The impact of sample storage on molecular-based detection of Mycoplasma genitalium

G L Murray; J P Su; J Birnie; J Danielewski; D A Machalek; C S Bradshaw; T R H Read; A-M Costa; S M Garland

doi:10.1111/jam.14359

The impact of sample storage on molecular-based detection of Mycoplasma genitalium

J Appl Microbiol. 2019 Oct;127(4):1219-1223. doi: 10.1111/jam.14359. Epub 2019 Jul 2.

Authors

G L Murray^{1

2

3

4}, J P Su², J Birnie², J Danielewski^{1

2}, D A Machalek^{1

2

5}, C S Bradshaw^{5

6

7}, T R H Read^{6

7}, A-M Costa^{1

8}, S M Garland^{1

2

4}

Affiliations

¹ Centre for Women's Infectious Diseases, The Royal Women's Hospital, Park Parkville, Vic, Australia.
² Molecular Microbiology Research Group, Murdoch Children's Research Institute, Parkville, Vic, Australia.
³ Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Vic, Australia.
⁴ Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Vic, Australia.
⁵ Centre for Epidemiology and Biostatistics, School of Population and Global Health, University of Melbourne, Vic, Australia.
⁶ Melbourne Sexual Health Centre, Alfred Health, Carlton, Vic, Australia.
⁷ Central Clinical School, Monash University, Melbourne, Vic, Australia.
⁸ The Royal Children's Hospital, Parkville, Vic, Australia.

PMID: 31220405
DOI: 10.1111/jam.14359

Abstract

Aims: Mycoplasma genitalium causes a common, sexually transmitted bacterial infection. This study assessed the detection of M. genitalium in stored urine samples to understand the impact of sample storage on M. genitalium detection.

Methods: Aliquots of M. genitalium-positive urine (n = 20 patients) were stored at either room temperature (22°C) or 4°C, without a preservative. At weekly intervals, samples were tested using the commercial test ResistancePlus MG^® (SpeeDx^® , Australia). We report the analysis at 1 week, an acceptable collection-to-test turnaround time, with further analysis over 5 weeks to illustrate degradation trends.

Results: After storing at 4°C, the proportion of specimens that remained positive for M. genitalium was 100% after 1 week and 95% after 4 weeks. Storage at 22°C led to more rapid decline in detection in the first 4 weeks, with 95% detected after 1 week and 85% at 2 weeks onwards. At 5 weeks, samples stored at both temperatures had an 85% M. genitalium detection rate, with increase in crossing points (Cq) of 0·72 (95% confidence interval (CI) 0·01-1·43; P-trend = 0·027) at 4°C, and 1·75 ((95% CI 0·79-2·71), P-trend <0·001) at 22°C.

Conclusions: Urine samples stored without preservative, and unfrozen, retained high M. genitalium detection levels over the short term (up to 5 weeks). To minimize degradation, storing at 4°C is recommended.

Significance and impact of the study: There is little known about the stability of clinical samples for M. genitalium detection. This study found that a high proportion (85-100%) of samples are still suitable for M. genitalium detection after storage for up to 5 weeks.

Keywords: PCR; degradation; detection; diagnosis; molecular genetic.

MeSH terms

Australia
Humans
Molecular Typing*
Mycoplasma Infections* / diagnosis
Mycoplasma Infections* / microbiology
Mycoplasma genitalium* / genetics
Mycoplasma genitalium* / isolation & purification
Specimen Handling*
Urinalysis*

Abstract

MeSH terms

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