Antibiotics Flashcards
Which antibiotics are contraindicated in children?
Tetracyclines - not for < 12 years
Quinolones - cause arthropathy
Which antibiotics are contraindicated /cautioned in the elderly?
Clindamycin - highest risk of C. Diff
Careful in renal/liver impairment
Which antibiotics commonly cause allergic reactions?
Penicillins - also cross-sensitivity with cephalosporins and other B-lactam antibiotics
Which antibiotics can be used as alternatives in penicillin allergic patients?
Macrolides
Metronidazole (dental infections)
Which antibiotics cause nephrotoxicity?
Aminoglycosides
Glycopeptides
Which antibiotics should be avoided in renal impairment?
Tetracyclines - except minocycline/doxycycline
Nitrofurantoin - eGFR < 45
Which antibiotics cause hepatotoxicity?
Rifampicin
Tetracyclines
Reduce metronidazole dose if liver severely impaired
Which antibiotics cause cholestatic jaundice?
Co-amoxiclav
Flucloxacillin
Which antibiotics are contraindicated in pregnancy?
Tetracyclines
Trimethoprim
Nitrofurantoin - avoid at term as causes nausea
Which antibiotics should be avoided in pregnancy?
MCAT
Metronidazole, chloramphenicol, aminoglycosides, tetracyclines
Quinolones
Sulphonamides
Which antibiotics are safest in pregnancy?
Penicillins
Cephalosporins
What are the most common side effects of antibiotics?
GI
Nausea, vomiting, diarrhoea, abdominal pain
Which antibiotics can cause superinfection e.g. antibiotic associated colitis and thrush?
Clindamycin and broad spectrum antibiotics
C. Diff - antibiotics beginning with C most likely to cause, highest likelihood is clindamycin
Which of the following is most likely to be used in staphylococci infections?
A) Flucloxacillin B) Vancomycin C) Phenoxymethylpenicillin D) Metronidazole E) Gentamicin
A) Flucloxacillin
Which of the following is most likely to be used in MRSA infection?
A) Flucloxacillin B) Penicillin V C) Metronidazole D) Tazosin E) vancomycin
E) Vancomycin
Which of the following is most likely to be used in streptococci infection?
A) Phenoxymethylpenicillin B) Erythromycin C) Metronidazole D) Gentamicin E) Flucloxacillin
A) Phenoxymethylpenicillin
Which of the following is most likely to be used in anaerobic infection?
A) Gentamicin B) Metronidazole C) Cefalexin D) Flucloxacillin E) Benzylpenicillin
B) Metronidazole
Which of the following is most likely to be used in pseudomonas aeruginosa infection?
A) Flucloxacillin B) Vancomycin C) Metronidazole D) Gentamicin E) Trimethoprim
D) Gentamicin
What is the mechanism of action for clindamycin?
Inhibits protein synthesis
Narrow spectrum
Bacteriostatic
What are the most common side effects of clindamycin?
Antibiotic associated colitis
Most common in middle aged, elderly women, especially after operations
What is the patient counselling needed for clindamycin?
If diarrhoea develops stop and see GP
Which antibiotics reduce the efficacy of COCs?
Impairs bacterial flora responsible for recycling ethinylestradiol
Ampicillin
Amoxicillin
Doxycycline
Additional precautions required for duration of treatment and 7 days after stopping
What is the mechanism of action of linezolid?
Inhibits protein synthesis
Only active against gram positive bacteria e.g. MRSA and anaerobes
Narrow spectrum
Bacteriostatic
What is an alternative to vancomycin when used for MRSA infection?
Linezolid
What are the side effects of linezolid?
Blood disorders
Optic neuropathy if > 28 days use
What is the patient counselling needed for linezolid?
Report visual symptoms
Blurred vision, visual field defects, changes in visual acuity and colour vision
What are the important interactions for linezolid?
Hypertensive crises - SSRI, TCA, MAOI (wait 2 weeks after stopping), opioids, 5HT agonists, buspirone, pethidine
Linezolid is a reversible MAOI
Avoid consuming large amounts of tyramine rich foods e.g. cheese, cured meats
What is the mechanism of action for trimethoprim?
Inhibits DNA synthesis
Narrow spectrum
Bactericidal
What is trimethoprim used for and what dose?
UTI
200mg BD
What are the important side effects of trimethoprim?
Anti-folate - teratogenic in first trimester
Blood dyscrasias - with long term use
Hyperkalaemia
Most important interaction for trimethoprim?
Methotrexate - DO NOT USE
What is co-trimoxazole used for?
Trimethoprim/sulfamthoxazole
Prophylaxis and treatment of pneumocystis jirovecii pneumonia
What are the side effects for co-trimoxazole?
Rashes, necrolysis, photosensitivity
What are the counselling points for trimethoprim?
Blood dyscrasias - report fever, sore throat, rash, mouth ulcers, purpura, bruising, bleeding
What is the mechanism of action for chloramphenicol?
Inhibits protein synthesis
Broad spectrum
Bacteriostatic
When is chloramphenicol used?
Bacterial conjunctivitis OTC
Life-threatening conditions
What are the side effects of chloramphenicol?
Blood dyscrasias
Grey baby syndrome - avoid in pregnant women
Unlikely to occur with eye drops but eye drops unlicensed for use in pregnant women OTC
What is the dosing regime for chloramphenicol eye drops for bacterial conjunctivitis OTC?
5 day course, if no improvement within 48 hours discontinue and seek medical advice
Optrex - one drop every 2 hours for the first 48 hours and 4 hourly thereafter. Use for 5 days even if symptoms improve
What age can chloramphenicol eye drops be used OTC?
Over the age of 2 as it contains boron which may impair fertility in the future
What is the dosing regimen for chloramphenicol ointment OTC?
Apply approximately 1 cm of ointment between the lower eyelid and the eye 3-4 times a day
What time of day chloramphenicol eye drops and eye ointment be used if using together?
Drops used during the day
Ointment used at night
Does chloramphenicol ointment need to be stored in the fridge?
No
Do chloramphenicol eye drops need to be stored in the fridge?
Yes
What is the mechanism of action for metronidazole?
Inhibits DNA synthesis
High activity against anaerobic bacteria and protozoa
Narrow spectrum and bactericidal
What is metronidazole used for?
Anaerobic infections e.g. dental, antibiotic associated colitis, h. Pylori, rosacea, bacterial vaginosis
Protozoal infections e.g. vagina, trichomoniasis, giardiasis
What are the common side effects of metronidazole?
GI disturbances, taste disturbances, oral mucositis, furred tongue
What are the counselling points for metronidazole?
Take with or after food
AVOID alcohol as it causes a disulfiram-like reaction
What is the mechanism of action for nitrofurantoin?
Damages bacterial DNA
Only active against urinary pathogens
Narrow spectrum
Bactericidal
What are the uses of nitrofurantoin?
UTIs
What are the side effects of nitrofurantoin?
Nausea
Peripheral neuropathy in renal impairment
Can nitrofurantoin be used in pregnancy?
Yes, but avoid at term as causes neonatal haemolysis
What are the contraindications for nitrofurantoin?
Infants less than 3 months
What are the counselling points for nitrofurantoin?
Take with or after food
Colours urine YELLOW or BROWN
What are the aminoglycosides?
Gentamicin Tobramycin Streptomycin Neomycin Amikacin
What is the mechanism of action of aminoglycosides?
Bind irreversibly to bacterial ribosomes
Active against gram negative aerobe pseudomonas aeruginosa
Broad spectrum
Bactericidal
What are the aminoglycosides used for?
Severe sepsis
Pyelonephritis
Complicated UTI
Endocarditis
Why are aminoglycosides given parenterally?
They are not absorbed by the gut
Which of the following aminoglycosides is most likely to be used for pseudomonas aeruginosa infection?
A) Amikacin B) Neomycin C) Gentamicin D) Streptomycin E) Tobramycin
C) Gentamicin
Which of the following aminoglycosides is most likely to be used via an inhaler for pseudomonal infection in cystic fibrosis?
A) Amikacin B) Neomycin C) Gentamicin D) Streptomycin E) Tobramycin
E) Tobramycin
Which of the following aminoglycosides is most likely to be used in TB?
A) Amikacin B) Neomycin C) Gentamicin D) Streptomycin E) Tobramycin
D) Streptomycin
Which of the following aminoglycosides is most likely to be used in bowel sterilisation?
A) Amikacin B) Neomycin C) Gentamicin D) Streptomycin E) Tobramycin
B) Neomycin
Neomycin is parenterally toxic
Which of the following aminoglycosides is most likely to be used for gentamicin-resistant gram-negative bacilli?
A) Amikacin B) Neomycin C) Gentamicin D) Streptomycin E) Tobramycin
A) Amikacin
What is gentamicin used for?
Active against pseudomonas aeruginosa
Blind therapy in serious infection - with metronidazole/penicillin
What are the monitoring requirements for gentamicin?
Plasma concentrations - narrow therapeutic index
Serum concentration in: Elderly Obesity Cystic fibrosis High doses Renal impairment
When do you avoid a once daily dosing of gentamicin?
Avoid in renal impairment < 20ml/min, HACEK or gram positive endocarditis, burns covering > 20% of body