Infectious Diseases Flashcards
How is HPV transmitted?
Direct epithelial-to-epithelial contact (sexually, vertically from mother to infant, oral mucosa)
Is HPV infection necessary before the development of cervical cancer?
Yes! However the infection must have been present for years
What type of cancers is HPV associated with?
Squamous cell carcinoma and adenocarcinomas of the cervix, penile / vulvar/vaginal cancers, squamous cell cancers of oropharynx
Which HPV serotypes are associated with most cancers?
HPV-16 and HPV-18
What are the other six HPV genotypes associated with the remaining 20% of cervical cancer?
HPV-31, -33, -35, -45, -52 and -58
Which HPV serotypes are associated with genital warts?
HPV-6 and HPV-11 are responsible for 90% of genital warts
What is the overall prevalence of HPV in canada?
11-29%, peak prevalence in young adults
What are risk factors for HPV infection?
of sexual partners, early age of first intercourse, never being married, never being pregnant, immunosuppression
Which serotypes does the quadrivalent HPV vaccine protect against?
HPV-6, -11, -16, -18
When should the HPV vaccine be given?
Before acquisition of the virus
What is the efficacy of the vaccine against the development of pre-cancer lesions?
> 98% (98% effective against dysplastic lesions, 100% effective against high-grade lesions, 99% effective against vaginal warts)
What is the vaccination schedule for the HPV vaccine?
Depends on age. If you are 9-14 yrs old and immunocompetent, you may receive 2-dose schedule (0 and 6-12 months). Otherwise, you should get 3-dose schedule (0,2,6 months).
Who does the CPS recommend receive the HPV vaccine?
Girls between 9-13 yrs of age, and all unimmunized females 13 yrs of age and older. Also: females who have had previous pap abnormalities or warts
What are the two vaccines approved in Canada for HPV?
Gardasil or Cervarix
What are infectious etiologies of genital ulcers?
- HSV
- syphilis (treponema pallidum)
- chancroid (h. ducreyi)
- lymphogranuloma venereum (chlamydia)
- granuloma inguinale (donovanosis)
- candida
- secondary bacterial infection
How do you treat first episode of HSV infection?
7-10 days of oral acyclovir (if immunocompetent)
What type of virus causes Measles?
Paramyxovirus
What are the symptoms of Measles?
- fever
- malaise
- cough
- coryza
- conjunctivitis
- maculopapular rash
- Koplik’s spots
What are some serious complications of measles?
- pneumonia
- encephalitis (1/1000 cases)
- death (2-3/1000 cases)
What is a rare long-term sequelae of measles infection?
subacute sclerosing panencephalitis (SSPE) - can occur 7-10 yrs after the primary infection
When is a person with measles infectious?
From 4 days before the rash until 4 days after the rash
What is the incubation period of the measles virus?
approx 14 days (range 7-21)
How many people die from measles each day (in the world)?
380!
What type of vaccine is available against measles?
live-attenuated (as part of the MMR)
What are recommendations for unvaccinated children who are travelling?
- children ages 6-11 months who travel internationally should receive one dose of the MMR vaccine 2 weeks before leaving
What type of isolation should someone with suspected measles have?
airborne precautions
What is the treatment of measles?
Supportive care! No anti-virals indicated. Severe cases can be treated with Vitamin A (age specific dosing)
What type of strep causes “strep throat”?
Group A streptococcus (GAS) aka streptococcus pyogenes
What type of bacteria is GAS?
gram positive coccus in chains
What is the reservoir of GAS?
skin and mucous membrane of human host
What are the suppurative complications of GAS pharyngitis?
♣ Necrotizing fasciitis ♣ Bacteremia ♣ Peritonsillar cellulitis / abscess ♣ Otitis media ♣ Sinusitis
What are the non-suppurative complications of GAS pharyngitis?
♣ Acute rhematic fever
♣ Post-strep glomerulonephritis
♣ Pediatric autoimmune neuropsychiatric disorders associated with strep (PANDAS)
Who gets GAS pharyngitis?
School aged children or their younger siblings
What are viral etiologies of acute pharyngitis?
- EBV
- HIV
- HSV
- influenza
- enterovirus
- adenovirus
What can you recommend to parents to prevent RSV?
- hand hygiene
- breastfeeding
- avoiding cigarette smoke exposure
- avoiding contact with sick individuals
What is used for RSV prophylaxis?
Palivizumab
How is palivizumab dosed?
15mg/kg administered IM Q30 days during RSV season (Max 5 doses)
What is a high-risk group for RSV related hospitalization?
Inuit children from remote northern communities
who does the CPS recommend palivizumab for?
- CHD or CLD (O2 need at 36 weeks GA) requiring diuretics, bronchodilators, steroids or supplemental O2
- born at < 30 wks GA and < 6 mos
- born at < 36 wks GA and < 6 mos and inuit/aboriginal
- term inuit/aboriginal and live in remote area
Do you treat a child who is asymptomatic but colonized with c.diff?
No
What is the recommended treatment for mild or moderate c.diff?
Metronidazole PO x 10-14 days
second line: vancomycin PO
What are the features of severe c.diff infection?
●Profuse diarrhea with systemic sxs (fever, rigors, severe abdo pain or distention) ●Hypotension / shock ●Ileus or toxic megacolon ●WBC >15 ●Elevated creatinine ●Serum albumin level
which antibiotic is most effective for treatment of c.diff?
vancomycin
but flagyl preferred for mild or moderate infections
What are complications of varicella infection?
- invasive group A strep soft tissue infection (cellulitis, myositis, nec fasc, TSS)
- neurologic complications (encephalitis, acute cerebellar ataxia)
- Reye syndrome
- pneumonia (uncommon in children)
- hepatitis
Definition of invasive GAS infection
- if there is lab confirmation of infection (isolation of GAS from a normally sterile site), invasive disease is defined as:
o Stretococcal TSS
o Soft tissue necrosis (myositis, gangrene)
o Meningitis
o Combination of all of the above
Who should receive chemoprophylaxis if exposed to someone with invasive GAS?
close contacts exposed over past week
What is the definition of close contact (in the context of invasive GAS chemoprophylaxis)
o Spent at least 4 hrs per day with the patient in the previous 7 days, or 20 hours per week
o Non household persons who share the same bed or have had sexual relations
o People who have had direct mucous membrane contact
o Injection drug users who shared needles
o Selected contacts in long-term facilities, child care, hospital settings
what is the differential diagnosis for croup?
- Bacterial tracheitis (if high fever, toxic appearance, poor response to epi)
- Epiglottitis (absence of barky cough, drooling, sitting forward in “sniffing position”)
- Foreign body
- RPA
- Angioedema
what is tamiflu?
a neuraminidase inhibitor (oseltamivir)
treatment of outpatient community acquired pneumonia
amoxicillin x 5 days
OR
azithromycin x 5 days (if suspect atypical)
treatment of inpatient CAP
ampicillin x 7-10 days (can upgrade to 3rd gen cephalosporin +/- vanco if severe)
How do you treat opthalmia neonatorum related to gonorrhea?
single dose of ceftriaxone
Who should receive UTI prophylaxis?
: antibiotic prophylaxis is NOT routinely recommended, but may be considered in grade IV or V VUR or significant urologic abnormality
what are the usual antibiotic choices for UTI prophylaxis?
septra or nitrofurantoin
If the child has a UTI resistant to septra or nitrofurantoin, what do you use for prophylaxis?
NOTHING. - Experience suggests that using broader-spectrum agents for prophylaxis (such as cefixime or ciprofloxacin) often results in a UTI with an organism that is resistant to any remaining oral options for therapy.
What are the types of maternal HSV?
Newly acquired:
-First-episode primary infection (mother has no serum antibodies to HSV-1 or -2 at onset);
- First-episode nonprimary infection (mother has a new infection with one HSV type in the presence of antibodies to the other type)
OR
Recurrent (mother has pre-existing antibodies to the HSV type that is isolated from the genital tract).
what is the impact of c-section on risk of maternally transmitted HSV?
Delivery by elective Cesarean section markedly reduces but does not eliminate the risk for newborn infection
how should a woman positive for HSV be treated during pregnancy?
prophylaxis with acyclovir from 36 weeks GA to delivery
How can perinatal HSV be classified?
- Disseminated HSV;
- Localized CNS HSV;
- Skin, eye and mucous membrane (SEM) infection.
When do symptoms of neonatal HSV infection present?
Can present up to 6 weeks after birth
How is neonatal HSV detected?
- viral cultures, PCR, direct immunofluorescent antibody staining of skin lesions, enzyme immunoassays for HSV antigens
How is neonatal HSV treated?
acyclovir 60 mg/kg/day in three divided doses administered every 8 h
What is the length of treatment for neonatal HSV?
Treatment duration should be 14 days if the disease is limited to the skin, eyes or mouth, and a minimum of 21 days if the infection involves the CNS or is disseminated.
What do you recommend to a mom with active HSV?
Mothers with herpes labialis should wear a disposable mask when caring for their infant
contraindications to the live-attenuated influenza vaccine (LAIV)
o pregnant o egg allergy o immunocompromised o hx of severe allergic reaction o receiving aspirin o 2-4 years old with asthma, hx of wheeze in past 12 months
what causes bullous impetigo?
strains of S. aureus that produce exfoliative toxin A, a toxin that causes loss of cell adhesion in the superficial epidermis by targeting the protein desmoglein 1 (similar to pathology of pemphigus)
what is ecthyma?
ulcerative form of impetigo in which the lesions extend through the epidermis and deep into the dermis. They consist of “punched-out” ulcers covered with yellow crust surrounded by raised violaceous margins (due to streptococcus pyogenes)
what bugs cause impetigo?
staph aureus, beta-hemolytic strep (primarily group A)
what causes lyme disease?
borrelia burgdorferi
what is erythema migrans?
Erythema migrans is the manifestation of early localized Lyme disease. Erythema migrans is a rash that appears at the site of the tick bite, usually within 7 to 14 days after the bite (range 3 to 30 days)
What is the treatment of choice for lyme disease?
If > 8 yrs = oral doxycycline, if under 8 yrs = oral amoxicillin or cefuroxime
How is hepatitis A transmitted?
fecal-oral
How do you diagnose hepatitis A?
Serum IgM anti-HAV is the gold standard
what is the best test for an infant born to an HIV-infected mother?
qualitative RNA assays, or PCR if not available
Who should receive VariZIG immunoprophylaxis after VZV exposure?
- Immunocompromised patients
- Newborns of mothers with varicella 5 days before or 2 days after delivery
- Preterm infants 28-36 weeks GA who are exposed, if their mother does not have immunity
- Preterm infants
How do you treat herpes zoster oticus?
Acyclovir and steroids
What is the other names for herpes zoster oticus?
Ramsey Hunt Syndrome
How do you manage tympanostomy tube ottorhea?
Uncomplicated cases are typically treated with topical antibiotic ear drops with or without corticosteroids
How long after IVIG do you give the DTaP vaccine?
As soon as indicated
Who do you need to give VZIG to?
- Immunocompromised patients
- Newborns of mothers with varicella 5 days before or 2 days after delivery
- Preterm infants 28-36 weeks GA who are exposed, if their mother does not have immunity
- Preterm infants
What common live vaccines? (5)
Intranasal influenza vaccine, MMR, varicella, BCG, rotavirus
How long should live vaccines be delayed after IVIG?
5-11 months (dependent upon the vaccine and dose of IVIG)
What type of isolation is necessary for Measles?
airborne
Diagnosis of Measles?
- Positive IgM antibodies
- Isolation of virus
- Rise of IgG
What causes cat scratch disease?
Bartonella henselae (bacteria)
What causes perinaud’s oculoglandular syndrome?
Bartonella henselae, a bacteria causing cat scratch disease. Symptoms = conjunctivitis in one eye, lymphadenopathy
Which bacteria has been found to contaminate powder based formula?
Enterobacter sakazaki
What is the risk of transmission of HIV in a blood transfusion?
1 in 10 million
What is the risk of transmission of HepC in a blood transfusion?
1 in 6 million
What is the risk of transmission of HepB in a blood transfusion?
1 in 1.5 million
What type of bacteria is Listeria?
Gram positive bacilli
Most common presentation of West Nile Virus?
Asymptomatic!
Diagnosis of congenital CMV?
urine or saliva sample within first three weeks of life - viral culture or PCR
Timeline for treatment of congenital CMV?
Antivirals only benefit within first month of life
Which anti-TB drug is associated with oculo-toxicity?
ethambutol
What serology indicates active HepB infection?
HBsAg, HBeAg
What antibody develops after HepB immunization?
Anti-HBs (surface)
Duke criteria for endocarditis
Major:
- 2 positive blood cultures
- endocarditis on ECHO
Minor:
- fever
- embolic-vascular signs
- immune complex phenomena (GN, arthritis, RF, osler nodes, roth spots)
- single positive blood culture
- soft ECHO signs
- predisposing conditions
Can have 2 major, one major + 3 minor, or 5 minor
bugs implicated in endocarditis
- strep viridans
- staph aureus
HPV types that gardasil protects against
6, 11, 16, 18
what pathogens must be considered in meningitis in the unimmunized child?
strep pneumo, haemophilus influenzae
what are the 5 serogroups implicated in neisseria meningitis infections?
A, B, C, Y, W-135
which serogroup is the most common cause of meningoccal infection in canada?
B
what groups are at increased risk of meningococcal meningitis?
- anatomical or functional asplenia (HbSS)
- primary antibody deficiency disorder
- complement, properdin, factor D deficiency
- travelling to a place where there is a high meningococcal risk
- lab personnel with exposure to meningococcus
- military
as per CPS, when should canadian children be immunized against neisseria meningitidis?
Children should be immunized with MCV-C (polysaccharide vaccine) at 12 months of age
Treatment of congenital syphilis
IV penicillin 10-14 days
CSF findings toxoplasmosis
lymphocytic pleocytosis and very high CSF protein
classic triad of toxoplasmosis
hydrocephalus, cerebral calcifications, chorioretinitis
what is the upper limit of time that you can give VZIG after an exposure?
10 days
classic triad for rubella?
cataracts, PDA, sensorineural hearing loss
what do you do for a documented maternal exposure to parvovirus B19?
obtain maternal serology (IgM, IgG). if negative, repeat in 2-3 weeks
GBS positive mom, mild penicillin allergy. what intrapartum prophy?
cefazolin
GBS positive mom, severe penicillin allergy. what intrapartum prophy?
clindamycin
treatment of skin, eye, mouth HSV in neonate?
acyclovir 60 mg/kg/day x 2 weeks
treatment of disseminated / CNS HSV?
acyclovir 60 mg/kg/day x 3 weeks AND oral acyclovir x 6 months
treatment of latent TB Infection
isoniazid x 9 months
What serologies do you test for in needle-stick injuries?
serology for hep B, hep C, and HIV
when do you do bloodwork after a needle-stick injury?
baseline, 6 weeks, 3 months, 6 months
which vaccines do you have to delay after IVIG?
MMR and VZV
Toxoplasmosis triad
hydrocephalus, chorioretinitis, cerebral calcificiations
toxoplasmosis - CSF findings
lymphocytic pleocytosis, elevated protein
most common neurologic manifestation of Lyme
facial nerve palsy
treatment of Lyme in child < 8yrs old
amoxicillin OR cefuroxime
Most common clinical symptom of west nile virus
asymptomatic
Neurologic symptoms of west nile virus
aseptic meningitis, encephalitis, acute flaccid paralysis
Post-bite (breaking the skin) - when to check serology for Hep B, Hep C and HIV?
Hep B: 6 months
Hep C: 6 months
HIV: 6 weeks, 3 months, 6 months
When to prophylax needle stick injury?
If fresh blood, blood injected and < 72 hrs since needle stick occurred = HIGH RISK, should have 3 drug prophylaxis (AZT) x 28 days
(low risk: consider 2 drug prophylaxis)
Side effects of AZT
nausea, vomiting, abdo pain, diarrhea, anorexia
mild neutropenia, anemia
elevated liver enzymes
Members of flavivirus family
Zika West Nile Dengue Japanese encephalitis St. Louis encephalitis Yellow fever
Congenital Zika Syndrome - features
o Severe microcephaly w/ collapsed skull, redundant scalp
o Thin cerebral cortices, subcortical calcifications
o Macular scarring, focal pigmentary retinal mottling
o Contractures, arthrogryposis
Zika virus - diagnosis
o Serology (IgM or IgG or neutralizing antibody)
OR
o Detection of ZIKV RNA by PCR
How would you work up suspected Congenital Zika Syndrome?
- Serology and PCR on blood and urine of mother and infant
- U/S and MRI brain for infant (non-urgent)
- Save placenta
What anti-fungal medication would you use for invasive aspergillosus?
Voriconazole
Risk factor for invasive group A strep in children
Varicella infection
Signs of invasive GAS infection
TSS
Soft tissue necrosis (nec fasc)
Meningitis
Treatment of invasive GAS
Penicillin
Clindamycin
Chemoprophylaxis of GAS
1st generation cephalosporin (keflex)
Conditions that need prophylaxis for IE
o Prosthetic cardiac valve or previous IE
o Congenital heart disease – unrepaired cyanotic, repaired in last 6 mos, repaired with leak/defect
o Cardiac transplant recipients with valvulopathy
How do you test for syphilis?
Non-treponemal test (RPR)
and treponemal test
What do you monitor if you are treating for syphilis?
RPR (want a fourfold drop in titre at 6 mos)
What is a “barbershop pole” umbilical cord associated with?
Congenital syphilis
Signs of congenital syphilis at birth
Rhinitis / snuffles, neurosyphilis, anemia/thrombocytopenia, necrotizing funisitis (‘barbershop pole’ umbilical cord)
Signs of congenital syphilis within first 8 weeks of life
Hepatosplenomegaly
Rash
Tooth abnormalities in congenital syphilis
o 13-19 mos: Mulberry molars
o Permanent teeth – Hutchinson’s teeth (widely spaced, notched)
MSK anomalies in Congenital Syphilis
Osteochondritis, pseudoparalysis, frontal bossing, saddle nose, winged scapula, sabre shins, Clutton’s joints (recurrent arthropathy, painless knees effusions)
Which organism causes tinea versicolor
Malassezia
What should you use to treat tinea capitis?
Terbinafine
Itraconazole is also good, but not first choice
What are the vector + host of West Nile Virus?
Culex mosquitoes (vectors) Birds (hosts)
Complications of West Nile Virus
Encephalitis, meningitis
Flaccid paralysis
Risk of Reye’s syndrome with which two viruses (and ASA)
Influenza
VZV
The HPV vaccine prevents… (4 things)
- Warts
- Adenocarcinoma - cervical cancer
- Squamous cell cancers - penile, vaginal, oropharyngeal
- Recurrent respiratory papillomatosis
Gram negative rod in returning traveller….
Salmonella typhi!
Tx: ceftriaxone or ciprofloxacin
