Infections Flashcards
What is used in guiding selection of antibiotic
Kirby-Bauer method
What is used to determine lowest conc. of antibiotic that inhibits visible bacterial growth vs conc. that kills >99.9% bacteria
Dilution test
How do antibiotics that inhibit cell wall synthesis act?
- Inhibits synthesis of peptidoglycan
- bind irreversibly to penicillin binding protein
- leads to cell death
What class of antibiotics don’t need b-lactamase inhibitors
- Monobactams
- Carbapenem
General side effects of b-lactactame antibiotics
Nausea and diarrhoea
Examples of b-lactamase inhibitors
Tazobactam
Clavulanic acid
What class of drugs interfere with bacteria cell wall
‘PCCM’
- penicillin
- cephalosporins
- carbapenems
- monobactams
Side effects of fosfomycin
Nausea
Diarrhoea
Dizziness
Headache
Side effects of cycloserine
Neurological and psychological disturbances
Side effects of vancomycin
- Hypotension
- Flushing (red man syndrome)
- Nephrotoxicity
- Ototoxicity
- Blood disorders
What drugs are used in tuberculosis
Isaniazid
Ethambutol
Side effects of isoniazid
Hepatotoxicity
Peripheral neuropathy
(tingling, constipation, numbness, diarrhoea)
Side effects of ethambutol
Vision loss
What drugs are CI in penicillin allergy
Cephalosporins
Which cephalosporins are excreted by the liver
Ceftriaxone
Cefoperadone
the rest are excreted by the kidney
What drug interferes with the absorption of penicillin and cephalosporins
Probenecid - used in gout and gouty arthritis
Side effects of cephalosporins
- hypersensitivity
- GI distress - C.Diff & Diarrhoea
- Rare haemolytic anaemia
- Severe bleeding
What is used as an alternative to cephalosporin
- gram +: Monobactams
- gram -: Macrolides
What cephalosporins have disulfiram like action
Cefoperazone
Cefotitan
intolerance to alcohol
Examples of first gen cephalosporins
’cefa’
- Cefazolin
- Cefalexin
- Cefradine
Examples of second gen cephalosporins
- Cefaclor
- Cefuroxime
- Cefotetan
Examples of third gen cephalosporins
’ime, one, ten, ir except cefuroxime’
-Ceftriaxone
- Cefotaxime
- Cefixime
Does the third gen cephalosporins cross BBB
Yes
and cefuroxime
What cephalosporin can be used for surgical prophylaxis
Cefazoline
long half life
What cephalosporin can be used in meningitis
Cefuroxime
crosses BBB
What cephalosporins are used in resistant infection
Cefuroxime
Cefoxitin
Symptoms of infection
- Fever, aches and pains
- Pus, swelling or inflammation
- Drowsiness in children
- Confusion in elderly
- Worsening renal function
Clinical markers of infection
- Low blood pressure
- Raised blood glucose (hyperglycaemia)
- High ESR, C-receptive protein, temperature, respiratory rate, pulse
What are the cell membrane integrity disruptors
Daptomycin
Polymyxins
Side effect of daptomycin
Skeletal muscle toxicity
Side effect of polymyxins
Nephrotoxicity
Neurotoxicity
What type of bacteria do cell wall synthesis inhibitors work on?
Rapidly dividing bacteria
Which penicillin is resistant to b-lactamase
Flucloxacillin
Route of administration of Pen G and why
Benzylpenicillin
IV / IM
They are destroyed by gastric acid when given orally
What infection are Pen G and Pen V used to treat
Syphilis - T.pallidum
Jaw infections
the ‘cocci’ infections
- Streptococci (Depot)
- Pneumococci
- Meningococci
What type of penicillin are amoxicillin and ampicillin
Broad spectrum b-lactam sensitive
Between amoxicillin and ampicillin, which has the least GI side effects
Amoxicillin
Does amoxicillin have a food interaction?
No
ampicillin does
What is the main use of amoxicillin in infections
Lungs: COPD, pneumonia, bronchiectasis
When is ampicillin used
Listeria (meningitis)
When are PipTaz used? (Extended spectrum penicillin)
UTIs
Burns
HAP
How are penicillins excreted?
Exception?
Renally
Except; Nafcillin & Oxacillin which is excreted by the liver
What penicillin drugs are excreted by the liver?
Naficillin
Oxacillin
Side effects of penicillin
- Hypersensitivity reaction
- GI distress
- Jarisck herxheimer (siphylis)
When shouldn’t Broad spectrum penicillin (amoxicillin and ampicillin) be given
Blindly for sore throat - glandular fever (causes rash that can be mistaken for hypersensitivity)
How should ampicillin be taken
Before food
Main side effect of amoxicillin
Cholestatic jaundice- do not exceed 14 days
Main side effect of Flucloxacillin
Cholestatic jaundice
Hepatitis
How should Flucloxacillin be taken
Before food
What type of infections are vancomycin used to treat
MRSA
Enterococci
Also C. diff
Trough target for vancomycin
10-15 mg/ml
15-20 mg/ml in endocarditis
Drugs that target nucleic acid synthesis
- Metronidazole
- Quinolones
- Rifampicin
Use of metronidazole
Dental infections
Vaginal trichomoniasis
Side effects of metronidazole
- Taste disturbances
- Furred tongue
- Oral mucositis
- GI disturbance
Counselling for metronidazole
Avoid alcohol
Take with it after food
What to do if peak level is high?
Reduce dose
Maintain interval
What to do if trough is high but peak is okay
Maintain dose
Increase interval
When should patient report illness after visiting a malaria region
Within 1 year
Especially within 3 months of return
What is used to treat externa otitis
- Flucloxacillin
- Clarithromycin/ azithromycin/ erythromycin - Pen allergy
- Ciprofloxacin/ aminoglycoside
A woman is one week away from giving birth and has contracted UTI. What is the best treatment and why?
Cefalexin
Trimethoprim - teratogenic
Nitrofurantoin - Avoid at term
What age is tetracycline CI
< 12 years
What age should quinolones be avoided
< 18 years
Cause disease of the joint - arthropathy
What class of antibiotics should be avoided in renal impairment
- Aminoglycosides (gentamicin, amikacin,etc)
- Glycopeptides (vancomycin)
- Tetracyclines
- Nitrofurantoin
Nephrotoxicity
What antibiotics should be avoided in Hepatotoxicity
- Tetracycline
- Rifampicin
What antibiotics cause cholestatic jaundice
Amoxicillin
Flucloxacillin
What antibiotics are contraindicated in pregnancy
‘Carrying **M*others Cannot Take Antibiotics’
- Clarithromycin
- Metronidazole
- Chloramphenicol (grey-baby syndrome)
- Tetracycline (affects skeletal development, risk of discolouration of child’s teeth - 2nd/3rd trimester)
- Aminoglycosides (auditory or vestibular nerve damage - 2nd/3rd trimester)
General antibiotic cautionary and advisory label
Space the doses evenly throughout the day
Keep taking this medicine until the course is finished, unless you are told to stop.
Antibiotics associated with C.diff (antibiotics associated colitis) and thrush (Candida) eg. Vaginal thrush
- Clindamycin
- Broad spec penicillin (amoxicillin & ampicillin)
What is used to treat infections caused by staphylococcus
Flucloxacillin
What is used to treat infections caused by MRSA
Vancomycin
Linezolid
What is used to treat infections caused by streptococcus
Benzylpenicillin (Pen G)
Phenoxymethylpenicillin (Pen V)
What is used to treat infections caused by anaerobic bacteria
Metronidazole
What is used to treat infections caused by pseudomonas aeruginosa
Gentamicin
What is the causative agent of Community Acquired Pneumonia (CAP)
Staphylococcus - Flucloxacillin
What is the causative agent of impetigo or cellulitis (skin)
Staphylococcus - Flucloxacillin
Warning sign of C.diff and what to do
Diarrhoea
STOP antibiotic and see a GP
When is linezolide used?
As an alternative to vancomycin in MRSA infection
Side effect of linezolid
- Blood disorders (STOP if bone marrow suppression)
- Optic neuropathy especially when used over 28 days. (Report visual symptoms)
Linezolid interaction with food
Tyramine (cheese, soya beans)
Linezolid drug interactions
Antidepressants
SSRIs, TCAs or MAOi
Wash out period of linezolid
2 weeks
Trimethoprim dose
200mg BD
Side effect of trimethoprim
Blood dyscrasias: long term use
Hyperkalaemia
When is co-trimoxazole used
- pneumocystis jirovecii pneumonia
- Leg ulcer - pen allergy
- diabetic foot infection
Side effects of co-trimoxazol
- Rashes
- SJS
- Photosensitivity
- Blood dyscrasia (long term use)
- Hyperkalaemia
Side effects of chloramphenicol
- Blood dyscrasias
- Grey baby syndrome (avoid in pregnancy)
What type of bacteria is metronidazole active against
Anaerobic bacteria
Bacterial vaginosis
Side effects of metronidazole
- Furred tongue
- Dark urine
- Taste disturbances
- Liver enzyme increase
- Nausea/ vomiting
- GI disturbances (take with or after food)
Nature of interaction: Metronidazole and alcohol
Disulfriam-like reaction
Avoid alcohol during the course for at least 48 hours after
How is metronidazole taken?
With or after food
Avoid alcohol
Side effect of nitrofurantoin
- Blood dyscrasias
- Acute pulmonary reactions
- Cholestatic jaundice
- Peripheral neuropathy
When should nitrofurantoin be avoided?
- Renal impairment eGFR <45
- Infants < 3 months old
- Acute porphyria
How is nitrofurantoin taken?
With or after food
Nitrofurantoin and urine
Yellow / brown
Nitrofurantoin dose
IM tx: 50mg QDS
IM Prophylaxis: 50-100mg ON
MR Tx: 100mg BD
Examples of aminoglycosides
Gentamicin
Tobramycin (via inhaler in cystic fibrosis)
Amikacin (gentamicin resistant gram - bacilli)
Streptomycin (tuberculosis)
How are aminoglycosides given?
Parenteral route
Not absorbed by the gut
How is gentamicin used in blind therapy?
With metronidazole and/or penicillin
When to avoid OD gentamicin
- Renal impairment <20ml/min
- HACEK or gram(+) endocarditis
- Burns cover > 20% of body
When to monitor gentamicin
After 3 or 4 doses
After dose change
Target plasma levels of gentamicin
Peak: 5-10mg/ml (3-5mg/ml for endocarditis)
Trough: <2mg/ml (<1mg/ml)
sample taken 1 hour after dose
What do you do to gentamicin dose in renal impairment
Increase intervals
Severe: reduce dose
Side effects of gentamicin
Nephrotoxicity
Ototoxicity (report hearing loss, tinnitus, or vertigo)
Drugs that increase risk of nephrotoxicity with gentamicin
- Ciclosporin
- Tacrolimus
- Vancomycin
Aminoglycosides in pregnancy
Avoid
Auditory and vestibular damage in 2nd and 3rd trimester
risk small with gentamicin
Duration of treatment with aminoglycosides
7 days
Aminoglycosides with loop diuretics counselling
Ototoxicity
Separate by long period as possible
When is gentamicin contraindicated
Myasthenia gravis - muscle weakness
Electrolyte imbalance of aminoglycosides
HypO K, Ca and Mg
MHRA warning with gentamicin
Histamine related adverse drug reactions
Examples of glycoproteins
- Vancomycin
- Teicoplanin
- Telavacin (only in HAP when other antibiotics are unsuitable)
How are glycoprotein given
Parenteral rout
Not by mouth in systemic infections
When is vancomycin used?
- Antibiotic associated colitis
- MRSA infections
Target trough concentration of vancomycin
10-15 mg/ml
15-20 mg/ml for endocarditis
When should vancomycin be stopped?
Tinnitus
(Ringing sound in ears)
Most common side effect associated with vancomycin
thrombophlebitis
Pain and inflammation at injection site
Examples of tetracycline
- Democycline
- Doxycycline (used in malaria and chlamydia)
- Lymecyline
Side effects of tetracycline
’POST’
- Photosensitivity
- Oesophageal irritation
- Severe headaches (benign intracranial hypertension)
- Tooth discolouration
- Visual disturbances
When to stop tetracycline
Headache or visual disturbances
When are tetracyclines contraindicated
- Children under 12
- Pregnancy and breastfeeding
Deposits in growing bone and teeth and cause tweety discolouration and dental hypoplasia
Side effect of minocycline
- Irreversible pigmentation
- Greater risk of lupus-erythematosus-like syndrome
- Dizziness and vertigo
What two tetracyclines can be used in renal impairment
’DM’
Doxycycline
Minocycline
Tetracyclines in hepatic impairment
Avoid - hepatotoxicity
What tetracyclines cause photosensitivity
‘Double Ds’
Doxycycline
Democycline
What tetracyclines do you avoid ingestion remedies with
‘Dox Like Milk’
Doxycycline
Lymecycline
Minocycline
+ Azithromycin (tabs)
2 hours before and after
What tetracyclines are avoided with milk
‘DOT’
- Democlocycline
- Oxytetracycline
- Tetracycline
What tetracyclines need to be swallowed whole and taken standing with a full glass of water
‘DMT’
- Doxycycline
- Minocycline
- Tetracycline
+ clindamycin
When to avoid quinolones
MRSA - Innate resistance
When are quinolones used?
Lower RTI
UTIs
Examples of quinolones
Ciprofloxacin
Levoflaxacin
Moxifloxacin
Nalidixic acid
Main side effect of quinolones
QT prolongation
Esp. Moxifloxacin (associated with life threatening hepatotoxicity
Side effects of quinolones
- QT prolongation
- Seizures
- Tendon damage
- Heart valve regurgitation
- Aortic aneurysms
Quinolones in pregnancy
Avoid - Arthropathy
When to discontinue quinolones
- Psychiatric, neurological and hypersensitivity reactions occur
- Tendonitis
When should quinolones be avoided
- Pregnancy
- Children / adolescents
Drug interaction with quinolones that increase risk of QT prolongation
- SSRI
- quinine
- Amiodarone
- macrolides
- antipsychotic
Drug interaction with quinolones that increase risk of seizures
- ciproflaxacin
- theophylline
- NSAIDs
Main drug interactions with quinolones
- QT Prolonging drugs - increased risk of QT prolongation
- Corticosteroid - risk of tendonitis or tendon damage
- Methotrexate - increase methotrexate levels
- NSAIDs - increased risk of seizures
- Theophylline - increased theophylline levels
Counselling points for quinolones
- Driving; can impair performance of skilled task (enhanced by alcohol)
- Antacid and zinc/iron; Leave 2 hours before or after taking
How is azithromycin taken
OD
Before food/ indigestion remedies: 2 hour gap
How is ezithromycin taken
QDS/BD
Before indigestion remedies: 2 hour gap
How is clarithromycin taken
BD
Common side effect of clarithromycin
Taste disturbances
When is azithromycin commonly used?
Chlamydia
1g STAT - OTC
Gonorea
Side effects of macrolides
- GI effect (most common with erithromycin)
- QT prolongation
- Hepatotoxicity
- Ototoxicity
How to take macrolides
exception?
Take with or after food
(Azithromycin before food)
What is used in treating H.pylori infections
Macrolides (clarithromycin BD)
Nature of interaction between clarithromycin and warfarin
Increased risk of bleeding
Nature of interaction between clarithromycin and statin
Increased risk of myopathy
Stop statin while on clarithromycin - no need to refer
When is benzylpenicillin used?
Meningitis
When is phenyl penicillin used?
Respiratory tract infection in children
eg. Sore throat, tonsillitis
How is Flucloxacillin given?
Before food
What type of infection is Flucloxacillin inactive against?
MRSA
When are PipTaz used?
Serious infections
- septicaemia
- complicated UTI
- HAP
How is stomach bug treated?
Self limiting
So not typically treated
How is C.Diff treated
Vancomycin
Fedoxamicin
10 - 14 days
What it contraindicated in diarrhoea related to colitis
Loperamide - worsens infection
How is endocarditis treated
Amoxicillin/ ampicillin + low dose gentamicin
- if pen allergy; low dose gentamicin + vancomycin
Treatment: endocarditis with staphylococci origin or streptococcus
Staph: Flucloxacillin
Strept: Benzylpenicillin
Treatment: community acquired pneumonia
-Amoxicillin - 7 days
- Alt. Clarithromycin or doxycycline
Treatment: hospital acquired pneumonia
Early onset; co-amoxiclav
Alt: Doxycycline, Cefa, co-trimoxazole, levoflaxacin
tx for 7 days
Treatment: blind tx of meningitis
Benzylpenicillin or Cefotaxime
Chloramphenicol - pen allergy
Treatment: pneumococci meningitis
Cefotaxime (+ dexamethasone)
Benzylpenicillin
Cephalosporin + vancomycin - pen allergy
Treatment: meningitis listeria
- amoxicillin / ampicillin + gentamicin
- Co-trimoxazole - pen allergy
Treatment: osteomyelitis (bone infection)
Flucloxacillin - 10 - 14 days
Clindamycin - pen allergy
Treatment: septic arthritis
Flucloxacillin 4-6 weeks
Treatment: impetigo (skin)
- Hydrogen peroxide
- fuscidic acid
Wide spread: Flucloxacillin
7 days tx course
Treatment: cellulitis
Flucloxacillin
Near eye: co-amoxiclav
Clarithromycin + metronidazole
Severe: Clindamycin
Treatment: leg ulcer
Flucloxacillin
Clar/ erythro/ doxy - pen allergy
Co-trimoxazole
Treatment: animal and human bite
Co-amoxiclav - 14 days
Doxycycline + metronidazole - pen allergy
Treatment: mastitis during breast feeding
Flucloxacillin - 10-14 days
Erythromycin - pen allergy
Treatment: dental infection
Metronidazole 200mg TDS for 3 days
Alt. Amoxicillin
Treatment: bacterial sore throat
Phenoxymethylpenicillin
Symptoms of sinusitis
Pain in the hollow of cheekbones
Nasal congestion
Treatment: diabetic foot infection
Flucloxacillin
- PO 7 days in mild
- IV for >48 hours in severe
Alt - clarithromycin/ doxycycline/ erythromycin
Treatment: otitis external
- Flucloxacillin
- Clarithromycin/ Azithromycin/ erythromycin
Treatment: otitis media
- Amoxicillin
- Co-amoxiclav (worsening symptoms)
- Clarithromycin/ erythromycin - pen allergy
How long does tuberculosis treatment last for?
6 months
Split into 2 phases
What is involved in first phase of TB treatment and how long does it last
‘RIPE’ - 2 months
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol
Pt counselling: Rifampicin
- report signs of hepatotoxicity
- colours soft contact lenses
- urine red/ orange
Pt counselling: Isoniazid
- report signs of hepatotoxicity
- peripheral neuropathy (overcome with pyridoxine)
Pt counselling: Ethambutol
Report visual changes
Which TB drug is not hepatotoxic
Ethambutol
Side effect of ketoconazoles
Fatal hepatotoxicity
- not used in fungal infections
Side effect of itraconazol
- heart failure
- hepatotoxicity
interacts with antacids
Side effect of voriconazole
- Phototoxicity and hepatotoxicity
- Skin cancer (avoid direct sunlight and sunlamps. Use high factor SPF and carry alert card)
Side effect of amphoteracin B
Nephrotoxicity
specify brand
Used in serious fungal infections and may cause anaphylaxis
Treatment: oral thrush
- Nystatin (POM)
- Miconazole (daktarin oral gel) - OTC
Treatment: vaginal thrush
- Oral fluconazole (single dose)
- topical imidazole (clotrimazole)
Treatment: tinea
- miconazole
- clotrimazole
- terbinafine (athlete foot)
What is used to treat athletes foot
Terbinafine
Treatment: fungal nail infection
Amorolfine
Treatment: herpes
Aciclovir
Prophylaxis of influenza virus
Oseltamivir
start with 48 hours of exposure and reduces symptoms by 1 day
Bites prevention
- NETS impregnated with permethrin is most effective
- DEETS 20-50% (applied to the skin eg. Spray or lotion) - safe and effective in adults and children > 2 months
- Apply sunscreen first and use SPF 35-50
Doxycycline counselling in malaria
- Take 1-2 days before entering area and continue for 4 weeks after leaving
- Protect skin from sunlight
- Do not take indigestion remedies
- Swallow whole with plenty water while sitting or standing
- Take with meals
Side effect of mefloquine
- Serious neuropsychiatric reactions - STOP
- Dizziness (care with driving)
Length of malaria prophylaxis before travel and exceptions
1week before
Exception:
- **Mefloquine **; 2-3 weeks
- Malorone & Doxycycline; 1-2 days
Length of malaria prophylaxis before travel and exceptions
4 weeks after
Exception:
- Malarone; 1 week after
Long term prophylaxis duration of malaria
- > 5 years: chloroquine and proguanil
- 2 years: doxycycline
- 1 year: mefloquine, malarone
What is malarone made of
Atovaquone
Proguanil
Malaria drugs to avoid in epilepsy
Chloroquine
Mefloquine
Malaria drugs to avoid in renal impairment
- proguanil
- malarone and chloroquine (eGFR <30)
Choice of malaria drug in renal impairment
Doxycycline
Mefloquine
Malaria drugs to avoid in pregnancy
- Mefloquine
- Malarone (may be given in 2nd/3rd trimester if no other option)
- Doxycycline - Contraindicated
Anti malaria in pregnancy
- Chloroquine
- Proguanil (give 5mg folic acid)
Anti malaria and warfarin
- Start 2-3 weeks before
- INR should be stable before departure
- Monitor INR before, after 7 days of prophylaxis and after completing course
- For prolonged stay, check INR frequently
What is used to treat falciparum malaria
- Quinine
- Malarone
- Riamet
What is used to treat non-falciparum malaria
Chloroquine
When is quinine used in malaria treatment
- Only if medical care is not accessible in 24 hours of fever onset
- Give with written instructions that urgent help is required of fever >38 degrees, 7 days or more after arriving in malarious zone
Nature of interaction between carbapenems and valproate
Decrease blood concentration of valproate
higher risk of seizure - Avoid
What is the most effective barrier protection against mosquitoes
Mosquito nets impregnated with permethrin
What penicillins should be taken on an empty stomach
an hour before food or 2 hours after
- Phenoxymethylpenicillin
- Ampicillin
- Flucloxacillin
Sildenafil and doxycycline
Space dose at least 2-3 hours apart
Antibiotic safe to take with quetiapine in Pen allergy
Doxycycline
What is used to treat conjunctivitis in eye
Chloramphenicol
Fusidic acid if pen allergy
Scarlet fever
Strawberry tongue
Sand paper rash
phenoxymethylpenicillin
Thread word tx
Mebendazole
Cause of menengitis
Strept pneumonia
Chloramphenicol OTC
2+ years
Conjunctivitis