Infection - High Flashcards
What is mepacrine hydrochloride indicated for?
Giardiasis
What is the initial management for suspected sepsis?
Broad-spectrum antibiotic at the maximum dose, ideally within 1 hour
Why is lactate raised in infection?
Increased production due to anaerobic metabolism and insufficient oxygen delivery / Poor clearance
Which antibiotics can be used to prevent recurrence of Rheumatoid fever?
Phenoxymethylpenicillin OR Sulfadiazine
What is used to prevent secondary cases of group A Streptococcal infections?
Phenoxymethylpenicillin
What can be used to prevent secondary cases of group A Streptococcal infections in patients allergic to penicillins?
Erythromycin OR Azithromycin
What is an unlicensed use for dexamethasone?
Bacterial meningitis
What does MRSA stand for, and what kind of organism is it?
Meticillin-resistant Staphylococcus aureas is a gram-positive anaerobic bacteria
What are the first line treatment options for prophylaxis of recurrence of Rheumatic fever (group A strep)?
Phenoxymethylpenicillin
Sulfadiazine
What are the first line options for prophylaxis of recurrence of secondary cases of meningococcal meningitis?
Ciprofloxacin
OR
Rifampicin
OR
Ceftriaxone
What are the first line options for prophylaxis of secondary cases of invasive group A streptococcal infections?
Phenoxymethylpenicillin
Erythromycin or Azithromycin (in penicillin allergy)
What are the first line treatment options for the treatment of septicaemia?
- Tazocin or cephalosproin
- If meticillin-resistant S.aureus suspected add glycopeptide (vanc or teic)
- If anaerobic infection suspected add metronidazole
Which drug class does cefotaxime belong to?
Cephalosporins
What are the first line treatment options for the treatment of meningococcal septicaemia?
- Benzylpenicillin
- Cefotaxime (in pen allergy)
- Chloramphenicol (hypersensitivty to pen and cephalosporins)
What are the first line options for the blind treatment of endocarditis suspected in natural heart valves?
- Amoxicillin (+gentamicin)
- If meticillin-resistant S.aureus suspected use vanc + gent
- In severe gram-negative infection use vancomycin and meropenem
What are the first line options for the blind treatment of prosthetic heart valve endocarditis?
- Vancomycin + rifampicin + low dose gentamicin
What are the first line options for the treatment of natural valve endocarditis caused by staphylococci?
- Flucloxacillin
- Vancomycin + rifampicin (in pen allergy / meticillin resistant S.aureus)
4 weeks
What are the first line options for the treatment of prosthetic valve endocarditis caused by staphylococci?
- Flucloxacillin + gentamicin + rifampicin
- Vancomycin + gentamicin + rifampicin (pen allergy / meticillin resistant S.aureus
2 weeks
What are the first line treatment options for the treatment of endocarditis caused by fully-sensitive streptococci?
- Benzylpenicillin
- Vancomycin + gentamicin (pen allergy)
4 - 6 weeks (stop gent after 2 weeks)
What are the first line options for the treatment of endocarditis caused by less-sensitive streptococci?
- Benzylpenicillin + gentamicin
- Vancomycin + gentamicin (pen allergy / highly pen resistant)
4-6 weeks
What are the first line options available for the treatment of endocarditis caused by enterococci?
- Amoxicillin + gentamcin
- Vancomycin + gentamicin (pen allergy / pen resistant)
4 - 6 weeks
What are the first line options for the treatment of endocarditis caused by HACEK microorganisms?
- Amoxicillin + gentamicin
- Ceftriaxone + gentamicin (pen allergy / pen resistant)
4 - 6 weeks (stop gent after 2 weeks)
What is the first line initial empirical treatment for meningitis?
- Benzylpenicillin before hospital transfer
- In hospital - 3 months - 50 years - cefotaxime or ceftriaxone
- In hospital - >50 years - cefotaxime (or ceftriaxone) + amoxicillin
Consider adjunct use of dexamethasone in hospital
Consider addition of vancomycin if patient has received prolonged course of ABx in last 3 months
What are the first line options for the treatment of meningitis caused by meningococci?
- Benzypenicillin or cephalosporin
- Chloramphenicol if pen/ceph allergic
What are the first line options for the treatment of meningitis caused pneumococci?
- A cephalosporin
- Vancomycin (pen resistant)
What are the first line options for the treatment of meningtitis caused by Haemophilus influenzae?
- A cephalosporin
- Chloramphenicol (pen allergy / resistance)
Consider adjunct dexamethasone
What are the first line options for the treatment of meningitis caused by Listeria?
- Amoxicillin + gentamicin
- Co-trimoxazole (pen allergy / resisitance)
What is the oral first line therapy for the treatment of mild diabetic foot infections?
Flucloxacillin
(erythromycin or doxycycline or clarithromycin in pen allergy)
What are the oral or IV first line options for the treatment of moderate/severe diabetic foot infection?
Flucloxacillin (with or without gentamicin) and/or metronidazole (with or without gentamicin) or co-amoxiclav (with or without gentamicin) or ceftriaxone with metronidazole
Penicillin allergy - Co-trimoxazole (with or without gentamicin) and/or metronidazole
What is the first line treatment option for the treatment of otitis externa if pseudomonas is suspected?
Ciprofloxacin (or an aminoglycoside)
What are the typical first line options for the treatment of otitis externa?
Flucloxacillin
OR
A macrolide (pen allergy)
Which patient group is otitis media commonly seen in?
Children
What are the first line options for the treatment of otitis media in children?
- Amoxicillin
- Co-amoxiclav
What are the first line options for the treatment of otitis media in children with a penicillin allergy?
- Erythromycin or clarithromycin
- Specialist referral
What is the first line option for the treatment of conjunctivitis?
Chloramphenicol eye drops
What is the first line option for the treatment of uncompliacetd acute diverticulitis?
Co-amoxiclav
OR
Cefalexin with metronidazole (pen allergy)
What is the first line option for the treatment of complicated acute diverticulitis?
Co-amoxiclav with metronidazole
OR
Ciprofloxacin with metronidazole (pen allergy)
What are the first line options for the treatment of Salmonella?
Cefotaxime (cephalosporin) or ciprofloxacin (quinolone)
What are the first line options for the treatment of Typhoid fever?
Cefotaxime or ceftriaxone
What are the first line options for the treatment of Shigellosis?
Ciprofloxacin or azithromycin
What is the oral first line treatment for the first episode of C.diff?
Vancomycin
What is the oral second line option for the treatment of C.diff?
Fidaxomicin
What is the oral first line treatment option for a recurrence of C.diff within 12 weeks of the first episode?
Fidaxomicin
What are the first line treatment options for a recurrence of C.diff over 12 weeks since the first episode?
Vancomycin or fidaxomicin
What are the first line options for the treatment of a biliary-tract infection?
ciprofloxacin
OR
gentamicin
OR
a cepahlosporin
What is the first line option for the treatment of bacterial vaginosis?
Metronidazole
What are the first line options for the treatment of uncomplicated genital chlamydial infections?
azithromycin
OR
doxycycline
What are the first line options for the treatment of uncomplicated gonorrhoea?
IM Ceftriaxone
OR
Ciprofloxacin (depending on sensitivity)
What are the first line options for the treatment of osteomyelitis?
- Flucloxacillin
- Clindamycin (pen allergy)
- Vancomycin (if MRSA suspected)
Consider adding fusidic acid or rifampicin for the first 2 weeks in all cases
What are the first line options for the treatment of septic arrthritis?
- Flucloxacillin
- Clindamycin (pen allergy)
- Vancomycin (MRSA suspected)
- A cephalosporin (if gram-negative infection suspected)
What are the first and second line options for the treatment of acute sinusitis?
- Non-life threatening symptoms - phenoxymethylpenicillin
- Lifethreatening symptoms or second line treatment required - Co-amoxiclav
What are the first line options for the treatment of acute sinusitis in a patient with a penicillin allergy?
Doxycycline
OR
Clarithromycin
Oral infections are primarily treated with which groups of antibiotics?
- Broad spectrum penicillins
- Cephalosporins - offer no advantage over penicillins and are often less effective against anaerobes
- Metronidazole - highly effective against anaerobes and is used when penicillins are not suitable
- Tetracyclines and macrolides can both be effective in oral infections and make good alternatives to penicillins, however, neither group is typically used due to growing resisitance
What are the oral first line options for the treatment of an acute exacerbation of bronchiectasis?
amoxicillin
OR
clarithromycin
OR
doxycycline
What are the IV first line options for the treatment of an acute exacerbation of bronchiectasis?
co-amoxiclav
OR
Tazocin
OR
levofloxacin
What is recommended total duration of treatment for an acute exacerbation of COPD?
5 days
What are the oral first line options for the treatment of an acute exacerbation of COPD?
amoxicillin
OR
clarithromycin
OR
doxycycline
What are the second line oral options for the treatment of an acute exacerbation of COPD?
Use of an ABx from a different class from the first used
OR
co-amoxiclav
OR
levofloxacin
OR
co-trimoxazole
What are the first line IV options for the treatment of an acute exacerbation of COPD?
amoxicillin
OR
clarithromycin
OR
co-amoxiclav
OR
co-trimoxazole
OR
Tazocin
What are the choice antibiotics for the treatment of acute cough in pregnancy?
erythromycin or amoxicillin
What is the first line choice for the treatment of acute cough?
doxycycline
What are the first line options for the treatment of low severity CAP?
Amoxicillin
(clarithromycin / doxycycline / erthromycin (pregnancy))
(‘) pen allergy
What are the first line options for the treatment of moderate severity CAP?
Amoxicillin (with clarithromycin or erythromycin (pregnancy))
(clarithromycin or doxycycline in pen allergy)
What are the first line options for the treatment of high severity CAP?
Oral or IV co-amoxiclav with clarithromycin (or erithromycin in pregnancy)
(Levofloxacin in pen allergy)
What are the first line options for the treatment of low severity HAP?
Oral co-amoxiclav
(doxycycline / cefalexin / co-trimoxazole / levofloxacin)
(‘) penicillin allergy or co-amoxiclav unsuitable
What are the first line treatment options for the treatment of high severity HAP?
IV:
Tazocin / ceftazidime with azibactam / ceftriaxone / cefuroxime / levofloxacin / meropenem
If MRSA is suspected or confirmed add glycopeptide such as vancomycin or teicoplanin
What are the two types of impetigo and how do the differ?
Non-bullous - more common / thin walled vesicles and pustules that rupture quickly and form a gold-brown crust
Bullous impetigo - less common / fluid filled vesicles and blisters that rupture and form a yellow-brown crust
What should be offered for the treatment of impetigo before considering antibiotic therapy?
Hydrogen peroxide 1% cream
What is the first line oral antibiotic for the treatment of impetigo?
Flucloxacillin
Clarithromycin or erythromycin in pen allergy
What is the topical first line antibiotic for the treatment of impetigo?
Fusidic acid
What is the macrolide of choice in pregnancy?
Erythromycin
What are the first line options for the treatment of cellulitis and erysipelas?
Flucloxacillin
Clarithromycin, erithromycin or doxycycline in pen allergy
What are the first line options for the treatment of severe cellulitis or erysipelas?
co-amoxiclav / vlinadmycin / cefuroxim / ceftriaxone
What are the first line options for the antibiotic treatment of leg ulcers in non-severely unwell patients?
Flucloxacilin
What is the second line antibactiotic option for the treatment of leg ulcers in non-severely unwell patients?
Co-amoxiclav
What is the first line antibiotic option for the treatment of leg ulcers in severely unwell patients?
Flucloxacillin with or without gentamicin and/or metronidazole
Are antibiotics ever appropriate for the treatment of animal bites and stings?
Yes, but only when there are signs of an infection
What is the first line antibiotic treatment for human and animal bites?
Co-amoxiclav
What is the first line topical option for the treatment of infections secondaru to common skin infections?
Fusidic acid
What is the first line oral option for the treatment of infections secondary to common skin conditions?
Flucloxacillin
Clarithromycin or rythromycin in pen allergy
What is the first line option for the treatment of mastitis during breast feeding?
Flucloxacillin
Does gentamicin have any activity against anaerobic bacteria?
No
Ideally treatment with gentamicin should not exceed how many days?
7 days
How many times a day are aminoglycosides typically administered?
Once
What is used to treat gentamicin-resistant gram-negative bacterial infections?
Amikacin
When should ‘once daily’ dosing of aminoglycosides such as gentamicin be avoided?
- Endocarditis due to gram-negative bacteria
- Endocarditis due to HACEK organisms
- Burns exceding more than 20% of the body
Are carbapenems effective against MRSA?
No
Which antibiotics contain beta-lactam rings?
- Penicillins
- Carbapenems
- Cephalosporins
What is the spectrum of activity of carbapenems?
Broad spectrum against gram-positive and gram-negative, as well as anaerobes
What type of organism is Haemophilus influenzae?
Gram-negative bacteria
Despite being a broad spectrum antibiotic, which type of organism is azithromycin more effective against?
Gram-negative bacteria
What is the MHRA warning associated with the use of erythromycin?
Caution required due to cardiac risks (prolongation of QT interval); drug interaction with rivaroxaban (December 2020)
Which drug class does metronidazole belong to?
Nitroimidazoles
Which indication is Tazocin commonly used for but not actually licensed for?
Acute exacerbation of COPD
What is the generic name of penicillin G
Benzylpenicillin sodium
What is the generic name of penicillin V
Phenoxymethylpenicillin
What are some important safety warnings for the use of quinolones?
- Tendon damage and rupture
- potential for seizures during use - exacerbated by concurrent use with NSAIDs
What are some important safety warnings for the use of tetracyclines?
- Myasthenia gravis (muscle weakness)
- Lupus exacerbation
What is spectrum of activity of fusidic acid
Very narrow - effective against staphylococcal infections
What is the spectrum of activity of linezolid?
Linezolid is effective gram-positive bacteria including MRSA and glycopeptide resistant enterococci
What is the first line option for the treatment of inhalation or gastro-intestinal anthrax?
Ciprofloxacin or doxycycline (in patients >12 years)
Should be used in combination with one or two other antibiotics such as benzylpenicillin, clindamycin, vancomycin, or rifampicin
What is the first line option for the treatment of cutaneous anthrax?
Ciprofloxacin or doxycycline (patients >12 years)
How is multibacillary leprosy treated?
Three drug regimen for at least 2 years:
- rifampicin
- dapsone
- clofazimime
How is paucibillary leprosy treated?
Two drug regimen for at least 6 months:
- rifampicin
- dapsone
What is the first line option for the treatment of Lyme disease in patients presenting with erythema migrans rash or non-focal symptoms?
Doxycycline
What is the first line option for the treatment of Lyme disease in patients presenting with symptoms of central nervous involvement?
IV ceftriaxone
What are the treatment options for lower UTIs caused by MRSA?
doxycycline / trimethoprim / ciprofloxacin / co-trimoxazole
What is the first line treatment option for complicated UTIs caused by MRSA?
Glycopeptide such as vancomycin
What are the phases of treatment for tuberculosis?
Initial phase
Continuation phase
What drug treatments are used in the initial phase of tuberculosis treatment and how long should they be used for?
- Rifampicin
- Pyrazinamide
- Ethambutol hydrochloride
- Isoniazid (with pyridoxime hydrochloride)
2 months
What drug treatments are used during the continuous phase of tuberculosis treatment and how long should they be used for?
- Rifampicin
- Isoniazid (with pyridoxine hydrochloride)
4 months
How does treatment vary from standard regimes for the treatment of central nervous system tuberculosis?
- Initial phase for 2 months
- Continuous phase for 10 months
- Initial high dose of dexamethasone or prednisolone to be offered at the same time and reduced over 4 - 8 weeks
How does treatment vary from standard regimes for the treatment of pericardial tuberculosis?
- Initial high dose of dexamethasone or prednisolone to be offered at the same time and reduced over 2 - 3 weeks
What are the first line options for the treatment of lower UTI in non-pregnant women?
Nitrofurantoin or trimethoprim
What are the second line options for the treatment of lower UTI in non-pregnant women?
- Nitrofurantoin (if not tried first line)
- Fosfomycin
- Amoxicillin
What are the first line options for the treatment of lower UTI in men?
Nitrofurantoin or trimethoprim
What is the first line option for the treatment of lower UTI in pregnant women?
Nitrofurantoin
What is the second line option for the treatment of lower UTI in pregnant women?
Amoxicillin or cefalexin
What is the first line option for the treatment of acute prostatitis?
Ciprofloxacin
What are the oral first line options for the treatment of acute pyelonephritis in non-pregnant women and men?
Ciprofloxacin
OR
Cefalexin
What is the oral first line option for the treatment of recurrent UTI?
Nitrofurantoin or trimethoprim
What is the oral second line option for the treatment of recurrent UTI?
Amoxicillin or cefalexin
What are the first line options for the treatment of catheter-associated UTI in non-pregnant women and men?
Nitrofurantoin, trimethoprim or amoxicillin
What is the first line option for the treatment of catheter-associated UTI in pregnant women?
Cefalexin
What are the three main types of fungal infections?
- Aspergillosis
- Candidiasis
- Cryptococcis
What are the four most commonly prescribed types of antifungals?
- Triazole antifungals
- Imidazole antifungals
- Polyene antifungals
- Echinocandin antifungals
What type of antifungal is fluconazole?
Triazole
What type of antifungal is clotrimazole?
Imidazole
What type of antifungal is ketoconazole?
Imidazole
What type of antifungal is nystatin?
Polyene
What type of antifungal is caspofungin?
Echinocandin
Which type of antifungal is associated with the prevention of systemic fungal infections
Triazole (fluconazole)
Which type of antifungal is associated with the treatment of local infections such as vaginal candidiasis?
Imidazole (clotrimazole)
Which antifungal is commonly used for the treatment of oral, oropharyngeal, and perioral fungal infections?
Nystatin
Polyene antifungal
Which type of antifungal is only effective against aspergillus spp and candida spp?
Echinocandins (caspofungin)
What is the drug of choice for the treatment of threadworms and ascarides (roundworms)
Mebendazole
Which two drugs are the choice treatment for tapeworm (taenicides and hydatid infections) infections?
Niclosamide and albendazole
What is the alternative when mebendazole cannot be used for the treatment of ascaricides?
Levamisole
Which treatments are effective against hookworms?
Mebendazole, albendazole, levamisole
How long before travelling should chloroquine be taken for the prophylaxis of malaria?
1 week
How long should prophylactic medicine be taken after leaving a malaria high risk area?
4 weeks
When is the use of chloroquine unsuitable for malaria prophylaxis and what are the alternatives?
Chloroquine and mefloquine are unsuitable in patients with epilepsy
Doxycyline or atovaquone with proguanil are the alternatives
What is the drug of choice for the treatment of P.falciparum malaria?
Artemether with lumefantrine
What is the first line choice for the treatment of P.falciparum malaria when artemether treatment is unavailable?
Quinine with doxycycline
What is the MHRA warning associated with the use of chloroquine?
Increased risk of cardiovascular events when used with macrolide antibiotics (February 2022)
Can aciclovir be used for the treatment of genital herpes?
No
Which antivirals can be used for the treatment of genital herpes?
Famiciclovir
Valaciclovir
Can famiciclovir be used for the treatment of herpes simplex?
No
What are the types of herpesvirus infections?
Herpes simplex
Varicella-zoster
Chickenpox and shingles are caused by which organism?
Varcella-zoster
What is the backbone regimen of choice for the treatment of HIV?
- Emtricitabine
- Tenofovir alafenamide or tenofovir disoproxil
What are the options for a third drug to be used in addition to the backbone regimen for the treatment of HIV?
Atazanavir or Darunavir - both boosted with ritonavir
What should the initial treatment regimen for HIV consist of?
- 2x nuceloside reverse transcriptase inhibitors (NRTIs)
+ - Intergrase inhibitor (INI) / non-nucleoside reverse transcriptase inhibitor (NNRTI) / boosted protease inhibitor (PI)
Protease inhibitors are boosted with ritonavir
Within how long of symptom onset should oseltamivir be started for the treatment of influenza?
48 hours
What are some potential side effects associated with the use of oseltamivir?
- Herpes simplex infection
- Dizziness
- GI upset
- sleep disorders
- Vertigo
To which drug class does gentamicin belong to?
Aminoglycosides
To which drug class does amikacin belong to?
Aminoglycosides
To which drug class does neomycin belong to?
Aminoglycosides
Which aminoglycoside is typically used topically?
Neomycin
Which aminoglycosides are typically used systemically?
Gentamicin and amikacin
Aminoglycosides are typically indicated for the treatment of which kinds of bacteria?
Gram-negative aerobes
What are the clinical indications for the use of aminoglycoside antibiotics?
- Treatment of severe sepsis (inclusing those where the source is unidentified)
- Pyelonephritis and complicated urinary tract infections
- Biliary and intraabdominal sepsis
- Endocarditis
- Bacterial skin, eye, or external ear infections
What should aminoglycoside antibiotics be paired with when the cause of an infection is unknown?
Penicillin and/or metronidazole
Do aminoglycosides have any activity against anaerobes?
No
What MHRA warning is associated with the use of all aminoglycosides?
Increased risk of deafness in patients with mitochondrial mutations (January 2021)
What MHRA warning is associated with the use of gentamicin?
Potential of histamine-related adverse reactions with some batches (November 2017)
What are the most important adverse effects associated with the use of aminoglycosides?
- Nephrotoxicity
- Ototoxicity
Ototoxicity may be irreversible and usually not noticed until treatment of acute infection is finished
How are aminoglycosisdes excreted?
Renally
In which condition is the use of all aminoglycosides contraindicated?
Myasthenia gravis
Ototoxicity is more likely when aminoglycosides are co-prescribed with which other drugs?
- Loop diuretics
- Vancomycin
Nephrotoxicity is more likely when aminoglycosides are co-prescribed with which other drugs?
- Ciclosporin
- Cephalosporins
- Platinum chemotherapies
- Vancomycin
Can aminoglycosides be given orally?
No, they are highly polarised and therefore cannot cross the lipid membranes of the gut
How should amoniglycosides be administered?
They should be diluted in NaCl 0.9% solution and infused slowly as to not expose the ears to high bolus concentrations that may lead to to ototoxicity
- Symptomatically - C-reactive protein levels
- Safety - Reanl function measured before and during treatment
- Serum drug concentrations - the next dose should only be given if this concentration is within safe levels
During aminoglycosides therapy, if the pre-dose (trough) serum drug concentration is too high what action must be taken in both adults and children?
The interval between doses must be increased
When should serum drug levels be measured in patients receiving gentamicin therapy?
Pre-dose and 1 hour after administration
In a ‘multiple daily dose’ regimen of gentamicin what should the pre- and post-dose serum concentrations levels ideally be in both adults and children?
Pre-dose (trough) = 5 -10mg/L
Post-dose = <2mg/L
In a ‘multiple daily dose’ regimen of gentamicin specifically for the treatment of endocarditis what should the pre- and post-dose serum concentrations levels ideally be in both adults and children?
Pre-dose (trough) = 3 - 5mg/L
Post-dose = <1mg/L
To which rug class does tobramycin belong to?
Aminoglycosides
What is the basic mechanism of action of the aminoglycosides and which microbes are they effective against
Aminoglycosides bind irreversible to bacterial ribosomes and inhibit protein synthesis.They enterbacterial cells through oxygen-dependent transport systems whichstreptococci and anaerobic bacteria lack, making them ineffective in the treatment of these organisms.
Aminoglycosides are effective against Gram-negative anaerobic bacteria.
Name some antifungal medications
- Clotrimazole
- Fluconazole
- Nystatin
What are the clinical indications for the use of antifungal agents?
- Treatment of local fungal infections (oropharynx, vagina, and skin) orally or topically
- Treatment of invasive or disseminated fungal infections
What is the basic mechanism of action of the antifungal agents?
Fungal cell membranes contain ergostrel, which is not found on animal or human cells, and it is this that is the target for the antifungals. Imidazole and triazole antifungals prevent the synthesis of ergostrel, which in turn inhibits cell membrane synthesis, while polyene antifungals bind to ergostrel and allow ions to leak through the cell membrane.
What are the the 3 main types of antifungal agents?
- Imidazole (clotrimazole)
- Polyene (nystatin)
- Triazole (fluconazole)
What are the adverse effects associated with the use of topical antifungals such as clotrimazole and nystatin?
There are very few except for occasional local irritation
What are the most common adverse effects associated with the use of systemic antifungals such as fluconazole?
- GI upset
- Headache
- Hepatitis
- Hypersensitivity skin reactions
What severe adverse effets are associated with the use of systemic antifungal agents such as fluconazole?
- QT interval prolongation which can lead to arrythmias
- Severe hepatic toxicity
- Hypersensitivity reactions such as anaphylaxis and severe cutaneous reactions
Can fluconazole be used in pregnancy and breastfeeding?
It should be avoided in pregnancy but can be used during breastfeeding
When should caution be advised with the use of fluconazole?
In patients with hepatic impairment due to the increased risk of hepatic toxicity
Dose adjustments are required in patients with moderate renal impairment
Fluconazole interacts with which drugs and to what extent?
- Drugs that are metabolised by P450 enzymes such as carbemazepine, phenytoin, warfarin, diazepam, simvastatin, and sulphonlyureas
- Reduces the antiplatelet effect of clopidogrel which is metabolised in the liver
- Increases the risk of arrythmias when used in combination with drugs that potentially prolong the QT interval such as amiodarone, antipsychotics, quinine, quinolones, macrolides, and SSRIs
How should oral nystatin be administered?
It should be taken after food and held in the mouth to allow for good contact with lesions - dentures must be removed before use
What is a typical topical dose of nystatin for the treatment of thrush?
100,000 units QD for 7 days
What is a typical short course dose of fluconazole?
150mg OD
50mg OD for prolonged (2 weeks) courses
How long after symptoms after resolved should treatment be continued for topical antifungals?
1 - 2 weeks after symptoms have resolved
What should be monitored in prolonged courses of fluconazole?
- Liver enzymes
- Symptoms of liver dysfunction
Which type of drugs increase the risk of oral thrush?
Inhaled corticosteroids
When used in addition to antibiotic and antimuscarinics this risk is increased further
What are the common clinical indications for the use of antivirals such as aciclovir?
- Treatment of acute episodes of herpesvirus infections
- Suppression of recurrent herpes simplex attacks (where they are occurring 6 or more times a year)
What is the basic mechanism of action of aciclovir?
Aciclovir inhibits herpes-specific DNA polymerase which stops any further viral DNA synthesis
What are the potentail adverse effects of associated with the use of aciclovir?
- GI upset
- Headache
- Dizziness
- Skin rash
- Acute renal failure (IV administration only)
When is aciclovir contraindicated?
Aciclovir has no major contraindications
Can aciclovir be used in pregnancy and breastfeeding?
Aciclovir does cross into the placenta and is expressed in breastmilk so caution is advised or its use during pregnancy and breastfeeding
The potential harm caused by viral conditions with which aciclovir is used to treat often outweight the risks of using aciclovir itself in pregnancy and breastfeeding
When is a dose adjustment of aciclovir required?
In severe renal impairment
Which drugs interact with aciclovir?
Aciclovir has no clinically important drug interactions
Name some of the viral conditions in which the use of aciclovir is indicated
- Oral herpes
- Genital herpes
- Herpes simplex encephalitis
- Varicellar-zoster (chickenpox and shingles)
What should be monitored during the use of aciclovir?
- Symptomatic efficacy
- Renal function
What are the clinical indications of cephalosporins and carbapenems?
- Oral cephalosporins are second- and third-line options for the treatment of urinary and respiratory tract infections
- Parenteral cephalosporins and cerbapenems are reserved for severe infections and complicated infections caused by antibiotic resistance
What spectrum of action to cephalosporins and carbapenems have?
Broad spectrum
What kind of bacteria do cephalosporins have increasing activity against?
Gram-negative bacteria
What is the basic mechanism of action of cephalosporins and carbapenems?
Cephalosporins and carbapenems inhibit the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls using their beta-lactam rings. This causes a weakened cell wall, lysis and bacterial cell death
Name the most commonly prescribed cephalosporins
- Cefalexin
- Ceftriaxone
Name the most commonly prescribed carbapenems
- Meropenem
- Ertapenem
What are the important adverse effects related to the use of cephalosporins and carbapenems?
- GI upset
- Increased risk of c.diff
- Antibiotic collitis
- Hypersensitivity reactions
- Increased risk of neurological toxicity leading to seizures
Neurological toxicity is is a risk particularly where carbapenems are being used in high doses in patients with renal impairment
Which group of antibiotics do cephalosporins and carbapenems share allergic cross-sensitivity?
Penicillins
When is the use of cephalosporins and carbapenems contraindicated?
History of allergy to penicillin - particularly if it was a serious reaction such as anaphylaxis
When should carbapenems be used with caution?
R- Patients with epilepsy
- Patients at risk of c.diff
- renal impairment
When should cephalosporins be used with caution?
- Patients at risk of c.diff
- Renal impairment
Which drugs do cephalosporins and carbapenems interact with?
- Warfarin - Increases the anticoagulant effect by killing gut flora that synthesises vitamin K
- Aminoglycosides - Increases the nephrotoxicity of aminoglycosides (Cephalosporins
- Valproate - Reduces the plasma concentration and efficacy of valproate (carbapenems)
How are carbapenems administered?
Intravenously
When are IV cephalosporins used?
In severe infections
How often is ertapenem administered?
Once daily
What drug class does ertapenem belong to?
Carbapenems
How is treatment with cephalosporins and carbapenems monitored?
Symptomatically and using blood test markers such as c-reactive protein
Why is the use of second- and third-generation cephalosporins particularly restricted in most hospital trusts?
Because of the frequency of which antibiotic-associated collitis occurs with the use of these medications
What are the clinical indications for the use of chloramphenicol?
- Bacterial conjuctivitis using eye drops
- Otitis externa using ear drops
Why is oral chloramphenicol rarely used?
It is highly toxic to bone marrow when used systemically
What spectrum of activity does chloramphenicol have?
Chloramphenicol has a broad spectrim of activity and is effective against gram-positive and gram-negative bacteria, as well as aerobes and anaerobes
What is the basic mechanism of action of chloramphenicol?
Chloramphenicol binds to bacterial ribosomes inhibiting protein synthesis. It is therefore bacteriostatic meaning that it simply prevents the growth of bacteria
AT high enough doses it can be bactericidal
What are the most common adverse effects of chloramphenicol use when applied topically?
- Stinging
- Burning
- Itching
When is a dose adjustment of systemic chloramphenicol required?
In patients with hepatic impairment
Where is chloramphenicol metabolised?
Liver
When is the use of chloramphenicol contraindicated?
- In patients with personal or family history of bone marrow disorders
- In patients with previous hypersensitivity reactions
- Third trimester of pregnancy
- Breastfeeding
- Children <2 years of age
What significant interactions does chloramphenicol have with other drugs?
Chloramphenicol has no significant interactions with other medications when used topically
How often should chloramphenicol 0.5% eye drops be applied?
Every 2 hours, then reduced to QD when infection comes under control
How often should chloramphenicol (5-10%) ear drops be applied?
4 drops, 2 - 3 times daily for 7 days
How often should chloramphenicol (1%) eye ointment be applied?
3 - 4 times daily
Can chloramphenicol eye drops be used in the ear, and can chloramphenicol ear drops be used in the eye?
Chloramphenicol eye drops can safely be used in the ear, though they will be less effective than ear drops. Chloramphenicol ear drops cannot be used in the eyes.
What advice regarding contact lenses needs to be given to patients using chloramphenicol eye drops?
Eye drops can become damaged by the preservatives in the eye drops, causing transient blurred vision. All contact lenses should be avoided in eye infection.
Which group of antibiotics end in the suffic ‘mycin’
Macrolides
List the macrolides
- Erythtomycin
- Clarithromycin
- Azithromycin
What are the clinical indications for the use of macrolides?
- Treatment of respiratory, skin and soft tissue infections as an alternative to penicllin when its use is contraindicated
- Severe pneumonia in addition to a penicillin to cover atypical organisms such as Legionella pneumophilia and Mycoplasma pneumoniae
- Elimination of Helicobacter pylori in combination with a PPI and either amoxicillin or metronidazole
What spectrum of antibacterial activity do the macrolides possess?
Erythromycin possess a broad spectrum of activity against gram-negative and gram-positive bacteria.
Newer synthetic macrolides (clarithromycin and azithromycin) have increased activity against gram-negative bacteria, particularly Haemophilus influenzae.
What is the basic mechanism of action of macrolide antibiotics?
Macrolides inhibit bacterial protein synthesis by binding to the 50S subunit of the bacterial ribosome and blocking translocation. They are therefore bacteriostatic as they do not actually kill the bacteria.
Why is resistance to macrolides common?
Due to mutations in the bacterial ribosome
Which macrolide has an increased adverse effects profile?
Erythromycin
What are the important adverse effects associated with the use of all macrolides?
- Macrolides are irriatants and cause GI upset such as nausea, vomiting, diarrhoea, and abdominal pain when given orally, and when thrombophlebitis when given intravenously
- Antibiotic-associated colitis
- Cholestatic jaundice
- Prolongation of the QT interval
- Ototoxicity
When is dose adjustment required for the administration of macrolides?
Macrolides are excreted hepatically with a small renal component, and as such need dose reducing in severe hepatic and renal impairment
Which drugs interact with macrolides and to what extent?
- Warfarin - enhances their anticoagulant effect increasing the risk of bleeding
- Statins - increased risk of myopathy
- Amiodarone - risk of QT prolongation
- Antipsychotics - risk of QT prolongation
- Quinines - risk of QT prolongation
- Quinolones - risk of QT prolongation
- SSRIs - risk of QT prolongation
How are each of the macrolides dosed?
Erythromycin - 250 - 500mg 6 hourly
Clarithromycin 250 - 500mg 12 hourly
Azithromycin 250 - 500mg daily
The frequency of dosing is dictated by how heavily each is concentrated in the tissues
How must macrolides be administered intravenously?
They must be diluted in a large volume of NaCl 0.9% and infused over at least 60 minutes. They cannot be given as IM injections or as bolus IV.
In LRTIs when should macrolides be added and why?
Macrolides should only be added in LRTIs when there is evidence of pneumonia, as macrolides provide atypical cover of Legionella pneumophila and Mycoplasma pneumoniae which cause pneumonia but nother LRTIs such as COPD exacerbations.
What is the spectrum of activity for metronidazole?
Anaerobic bacteria and protozoa
What are the clinical indications for the use of metronidazole?
- Antibiotic-associated colitis caused C.diff
- Oral infections or aspiration pneumonia caused by gram-negative anaerobes
- Surgical and gynaecological infections caused by gram-negative anaerobes
- Protozoal infections
What type of organism is C.diff?
Gram-positive anaerobic bacteria
What is the basic mechanism of action of metronidazole?
Metronidazole is reduced by anaerobic bacteria generating a free radical which binds to bacteria DNA causing widespread degradation and cell death
Aerobic bacteric cannot reduce metronidazole in this manner
What are the main adverse effects associated with the use of metronidazole?
- GI upset
- Hypersensitivity reactions
- Neurological effects such as: seizures, peripheral and optical neuropathy, and encephalopathy (mainly when used at high doses for prolonged duration)
- Sensitivity to sunlight when used topically
How is metronidazole metabolised?
Metronidazole is metabolised by hepatic cytochrome P450 enzymes
What should be avoided during metronidazole treatment?
Alcohol should not be consumed during treatment with metronidazole
Metronidazole inhibits the enzyme responsible for clearing the immediate metabolic product of alcohol, and concurrent use of the two causes disuliram-like reactions such as flushing, headache, vomiting
Is metronidazole an inducer or an inhibitor?
Inhibitor of cytochrome P450
What are some important interactions between metronidazole and other drugs/classes?
- Warfarin - increased risk of bleeding
- Phenytoin - increased risk of otoxicity / reduced efficacy of metronidazole
- Rifampicin - reduced efficacy of metronidazole
What is a typical oral dose and frequency of oral metronidazole?
400mg every 8 hours
What is a typical IV dose and frequency of IV metronidazole?
500mg every 8 hours
IV metronidazole is reserved for severe infections of where patients are nil by mouth
Which antibiotics interact with alcohol?
- Metronidazole (disulfarim-like reaction)
- Co-trimoxazole (dislfarim-like reaction - rare)
- Doxycycline (delays effectiveness)
- Erythromycin (delays effectiveness)
What needs to be monitored during treatment with metronidazole?
- Symptoms
- Inflammatory markers (CRP)
- In a course exceeding 10 days - FBC and LFTs
What is the MHRA warning associated with the use of nitrofurantoin?
Reminder of the risk of pulmonary and hepatic adverse drug reactions (April 2023)
What are the clinical indications for the use of nitrofurantoin?
- Treatment of uncomplicated lower urinary tract infection
- Prophylaxis of recurrent UTI
What are some alternatives to nitrofurantoin for the treatment of uncomplicated UTI?
- Trimethoprim
- Amoxicillin
- Cefalexin
What is the spectrum of activity of nitrofurantoin?
Nitrofurantoin has a broad spectrum of activity against most UTI causing organisms
E.coli (Gram-negative) and S.saprophyticu (Gram-positive)
What is the basic mechanism of action of nitrofurantoin?
The primary metabolite when nitrofurantoin is reduced by bacteria damages bacterial DNA and causes cell death
What are some important adverse effects associated with the use of nitrofurantoin?
- GI upset
- Hypersensitivity reactions
- Discolouration of urine to dark yellow or brown
- Chromic pulmonary reactions
- Hepatitis
- Peripheral neuropathy
When is the use of nitrofurantoin contraindicated?
- In pregnant women approaching term
- In babies in their first 3 months of life
- Renal impairment
What interactions are there between nitrofurantoin and other drugs/classes?
There are no significant interactions between nitrofurantoin and other commonly prescribed drugs
What is the typical duration of treatment with nitrofurantoin for women with an uncomplicated lower UTI infection?
3 days is usually sufficient
When is a 7 day or longer course of nitrofurantoin required?
- UTIs in men
- More complicated lower UTIs
What are the key points when counselling a patient on the use of nitrofurantoin?
- May colour urine dark yellow or brown, this is harmless
- Notify Dr if they experience symptoms of peripheral neuropathy or pulmonary reactions such as pins and needles or breathlessness respectively
What are the common clinical indications for the penicillins benzylpenicillin and phenoxymethylpenicillin?
- Streptococal infection, including tonsilitis, pneumonia (with a macrolide or tetracycline), endocarditis (with gentamicin) and skin and soft tissue infections (with flucloxacillin)
- Meningococcal infection
- Clostridial infection
What is the spectrum of activity of benzylpenicillin and phenoxymethylpenicillin?
Narrow - activity against some gram-positive and gram-negative organisms
What is the basic mechanism of action of the penicillins benzylpenicillin and phenoxymethylpenicillin?
Using their beta-lactam rings they inhibit the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls; this creates an osmotic imbalance (draws in water) that causes cell lysis and death
What are some important adverses effects associated with the use of penicillins?
- Allergic reactions inclusing skin reactions or anaphylaxis
- Neurological toxicity (when used at very high doses or due to renal impairment)
When is the use of penicillins contraindicated?
In peniciliin allergy
What are the important interactions between penicillins and other drugs/classes?
Penicillins reduce the renal excretion of methotrexate increasing the risk of toxicity
How is benzylpenicllin administered?
It can only be administered via IV or IM injection as it cannot be absorbed by the GI tract
Which antibiotic should be used to treat sore throat or a young person caused by an unknown organism and why?
Phenoxymethylpenicillin should be used as opposed to amoxicillin. This is because amoxicillin commonly causes rash if the causative agent is Epstein-Barr virus
What is the most commonly prescribed antipseudomonal penicillin?
Piperacillin with tazobactam (Tazocin)
What are the common indications for the use of Tazocin?
- LRTIs
- UTIs
- Intraabdominal sepsis
- Skin and soft tissue infections
What is the spectrum of activity of Tazocin?
Broad range of activity against gram-positive, gram-negative, and anaerobic organisms
What are the important adverse effects associated with the use of Tazocin?
- GI upset
- Antibiotic colitis
- Increased risk of C.diff (all broad spectrum antibiotics)
- Hypersensitivity reactions
When should antipseudomonal antibiotics be used with caution?
- In patients with C.diff
- Dose adjusted in patients with moderate/severe renal impairment
Which drugs/classes interact with Tazocin and to what effect?
- All penicillin reduce the renal excretion of methotrexate and therefore increase the risk of toxicity
- As a broad spectrum Abx, Tazocin enhances the effect of warfarin by killing GI flora that synthesise vitamin K
How long is a typical course of Tazocin?
5 - 14 days
4.5g every 4 - 6 hours
What needs to be taken into account when considering electrolyte replacement for a patient being treated with Tazocin?
Each dose of Tazocin contains 11mmol of Na and is often infused in NaCl 0.9%
What are the most commonly prescribed broad-spectrum penicillins?
Co-amoxiclav
Amoxicillin
What are the common clinical indications for the use of the broad spectrum penicillins?
- Amoxicllin is used to treat a variety of infections such as CAP, otitis media, sinusitis, and UTIs
- Helicobacter pylori-associated infections (amoxicillin used with clarithromycin or metronidazole and a PPI)
- Co-amoxiclav is used for the treatment of severe hospital-acquired infections)
What is the spectrum of activity of amoxicillin?
Broad spectrum
What is the spectrum of activity of co-amoxiclav?
Broad spectrum
What are the important potential adverse effects associated with the use of broad-spctrum penicillins?
- GI upset
- Increased risk of C.diff
- Antibiotic-associated colitis
- Allergic reactions
What is an adverse effect associated with the use of co-amoxiclav but not amoxicillin?
Acute liver injury (generally self-limiting)
When should broad-spectrum penicillins be used with caution?
- Patients with C.diff
- Patients with a history of acute liver injury
- Dose adjustments required in severe renal impairment
With drugs do the broad-spectrum penicillins interact with?
- Warfarin - broad spectrum antibiotics kill the GI flora that synthesise vitamin K
What are the benefits of prompt IV-to-oral switching of antibiotics?
Reduces the adverse effect risk profile and cost of treatment
What is the most commonly prescribed penicillinase-resistant penicillin?
Flucloxacillin
What are the common clinical indications for the use of penicillinase-resistant penicillins?
Straphylococcal infection, usually as part of a combination therapy, including:
1. Skin and soft tissue infections
2. Osteomyelitis and septic arthritis
3. Other infections including endocarditis
How does flucloxacillin differ from other penicillins?
It has a acyl side chain that protects its beta-lactam ring making it effective against beta-lactamase-producing staphylococci
Which organism resists the activity of flucloxacillin by reducing its binding activity?
MRSA
What are some important adverse effects associated with the use of flucloxacillin?
- GI upset
- Allergic reactions
- Liver toxicity
When is the use of flucloxacillin contraindicated?
- Penicillin allergy
- History of flucloxacillin-related hepaticotoxicity
Which drugs interact with flucloxacillin and to what extent?
Flucloxacillin reduces the renal excretion of methotrexate and increases the risk of toxicity
What are the common clinical indications for quinine sulfate?
- Leg cramps (depending on the severity of the case)
- Treatment of Plasmodium falciparum malaria
What is the basic mechanism of action of quinine sulfate?
It reduces the excitability of the motor end plate in response to acetylcholine, helping to reduce leg cramps
The exact mechanism of action in the treatment of malaria is unknown outside of the fact it kills the malaria parasites
What are some important adverse effects associated with the use of quinine?
- GI upset
- Tinnitus, deafness, blindness
- Prolongation of the QT interval
- Potentially fatal overdose
When should be quinine be used with caution?
- Patients with a history of sight or hearing loss
- It is teratogenic and should be avoided in the first trimester of pregnancy but the ebenefits may outweigh the risks
- It should be avoided in patients with G6PD deficiency
Which drugs interact with quinine?
Drugs that prolong the QT interval:
- Quinolones
- Macrolides
- SSRIs
- Amiodarone
- Antipsychotics
What is quinine sulfate commonly given alongside for the treatment of malaria?
Doxycycline
At what dose and for how long is a trial of treatment of nocturnal leg cramps with quinine sulfate?
200 - 300mg ON for 4 weeks
If after 4 weeks there is no benefit then treatment should be stopped
If trial treatment of nocturnal leg cramps is successful when should quinine treatment be reviewed and potentially stopped?
After 3 months of treatment
Which group of drugs uses the suffix ‘floxacin’?
Quinolones
What are the most commonly prescribed quinolones?
Ciprofloxacin
Moxifloxacin
Levofloxacin
What are the common clinical indications for the use of the quinolones?
Quinolines are reserved as second- and third-line treatments of:
- UTIs (mostly gram-negative)
- Severe gastroenteritis
- LRTIs (gram-positive and gram-negative)
What is the spectrum of activity of quinolones?
Broad spectrum of activity with particular activity against gram-negative bacteria
Newer quinolones such as moxifloxacin and levofloxacin have enhanced activity against which spectrum of bacteria?
Gram-positive
How is ciprofloxain unusual as an oral antibiotic?
It has particular activity against Pseudomonas aeruginosa
What is the basic mechanism of action of the quinolone antibiotics?
They kill bacteria by inhibiting bacterial DNA synthesis
Which groups of antibiotics are most comonly associated with C.difficile colitis?
Cephalosporins
Quinolones
What are the common adverse effects associated with the use of quinolone antibiotics?
- GI upset
- Hypersensitivity reactions
- Lowering of the seizure threshold
- Inflammation and rupture of tendons
- Prolongation of QT interval
- Increased risk of C.diff
What are the MHRA warnings associated with the use of quinolone antibiotics?
- Systemic and inhaled fluoropuinolones: small increased risk aortic aneurysm and dissection (November 2018)
- Fluoroquinolone antibiotics: new restrictions and precautions for use due to very rare reports of disabling and potentially long-lasting or irreversible side effects (March 2019)
- Systemic and inhaled fluoroquinolones: small risk of heart valve regurgitation; consider other therapeutic options first in patients at risk (December 2020)
When should quinolones be used with caution?
- History of seizures
- Children and growing young people
- Those with other risk factors for QT prolongation
Which drugs interact with quinolones and to what extent?
- Drugs containing divalent cations (calcium and antacids) reduce the efficacy of quinolones
- Theophylline - increased risk of theophylline toxicity
- Co-prescription with NSAIDs increases the risk of seizures
- Co-prescription with prednisolone increases the risk of tendon rupture
Do quinolones extend the QT interval?
Yes
When should quinolones be prescribed with caution?
In co-prescription with other drugs that prolong the QT interval:
- Amiodarone
- Antipsychotics
- Macrolides
- Quinine
- SSRIs
Which antibiotic has good activity against organisms that cause traveller’s diarrhoea?
Ciprofloxacin
What are the most commonly precribed tetracycline antibiotics?
Doxycyline
Lymecycline
What are the common clinical indications for the use of tetracycline antibiotics?
- Acne vulgaris
- LRTIs including infective exacerbations of COPD and pneumonia
- Chlamydial infections
- Other infectiosn such as typhoid, malaria, lyme disease, and anthrax
What is the spectrum of activity of tetracyclines?
Broad
Use is limited however due to increasing resistance
What is the basic mechanims of action of tetracycline antibiotics?
Tetracyclines inhibit bacterial protein synthesis and are therefore bacteriostatic
Of the broad spectrum antibiotics, which class has a lower risk of causing C.diff infections?
Tetracyclines
What are the important adverse effects associated with the use of tetracyclines?
- GI upset
- Oesophageal irritation, ulceration and dysphagia
- Photosensitivity
- Discolouration of teeth in children
- Hepatotoxicity
- Intracranial hypertension
Can tetracyclines be used during pregnancy and breastfeeding?
No, they bind to teeth and bones during fetal development, infancy and early childhood
When should tertracyclines, particularly doxycyline be used with caution?
- Alcohol dependence
- Renal impairment
Which drugs interact with tetracyclines and to what extent?
- Divalent cations and so there should be a 2 hour gap betwen administration of tetracyclines and calcium or antacids
- Warfarin - increased anticoagulant effect as tetracyclines kill GI flora that synthesise vitamin K
What is a typical regimen for treatment using doxycyline?
200mg OD on day 1,then 100-200mg OD for 4-6 days
What are the key points when counselling a patient on the use of tetracyclines?
- Should be taken with a meal
- Protect their skin from the sun
- Avoid indigestion remedies
What are some other, non-antibiotic, properties of tetracyclines that are being explored?
- Anti-inflammatory
- Immune-modulation
- Neuroprotective effects
Trimethoprim is the first line treatment for what indications?
- Acute lower UTIs
- Prophylaxis of recurrent UTI
What is the spectrum of activity of trimethoprim?
Broad against gram-positive and gram-negative bacteria though it is becoming limited due to resistance - hence the addition of sulfonamide in co-trimaxazole
What is the basic mechanism of action of trimethoprim?
Trimethoprim inhibits the synthesis of bacterial folate. It is therefore bacteriostatic.
What are the important adverse effects associated with the use of trimethoprim?
- GI upset
- Skin rash
- Hypersensitivity reactions
- Haematological disorders such as thrombocytopenia, megaloblastic anaemia, and leucopenia (due to its action as a folate antagonist)
- Hyperkalaemia
Can trimethoprim be used in pregnancy and breastfeeding?
It should be avoided in the first trimester of pregnancy due toits teratogenic effects
It is not known to be harmful in breastfeeding
When should trimethoprim be used with caution?
- People with folate deficiency
- Renal impairment
- Neonates and the elderly
- HIV infection
Which drugs interact with trimethoprim and to what extent?
- Potasium elevating drugs such as aldosterone antagonists, ACE inhibitors, and ARBs
- Other folate antagonists such as methotrexate
- Drugs that increase folate metabolism such as phenytoin
- Warfarin - increased anticoagulant effect
Why is trimethoprim less effective in patients with renal impairment?
As trimethoprim inhibits creatinine secretion by the renal tubules leading to small and reversible increase in serum creatinine concentrations. Serum creatinine and trimethoprim then compete to be excreted into the urinary tract, the site of action of trimethoprim
What is a typical dose of trimethoprim for the treatment of UTI?
200mg BD
What is a typical dose of trimethoprim for prolonged prophylaxis of recurrent UTI?
100mg OD
Which drug class does vancomycin belong to?
Glycopeptides
What are the common clinical indications for the use of vancomycin?
- Treatment of gram-positive infections (e.g. endocarditis) where the infection is severe or penicillins cannot be used
- Treatment of antibiotic-associated colitis cause dby C.difficile (second line where metronidazole is ineffective or poorly tolerated)
What is the spectrum of activity of vancomycin?
Narrow - effective against only gram-positive bacteria, notably MRSA and C.diff
What is the basic mechanims of action of vancomycin?
Vancomycin inhibits the growth and cross-linking of peptidoglycan chains, inhibiting the synthesis of the cell wall of gram-positive bacteria, making it bactericidal
What are the important adverse effects associated with the use of vancomycin?
- Thrombophlebitis
- Allergic reactions
- ‘Red man syndrome’
- Nephrotoxicity (IV)
- Ototoxcity (IV)
- Neutropenia (IV)
- Thrombocytopenia (IV)
When should vancomycin be used with caution?
- Renal impairment
- Elderly
Which drugs interact with vancomycin and to what extent?
Vancomycin increases the risk of ototoxicity and/or nephrotoxicity when prescribed with:
- Aminoglycosides
- Loop diuretics
- Ciclosporin
How is vancomycin given for the treatment of C.diff infections
Orally as it acts topically in the GI system - 125mg 6-hrly for 10-14 days
What is the target serum concentration range when using IV vancomycin?
Between 10 - 15mg/L
What should be monitored in prolonged courses of vancomycin?
- Plasma drug concentrations
- Renal function
- Platelets
- Leukocytes
- WCC
- CRP
Which drug class does teicoplanin belong to?
Glycopeptides
What is the cautionary label for flucloxacillin 500mg?
Take on an empty stomach
Chloramphenicol eye drops can be sold over the counter for children of what age?
2+