Infectious Diseases Flashcards
Most common cause of Otitis Externa
Pseudomonas aeruginosa
What is Antigenic Shift (and which virus does it occur in?)
Reassortment of viral genome from two different strains of Influenza B, leading to an abrupt change in structure/familiarity to immune system
What is antigenic drift?
Continuous mutations of haemagglutinin proteins, prevents formation of long lasting immune response to Influenza as specific IgA antibodies formed won’t continue to work
When is Oseltamivir most useful?
Only works in first 12 hours post infection, as well as in prophylactic role.
What organism is associated with UTI following bladder instrumentation?
Staphylococcus aureus
What’s the most sensitive test of osteomyelitis in diabetic foot infections?
Positive probe-to-bone test
Which antibiotics are best at penetrating biofilms?
Quinolones (Ciprofloxacin, norfloxacin, moxifloxacin)
Rifampicin
Linezolid
What beta lactams have high oral bioavailability?
Amoxicillin and Cephalexin
What organisms become more likely in an early acute PJI?
More likely to include gram negatives such as E coli and enterococci
Gold standard investigation for Malaria
Thick and thin films
Thick film: high sensitivity
Thin film: higher specificity, can determine species and density
Schuffner granules, crescent shaped granules
If negative, repeat 12-24hrly for 3 tests
Malaria antigen testing
Faster
Less sensitive
Doesn’t determine density
Can stay positive post treatment
Can have false negatives due to gene mutations
Most virulent Malaria species
Plasmodium falciparum
Dominant malaria species outside sub Saharan Africa
Plasmodium vivax
Markers of severe Malaria
High parasitaemia- >2%
Anaemia: Hb <50, Hct <0.20 with parasite count >10,000
Jaundice
Seizures
Kidney Injury
Shock
Impaired consciousness
Prostration
Hypoglycaemia <2.2mmol/L
