Bacterial Infections of the CNS Flashcards
True or False: A major problem with spirochete infections is acquired antibiotic resistance
FALSE: spirochetes show little acquired antibiotic resistance
List the unique aspects of spirochetes
- Wide variety of transmission methods
- cross easily into blood stream
- primary virulence factors are for immune evasion
- diagnosis is challenging
- Jarisch-Herxheimer reaction
True or False: Borrelia are too small to see with standard microscopy
FALSE: borrelia are large enough to see with standard microscopy
What is the vector for B. burgdorferi?
Ixodes ticks
B. burgdorferi is stainable with what stain?
Giemsa, and silver
Lyme disease is transmitted primarily by _____ ticks during the ________.
1-nymph
2- summer
How long does it take for a tick to transmit Lyme disease?
24-48 hrs
Describe the three stages of lyme disease
Stage 1: Flu-like with erythema migrans rash
Stage 2: MSK and neuro sx, myocarditis, heart block, aseptic meningitis, Bell’s palsy (bilateral facial nerve palsy)
Stage 3: additional neuro sx, arthirits in large joints
After being treated for Lyme disease, what type of symptoms may persist?
fatigue, joint pain, mental status changes
How do you diagnose Lyme disease?
History of outdoor activity, season of activity, geographic location, serology may confirm exposure but not right away
How do you treat Lyme disease?
amoxicillin, doxycycline, alt: ceftriaxone, cefuroxime axetil for 10-30 days
What is the Jarisch-Herxheimer reaction?
flu-like sx 24 hrs after treatment, thishelps confirm the dx of lyme disease
When is prophylactic doxycycline for Lyme disease recommended?
in areas where the percentage of infected ticks is high, if someone has been bitten and the tick was in place for >24 hrs
When does Lyme disease cause high fever?
WHen there is a coinfection with erlichia or babesia
what are some characteristic symptoms caused by european ticks?
bluish borrelial lymphocytoma on earlobe or nipple
Acrodermatitic Chronica Atropicans
what is the vector for B. recurrentis?
body louse (seen in Africa and homeless shelters)
What is the vector for B. hermsii?
soft ticks (ornithodoros)
How many relapses typically occur with B. recurrentis? B. hermsii?
1 relapse in B. recurrentis (MORE SEVERE)
3 relapses in B. hermsii
What is the reservoir for B. recurrentis? B. hermsii?
B. recurrentis: HUMANS ONLY
B. hermsii: small mammals and ticks (more common in US)
Describe the pathogenesis of B. recurrentis and B. hermsii?
the borrelia immediately enter the blood stream from the bite site and multiply in many tissues–> malaise and organ dysfunction–> neutralizing Ab and IL-10 halt disease–> antigenic variation allows bacteria unrecognized by Ab to predominate –> disease resumes–> immune syst mounts a new response
How do you diagnose relapsing fever?
hx of tick bite or louse bite, fever chills headaches organ dysfunction peripheral blood smear: spirochetes usually visible during febrile periods
How do you treat relapsing fever?
tetracycline, doxycycline, erythromycin: peds, pregnant, nursing
What is the drawback of doing a culture for borrelia?
very slow 2-6 wks
What infection is characterized by multiple episodes of 3-5 days of high fever, with low BP and a well week in between episodes?
relapsing fever: B. recurrentis and B. hermsii
other sx: chills, arthralgias, N/V, mental status changes, nonproductve cough, diarrhea, dizziness, neck pain, photophobia, rash, dysuria
True or False: Leptospira are visible with standard microscopy
FALSE: leptospira are too small to see by standard microscopy, must use darkfield
What is another name for leptospirosis?
bilious typhoid
How is leptospirosis transmitted?
humans swimming in contaminated water (bacteria cross mucus membranes)
or
ingesting contaminated food/ drink
P2P is possible but rare
What are the two phases of leptospirosis?
phase 1: acute, 5-7 days high fever, rigor, headache, nausea - leptospira circulate in blood and multiply in blood vessel endothelium–> vasculitis, initial sepsis
phase 2: delayed/ immune - jaundice, renal failure, lung hemorrhage, aseptic meningitis, DIC, HUS, TTP, vasculitis
***both phases show conjunctival suffusion
How do you treat leptospirosis?
PCN G, alt: doxy, third-gen cephalosproins
Describe anicteric and icteric leptospirosis:
anicteric = normal course (biphasic) icteric= Weil Disease, increased mortality, phase 2 follows phase 1 more quickly
How do you diagnose leptospirosis?
history, serology, blood and urine cultures (usually neg), elevated BUN, creatinine, bilirubin, alk phos, serum CK
What are virulence factors of B. burgdorferi?
immune evasion: Lmp1
manganese transporter: BmtA
What are virulence factors of B. recurrentis and B. hermsii?
Complement resistance: HcpA
What are virulence factors of L. interrogans?
Hemolysis: SphH
Nephrotoxin: Loa22
What disease is caused by L. interrogans?
Leptospirosis
Is gram staining useful for spirochetes?
NO, they would be gram (-) but it doesn’t work
