Comparison of an Automated Plate Assessment System (APAS Independence) and Artificial Intelligence (AI) to Manual Plate Reading of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus CHROMagar Surveillance Cultures.

The automated plate assessment system (APAS Independence; Clever Culture System, Bäch, Switzerland) is an automated imaging station linked with interpretive software that detects target colonies of interest on chromogenic media and sorts samples as negative or presumptive positive. We evaluated the accuracy of the APAS to triage methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus cultures using chromogenic medium compared to that by human interpretation. Patient samples collected from the nares on ESwabs were plated onto BD BBL CHROMagar MRSA II and BD BBL CHROMagar Staph aureus and allowed to incubate for 20 to 24 h at 37°C in a non-CO2 incubator. Mauve colonies are suggestive of S. aureus and were confirmed with latex agglutination. Following incubation, samples were first interrogated by APAS before being read by a trained technologist blinded to the APAS interpretation. The triaging by both APAS and the technologists was compared for accuracy. Any discordant results required further analysis by a third reader. Over a 5-month period, 5,913 CHROMagar MRSA cultures were evaluated. Of those, 236 were read as concordantly positive, 5,525 were read as concordantly negative, and 152 required discordant analysis. Positive and negative percent agreements (PPA and NPA, respectively) were 100% and 97.3%, respectively. The APAS detected 5 positive cultures that were missed by manual reading and determined to be true positives. In a separate analysis, 744 CHROMagar Staph aureus plates were read in parallel. Of these, 133 were concordantly positive, 585 were concordantly negative, and 26 required discordant analysis. PPA and NPA were 95.7% and 96.7%, respectively. This study confirmed the high sensitivity of digital image analysis by the APAS Independence such that negative cultures can be reliably reported without technologist intervention (negative predictive values [NPVs] of 100% for CHROMagar MRSA and 99.0% for CHROMagar Staph aureus). Triaging using the APAS Independence may provide great efficiency in a laboratory with high throughput of MRSA and S. aureus surveillance cultures.

Saving costs through the decontamination of the packaging of unused medical supplies using hydrogen peroxide vapor.

OBJECTIVE. Individually packaged sterile supply items may become contaminated and act as vectors for nosocomial transmission of multidrug-resistant organisms (MDROs). Thus, many hospitals have a policy to dispose of these unused, packaged supply items at patient discharge from the hospital, which has considerable cost implications. We evaluated the frequency of contamination of these items, the efficacy of hydrogen peroxide vapor (HPV) in disinfecting them, and costs associated with discarded supplies. DESIGN. Before-after study. METHODS. A pilot study was performed in the rooms of 20 patients known to be colonized or infected with vancomycin-resistant enterococci (VRE), and a follow-up study was performed in an additional 20 rooms of patients under precautions for various MDROs in 6 high-risk units. Five pairs of supply items were selected. One item of each pair was sampled without exposure to HPV, and the other was sampled after HPV exposure. The cost of discarded supplies was calculated by examining stock lists of supplies stored on the study units. RESULTS. Seven (7%) of 100 items were contaminated with VRE in the pilot study, and 9 (9%) of 100 items were contaminated with MDROs in the follow-up study. None of the items were contaminated after exposure to HPV (P < .02 in both the pilot and the follow-up study). The annual cost of supplies discarded at patient hospital discharge was $387,055. This figure does not include the cost of waste disposal and is therefore likely to be an underestimation of the financial burden. CONCLUSIONS. HPV effectively disinfected the packaging of supply items, which could generate considerable financial and environmental benefits.