antibiotic matching 2 Flashcards
Why can the antibiotic guidelines not always be relied on for choosing which antibiotic to use for treatment?
The guidelines will tell you what to do for a “standard” patient
not all patients are the same, so antibiotic treatment often needs to be individualised
Why does antibiotic treatment often need to be individualised?
- 10% of patients are allergic to penicillin
- some drugs should be avoided in the elderly e.g. ciprofloxacin
- some patients can’t take oral / IV antibiotics
- patients with renal impairments need to avoid taking nephrotoxic drugs
- Microbiology culture results may allow narrowing of the spectrum of antibiotics or may dictate a new antibiotic choice
- don’t want to exacerbate problems e.g. don’t give a macrolide to a patient with diarrhoea
- some antibiotics may interact with drugs that a patient is already taking
If a patient presents with a fever, what should you consider?
Fever is caused by infections
you need to think about what is probable and not what is possible
nearly every infection causes a fever, but a lot of infections are very unlikely
What is meant by the pre-test probability of differential diagnoses?
How likely are each of the possible infections, even though no tests have been performed on the patients yet
this helps to inform history and examination and dictate which tests need to be performed
What are the 3 different types of diagnoses?
Diagnosis:
- this is the final decision about the condition that the patient has
Differential diagnosis:
- this involves 3 or 4 possible infections which may be causing the symptoms
Working diagnosis:
- you are not entirely sure what is causing the infection, but you need to start treatment immediately whilst you wait to confirm what is causing the infection
What tests are needed to work towards a diagnosis?
- History
- examination
- laboratory tests
- radiological tests
- trial without therapy
- trial of therapy
When going through a systematic history, which systems should be looked at?
- Central nervous system
- respiratory system
- cardiovascular system
- genitourinary system
- skin and soft tissue
- abdominal system
- other - e.g. recent antibiotic use
What does NAD stand for?
Nothing abnormal detected
Can the differential diagnosis include low probability infections?
Why?
Your need to consider conditions with poor prognosis, even if they are unlikely
e.g. It is unlikely that a patient has meningitis, but if this is missed, the patient will go on to have a very poor prognosis
Which tests are performed initially?
How is this decided?
Pick the tests that are quick and easy to do
e.g. Blood cultures are performed on every patient
once the initial results come back, these can be used to determine whether more invasive tests need to be performed
What is the definition of diagnostic iteration?
A procedure in which repetition of a sequence of operations (tests) yields results successively closer to a desired result (a high diagnostic probability)
What is meant by bacteria-antibiotic matching?
Which bacteria do you need to cover based on your working diagnosis?
Which anti-bacterials or anti-bacterial combinations will cover all of these possible bacteria?
What are the pathogens which are capable of causing community acquired pneumonia?
Gram positive cocci:
- streptococcus pneumoniae
gram negative cocci:
- moraxellas cattharalis
gram negative rods:
- Haemophilus influenza
no cell wall:
- legionella pneumophilia
- mycoplasma pneumoniae
- chlamydia pneumoniae
Which antibiotics can be used against the different CAP pathogens?
tick:
- the antibiotic at usual doses against wild type bacteria will be likely to result in clinical cure
cross:
- the antibiotic at usual disease against wild type bacteria will have a reduced likelihood of resulting in clinical cure
What do the red boxes represent?
What would be given in a patient with CAP and post-viral pneumonia?
Red boxes indicate resistance as a result of methicillin resistance in MRSA
vancomycin would be given
ciprofloxacin or doxycycline would be given alongside this
after receiving the sputum results, you may just be able to give vancomycin alone if you know exactly what the cause is
Which antibiotics tend to be prescribed in urinary tract infections (cystitis)?
What things should be taken into consideration?
- To allow someone to be discharged quickly, there is a request for oral antibiotics to be prescribed
- some antibiotics are not suitable in systemic infection (upper UTI) as they are concentrated in the bladder
What is meant by penicillinase, ESBLs and CPEs?
What antibiotics can be used to treat all these conditions?
Penicillinases:
- these enzymes break down penicillins, so amoxicillin is not effective
- cefuroxime and meropenem can be used
ESBLs:
- extended spectrum beta lactamases break down amoxicillin and cefuroxime
- meropenem can be used
CPEs:
- these break down carbapenems so amoxicillin, cefuroxime and meropenem are not effective
- they are resistant to all commonly used antibiotics
What antibiotics can be used in a UTI with an ESBL susceptibility profile?
With an ESBL, a lot of first and second line beta lactam antibiotics can’t be used
What UTIs can be used in a UTI with an ESBL susceptibility profile with additional resistance?
Carbapenems can be used, but most commonly used antibiotics are not effective against these bacteria
What does CPE stand for?
What types of antibiotics can be used in a UTI with a CPE bacteria?
Carbapenemase producing enterobacteriaceae
It is resistant to all commonly used antibiotics and is a major challenge in healthcare globally
