A comparison of real-time PCR positivity rates for Bordetella pertussis between specimens collected with rayon swabs on an aluminum wire shaft in Amies gel with charcoal and those collected with flocked swabs in universal viral transport medium during an epidemic revealed that their performances were comparable.
Since Jules Bordet and Octave Gengou first isolated Bordetella pertussis, the bacillus responsible for whooping cough, in 1906 using their specific medium, named Bordet-Gengou agar (1), the laboratory diagnosis of pertussis has greatly improved with increased sensitivity of detection and a shorter time to diagnosis. The introduction of nucleic acid amplification testing (NAAT), which is faster and more sensitive than culture for the detection of B. pertussis in respiratory specimens, has revolutionized the laboratory diagnosis of pertussis (2). It has also permitted new collecting devices, like flocked swabs in universal transport medium (UTM), to be considered for the collection and transport of specimens for B. pertussis testing. The nylon-flocked swab provides better entrapment during collection and better release of microorganisms than do other swabs (3, 4, 5). However, no studies evaluating the performance of flocked swabs in UTM as collecting devices in the detection of Bordetella by NAAT have been published.(This study was presented in part at the 113th General Meeting of the American Society for Microbiology, Denver, CO, 18 to 21 May 2013.)When PCR testing for the detection of B. pertussis in respiratory specimens was introduced in our laboratory, validation studies with spiking experiments, serial dilutions, and determinations of the lower limit of detection were performed to validate the acceptability of flocked swabs in UTM as a collection device (data not shown). To further evaluate the performance of the flocked swabs in UTM, we compared the real-time PCR positivity rate for B. pertussis between specimens collected with the BD BBL CultureSwab Plus Amies gel with charcoal and BD universal viral transport medium with flocked swabs during a pertussis epidemic to assess if one was superior to the other.The study was initiated during an epidemic of B. pertussis in Minnesota and was conducted over a period of 6 months, from 26 June to 31 December 2012. The specimens were sent mainly from local pediatric and family practice clinics and from a university children's hospital. In general, the transportation time was Ͻ24 h. The caregivers had the choice of sending nasopharyngeal wash or nasopharyngeal swab specimens for B. pertussis testing by PCR. If they chose to send a nasopharyngeal swab specimen, they then chose one of two main collection devices, the rayon swab in Amies gel with charcoal or the flocked swab in UTM.The BD BBL CultureSwab Plus Amies gel with a charcoal unit consists of a regular rayon wound-fiber tip on an aluminum wire shaft and a transport tube with Amies gel enriched with charcoal. The BD universal viral transport system comprises a package containing a peel pouch incorporating ...