Infectious Disease Flashcards
MC site of osteo
METAPHYSIS (can spread to epiphysis since blood supply intact until 8-18 months)
femur>humerus>tibia>radius>maxilla
neonates often with multiple bone involvement
Chemical conjunctivitis
within 24 hours of exposure
following erythromycin prophylaxxis
negative culture
spontaneously resolves within 48 hours
acute purulent conjunctivitis
24-48 hours of age
staph (MC)- golden crust around eyelids
GBS, H. flu, strep pneumo, pseudomonas
Neisseria gonorrhoeae conjunctivitis
2-5 days of life
ABRUPT onset of EXTREMELY COPIOUS, PURULENT bilateral discharge
MEDICAL EMERGENCY- progress to involve cornea and ulceration/perforation
Tx: 3rd gen cephalosporin IV (ceftriazone)
Chlamydia conjunctivitis
5-14 days of life
MC cause of conjunctivitis in 1st month of life
watery discharge that becomes purulent
often associated with chlamydial pneumonia
DX: Giemsa-stain of conjunctival scrapings
Tx: oral erythromycin x 14 days (20% require 2nd course)
erytho ointment does not completely prevent this
HSV conjunctivitis
BROAD range- 4 days to 3 wks
MC viral etiology
symptoms: keratitis, chorioretinitis, retinal dysplasia
yellow-white exudates, retinal necrosis
assess for systemic herpes and herpes encephalitis
Chorioretinitis:
1. early congenital syphilis
2. HSV
3. rubella
4. CMV
5. toxo
6. candidiasis
- salt and pepper appearance to fundus
- yellow white exudates, retinal necrosis
- salt and pepper appearance to fundus, unilateral/bilateral diffuse granular pigmented areas
- yellow white fluffy retinal lesions, hemorrhage
- necrotizing retinitis –> large atrophic retinal scars that involve macula
- fluffy white balls
Congenital syphilis
Intrauterine infection: majority acquired by hematogenous route, incr risk of NI hydrops, IUGR, increased risk preterm birth
unexplained large placenta
snuffles infectious until > 24 hrs of tx
HSV
yellow-white exudates and retinal necrosis
Candidal chorioretinitis
white fluffy balls
CMV chorioretinitis
yellow-white fluffy retinal lesions, hemorrhage present
Toxoplasmosis
necrotizing retinitis
Antibiotic to treat following GI bugs:
1. Salmonella
2. Shigella
3. Campylobacter/Yersinia
4. C.dif
- Cefotaxime
- Ampicillin
- Erythromycin
- Vancomycin
Has intrapartum antibiotic prophylaxis changed incidence of late-onset GBS??
NO
HAS ONLY DECREASED EARLY-ONSET DISEASE RATES
Incidence of early onset and late onset GBS disease
Early:
< 7 days of life
sepsis 25-40%
pneumonia 35-55%
meningitis 5-10%
Serotype III
Mortality: 5-10%
Late:
> 7 days of life
meningitis 30-40%
sepsis 70%
neurologic sequelae 50%
osteo (humerus MC site) or septic arthritis (hip MC site)
Serotype III
Mortality: 2-6%
Syphilis retinitis
salt and pepper fundus
Congenital syphilis:
Treponemal vs. non-treponemal test
Treponemal:
used for estabishing presumptive diagnosis
TFA-ABS = fluorescent treponemal antibody absorption: detects specific Ab (IgG, IgM) to treponema pallidum
reactive for life even after successful treatment
antibody titers DO NOT correlate with disease activity
Non-treponemal:
used for screening, assessing response to treatment, determining reinfection
VDRL/RPR: detects a cell membrane cardiolipid nonspecific IgG Ab- sign of response to host tissue damage
becomes negative 2 years after treatment
titers CORRELATE with disease activity
Neonate positive = titer 4xx high than maternal (neonate 1:32, mom 1:8)
Can be false positive (autoimmune, viral infections, endocarditis, passively transferred maternal IgG antibody to neonate) or false negative
EEG finding in disemminated HSV disease
spike and slow-wave activity in temporal region
Neonatal neisseria gonorrhoeae
Gram negative intracellular diplococci
Vertical transmission: vaginal secretions, breastmilk
conjunctivitis: purulent, 2-5 days after birth, profuse bilateral purulent discharge- EMERGENCY
scalp abscess from fetal scalp monitor
arthritis, pneumonia, sepsis, osteo, meningitis
Dx: conjunctival, blood, skin lesion, CSF gram stin/culture using THAYER-MARTIN medium
Disemminated dx: ceftriazone IV/IM (cefotax if hyperbili) xx 7 days, meningitis = 10-14
Eval for chlamydia- add erythro if needed
Association with syphilis and HIV
Follow up for treated neonate for syphilis
VDRL at 2, 4, 6, 12 mo until nonreactive or dec by 4-fold (dec by 3 mo, NR by 6 mo)
If increasing/persistent titers at 6-12 mo–> re-evaluate with LP, 10 days PCN
If initially abnormal LP–> monitor Q6 mo with exam/LP until LP normal
Types of penicillin for syphilis tx
Aqueous PCN G: IV, dose based on age, x 10 days
Procain PCN G: IM, single daily dose xx 10 days, CSF entry not as good as aqueous
Benzathine PCN G: IM, 1 dose, long acting, poor entry into CSF, not for active syphilis
Chlamydia
Obligate intracellular bacteria
Conjunctivitis and pneumonia- stoccato cough, nasopharyngitis, eosinophilia 70%
Dx: Giemsa stain culture of conjunctiva scrapings, nasopharynx, pneumonia- incr chlamydia specific IgM levels
Tx: oral erythro x 14 days
NOT detectable by gram stain
remember association of erythro with pyloric stenosis
Mycobacterium tuberculosis
Acid-fast bacilus
Congenital: hematogensou from infected placenta, aspiration/ingestion infected fluid
Postnatally acquired: inhalation of infected resp secretions, contamination of traumatized mucous membranes or skin
Present 2nd-3rd week of life
Non-specific sx: HSM, respiratory distress, fever, LAD
Congenital TB treatment: 4 drug regimen- INH, RIF, pyrazinamide, aminoglycoside- + steroids if meningitis
Clostridium tetani
Gram positive vacillus
Tetanus toxin binds to neuromusclar junction and blocks GABA release
usually due to improper umilical cord handling
Tx: supportive, tetanus IG to neutralize circulating unbound toxin
IV penicillinG 10-14 days
Bordetella pertussis
Gram negative pleomorphic bacillus
Presentation: mild URI (catarrhal stage) that progresses to paroxysmal cough
Dx: culture resp secretions with BORDET-GENGOU medium, PCR assay, lymphocotosis
Tx: oral erythromycin
remember association of pyloric stenosis and erythromcyin
Hep B serology
Unknown maternal Hep B status
> 2000g:
- Give Hep B vaccine within 12 hours
- Have 7 DAYS to find out results and then give HBIG
- needs 2 additional doses of Hep B vaccine
< 2000g:
- Give Hep B vaccine within 12 hours
- Have 12 HOURS to find out results then give HBIG
- needs 3 additional doses of Hep B vaccine
Parvovirus B19
Single stranded DNA
Fifth disease = erythema infectiosum: malaise, low grade fever, slapped-cheek rash
Fetal infection: increased risk of fetal loss, aplastic anemia (low reticulocytosis) and CHF–> hydrops
Titers with highest risk to fetus:
negative IgG, positive IgM = acute infection
Varicella
DNA herpes virus
Dx: Tzanck smear- multinucleated giant cells, PCR (most sensitive) of vesicular fluid, saliva
HIGHEST RISK OF NEONATAL TRANSMISSION: 5 days before delivery until 2 days post delivery- insufficient time for protective antibodies
Neonatal disease: cutaneous lesions, limb abnormalities (atrophy, distal to cutaneous lesions), eye (cataracts, chorioretinitis), severe mental deficiency, seizures, intracranial calcifications
VariZIG:
- infant with mother who develops varicella < 5 days from delivery –> 2 days after
- Preterm infant < 28 wks or </= 1000g significant exposure
- infant exposed postnatally 2-7 days- consider especially if preterm
Rubella
Transmission: U shaped curve (highest risk in beginning and end of pregnancy)
Presentation:
In-utero: hydrops
Congenital: sensorineural hearing loss, salt and pepper chorioretinitis, cataracts, blueberry muffin rash, PDA> PPAS, celery stalking of long bones
Classic triad: ears, heart, eyes
Late onset: continued hearing loss, intellectual disability, DM, thyroid dysfunction, progressive panencephalitis
Dx: viral culture nasopharynx, blood, urine, Rubella IgM/IgG
Supportive treatment
Screenings: hearing, eye exam, assess for heart disease
contact isolation from other newborns x 1 year unless 2 negative cultures
Echovirus
Type of enterovirus- single stranded RNA virus
Type 11: sepsis-like illness, hepatic necrosis, coagulopathy
Often fatal
Toxoplasmosis
Protozoal organism
Poorly cooked meat, cat feces
Transmission during pregnancy greater with increasing gestational age
- acquired early in pregnant = greater risk of severe disease
ASYMPTOMATIC: 70-90% at birth
SYMPTOMATIC: chorioretinitis, cortical brain calcifications, hydrocephalus, blueberry muffin rash, microcephaly, hearing loss
Eval: eye exam, hearing test, neuro exam, brain imaging
Pleocytosis on CSF
CMV
Double stranded herpes DNA virus- intranuclear and cytoplasmic inclusions
MC intrauterine infection worldwide
If maternal infection during 1st 20 weeks = greater risk of neonatal disease and severity of neonatal illness
ASYMPTOMATIC at birth: 85-90%; increased risk of hearing loss that correlated with presence of PERIVENTRICULAR calcifications, chorioretinitis
SYMPTOMATIC at birth: 10-15%; IUGR, HSM, blueberry muffin rash, thrombocytopenia, microcepaly, PERIVENTRICULAR calcifications, chorioretinitis, sensorineural hearing loss, seizures, long term neurologic sequelae
Tx: symptomatic congenital CMV disease = oral valgancyclovir x 6 months
can be acquired through breastmilk- incr risk in preterm infant
Treatment for congenital HSV
IV acyclovir for 14 days for SEM disease, 21 days if CNS involvement, 21 days for disseminated disease
oral acyclovir x 6 months to improve neurodevelopmental outcomes
Components of BM that target infections
- Lactoferrin: high amounts in BM, bacteriostatic against numerous bacteria
- Lactoperoxidase: low amounts in BM, requires hydrogen peroxide and thiocyanate for antibacterial effect
Infections that can cross breast milk
- CMV
- HIV
- Hep B- little risk of transmission especially if infant received vaccine and IVIG
- Rubella
- HSV
Contraindications to breastfeeding
- Maternal HIV
- Maternal HSV lesion on breast- can feed on non-affected breast
- Symptomatic mother with positive PPD and CXR (presumed active TB)
- Active breast abscess
Stain for Chlamydia
Giemsa-stein
Growth medium for Neisseria gonorrhoeae
Thayer-Martin
MUST PLATE FAST!
Growth medium for pertussis
Bordet-Gengou
Pseudomonas aeuginosa
Oxidase-positive
Catalase-positive
Rubella
Hemagglutination inhibition
Bactericidal
Completely destroy bacteria
Ideal for:
- endocarditis
- meningitis
- severe Staph and gram negative infection
Ex: penicillins, cephalosporins, aminoglycosides, vancomycin, quinolones
Bacteriostatic
Inhibit growth and reproduction of bacteria
Ex: erythroycin, clindamycin, chloramphenicol, tetracycline, sulfonamides
MIC
Minimal inhibitory concentration
measures degree of antibiotic activity against a specific organism
- lowest antibiotic concentration that completely inhibits IN VITRO visible growth of the organism
- correlates with potency of antibiotic
- DOES NOT suggest time period for antimicrobial activity
MBC
minimal bactericidal concentration
concentration of the antibiotic that kills the organism
- lowest antibiotic concentration that reduces growth by 99.9%
- bactericidal antibiotics MBC = MIC
- bacteriostatic antibiotics MBC > MIC
Classic triad: skin lesions, brain abnormalities, occular findings
Congenital HSV
Organisms most commonly associated with intrapartum infections
Ureaplasma urealyticum
Mycoplasma hominis
GBS serotype associated with meningitis
III
Wimberger sign
bilateral focal destruction of the medial aspect, proximal tibial metaphysis
in congenital SYPHILIS
HBIG and Hep B vaccine if maternal testing positive/unknown
< 2 kg: give HBIG AND HEP B vaccine < 12 hours of birth
> 2 kg: give Hep B vaccine imediately and can wait on HBIG up to 7 days of life
anti-hep b core
consistent with immunity due to natural infection
pinpoint yellow-white nodules on the umbilical cord with subamniotic microabscesses
congenital cutaneous candidiasis
tx with amphotericin B and cover for STAPH (amp/gent)
no fluc unless sensitivities are known
