A study of various commercially available transport swabs for the recovery of fastidious organisms
Abstract number: R2224
Objectives: The Sigma Transwab ® is a liquid medium transport swab and uses 1ml of Liquid Amies Transport medium, which is based on the original formulation of Amies, but without the charcoal and is intended for processing by some of the new automated plating systems. The swab is foam tipped which allows the flow through of the liquid medium, reagents and microorganisms, thus increasing the sensitivity and recovery of organisms. The preliminary study used the principles of CLSI's M40-A standard, inoculating the swabs with specified dilutions of target organisms, and holding at either room temperature or 40C. For the preliminary study the organisms used were: Staphylococcus aureus, Haemophilus influenzae, b Haemolytic Streptococcus. Fresh overnight cultures were used in each case. The organisms were from Clinical specimens not NCTC or ATCC organisms.
Method: A McFarland standard 0.5 was made in sterile 0.85% saline from a fresh overnight culture of each of the organisms used.
Tenfold dilutions were made for the viability studies from the 0.5 McFarland's standard.100ul of these dilutions were lawned on to the appropriate agar plate to ensure the organism was viable from the saline dilution and used as the Growth Control. The 105, 106 and 107 cfu/ml dilutions were used to inoculate the swabs with 100ul (0.1 ml) using 3× 1/2 tubes. The swab was placed in the 100ml inoculum for 10 seconds and then returned to the transport media. Swabs were kept at room temperature and at 4 0C for the following holding times. 515 minutes (Zero Time), 4 hours, 24 hours, 48 hours, and 72 hours. Each set of dilutions were performed in duplicate. On completion of the holding time, the swab inoculated on to a plate appropriate to the organism (Blood agar, Chocolate blood agar) in a lawn and incubated in the appropriate atmosphere Aerobically at 370 C for Staphylococcus aureus and b haemolytic streptococcus, and CO2 at 370 C for Haemophilus influenzae. The plates read and colonies counted manually at 24 and 48 hours.
Results and Conclusion: The initial results showed that recovery was seen for all the organism/dilution/temperature combinations at 24 hours, and for most at 48 hours, and that Sigma Transwab ® would be a suitable transport device for these organisms. Further studies will be done and data presented for other organisms using more fastidious organisms, and a comparison of results obtained with standard transport swab devices (Eurotubo, Spain and Technical Service Consultants, UK).
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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