GONORRHOEA

A cluster of culture positive gonococcal infections but with false negative cppB gene based PCR

G Lum¹, K Freeman¹, N L Nguyen², E A Limnios², S N Tabrizi³, I Carter², I W Chambers⁴, D M Whiley⁵, T P Sloots⁵, S M Garland³ and J W Tapsall²

¹ Department of Microbiology, Royal Darwin Hospital, Casuarina, Northern Territory, Australia
² Microbiology Department, South Eastern Area Laboratory Services, Sydney, New South Wales, Australia
³ Department of Microbiology, Royal Women’s Hospital, Melbourne, Victoria, Australia
⁴ Douglass Hanly Moir Pathology, Ryde, New South Wales, Australia
⁵ Clinical Virology Research Unit, Sir Albert Sakzewski Virus Research Centre, Royal Children’s Hospital and Health Service District Brisbane, Queensland, Australia

Correspondence to:
Correspondence to:
J W Tapsall
Department of Microbiology, The Prince of Wales Hospital, Randwick, New South Wales, Australia 2031; j.tapsall{at}unsw.edu.au

Objectives: To describe the prevalence and characteristics of isolates of Neisseria gonorrhoeae grown from urine samples that produced negative results with nucleic acid amplification assays (NAA) targeting the cppB gene.

Methods: An initial cluster of culture positive, but cppB gene based NAA negative, gonococcal infections was recognised. Urine samples and suspensions of gonococci isolated over 9 months in the Northern Territory of Australia were examined using cppB gene based and other non-cppB gene based NAA. The gonococcal isolates were phenotyped by determining the auxotype/serovar (A/S) class and genotyped by pulsed field gel electrophoresis (PFGE).

Results: 14 (9.8%) of 143 gonococci isolated were of A/S class Pro^–/Brpyut, indistinguishable on PFGE and negative in cppB gene based, but not other, NAA.

Conclusions: This cluster represents a temporal and geographic expansion of a gonococcal subtype lacking the cppB gene with consequent loss of sensitivity of NAA dependent on amplification of this target. Gonococci lacking the cppB gene have in the past been more commonly associated with the PAU^-/PCU^- auxotype, a gonococcal subtype hitherto infrequently encountered in Australia. NAA based on the cppB gene as a target may produce false positive as well as false negative NAA. This suggests that unless there is continuing comparison with culture to show their utility, cppB gene based NAA should be regarded as suboptimal for use either as a diagnostic or supplemental assay for diagnosis of gonorrhoea, and NAA with alternative amplification targets should be substituted.

Abbreviations: AGSP, Australian Gonococcal Surveillance Programme; A/S, auxotype/serovar; NAA, nucleic acid amplification assays; PAU^-/PCU, proline-arginine-uracil/proline-citrulline-uracil; PCR, polymerase chain reaction; PFGE, pulsed field gel electrophoresis

Keywords: cppB gene; Neisseria gonorrhoeae; nucleic acid amplification assay

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• Tapsall, J. W., Limnios, E. A., Murphy, D., on behalf of the Australian Gonococcal Surveillanc, (2008). Analysis of trends in antimicrobial resistance in Neisseria gonorrhoeae isolated in Australia, 1997 2006. J Antimicrob Chemother 61: 150-155 [Abstract] [Full Text]  
• Whiley, D. M., Limnios, E. A., Ray, S., Sloots, T. P., Tapsall, J. W. (2007). Diversity of penA Alterations and Subtypes in Neisseria gonorrhoeae Strains from Sydney, Australia, That Are Less Susceptible to Ceftriaxone. Antimicrob. Agents Chemother. 51: 3111-3116 [Abstract] [Full Text]  
• Mangold, K. A., Regner, M., Tajuddin, M., Tajuddin, A. M., Jennings, L., Du, H., Kaul, K. L. (2007). Neisseria Species Identification Assay for the Confirmation of Neisseria gonorrhoeae-Positive Results of the COBAS Amplicor PCR. J. Clin. Microbiol. 45: 1403-1409 [Abstract] [Full Text]  
• Martin, I. M. C., Foreman, E., Hall, V., Nesbitt, A., Forster, G., Ison, C. A. (2007). Non-cultural detection and molecular genotyping of Neisseria gonorrhoeae from a piece of clothing. J Med Microbiol 56: 487-490 [Abstract] [Full Text]  
• Lum, G., Garland, S. M., Tabrizi, S., Harnett, G., Smith, D. W., Sloots, T. P., Whiley, D. M., Tapsall, J. W., Lowe, P., O'Loughlin, P., Bartley, P. B., Vohra, R., Evans, K., White, M. (2006). Supplemental Testing Is Still Required in Australia for Samples Positive for Neisseria gonorrhoeae by Nucleic Acid Detection Tests.. J. Clin. Microbiol. 44: 4292-4294 [Full Text]  
• Hjelmevoll, S. O., Olsen, M. E., Sollid, J. U. E., Haaheim, H., Unemo, M., Skogen, V. (2006). A Fast Real-Time Polymerase Chain Reaction Method for Sensitive and Specific Detection of the Neisseria gonorrhoeae porA Pseudogene. J. Mol. Diagn. 8: 574-581 [Abstract] [Full Text]  
• Whiley, D. M., Tapsall, J. W., Sloots, T. P. (2006). Nucleic Acid Amplification Testing for Neisseria gonorrhoeae: An Ongoing Challenge. J. Mol. Diagn. 8: 3-15 [Abstract] [Full Text]