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Flashcards in Infectious Disease Deck (53)
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What causes scarlet fever?

Streptococcus pyogenes


You are a surgical house officer and have been bleeped to see a 34 year old man who is post op day 1 following abdominal surgery. He complains of intense pain around his leg. On examination it is erythematous. His temperature is 38.3, HR 160, BP 135/96. He is a known diabetic and heavy drinker. What is the most appropriate management?

IV morphine and urgent referral for surgical debridement
This patient has necrotising fasciitis


What are risk factors for necrotising fasciitis?

Abdominal surgery


What 4 drugs are used to treat TB?



What is a main side effect of ethambutol? What should be done before commencing treatment?

Toxic optic neuropathy
Test visual acuity and colour vision before treatment


What test should be performed prior to commencing rifampicin, isoniazid and pyrazinamide treatment?

LFTs as they can cause hepatitis


What type of bacteria is E.coli?

Gram negative bacilli


What is infectious mononucleosis?

Glandular fever
Self limiting infection due to Epstein Barr virus
Low grade fever, sore throat, lethargy


How do you diagnose glandular fever?

Monospot test


What happens if you prescribe amoxicillin to patients with glandular fever?

Severe rash


What is leptospirosis?

Weils disease
Infection caused by spirochaetes
Due to contact with infected urine, usually from rats
Mild flu like symptoms, jaundice, meningitis and renal failure in severe cases


How long after HIV exposure is post exposure prophylaxis effective for?

Most effective within an hour of infection
After 72 hours, effectiveness is very limited


What are the 3 most common chase of lung infection in people with cystic fibrosis?

Staph aureus
Haemophillus influenza
Pseudomonas aeruginosa: rusty coloured sputum


What sort of infections are people with a splenectomy susceptible to? And why

Encapsulated organisms for example h. Influenza and strep pneumoniae
Because spleen provides environment where encapsulated organisms are opsonised


What is antimicrobial stewardship?

Organisational approach to promoting and monitoring judicious use of antimicrobials to preserve their future effectiveness


What are the principles of antimicrobial stewardship?

How: Prescribe only when needed, Review need for abx in accordance with local formularies and guidelines
Why: Optimise therapy for individual patients, Prevent overuse, misuse, abuse, Minimise development of resistance at patient and
community levels


Who has responsibility for antimicrobial stewardship?

Society: Demand and supply


Why is antimicrobial stewardship important?

Optimise therapy for individual patients
Minimise side effects
Microbiome: all antibiotics, limit with narrower spectrum
Allergy and intolerance, specific contraindications and interactions
Prevent overuse, misuse, abuse
Minimise development of resistance at patient and community levels


How can we limit the need for antimicrobials?

Prevention and control of infection: No infection means no antibiotic needed, No multi-resistant organism means narrower spectrum antibiotic can be used


List resources available to aid optimal antimicrobial prescribing

TARGET antibiotics toolkit: treat antibiotics responsibly guidance, education and tools
NICE guidelines
Department of health antimicrobial stewardship guide
Local primary and secondary care guidance


What is contained in the TARGET toolkit?

Commissioner resources
Information for patients
Audit tools
Training resources
Self assessment
National antibiotic management guidance


List the principal considerations required before commencing antibiotic therapy

Absorption (How can I get it into my patient?)
Distribution (does it get where I want it to?)
Predictably sensitive? (is resistance likely to be a problem before or after treatment?)
Adverse effects (common, particular patient group?)
Interaction with other drugs (prescribed or otherwise)
Metabolism and excretion (how does the drug get out? Is that a problem in my patient?)


What are beta lactam antibiotics?

Penicillins and their derivatives
Cephalosporins (ceph/ cef….)
Carbapenems (-penems)
Monobactams (aztreonam)


Describe the absorption profiles of the beta lactam antibiotics

Penicillins: Penicillin V/ phenoxymethylpenicillin low absorption from GI tract, Amoxicillin better, Penicillin G/ benzylpenicillin no absorption so given IV
Cephalosporins: Limited number available orally, generally good absorption for those that are (cefalexin), Most IV only e.g. ceftriaxone
Carbapenems: No oral formulation
Aztreonam: Also IV only


Describe the distribution profile of beta lactam antibiotics

Generally good penetration to body tissues
Penicillins don’t cross the blood-brain barrier well unless the meninges are inflamed
Do not get inside individual host cells
Poor activity against bacteria that live intracellularly, Legionella is classic example


Describe the mechanism of action of beta lactam antibiotics. What implication does this have?

Interruption of cell wall synthesis
So NO activity against bacteria without a cell wall (Mycoplasma, Chlamydia)


What is the difference between a bacteriostatic and bacteriocidal antibiotics?

Bacteriostatic: inhibiting the growth of a bacterium
Bactericidal: killing the bacterium


What is the minimum inhibitory concentration?

Lowest concentration of an antibiotic which inhibits visible growth of bacteria


What is minimum Bactericidal concentration?

Lowest Concentration of an antibiotic that kills 99.9% of a population of bacteria


What is the breakpoint in terms of antibiotic sensitivity?

Minimum inhibitory concentration cut-off which separates strains where there is a high likelihood of treatment succeeding from those where treatment is more likely to fail