Infections Part 1 Flashcards
Principles of Antimicrobial Stewardship
- Do not treat viral infection with antibiotics
- avoid blind prescribing
- narrow spectrum antibiotics preferred, unless serious infection
- avoid long course and complete course
- follow prescribing guidelines
- dose varies according to patient factors
Patient factors that need attention when prescribing antibiotics
- Age
- Allergies
- Renal Impairment
- Hepatic Impairment
- Pregnancy
Patient needs in Antibiotic prescribing:
Children
- Tetracyclines contraindicated in under 12
- Quinolones cause arthropathy, so avoid
Patient needs in Antibiotic prescribing:
Elderly
- Increased risk of Clostridium Difficile infection; Clindamycin has highest risk
- Be aware of renal/liver impairment and drug interactions
Patient needs in Antibiotic prescribing:
Allergies
Penicillin-allergic = cross sensitivity with Cephalosporins and other B-lactam antibiotics
Alternatives to penicillin:
- Macrolides
- Metronidazole (dental)
Patient needs in Antibiotic prescribing:
Renal Impairment
- avoid tetracyclines
- avoid Nitrofurantoin if eGFR <45
Patient needs in Antibiotic prescribing:
Hepatic Impairment
Rifampicin and Tetracyclines
- reduce metronidazole dose if severely impaired
Cholestatic jaundice:
- co-amoxiclav
- flucloxacillin
Patient needs in Antibiotic prescribing:
Pregnancy
Tetracyclines and Trimethoprim contraindicated
Nitrofurantoin causes nausea and vomiting (avoid at term)
Avoid Quinolones, Sulphonamides and MCAT:
- Metronidazole
- Chloramphenicol
- Aminoglycosides
- Tetracyclines
(safest antibiotic is Penicillin/Cephalosporin)
What is the antibiotic cautionary and advisory label
Space the doses evenly through the day and finish the course unless told to stop
Antibiotic gastro-intestinal side effects
- Nausea
- Vomiting
- Diarrhoea
- Abdominal pain
What is superinfection
Broad spectrum antibiotics and Clindamycin kills all flora. This allows selective organisms to thrive: causing antibiotic associated colitis and thrush
What medication manages Staphylococci
Flucloxacillin
What medication manages MRSA
Vancomycin
What medication manages Streptococci
Benzylpenicillin or phenoxymethylpenicillin
What medication manages Anaerobic bacteria
Metronidazole
What medication manages Pseudomoans Aaeruginosa
Gentamicin
Clindamycin mode of action
Inhibits protein synthesis
(narrow spectrum)
(bacteriostatic)
Side Effects of Clindamycin
- antibiotic associated colitis
- especially after operation
Counselling:
if diarrhoea develops: stop and see GP
Linezolid mode of action
Inhibits protein synthesis. Only effective on gram-positive bacteria
(Narrow-spectrum)
(bacteriostatic)
What antibiotic is an alternative to vancomycin in MRSA infection
Linezolid
Side Effects of Linezolids
- Blood disorders
- optic neuropathy (above 28 day use)
Counselling:
- report visual symptoms
(blurred vision, visual field defects and changes in visual activity)
avoid foods with high tyramine levels
What drugs react with Linezolids to increase hypertensive crisis
- SSRIs
- TCAs
- MAOIs
- Dopaminergics
- Opioids
- 5-HT agonists
- Buspirone
- Pethidine
Trimethoprim mode of action
Inhibits DNA synthesis
(narrow spectrum)
(bacteriostatic)
Trimethoprim side effects
- Anti-folate (teratogenic in first trimester)
- Blood dyscrasias (long term use)
- Hyperkalaemia
What is Co-Trimoxaxole
Trimethoprim and Sulfamethoxazole
Indication of Co-Trimoxaxole
Prophylaxis and treatment of pneumocystis jirovecii pneumonia.
Side effects of Co-Trimoxaxole
- Steven Johnson Syndrome toxic toxic epidermal necrolysis
- Photosensitivity
Chloramphenicol mode of action
inhibits protein synthesis
(broad-spectrum)
(bacteriostatic)
Chloramphenicol indication
reserved for life-threatening infections
- Blood dyscrasias
- Grey baby syndrome (avoid in pregnant women)
Metronidazole mode of action
Inhibits DNA synthesis. High activity against anaerobic bacteria and protozoa
(narrow-spectrum)
(bactericidal)
Metronidazole indications
- Anaerobic infections
(dental, antibiotic colitis, h.pylori, rosacea, bacterial vaginosis) - Protozoal Infections
(vaginal trichomoniasis, giardiasis)
Metronidazole side effects
- gastro-intestinal disturbances, taste disturbances, oral mucositis, furred tounge
Metronidazole patient counselling
- take with or after food
- avoid alcohol (causes disulfiram-like reaction)
Nitrofurantoin mode of action
damages bacterial DNA. Only targets active urinary pathogens
(narrow spectrum)
(bactericidal)
Side effects of Nitrofurantoin
- Nausea
- Risk of peripheral neuropathy in renal impairment
Nitrofurantoin and pregnancy
Avoid at term (37 to 42 weeks) (causes neonatal haemolysis)
Nitrofurantoin contraindications
Infants less than 3 months
Nitrofurantoin patient counselling
- take with or after food
- colours urine yellow or brown
Aminoglycosides
Binds irreversibly to bacteria ribosomes. Active against gram-negative aerobe; Pseudomonas aeruginosa
(Broad spectrum)
(Bactericidal)
Examples of Aminoglycosides Part 1
- Gentamicin (Pseudomonas aeruginosa)
- Tobramycin (inhaled for Pseudomonas aeruginosa in cystic fibrosis)
- Streptomycin (for mycobacterium for TB)
Examples of Aminoglycosides Part 2
- Neomycin (for bowel sterilisation, parenterally toxic)
- Amikacin (for gentamicin resistant gram-negative bacilli)
Gentamicin (Aminoglycosides) mode of action
Active against Pseudomonas Aeruginosa. Blind therapy in serious infection with metronidazole/penicillin
What therapeutic index does Gentamicin have
Narrow
Monitoring with Gentamicin and aminoglycoside use
Monitor serum levels in…
- parental ahminoglycosides use
- Elderly
- Obesity
- Cystic fibrosis
- High doses
- Renal Impairment
Aminoglycoside once daily dose regimen, when to avoid
- renal impairment (<20ml/min)
- HACEK
- Gram-positive endocarditis
- Burns convering more than 20% of body
When to increase dose interval of Gentamicin
- when renal impairment
- if serum levels pre-dose are too high
When to reduce dose of Gentamicin
- if post-dose serum level after 1 hour is too high
- in severe renal impairment (<30ml/min)
Pregnancy and Gentamicin
- avoid unless essential
- must monitor serum concentrations
Aminoglycosdies and nephrotoxicity
- Aminoglycosdies are excreted by kidney
- Assess renal function before treatment and correct any dehydration
Signs of Nephrotoxicity:
- Low urine output/creatinine clearance
- High creatinine/urea serum conc
Aminoglycosdies and Ototoxicity (hearing/balance loss)
monitor auditory and vestibular function before treatment
Patient counselling:
report hearing loss, tinnitus, vertigo
What drugs interact with Aminoglycosdies to increase risk of nephrotoxicity
- Ciclosporin
- Tacrolimus
- Vancomycin
What drugs interact with Aminoglycosdies to increase risk of Ototoxicity
- Loop diuretics
- Cisplatin
(if taking loop diuretics is needed, separate use by long period)
Other Side effects of Aminoglycosdies
- Peripheral neuropathy
- Impaired neuromuscular transmission
- Electrolyte imbalance (too much: K, Ca, Mg)
Glycopeptides mode of action
Inhibits cell wall synthesis. Only active against gram-positive bacteria including MRSA
(narrow spectrum)
(Bactericidal)
What examples of Glycopeptides
- Vancomycin (MRSA)
- Teicoplanin
- Televancin
Vancomycin and Teicoplanin not be given by mouth for systemic infections
Vancomycin indications
- Antibiotic-associated colitis
- MRSA
(Paternally injected for serious infections)
What is the therapeutic index for Vancomycin
Narrow
Vancomycin Monitoring
- serum conc for all patients (after 3 to 4 doses and dose change)
- If in renal impairment (earlier and more regular monitoring) = reduce dose
- Pre dose level= 10-15mg/ml
- Pre dose level for endocarditis or MRSA= 15-20mg/ml)
Pregnancy and Vancomycin
avoid in pregnancy unless essential
need to monitor serum conc
Side Effects of Glycopeptides
- Nephrotoxicity
- Ototoxicity
- Red mans syndrome
- Blood dyscrasias
- Skin disorders
- Thrombophlebitis
What is red mans syndrome
flushing of the upper body caused by rapid infusion and can be associated with hypotension and bronchospasm
Examples of Blood Dyscasias
- Netropoenia
- Thrombocytopenia
- Agranulocytis
Examples of skin disorders with Glycopeptides
- Steven-Johnson syndrome
- Itching
- Rashes
- Toxic epidermal necrolysis
what is Thrombophlebitis
pain and inflammation of veins
(usually at infusion lights)
