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Low Ureaplasma Polymerase Chain Reaction Positivity Rate Among Newborns in a Neonatal Intensive Care Unit or Intermediate Special Care Nursery

Madigan, Theresa, MD; Carey, William A., MD; Kaemingk, Bethany D., MD; Patel, Robin, MD

The Pediatric Infectious Disease Journal: May 2019 - Volume 38 - Issue 5 - p e111
doi: 10.1097/INF.0000000000002275
Letters to the Editor
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Division of Pediatric Infectious Diseases, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota

Division of Neonatal Medicine, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota

Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology; and, Division of Infectious Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota

Supported by the Department of Laboratory Medicine and Pathology at Mayo Clinic in Rochester, MN, through a Collaborative Award.

R.P. reports grants from CD Diagnostics, BioFire, Curetis, Merck, Contrafect, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, Allergan, EnBiotix, Contrafect, and The Medicines Company. She is or has been a consultant to Curetis, Specific Technologies, Selux Dx, GenMark Diagnostics, PathoQuest, Heraeus Medical, and Qvella; monies are paid to Mayo Clinic. In addition, she has a patent on Bordetella pertussis/parapertussis polymerase chain reaction issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic and a patent on an antibiofilm substance issued. She receives travel reimbursement from American Society for Microbiology and Infectious Diseases Society of America and an editor’s stipend from American Society for Microbiology and Infectious Diseases Society of America, and honoraria from the National Board of Medical Examiners, Up-to-Date and the Infectious Diseases Board Review Course. All other authors have no conflicts of interest to disclose.

Address for correspondence: Robin Patel, MD, Division of Clinical Microbiology, Mayo Clinic, Rochester, MN 55905. E-mail: patel.robin@mayo.edu.

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To the Editors:

We read with interest the article “Optimum Detection of Ureaplasma in Premature Infants” by Brand et al1 in the December 2018 issue of The Pediatric Infectious Diseases Journal. As pointed out by Brand et al1, the optimal sampling site and timing of specimen collection for Ureaplasma detection in neonates is unclear. Brand et al1 report Ureaplasma culture results subsequently confirmed with polymerase chain reaction (PCR) in infants <34 weeks of gestation. The authors obtained samples from multiple sites on day of life (DOL) 1–2 and 7–10, showing that testing at both time points and from a combination of nasal and oral specimens yields the overall highest positivity. We conducted a similar study of Ureaplasma prevalence in neonates, but instead of using culture, we used direct PCR. This has the advantage over culture of having a faster turnaround time and allowing immediate differentiation between Ureaplasma parvum and Ureaplasma urealyticum. The direct PCR assay we used has been previously shown to have a similar sensitivity (97%) and specificity (94%) to that of culture, based on testing of genitourinary specimens (swabs, urine),2 but has not been directly compared with culture using neonatal samples.

In our study, neonates admitted to the level III/IV neonatal intensive care unit or level II intermediate special care nursery at Mayo Clinic Children’s Center in Rochester, MN, between January 2017 and January 2018 were eligible for inclusion. Infants whose parent or legal guardian gave informed consent for study participation within 72 hours of birth were prospectively enrolled. A throat swab or tracheal aspirate was obtained within the first week of life and directly tested for U. urealyticum and U. parvum using a previously described rapid real-time PCR assay.2,3 Medical records of infants and their mothers were reviewed to gather demographic and clinical information. This study was approved by Mayo Clinic’s Institutional Review Board.

Over the 1-year study period, 148 infants were enrolled. For two infants, no sample could be obtained; the remaining 146 infants were included in the study. The median age at sample collection for Ureaplasma PCR was 38.4 hours (range, 7.6–178.9 hours). Patient characteristics are shown in the Table 1. The positivity rate was just 2%. In comparison, in the study by Brand et al1, the positivity rate was 8% for oral swabs and 15% for tracheal aspirates on DOL 1–2, and 24% for oral swabs and 38% for tracheal aspirates at DOL 7–10, for an overall positivity of 48% (considering all samples combined).

Table 1

Table 1

While the two study populations may not be fully comparable, and positivity rates may vary across centers, our findings support those of Brand et al1 in showing that it is unlikely that a single throat swab or tracheal aspirate collected within the first week of life (tested with culture or direct PCR) is an adequate method to rule out Ureaplasma positivity among neonates. For ideal detection of Ureaplasma species in neonates, sampling of multiple sites and at multiple time points is likely needed.

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ACKNOWLEDGMENTS

The authors thank the Department of Laboratory Medicine and Pathology at Mayo Clinic for generously supporting this study through a Collaborative Award. The authors also thank the Research and Innovation Office for their support with study coordination and data collection. Furthermore, the authors thank the staff in the neonatal units for their help with sample collection and the staff in the clinical microbiology laboratory for performing the polymerase chain reaction testing.

Theresa Madigan, MD

Division of Pediatric Infectious Diseases

Department of Pediatric and Adolescent Medicine

Mayo Clinic

Rochester, Minnesota

William A. Carey, MD

Bethany D. Kaemingk, MD

Division of Neonatal Medicine

Department of Pediatric and Adolescent Medicine

Mayo Clinic

Rochester, Minnesota

Robin Patel, MD

Division of Clinical Microbiology

Department of Laboratory Medicine and Pathology; and

Division of Infectious Diseases

Department of Medicine

Mayo Clinic

Rochester, Minnesota

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REFERENCES

1. Brand MC, Mandy GT, Arora S, et al. Optimum detection of Ureaplasma in premature infants. Pediatr Infect Dis J. 2018;37:1294–1298.
2. Cunningham SA, Mandrekar JN, Rosenblatt JE, et al. Rapid PCR detection of Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum. Int J Bacteriol. 2013;2013:168742.
3. Bharat A, Cunningham SA, Scott Budinger GR, et al. Disseminated Ureaplasma infection as a cause of fatal hyperammonemia in humans. Sci Transl Med. 2015;7:284re3.
4. Jobe AH, Bancalari E. Bronchopulmonary dysplasia. Am J Respir Crit Care Med. 2001;163:1723–1729.
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