A sleuth story Patricia Cornwall would appreciate

Microbes, a Pharmacy Clean Room, Waste Bins, ATP, and a keen-eyed pharmacist

Recently I was part of a trio who presented an intriguing case-study of a microbiological contamination issue in a pharmacy clean room – it took months to solve, and ATP proved an excellent tool.

Tyler Weaver, Josh Guinter (Children’s Hospital of Philadelphia) and I delivered our paper entitled “Resolving microbial contamination of reusable waste bins in a pharmacy clean-room” at the Sept Association for the Healthcare Environment (AHE) conference in Pittsburg PA.

We are soon to publish – in meantime click here to view our PowerPoint presentation.

The story in a nutshell…

  Within a hospital, a Pharmacy Clean Room (PCR) is where sterile medications are prepared for patients – it is an “inner sanctum” with restricted access and is regularly tested for microbes to ensure all surfaces are scrupulously decontaminated to an ISO Standard – at a level higher than operating rooms.

A recent failure in a PCR resulted in 753 patients being infected with 64 deaths across 20 USA states.

The problem

  • PCR work-surfaces are required to be regularly tested for microbes. Two tests in PCR exceeded allowable level – triggering immediate action
  • Surfaces and ducts were scrupulously cleaned – but tests failed a second time. Several weeks of investigations proceeded
  • Then a keen-eyed pharmacist noticed a gown-tie moving as it hung from a waste bin in the PCR
  • Tie-movement meant air-flow; airflow meant bugs could waft in air – perhaps bin was source?
  • The reusable bins were tested, found to have very high microbial counts, and bin-vendor A was asked to remedy

The remedy

  • Microbe tests are expensive, so bins were ATP-tested as surrogate (ATP detects microbes and other living cells)
  • Bin-vendor A could not reduce ATP count to target-level  of <250 Relative Light Units (RLU) – aver of highest counts was 14,844 RLU
  • Second vendor (Vendor B) supplied bins for testing – all passed – aver of highest counts was 103 RLU – hospital changed to Vendor B for PCR.
  • No further PCR work-surface tests failed.

The explanation

  • Vendor A supplied bins “nested”. Entrapped moisture in bottom bin enabled microbial growth
  • When pushed into bin, discarded gowns created “piston effect” liberating microbial aerosol which wafted onto PCR work-surface
  • Vendor B wash process had higher level of bin decontamination. Bins supplied individually, not nested.
  • In 4 years: bins have exceeded ATP threshold of 250 RLU occasionally, and none since Aug 2015; no failures in PCR work-surface microbe tests have occurred.

Take Home Messages

  • Vendors of reusable bins have differing wash, drying  and delivery processes. Ask for details of processes and ATP-test (particularly if for PCR use).
  • ATP testing using a threshold of 250 RLU is a useful adjunct for checking QA of external waste bins used in PCR