Infections Flashcards
Are narrow- spectrum antibacterials preferred or broad- spectrum?
Narrow- spectrum preferred
UNLESS it is clear clinically whats causing infection
Thats why you should test to see what organism is causing it
What does the dose of antibacterial drugs depend on? (5)
- age
- weight
- hepatic function
- renal function
- severity of infection
What does the route of administration of an antibacterial drug depend on? (1)
severity of infection
What route of administration is usually used for life- threatening infections? (1)
IV
What does duration of therapy depend on? (2)
- type of infection
- the response of the infection to treatment
What are the disadvantages of un needed prolonged courses of antibacterial drugs? (3)
- encourage resistance
- may lead to side- effects
- costly
What types of antibacterials are suitable for use during pregnancy? (3)
- penicillins
- cephalosporins
- nitrofurantoin may be used BUT avoid at term
What antibacterials should be avoided during pregnancy? (3)
- diaminopyrimidines
- quinolones
- trimethoprim PARTICULARLY in 1st trimester
What antibacterials should be avoided in renal impairment? (2)
- tetracyclines
- nitrofurantoin
If wanting to give aminoglycosides to someone with renal impairment, what must be done? (2)
Reduce the dose
As aminoglycosides are excreted by the kidney
Provide some examples of aminoglycosides: (5)
- amikacin
- gentamicin
- neomycin
- streptomycin
- tobramycin
What is the mechanism of action of aminoglycosides? (4)
Bactericidal
Irreversibly binding to ribosomes
Inhibit protein synthesis
Causes fissure which ENHANCES UPTAKE of ANTIBIOTIC & LEAKAGE of cell contents
What type of bacteria are aminoglycosides active against? (2)
Broad- spectrum
Mostly against Gram - ve
But also some Gram + ve
What are the indications of aminoglycosides? (4)
- CNS infections: endocarditis, septicaemia, meningitis
-Biliary-tract infection
- Prostitis
- Pneumonia
Which aminoglycosides are active against P. aeruginosa? (3)
Amikacin, Tobramycin and Gentamicin
Which aminoglycoside is active against M. tuberculosis? (1)
Streptomycin
What are side effects of aminoglycosides? (8)
- may impair neuromuscular transmission
- irreverisible ototoxicity
- nephrotoxicity
- nausea
- vomiting
- antibiotic associated colitis
- peripheral neuropathy
- electrolyte disturbances
MINNVAPE
Which patients should we take caution in when giving aminoglycosides? (1)
And we should also take caution when pts taking aminoglycosides with what drugs? (2)
caution in patients with clinical muscular weakness, e.g. myasthenia gravis
avoid concomitant use with ototoxic drugs, e.g. cisplatin and furosemide
avoid concomitant use with nephrotoxic drugs e.g. vancomycin and ciclosporin
What are examples of ototoxic drugs?
cisplatin and furosemide
What are examples of nephrotoxic drugs?
vancomycin and ciclosporin
Why are aminoglycosides given parenterally for systemic infections?
they are not absorbed from the gut
Although aminoglycosides are given parenterally, neomycin can be given orally for two indications. What can neomycin be given orally for? (2)
bowel sterilisation before surgery
liver failure
Are once-daily doses of aminoglycosides preferred over multiple daily doses?
Yes
What is the aminoglycoside of choice in the UK?
Gentamicin
What is the therapeutic range of gentamicin like?
Narrow
What should the post- dose (peak) serum concentration be for multiple daily dose regimens of gentamicin?
How would this change in endocarditis? (2)
Measured one hour after dose
5- 10mg/ L
3 - 5 mg/L for endocarditis
(High levels suggest potential toxicity; reduce the dose accordingly)
What should the pre- dose (trough) concentration be for multiple daily dose regimens of gentamicin?
How would this change in endocarditis? (2)
This is measured just before the next scheduled dose.
< 2mg/ L
<1mg/ L for endocarditis
High levels suggest inadequate drug clearance; adjust dosing interval.
What should we monitor in all aminoglycosides? (3)
Renal function (as can cause nephrotoxicity)
Auditory and vestibular function (as can cause irreversible ototoxicity)
Serum- aminoglycoside in certain groups of patient
In which patients should serum- aminoglycoside concentration be determined? (6)
Elderly
Those receiving parenteral treatment
Renal impairment
Obesity
Cystic fibrosis
Those receiving high doses
What warning signs should patients on aminoglycosides look out for and what should they do if they see these signs?(3)
Nephrotoxicity
Ototoxicity (hearing impairment or disturbance)
Dehydration (ensure patient is well hydrated before treatment to prevent dehydration)
If these signs are seen, patients should REPORT all to their doctor immediately.
Can aminoglycosides be given in pregnancy? (2)
Risk of auditory and vestibular nerve damage in 2nd and 3rd trimester
Avoid unless essential
What are drug interactions of aminoglycosides? (2)
Increased risk of ototoxicity when given with furosemide (loop diuretics), vancomycin,cisplatin
Increased risk of nephrotoxicity when given with ciclosporin, tacrolimus, vancomycin
What are signs of nephrotoxicity? (2)
Low urine output/creatinine clearance
high serum creatinine/urea
(Make sure to assess renal function of patient before treatment; correct dehydration)
What reaction can some batches of aminoglycosides cause? (3)
histamine-related adverse drug reactions
Monitor for signs of histamine-related reactions
Exercise caution with concomitant drugs known to cause histamine release, especially in children and severe renal impairment.
What are the five generations of cephalosporins? (4)
1st cefalexin, cefradine, cefadroxil (bd)
2nd cefaclor, cefuroxime
3rd cefixime, ceftriaxone
5th ceftaoline fosamil
What is the mechanism of action of cephalosporins? (3(
Bactericidal
Prevent cell wall synthesis
By binding to enzymes called penicillin binding proteins (PBPs)
What types of bacteria are cephalosporins active against? (1)
Both Gram -ve and Gram +ve
What indications are cephalosporins given for?(4)
Pneumonia
Meningitis
Gonorrhoea
UTIs
What are the side effects of cephalosporins?
Antibiotic associated colitis (rare but more common with 2nd and 3rd generation)
Which generations of cephalosporins tend to be given orally?
1st and 2nd
Which generation of cephalosporins tend to be given parenterally? Which one is an exception? (2)
3rd and 5th
except for cefixime in the 3rd generation, which is orally active
Cephalosporins should not be administered to individuals with a history of what hypersensitivity? What would you do if no alternative is available? (2)
with a history of immediate penicillin hypersensitivity.
Alternatives: If no alternative is available and essential, consider 3rd generation cephalosporins or cefuroxime (2nd generation)
Should cefuroxime (2nd gen) be given with or without food?
Needs to be given with food to maximise absorption as it is POORLY absorbed
Which generations of cephalosporins are less susceptible to inactivation by beta- lactamases?
2nd and 3rd generations
What are examples of glycopeptides?
Vancomycin, Teicoplanin, Telavancin
What is the mechanism of action of glycopeptides? (2)
Binds to cell wall precursor components
Inhibits cell wall synthesis
What bacteria’s are glycopeptides active against? (1)
Aerobic and anaerobic gram+ ve bacteria including MRSA
What are the indications of glycopeptides? (3)
Clostridium difficile infection
Endocarditis
Surgical prophylaxis when high risk of MRSA
What are the side effects of glycopeptides? (9)
Nephrotoxicity
Ototoxicity
Blood disorders
Nausea
Chills
Fever
Rashes
Steven-Johnson syndrome
Flushing of the upper body
Who should we avoid vancomycin in? (2)
The elderly
patients with a history of auditory problems
What should we monitor when administering glycopeptides? (6)
In all glycopeptides, monitor:
blood counts
hepatic function
renal function
urinalysis
plasma levels
auditory function in elderly
Are glycopeptides narrow or broad spectrum?
Narrow spectrum
Are vancomycin and teicoplanin given orally for systemic infections?
No
Why may loading doses be required for vancomycin?
Have a long half- life
What should the pre- dose “trough” level be for vancomycin? How can this change for endocarditis, less sensitive MRSA strains, or complicated S. aureus infections? (2)
10-15mg/mL
15-20mg/L for endocarditis, less sensitive MRSA strains, or complicated S. aureus infections
What are warning signs of glycopeptides? What must patients do if they experience these? (6)
Ototoxicity (hearing loss, vertigo, dizziness, tinnitus)
Red man syndrome (flushing of the upper body)
Blood disorders (fever, sore throat, mouth ulcers, unexplained bleeding or bruising)
Phlebitis (drug irritates tissue causing inflammation)
Nephrotoxicity (elevated serum creatinine levels)
Skin disorders (rashes, pruritic, SJS)
Patient must report all to a doctor immediately
What can happen if glycopeptides are administered too quickly?
Hypotension and anaphylaxis can occur
Can glycopeptides be given in pregnancy? (2)
Manufacturer advices avoiding
If used, it is essential to monitor plasma concentration. This is to minimise foetal toxicity
Can glycopeptides be given when breastfeeding?
It is present in milk but significant absorption is unlikely
What are interactions of vancomycin (glycopeptides)? (3)
NEPHROTOXICITY AND OTOTOXCITY: Ciclosporin, aminoglycosides, polymyxin antifungals
OTOTOXICTY: loop diuretics
ENHANCES effects of suxamethonium
What is the mechanism of action of clindamycin (a lincosamide)? (3)
Bacteriostatic
Binds to ribosomes
Inhibits cell wall protein synthesis
What types of bacteria is clindamycin active against?
Gram +ve aerobes and anaerobes
What are the indications of clindamycin? (4)
Staphylococcal joint and bone infections
Intra-abdominal sepsis
Cellulitis
Skin and soft- tissue infections
What individuals require monitoring when administering clindamycin? (2)
Infants(monitor hepatic and renal function)
those being treated for > 10 days
What are side effects of clindamycin? (7)
GI disturbances
Oesophageal disorders
Taste disturbances
Jaundice
Blood disorders
Rashes
SJS
What should a patient on clindamycin do if they develop diarrhoea? (2)
DISCONTINUE treatment immediately if diarrhoea develops and CONTACT GP
as antibiotic associated colitis can be fatal
Who should we not use clindamycin in?
Patients with existing diarrhoea
What type of individuals is antibiotic-associated colitis more common in? (2)
Middle-aged and elderly women
Especially post-operation
What are examples of macrolides? (3)
erythromycin
azithromycin
clarithromycin
What is the mechanism of action of macrolides? (2)
Bacteriostatic
Binds to ribosomes
Inhibiting cell wall protein synthesis
What antibacterial is a good alternative in penicllin-allergic patients? (2)
Macrolides
have similar activity to penicillin
What are indications of macrolides? (3)
respiratory tract infections e.g. whooping cough, lyme disease
H Pylori
Skin and soft tissue infections
What are side effects of macrolides (4)
Gi disturbances mainly with erythromycin
hepatotoxicity
rash (SJS)
ototoxicity at high doses
What are contraindications of macrolides? (2)
may aggravate myasthenia gravis
use in caution with patients predisposed to QT interval prolongation
i.e electrolyte disturbances & taking drugs that prolong QT interval such as sotalol
What is telithromycin?
A derivate of erythromycin
What are side effects of telithromycin? (4)
May cause visual disturbances
transient loss of consciousness
affect performance of skilled tasks and driving
hepatotoxicity: discontinue treatment and seek medical advice
Are macrolides broad or narrow spectrum?
broad
How should azithromycin be taken? (2)
OD
leave a 2- hour gap before food/indigestion remedies
How should clarithromycin be taken?
BD
What is a side effect of clarithromycin?
taste disturbance
How should erythromycin be taken? (2)
QDS
leave a 2- hour gap before indigestion remedies
What can spiramycin cause?
Toxoplasmosis
Are erythromycin and clarithromycin potent enzyme inhbiitors or inducers?
potent enzyme inhibitors
Why can macrolides interact with warfarin? (2)
potent enzyme inhibitors
increased risk of bleeding
why can macriolides interact with statins?
increased risk of myopathy
What is the mechanism of action of metronidazole? (5)
Bactericidal
a pro- drug
the active form binds to DNA
disrupts its helical structure
inhibiting bacterial DNA synthesis
What types of bacteria does metronidazole have high activity against?
anaerobic bacteria and protozoa
What are the indications of metronidazole? (5)
ALTERNATIVE TO PENICILLIN for many ORAL infections where patients are either ALLERGIC to penicillin or the infection is being caused by PENICILLIN- RESISTANT anaerobes
H. Pylori eradication
Acute oral infections
Leg ulcers
Pressure sores
What are side- effects of metronidazole?(5)
GI disturbances
Taste disturbances
Furred tongue
Oral mucositis
Anorexia
When should we monitor patients on metronidazole?
if treatment exceeds 10 days
How should we take metronidazole? (2)
Take with or just after food
Avoid alcohol whilst taking and for up to 48 hours after. Can cause disulfiram- like reaction with alcohol i.e nausea and vomiting.
Which penicillins are beta- lactamase sensitive? (3)
pen V
Pen G
Amoxicillin
Which penicillin is penicillinase- resistant?
Flucloxacillin
What is the mechanism of action of penicillins? (2)
Prevent peptidoglycan cross- linking
Inhibit bacterial cell wall synthesis
Which bacterias is penicillin active against? (2)
Gram - ve and Gram + ve
What are the indications of penicillins? (5)
Oral infections
Otitis media
Cellulitis
Respiratory tract infections
Pneumonia
What are side effects of penicillins? (6)
Hypersensitivity (1- 10%)
Anaphylaxis (<0.05%)
Maculopapular rash is common with ampicillin and amoxicillin
Diarrhoea
Antibiotic associated colitis
CNS toxicity: rare but serious. Caused by encephalopathy due to cerebral irritation, occurs at high doses or renal impairment
Maculopapular rash is common with which penicillins? (2)
Ampicillin and Amoxicillin