4.2.2_Micro

Causes of primary headaches

Causes of secondary headaches

What symptoms imply that you REALLY should worry about a headache?

Meningitis or Encephalitis
bacterial = septic serious
aseptic usually viral (alternatives are mycobacterial, fungal, noninfectious)

Meningitis or Encephalitis
acute, subacute, chronic
infectious, postinfectious, noninfectious

2.5 cases/100,000/yr10% deaths, 20% survivors w/ sequelae
Predominantly pediatric dz (75% <15yrs)
Usual pathogens part of normal upper resp. flora
Infection is a rare manifestation of colonization

Etiologic agents of bacterial meningits
a) newborns
b) most others
c) >60
d) post trauma
e) immune suppressed

Name the illness:
fever
headache
stiff neck
nausea/vomiting
lethargy/reduced mental status
seizures (rarely seen)
URI symptoms

How would you confirm a suspected meningits?

Brain abscess
Lateral vein thrombosis
subdural effusion or empyema
long term sequelae (deafness, hydrocephalitis, mental defects, ataxia, seizures)

collagen vascular dz's like SLE (systemic lupis)
sarcoidosis
Behcet's syndrome
subarachnoid hemorrhage
malignancy
durg hypersensitivity (ibuprofin and other NSAIDs, sulfonamides, cipro, heavy metals)

What should the practicing physician do if he suspects bacterial meningitis based on the clincial triad of symptoms?

Short chains of cocci
9 polysaccharide capsule types
lower GI tract is major reservoir
Frequent colonizer of female GI tract (10-30%) -- can lead to invasve dz in neonates
infections in elder too

What causes:
Acute infection in neonates: fever, lethargy, poor feeding, resp. distress (meningitis or sepsis present)
Late onset of neonatal infections (1-3 months)-- meningitis, focal infection of bone/joint
Adults: women postpartum
Elderly: pneumonia, meningitis, UTIs

Gram + bacilli
Colonies on culture plates look like Grp B strep
Eleven serotypes
Can grow in cold temps (refrigerators)
Colonizes many animals
Transmission to humans often by food (sausage, hot dogs, etc)

Common cause of food borne outbreaks of diarrhea
Multiple major meat product recalls
Serious dz: meningitis/bacteremia in newborns

Short gram + rods (may appear like cocci, may appear in pairs)
Small zone beta hemolysis
Catalase positive (all streps are catalase neg.)
Tumbling motility

Member Enterobacteriaceae
Neonatal Meningitis (transmitted at time of birth)

Important cause of meningitis in all age groups (predominantly babies and young adults, but all age groups affected)
Multiple serotypes (A,B,C,Y,W135)
Associated w/ both individual cases (sporadics) and epidemics
Outbreaks on college campuses (recommendations for immunization)
Normal flora in 5-15% of young adults
Colonization increases in closed pops.
Recurrent and severe infections associated w/ complement deficiencies of C6,C7,C8

Meningococcal syndrome

Vaccine: polysaccharide vaccine against A,C,Y,W135 (not B)
Antibiotic prophylaxis: intimate contacts in households (Rifampin still used, but antibiotic resistance has been described)

Free living ameoba found in shallow, fresh water (like warm weather)
Miningitis in summer months from swimming
Traverses nasal mucosa through cribiform plate to CNS
Starts olfactory bulbs and spreads in tissue
Severe bifrontal headache, seizure, changes in taste/smell
Death in days

Intracellular parasite
Oocysts are the "eggs" and are only created by sexual reproduction in cats (mature in soil)
Tissue cysts are capsulated collections of the trophozite form of the organism in muscle, brain, heart of intermediate hosts
Humans can ingest either oocysts (cats) or tissue cysts (undercooked meats) to become infected
Clinical: congenital dz (transmission in utero, catastrophic CNS dz)
Normal host dz: 2nd most common cause of mono
Immunosuppressed host: pneumonitis, myocarditis, encephalitis
Encephalitis: Multiple cystic lesions in the brain of Pt's-- often seen in HIV dz.

Coxsackie and echovirus
HHV6 (human herpes virus 6)
HIV
Adenovirus
EB virus
CMV
Mumps
LCM
Arboviruses
HSV
Rabies

Vaccinia
Measles
VZV
Rubella
EBV
Mumps
Influenza

Acute febrile illness
headache, fever
altered consciousness
disorientation
bx disturbances (change in personality)
focal neurological signs
seizures

Most common cause of sporadic disease
No seasonal pattern
1/3 <20, 1/2 >50 have had it
Not linked to immune status
70% mortality; few w/ full recovery
HSV1 the cause (except newborns)
begins in temporal lobe

25% have hx of cold sores
insidious or abrupt onset
fever always
headache
temporal signs: personality change, terror, hallucinations, bizarre behavior
40% get seizures
1/3 have hemiparesis
Aphasia (superior visual field cuts, facial parasthesias)
May have rapid progression to coma and death
EEG: slow wave activity

Most freq. cause of encephalitis world-wide (not US)
Mosquito and Ticks are vectors
Usually transmitted from birds/horses
Often have asymptomatic seroconversion
Pathogenesis: subcutaneous inoculation of virus by insect => local replication => spread to endothelial cells and RE system => spread to liver/brain/blood vessels => cell death and inflammation

Diagnosis of Encephalitis: Lab

Prevention of Encephalitis

Incidence reported as 10-15% of all cases
Vaccinia and measles used to cause most
Resembles other forms, but hx includes: exanthem or prior resp, tract illness
Is felt to be a form of autoimmune response to recent infection

Rabies epidemiology

Mania
hyperactivity followed by somnolence
paralysis
hydrophobia
virtually always fatal

Differences between meningitis and encephalitis

Describe the flow of CSF, where it is made, and what purpose it serves.

What type of infections occur in the
a. epidural space
b. subdural space
c. subarachnoid space
d. brain

Has abundant neutrophils in subarachnoid space

Necrotizing vasculitis causes this.

Usually self-limited -- resolved in 7-10 days.
Lymphocytes, not PMNs in blood and CSF

Rare except in immunocompromised
Headache, effets of edema (minimal inflammation)

In meninges, but also invades brain
See caseating granulomas as in other sites
Can have slow or fulminant course, poor prognosis

2nd most common serious CNS infection (to meningitis)
Caused by Hematogenous spread -- bacterial endocarditis, dental extraction, congenital heart dz w/ R to L shunt, immunocompromised.
Direct spread: penetrating head trauma, sinusitis
Presentation: mass effects, high intracranial pressure
Focal Signs: May or may not have features of sepsis
Treatment: drainage or removal plus antibiotics

From cat feces or raw meat
causes mild or no illness if healthy (problomatic in AIDS and fetuses)
Severe necrotizing encephalitis
Altered mental state, focal neurol changes
Ring enhancing hypodense on CT
Intracellular cysts

Rare in US, common in Latin America, Africa, Asia
Most common cause of seizures worldwide
From undercooked pork or pig feces (pig tapeworm)

Usually in neutropenic Pts

Angioinvasive, from sinus infection
Causes infarct

Patchy lymphocytic infiltrate in brain (microglial nodules)
HIV can directly involve CNS, causing dymentia
Commonly caused by: HSV, Rabies, Arbovirus, Enterovirus, Mumps, Measles, Lymphocytic Choriomeningitis, JC virus and others

70% death rate without Rx
Severe sequelze common in survivors
Mostly in temporal lobes
Fever, HA, personality changes, seizures

Long incubation (months to a year) while virus climbs to brain from peripheral nerves
Tingling at bite site, then manic, somnolent, hydrophobic, paralyzed, death (survival is very rare)
See red inclusions in neurons (negri bodies at arrows)

Clinical presentation: Fever, malaise, mental status changes, miningeal irritation signs (headache, stiff neck, irritable, n/v)
Spinal tap: culture. microscopic exam, protein, glucose, Gram stain, sometimes antigen-antibody testing for specific organisms
Sequelae: immediate & short term: sepsis, DIC, seizures, herniation, sinus thrombosis
Late: hydrocephalus, seizures, cranial nerve changes, infarcts

Aseptic meningits agents

Reproduce in gut (although they do not necessarily produce GI dz)
Worldwide distribution (5-10 million symptomatic infections/yr)
Major cause of aseptic meningitis in children and young adults (90%)

90% of aseptic meningitis in children and young adults
fever, chills, headache, photophobia, n/v
Nonspecific: diarrhea, myalgias, rash, pleurodynia
Rare complications or sequelae
Encephalitis (rare): lethargy, disorientation, seizures (paralysis, Guillan-Barre have also been seen)

Outcomes of Aseptic meningitis

Prevalent in dust containing bird droppings
Different subtypes
Pathogenesis: capsule that promotes attachment and invasion
Organism inhaled and disseminates from lung
Causes Meningitis (other sites: lung, bone skin, prostate)

Notice the budding yeast. (organism is black)
Variable size of yeast cells. Only yeast that causes CNS disease.

Diagnosis of Cryptococcus