually found?
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in found in living and non living matter, typically foodstuffs -> leads to common source outbreaks
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is Listeria a reportable disease?
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yes it is
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Does listeria affect immunocompetent hosts?
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no it does not, but it takes only a slight defect (pregnancy, mild illness, asthma etc)
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what types of cells does listeria infect?
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mononuclear cells
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How do neonates acquire listeria that leads to meningitis?
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this is during birth from the genital tract
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what is immunity to listeriosis mediated by?
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t cells
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What should you do if you suspect listeriosis?
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alert the lab, because they must grind up the cells before plating
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What is a characteristic of listeria in a drop preparation?
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it has tumbling activity
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What does H. aegypticus cause?
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conjunctivitis and brazilian purpuric fever
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What does H. ducreyi cause?
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chancroid
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What are the risk factors of Hib?
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day care, siblings, crowded house, not breast feeding.
being native american/alaskan |
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Where does Hib colonize?
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the nasopharynx of healthy kids and adults
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What are the virulence factors of HIb?
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capsule
type B strain Lipooligosaccharide cell envelope |
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What is the typical clinical signs of Hib Meningitis?
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antecedent URI or otitis media
- shows as several days of mild infection that deteriorates insidiously*** to meningitis |
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How do you diagnose Hib?
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CSF gram stain
***detecting capsular antigen in CSF, serum, or urine |
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Who does penumococcal meningitis usually affect?
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the elderly, or people with recurrent meningeal infections
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Is there often an antecedent for pneumococcal meningitis?
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no
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What are the sings of penumococcal meningitis?
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similar to other bacterial meningitis.
acute onset and progression marked inflammation of meningies, very purulent |
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how do you diagnose pneumococcal disease?
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alpha hemolytic, and mucoid colonies due to capsule.
Bile sensitive** Optochin sensitive** Quelling RXN*** - (shows the capsule) |
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What is the drug of choice of pneumococal infections?
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Penicillin G
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What is the morphology of Nisseria?
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G-, kidney bean shaped diplococcus, Encapsulated.
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What are the Signs/characteristics of meningococcemia?
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RASH** over whole body within hours
otherwise similar to other acute meningitis. Spread by close contact |
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What is the reservoir of Nisseria?
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nasopharynx colonization in HUMANS only
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What major problems can occur with Nisseria?
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DIC, G- shock, Waterhouse-Friderichsen syndrome (hemorrhage into adrenal tissue)
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What unique about the control of Nisseria infections?
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you give chemoprophylaxis to at risk groups***
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what is usually the make up of paramenigneal infections?
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these are usually mixed species, in a walled off space - forms and abscess
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What usually leads to parameningeal infections?
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usually secondary to infection of ear, sinus, or skull bones near by
can also be infection metastasis from other locations |
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What types of bugs usually leads to parameningeal infections?
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these are usually Anaerobic infections
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What is the most common obligate anaerobe associated with parameningeal infections?
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Bacteroidies fragilis
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What are the special virulence factors of Bacteroids fragilis?
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G-
neuraminidase hyaluronidase LPS capsule (which can cause coagulation) Polysaccharide capsule interferes with killing |
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What is the pathogenesis of a Brain abscess?
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bacteria into brain->inflammation, then
early-> late cerebritis early-> late capsule, then abscess finally |
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Do brain abscess usually come from bacterial meningitis?
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no hardly ever
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What are the clinical manifestations of brain abscess?
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low grade fever
increased intracranial pressure produces progressive severity, with neurologic deficits |
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How do you diagnose brain abscess?
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high index of suspicion
CT or MRI Do NOT do a lumbar puncture |
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how do you cure brain abscesses?
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surgery intervention
drug choice is bug specific |
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What are the top three bugs that cause brain abscess?
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Strep intermedius
Bacterioidies family (including fragilis) and Enterobacteriaceae |
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What bug usually causes malignant external otitis?
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pseuomonas aeruginosa
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what can malignant external otitis progress to?
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this can infect the bone, and then move into meningitis/CNS infection
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What is the clinical presentation of Malignant external otitis?
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rapid ear pain, w/ w/o discharge.
swelling of parotid gland, trismus (inability to open mouth), and paralysis of CN VI-XII |
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What bug causes leprosy?
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mycobacterium leprae
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What is the morphology of mycobacterium leprae?
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Acid fast bacillus
obligate intracellular pathogen grows in histocytes, macrophages, and schwann cells |
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What three things can be infected with leprosy?
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humans, monkeys, and armadillos**
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Who usually gets leprosy?
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mostly seen in teenagers and young adults
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What is leprosy infection related to?
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the adequacy of CMI
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what is the major problem with leprosy?
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this causes granuloma formation and nerve destruction
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what parts of the body does leprosy usually affect?
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the cooler parts of the body, so the peripherally
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what is the earliest sign of leprosy infection?
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hypopigmented lesions (like white patches of skin)- may have anesthesia
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what is the first form of leprosy that is affected by cell mediated immunity?
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tuberculoid leprosy
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what is the final form of leprosy that is affected by antibody mediated immunity?
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lepromatous leprosy
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What are the clincial characteristics of tuberculoid leprosy?
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skin lesions are granulomatous and hypopigmented, with raised edges and a flattened dry center
peripheral nerve invasions causes anesthesia in lesions |
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What are the diagnostic factors of leprosy?
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residing in an area endemic to leprosy/ contact with lepers
skin smear or biopsy looking for acid fast bacliil lepromin skin test |
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When you hear obligate anaerobe, what bug should you think of?
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bacteriodies (fragilis)
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What is the morphology of the important Clostridia?
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found in soil and in normal flora
the pathogenic ones are usually G+ produces spores, and exotoxins**- causes disease |
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Where does the spore form in C. Tetani?
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this is a terminal spore
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What are the risk groups for Tetanus?
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Newborns and IV drug abusers
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how does tetanus get into the body?
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via traumatic implantation
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is Clostridia aerobic or anaerobic?
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it is anaerobic
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what is the chemical that causes tetanus?
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tetanospasmin, prevents the firing of inhibitor interneurons- leading to constant contraction
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What is risus sardonicus? and what causes it?
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this is a fixed smile on the face cause by tetanus
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what is opisthotonos?
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this is rigidity of the spine caused by tetanus
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who usually gets localized tetanus?
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someone who is inadequately immunized
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how do you diagnose tetanus?
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clinical symptoms
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How do you treat tetanus?
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active immunization with tetanus TOXOID**
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What do you give to suspected causes of tetanus?
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HTIG human tetanus immune globulin
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What is the morphology of Clostridium botulinum?
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anaerobic (like all clostridium)
Subterminal spore* Produces exotoxin |
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where is Botulism found in nature?
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soils and sediments, in the GI tracts of birds fish and mammals
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What is botulism usually associated with?
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home-canned foods
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What usually causes infant botulism (sporadic)
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ingesting honey that is contaminated with spores
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what is wound botulism usually associated with?
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deep wounds/ IV drug use
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With food poisoning botulism, what do we ingest?
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neruotoxin produced by botulism
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with infant botulism, what do they ingest?
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ingest spores of botulism
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what does botulism toxin do?
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this blocks ACH release (flaccid paralysis)
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What are the main diagnostic features of botulism?
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no fever
symmetric neurologic manifestations pt is responsive sensation is intact Confirmed by toxin in feces or via culture*** |
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What governs toxin production in tetanus?
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plasmid gene
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What governs toxin production in botulism?
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bacteriophage
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How many antigenic types are there for tetanus
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just one
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How many antigenic types are there for botulism
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eight
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