Let's talk about antibiotics

Antimicrobial stewardship conversations across Northern NSW, Australia

Stratum corneum


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Is it cellulitis? The case of itchy red legs

66 year old woman with 12 month history of itchy red  legs.

She dated the start of the problem from an excision of a skin lesion from the left shin.  She notes persistent redness occurring over both lower legs, more marked on the left side, and this has been associated with marked itchiness after showering.  She was receiving antibiotics for a presumed cellulitis and also had been using a topical steroid cream.

Past history of bilateral vein stripping years ago and she experiences a degree of swelling in both lower legs that arises through the day and both the swelling and redness settles overnight.  No history of claudication nor other sort of leg pain or paraesthesia. Background of stable hypertension on medication.   

On examination there was noticeable pigmentation over both lower legs with much solar skin damage and moderate pitting peripheral pedal oedema to the ankles bilaterally.  The skin was red and shiny with areas of excoriation on both sides (photos). No tenderness nor warmth was present to suggest cellulitis.  Continue reading

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Acute otitis media- clarifying the role of antibiotics – a new case study from NPS-MedicineWise

National Case Study – Otitis Media: Clarifying the role of antibiotics – this was released by NPS-MedicineWise in May 2016. The expert commentary is provided by Prof. Chris Del Mar. The case study is customised for the profession of the participant: GP, Pharmacist, Nurse or ‘other’.

Other case studies of interest from NPS: 

Clinical e-audits from NPS: 

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Acute sinusitis and sore throat in primary care – what evidence?

An excellent paper by Professor Chris Del Mar in Australian Prescriber unpacks the Cochrane reviews on the (quite minimal) value of antimicrobial treatment of these conditions.  The evidence level is quite robust.  For a summary, see below.

It couples nicely with a recent pragmatic randomized controlled trial that examined the  effectiveness of steam inhalation and nasal irrigation for chronic or recurrent sinus symptoms in primary care, published in the CMAJ.  This showed moderate significant long-term efficacy for nasal irrigation. Steam inhalations were NOT effective.  Continue reading

strep pyogenes


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Extrapolating antibiotic susceptibility for streptococci including the pneumococcus

This posting concerns betahaemolytic species of streptococci including S. pyogenes (Lancefield group A strep), S. agalactiae ((group B strep), S. dysgalactiae group (betahaemolytic large colony, groups C or G) (several species included) which are usually associated with pyogenic infection, especially of skin and soft tissue.   S. pneumoniae (the pneumococcus ) is also considered. 

A key misunderstanding about Streptococcus pneumoniae is the significance of penicillin ‘resistance’ and how it is detected.  Oxacillin is used because it provides the best sensitivity for detection of minor elevation of the penicillin minimal inhibitory concentration (MIC) that may be associated with failure of meningitis treatment. Note that benzylpenicillin, ampicillin or amoxycillin remain highly effective therapy for non-meningeal infection (e.g. pneumonia) caused by strains with lowered susceptibility (raised MIC), unless the MIC is (unusually) >=4mg/L when an alternative agent should be selected.   For a useful review of the situation in regards betalactam and macrolide resistance see this 2007 review by Keith Klugman and the paper by Schentag et al referenced below.

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Cipro


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Sparing fluoroquinolones – alternative safe and effective options by syndrome and bug

Fluoroquinolones (ciprofloxacin, norfloxacin and moxifloxacin) have serious potential side effects and are best used only for directed therapy of serious multi-resistant Gram negative infections where no other safer alternatives are available.

14 of our 32 hospital facilities in HNELHD overuse these agents with 2016 average FQ usage above our current benchmark of 30 defined daily doses per 1000 patient-days.

Here are some pointers to situations where better alternatives to FQ exist:

Gram negatives

In hospital practice, FQ are often used for proven susceptible infections due to Pseudomonas aeruginosa,  Enterobacter cloacae and Enterobacter aerogenesSerratia marcescens, Citrobacter freundii, Proteus vulgaris, Providentia species and Morganella morganii (the so called ‘ESCPPM’ group) because there are few or no other oral antibiotic alternatives.

Alternatives:

  • Trimethoprim+sulfamethoxazole is an attractive alternative for ESCPMM organisms as susceptibility is high in HNELHD (avoid this drug in the elderly however).
  • In uncomplicated UTI, use trimethoprim for susceptible ESCPPM group organisms.
  • For non-typhoidal Salmonella infection, use oral amoxycillin or trimethoprim+sulfamethoxazole- local strains are nearly always susceptible to one or both

Always consider whether these organisms are really causing infection since they frequently colonise the skin, respiratory tract,  other mucous membranes and urinary catheters or bladder.

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