CPS Infectious/Immunization 2 Flashcards
What are the 3 stages of lyme disease?
- Early localized disease: erythema migrans (painless and non-pruritic), may have fever, malaise, headache, myalgia and arthralgia
- Early disseminated disease: recurrence of erythema migrans distributed throughout body (cutaneous dissemination of spirochetemia), lyme carditis, facial nerve palsy, aseptic meningitis
- Late disease: large joint arthritis (usually knees)
Why is 2 step testing required for lyme disease diagnosis?
-causes for false positives?
ELISA first, then western blot
-western blot is necessary to confirm diagnosis since ELISA can be falsely positive from other spirochetes, viral infections or autoimmune diseases
What is the Jarisch-Herxheimer reaction?
Fever, headache, myalgia and aggravated clinical picture lasting < 24 hrs when treatment for lyme disease is initiated
-treat with NSAIDs and continue lyme treatment
A child who has completed the full course of Lyme disease antibiotic treatment returns within 3 months with chronic complaints of fatigue, joint and muscle aches. What is your diagnosis?
Post-treatment lyme disease syndrome
- exact cause unknown
- 10-20% of cases
- lingering symptoms may be result of residual damage to tissues and immune system
- this is NOT evidence of persistent infection
- no treatment available (more abx will not help)
What is the recommendation for post-exopsure prophylaxis for lyme disease?
-when is it indicated?
There is no consensus on whether we should do it
- some experts recommend for children > 8 yo after a tick bite in a known endemic area: doxycycline PO x 1 dose within 72 hrs of removing a tick
- insufficient data to suggest amoxil prophylaxis for young children
A mother comes to you with mastitis and a breast abscess. She asks if she should continue breastfeeding. What do you recommend?
Continue breastfeeding UNLESS there is obvious pus! If there is, then pump milk and discard from the infected breast and continue to breastfeed from the other breast
A mother comes to you with a new diagnosis of TB. She asks if she should continue breastfeeding. What do you recommend?
Main route of transmission is airborne, NOT via breastmilk BUT tell mom to delay breastfeeding until she has received 2 wks of appropriate anti-TB therapy.
- should also provide TB prophylaxis for infant
- infant can be fed EBM during the 2 weeks of no breastfeeding
What are the only maternal infections that are a contraindication to breastfeeding? (5)
- HIV
- Human T cell lymphotrophic virus (HTLV)
- TB (until mom has completed 2 wk course of anti TB meds)
- Untreated Brucellosis (infection may be passed through breast milk)
- HSV lesions directly on the breast (until lesions are crusted over) - can still use EBM
Can mothers with Hep A, B or C breastfeed?
Yes!
- For Hep A, give baby Hep A immunoglobulin for prophylaxis.
- For Hep B, give baby infant HBV immunoglobulin at birth and immunization with HBV vaccine
What is a contraindication to primiquine treatment for malaria?
G6PD deficiency
Which is the only antibiotic where you should discontinue breastfeeding x 12-24 hrs to allow excretion of dose after taking each dose?
High-dose metronidazole
What are nits?
Eggshells where baby lice (nymphs) are born from
What is an infestation with lice called?
- how are head lice transmitted?
- how do you make a definitive diagnosis of head lice?
Pediculosis
- direct hair-to-hair contact
- controversial whether fomites can transmit lice
- definitive diagnosis requires detection of a living louse (presence of nits may indicate that a past infestation occured but may not be currently active if you cannot find a louse)
What are the different treatment options for head lice infestations?
- **Need 2 treatments 1 wk apart
- minimize body exposure, do not let the child sit in the bath water as the hair is being rinsed!
- Pyrethrins shampoo
- caution in people who have ragweed allergy as may cause allergic reaction
- safe - Permethrin rinse
- safe - Lindane shampoo (2nd line)
- neurotoxicity to both lice and humans
- concerns with bone marrow suppression with skin absorption
- do NOT use in young children, infants, pregnant/nursing mothers or people with history of seizures - Noninsecticide = Resultz (myristate/cyclomethicone)
- dissolves waxy exoskeleton of louse leading to dehydration and death
- do not use for children < 4 yo - Ivermectin PO = anti helminth
- 2 single doses 10 days apart, may be neurotoxic, used for children who cannot use topical shampoos, very special circumstances only
You have treated a child for head lice but they come back within a week with continued infestation. What is your differential diagnosis for treatment failure? (3)
- Wrong diagnosis? Make sure you look again for a living LOUSE before you say this is treatment failure (not just presence of nits)
- Poor compliance with instructions for proper application of topical insecticide or lack of secondary application or reapplication too soon after 1st
- New infestation acquired after treatment
You have treated a child for head lice but they come back within a week with continued scalp itching. What do you tell them?
Itching post-topical insecticide is common and does NOT mean that a reinfestation has occurred! Topical insecticide can cause rash/itching. Topical steroids/antihistamines may help.
Is wet combing useful either alone or in combination with a topical insecticide for curing head lice infestations?
No! Shown in multiple trials to not be useful
You have diagnosed a child with head lice infestation. Mom asks if he should be kept home from school until he is lice-free. What do you say?
-mom also asks you if she should disinfect all his personal items. What do you say?
No! He can still go to school as long as there is no head-to-head contact!
- no clear data on whether disinfection of fomites leads to decreased chance of reinfestation.
- Head lice cannot survive far away from scalp and nits are unlikely to hatch at room temperature.
- so overall, just clean things with intimate contact with the head like hats, brushes/combs, pillowcases –> dry in hot dryer x 15 mins, place in occlusive plastic bag x 2 wks, or wash in hot water
What is the risk of vertical transmission with:
- untreated primary or secondary syphilis
- early latent syphilis
- late latent syphilis
- Untreated primary or secondary syphilis: 70-100%
- early latent syphilis: 40%
- late latent syphilis: 10%
A baby is born but mom has never been tested for syphilis. Baby is completely well and mom wants to go home. What is your management?
If syphilis serology was not performed during pregnancy, do not discharge the newborn home until maternal serology has been drawn and follow-up of results has been arranged
What is the infectious etiology of syphilis?
Treponema pallidum
What are causes of false-positive tests for syphilis? (2)
- Autoimmune conditions
2. Lyme disease
What is the screening approach used in Canada for syphilis?
- which of the tests will remain positive for life despite treatment?
- which of the tests is used to monitor effectiveness of treatment?
Use nontreponemal tests (RPR ie rapid plasma reagin) or VDRL ie. venereal disease research lab test) as initial screen, then confirm a reactive result with a treponemal test (fluorescent treponemal antibody absorption test = FTA-ABs)
- treponemal tests remain positive for life (ie. FTA-ABs)
- RPR titres is used to stage infection and to monitor the response to treatment (may revert to nonreactive after treatment)
A pregnant woman comes to you with a reactive treponemal test and a nonreactive RPR during pregnancy with no history of treatment and no evidence of early primary syphilis. What do you do?
This is a sign of late latent syphilis and thus there is risk of vertical transmission thus you TREAT for late latent syphilis: Benzathine Pen G x 3 doses on weekly basis
A pregnant woman comes to you with a reactive RGR and negative treponemal tests (FTA-ABS & TP-PA). What is your diagnosis?
False positive! It is not possible for your RPR to be positive while treponemal tests are negative in true syphilis!
What is the most common way that congenital syphilis is diagnosed?
Diagnosis relies on positive lab and/or radiographic findings since MOST infants with early congenital syphilis (syphilis diagnosed in 1st 2 years of life) are asymptomatic at birth
Aside from laboratory testing, how else can you diagnose congenital syphilis?
You can examine any skin lesions, nasal discharge, placental lesions or umbilical cord for treponemes with darkfield microscopy or FTA-ABS
What is necrotizing funisitis?
Umbilical cord that looks like a barbershop pole: pathognomonic finding for congenital syphilis
What are the clinical features of congenital syphilis? (9)
- Spontaneous abortion/stillbirth/hydrops fetalis: 40% of cases if acquired during pregnancy
- Necrotizing funisitis
- Rhinitis/snufles
- Diffuse maculopapular rash including palms/soles
- HSM
- Lymphadenopathy
- Neurosyphilis
- Osteochondritis/perichondritis seen radiographically
- Anemia/thrombocytopenia
What are late clinical features of congenital syphilis? (4)
- Interstitial keratitis
- Hutchinson teeth
- Mulberry molars
- 8th CN deafness
A pregnant woman with a well-documented history of adequate treatment of syphilis BEFORE pregnancy who had no rise in her RPR titre during the pregnancy and no other risk factors for infection delivers her baby. What is your management of the baby?
No need for further testing or treatment.
A pregnant woman was treated for primary/secondary/early latent syphilis during pregnancy > 4 wks prior to delivery with an adequate fall in RPR titres. There is no evidence of relapse or reinfection. She delivers her baby. What is your management of baby?
- Baseline and MONTHLY assessment of baby for s/s for congenital syphilis x 3 mo
- Syphilis serological tests: RPR, treponemal tests at 0, 3, 6, 18 mo
-lower risk of acquisition so no empiric treatment
What is your management plan if a baby is born to a mother with untreated primary or secondary syphilis and baby is found to have rising RPR titre, clinical findings of congenital syphilis, and positive treponemal test?
- RPR & treponemal tests at 0, 3, 6, 18 mo
- Long bone radiographs (to assess for osteochondritis/perichondritis)
- Bloodwork: CBC + diff (to look for anemia/thrombocytopenia)
- CSF sampling for cell count/biochem/VDRL (poor sensitivity but excellent specificity) to r/o neurosyphilis
- Ophtho & Audio assesment
- Treatment for congenital syphilis: Pen G IV x 10-14 d
***You repeat serology often because Pen G does not cure every case of congenital syphilis
Why are children more prone to getting AOM than adults? (4)
- Eustachian tubes are shorter and more horizontal
- Eustachian tubes are more prone to obstruction by enlarged adenoids
- Viral infections/allergies more common in young children leading to eustachian tube inflammation
- Children have decreased levels of IgA and thus get more bacterial adherence in the nasopharynx
What is the pathophysiology behind the development of AOM?
Obstruction of eustachian tube (usually caused by viral infection causing eustachian tube inflammation) –> mucociliary clearance impairment –> mucus trapping in middle ear space –> resoprtion of gases within the middle ear space creates a pressure differential (vaccuum) and sucks bacteria from the nasopharynx into the middle ear space –> bacteria grow and cause infection
What are the risk factors for development of AOM? (12)
- Young age
- Daycare attendance
- Craniofacial abnormalities (cleft palate)
- Down syndrome
- Household crowding
- Exposure to cigarette smoke
- Premature birth
- Bottlefeeding
- Immunodeficiency
- Family history of AOM
- First nations/Inuit
- Pacifier use (related to frequency of use)
What are clinical features of AOM? (3 main categories)
- Signs of middle ear effusion:
- immobile TM or acute otorrhea (ruptured TM)
- dull TM
- loss of bony landmarks behind TM
- visible air fluid level behind TM - Signs of middle ear inflammation:
- bulging TM with marked discoloration - Acute onset of symptoms:
- rapid onset of ear pain or unexplained irritability in a preverbal child
What is the most common cause of AOM?
Non typable H influenza
-used to be strep pneumo but now that we have the conjugated pneumococcal vaccine, strep pneumo is less common
When is the watchful waiting approach appropriate in antibiotic treatment of AOM?
If child is > 6 mo, healthy (ie. no immunodeficiency, chronic health issues, history of complicated otitis media) with MILD signs and symptoms and parents are capable of recognizing worsening and can access medical care quickly
-ie. mild otalgia, fever < 39 degrees celcius
What are 3 complications of untreated AOM?
- Mastoiditis
- Meningitis
- Intracranial abscess
AOM caused by which organism is the least likely to spontaneously resolve?
Strep pneumo (20% spontaneous resolution compared with 50% seen with H flu)
What are the risk factors for AOM with antimicrobial resistant S. pneumo? (4)
- Daycare attendance (more likely to be colonized due to increased contact with other children
- < 2 yo
- History of frequent OM and/or recent abx use within past 3 months
- Failed initial antimicrobial therapy for AOM
Which oral drug is most likely to be effective against penicillin-resistant S. pneumo AOM?
Amoxicillin!!! Even though it is a penicillin, if given in a high dose, it has excellent middle ear penetration and thus reaches a high enough concentration to overcome most resistant strep pneumo species
What is the 2nd line therapy for AOM if a child has a type 1 hypersensitivity (urticaria or anaphylaxis) reaction to amoxicillin?
-what if the previous reaction to amoxicillin was not type 1?
Macrolide: clarithromycin or azithromycin
-if not type 1 reaction, then can use 2nd generation cephalosporin (cefprozil, cefuroxime axetil)
A child with AOM has a type 1 hypersensitivity reaction to Amoxicillin and has failed macrolide therapy. What is your management?
- Consider clindamycin or quinolone in consultation with ID specialist.
- Consider ENT referral for tympanocentesis to determine organism and to guide therapy
A patient who you’ve treated for AOM comes back to your office after 2 days of being on amoxicillin with no improvement in symptoms. What is your management?
Symptoms should’ve improved within 1-2 days of starting abx and resolve within 2-3 d of starting abx.
- change the abx to target highly pen-resistant strep pneumo and beta-lactamase producing organisms
- change the abx to Amoxi-clav
- if this does not work, then Ceftriaxone IM/IV OD x 3 days
A 5 yo patient who was recently treated at a walk in clinic for AOM with a complete course of abx comes to you for a routine check up. On exam, you see a persisting middle ear effusion. He is otherwise completely asymptomatic now. What is your management?
DO NOTHING!
-middle ear effusions can last for months after AOM despite clinical and bacteriological resolution
What is the dose and duration of treatment of amoxi-clav for AOM?
Amoxil 90 mg/kg/day + Clavulanate 6.4 mg/kg/day div BID x 10 d
What is the first line treatment for AOM?
-dose?
Amoxil 90 mg/kg/day div BID
What is the appropriate duration of abx therapy for AOM?
Children > 2 yo: 5 days
-children < 2 yo, recurrent AOM or perf TM, failure of initial abx: 10 d
Which children warrant a 10 d course of abx for AOM? (4)
- < 2 yo
- Frequent AOM
- Perf TM
- Failed 1st abx course
You have just diagnosed a patient with AOM. His mother asks you what she could do to prevent future AOM. What do you say? (4)
-2 best vaccines to prevent AOM?
- Hand hygiene!
- Exclusive breastfeeding until at least 3 months of age
- due to absence of bottle feeding which is a RF and also to maternal immunoglobulin transfer - No smoking!
- Limit use of pacifier
- two best vaccines: influenza vaccine and pneumococcal conjugate
Why does bottle feeding lead to increased risk of AOM?
Especially if bottle is propped, baby has to suck hard and excessively to get milk –> this generates negative pressure inside within the eustachian tube thus pulling bacteria from the nasopharynx in
What is the most common diarrheal illness associated with hospitalization?
-which age group has the highest risk of severe disease?
Rotavirus
-highest risk of severe disease = children < 2 yo (more likely to have a “sepsis-like” clinical picture at presentation compared with older children)
How long do rotavirus infections last for?
-most commonly seen symptoms? (3)
3-8 days
- Vomiting
- Diarrhea
- Fever
What are risk factors for severe rotavirus disease? (3)
- Premature babies (lack transplacental maternal abs)
- Immunocompromised
- Children < 2 yo
What are the two rotavirus vaccines available in Canada?
- similar characteristics
- distinguishing features
Both given orally at minimum of 6 wks with maximum age for dose 1 of 14 wks + 6 d of age, doses given 1 month apart
- RotaTeq
- 3 doses required
- covers G1-G4P & P1
- live, pentavalent vaccine - Rotarix
- 2 doses required
- covers G1P
- live-attenuated monovalent (G1 is the most common circulating strain worldwide and other circulating strains are rare)
What are possible adverse effects of RotaTeq vaccine? (5)
- Vomiting
- Diarrhea
- Nasopharyngitis
- Otitis media
- Bronchospasm
***These are small but statistically significant
What are contraindications to rotavirus vaccines? (3)
- Hypersensitivity to the vaccine or ingredients
- Immunocompromised
- History of intussusception (based only on previous association with RotaShield with pathogenesis still unclear)
* **These is no association between the new vaccines and intussusception
What is the recommended age group for rotavirus vaccine?
-who should receive rotavirus vaccine?
Vaccination should be started between 6-14 wks+6 days of age and be FINISHED by 8 months of age (safety of vaccine outside of these recommendations is unknown)
- recommended for ALL infants because it significantly decreases the incidence and morbidity associated with rotavirus infection
- may not prevent all cases of rotavirus diarrhea but do prevent severe disease and decreases risk of dehydration and hospitalization
Define the following:
- Sterilants
- Disinfectants
- Sanitizers
- Fungicides
- Sterilants: will kill all forms of microbial life
- Disinfectants: kill infectious pathogenic bacteria
- Sanitizers: reduce the amount of microbial contamination
- Fungicides: destroy fungi on inanimate surfaces that are pathogenic
What are the antimicrobical mechanisms of action of the following:
- Alcohol
- Chlorhexidine
- Triclosan
- Quaternary ammonium compounds
- Alcohol: denature proteins
- Chlorhexidine: Disrupts cytoplasmic membrane
- Triclosan: disrupts cytoplasmic membranes, inhibits synthesis of RNA/fatty acids/proteins
- Quaternary ammonium compounds: disrupt cytoplasmic membrane
What is the recommended cleaning agent for spillage of body fluids?
Diluted bleach
What is the most common mechanism of resistance to antibiotics that bacteria exhibit?
-which cleaning agent has been shown to upregulate this mechanism?
Multidrug efflux pumps!
- concerning since this can result in cross-resistance to other antibiotics that the bacteria were not initially exposed to since multidrug efflux pumps are nonspecific in what they pump out of the cell
- pineoil has been shown to upregulate the efflux pumps, leading to resistance to several antibiotics
Is there definitive evidence that the use of biocides in cleaning products has contributed to the development of antibiotic resistance?
No….but there are relationships between antibiotic resistance and biocides that are mediated by a target gene mutation or increased expression of multidrug efflux pumps! Needs more research.
What is the procedure for cleaning up a body fluid spill at home?
- Wipe up the spill with paper towels and place in a plastic garbage bag.
- Make a solution of 9 parts water and 1 part bleach and pour onto contaminated surface
- Wait 20 minutes.
- Wipe up the bleach solution
- Disinfect all nondisposable cleaning materials used (ie. mops/brushes) by saturating them with bleach solution and allow to air dry
- Throw out everything else in the plastic garbage bag.
- Wash your hands!
Which of the following is false:
a. the CPS recommends the use of antimicrobial-impregnated household products
b. The CPS promotes hand hygiene using plain soap and water in the vast majority of domestic settings
c. Antimicrobial chemical agents may be used selectively in the home ni specific high-risk scenarios (ie. immunocompromised, neonate, old person)
d. Where appropriate, alcohol, bleach or peroxidase based agents are preferred sicne they dissipate readily and are less likely to exert prolonged antimicrobial pressure
A! They do NOT recommend this! Use of antiseptics and antimicrobials is unnecessary!
What is the mechanism of action of biologic response modifiers?
- examples of a biologic response modifier?
- schedule of administration?
Block the action of cytokines involved in inflammation in order to decrease inflammation
- ie. TNF-alpha inhibitors (infliximab ie remicade, adalimumab ie. humira), interleukin inhibitors (Abatacept)
- administered IV or subcutaneously weekly, q2wk, monthly or bimonthly depending on the disease being treated
What type of immunity is supprsesed by biologic response modifiers?
Cellular immunity - decrease ability of T cells to destroy cells with intracellular pathogens, decreased ability for granuloma formation
One of your patients is on a biologic response modifier for treatment of their JIA. What 3 types of infections are they at increased risk of acquiring?
- Mycobacteria: TB and non-TB
- Fungal
- Intracellular bacteria (listeria)
- no evidence regarding increased risk of common bacterial infections
- some evidence of viral reactivation with HSV/EBV, etc.
What is the work-up/counselling for a patient before initiation of biologic response modifier therapy? (7)
(Rule out latent TB):
- TST
- CXR
(Investigate for latent viruses):
- Document vaccination status and verify all are up to date, including yearly influenza vaccine. Administer live virus vaccines a minimum of 4 weeks before initiation of BRM unless contraindicated
- Serology for Hep B, VZV, EBV
(Rule out intracellular pathogens):
5. Serology for histoplasma, toxoplasma, other intracellular pathogens
(Counsel):
- Counsel household members for vaccination
- Counsel patient re: food safety, dental hygiene, avoid exposure to garden soil/pets/other animals, travel to endemic areas for pathogenic fungi or TB
A patient of yours with IBD needs to be started on remicade. You perform a TST as routine workup prior to starting remicade and the induration is found to be 8 mm. CXR is normal. What is your management?
- Diagnose patient with latent TB infection
- Treat for LTBI with isoniazid x 9 months.
- After patient has been on isoniazid x 1 month, can start treatment with remicade.
You are starting a patient on a biologic response modifier for their IBD. They ask you how to decrease risk of infection while immunosuppressed. What counselling do you provide re:
- food safety?
- contact safety?
- which organism are you avoiding with each of your recommendations?
- Food safety (decrease risk of infection with listeria, toxoplasma, etc.)
- avoid undercooked meat/eggs/deli meats
- avoid raw eggs or unpasteurized milk products (soft cheese) - Contact safety:
- avoid soil or kitty litter (for toxoplasmosis)
- avoid kittens (bartonella)
- avoid pet reptiles (for salmonella)
- avoid pet bites or scratches (pasteurella)
- avoid construction sites, farmyard barns, cave exploration (high concentration of fungal spores)
A patient received an MMR vaccination today but you also want to test them with a TST for TB. When is the earliest you can administer the TST to avoid a false negative?
4-6 wks after MMR immunization