Comparison of Flocked and Rayon Swabs for Detection of Nasal Carriage of Staphylococcus aureus among Pathology Staff Members

Abstract

Comparison of flocked swabs (E-swabs; Copan) to the standard rayon swabs (Copan) was undertaken for detection of Staphylococcus aureus nasal carriage among staff at Dorevitch Pathology in Heidelberg, Melbourne, Australia. Among 100 volunteers, 36 were found to be colonized with S. aureus by one or both swab results. The prevalence detected by E-swabs was 35%, and the prevalence through rayon swabs was 34% (95% confidence interval [CI] for the difference in proportions, ؊12 to 14). Thirty-three volunteers tested positive with both types of swabs, while 2 were detected on E-swabs alone and another on rayon swab testing alone. There was no evidence of a significant difference in carriage detected by E-swabs or rayon swabs.Staphylococcus aureus is a common cause of infections in the community and a major cause of hospital-associated morbidity (18). Colonization is well described, with up to 30% of the population thought to be carriers (7,16,18), and is associated with a higher risk of infection in the hospital setting (2,4,9,11,12,15,17,18). The anterior nares have been shown to be the most frequent site of carriage and therefore a single site for detection (9,10,18). Nasal carriage is defined as "persistent" or "intermittent or noncarriage," with persistent carriers showing an increased risk of infection, compared with intermittent carriers who share the same low risk as noncarriers (13). Given the clinical relevance, it is imperative to use the best swab system which would provide the highest yield in detecting nasal carriage. Flocked swabs have been described as improving uptake of epithelial cells and, therefore, microorganisms and viruses (1,5,6,14), but are more expensive than standard rayon swabs, so it is therefore worth investigating whether there is evidence that E-swabs perform better in detecting nasal carriage.Aims. This study was designed to determine if there is a difference in the performance of E-swabs over standard rayon swabs in detecting nasal carriage of S. aureus among healthy adult staff volunteers at a pathology service in Melbourne, Australia.Ethics approval was gained from The University of Melbourne Human Research Ethics Committee (identification no. 0826852). Volunteers were recruited from staff based at Dorevitch Pathology in Melbourne.All volunteers were sequentially allocated a study identification number, and individual results remained anonymous. Each volunteer had sampling from each naris with both swabs (E-swab and Rayon swab; Copan). To ensure that equal numbers of participants were swabbed with each swab type, participants with odd study numbers were sampled with an E-swab first (right then left naris) followed by the rayon swab and those with even study numbers were swabbed in the reverse order. The swab sequence was therefore captured in the study identification number, allowing us to investigate whether swab sequence was important and to control for potential bias associated with swab sequence. Laboratory staff involved in isolating S. aureus were blinded to the swabbing seque...

Better Detection of Staphylococcus aureus Nasal Carriage by Use of Nylon Flocked Swabs

“…Similarly, Van Horn et al have demonstrated that nylon flocked swabs placed in Amies liquid medium yielded greater organism release (18). In contrast to these results, a recent study from De Silva et al (8) did not find any difference in the determination of S. aureus nasal carriage when comparing flocked swabs to rayon swabs; however, those authors used a different microbiological procedure than ours, consisting of an overnight preenrichment broth step, followed by plating on chromogenic agar. The latter process is known to improve the sensitivity of bacterial detection (3,10,13,15), but it is timeconsuming since the results are delayed by 1 day, which may be a determinant for the detection of nasal carriers when decontamination treatment must be applied to prevent S. aureus infection, for instance, just before a surgical procedure (4) or the arrival of the patient in an intensive care unit.…”

“…In comparison to the use of rayon swabs, the use of flocked swabs has been demonstrated to improve the uptake of epithelial cells and viruses (1,7), to release more microorganisms in vitro (18), and to enhance the molecular detection of Chlamydia trachomatis and Neisseria gonorrhoeae (6). Despite these apparent advantages, a recent study that compared flocked and rayon swabs after a 24-h broth culture enrichment did not show any difference in the rate detection of S. aureus nasal carriers (8). To further assess the utility of flocked swabs, we conducted a study similar to that mentioned just above, with the exception that no enrichment step was performed.…”

“…The latter process is known to improve the sensitivity of bacterial detection (3,10,13,15), but it is timeconsuming since the results are delayed by 1 day, which may be a determinant for the detection of nasal carriers when decontamination treatment must be applied to prevent S. aureus infection, for instance, just before a surgical procedure (4) or the arrival of the patient in an intensive care unit. In addition, De Silva et al provided no data relative to the amount of bacteria recovered by each type of swab (8).…”

Comparison of ESwab with Traditional Swabs for Detection of Methicillin-Resistant Staphylococcus aureus Using Two Different Walk-Away Commercial Real-Time PCR Methods

“…Several studies have demonstrated the superior absorption and releasing capacity of ESwabs, in comparison with traditional swabs (13)(14)(15)(16)(17)(22)(23)(24). The ESwab is a revolutionary concept because of its ability to offer what standard swabs cannot provide; ESwabs elute the entire sample into 1 ml of transport medium, providing identical aliquots of liquid sample suspension, which enables laboratories to determine and to validate the optimal specimen volumes (and therefore analyte amounts) for use in their assays.…”

A comparison of flocked swabs and traditional swabs, using multiplex real-time PCR for detection of common gastroenteritis pathogens in Botswana

“…rotavirus) the mean nucleic acid yield was actually higher with the traditional swabs, this would suggest that sequence of sample collection did not always disadvantage the second swab. Several paired swab studies of other mucosal surfaces have shown that sequence of swab collection did not significantly affect sensitivity for pathogen detection (18, 19). One possible reason that the flocked rectal swab outperformed the traditional swab for Shigella detection is that it has a “stopper” at 3.2cm mark and this might aid in ensuring adequate sampling at the rectal mucosa (where Shigella causes pathology).…”