Infectious Disease Flashcards
How does the tetanus vaccine work?
- inactivated toxin
The tetanus toxoid is an FDA-approved vaccination given alone or in conjunction with other vaccines. It is protective against effects from a gram-positive bacillus, Clostridium tetani.
This bacteria produces a neurotoxin called tetanospasmin, which blocks the release of an inhibitory neurotransmitter and leads to unopposed muscle contractions and spasms.
Vaccinations exert their effect on the human body via priming the active immune system. Following the administration of the tetanus toxoid, the immune system is stimulated and responds to the antigens present in the vaccine.
Preparation of the tetanus toxoid is via inactivation of the toxigenic strains of Clostridium tetani. The toxic strains are grown in liquid media, purified, and then treated with formaldehyde to take away the pathogenic properties.
AOM Diagnostic criteria CPS
DIAGNOSTIC CRITERIA:
1.Acute onset symptoms (otalgia or suspected otalgia)
2.Middle ear fluid (loss of mvmt, loss of bony landmarks, air fluid level) and significant inflammation of middle ear
- decrease in TM mobility (as visualized with a pneumatic otoscope) has good sensitivity and specificity for MEE
*Bulging TM esp if yellow or hemorrhagic has high sensitivity for bacterial origin
*Perforation with purulent discharge also indicates bacterial cause
AOM antibiotics
AMOXICILLIN
<2y = 10d (or perforated TM)
>2y = 5d
TID: 45-60mg/kg/day
BID:75-100mg/kg/day required
*consider other antibiotics first line:
-Otitis-conjunctivitis syndrome: Hflu/Moraxella more common -> amox clav or second gen cephalosporin
-Recent tx w/ amox in 30d or relapse of current infx -> amox clav
Varicella complications
- varicella pneumonia
- varicella encephalitis
Lice Management and counselling
KIDS WITH LICE CAN GO TO SCHOOL
TREAT LICE WITH PERMETHRIN
Head lice infestations are not associated with disease spread or poor hygiene
Head lice infestations can be asymptomatic for weeks.
Diagnosis requires detection of live head lice. Nits do not indicate active infestation.
Environmental cleaning/ disinfection not warranted. Head lice or nits do not survive for long away from the scalp.
Treatment with topical head lice insecticide (two applications 7 to 10 days apart) is recommended for active infestation
When there is evidence of treatment failure—detection of live lice—using a full course of topical treatment from a different class of medication is recommended.
The scalp may be itchy after applying a topical insecticide but itching does not indicate treatment resistance or a reinfestation.
Topical insecticides can be toxic. Take care to avoid unnecessary exposure and, when indicated, minimize skin contact beyond the scalp.
Excluding children with nits or live lice from school or child care has no rational medical basis and is not recommended.
For children ≥2 months of age, permethrin and pyethrins are acceptable treatments for confirmed cases of head lice. Dimethicone can be used in children ≥2 years of age.
Myristate/ST-cyclomethicone (Resultz) can be used in children ≥4 years of age. Benzoyl alcohol lotion is comparatively expensive but can be used in children ≥6 months of age.
6yoF returned from to to Nova Scotia with family. Has erythematous rash with red centre and concentric ring around it. Also with fever, malaise, arthralgias. What is your management?
Start doxy for lyme disease now
Early, cutaneous disease is a clinical diagnosis. Treatment = doxycycline 10d
Dog bite bugs
Pasturella, Staph aureus, Strep, Anaerobes
Dog bite management
- tetanus
- maybe rabies
- amox clav if:
- Puncture wound
- Hands, genitalia, face, joints
- Wounds requiring closure
Up to how many weeks after birth is a neonate at risk of becoming ill with a perinatally acquired HSV infection?
6 weeks
Duration of treatment for neonatal HSV
SEM disease 14 days
Disseminated or CNS disease 21 days
–> For infants with CNS disease, CSF should be sampled near the end of a 21-day course of therapy. If the PCR remains positive, treatment should be extended with weekly CSF sampling and ACV stopped when a negative result is obtained.
Criteria staph toxic shock
Criteria (all 6 required):
Fever 38.9 or higher
Diffuse macular erythroderma
Desquamation 1-2 weeks after onset, particularly on palms/soles
Hypotension (systolic < 5%ile), orthostatic changes > 15 mmHg, or orthostatic syncope or dizziness
Involvement of 3 or more organ systems: GI, MSK, mucous membrane, renal, hepatic, hematologic, or neurologic
Negative blood, throat, or CSF cultures for alternate pathogens (blood cultures may be positive for staph aureus) and/or negative titres for rocky mountain spotted fever, leptospirosis or measles
Typhoid fever (presentation, w/u ,tx)
+/- diarrhea, fever in returning traveller
typically SEA/India
get a blood culture (but only~50% sensitive)
Tx: ceftriaxone (if from Pakistan, there is high ctx resistance so use meropenem)
malaria test
thick and thin smears
Severe malaria (clinical manifestations and laboratory measures)
Clinical:
- unable to walk
- impaired consciousness
- resp distress
- multiple convulsions
- shock
- DIC
- Jaundice
Labs
5% parasitemia typically
Hb <70
Acidosis
AKI
High lactate
malaria treatment
mild: malarone (Atovaquone-Proguanil)
Severe: artesunate
fever of unknown origin definition
duration > 2 weeks with uncertain diagnosis despite appropriate initial investigations
baratonella henselae
cat scatch disease
Q: unilateral swollen lymph nodes, impsilateral conjunctivitis, enlarged spleen. no atypical lymphocytes on smear
Treatment: azthromycin x 5d
cat scratch treatment
azithromycin
chronically draining cervical lymph node in 4year old - most likely pathogen
atypical mycobacterium
features
- young age, no fever, unilateral LN, no TB exposure, no cat exposure, chronic
ddx infections acute unilateral lymphadenopathy
Acute Bacterial Adenitis: staph aureus or strep pyogenes
Non-TB Mycobacterial Adenitis (Chronic)
chronic infection’s unilateral lymphadenopathy ddx
non tuberculous mycobacteria (MAC)
tuberculosis
bartonella
tularemia
chronic infections bilateral lymphadenopathy ddx
EBV, CMV, HIV, toxoplasmosis
perineud oculoglandular syndrome
bartonella with eye involvement
acute infection EBV lab tests
mono spot positive
VCA IgM +
EA IgG +
VCA IgG +
EBNA IgG + is remote past infxn
mono sports avoidance
risk splenic rupture
highest risk first 3 weeks for infection
return to sport once resolution of symptoms, normal labs and splenomegaly resolved
congenital infxn with rash on palms and soles
syphillis
congenital syphilis clues
persistent nasal discharge (esp bloody) - snuffles
rash on palms and soles
desquamating rash
pain with movement (pseudoparalysis) suggesting bony involvement
congenital syphilis precautions for health care workers
high risk of transmission through touching the skin!! contact precautions when handling baby
syphilis testing
treponemal tests (more sensitive and specific)
- CMIA, CLIA, TPPA, FTA ABS
- typically the screening test
Non treponemal tests
- RPR (serum), VDRL (CSF)
- quantitative titer
Syphilis RPR drop for adequate treatment
4 fold drop
divide the RPR number by 4
Ex. 1:64 –> 1:16
treatment for baby with congenital syphilis
IV penicillin x 10 days
full workup: Long bone XR, CSF, ab titers, labs (LFTs)
inadequate maternal treatment of syphilis
- non-penicillin regiment
- treated within 30 days of baby’s delivery
- less than 4 fold trop in titer
- no documentation of treatment
- mother had relapse or reinfection
Managment of baby born of mom with syphilis with adequate treatment
test the baby’s RPR and TT at 0,3,6 and 18mo and if negative, no further w/u needed. Baby should have drop in RPR by 3 mo and non reactive by 6 mo if they do not have syphilis.
If +RPR at 6 mo -> TREAT
CNS syphilis in neonate management
no change in abx (10 days IV penicillin)
rpt LP in 6 months
approach to possible zika virus exposure
mother with possible zika exposure in pgegnancy
- test maternal zika virus serology first
- if positive, chehck baby serology and PCR and head US
unexplained microcephaly + maternal history of travel or paternal history of travel
- zika serology mom then baby
Clinical features of congenital CMV
IUGR, microcephaly, rash (petechial), chorioretinitis, HSM, SNHL
10% of asymptomatic infants go onto have symptoms later (hearing loss)
Laboratory features of congenital CMV
Low platelets
Increased ALT
Conjugated hyperbili
Risk Factors for cCMV (who to test)
- Fetal US with findings suggestive of CMV (microcephaly, IUGR, periventricular calcifications)
- HIV exposure
- Primary immunodeficiency
- Babies who fail the newborn hearing screen
HUS finding in congenital CMV
periventricular calcifications
gold standard test for congenital CMV
urine PCR within 3 weeks of age
If CMV + newborn, what other investigations do you need to send?
- CBC
- Bili
- Liver enzymes
- HUS if normal neuro exam (MR if abnormal neuro exam)
- Hearing eval
- Optho eval
** DO NOT NEED TO SEND CSF UNLESS SZ OR SEPTIC
treatment for CMV
valganciclovir for 6 mo
can use IV ganciclovir if very unwell child
indications for CMV treatment
- CNS disease
- chorioretinitis (Severe disease)
- severe single system
- multisystem 3+ systems
How frequently do children with cCMV need their hearing checked?
every 1 yr until school age
testing options for congenital toxoplasmosis
serum serology
PCR on CSF, blood or urine
placental pathology
findings of toxoplasmosis on CSF
lymphocytic pleocytosis
very high protein (can cause obstructive hydrocephalus)
toxoplasmosis triad
-hydrocephalus (may have macrocephaly)
-Cerebral calcifications (parenchymal)
-chorioretinitis
congenital varicella syndrome
hypoplastic limbs
scarred skin, dermatomal scars
micropthalmia
typically d/t varicella in 1st or 2nd trimester
pregnant woman exposed to chicken pox
if no definitive history of chickenpox, check mom’s serology
- if IgG postive, no further intervention (she has had infxn previously)
- if IgG NEGATIVE, given VZIG within 10 days of exposure and treat with acyclovir if rash revelops
congenital cataract most likely cause
rubella
classic rash in congenital rubella
blueberry muffin rash due to extramedullary hematopoeisis, often palpable
classic rubella triad
cataracts
cardiac (PDA)
SNHL
diagnosis congenital rubella
rubella specific IgM prior to 3 mo of age
can also do PCR in NP swab or urine
parvo B19 pearls
slapped cheeks
can cause aplastic anemia
can cause congenital infxn if pregnant woman resulting in hydrops - if exposed, the mom should get serology for parvo (IgM neg, IgG positive is protective)
adequate GBS abx prophylais
at least 1 dose 4 hour before delivery
amoxicillin or penicillin
cefazolin is used for penicillin allergy
gram positive cocci in clusters
staph aureus (or cons)
antibiotics for sepsis < 28 days
amp + gent
workup for HSV in neonate
any signs of HSV - do full wokrup including LP and start acyclovir
HSV PCR of vesicle, NP, eyes, urine, stool, blood and csf
do LP ieven if clinically well!
most common manifestation is skin/eyes/mouth with vesicular lesion
SEM = 14 days
CNS = 21 days
duration treatment for HSV in neonate
IV acyclovir only
- isolated SEM: 2 weeks
- disseminated or CNS: 3 weeks
must repeat the LP before stopping treatment
*suppressive oral acyclovir for 6 months if CNS disease
*consider suppressive oral acyclovir for other disease - should offer to parents for SEM disease
maternal recurrent HSV with lesion at pregnancy
surface swabs for baby at 24hr, no treatment pending results because you know this is recurrent disease for mom
management of well appearing, asymptomatic infant possibly exposed to HSV during delivery
moms first episode with membrane rupture (c/s or vaginal delivery)
- empiric acyclovir
- swabs at 24hr
- if negative: 10 days
- if positive: 14-21 days of acyclovir
moms first episode, no ROM, dry C/S
- no empiric acyclovir
- swab baby
- if swab positive, full work up and treat
recurrent episodes
- no empiric acyclovir
- 24 hr swab, if positive, full work up and treat
Treatment of mild C diff (<4 stools per day)
Stop precipitating abx and reassess in 48hr
classic rash in lyme disease
erythema migrans (large target)
