Wasted spectrum 101 – amoxicillin+clavulanate overuse

Amoxicillin+clavulanate (Augmentin) is an important broad spectrum agent that includes Gram negative anaerobic coverage (see below). We rely on it for a variety of complex infections, often as a second line.

Compared with amoxycillin alone, the incidence of gastrointestinal, hepatic and haematological side effects is significantly higher for amoxicillin+clavulanic acid. It may be associated with a higher risk of Stevens-Johnson syndrome, purpura and hepatitis.  Superinfections with Clostridium difficile in (community or hospital) are also a significant risk.

Common circumstances of misuse and recommended (eTG) alternative approaches:

 

 Syndrome Indicated first line alternative to amoxicillin+clavulanate
Otitis media

Acute sinusitis

Wait and see delayed script approach

Amoxycillin.  See also.

Acute pharyngitis Wait and see delayed script approach +/- throat swab to confirm group A strep in child

Phenoxymethylpenicillin.  See also.

Acute on chronic obstructive pulmonary disease (COPD) Symptomatic management dependent on asthma presence etc.

Doxycycline OR  amoxycillin short course– reserve for severe exacerbations

Acute bronchitis or post viral cough syndrome Avoid antibiotic therapy– post viral cough lasts 2-3 weeks usually!
Cellulitis Flucloxacillin or dicloxacillin

Cotrimoxazole or doxycycline if MRSA implicated

Skin/Soft tissue infection (boils) Incision and drainage. See also.
Acute uncomplicated diverticulitis Avoid antibiotic therapy
Urinary tract infection

 

Use trimethoprim or cephalexin due to lower side effects

Direct therapy against demonstrated pathogen

Comparative spectra – what does the clavulanate add in fact?

Category Bacterial species Amoxycillin

% susc

Amox+clav

% susc

Relevance
Gram negative E. coli

Klebsiella pneumoniae

~40%

0%

~ 80%

~ 80%

Treatment of UTI / intra-abdominal infections
Enterobacter-like species* 0%

 

=

 

No advantage

 

Bacteroides group (Gram negative anaerobes) < 20%

 

~ 95%

 

Intra-abdominal infections, diabetic foot infection
Haemophilus influenzae

Moraxella catarrhalis

70%

< 5%

~ 95%

100 %

Reserved for second line or treatment failure.

(These organisms frequently represent colonisers in resp. tract)

Pasteurella multocida 100% = No advantage; anaerobic cover valuable for animal bites however
Gram positive Streptococcus pneumoniae (non CNS infection) 90%

 

=

 

No advantage

 

Streptococcus pyogenes (group A) and other beta haemolytic streptococci 100%

 

=

 

No advantage

 

Staphylococcus aureus (MSSA)

 

20%

 

100%

 

NOT drug of choice – use dicloxacillin or cephalexin
Staphylococcus aureus (MRSA)

 

0%

 

=

 

No advantage

 

Enterococcus faecalis

Enterococcus faecium

~ 95%

0 %

=

=

No advantage

 

Peptostreptococci and other Gram positive anaerobes 100%

 

=

 

No advantage

 

* Includes Enterobacter cloacae, Serratia species, Citrobacter freundii, Morganella morganii and related species

References

  • Australian Therapeutic Guidelines: Antibiotic, edition 15, 2014
  • Salvo F et al.  Adverse drug reactions related to amoxicillin alone and in association with clavulanic acid: data from spontaneous reporting in Italy. J Antimicrob Chemother. 2007 Jul;60(1):121-6.

2 comments

  1. […] WASTED SPECTRUM 101 – AMOXICILLIN+CLAVULANATE OVERUSE seemed to touch a chord providing examples of situations where use of this agent is unnecessary and also unpacking the differential susceptibility of different type of bacteria to amoxycillin versus amox+clav […]

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  2. […] previously counselled against augmentin overuse in a number of conditions which did not, however, include intra-abdominal infection where the new […]

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