Comparative performance of sponge versus flocked swabs for culture-based and metagenomic detection of microbial contamination in the healthcare environment.

Abstract

Background: Identifying optimal methods for sampling surfaces in the healthcare environment is critical for future research requiring the identification of multidrug-resistant organisms (MDROs) on surfaces.

Methods: We compared 2 swabbing methods, use of a flocked swab versus a sponge-stick, for recovery of MDROs by both culture and recovery of bacterial DNA via quantitative 16S polymerase chain reaction (PCR). This comparison was conducted by assessing swab performance in a longitudinal survey of MDRO contamination in hospital rooms. Additionally, a laboratory-prepared surface was also used to compare the recovery of each swab type with a matching surface area.

Results: Sponge-sticks were superior to flocked swabs for culture-based recovery of MDROs, with a sensitivity of 80% compared to 58%. Similarly, sponge-sticks demonstrated greater recovery of Staphylococcus aureus from laboratory-prepared surfaces, although the performance of flocked swabs improved when premoistened. In contrast, recovery of bacterial DNA via quantitative 16S PCR was greater with flocked swabs by an average of 3 log copies per specimen.

Conclusions: The optimal swabbing method of environmental surfaces differs by method of analysis. Sponge-sticks were superior to flocked swabs for culture-based detection of bacteria but inferior for recovery of bacterial DNA.