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Rapid, sensitive, and specific identification of Ureaplasma urealyticum and Ureaplasma parvum from genitourinary, reproductive, bone and joint, and lower respiratory sources
Ureaplasma urealyticum and Ureaplasma parvum have been associated with a number of clinically significant infections, although their clinical significance may not always be clear as they are part of the normal genital flora. Ureaplasma urealyticum and Ureaplasma parvum have been associated with urethritis and epididymitis. They may cause upper urinary tract infection and they have been associated with infected renal stones. Ureaplasma urealyticum and Ureaplasma parvum may be isolated from amniotic fluid of women with preterm labor, premature rupture of membranes, spontaneous term labor, or chorioamnionitis. They may also cause neonatal infections, including meningoencephalitis and pneumonia. In addition, Ureaplasma urealyticum and Ureaplasma parvum have been reported to cause unusual infections, such as prosthetic joint infection and infections in transplant recipients.
Recently, Ureaplasma urealyticum and Ureaplasma parvum have been found to cause hyperammonemia in lung transplant recipients.(5) In lung transplant recipients with hyperammonemia, the ideal diagnostic specimen is a lower respiratory specimen (eg, bronchoalveolar lavage fluid), although Ureaplasma urealyticum and Ureaplasma parvum may also be detected in blood. Treatment directed against these organisms has resulted in resolution of hyperammonemia.
Culture of Ureaplasma species is laborious, requiring a high degree of technical skill and taking several days. PCR detection is sensitive, specific, and provides same-day results. In addition, PCR allows the differentiation of Ureaplasma urealyticum and Ureaplasma parvum, which is not easily accomplished with culture. PCR assay has replaced conventional culture for Ureaplasma urealyticum and Ureaplasma parvum at Mayo Medical Laboratories due to its speed and equivalent performance to culture.
A positive PCR result for the presence of a specific sequence found within the Ureaplasma urealyticum and Ureaplasma parvum ureC gene indicates the presence of Ureaplasma urealyticum or Ureaplasma parvum DNA in the specimen.
A negative PCR result indicates the absence of detectable Ureaplasma urealyticum and Ureaplasma parvum DNA in the specimen, but does not rule out infection as false-negative results may occur due to inhibition of PCR, sequence variability underlying the primers and/or probes, or the presence of Ureaplasma urealyticum or Ureaplasma parvum in quantities less than the limit of detection of the assay.
Interfering substances may affect the accuracy of this assay; results should always be interpreted in conjunction with clinical and epidemiological findings.
Since Ureaplasma species may be part of the normal flora, results should be interpreted accordingly.
This assay was clinically validated in a blinded manner using 283 archived genitourinary specimens submitted to our laboratory for Ureaplasma culture. Ureaplasma PCR detected 139/144 Ureaplasma culture-positive specimens, as well as 9 that were culture negative (sensitivity, 97%; specificity, 94%). Of the specimens that tested positive for Ureaplasma species, Ureaplasma urealyticum alone was detected in 33, Ureaplasma parvum alone in 109, and both in 6. Discordant results (n=14) were tested by a different PCR assay at the Albany Medical Center, where it was found that 5 of the 9 specimens that were PCR positive/culture negative were PCR positive using the second assay, and all of the 5 specimens that were PCR negative/culture positive were PCR negative using the second assay.(1) The limit of detection of the assay is 100 targets/mcL. A case of prosthetic joint infection caused by Ureaplasma parvum has been diagnosed using the assay (2).
1. Stellrecht KA, Woron AM, Mishrik NG, Venezia RA: Comparison of multiplex PCR assay with culture detection of genital mycoplasmas. J Clin Microbiol 2004;42:1528-1533
2. Farrell JJ, Larson JA, Akeson JW, Lowery KS, et al: Ureaplasma parvum prosthetic joint infection detected by PCR. J Clin Microbiology 2014;52:2248-2250
3. Waites KB, Taylor-Robinson D: Mycoplasma and Ureaplasma. In Manual of Clinical Microbiology. 10th edition. Edited by J Versalovic. ASM Press, Washington, DC, 2011
4. Kenny GE: Genital mycoplasmas: Mycoplasma genitalium, Mycoplasma hominis, and Ureaplasma species. In Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Edited by GL Mandell, et al. Churchill Livingstone, New York, 2008
5. Bharat A, Cunningham SA, Scott Budinger GR, Kreisel D, et al: Disseminated Ureaplasma infection as a cause of fatal hyperammonemia in humans. Sci Transl Med 2015;7(284):284re3