Microbiology Flashcards
1st line antibiotic prophylaxis for animal/human bites?
Co-Amoxiclav
What antibiotics are given as part of ‘quadruple therapy’ for TB ?
Rifampicin + Isoniazid + Pyrizinamide + Ethambutol
(RIPE)
What is a significant side effect of ethambutol and what is given to reduce the risk of this?
Optic neuropathy / colour blindness. Vitamin B6 is given concurrently to reduce the risk.
True or false - Rifampicin can make bodily secretions orange?
True
What is the first line treatment for a case of a first presentation of genital herpes (herpes simplex)?
For 1st episode of genital herpes = 1st line is oral aciclovir (or oral valaciclovir or famciclovir) if within 5 days of symptoms beginning OR if new lesions are still forming. Pts with concurrent advanced HIV may need double the dose of the oral antivirals.
What is the optimal management of recurrent / subsequent attacks of genital herpes (herpes simplex)?
Repeat attacks of genital herpes tend to become less severe, shorter and less frequent with time. Typically just advise avoiding trigger factors (sunlight, intercourse) and self-care measures. If this fails to control symptoms consider either 1) Episodic management (if they have <6 episodes per year) - with oral antivirals at the onset of symptom OR 2) Prophylaxis if 6 or more episodes per year, causing psychological distress or affecting social life (with oral antiviral for 1 year then stop to see if recurrence)
What bacteria causes lyme disease and how is it transmitted?
Borrelia burgdorferi
Transmitted through the bite of an infected tick. Highest prevalence in the UK is in Scottish highlands + South of England but can get anywhere.
How should you manage patients that have been recently bitten by a tick but are asymptomatic?
Most tick bites don’t transmit Lyme disease - if they are asymptomatic and have promptly removed the tick no investigation or treatment is needed.
Presentation with which rash is diagnostic of lyme disease?
Erythema migrans.
= A red rash, normally at the site of the tick bite, that increases in size and sometimes has a central clearing. Can occur anywhere from a few days to a few weeks after the original bite and usually lasts a few weeks. NOT PAINFUL OR ITCHY.
A rash that arises immediately after the bite and recedes within 48 hrs that IS itchy/painful is likely not Lyme disease / erythema migrans but more focal infection with commensal skin bacteria following the bite.
If a patient presents with erythema migrans, do you need to do lab investigations to confirm borrelia burgdorferi?
NO!
Erythema migrans is diagnostic and you can start Tx.
How would you investigate patients without erythema migrans but for whom you have a high clinical suspicion of Lyme disease (tick bite and symptomatic - fever, lymphadenopathy, fatigue, brain fog, fluctuating + migratory polyarthropathy, neurological symptoms unexplained facial or other CN palsy, mononeuritis multiplex (peripheral neuropathy in 2 or more different nerve areas), uveitis, keratitis, pericarditis (lyme carditis)
Initial test = ELISA test for Lyme disease.
If ELISA positive = then do an immunoblot test.
If ELISA neg = doesn’t exclude lyme disease if high clinical suspicion. Repeat the ELISA in 4-6 weeks if the 1st one was done within 4 wks of the onset of symptoms. If remains neg and clinical suspicion high then do immunoblot.
Can start treatment prior to ELISA results if high clinical suspicion.
What are the 1st line antibiotic treatments for Lyme disease?
Adults / >9 yrs: Oral doxycycline for 3-4 weeks (if pregnant or allergic to doxy = oral amoxicillin)
OR IV ceftriaxone if haemodynamically unstable or affecting the CNS.
Children <9: oral amoxicillin OR IV Ceftriaxone if haemodynamically unstable or affecting the CNS.
Can repeat the course if ongoing symptoms / evidence of re-infection but do not routinely offer more than 2x courses of abx for lyme disease.
What is a significant side effect of isoniazid (given as part of quadruple therapy for TB) and what is given alongside to reduce the risk?
Peripheral neuropathy
Vit B6 supplementation is given alongside to reduce the risk.
What is a significant side effect of Pyrazinamide (used as part of quadruple therapy for TB)?
^ uric acid levels / gout
What is the causative organism behind rubella / german measles?
Togavirus.
What is Hutchinson’s sign as it pertains to shingles?
Hutchinson’s sign = shingles rash extending to the tip of the nose = high risk of corneal involvement because the nasociliary branch of the trigeminal nerve supplies both the cornea and the tip of the nose.
