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Open Access Research article

Mailed versus frozen transport of nasal swabs for surveillance of respiratory bacteria in remote Indigenous communities in Australia

Kerry-Ann F O’Grady1*, David M Whiley2, Paul J Torzillo34, Theo P Sloots25 and Stephen B Lambert67

Author Affiliations

1 Queensland Children’s Medical Research Institute, Queensland University of Technology, Herston Road HERSTON QLD, 4029 Herston, Australia

2 Queensland Paediatric Infectious Diseases Laboratory, Queensland Children’s Medical Research Institute, The University of Queensland, Herston, Australia

3 Sydney Medical School, University of Sydney, Sydney, Australia

4 Nganampa Health Service, Anangu Pitjantjatjara Yankunytjatjara, Alice Springs, Australia

5 Sir Albert Sakzewski Virus Research Centre, Royal Children’s Hospital, Herston, Australia

6 Queensland Children’s Medical Research Institute, The University of Queensland, Herston, Australia

7 Communicable Diseases Branch, Queensland Health, Brisbane, Australia

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BMC Infectious Diseases 2013, 13:543  doi:10.1186/1471-2334-13-543

Published: 14 November 2013

Abstract

Background

Surveillance programs and research for acute respiratory infections in remote Australian communities are complicated by difficulties in the storage and transport of frozen samples to urban laboratories for testing. This study assessed the sensitivity of a simple method for transporting nasal swabs from a remote setting for bacterial polymerase chain reaction (PCR) testing.

Methods

We sampled every individual who presented to a remote community clinic over a three week period in August at a time of low influenza and no respiratory syncytial virus activity. Two anterior nasal swabs were collected from each participant. The left nare specimen was mailed to the laboratory via routine postal services. The right nare specimen was transported frozen. Testing for six bacterial species was undertaken using real-time PCR.

Results

One hundred and forty participants were enrolled who contributed 150 study visits and paired specimens for testing. Respiratory illnesses accounted for 10% of the reasons for presentation. Bacteria were identified in 117 (78%) presentations for 110 (79.4%) individuals; Streptococcus pneumoniae and Haemophilus influenzae were the most common (each identified in 58% of episodes). The overall sensitivity for any bacterium detected in mailed specimens was 82.2% (95% CI 73.6, 88.1) compared to 94.8% (95% CI 89.4, 98.1) for frozen specimens. The sensitivity of the two methods varied by species identified.

Conclusion

The mailing of unfrozen nasal specimens from remote communities appears to influence the utility of the specimen for bacterial studies, with a loss in sensitivity for the detection of any species overall. Further studies are needed to confirm our finding and to investigate the possible mechanisms of effect.

Clinical trial registration

Australia and New Zealand Clinical Trials Registry Number: ACTRN12609001006235.

Keywords:
Respiratory bacteria; RT-PCR; Specimen transport; Laboratory methods