Pathology stewardship – an essential element of AMS

Poor antimicrobial prescribing decisions often are triggered by laboratory results that create red herrings or worse.  Inappropriate/ poor specimen collection and/or a request form that provides no context to the investigation often sets the ball rolling.  Inappropriate workup and reporting of contaminant or colonising isolates may then follow (it may be impossible for the lab to judge in the absence of clinical notes or context).  Reports that publish susceptibility results on contaminant bacterial or fungal isolates or unneeded results for broad spectrum agents often then prompt treatment and potentially prolong hospital stays (see this recent reference for a great example of why ‘cascade’ reporting is warranted- it can reduce usage and resistance!).

And so, we recognise that some sort of pathology stewardship is an essential element of antimicrobial stewardship programs. 

We previously highlighted an article that examined inappropriate pathology ordering in Australia and New Zealand.  The article was written in response to significant increases in workload and evidence from the UK that  25% of all pathology requests were unnecessary or inappropriate.  Spelman surveyed  140 Australian and New Zealand infectious diseases physicians and medical microbiologists as to what they considered the most useless of microbiology tests.  Pet peeves included (see also Box 1 below):

  • Tests ordered with results that are never reviewed by the clinician.
  • Single samples taken for serological diagnosis without subsequent convalescent sera submission.
  • Serological fishing expeditions – requests for tests where there is no supporting clinical illness or epidemiological link.
  • Dry swabs submitted for bacterial culture.  Swabs instead of pus or tissue submitted from surgical procedures.
  • Environmental swabs collected in the absence of epidemiological evidence of a local healthcare infection issue.
  • Tests for ‘clearance’, such as repeat throat and nose swabs for respiratory viruses or repeat stool tests for Clostridium difficile.

Spelman gives a great introduction into pathology stewardship – definitely worth a read! Box 2 below summarises some of his suggestions for improvement. 

ozbugozbug-2ozbug-3References

  • National Coalition of Public Pathology. Encouraging quality pathology ordering in Australia’s public hospitals. Final report. Sydney: NCOPP, 2012. http://www.ncopp.org.au/UserFiles/file/NCOPP%20QUPP%20Project%20Final%20Report%20(web).pdf
  • Spelman, Denis. “Inappropriate pathology ordering and pathology stewardship.” The Medical journal of Australia 202.1 (2015): 13-15.
  • United Kingdom Department of Health. Report of the second phase of the review of NHS pathology services in England. Chaired by Lord Carter of Coles. 2008.

2 comments

  1. Colleen Allen · · Reply

    Is there any justification for using Tazocin as first line treatment for sepsis. Every time I phone through positive blood culture grams and ask re current antibiotics I am told patient has been started on Tazocin. Why?

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    1. Hi Colleen, thanks for the comment.

      Antibiotic choice in sepsis depends on several different factors but in particular the source of sepsis.

      For example, the Therapeutic Guidelines recommend piperacillin+tazobactam 4+0.5 g (child: 100+12.5 mg/kg up to 4+0.5 g) IV, 6-hourly as a first line empirical treatment for febrile neutropenic patients with suspected sepsis. The general principle is that rapid initiation of broad-spectrum antimicrobials will cover both common pathogens and high morbidity/mortality pathogens (in particular in the immunocompromised). This is of course until susceptibility results come through to guide directed therapy.

      Similarly, Hunter New England LHD policy on ED management of adults receiving chemotherapy with symptoms or signs of potential sepsis recommend piperacillin/tazobactam 4+0.5 g IV 8-hourly as a preferred first line.

      If the source of sepsis is not apparent in the immunocompetent, gentamicin + flucloxacillin is first line treatment (more comprehensive gram negative and positive cover combined compared to tazocin).

      However when the source of infection is apparent, antibiotic choice for severe sepsis or septic shock is guided by the usual susceptibility of common pathogens associated with that source. For example, for sepsis with apparent sources including but not limited to surgical site infections, parapneumonic effusions and diverticulitis , the Therapeutic Guidelines recommends piperacillin+tazobactam 4+0.5 g IV, 6-hourly in patients requiring IV antibiotics longer than 72 hours.

      The patient’s history also guides antibiotic choice. For example, in patients who develop spontaneous bacterial peritonitis while receiving prophylaxis with trimethoprim+sulfamethoxazole or norfloxacin, streptococcal and enterococcal infections are more common. To give at least some sort of evidence-based direction to therapy, guidelines recommend piperacillin+tazobactam compared to ceftriaxone 2g daily (the usual first line treatment for SBP) because cephalosporins are not active against enterococci.

      In summation, there are very specific scenarios in which piperacililn+tazobactam MAY be a suitable empirical or directed antibiotic treatment for sepsis. Unfortunately, piperacililn+tazobactam is not always strictly used for these situations alone and some practitioners may lean towards using broad spectrum antibiotics rather than the antibiotic of choice. Overuse of empirical tazocin can be frustrating, but fortunately pathology susceptibility results can help to lessen the exasperation!

      – Sim

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