Antibiotic Prescribing Guidelines

Original article by Tom Leach | Last updated on 22/1/2016
Printer-friendly version
These guidelines are intended to give a basic overview of the types of antibiotic used to treat various kinds of infection. They should not be used as clinical guidelines. Resistance patterns and drug approvals vary from country to country and as such national and / or local guidelines should be used wherever possible. If uncertainty still exists, you may wish to contact your local infectious diseases consultant for specific advice.

Key:

  • First line
  • Second line
  • Third line
  • Penicillin allergy alternative (generally this is erythromycin or clarithromycin)
Remember that the doses below are adults doses; children’s doses (and also the drugs used for children) may be different.
 
Condition
Drug
Dose
Info
 
 
 
 
 
U
R
O
L
O
G
Y
UTI – uncomplicated
Nitrofurantoin – and fluids
Trimethoprim – and fluids
Cefalexin – and fluids
Co-amoxiclav/ciprofloxacin used for resistant organisms
MRSA – nitrofurantoin and trimethoprim and doxycycline
50mg qds - 3 days
200mg bd – 3 days
500mg bd – 3 days
Nitro drugs is contra-indicated when GFR <50, so be careful in the elderly!
 
always assume in men that a UTI is complicated until proven otherwise
 
Acute Prostatitis
Ciprofloxacin
Trimethoprim
Tetracycline
500mg bd – 28 days
200mg bd – 28 days
500mg bd – 28 days
 
Pyelonephritis (and complicated UTI’s)
Ciprofloxacin / cefuroxime
Co-amoxiclav
IV – gentamycin
500mg bd – 7 days
625mg tds – 14 days
5mg/Kg when pathogen unknown
Nitrofurantoin is NOT effective.
Genital bacterial infections (General)
Metronidazole
400mg bd 5-7 days
 
Metronidazole
Doxycycline
400mg bd 14 days
100mg bd 14 days
 
Doxycycline
100mg bd 7 days
Can also give Azithromycin one off dose to increase compliance
Ciprofloxacin
Amoxicilin
Probenicid
500mg single dose
3g single dose
1g single dose
 
Herpes virus
(and for freq. Reccur.)
Aciclovir
Aciclovir
200mg x5 for 5 days
400mg bd – 6 months
Herpes virus also causes shingles. In which case, give 800mg x5, for 5 days
Vaginal fungal infections
Clotrimazole pessary
500mg – single dose
 
 
R
E
S
P
I
R
A
T
O
R
Y
Lower respiratory tract infection (LRTI) in previously well patients
Amoxicillin
Erythromycin
500mg tds – 10 days
1g bd – 10 days
Amoxicillin can cause allergic reaction in those allergic to penicillin. Clarithromycin is the alternative used normally.
COPD acute exacerbation
Amoxicillin
Co-amoxiclav
Ciprofloxacin
Clarithromycin
500mg tds - 7 days
625mg tds – 7days
500mg bd – 7 days
500mg bd – 7 days
 
Erythromycin
500mg qds – 14 days
 
--------------------------
-------------------------
A LRT infection usually in the first 2 years of life. Viral; don’t give antibiotics!
Amoxicillin
Doxycycline
500mg tds – 14 days
100mg bd 14 days
 
0 – Amoxicillin (clarithro)
 
1 – Amoxicillin + clarithro.
2- IV Amox. + clarithro.
3-5 – IV augmentin + clarith
1g (500mg) single dose, or 500mg (500mg) – 7 days
500mg (each) – 7 days
1g IV + 500mg IV – review @ 24hours
Treatment is dependent on CURB 65 score.
 
 
E
N
T
Otitis Media
Amoxicillin
Erythromycin
Co-amoxiclav
500mg tds – 10 days
250mg qds – 5 days
375mg tds – 5 days
Special rules apply for children (often antibiotics are not used
Otitis Externa
Topical:
Oral:
 
For fungus:
Locorten-viofrom
Betnesol-N
Flucloxacillin
Erythromycin
Clotrimazole 1% soln
3 drops bd - 7days
3 drops qds – 7 days
250mg qds – 7 days
250mg qds – 7 days
3 drops tds – 4 weeks
Don’t forget anaesthesia – it is very painful! If this condition is recurrent consider underlying pathology such as diabetes, or exfoliative skin conditions.
Dental infections(gingivitis and abscess)
Penicillin V – AND –
Chlorohexidine mouthwash
Erythromycin
Metronidazole
500mg qds – 5-7 days
10 ml bd
500mg qds – 5-7 days
400mg tds – 5-7 days
 
Pharyngitis
Penicillin V
Erythromycin
500mg qds – 7 days
1g bd – 7 days
Remember – most sore throats are viral and you should not prescribe anything – see the algrythmn. It is estimated up to 75% of patients are prescribed antibiotics – probably due to patient expectations and the doctor not wanting to let them down
Nystatin (can be pastille or suspension)
Fluconazole (tablet)
100k units 4xday – 7days
 
50mg od – 7-14 days
Remember – this is common in immunosupressed individuals.
Fluconazole can also be used in loads of other fungal infections
Acute Sinusitis
Amoxicillin
Oxytetracycline
500mg tds – 5 days
250mg qds – 5 days
 
 
 
S
K
I
N
Animal and human bites
Co-amoxiclav
375 tds – 7 days
Cat and dog bites are generally infected with anaerobic bacteria
Impetigo / Cellulitis
Flucloxacillin
Fusidic acid cream
Clarithrymycin
Erythromycin
500mg qds – 5-14 days
Qds – 5 days
500mg bd 7-14 days
Consider combining both oral and topical treatments. When cellulitis, give flucoloxacillin and penicillin.
Benzoyl peroxide cream +/-
Clindamycin / tetracycline
Oxytetracycline
doxycycline
This is not an antibiotic.
If infected
500mg bd – 3 months+
100mg od – 3 months+
Only give antibiotics when this is infected.
MRSA colonation / infection AND/OR patient systemically unwell
Vancomycin IV –AND-
Oral ciprofloxacin
 
500mg bd
Make sure you give two antibiotics! Also advisable to cover infected area with iodine or chlorohexadine dressing
Fungal hair skin and nails
Various topical and oral agents – too many to list
FLUCONAZONE – is probably the most widely used agent.
Fluconazole is given once weekly
Mastitis
Metronidazole
 
 
Necrotising Fascitis
Give all of the following:
Vanomycin IV
Clindamycin IV
Ciprofloxacin IV
 
 
900mg tds
400mg  bd
Do this whilst you are waiting for advice! Seek urgent surgical and microbiological advice
 
 
 
 
 
 
 
 
 
 
 
 
G
I
Primary care:
1)Salmonella / shingella
2)Campylobacter
 
1)Ciprofloxacin
 
2)Erythromycin
3)Metronidazole
 
500mg bd - 3 days
 
500mg bd – 3 days
2g od – 3 days
The vast majority are self- limiting and do not require intervention. When causatory organism is not known, use ciprofloxacin. Note that the public health department needs to be notified of all cases of food poisoning. Also remember that many antibiotics can cause diarrhoea! – by killing the ‘good’ bacteria, and allowing the resistant strains to multiply .
 
Metronidazole is good because it is good at attacking anaerobic bacteria.
 
Amoxicillin – AND –
Gentamycin – AND –
Metronidazole
Vancomycin (instead of amoxicillin)
1g IV tds
5mg/Kg od
500mg IV tds
Use 3 antibiotics!
Intra-abdominal sepsishospital acquired
 
Oral continuation:
Peperacillin – AND –
Gentamycin
 
Amoxicillin – AND –
ciprofloxacin – AND –
Metronidazole
 
 
4.5g IV tds
5mg/Kg od
 
500mg tds
500mg bd
400mg tds
Consider MRSA – particularly if hospital acquired. If it is present use IV vanomycin
-
-
Should be managed surgically, and antibiotics only used when there are signs of systemic infection
Severe Acute pancreatitis
-
-
Very severe disease requires antibiotic therapy. Usually involving co-amoxiclav / amoxicillin.
 
Sepsisthis is a word that basically means serious systemic inflammation caused by infections (SIRS). The term septicaemia is an older word that has a similar meaning.
Tazocin*
Gentamicin
4.5g every 8 hours
5mg/Kg – but – only use if there is septic shock with hypotension
Patients in shock and who are seriously ill should be started on fluid replenishment and antibiotics right away without waiting for any test results.
 
 
O
T
H
E
R
S
Trauma
Flucloxacillin IV +
Metronidazole IV
OR – if more serious
Co-amoxiclav IV
1g 6hrs – review@24hrs
500mg 8 hrs
 
1.2g tds – 3 days+
These treatments are prophylactic for bone/joint infections.
Isoniazid
Rifampicin
Pyrazinamide
Ethambutol
300mg od – 6 months
600mg od – 6 months
2g daily – 2 months
15mg/Kg od – 2 months
Ethambutol can be omitted if HIV negative, and low risk of isoniazid resistance (i.e. no previous treatment for TB) there are several combination pills available for use after discharge from hospital
Ceftriaxone IV
Chloramphenicol
2g bd until improvement, then
3g od
All patients with suspected meningitis need to receive the first dose within 30 minutes of arrival
 
 
Indolent (not acutely unwell)
Benzylepenicillin IV +
Gentamicin IV
Acutely unwell (or IV drug user)
Flucloxacillin IV
 
1.2g 6x a day
1mg/Kg 3x a day
 
2g qds if <85Kg
2g 6xday >85Kg
Note that the dose of flucloxacillin varies with patient’s weight.
Flucloxacillin +
Amoxicillin
clarithromycin
1g qds
500mg qds
500mg bd
 
*brand name for piperacillin + tazobactam combination
 
 
Score
Mortality
0.7%
1
2%
2
9%
3
14%
4
40%
5
57%
C – confusion (new confusion)
U- Urea >7
R – Respiratory rate >30
B – BP <90(sys) or 60(dias)
65 – age over 65
 
Each criteria is worth 1 point
 
 
Of all the antibiotics, only METRONIDAZOLE reacts with alcohol. It will cause severe vomiting and GI disturbance if alcohol is taken with the drug.
However, you should still advise patients that taking alcohol with antibiotics may prolong the recovery time, as it is generally a toxin.