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73 Cards in this Set
- Front
- Back
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3 Basic Structural Considerations of the CNS
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1) Bone and meningeal coverings compartmentalized infections
2) BBB mostly excludes both microbes and immuncompetant cells & antibodies 3) subarachnoid space contains CSF |
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Disease condierations of the CNS
Origin, spread |
Epidural infxn arise from osteomyelitis & remain localized
once bacteria penetrate subdural space, infx spreads rapidly over a cerebral hemisphere once within the subarachnoid space, infxn spreads via CNS w/o host resistance parenchymal infections tend to be lcoalized if organismal or diffuse if viral |
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Encephalitis
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inflammation of the parenchyma of the CNS
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Meningitis
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inflammation from an infection within the subarachnoid space
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Important CNS Agents: Bacteria, Fungi, Parasites
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Bacteria: Strep pneumoniae, Neisseria meningitidis, Haemophilus influenzase b, Strep agalactiae, Listeria monocytogenes
Fungi: Cyrotococcus neoformans Parasites: toxoplasma gondii, angiostrongylus cantonensis, Taenia soliu, echinococcus spp, baylisacaris procyanis |
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Acute vs. Chronic Meningitis
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Acute onset of hours to days
Chronic: persistence or progression for >=4 wks |
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Portals of Entry for CNS disease
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2ndy invasion from bloodstream
penetrating injury contiguous spread from nasal sinus, middle ear, nearby infxn intra-axonal transport |
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Predisposing Factors for Meningitis
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Community-Acquired: COlonization of respiratory tract (Neisseria meningitids, Strep pneu, Hib
Hospital acquired: Iatrogenic, altered immune status: GNR's, Staph aureus, other staph and strep |
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Pathogenesis of bacteiral meningitis
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1. mucosal surface is colonized
2. bacteremia 3. BBB penetration 4. host response: inflammatry cytokines 5. WBC's enter CSF via diapedesis 6. increased permeability of BBB, education 7. edema, increased intracranial pressure and altered blood flow. |
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Diagnosis of CNS Disease:
Sx, Hx, Labs, Identifying Agent |
Hx: Previous URI is common
Sx: Fever, HA, ocular pain, stiff neck, n/v, confusion Labs: any PMN's or >5WBC's/ml, decreased glucose, elevated protein Direct smear of CSF examined via wet mount, gram stain, imaging ID: Rapid Antigen Detection Tests, PCR, Blood Cultures should be performed (hematogenous dissemination) |
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Treatment of CNS Disease
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Medical Emergency
Direct methods are used as guide to empiric therapy Must penetrate BBB Must be -cidal -Synergistic combinations are used emperically final choice is based on susceptibility data |
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irritability, lethargy, severe HA, fever, moviting, nuchal rigidity, photophobia, convulsions, coma, >2yo
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Purulent Meningitis
fulminant course w/o tx, death within hours 10% mortality, 40% neurologic sequalae |
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Hyperthermia, Lertharygy, Irritability, Sizures, GI disturbance, Respiratory Abnormalities in Neonate
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Neonatal Meningitis (up to 60% mortality)
Poor prognosis, survivors have permanent defects |
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Neonatal Meningitis Risk Factors
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Maternal:
premature membrane rupture late term ug infxn early term intrauterine infxn invasion of uterine space Neonatal factors: immature defense mechanisms low birth weight, immature organs CDC recommends universal prenatal screening for vaginal and rectal colonization with group B strep for all pregnatns 35-37 weeks routine antibiotic prophylaxis for culture+ women unless underoing planned cesarian deliveries w/o membrane rupture |
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Sx of Neonatal Meningitis
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Different from adults
Hyperthermia, Lertharygy, Irritability, Sizures, GI disturbance, Respiratory Abnormalities in Neonate |
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PRedominant agest oof neonatal meningitis
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Streptococcus agalactiae
E Choli Listeria Monocytogenes |
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Streptococcus agalactiae
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encapsulated group B streptococcus, mostly Beta hemolytic, normal flora of vagina;
virulence factors: capsular polysaccharide, hyaluronidase, collagenase leading cause of bacteremia with meningitis in neonates, 50% mortality rate Most cases transmitted during delivery early onset of disease: sx w/in 5 days, commonly w/ maternal obstetric complications. presents as bacteremia, pneumonia and meningitis late onset: &days-3 mos w/o maternal ob complications; major manifestations bone joint infections, bacterimia with fulminant meningitis Reliable presumptive tests: capsular polysaccharide antigen detection tests, DNA probe tests excellent. Definitive Diagnosis re's isolation from blood, CSF, suppuration |
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leading cause of bacteremia with meningitis in neonates
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Streptococcus agalactiae
encapsulated beta hemolytic group B streptococcus; part of the normal flora of the vagina early onset of disease: sx w/in 5 days, commonly w/ maternal obstetric complications. presents as bacteremia, pneumonia and meningitis late onset: &days-3 mos w/o maternal ob complications; major manifestations bone joint infections, bacterimia with fulminant meningitis |
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E coli & Meningitis
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Gram negative enteric bacillus
meningitis caused by encapsulated K1 strains infection from vaginal colonization from mother's rectum |
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K1
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capsular protein of E-coli
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Listeria monocytogenes
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facultatively-intracellular gram positive motile coccobacillus w/ "tumbling motility" & anti-phagocytic LPS-like component,
non-fastidious extremely adaptable worldwide environmental distribution: plants, soil, fece. ingested in raw/undercooked food of vegetable & animal origin; occurs in outbreaks (food processing); normally eliminated, in immunocompred monocytes, macrophage, and epithelium invaded, summer infxn (picnics) acquisition in utero: stillbirth/abortion or pneumonia, seizures, skin lesions, high mortality neonatal acquisition in vaginal tract: meningitis adult: leading meningitis in CA and renal transplant pts; brain inflammation. Defense is T cell CMI; Ig only partially protective (intracellular) Dx: culture, else DNA probe. lab must grind-up cells (intracellular) & low O2 tension |
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miningitis following a picnic,
kids did't wash hands before eating |
Listeria monocytogenes
facultatively-intracellular gram positive motile coccobacillus w/ "tumbling motility" & anti-phagocytic LPS-like component which invades from the GI tract after raw/undercooked/soil/feces contaminated food consumption |
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hanging drop preparation from meningitis pt reveals "tumbling motility"
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Listeria monocytogenes
facultatively-intracellular gram positive motile coccobacillus w/ "tumbling motility" & anti-phagocytic LPS-like component which invades from the GI tract after raw/undercooked/soil/feces contaminated food consumption |
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Leading cause of meningitis in CA pts
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Listeria Monocytogenes
facultatively-intracellular gram positive motile coccobacillus w/ "tumbling motility" & anti-phagocytic LPS-like component which invades from the GI tract after raw/undercooked/soil/feces contaminated food consumption |
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Leading cause of meningitis in renal transplant pts
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Listeria Monocytogenes
facultatively-intracellular gram positive motile coccobacillus w/ "tumbling motility" & anti-phagocytic LPS-like component which invades from the GI tract after raw/undercooked/soil/feces contaminated food consumption |
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Winter Meningitis
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S agalactiae in neonates <1 mo & adults
S penumoniae 1mo-4 yo + elderly adutlts N meningitidis 1mo-19 yo H influenzae type B late winter/early spring infants 7-18 mo |
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gram positive motile coccobacillus causing meningitis
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Listeria Monocytogenes
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Haemophilus influenzae
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fastidious encapsulated gram negative, non-motile, pleomorphic coccobacillus
Colonizes nasopharnx of healthy pts, invades blood/lymph of at risk: Natives, Humorally Def, SocEc: Crowding, Daycare, Smoke, Bottle Fed non typable = floral, opportunistic: adult meningitis + various Hib = invasive: meningitis, epiglottitis, bactermia; insidious onset following URI or otitis media VF's: LPS-like LOS Lipooligosaccharide for attachment damages epithlium PRP Polyrisoylphosphate capsule resistant to phagocytosis, [neuraminidase & IgA protease, fimbrae] Dx: detection of CHO PRP capsular antigen in CSF serum or concentrated urine, [PRP] & duration of it, useful for prognosis Susceptibility tests are essential! Chemoprophylaxsis for family/contacts |
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Meningitis after URI
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Haemophilus influenzae: Fastidious encapsulated gram negative, non-motile, pleomorphic coccobacillus
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Meningitis after Otitis Media
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Haemophilus influenzae: Fastidious encapsulated gram negative, non-motile, pleomorphic coccobacillus
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Prevention of Hib Meningitis
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Various formulations of conjugate vaccines available
usually PRP (capsular CHO) + adjuvant chemoprophylaxis of contacts |
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gram negative, non-motile, coccobacillus causing meningitis
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Haemophilus Influenzae
fastidious, maybe encapsulated |
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Streptococcus Pneumoniae
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[alpha-hemolytic green] encapsulated gram positive lancet shaped non-motile non-fastidious diplococcus with a antiphagocytic capsule;
aspration, maybe pneumonia, dissemination, many deseases incl meningitis esp elderly presents as an acute purulent meningitis Dx: mucoid alpha-hemolytic gram lancet shaped diplococci grown from CSF; demonstrate not common viridans w/ demonstration of either optochin susceptibility or bile solubility or quelling reaction |
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Meningitis after Pneumonia
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streptococcus pneumoniae: [alpha-hemolytic green] encapsulated gram positive lancet shaped non-motile non-fastidious diplococcus with a antiphagocytic capsule;
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[virulence factors of strep pneumoniae]
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pneumolysin forms transmembrane pores and lyses target cell;
autolysin suicide bomber, releases pneumolysin vs host/stasis peptidoglycan teichoic acid complex potent immune response, IgA Protease, Hydrogen peroxide kills host cells/eliminates competition, PIli for UR attachment Choline binding adhesin proteins for LR attachment |
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purulent meningitis
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streptococcus pneumoniae: [alpha-hemolytic green] encapsulated gram positive lancet shaped non-motile non-fastidious diplococcus with a antiphagocytic capsule;
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Elderly CNS disease, most common agent
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streptococcus pneumoniae: [alpha-hemolytic green] encapsulated gram positive lancet shaped non-motile non-fastidious diplococcus with a antiphagocytic capsule;
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Vaccination vs Strep Pneumococcus
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13 valent conjugate vaccine for high risk pts infants children elderly
23 valent vaccine recommended for all 65+ |
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gram positive cocci in pairs causing meningitis
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strep pneumoniae: [alpha-hemolytic green] encapsulated gram positive lancet shaped non-motile non-fastidious diplococcus with a antiphagocytic capsule;
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Neisseria minigitidis
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aka meningococcus: encapsulated fastidious, gram negative, kidney bean shaped diplococcus
human nasopharynx sole reservoir, w/ both non & immune chronic cariers different serotypes, no vaccine to serotype B Sporatic and epidemic: req's close contact & fatigue: college students, recruits Manifestations: rash = bactermia, may resolve, maybe acute meningitis DIC , Gram neg shock Waterhouse-Friderchsen Syndrome in children = hemorrhagic adrenal infarction Atypical in infants: irritability to coma and death Dx: skin rash, gram stain CSF, culture blood/CSF, detect capsular polysach in CSF |
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gram negative, kidney bean shaped diplococcus causing meningitis
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Neisseria minigitidis: encapsulated fastidious, gram negative, kidney bean shaped diplococcus
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hemorrhagic adrenal infarction
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Waterhouse-Friderchsen Syndrome
a possible complication of Neisseria minigitidis menningococcemia Neisseria minigitidis: encapsulated fastidious, gram negative, kidney bean shaped diplococcus |
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Waterhouse-Friderchsen Syndrome
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hemorrhagic adrenal infarction
a possible complication of Neisseria minigitidis menningococcemia Neisseria minigitidis: encapsulated fastidious, gram negative, kidney bean shaped diplococcus |
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Meningitis after Skin Rash
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Neisseria minigitidis: encapsulated fastidious, gram negative, kidney bean shaped diplococcus
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Prevention of N meningiditis
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chemoprophylaxsis to close contacts
routine tetravalent polysach protein conjugate vaccine for children & adolescents |
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Bacteremia vs. nervous tissue
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highly resistant to bacterial infvasion
damage to brain more likely from rupture of mycotic aneurism than from sustained bacteremia |
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When do brain abscesses form?
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Events:
chronic cerebral anoxia suppuration of adjacent bone/sinus --otitis media/mastoiditis-->temporal lobe/cerebellum --dental sepsis--> frontal lobe abscess septic embolization (endocarditis, any distal infxn)--> multiple locations surgical trauma |
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Most Likely Organisms of Brain Abscess
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generally polymicrobial
In descending order Streptococci (intermedius group including anginosus, not S pnue) Bacteroides & Prevotella of the obgliately anaerobic bacteria, Bacteroides fragilis is most common isolate |
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Virulence Factors of Bacteroides fragilis
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neuraminidase
hyaluronidase LPS activates hageman factor: intrinsic coagluation pathway polysach capsule vs chemotaxis, phagocytosis, killing |
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Increased Intracranial Pressure
Focal Neurological Signs Low Grade Fever |
Brain abscess: usually streptococci intermedius group (not pneu), bacteroides & prevotella
CT/MRI Lumbar Pnx contraindicated Tx: empirical antibiotics, most require surgery: aspiration or excision |
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Subdural Empyema
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an intracranial collection of pus located between inner surface of the dura and outer surface of the arachnoid
usually either: infxn of paranasal sinuses w/ indirect extension via venous system, or otitis media w/ direct extension via bone erosion acute onset Imaging Good, CSF uncolonized |
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Spinal Epidural Abscess
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a mass of puss located outside the dura mater within the spinal canal
Majority = Staph aureus in acute cases purulent necrosis of epidural fat in chronic cases dura is grey and thickened, epidural fat replaced by granulation tissue paralysis is permanent and mortality rate is high Dx: myelography & CT |
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Malignant external otitis
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an infxn of extrnal auditory canal which invades adjacetn tissue and temporal bone
almost always pseudomonas aeuginosa rapidly evolving pain w/ swelling of parotid, trismus, paralsysis of CNS 7-XII |
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rapidly evolving ear pain with swelling of parotid, trisumus and facial nerve paralysis
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Malignant external otitis
an infxn of extrnal auditory canal which invades adjacetn tissue and temporal bone almost always pseudomonas aeuginosa rapidly evolving pain w/ swelling of parotid, trismus, paralsysis of CNS 7-XII |
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CNS manifestations of bacterial endocarditis
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cerebrovascular disease (strokes)
toxic encephalopathy- confusion, delerium, hallucinations |
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Big 3 Granulomatous Diseases
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TB
Syphilis Leprosy (Hansen's Disease) |
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Leprosy Vaccine
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Not Effective, Not Used in US
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Mycobacterium leprae
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acid fast obligately intracellular bacillus, must grow in M0 & schwann
infects primates, carried by armadillos; prevalent on southern edge of country (TX, CA, LA, FL) incubation of 5+ years is typical, dvlpt depends on CMI response. early sx: hypopigmeented macule, then leonine facies, claw hand Optimal temp <37 degrees w/ granuloma formation & denervation. Manifestations: many initially manifest as any form TT: Tuberculoid, LL: Lepromatous, Progression from TT to LL represents switch from CMI to ineffectual AMI w/ corresponding increased bacterial load; BB: Borderline, BT more like TT, BL more like LL Definitive Dx: demonstr bacilli, likely in LL, improbab in TT Lepromin skin test useful for prognosis not Dx UnTx: multi-organ invovlemtn & death |
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Disease carried by Armadillos
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Mycobacterium leprae
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Hypopigmented lesions
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First Manifestation of Mycobacterium leprae
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Leonine Fascies
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Widening of inter-orbital area/swelling of upper nasal area in leprosy
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Obligate anaerobes
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THINK BACTEROIDES
some spirochetes some gram negative bacilli some gram positive cocci & bacilli: Clostridii: perfringes, difficile botulinum & tetani |
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Clostridium perfringes
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large anaerobic gram + motile rods (all Clostridia)
perfringes esp associated with myonecrosis (gas gangrene) and food poisoning |
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Costridium difficile
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large anaerobic gram + motile rods (all Clostridia)
difficile esp associated with pesudomembranous colitis |
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large anaerobic gram + motile rods
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Clostridia
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Clostridium tetani
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large anaerobic gram + motile rods (as all clostridia), tanti has terminal spores, only one serotype, easy to immunize
common in soil, human & animal GI flora, req enter via trauma find anaerobic environ, plasma mediated tetanospasmin released via autolysis, acts on central motor control, ANS fnx & NMJ, inhibits NT release from inhibitory interneurons-->trismus: lockjaw; risus sardonicus: tetanus facies; opisthonos = rigid back highly fatal cardiac/respiratory complications At risk: neonates & IV drug users Dx: clincial presentation, demonstrate toxin in feces |
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Clostridium botulinum
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large anaerobic gram + motile rods (as all clostridia)
eight serotypes some differences, subterminal spores, phage mediated endotoxin, affects peripheral NMJ & ANS synaspes, blockes release of ACh at jnx, flaccid paralysis, less fatal spores worldwide in soil, GI tract of animals foodborne due to home canned goods, ingest toxin sporadic infant botulism from contaminated honey, GI colonization sporadic wound botulism from soil contamination into avascular areas, drug use Isolated cases from GI colonization First GI sx then respiratory paralysis, also fixed dilated pupil & dry furrowed tongue Dx; clinical, no fever, responsive pt, no sensory deficits |
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Tetanus vs Botulism
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Both large anaerobic gram + motile rods (as all clostridia), toxin release by autolysis, preventable via education and public health measures
Tetani: only one serotype, terminal spores, plasma mediated toxin, affects inhibitory interneurons of CNS, inhibits orelease of NT substances, spastic rigidity, highly fatal Botulim: eight serotypes, subterminal spores, phage mediated endotoxin, affects peripheral NMJ & ANS synaspes, blockes release of ACh at jnx, flaccid paralysis, less fatal |
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Risus Sardonicus
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Tetanus Facies
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Opisthotonos
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Rigid Back in Tetanus
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Localized tetanus
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Spastic rigidity confined to extremities
may last for months but usually resolves spontaneously rare form of disease in people inadequately immunized |
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Cephalic tetanus
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result of a head wound:
spastic rigidity on only the face |
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Responsive, afebrile patient with symmetric neurologic manifestations & blurred vision, no other sensory deficits
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Botulism
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