Bacillus cereus bacteremia associated with contaminated Alcohol Prep Pads: Outbreak investigation followed by international product recall

Background: Bacillus cereus Group and Bacillus species not cereus Group have caused healthcare-associated outbreaks of invasive disease.  Pseudo-outbreaks due to contaminated products have also been described.  B. cereus and Bacillus spp. are resistant to killing by alcohol.  Alcohol prep pads (APPs) are supplied both as sterile and non-sterile.  The non-sterile products may not be clearly labeled and may be mistakenly assumed to be sterile by users because they are intended for antisepsis.  From Mar – Nov 2010, The Children’s Hospital (TCH), Aurora, CO had 20 cultures positive with B. cereus.  Nine of these were from blood. Two cases of severe infection in Oct/Nov. prompted an outbreak investigation.    

Objective: Determine a possible source of the B. cereus positive cultures.

Methods: Breaches in procedural and surgical techniques, common interventions and products were explored.  Three common products were tested: sterile syringes pre-filled with sterile saline solution, sterile applicators with a 2% chlorhexidine gluconate/70% alcohol solution for skin prep, and wipes packaged with 70% isopropyl alcohol (APPs) not labeled as either “sterile” or “non-sterile”. The internal contents and outside package of non-sterile APPs from 10 different lots manufactured by Triad Group^®, Hartland, WI were allowed to air dry and then cultured in Tryptic Soy Broth.  Internal contents of “sterile” APPs from a different manufacturer were also cultured. Gram-positive rods recovered from APPs were identified as either B. cereus or as Bacillus spp.  The Diversilab System was used to compare patient and APP isolates.  Independent PFGE analysis was performed by CDPHE. Findings were reported to CDC and FDA.

Results: Bacterial cultures of 3 saline syringes and its liquid and pads from 9 packages of chlorhexidine gluconate/alcohol applicators were negative.  No breaches in infection prevention practices were identified.  Bacillus cereus and other Bacillus spp. were cultured from the internal contents of 80% of the “non-sterile” APPs with 8 of 10 lots culture positive. The outside of the "non-sterile" APPs grew Bacillus spp. from 95% of the packages. Bacillus spp. was cultured from 10% of the initial set of “sterile” APPs tested but subsequent cultures were negative. No patient strains matched strains from the APPs. However, indistinguishable strains were found between some lots of APPs and from repeated culture of the same lot of APPs. These results were supported by independent PFGE analysis.

Conclusions:  APPs from Triad Group were contaminated with Bacillus.  The product was internally recalled and replaced with sterile APPs from another manufacturer.  There have been no further cases identified at TCH.  On January 3, 2011 Triad voluntarily recalled its alcohol prep products due to potential contamination.^5,6  Healthcare facilities, providers and users of APPs should avoid using non-sterile APPs.