Download Fitzhugh - ID Board Review

Infectious Disease Board Review
Dave Fitzhugh, MD
June 16, 2009
Bacterial meningitis
• Strep pneumo is most common cause in US
(47%), with 19-26% mortality
• Often develops in conjunction with PNA,
otitis media, mastoiditis, endocarditis or s/p
head trauma
• All children (and adults >65) should be
vaccinated at this point
Meningococcemia
• #2 cause of bacterial meningitis in US
• Typically, kids/young adults
• Pts with complement deficiencies (C5-C9) at
increased risk
• Vaccine available, typically only high risk
population (college dorm residents, asplenia,
travellers, microbiologists)
• Petechial rash which can progress to purpura
fulminans, indicating DIC/sepsis
Other causes of meningitis
• Listeria – associated with GI portal of entry (raw
vegetables, milk, cheese, processed meats)
• GBS – typically in neonates. In adults with DM,
EtOH, HIV
• Gram negative – Klebsiella, E coli, serratia,
Pseudomonas typically Nsrg pt or head trauma
• Haemophilus – rare now given childhood vaccine
• Staph aureus – usually Nsrg or head trauma, but
also with DM, EtOH. Coag neg staph with CSF
shunt
Meningitis Dx
• CT prior to LP if seizure, papilledema,
AMS, focal neurological deficit, h/o CNS
dz, immunocompromised
WBC
count
Diff
Glu
Pro
Bacterial
Viral
1000-5000 50-1000
TB
50-300
Crytpo
20-500
PMN
<40
100-500
Lymph
<45
50-300
Lymph
<40
>45
Lymph
>45
<200
Meningitis Tx
• Empiric therapy if delay in LP
• Consider adjunctive dexamethasone in
suspected or proven S pneumo meningitis
(given only with or just prior to 1st dose
abx)
• Target Abx if you have Gram stain
information
Empiric Meningitis Therapy
Age 2-50
S. pneumo, N.
meningitidis
Vanc +3rd gen
cephalosporin
Age >50
S. pneumo, N. men,
Listeria, GN bacilli
Vanc +3rd gen
cephalosporin +
ampicillin
Basillar skull fracture
S. pneumo, H.influ,
group A strep
Vanc + 3rd gen
cephalosporin
Post-NSG or trauma
Staph, Gram negative:
Pseudomonas
Vanc + either ceftaz,
cefepime, or
meropenem
CSF shunt
Staph aurues, CONS,
GNR
Vanc + either ceftaz,
cefepime, or
meropenem
Review Questions
•
•
•
•
•
MKSAP 16
MKSAP 33
MKSAP 14
MKSAP 97
MKSAP 19
Syphilis
• Primary syphilis presents as a painless ulcerative chancre approx 3
weeks after exposure to Treponema pallidum
• Primary lesion usually resolves and progresses to secondary syphilis 28 weeks later
• Secondary syphilis is characterized by hematogenous dissemination in
the skin, liver, lymph nodes usually resolves and progresses to latent,
tertiary or neurosyphilis
• Latent syphilis is asymptomatic infection with positive serology
• Tertiary syphilis includes CNS, cardiovascular and gummatous disease
involving skin, soft tissues, bones, and internal organs.
• Neurosyphilis now most often seen w/ HIV, involves CNS, meninges,
vascular sxs w/ meningitis, CN palsies, tabes dorsalis
Secondary syphilis
Syphilis Dx
• Darkfield microscopy
• Nonspecific tests: rapid plasma reagin (RPR) and Venereal
Disease Research Laboratory (VDRL) used as screening
tests, reported as titer and followed for response to tx
• Specific treponemal tests: fluorescent treponemal antibody
absorption (FTA-ABS) assay and the
microhemaglutination assay (MHA-TP) used as
confirmatory tests
• False positive nonspecific and treponemal tests. FP
treponemal tests: SLE, HIV, ESLD, IVDU
• False negative occur prior to development of abs
Syphilis Tx
1. Primary, secondary or early latent (less than 1year)
-Benzathine PCN G 2.4million units IM x1
-PCN allergic, nonpregnant: doxycycline 100mg bid x14
days
-In pregnancy, PCN desensitization
2. Late latent, tertiary or unknown duration
-Benz PCN G, 2.4 million units IM q week x3 weeks
-PCN allergic: doxycycline 100mg bid x4 weeks
3. Neurosyphilis
-PCN G 3-4 million units IV q4hrs x10-14 days
Relevant question
• MKSAP 22
Actinomycosis
• Subacute-to-chronic infection caused by filamentous,
gram-positive, non-acid fast, anaerobic bacteria.
• Part of normal oral flora
• Infection is characterized by suppurative and
granulomatous inflammation with abscess and sinus tract
formation with sulfur granules
• Most often results in cervicofacial infection 50% cases
• Presents in pts predisposed to facial infection
- dential caries, gingivitis, tooth extractions
-underlying DM, immunosuppression, oral malignancies or
radiation
Actinomycosis
Antibiotic Ppx for endocarditis
• No longer indicated - bicuspid aortic valve, acquired aortic
or mitral valve disease (including MVP with regurgitation
and those who have undergone prior valve repair), and
hypertrophic cardiomyopathy with latent or resting
obstruction.
• Current recommendations –
– Prosthetic heart valves, including bioprosthetic and homograft
–
–
–
–
valves.
A prior history of IE.
Unrepaired cyanotic congenital heart disease, including palliative
shunts and conduits.
Completely repaired congenital heart defects with prosthetic
material or device, whether placed by surgery or by catheter
intervention, during the first six months after the procedure.
Repaired congenital heart disease with residual defects at the site
or adjacent to the site of the prosthetic device
Relevant question
• MKSAP Cardiology 32
Toxic Shock Syndrome
• Caused by S. aureas and group A strept
• Fever, n/v/diarrhea, rash, hypotension (latter
required for dx)
• Caused by exotoxins that act as superantigen (i.e.,
interact directly with MHCII on APC and
crosslink TCR -> massive cytokine release)
• Tx: Clindamycin (reduces toxin synthesis and
shedding) + Vanc, unless known MSSA
Botulism
• Caused by C. botulinum toxin, gram pos spore producing
rod
– Food borne: usually involving home canned fruit/veg or fish
– Wound – typically IVDU
– Infant - association with raw honey, but this is minor cause at best.
More likely environmental dust with C. botulinum spores
• Sx: cranial neuropathies with symm descending weakness.
Five D’s: diplopia, dysphonia, dysarthria, dysphagia,
descending paralysis
• Tx: supportive, including mechanical ventilation prn.
• Antitoxin: trivalent for adults, botulism immune globulin
for infants. Of note, pentavalent antitoxin available only
within the DoD.
• Abx: unproven, though PenG widely used in wound
botulism
Relevant question
• MKSAP 73
Traveler’s/Food borne Diarrhea
• Most is E coli, usually ETEC (remember HUS). E
coli usually self-limited
• Other bacterial pathogens
–
–
–
–
Salmonella – meat/poultry
Shigella – severe sx, salads/milk/dairy
Vibrio – shellfish
Campylobacter – poultry
• Viral
– Norwalk – cruise ship
– Rota – peds exposure
– Hep A
Relevant questions
• MKSAP 90, 97
OI ppx in HIV
• Pneumocystis – CD4 < 200
– Bactrim, dapsone, atovaquone
• Toxo – CD4 < 100
– Same as above
• MAC – CD4 < 50
– Azithro
Initiation of HAART
Clinical cat
CD4
VL
Tx recommendations
Aids def
illness
Asx
Any value Any value treat
<200
Any value treat
Asx
200-350
Asx
> 350
Any value Weigh
pros/cons
>100,000 ?
Asx
>350
<100,000
Defer tx
HIV-related questions
• MKSAP 111, 122, 20, 27, 7
The End
Natalie says, “Good luck on the boards, I’ll be at the beach.”