Influence of Drying Condition and Other Aspects on Recovery of Pseudomonas aeruginosa in the PN-EN 14561 Carrier Test

Pseudomonas aeruginosa is a bacterium sensitive to desiccation. Its use in disinfectant testing methods is important given its association with hospital-acquired infections. According to PNEN 14561:2008, obtaining a sufficient number of P. aeruginosa cells on a glass test surface under clean conditions after the drying process is essential for evaluating the bactericidal effectiveness of disinfectants. Does reducing the drying temperature of glass carriers contaminated with P. aeruginosa under clean conditions from the standard-recommended 37°C ± 1°C to 24°C ± 1°C improve bacterial recovery after drying? The recovery of P. aeruginosa from glass surfaces after drying was performed by the procedure specified for the water control, as outlined in PN-EN 14561:2008. Additionally, in the 24°C ± 1°C, the glass carriers were inoculated onto TSA medium, whereas at 37 °C ± 1°C the number of P. aeruginosa was determined in hard water following the contact time. The mean recovery of P. aeruginosa (6.37 log ± 0.12 log) was significantly higher in the 24°C ± 1°C variant compared to the 37°C ± 1°C variant (5.60 log ± 0.24 log). At 24°C ± 1°C, P. aeruginosa remained on the glass carrier after recovery, whereas at 37°C ± 1°C, the bacteria were detected in hard water. Lowering the drying temperature did not allow recovery of P. aeruginosa at the level required by PN-EN 14561:2008. The reduction in P. aeruginosa recovery resulted from bacterial detachment into hard water and retention on the carrier surface.