Infectious Disorders (Raf with Danielle additions) Flashcards
What is the most common type of pulmonary infection in HIV?
- Bacterial pneumonia
- TB
Echinococcus genus (hydatid organism)–>how is it passed on? What is the treatment?
- Passed to humans by contact with eggs in feces of definitive host (eg. fox, wolf) or close contact with canine or sheep
- Treatment: surgical resection, or percutaneous drainage with treatment with albendazole, which also potentially used after treatment. For Canadian variety, may ok to just use medical treatment and not surgical
Post exposure prophylaxis for varicella?
Red Book algorithm
Immune or not?
Any contraindications to vaccine, which is ideally within 5 days?
If can’t get vaccine, are they within 10 day time frame for VZIG?
What does and duration of prednisone is defined as immunosuppression?
> =2 mg/kg/day x 14 days
What is the evidence for high flow in bronchiolitis?
CPS statement re: evidence in general:
- Extensive neonatal literature that there is decreased need for intubation and ventilation. (They don’t go into details about specific disease conditions)
- Pediatric studies have suggested reduced need for intubation, but studies were inadequately powered to show difference in mortality or length of icu stay. (They don’t specify these pediatric conditions)
Bronchiolitis:
NEJM 2018:
- Largest RCT to date
- Infants <12 months of age requiring oxygen for bronchiolitis were randomized to either receive low flow oxygen therapy or high flow at 2 L/kg/min
- Primary outcome: therapy escalation
- Secondary outcome: various including transfer to ICU, mortality, length of stay, intubation
- Finding: children on high flow were less likely to have an escalation in therapy compared to children on low flow, but there were no differences in any of the secondary outcomes, such as transfer to ICU
- Key critiques:
- The jump from high flow to further escalation is perceived as a bigger jump than from low flow to high flow, so this could explain the differencethey try and account for the difference in RR before escalation of therapy by doing a sensitivity analysis
- The presence of an ICU on site also affected decision for escalation of therapybut they also try and account for this with sensitivity analysis
Radiographic signs for Echinococcus
1) Meniscus sign/crescent sign
2) Cumbo sign/onion peel (double air layer appearance/onion peel/double arch)
3) Water lily
4) serpent sign
5) cavity
6) well defined round opacity (due to uncomplicated cyst, no rupture)
4) U/S: same as CXR + honeycomb appearance, ball of wool sign, cyst wall calcification
3 major forms for Echinococcus
Cystic (predominant form affecting lungs)
Alveolar
Polycystic
(two major organs affected are liver and lung. In children, lung is more commonly affected)
Treatment for Echinococcus
U/S guided aspiration of cysts
Surgery
Drugs: Albendazole or Mebendazole
Mechanisms of Acute Flaccid Paralysis causing lung disease
Atelectasis
Aspiration
Hypoventilation/respiratory muscle weakness
Secondary infection
Guillam Barre = autonomic neuropathy - cardiac failure - pulmonary edema
Causes of Acute Flaccid Paralysis
Enterovirus: polio and non-polio enteroviruses, D68 (anterior horn cell) West Nile (anterior horn cell) Guillain Barre (axon demyelination) Adenovirus (anterior horn cell) Botulism (NM junction) Tetanus (NM junction) Spinal cord compression
What are features of an airborne isolation room?
- negative pressure ventilation
- door closed at all times
- no opening of windows
- bathroom and hygeine area for patient
- handwashing sink for healthcare staff
- exhaust of air goes to outside of the building
- air has to go through HEPA filter before going to general circulation
- healthcare workers must wear N95 and be fit tested
Infectious disorders that cause GBS?
Often prior infection, resulting in molecular mimicry:
- Campylobacter jejuni - most important
- Mycoplasma pneumonia
Viruses- CMV, EBV, HIV, Influenza
- post vaccination, such as influenza
What organisms is a patient with CGD at risk of?
recurrent infections with catalase positive bacteria or fungi
The mnemonic “cats Need PLACESS to Belch their Hairballs” can be used to memorise the catalase-positive bacteria (and Candida and Aspergillus, which are fungi): nocardia, pseudomonas, PJP, listeria, aspergillus, candida, E. coli, staphylococcus, serratia, B. cepacia and H. pylori.[52] (so some common CF bugs like Pseudomonas and Burkholderia can actually be seen in CGD patients)
Where are endemic fungi located in Canada?
BC: cryptococcus
Manitoba: blastomycoses
Ontario: blasto and histo
Quebec: blasto and histo
What sorts of infections are patient with neutropenia at risk for?
Neutropenia:
- Decreased number of neutrophils: chemotherapy induced neutropenia
- Decreased function of neutrophils: CGD, steroids
- At risk for infection with bacteria and fungi
- Chemotherapy induced neutropenia: risk of infection with own bacteria such Strep, Staph. G - like E. coli, Klebsiella, Pseudomonas and Fungi like aspergillus
- CGD: see above
What infections are patients with impaired humoral immunity at risk of?
- Mostly bacteria, in particular encapsulated (Strep pneumo, Neisseria, Haemophilus, GBS, salmonella) and some virus (like enterovirus)
What infections are patients with cell mediated immunity problems at risk of?
Intracellular pathogens:
Viruses: CMV, VZV, EBV, community viruses (eg. RSV)
Fungi: PJP, aspergillus, endemic fungi
Intracellular bacteria like nocardia
Mycobacteria
Parasites: toxoplasma gondii and strongyloides
Conditions needing airborne precautions?
Active pulmonary TB (specify that it is active and pulmonary) VZV Measles SARS - severe acute respriatory syndrome small pox
Why is diphtheria deadly?
- Airway obstruction: diphtheria makes a toxin which destroys tissue and causes membranous pharyngitis–>these membranes can extend to larynx and can cause airway obstruction OR pharyngeal membrane can get dislodged and obstruct airway
- toxin also causes:
- myocarditis/cardiomyopathy
- sepsis
- secondary pneumonia
If suspicious of diptheria, do you wait for laboratory confirmation before giving anti-toxin?
No.
Diphtheria antitoxin to neutralize circulating toxin (administer before lab confirmation).
· Antibiotics (penicillin, erythromycin x 14d) to eradicate the organism, stop toxin production and reduce transmission, but do not replace antitoxin.
Most common cause of croup (D)
Parainfluenza
Infectious causes of upper airway obstruction (D)
Viral croup Epiglottitis Bacterial Tracheitis Diphtheria Retropharyngeal abscess Peritonisllar abscess Infectious mono
Non-infectious causes of upper airway obstruction (D)
FB Trauma Caustic burns Spasmodic Croup Angioneurotic Edema
Common causes of Epiglottitis (D)
Historically - H. influenzae (type B)
Now: Strep (Group A, B, C, G), H. parainfluenzae, Staph aureus, Moraxella catarrhalis,
Pneumococcus, Klebsiella, Psuedomonas, Candida, viruses