Infection Flashcards
What types of antibiotics are safest to use in pregnancy?
Penicillins and cephalosporins
Which antibiotics should be avoided in pregnancy?
Trimethoprim (folate antagonist - teratogenic)
Quinolones
Diaminopyrimidines (eg trimethoprim)
Tetracycline (dental discolouration)
Which is NOT a notifiable disease?
- TB
- Measles
- Food poisoning
- Endocarditis
- Meningitis
Endocarditis
The rest should be notified by drs to the Proper Officer of local authority
Name the aminoglycosides
Gentamicin, amikacin, neomycin, streptomycin, tobramycin
What is the mode of action of aminoglycosides?
Irreversibly bind to ribosomes and inhibit protein synthesis
‘Aminoglycosides have mainly got gram +ve action’
True or false
False - they are active against some gram +ve organisms and many gram -ve
Which condition are aminoglycosides contra-indicated in?
Myasthenia gravis - impair neuromuscular transmission
Which aminoglycoside is NOT given IV?
Neomycin
Rest must be IV as not absorbed by gut
Monitoring for aminoglycosides?
- Renal function - can be nephrotoxic especially in renal impairment
- Auditory function - can cause irreversible ototoxicity
- Serum concentrations esp in elderly/pregnant patients
‘When dosing aminoglycosides for obese patients ideal body weight should ALWAYS be used’
True or false?
True
‘Gentamicin is inactive against anaerobes’
True or false?
True, has good gram -ve activity
When should gentamicin levels be taken in multiple-daily dosing?
- At peak concentration (1 hour post-dose) and levels should be 5-10mg/L
- At trough conc (pre-dose) and levels should be <2mg/L
What are key warning signs for patients taking gentamicin?
- Dehydration
- Ototoxicity
- Nephrotoxicity
Name some antibiotics associated with ototoxicity?
- Aminoglycosides (inc gentamicin)
- Glycopeptides (inc teicoplanin + vancomycin)
How many generations of cephalosporins are there?
5 generations 1st - eg cefalexin 2nd - eg cefuroxime 3rd - eg cefotaxime 4th - eg cefepime 5th - eg ceftobiprole
Some indications for cephalosporins?
UTI, gonorrhoea, pneumonia, meningitis
What is the main side effect of cephalosporins?
Hypersensitivity
0.5-6% of patients with penicillin will also be allergic
c/i in patients with IMMEDIATE HYPERSENSITIVITY to penicillin
How are cephalosporins excreted?
Renally
Reduce doses in renal imp.
Which cephalosporin is poorly absorbed and must be taken with food?
Cefuroxime
‘Carbapenems are narrow spec antibiotics’
True or false?
False - they are broad spectrum
Active against gram +ve, gram -ve and anaerobes
Some indications for carbapenems?
Severe hospital-acquired infections
Complicated UTIs
Why is ertapenem cautioned in epilepsy?
Has seizure-inducing potential and can cause CNS disorders
‘Carbapenems are renally excreted’
True or false?
True
Name some glycopeptides?
Vancomycin, teicoplanin, telavancin
Some indications for glycopeptides?
MRSA, C diff, endocarditis, surgical prophylaxis if high risk of MRSA
Which is NOT a side effect of glycopeptides?
- Steven Johnsons syndrome
- Blood disorders
- Flushing
- Hypertension
- Ototoxicity
HTN
Name contra-indications for glycopeptides?
- Elderly
- History of auditory problems
Which antibiotic is associated with red man syndrome?
Vancomycin
signs - flushing of upper body, angioedema, hypotension
How is serum conc of vancomycin measured?
Trough level on second day of treatment
Should be 10-15mg/L
- also monitor renal + hepatic function, auditory func and blood counts
What are some warning signs for patients on Vancomycin?
- ototoxicity (inc vertigo, dizziness + tinnitus, avoid with other drugs causing this eg loop diuretics, aminoglycosides)
- flushing
- blood disorders (inc sore throat, mouth ulcers, unexplained bleeding)
- nephrotoxicity
- skin disorders
- anaphylaxis + hypotension (if administered too quickly)
What is the minimum rate for a 500g dose of vancomycin?
Not exceed 10mg/min
Which antibiotic should be discontinued IMMEDIATELY if diarrhoea develops?
Clindamycin
Risk of fatal antibiotic-associated colitis
Also C/I in existing diarrhoea
‘Clindamyin is well concentrated in bones and excreted in bile + urine’
True or false
True
Indicated in staphylococcal bone + joint infections
What patient counselling is required for clindamycin?
- Take capsule with a full glass of water
- report any diarrhoea immediately
Why is clindamycin cautioned in middle aged/elderly women?
- colitis can be more common
- especially following surgery
‘Macrolides have a similar action to penicillins’
True or false?
True - and similar spectrum
Often an alternative in penicillin allergy
Which macrolide is most likely to cause GI disturbances?
Erythromycin
Some indications of macrolides?
Respiratory tract infections, chlamydia, skin infections
When are macrolides cautioned?
Conditions that pre-dispose QT prolongation eg, electrolyte disturbances, other drug with risk of QT prolongation
Azithromycin may be sold OTC, for what indications and under what conditions?
Sold for confirmed + asymptomatic chlamydia infection
Single dose of 1g
Over 16 years
Which enzyme do macrolides inhibit?
CYP3A4
Esp clarithromycin + erythromycin
Some drugs that interact with clarithromycin + erythromycin?
- statins - risk of rhabdomylosis
- corticosteroids - risk of cushings syndrome
- CCBs - risk of hypotension/QT prolongation
- carbamazepine
- warfarin - increased anticoagulation
- PPIs - increased gastric pH
- Benzodiazepines - excess CNS depression
Which type of bacteria does metronidazole have a high activity against?
Anaerobic
Some indications of metronidazole?
- anaerobic infections
- oral infections
- leg ulcers
- pressure sores
- H pylori
Which antibiotic is the preferred treatment for tetanus?
Metronidazole
Why is metronidazole not recommended in breast feeding?
Can give milk a bitter taste
Patient counselling for metronidazole?
- Do not drink alcohol
- Take with food
Which antibiotics MUST be taken with food?
- Metronidazole
- Doxycycline
- Cefuroxime
- Nitrofurantoin
What route should metronidazole be given by?
Orally
Well absorbed orally, IV reserved for severe infections
Also effective rectally/vaginally
How do penicillins work?
Inhibit bacterial cell wall synthesis by preventing peptidoglycan cross-linking
Caution for penicillin treatment?
History of allergy
1 - 10% people have allergic reactions following exposure
<0.05% patients have anaphylaxis
Which patients are at risk of immediate hypersensitivity to penicillins?
- patients with atopic allergy eg, asthma, eczema, hay fever
- patients with a history of rash/hives/anaphylaxis IMMEDIATELY after penicillin administration
Which other antibiotics should be avoided in patients with a history of penicillin hypersensitivity?
Cephalosporins
Other beta-lactams
Some indications for penicillins?
Oral infections, cellulitis, otitis media, respiratory tract infections, pneumonia, meningitis
Some side effects of penicillins?
Maculopapular rash, antibiotic-associated colitis, diarrhoea (esp broad spec), CNS toxicity (in high doses/renal imp)
Does metronidazole require a dose reduction in renal impairment?
No
What risk is associated with clavulanic acid (eg in co-amoxiclav)?
Risk of cholestatic jaundice
- more common in men or patients >65
- rare in children
- jaundice usually self-limiting
- max treatment 14 days
Safety warning associated with flucloxacillin?
Risk of hepatic disorders - cholestatic jaundice and hepatitis
- Can occur rarely up to 2/12 after fluclox stopped
- Higher risk with increased age or treatment over 2 weeks
- Do not use if history of hepatic dysfunction or impairment
Name some quinolone antibiotics?
Ciprofloxacin, levofloxacin, moxifloxacin, ofloxacin, norfloxacin
‘Ciprofloxacin is commonly used to treat MRSA’
True or false?
FALSE
Many staphylococci are resistant to quinolones and should be avoided in MRSA infection
Two safety warnings associated with quinolones?
- risk of convulsions
- risk of tendon damage
Why should quinolones not be taken at the same time as NSAIDs?
Can induce convulsions
What are some risk factors for tendon damage meaning quinolones should be used with caution?
- age >60
- use of corticosteroids
- history of tendon disorders
Why should quinolones be avoided in children?
Risk of arthropathy (joint disease) seen in animals
Cautions for use of quinolones?
- conditions with risk of seizures
- QT prolongation (risk factors include HF, MI, bradycardia, electrolyte imbalance)
- Photosensitivity (avoid sunlight exposure)
- diabetes (can affect blood glucose)
Side effects of quinolones?
GI disturbance, headache/dizziness, QT prolongation, skin reactions, depression/suicidal tendencies (discontinue drug if any psychiatric/neurological reactions occur)
Patient counselling for quinolones?
- may impair performance of skilled tasks eg driving
- should be taken on an empty stomach (cipro + levo)
- do not take with indigestion remedies, iron or zinc (or milk with cipro)
Name a contra-indication for Trimethoprim?
Blood dyscrasias
Cautioned in the elderly as higher risk of blood disorders
On long term therapy monitor blood counts
Which patient counselling is required for trimethoprim/co-trimoxazole?
Risk of blood disorders - report any signs eg, sore throat, rash, bruising, bleeding
Why should trimethoprim/co-trimoxazole be avoided in pregnancy?
Folate antagonist - can be teratogenic especially in the first trimester
Can trimethoprim be used in renal impairment?
No - reduce dose <30 and avoid <15
Which tetracycline has the broadest spectrum?
Minocycline
But all are broad spec antibiotics
Some indications of tetracyclines?
Chlamydia, rickettsia, acne, rosacea, respiratory infections
Why are tetracyclines contra-indicated in children under 12?
Can bind to calcium in bones and teeth and cause discolouration
Also cannot be used in pregnancy/breast feeding
Which tetracycline should be taken with food?
Doxycycline
Why would you be concerned if a patient taking tetracycline complained of a headached and vision changes?
Risk of intracranial hypertension
Which antibiotics should be avoided in myasthenia gravis?
- Aminoglycosides (eg gentamicin, cause impaired neuromuscular transmission)
- Tetracyclines (can increase muscle weakness)
What counselling should be given to patients who are prescribed tetracyclines?
- Risk of photosensitivity, avoid excess sunlight exposure
- Taking with antacids, and some elements such as Ca, Zn, Fe can decrease absorbtion
- Should be swallowed whole with plenty of fluid while sitting/standing upright to avoid irritation of the jaw and throat
Which tetracyclines should NOT be taken with milk?
oxytetracycline, tetracycline, demeclocycline
How is doxycycline used for malaria prevention?
- 100mg OD
- Take 1-2 days before entering endemic area and continue for 4 weeks after leaving
What is in co-trimoxazole?
Trimethoprim + sulfamethoxazole
Which antibiotics should be taken on an empty stomach?
- Azithromycin caps
- Phenoxymethylpenicillin (pen v)
- Flucloxacillin
- Tetracycline
Which antibiotic requires plasma creatinine kinase to be measured as there is a risk of myopathy?
Daptomycin
Why is chloramphenicol reserved for ‘life threatening’ infections in systemic use?
Associated with serious haematological side effects
Why should chloramphenicol be avoided in pregnancy and breast feeding?
Risk of grey baby syndrome
‘Linezolid has a role in treating MRSA + VRE’
True or false?
True
Only active against gram +ve bacteria
Which monitoring is required with linezolid?
- weekly FBC - risk of haematpoeitic disorders
- signs of visual impairment - risk of optic neuropathy
Which foods should be avoided with linezolid?
MAOI - avoid foods rich in tyramine
eg, bovril, marmite, mature cheese, salami etc
Why is linezolid cautioned in the elderly?
High risk of blood disorders
Why is linezolid cautioned in uncontrolled hypertension?
Can cause hypertension
How do you treat TB?
Initial phase (2 months): Rifampicin, Isoniazid, Pyrazinamide + Ethambutol
Continuous phase (4 months): Rifampicin and isoniazid
Can you give TB treatment to a pregnant/breast feeding patient?
Yes
Side effects of TB drugs?
Rifampicin - liver toxicity, discolouration of bodily fluids
Isoniazid - liver toxicity, peripheral neuropathy
Pyrazinamide - liver toxicity
Ethambutol - ocular toxicity
What is pyridoxine and why must it be given with isoniazid?
Vitamin B6
For prophylaxis of peripheral neuropathy
Where does the antibacterial Nitrofurantoin act?
Bacteriacidal in the renal tissue and through the urinary tract
What colour can nitrofurantoin turn urine?
Yellow/brown
What is the renal dosing for nitrofurantoin?
Avoid if eGFR <45ml/min
Why is nitrofurantoin cautioned in hepatic imp?
Risk of cholestatic jaundice + hepatitis
What is amphotericin B?
A polyene antifungal used for severe/systemic fungal infections
Why should a test dose be given before administering amphotericin B?
Toxicity and anaphylaxis is common
Give test dose and observe patient for 30 mins
Some acute ADRs may need prophylactic antipyretics or hydrocortisone
Under which conditions can fluconazole be sold to the public?
For treatment for vaginal candidiasis and associated candidal balanitis (penile thrush)
Age 16-60
Single dose of 150mg
Name some triazole antifungals?
Fluconazole, itraconazole, posaconazole
What safety warning is associated with itraconazole?
Risk of heart failure
- do not give to patients at high risk of HF including: older adults, pts with cardiac disease, chronic lung disease, history of HF or negatively inotropic drugs
Rare risk of life-threatening hepatotoxicity
- monitor LFTs in prolonged treatment
- patients should seek medical advice if signs of hepatotoxicity appear inc dark urine, jaundice, abdo pain, N+V
Why should patients taking voriconazole be issued with an alert card?
1. Risk of hepatotoxicity seek immediate medical attention if signs of liver dysfunction 2. Phototoxicity Avoid excess sun exposure seek medical attention for sunburn monitor for signs of malignancy on skin
What are the signs of threadworm?
- Itching around anus/vagina
- weight loss
- sleep disturbance
How should threadworm be treated?
Mebendazole 100mg single dose
- with good hygiene measures
- licensed for age 2+ OTC, should treat whole household
- if reinfection is suspected a second dose may be taken after 2 weeks
What should be recommended for bite protection for travellers at risk of malaria?
- Wear longs after dusk
- Use mosquito nets with permethrin
- Use DEET 20-50%
What advice should be given to travellers using DEET at the same time as sunscreen?
DEET reduces SPF
Apply DEET after sunscreen
How is malaria prophylaxis given?
Before entering endemic area: - usually start 1 week prior - doxycycline + malarone 1-2 days prior - mefloquine 2-3 weeks prior After leaving endemic area: - Usually continue for 4 weeks - Malarone continued for one week
What is in Malarone?
Atovaquone + proguanil
Which anti-malarials should not be used in epilepsy?
Mefloquine + chloroquine - risk of neuropsychiatric reactions
Which anti-malarials should be used in pregnancy?
Proguanil with folic acid supplements
AVOID malarone
Which antimalarial has a risk of ocular toxicity?
Chloroquine
low risk at doses below 4mg/kg
What is the major side effect associated with mefloquine?
Neuropsychiatric reactions
- C/I in history of psychiatric disorders including depression
- Common: abnormal dreams, insomnia, depression, anxiety
- Long half life so effects may continue for months following discontinuation
- psychiatric symptoms can be a sign or more serious events, discontinue treatment
What is quinine used for?
Treatment of malaria and nocturnal leg cramps
Why is quinine cautioned in cardiac disease?
Risk of QT prolongation
