Infections and Antimicrobials Flashcards
What four factors needs to be considered when selecting an appropriate antibiotic?
Patient
Drug characteristics
Type of infection/causative organism
Society
What antibiotic is most appropriate for society?
One that is cheap, effective and minimises resistance
What are the advantages of narrow spectrum antibiotics?
Minimised disturbance to the normal gut flora
Minimises risk of superinfections
Avoids unnecessary selection pressure (–> causes resistance)
What is antimicrobial stewardship?
An organisation or healthcare-system wide approach to promoting and monitoring judicious use of antimicrobials to preserve their future effectiveness.
What is antimicrobial resistance?
Loss of effectiveness of any anti-infective medicine including antiviral, antifungal, antibacterial and anti parasitic medicines.
What should we consider before knowing if an antibiotic is indicated?
Is it likely to be BACTERIAL infection?
What can we do before prescribing antibiotics?
Is an antibiotic necessary?
What are some surgical interventions that can be done before prescribing antibiotics?
Removal of foreign material
Abscess drainage - difficult for antibiotics to get to centre of infection due to their being a lack of vasculature.
Debridement of infected tissue - removal of ulcer as this contains a majority of bacteria - reducing antimicrobial use and better penetration
Wound hygiene - keeping wounds clean and changing dressings
When may an antibiotic not be necessary?
Self limiting infections
If infection is VIRAL - only use antibiotics if there is a SECONDARY BACTERIAL INFECTION
Host defences function - antibiotics only needed in immunosuppressed patients.
What are the three types of evidence of infection?
Clinical , Laboratory and Imaging
What are some examples of clinical evidence of an infection?
Fever
Swelling
Pus
Tachycardia
Tachypnoea
Pain
What are some examples of laboratory evidence of an infection?
WBC count
CRP (inflammation)
Microscopy
Culture and sensitivity
What are some examples of imaging evidence of an infection?
X-ray (e.g. chest and lungs for signs of consolidation)
Ultrasound
MRI
CT
How can we ensure safe, rational and cost effective prescribing (FOR SOCIETY) using FROGS?
Formulary
Restricted list of antibiotics
Organisational policies - IV to oral, BROAD to NARROW, stop orders
Guidelines for EMPIRICAL treatment
Selective reporting of antibiotics sensitivities (e.g. checking sensitivity/resistance to first line treatment only)
What does APACHE II stand for and how does this help us select an appropriate antibiotic for the patient?
Age and gender (metabolism, side effects, likely conditions such as UTI in women)
Pregnancy/ breastfeeding
Antibiotic Exposure (e.g. do not want to give trimethoprim for UTI if already taking for prophylaxis)
Cautions/contraindications
Hypersensitivities/allergies
Elimination (hepatic and renal impairment)
Interactions (consider other medications)
Immunity (vaccine schedule, natural immune response, immunosuppression)
Which antibiotics are to be used with caution in epilepsy?
quinolones and imipenem : can lower seizure threshold
When are quinolones contraindicated?
Previous history of tendon disorders RELATED TO quinolone use.
If a patient has mild hypersensitivity to a penicillin what other antibiotics should be given in caution
cephalosporins - risk of cross sensitivity
If patient only experiences a mild rash may be able to give cephalosporins with an antihistamine BUT DO NOT GIVE IN ANAPHYLAXIS
Why are tetracylines contraindicated in children under 12?
Staining of teeth as it binds to calcium in teeth
Why are aminoglycosides contraindicated in myasthenia gravis?
Can impair neuromuscular transmission
What are two high risk antibiotics in renal impairment?
Aminoglycosides
Glycopeptides
Which antibiotics may require dose adjustment in hepatic impairment?
Chloramphenicol
Isoniazid
Metronidazole
Rifampicin
Which antibiotics should be avoided/ monitored closely in hepatic disease?
Macrolides
Co-amoxiclav (over 2 weeks use) and flucloxacillin
Which antibiotics can be affected by enzyme inhibitors?
Erythromycin
Clarithromycin
Isoniazid
Metronidazole
Ciprofloxacin
Which antibiotic can be affected by enzyme inducers?
Rifampicin - used in osteomyelitis and tuberculosis
Which antibiotics should not be taken with antacids/calcium?
Tetracyclines and quinolone
What antibiotics can interact with warfarin?
Broad spectrum antibiotics (can increase INR)
Which antibiotics are nephrotoxic?
Aminoglycosides
Glycopeptides
Colistin IF ALSO TAKING loop diuretics or ciclosporin
Which antibiotics can cause QT interval prolongation?
Erythromycin
Quinolones
Linezolid is a MAOI, what can it interact with?
Antidepressants (especially other MAOIs)
Tyramine rich foods should be avoided such as cheese, salami and marmite - can cause an increase in blood pressure.
When taking which antibiotic should the use of alcohol be COMPLETELY AVOIDED?
Metronidazole can cause:
severe vomiting
flushing/ redness
headache
What are some general side effects caused by most antibiotics?
Nausea
Vomiting
Diarrhoea
Rashes
Thrush
Aminoglycosides and glycopeptides ca cause which side effects?
nephrotoxicity and ototoxicity.
Clostridium difficile colitis can occur with which anitbiotics?
CLINDAMYCIN - any signs of diarrhoea STOP taking and go to GP
cephalosporins
Which antibiotics can cause chloestatic jaundice?
flucloxacillin and co-amoxiclav - monitor live function and look out for yellowing skin and pruritus.
How can peripheral neuropathy caused by isoniazid be minimised?
with pyridoxine
Limiting linezolid treatment to two weeks can help minimised the risk of…
Myelosupression
Why should macrolides be avoided in people with cardiac conduction disorders?
can cause QT interval prolongation
What side effect of rifampicin may worry patients but is usually harmless?
Bodily fluids turn red - urine may look bloody
Long term use of trimethoprim can result in…
Anaemia
Vacomycin can cause “Red Man” syndrome. How does this arise?
Vacomycin is normally given intravenously. If infused to quickly a reaction can occur leading to inflammatory vasodilation
Oral vancomycin can be used to treat which infection due to it not being absorbed well from the GI tract?
Clostridium difficile
What monitoring is required for aminoglycosides and glycopeptides?
Renal function - serum creatinine and urine output
Plasma drug levels (TDM) - high levels needed as killing is concentration dependent BUT need to be removed from body quickly.
What should be done to the dose and dose interval if giving an aminoglycoside in renal impairment?
Use a lower dose and increase dosing interval
WhWhat monitoring is required for rifampicin?
Liver function tests
What monitoring is required for long term use or high doses of flucloxacillin or co-amoxiclav?
Bilirubin and ALP - CAN CAUSE CHOLESTATIC JAUNDICE
What monitoring is required for Linezolid and septrin (co-trimoxazole)?
Full blood counts
Linezolid can cause myelosuppresion is used for more than 2 weeks
septrin (co-trimoxazole) contains Trimethoprim which can cause anaemia
What counselling must be given to patients starting clindamycin?
Stop taking treatment and see a healthcare professional if they get diarrhoea (risk of C.diff and toxic megacolon)
What does PS stand for and how can we use this to select an apporpriate antibiotic based on the infection?
Pathogen: what is the pathogen? Sensitivities? Resistant strains?
Severities: how unwell is the patient?
What types of bacteria commonly exist as part of the natural flora of the upper respiratory tract? MOSTLY GRAM POS
Staphylococcus (+)
Streptococcus (+)
Haemophilus (-)
Neisseria (-)
Anaerobes
Atypicals (mycoplasma)
Why do mycoplasma not have a gram stain?
because they are too small
What types of bacteria commonly exist as part of the natural flora of the upper respiratory tract? MOSTLY GRAM POS
Staphylococcus (+)
Coryne bacteria (diphtheroids)
Propionibacterium
What can happen after MRSA eradication?
MRSA can regrow so this should be considered in treatment.
What types of bacteria commonly exist as part of the natural flora of the genital tract?
Lactobacillus (-)
Streptococcus (+)
What types of bacteria commonly exist as part of the natural flora of the gastrointestinal tract? ANAEROBES and GRAM NEGATIVE
E.coli
Klebsiella
Lactobacillus
Streptococcus
Enterococcus
Candida
What does BRASS stand for and how can we use this to select an appropriate antibiotic based on the drug?
Bioavailability/ route
Resistance (look at local data)
Access to site of infection (e.g. drug for meningitis needs to reach CSF)
Spectrum/mechanism of action
Side effects
What are some broad spectrum antibiotics?
Amoxicillin
Chloramphenicol
Meropenem and Imipenem
Piperacillin
Tazobactam
Cephalosporins
Tetracyclines
Ciprofloxacin
Rifampicin
Nitrofurantoin
What are some narrow spectrum antibiotics that can target GRAM POSITIVE organisms?
Fusidic acid
Flucloxacillin
BEnzylpenicillin
Vancomycin
Clindamycin
Erythromycin
What are some narrow spectrum antibiotics that can target GRAM NEGATIVE organisms?
Gentamicin
Colistin
Trimethoprim
What antibiotic is commonly used against anaerobic pathogens (e.g. in dental abscesses or C.diff)
Metronidazole
How is antimicrobial stewardship achieved?
Promoting the selection of optimal antimicrobials, drug regimens, dose, duration and route of administration
What is WHO AwARe?
Splits antimicrobials into three groups.
Access
Watch
Reserve
What is the WHO ACCESS group?
first or second choice antibioticss
best therapeutic value with minimised potential for resistance
e.g. amoxicillin
What is the WHO WATCH group?
first or second choice anitbiotics BUT only indicated in a limited number of conditions as more likely to be a target of resistance
e.g. ceftriaxone
What is the WHO RESERVE group?
Last resort antibiotics for patients with life threatening infections and multi drug resistant bacteria
e.g. meropenem
What are the 5 categories in the Antimicrobial Stewardship toolkit for switching from IV to oral?
Timing - review every 24 hrs
Clinical signs and symptoms
Infection markers - Temp, EWS score, WBC
Special considerations - deep seated infections
Why is a patient’s antibiotic allergy status important?
May be non-allergy/ADR reported as allergy.
Ensure complete and accurate drug history is taken.
Penicillin allergy de-labelling where appropriate.
Morbidity, mortality and economic cost associated with penicillin allergy and may have to go from access or watch to reserve groups
