antibacterials Flashcards
BEFORE STARTING THERAPY, The follow must be considered?
Viral infections should not be treated with
antibacterials
• Samples should be taken for culture and
sensitivity testing
• Narrow-spectrum antibacterial are preferred
Dose varies
Route of administration varies
Duration varies
The dose varies according to factors including?
age, weight, hepatic function, renal function, and severity of infection
Route of administration of an antibacterial often depends on t
the severity of the infection, usually IV for life-threatening
Duration of therapy depends on?
the nature of the infection and the response to treatment, undue prolonged courses encourage resistance, may lead to side-effects and are costly
General antibacterials suitable for pregnancy?
Penicillin and cephalosporins, Nitrofurantoin may also be used but it should be avoided at term
2 classes of antibiotics that should be avoided in pregnancy?
Diaminopyrimidines and quinolones
should also preferably be avoided particularly in the first trimester?
Trimethoprim
Antibacterials normally excreted by the kidney accumulate with resultant toxicity unless the dose is reduced; especially?
Antibacterials normally excreted by the kidney accumulate with resultant toxicity unless the dose is reduced; especially?
List down the 5 aminoglycosides ?
Amikacin, Gentamicin, Neomycin, Streptomycin, Tobramycin
Mechanism of action of aminoglycosides?
Bactericidal by irreversibly binding to ribosomes inhibiting protein synthesis; fissure result which enhances antibiotic uptake as well as leakage of cell contents.
Aminoglycosides are active against?
Active against some gram +ve bust mostly gram -ve
7 main Indication of aminoglycosides?
Endocarditis, septicaemia, meningitis and other CNS infections, biliary-tract infection, prostitis, and pneumonia.
3 aminoglycosides active against P. aeruginosa?
Amikacin, tobramycin and gentamicin
Aminoglycoside active against M. tuberculosis?
streptomycin
8 main Side-effects of aminoglycosides?
May impair neuromuscular transmission, irreversible ototoxicity, nephrotoxicity. Nausea, vomiting, antibiotic associated colitis, peripheral neuropathy, electrolyte disturbances.
Contraindications and cautions?aminoglycosides
Caution in patients with clinical muscular weakness e.g. myasthenia gravis;
avoid concomitant use with ototoxic drugs e.g. cisplatin and furosemide, and nephrotoxic drugs e.g. vancomycin and ciclosporin
Route of administration for aminoglycosides?
Aminoglycosides are not absorbed from the gut and therefore are given parenterally for systemic infections
Which aminoglycoside can be given orally for bowel sterilisation prior to surgery or in hepatic failure
Neomycin
Dosing of aminoglycosides?
Once daily doses preferred over multiple daily doses, need to consult local guidelines.
is the aminoglycoside of choice in the UK.
Gentamicin, has a narrow therapeutic index
Therapy with gentamicin requires x with dosing?
Loading dose,
narrow therapeutic Range for gentamicin?
multiple daily dose regimens one-hour (peak) serum concentration should be 5 to 10mg/L (3 to 5 mg/L for endocarditis);
pre-dose (trough) concentration should be < 2mg/L (< 1mg/L for endocarditis);
Monitoring for all aminoglycosides?
Renal function (nephrotoxicity); auditory and vestibular function (ototoxicity which is irreversible);
serum-aminoglycoside concentration must be determined in?
the elderly, all patients receiving parenteral treatment, those with renal impairment, in obesity and cystic fibrosis, and if high doses given.
Warning sign of gentamicin toxicity?
Nephrotoxicity
• Ototoxicity (hearing impairment or hearing disturbance)
• Dehydration (ensure patient is well hydrated before treatment to prevent dehydration)
Caution for Pregnancy and breastfeeding using gentamicin ?
Risk of auditory or vestibular nerve damage in 2nd and 3 rd trimester, avoid unless essential
Gentamicin Drug Interactions?
Increased risk of nephrotoxicity when given with ciclosporin, tacrolimus, vancomycin • Increased risk of ototoxicity when given with loop diuretics, vancomycin
List down CEPHALOSPORINS?
Five generations of this antibiotic group exist:
- Cefalexin, cefradine
- Cefaclor, Cefuroxime
- Cefixime, Ceftriaxone
- Ceftaoline fosamil
Mechanism of action of cephalosporins?
Prevent cell wall synthesis by binding to enzymes called penicillin binding proteins (PBPs).
Cephalosporins are bactericidal to?
both gram -ve and gram -ve activity
Indications of cephalosporins?
Pneumonia, meningitis, gonorrhoea, and UTIs
Cephalosporins side-effects?
Antibiotic associated colitis (rare but more common with 2nd and 3rd generation)
Cephalosporins Contraindications and cautions?
Hypersensitivity (0.5-6% of penicillin-sensitive patients will also be allergic to cephalosporins
less susceptible to inactivation by beta-lactamases?
2nd and 3rd gen are less susceptible
List down glycopeptides?
Vancomycin, Teicoplanin, Telavancin
Glycopeptides mechanism of action ?
Inhibit cell wall synthesis by binding to the cell wall precursor components, this leads to interference of the PBP enzymes preventing cell wall synthesis
Glycopeptides Are Active against?
aerobic and anaerobic gram +ve bacteria including MRSA
Glycopeptides indication?
Clostridium difficile infection, endocarditis, surgical prophylaxis when high risk of MRSA
Glycopeptides side effects?
Nephrotoxicity, blood disorders, ototoxicity, nausea, chills, fever, rashes, SJS (Steven-Johnson syndrome), flushing of the upper body
Glycopeptides Contraindications and cautions?
Avoid vancomycin in elderly, and in patients with a history of auditory problems
Glycopeptides Monitoring?
Differs between glycopeptides: blood counts, hepatic and renal function, urinalysis, plasma levels, auditory function in elderly
Vancomycin doing may require? Why?
Loading doses may be required due to long half-life;
Vancomycin therapeutic range?
trough 10 to 15mg/L (15 to 20mg/L for endocarditis or less sensitive strains of methicillin-resistant Staphylococcus aureus or complicated infections caused by S. aureus)
Monitoring (all glycopeptides)
blood counts, hepatic and renal function, urinalysis, plasma levels, auditory function in elderly
Vancomycin in pregnancy and breast feeding?
Manufacturer advises to avoid – if used plasma concentration monitoring essential to minimise foetal toxicity; present in milk, significant absorption unlikely
Drug Interactions with vancomycin?
ciclosporin, aminoglycosides, polymixin antifungals- Increased risk of nephrotoxicity and ototoxicity
loop diuretics- ncreased risk of ototoxicity
Vancomycin enhances effects of suxamethonium
What drug is a lincosamides??
Clindamycin
Mechanism of action of clindamycin?
Binds to ribosomes inhibiting cell wall protein synthesis
Clindamycin bacteriostatic action against ?
gram +ve aerobes and anaerobes
Clindamycin indication?
Staphylococcal joint and bone infections, intra abdominal sepsis, cellulitis, skin and soft-tissue infections
Clindamycin monitoring?
Hepatic and renal function in infants, and in all patients where treatment exceeds 10 days
Clindamycin side effects
GI disturbances, oesophageal disorders, taste disturbances, jaundice, blood disorders, rash, and SJS
discontinue treatment immediately if clindamycin causes
if diarrhoea develops , Antibiotic associated colitis can be fatal
Clindamycin contraindication and caution
Do not use in patients with existing diarrhoea; antibiotic associated colitis is more common in middle-aged and elderly women, especially post operation.
List down macrolides
Erythromycin, azithromycin, clarithromycin
MACROLIDES MOA?
Binds to ribosomes inhibiting cell wall protein synthesis; similar activity to penicillin thus are an alternative in allergic patients
MACROLIDES, indication?
Respiratory tract infections e.g. pertussis (whooping cough; Lyme disease
MACROLIDES, side effects?
GI disturbances mainly with erythromycin; hepatotoxicity, rash (SJS)
MACROLIDES Contraindications and cautions?
May aggravate myasthenia gravis; use in caution with patients predisposed to QT interval prolongation (i.e. electrolyte disturbances and taking drugs the prolong QT interval e.g. sotalol)
