ESwab™ Supports Viability of Clinical Strains of Anaerobes for Extended Times

BACKGROUND:
Preservation of anaerobes during transport is a major challenge for the Microbiology laboratory. ESwab™ (Copan Italia, Brescia, Italy) is a Liquid Based Microbiology (LBM) device that consists of a tube with 1.0 ml of liquid Amies medium with a FLOQSwab^®. ESwab™ can be used for the collection and preservation of clinical specimens for the detection of bacteria with both manual and WASP™ automation streaking methods.
OBJECTIVE:
The objective of this study was to evaluate the performance of ESwab™ to support the viability and stability of anaerobic bacteria strains during room temperature storage.
METHODS:
In this validation 185 clinical anaerobe isolates were used, including 33 bacteria classes, supplied by the Institute of Medical Microbiology (IMM) of the University of Zurich.
• Each bacteria strain was inoculated into an ESwab™ device, shipped at room temperature from Zurich to Copan in Brescia Italy, and received after 1 week.
• Each strain was first plated on blood agar plates using a 30ul loop using both manual and WASP inoculation methods in order to verify culture viability and purity.
• Plates were incubated at 370C under anaerobic condition and read after 48 hours incubation.
• Using a 1ul loop, a single bacteria colony from the blood culture of each strains was inoculated in an ESwab™ (medium+ flocked swab).
• After vortexing 30ul from each inoculated ESwab™ were plated on Schaedler agar plates at zero time as baseline and after 24, 48, 72, 96,120 hours, 7 and 14 days at room temperature.
• Plates were incubated at 370C under anaerobic condition and read after 48 hours.

RESULTS
All 185 clinical anaerobes had growth on blood agar after 48 hours. Out of 185 clinical strains, 113 were positive with pure bacteria growth, 51 were positive with less than 50 Colonies; while 21 had mixed growth and 4/21 were lost after passaging. The 181 anaerobe clinical strains stored in ESwab™ were positive after 24, 48, 72, 96,120 hours, 7 and 14 days at room temperature.

The data obtained in this validation demonstrated that the ESwab™, supports the viability of a wide range of anaerobic bacteria up to 2 weeks storage at room temperature. The Copan ESwab™ is a suitable device for the collection and transportation of clinical specimens for the detection of anaerobic bacteria and can be used with manual and WASP™ and WASPLab^® automated culture streaking.

Acknowledgement:
We are grateful to Prof. Erik C. Böttger, Dr Michael Hombach and Dr Maria Senn from the Institute of Medical Microbiology of the University of Zurich for providing the anaerobe clinical strains.