Infectious Disease Flashcards
1
Q
What is the vertical transmission rate of HIV in treated vs. Untreated mothers?
A
1% vs. Up to 25%
2
Q
What are the areas worldwide endemic for: 1. Malaria, 2. Typhoid fever and 3. Dengue fever
A
- Malaria: Africa (highest)
- Typhoid fever: Southeast Asia, South and Central America, Africa, Eastern Europe, Indian subcontinant
- Dengue: southeast Asian (especially Thailand) and south Pacific, Central America and Caribbean
3
Q
What is it called when Bartonella henselae causes a unilateral conjunctivitis and preauricular lymphadenopathy?
A
Parinaud oculoglandular syndrome
4
Q
What are findings on the FSWU in neonates that may indicate a listeria infection?
A
High blood / CSF monicytes ans lymphocytes
5
Q
What are the daycare exclusiom rules for the following pathogens: impetigo, strep pharyngitis, pertussis, e coli 0157:H7, shigellosis, non-typhi salmonella, c diff, typhoid fever, hep A, chicken pox, mumps, measles, scabies
A
6
Q
What is the classic triad for congenital rubella?
A
Cataracts, PDA, SNHL
Other manifestations:
-early: LBW, HSM, blueberry muffin rash, hemolytic anemia, bony lucencies
-permanent: SNHL, cataracts, microphthalmia, salt and pepper retinitis, cardiac (PDA, PPS, VSD, myocarditis), GDD, behavioural issues, seizures
7
Q
When would you consider doing a repeat LP 24-36h after starting therapy in chikdren with bacterial meningitis?
A
- Failure to improve clinically
- Immunocompromised host
- S. pneumoniae resistant to penicillin/cephalosporins
- Meningitis due to gram neg bacilli
8
Q
What are the treatment regimens for the following manifestations of Lyme disease:
- Early localized
- Facial palsy
- Meningitis
- Heart block / carditis
- Arthritis
A
- Early localized - Docycycline 10d (or amoxicillin or cefuroxime 14d)
- Facial palsy - doxycycline 14d
- Meningitis - ceftriacone q24h then doxycycline 14d
- Heart block / carditis - doxycycline 14-21d
- Arthritis - doxycycline 28d
9
Q
What are the risk factors for invasive meningococcal disease?
A
- High risk for severe disease
- Asplenia, hyposplenia
- Complement (+factor D, properdin) deficiencies, including eculizimab therapy
- Primary antibody deficiency
- HIV
- High risk of exposure
- Travel (meningitis belt, Hajj)
- Lab worker, barracks living
10
Q
What are risk factors for HCV infection in children, infants and youth?
A
- Born to mother who is HCV-positive
- Born or lived in a region with high HCV prevalence (e.g. East Asian, Latin America, Middle East, Africa)
- Injection, intranasal or inhalational drug use with shared equipment
- Engaging in unprotected sex where blood may be present (e.g. condomless, anal intercourse)
- Being a victim of sexual assautl
- Exposure to non-sterile medical, dental or personal service equipment (e.g. unsafe tattooing)
- Receipt of invasive medical procedure in countries where infection prevention and control (IPC) practices are not standardized
11
Q
What are the recommended antimicrobials for pneumonia (uncomplicated and otherwise)?
A
-
Antimicrobial therapy
- Goal: good coverage for Strep pneumonia
- First choice for uncomplicated pneumonia: amoxicillin
- Course: 7-10 days (evidence that 5 days is likely sufficient)
- If hospitalization required but no life-threatening condition, switch to Ampicillin
- If respiratory failure or septic shock: third-generation cephalosporin (i.e. ceftriaxone)
- Better coverage for: betal-lactamase-producing H influenza & may be better for high-level penicillin-resistant pneumococcus
- If rapidly progressing multi lobar disease or pneumatoceles: add Vancomycin for MRSA coverage
-
Empyema: predominance of S pneumoniae, but can be due to GAS & S aureus
- Obtain pleural fluid culture (S aureus usually grows)
- If unwell, consider staph/MRSA coverage
12
Q
What is the indication for VZIG?
A
- Within 10 days of exposure
- Immunocompromised patients without evidence of immunity
- Newborn infants whose mothers have signs and symptoms of varicella around the time of delivery (i.e., 5 days before to 2 days after)
- Premature infants born at ≥28 weeks GA who were exposed to VZV and whose mothers do not have evidence of immunity
- Premature infants born at <28 weeks GA or who weigh ≤1,000 g at birth who were exposed to VZV, regardless of their mothers’ evidence of immunity
- Pregnant women without evidence of immunity if exposed to VZV
13
Q
How is botulism diagnosed and treated?
A
-
Diagnosis and evaluation
- Detection of toxin in stool
-
Treatment
- Infants: botulism IV immunoglobulin (BabyBIG)
- Children and adults: botulism antitoxin (BAT)
- Supportive care (which may include endotracheal intubation and mechanical ventilation for respiratory failure)
- Antibacterial therapy not recommended unless there is secondary infection
14
Q
What are the risk factors for MRSA?
A
- Risk factors:
- Close skin-to-skin contacts
- Openings in the skin, such as cuts or abrasions
- Contaminated items and surfaces
- Crowded living conditions
- Poor hygiene
- Affected groups:
- Indigenous populations
- Athletes
- Daycares
- Military recruits
- IV drug users
- MSM
- Prisoners
15
Q
How are soft tissue abscesses managed in children by age group?
A
16
Q
What are the benefits and limitations for using Septra in treating soft tissue infections / abscesses?
A
- NOTE: poor penetration for deeper infections (lungs, pus, thick-walled abscesses)
- INDICATION: still ok for uncomplicated abscesses
- ALTERNATIVE: clindamycin (but there are resistant strains, greater risk of C diff)
- Linezolid: good drug for CA-MRSA, but very expensive and not a 1st line
- LIMITATION: poor coverage for GAS
- Consider adding Keflex for significant cellulitis while awaiting cultures
17
Q
How many children with TB develope a primary infection? How many with latent TB develop reactivations?
A
5-10% for both!
18
Q
What population is particularly at risk for bad TB infection?
A
< 5 years old
19
Q
In which population is reactivation of latent TB mostly seen?
A
- Most commonly occurs in adults or youth (not children)
- Risk factors: immunosuppression (e.g. HIV, DM), malnutrition or medications (e.g. steroids)
- Pulmonary reactivation: often cavitary lesions (i.e. apical, upper lung zones)
- Other manifestations: CNS lesions, lymphadenitis, pleural effusions, hepatic/splenic abscesses, etc.
20
Q
What does an IGRA work and when is it indicated?
A
- IGRA: evaluates immune response by measuring inter-feron gamma by T cells in response to antigens specific for Mtb → no cross-reactivity with BCG and nontuberculosis mycobacteria (NTM) → spec > 95% (60% TST)
- More specific in >2yo (especially in past BCG), TST more sensitive in <2yo (so 1st line for <2yo)
21
Q
What is the suggested management for high risk TB contacts?
A
- Take a history, physical exam, CXR, perform initial TST
- If <5yo, TST <5mm —> give prophylaxis
- Repeat TST 8-10wk after last contact
- If >5yo & TST <5mm, repeat TST 8-10wk later. No prophylaxis
22
Q
What is the name of the syndrome when cat scratch disease leads to unilateral conjunctivitis and unilateral preauricular lymphadenopathy?
A
Parinaud oculoglandular syndrome
23
Q
What are the clinical features of cat scratch disease?
A
- Incubation period: 7-12 days
- 1+ 3-5mm red papules develop at site of inoculation (e.g. linear cat scratch)
- Seen in at least 65% when closely examined
-
Lymphadenopathy within 1-4 weeks, duration: 1-2mo
- Typically unilateral & tender, but no erythema
- Typical size: 1-5cm
- 10-40% eventually drain
- Fever in 30%
- Non-specific: malaise, anorexia, headache, fatigue
- Parinaud oculoglandular syndrome: unilateral conjunctivitis -> preauricular lymphadenopathy (in 2-17% of cases)
- Hepatosplenomegaly: may occur, high ALT -> indicates systemic disease
- Granulomatous osteolytic lesions: localized pain, no swelling or erythema
24
Q
What is the treatment of cat scratch disease?
A
- Antibiotics not clearly beneficial for most cases -> observation sufficient
- Small prospective study: azithro -> only benefit was decrease in size in 1st 30 days
- If treatment considered, good agents: azithro, clarithro, septra, rifampin
-
If suppurative LN tense & painful: drain with needle aspiration
- If non-suppurative: don’t drain, may result in chronic drainage
- Surgical excision rarely needed
- Hepatosplenic involvement: rifampin 20mg/kg x14d +/- septra
25
What is the bacteria implicated in improper preparation of powdered formula?
* Powder preparations are not sterile, though # of bacteria forming colony-forming units per gram are usually lower than the allowable limit
* Nevertheless, there have been outbreaks of **_Enterobacter sakazakii_**
* Now called **Cronobacter sakazakii**
* Found naturally in the environment & can live in dry foods
* Mostly affect prems, immunosuppressed kids also at risk
* Can cause sepsis and meningitis
26
What is the rate of transmission of HIV, Hep C, and Hep B in blood transfusions?
HIV: 1 in 21 million
HCV: 1 in 7.6 million
HBV: 1 in 7.5 million
27
What is the 2 step strategy to reduce vertical HIV transmission?
* **Identify women infected with HIV**
* HIV testing early in pregnancy should be standard of care for ALL women in Canada
* If high risk, repeat if initially seronegative (repeat before 36wk ideally)
* If no testing previously, do RAPID HIV testing at delivery of mother
* If acute maternal infection suspected, must do HIV PCR (could be seroneg)
* If unable to do maternal testing, newborn MUST undergo rapid testing
* If parents refuse -\> call CAS
* Confirmatory testing for infant must be done with HIV PCR
* **Ensure access to HIV care for mothers & infants**
* If mother + -\> consult specialist to manage HIV who will counsel on prevention of transmission to infant & sexual partners, appropriate antiretroviral therapy, optimal F/U during pregnancy, and intrapartum and postnatal prophylaxis
* If mother is + at or after delivery OR if infant is + -\> consult peds ID urgently for immediate initiation of antiretroviral therapy (\<72h post-delivery)
* If infant or mother +, defer breastfeeding until confirmatory testing is done
* Infants on antiretrovirals need monitoring:
* Short term: neutropenia, anemia, lactic acidosis
* Long term: general health, growth & neurodevelopment
* Long-term impacts of HIV therapy on develops is unknown
28
What are the risk factors for HIV transmission (vertical)?
* Late or no prenatal care
* IV drug use
* Recent illness suggestive of HIV seroconversion
* Regular unprotected sex w/ HIV+ partner
* Dx of STIs during pregnancy
* Emigration from HIV-endemic areas
* Recent incarceration
29
Which groups of people are at high risk of influenza-related complications or hospitalizations?
* Children 6mo-59mo (5yo)
* All people ≥ 6mo with chronic health conditions:
* Cardiac or pulmonary disorders, including bronchopulmonary dysplasia, cystic fibrosis, asthma
* DM and other metabolic diseases
* Cancer, other immune-compromising conditions (due to underlying disease, therapy, or both)
* Renal disease
* Anemia or hemoglobinopathy
* Neurological or neurodevelopmental conditions (includes seizure disorders, febrile sz, isolated DD) does not include migraines or neuropsych
* Morbid obesity (BMI \> 40)
* Prolonged tx with ASA → risk of Reye
* Indigenous peoples
* All residents of chronic care facilities
* All pregnant women, including teens, in all trimesters
* All adults ≥ 65yo
30
What are the contraindications to the flu vaccine (in general and for LAIV specifically)?
* All types:
* Anaphylaxis to previous dose of influenza vaccine or any component of vaccine (exception: eggs)
* Onset of Guillain-Barre Syndrome within 6 weeks of influenza vaccine without other known cause
* LAIV
* \<2yo
* Immunocompromising conditions
* Severe asthma (current active wheezing or currently on oral or high-dose inhaled GCs or medically attended wheezing in the previous 7 days)
* During pregnancy
* Children 2-17yo on ASA therapy (risk of Reye syndrome)
* Severe nasal congestion → defer until resolved or give IIV
* Close contact with severely immunocompromised (if LAIV given, avoid contact for 2wk)
31
What is the treatment for listeria?
* Ampicillin IV +/- aminoglycoside
* Role of aminoglycoside: enhances bactericidal activity -\> recommended in cases of meningitis or endocarditis
* NOT susceptible to 3rd generation cephalosporins
* Gastroenteritis: NO antibiotics needed unless invasive disease present
* Duration: 2-3wk for immunocompromised patients and meningitis
* Longer for endocarditis, brain abscess, osteomyelitis
32
What is the post-exposure prophylaxis recommendations for: Measles, Varicella, Hep A, Hep B, Meningococcus, Tetanus, and Diphtheria?
33
What are the most common presentations for invasive group A strep?
* Toxic shock syndrome (TSS) +/- focus of infection
* Necrotizing fasciitis or myositis with no septic focus
* Pneumonia
34
What is the antimicrobial therapy for severe invasive group A strep (TSS, Nec fasc, confirmed GAS)?
* TSS
* Empiric antimicrobial therapy: coverage of GAS and Staph aureus with a beta-lactamase stable beta-lactam (i.e. cloxacillin) in combination with clindamycin (for synergy)
* Add Vancomycin in areas with significant rates of MRSA colonization
* Nec Fasc
* Empiric: beta-lactam-beta-lactamase inhibitor (e.g. Pip-Tazo) or a carbapenem, in combination with clindamycin +/- Vancomycin (MRSA coverage, deepening on local prevalence and RFs)
* Confirmed GAS
* Penicillin is drug of choice
* Adding clindamycin (strongly recommended): potent inhibitor of toxin production with antimicrobial activity
* Can discontinue Clindamycin after 48-72h once hemodynamically stable, blood is sterile and no further progression of necrosis
35
What is the cut-off for meningitis susceptibility breakpoints?
* Penicillin susceptible if MIC ≤ 0.06mcg/mL
* Penicillin resistant if MIC ≥ 0.12 mcg/mL
36
What is the recommendation for duration of antimicrobials in meningitis by pathogen?
* Typical duration: depends on clinical course
* Strep pneumoniae: 10-14 days
* Hib: 7 - 10 days
* N meningitidis: 5-7 days
37
What is the impact of giving Hep B vaccine and immunoglobulin to prevent vertical transmission? How about maternal anti-virals?
* Infants born to mother HBsAg+ have 10-90% risk of developing Hep B infection
* Of those infected, 90-95% develop chronic infection
* Prevention: Hep B immune globulin + Hep B vaccine -\> reduces risk to 2-4%
* Maternal anti-virals: reduces risk by 68%
38
What are signs that distinguish Zika virus from other congenital infections?
* Severe microcephaly with partially collapsed skull
* This cerebral cortices with subcortical calcifications
* Macular scarring and focal pigmentary retinal mottling
* Congenital contractures
* Marked early hypertonia and symptoms of extrapyramidal involvement.
* *No consistent reports of abnormalities outside the CNS.*
39
What are the 5 recommended steps for HCPs to work with vaccine hesitant families?
1. Understand the key role that sound vaccine advice from a HCP ca play in parental decision-making, and do not dismiss vaccine refusers from your practice
2. Use presumptive and motivational interviewing techniques to understand parent’s specific vaccine concerns
3. Use simple, clear language to present evidence of disease risks and vaccine benefits, fairly and accurately
4. Address pain head on
5. Community protection (herd immunity) does not guarantee personal protection
40
What are the 8 components of the vaccine safety system?
1. Evidence-based pre-license review and approval process
2. Regulations for manufacturers
1. Good lab practices (GLPs), good clinical practices (GCPs), good manufacturing practices (GMPs), vaccine lot assessment, regular review of vaccine safety data submitted by the market authorization holder
3. Evidence-based vaccine use recommendations
4. Immunization competencies training for HCPs
5. Pharmacovigilance for adverse events following immunization (AEFIs)
1. AEFI post-marketing surveillance
2. AEFI monitoring (CAEFISS): passive, enhanced and active (IMPACT)
3. Global surveillance (Uppsala Monitoring Centre)
6. AEFI causality assessment
7. Safety and efficacy signal detection
8. Canadian immunization research network special immunization clinics (SICs)
41
What are the indications for the quadrivalent conjugated meningococcal vaccine?
- Adolescent booster (except Manitoba, Quebec, Nunavut)
- 2-3 doses starting at 2mo for kids at risk due to medical conditions → Booster at 12-13mo, Q3-5y until 7y, then Q5y
- Individuals ≥2 months of age traveling to countries with a high risk of invasive meningococcal disease or those with a high risk of exposure (2-3 doses if \<12mo, 2 if 1-2y, 1 if \>2y)
- Men-C-ACYW-CRM (Menveo®) is currently recommended over the other two available brands (Men-C-ACYW-DT, (Menactra®) and Men-ACYW-TT (Nimenrix®)) for children \<2 years of age
42
What are conditions making patients at high risk for invasive meningococcal disease (i.e. should receive quadrivalent vaccine)?
* Risk increased because of _underlying medical conditions_
* Asplenia or functional asplenia, including those with sickle cell anemia
* Properdin, factor D or complement deficiency (including those with acquired complement deficiency from eculizumab (Soliris); primary antibody deficiency
* HIV
43
What are populations at increased risk for invasive meningococcal disease due to POTENTIAL EXPOSURE?
* Laboratory workers who work with meningococcus
* 1 dose of Men-C-ACYW and 4CMen B OR MenB-HBP + booster Q5y
* Military personnel living in close quarters
* 1 dose of Men-C-ACYW and 4CMen B OR MenB-HBP + booster Q5y
* Travelers to endemic areas (currently, travelers to sub-Saharan Africa and *Hajj* pilgrims)
* Individuals ≥2 months of age traveling to countries with a high risk of invasive meningococcal disease or those with a high risk of exposure (2-3 doses if \<12mo, 2 if 1-2y, 1 if \>2y)
* Close contacts of a case of IMD
* Immunization +/- booster (discuss with Medical Officer of Health)
44
What is the CENTOR score for GAS?
* CENTOR Clinical decision for children 3-14
* Exudate or swollen tonsils
* Tender anterior cervical LNs
* Fever
* No cough
* If score is 3 or higher, do a throat swab. 30-50% of probability of GAS infection. Don’t do swab if sx of viral URI because they could just be carriers
* ASO is not helpful because it cannot distinguish from carrier to infection
45
What is the management for seemingly recurrent GAS infections?
* Children with recurrent sore throat and have positive throat cultures for GAS or recurrent GAS infection
* Likely chronic carriers
* Check adherence to treatment and response to therapy
* If suspecting that it is being passed back and forth, may be worthwhile to test child in asymptomatic interval to see if they’re really clearing the infection
* If treating for eradication - 10 day course of Clavulin, Clinda
46
How is community-acquired MRSA (emerging in indigenous populations) different from health care acquired MRSA?
* CA-MRSA generally more susceptible to antimicrobials (exception of beta-lactam derived drugs)
* Mostly cause skin and soft tissue infection
* Cause significant morbidity and mortality when invasive infections occur
* CA-MRSA: specific virulence factors that produce cytotoxin capable of tissue necrosis
* Most common CA-MRSA strains: CMRSA10 and CMRSA7
47
What are reasons to contact public health for MRSA infections in indigenous populations?
Consult public health about a recurrent infection **(three or more** infections in the same individual within a **six-month period**) or **if an outbreak in a closed population,** such as a day care or athletic team, is suspected.
48
What is scabies and how is it transmitted?
* Mite: Sarcoptes scabiei → transmitted direct skin-to-skin
* Can only live on skin for 24-36h, only limited transmission through fomites, such as clothing and bed linen
* Female adult mite burrows in epidermis → deposits eggs over several days → larvae hatch 2-4d later → take about 10-14 days to mature into adult mites (avg infection 10-15 adult female mites)
* Infection is due to hypersensitive reaction to mite, its eggs and feces, about 3wk post-1st exposure
* If repeat exposure → can be faster due to more rapid immune response
49
What are the clinical features of scabies?
* Burrows → located between fingers, flexure of wrist, elbows or armpits, genitals or breasts
* Infants and elderly: burrows may be on the H&N → may look like vesicles, pustules or nodules
* Erythematous papule
* General pruritus → worse at night
* Superimposed bacterial infections (impetigo, pyoderma) due to Staph aureus or GAS → risk of PSGN, rheumatic fever
* Stigmatization, depression, insomnia, financial costs
50
What is crusted scabies ('Norwegian scabies')?
* Rare condition caused by host response to control the mite → hyper infestation with millions of mites, severe inflammation and hyperkeratotic reaction
* ½ have no itching
* More common in immunodeficient hosts (e.g. HIV, HTLV1, leukemia, lymphoma, autoimmune disease)
* Commonly misdiagnosed as psoriasis
* More contagious →higher risk of outbreak
* More difficult to treat than classic scabies
51
What are the possible indications for ivermectin use in scabies?
Outbreaks (only one PO dose = convenient) or crusted scabies
52
What are the recommended scabies control measures?
* Treat all symptomatic and asymptomatic household members and close contacts
* To prevent reinfection, treat all household members and close contacts at the same time as the known case
* All bed linen (sheets, pillowcases, blankets) and clothing worn next to the skin (underwear, T-shirts, socks, pants) should be laundered using a hot cycle wash and hot drying cycle
* If hot water is not available, put all linen and clothing into sealed plastic bags and store them away from household members and close contacts for **5-7 days** → mites cannot survive beyond 4 days without skin contact
* Children may return to child care or school **the day after** completing their initial treatment series
* By improving living conditions and building local expertise in Indigenous communities, individuals morbidity and the risk of scabies spread can be reduced
