Evaluation of bacterial recovery and viability from three different swab transport systems

doi:10.1097/PAT.0000000000000074

Pathology

Volume 46, Issue 3, April 2014, Pages 230-233

https://doi.org/10.1097/PAT.0000000000000074 Get rights and content

Summary

This study evaluated three types of swab transport systems for organism recovery. Swabs with transport media were further assessed for organism viability over 24 hours over a range of different storage temperatures. Test organisms consisted of aerobes, fastidious aerobes and anaerobes. Swabs were tested according to the standardised quantitative elution method published by the Clinical Laboratory Standards Institute (CLSI; M-40A). There were substantial differences in primary organism recovery with recovery rates from different swabs ranging from <0.1% to 78% for Streptococcus pyogenes. Similar differences were noted for other test organisms. In general, the flocked swab (ESwab) demonstrated highest rates of recovery for aerobic organisms, while higher rates of recovery of Fusobacterium nucleatum were demonstrated from a standard swab (Transwab). When considering organism viability, no single swab fulfilled all the criteria stipulated by the M-40A standard for all organism/temperature combinations. Organism viability was marginally better for the gel-based swab transport systems as compared to the liquid-media based ESwab. Significant differences between swab transport systems were demonstrated, including differences for primary organism recovery and viability. The ESwab showed the best recovery of organisms, while gel-based media demonstrated marginally better bacterial viability for most tested retention times and temperatures.

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There are more references available in the full text version of this article.

Cited by (9)

Comparison of the certified Copan eSwab system with commercially available cotton swabs for the detection of multidrug-resistant bacteria in rectal swabs
2022, American Journal of Infection Control
Rectal swabs are well-implemented screening tools for multidrug-resistant bacteria (MDRB). Since certified swabs such as the Copan eSwab system experienced a delivery bottleneck during the COVID-19 pandemic, commercially available alternatives such as commonly used double-tipped cotton swabs had to be investigated, especially considering their similarity to professional cotton swabs for microbiological purposes.
Diagnostic properties of commercial cotton swabs (comparable to Q-tips) and Copan eSwabs were qualitatively compared in a prospective single-center study using microbiological standard cultures and PCR methods for the detection of multidrug-resistant Gram-negative bacteria and vancomycin-resistant enterococci (VRE).
A total of 196 swab pairs were collected from 164 participants. MDRB were detected in 36 of 164 cases (22%). There were neither false-negative nor false-positive results using commercial cotton swabs. In 8 of 196 samples (4.1%) MDRB species were detected only by using cotton swabs, including vancomycin-resistant Enterococcus faecium, OXA-48 producing Escherichia coli, ESBL-producing Klebsiella pneumoniae and ESBL-producing Escherichia coli.
Commercial cotton swabs turned out to be a reliable alternative to Copan eSwabs. For practical use as a screening tool, relevant storage- and manufacturer-related contamination must be ruled out beforehand.
Commonly available double-tipped cotton swabs can be used for rectal MDRB screening in the event of supply shortages of certified swabs. Further studies should clarify their suitability as a sampling system for nasopharyngeal MRSA carriage or even for the molecular biological detection of SARS-CoV-2.
A comparison of cotton-tipped and nylon flocked swabs for culture of Neisseria gonorrhoeae from oropharyngeal samples
2021, Diagnostic Microbiology and Infectious Disease
Citation Excerpt :
Several studies have shown the ESwab system from Copan (a nylon flocked swab that is immediately placed in Amies medium after sampling) further increases bacterial recovery and enhances bacterial culture performance compared to direct plating,(Saegeman et al., 2011) and other swabs and transport media. ( Nys et al., 2010; Tan et al., 2014; Warnke et al., 2014b) There has been increasing use of ESwab for diagnostic testing of STIs.( Williamson et al., 2019) It is possible that the ESwab system could improve culture positivity of N. gonorrhoeae compared to the dry FLOQSwab on its own.
Our aim was to determine if there was a difference in culture positivity for oropharyngeal gonorrhoea when sampling using a nylon-flocked versus cotton-tipped swab. We collected FLOQSwabs and cotton-tipped swabs from individuals aged ≥ 18 years who had untreated oropharyngeal gonorrhoea detected by NAAT between November 2019-June 2020.Of 78 participants, 32 (41.0%) were culture-positive for N. gonorrhoeae from either swab. Of these 32, 29 (90.6%, 95%CI: 75.0%-98.0%) were positive on both swabs, one (3.1%, 95%CI: 0.0%-16.2%) tested positive on FLOQSwab only and two (6.2%, 95%CI: 0.1%-20.8%) tested positive on cotton-tipped swabs only. There was moderate agreement between the swabs in the amount of bacterial growth (Cohen's Kappa (k)=0.745; 95%CI: 0.622-0.868, p<0.001). Our results showed that the proportion of positive results was comparable using the FLOQSwabs versus the cotton-tipped swabs for oropharyngeal gonorrhoea culture.
Cross-country transport and isolation and identification of Streptococcus pneumoniae by use of alternate sources of blood supplemented media among laboratories in India
2019, Indian Journal of Medical Microbiology
Background: The isolation of S. pneumoniae (Sp) depends on specimen integrity / transport, media and expertise. The non-availability of sheep blood agar poses a challenge in identification of colonial morphology and identification in India. Methods: Laboratories processed swabs containing either pure Sp or Sp in mixed cultures with a second (confounding) bacterium shipped across the country in cold conditions. Duplicate set of swabs was shipped back to the central laboratory to assess the impact of shipping on culture viability. The identical swab was cultured on sheep, human blood and one additional agar plate used in the laboratory. Results: 46/60(77%) of cultures containing only Sp were correctly identified. In specimens where Sp was present in mixed culture, the proportion of isolates in which Sp was correctly identified varied, with most variability attributed to the particular confounding organism rather than the media. There was no discernible impact of temperature-controlled (4-6°C) transport on the isolation of Sp from culture swabs. Conclusions: The study clearly elucidates the ability of laboratories for isolation of S. pneumoniae on human blood agar in resource limited settings. The results highlight the difficulties inherent in correctly identifying pathogens in mixed cultures in needs improvement using standardized tests across the study centers. The study also reaffirms the ability to transport biological specimens over long geographical distances without loss.
Rapid detection of Group B streptococcus directly from vaginal–rectal specimens using liquid swabs and the BD Max GBS assay
2017, Clinical Microbiology and Infection
Citation Excerpt :
This has increased the potential to detect GBS directly from clinical specimens without the need for pre-enrichment when PCR is used. A number of studies have shown that nylon flocked swabs are superior to, and have a higher sensitivity than, the traditional cotton-tipped rayon swabs [21–23] for a number of different bacteria, including GBS [24]. Verhoeven et al. demonstrated that these flocked swabs attained a greater sensitivity in the detection of Staphylococcus aureus compared with rayon swabs (97.1% versus 74.3%) and also yielded larger amounts of bacteria in quantitative cultures, particularly in cases of low in vivo bacterial loads [25].
We adapted the BD Max GBS assay, an automated platform for the detection of Group B streptococcus (GBS) DNA in vaginal–rectal swab specimens after LIM broth enrichment, to directly detect GBS in specimens collected using cellular foam swabs in Amies liquid medium. We compared the BD Max GBS assay performance to that of enriched culture and the BD GeneOhm StrepB assay.
Seventy-two reference vaginal–rectal specimens were employed to determine the limit of GBS detection and the preferred test volume for direct detection of GBS. A total of 304 clinical specimens were then tested by the optimized BD Max GBS assay, both by direct testing and following broth enrichment.
The limit of GBS detection was 75 CFU/mL and the preferred test volume was 100 μL. Of 304 clinical specimens tested, GBS was detected in 62 specimens by enriched culture (20.4%); 61 of these yielded GBS by the BD Max GBS assay when performed directly from the liquid swab (sensitivity 98.4%). All 242 culture-negative specimens also yielded negative results by the BD Max GBS assay (specificity 100%). When this assay was performed following broth enrichment, GBS was detected in all 62 culture-positive specimens (100% sensitivity). The sensitivity and specificity of the BD GeneOhm StrepB assay was 90.3% and 99%, respectively.
The BD Max GBS assay is highly sensitive, requires minimal technical skill with <2 min required to set-up, and results are available in under 80 min (versus 24–48 h for culture). It is configured for ‘on demand’ testing and vaginal–rectal specimens can be rapidly screened for GBS without the need for enrichment. The results obtained in this study demonstrate that rapid GBS screening using the BD Max GBS assay at the time of delivery is a viable alternative to the current recommended screening at 35–37 weeks of gestation with pre-enrichment testing methods.
Reply of the authors
2015, Journal of Microbiological Methods
Influences of swab types and storage temperatures on isolation and molecular detection of Mycoplasma gallisepticum and Mycoplasma synoviae
2020, Avian Pathology

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Evaluation of bacterial recovery and viability from three different swab transport systems

Summary

Diagn Microbiol Infect Dis

Quality Control of Microbiological Transport Systems: Approved Standard

Comparison of Copan eSwab with the Copan Venturi Transystem for the quantitative survival of Escherichia coli, Streptococcus agalactiae and Candida albicans

Eur J Clin Microbiol Infect Dis

Comparison of the Copan ESwab system with two Amies agar swab transport systems for maintenance of microorganism viability

J Clin Microbiol