ID/Immunology Flashcards
Which bacterial infections can go transplacental?
Listeria
Syphilis
TB
What is timing for early onsent sepsis? Late onset?
EOS: first 72 hours (sometimes first 6 days)
Late: 7-90 days (may be later in preemie)
What has greater mortality, early or late sepsis?
Early - mortality 15-45%
Late - mortality 10-20%
What are top 2 causes of EOS? Late?
Early: 1. GBS 2. E coli
Late: 1. Staph epi 2. S aureus
What is the most common etiology for osteomyelitis in neonates? Most common site?
Hematogenous spread
Site (metaphysis): 1. Femur 2. Humerus
*usually multiple bones
What is most common bacteria im osteomyelitis?
Staph aureus (way less common… GBS, E coli) Of note: GBS osteo 3-4 wks, humerus
How long until xray findings in osteo? How many with pos bcx?
7-10 days
60% with positive bcx
What are most common organisms in omphalitis?
- S aureus
- Group A strep
Others: gram neg bacilli, anaerobes
Via direct invasion by skin
When does most meningitis occur? Most common organisms?
During first month of life (premature 10x risk)
Organisms: 1. GBS 2. E coli (K1 antigen) 3. Listeria
Do males or females get UTI more common in neonates? Which org?
Males
E coli (then Klebsiella, enterobacter)
Hematogenous or ascending, often anomalies
What does GBS look like on gram stain?
Gram positive diplococci in chains
Which GBS serotype causes most late onset sepsis?
Serotype III
Is there more meningitis in Early or late GBS infection?
Late: 30-40% meningitis
Early: 5-10%
Early is more often pna (35-55%) and sepsis (25-40%)
What is gram stain of Listeria? Sx?
Gram positive rod Granulomatous rash Placental microabscesses Inc risk of stillbirth/miscarriage Via transplacental route
How is congenital syphilis transmitted?
Transplacental (greater GA, greater risk of infection) Risk: Untreated primary - 70-100% Early latent - 40% *30-40% infected fetuses are stillborn
Sx of congenital syphilis?
2/3 asymptomatic Large placenta HSM Snuffles Wimberger sign (destruction of medial metaphysis tibia > humerus)
Will treponemal or non-treponemal be pos for life? What do they test for?
- Treponemal pos for life (FTA-ABS)
- Non-treponemal (RPR or VDRL) tests for cell membrane cardiolipin nonspecific IgG Ab, sign of response to host tissue damage, gives titer
Treponemal: detects specific Ab (IgG or IgM) to Treponema pallidum
What is appropriate response in maternal titers to syphilis tx?
Four fold decrease
What is gram stain for Neisseria gonorrheae?
Gram negative intracellular diplococci in pairs
What are sx of gonorrhea in neonate?
Most common: arthritis
Others: conjunctivitis, scalp abscess (fetal monitor), pna, sepsis
What type of growth medium do you need to culture gonrrhea?
Thayer-Martin growth medium (need to plate rapidly)
What is rx for gonorrhea in neonate?
If born to untreated mom: 1 IM CTX
Conjunctivitis: 1 IV CTX
Systemic: 7+ days cephalosporin
What does chlamydia look like on gram stain? What kind of stain is needed?
Gram negative cocci but Very hard to gram stain, obligate intracellular bacteria
Stain: Giemsa stain
What are sx of chlamydia pneumonia?
5-20% of pts with chlamydia, 4-12 weeks with staccato cough
70% have Eosinophilia (50% with hx of chlamydia conjunctivitis)
Can mother breatfeed on isoniazid?
Yes, it latent. Infant needs pyridoxine.
When should infant exposed to TB have PPD?
3-4 months (wont be positive before)
What do you use to treat neonate with TB?
Isoniazid RIF (turns body fluid orange) Pyrazinamide Aminoglycoside If meningitis: steroids (shown to reduce mortality and NDI)
What is gram stain and pathophysiology of botulism?
Anaerobe, gram positive bacillus
Toxin inhibits release of acetylcholine from nerves
Need human-derived botulinum antitoxin **dont give aminoglycosides (will make worse, inc neuromuscular blockade)
What is prognosis/recovery for botulism?
Several weeks, toxin binds irreversibly
What bacteria typically cause brain abscesses?
Citrobacter and Enterobacter
What disorder gives you an increased risk of E coli UTI?
Galactosemia
What antibiotic may be needed in gram neg that produce extended spectrum beta lactamases?
Meropenem
What is rate of neonatal hsv if genital lesions at delivery and primary hsv? Same but recurrent hsv? Which is more common?
Primary with lesions: 25-60% will be infected
Recurrent: <5%
*exposed to recurrent mothers more common, 50% of neonatal hsv born to secondary HSV mothers
>75% neonates w HSV asymptomatic mothers or without known hx (75% due to HSV2)
What is the common histology finding of hsv?
Multinucleated giant cells
Also: eosinophilic intranuclear inclusions vis Tzanck smear
What is most common presentation of neonatal HSV disease? Highest mortality? Worst outcome?
Common: Skin, eye, mucous mem (SEM) 40-45% (disseminated 20%, CNS 30-35%)
Mortality: Disseminated (30%) (minimal if SEM, and 4-10% CNS)
Outcome: CNS worst (30% normal), disseminated 30-80% normal, SEM >90% normal
What is length of treatment for hsv SEM, disseminated and CNS?
Acyclovir 14 days SEM
21 days CNS or disseminated
What is mechanism of action of acyclovir?
Inhibits viral DNA replication
Activated by thymidine kinase
What type lf virus is RSV? Which strain more common? Can transmit to fetus?
RSV is an RNA paramyxovirus
Strain A more common
Cannot transmit to fetus (no viremia)