Copan ESwab™, the first Liquid Based Microbiology device, preserves microbial viability up to 96/120 hours
Although it is recommended that swabs specimens should be processed soon after collection, delays are occurring due to microbiology laboratory consolidation. Specimens transport to centralized laboratories results in long storage times, samples accumulation and increasing workload. Therefore the use of a preservation medium that supports microbial viability for prolonged storage time is necessary. ESwab™ (ES), a high release flocked swab combined with one ml of liquid Amies medium, is the first liquid based microbiology (LBM) collection and preservation system that provides a homogeneous specimen suspension and allows multiple testing from the same original sample. The objective of the study was to compare the ability of ES to Amies Agar Gel Transystem (TS) to maintain the viability of a panel of microorganisms for an extended period of time. T=24h T=120h T=24h T=120h T=24h T=120h.
Method: A panel of ATCC microorganism strains, representative of different body sites infections, was tested. P. anaerobius (PA), S. pneumoniae (SP), B. fragilis (BF), H. influenzae (HI) were selected for the respiratory system; VRE for the gastrointestinal system; S. pyogenes (SPY), P. acnes (PAC) for the skin membrane system; C. albicans (CA), for the genital tract system; MRSA for multi-site infections. Each strain was serially titrated and each swab was loaded with 100uL inoculum, to obtain 300-500CFU from each time zero (T0) plate. After inoculation, the swabs were held at room temperature (RT) for the first 24h, refrigerated for the following 72/96h and plated every 24h.
Results: Colonies count was recorded for each strain for all storage times. HI in ES was viable up to 120h but negative in TS, SP, BF, SPY, PA and PA at 96h in TS. CA, MRSA and VRE were stable up to 120h in both device, but TS had one log reduction. Testing of additional 10 microorganisms is in progress and results will be reported later. In some cases at T0, recovery rate of ES was up to 20% higher than TS.
Conclusion: ES was superior to TS in maintaining bacterial viability for longer time and had a higher colonies count than the TS. The ES with its ability to maintain the original microbial load up to 96/120h can be used for the collection of clinical specimens that require longer processing time, multiple testing and results confirmations.