170. Detection of Bordetella holmesii, and Relevance of Age, during an Outbreak of Pertussis in Central Ohio
Session: Oral Abstract Session: Pediatric Pneumonia
Friday, October 21, 2011: 11:30 AM
Room: 156ABC
Background:  A significant increase in the laboratory diagnosis of pertussis was noted in central Ohio during 2010 based on PCR testing of nasopharyngeal (NP) swab specimens for the repetitive sequence IS481 found in Bordetella pertussis (Bp).  Bordetella holmesii (Bh), although rarely implicated as a respiratory pathogen, shares this sequence and may result in falsely positive PCR results for pertussis when IS481-directed PCR is used alone.  Although not standard laboratory practice, specific PCR assays can be used to explore the relative occurrence of Bp and Bh in IS481-positive patients.

Methods:  Available IS481 positive NP specimens tested in the Nationwide Children’s Hospital microbiology lab were further analyzed with PCR assays specific for Bp (pertussis toxin promoter sequence) and Bh (IS1001-like sequence).  Culture was also attempted on selected specimens.  Patients were grouped based on PCR results (IS481/pertussis toxin positive, IS481/IS1001-like positive, and IS481 only positive) and compared on age and gender.

Results:  Of 523 IS481 positive specimens, 213 (41%) were confirmed positive for Bp, 79 (15%) for Bh, and 6 (1%) for both Bp and Bh.  225 samples (43%) were negative on both specific PCR assays.  75% of those 1-4 years were IS481 only positive.  Cultures positive for either Bp or Bh corresponded 100% with results of PCR assays.  Patients confirmed as Bh were older (mean age 12 years) than patients with Bp (mean 8 years), who were older than IS481 only positive patients (mean 6 years).  In the ≥15 years group, 53% of patients were confirmed as Bh, while only 16% were confirmed as Bp.  35% of patients confirmed as Bh were ≥15 years, while only 4% of those confirmed as Bp were in this age range.

Conclusion:  These data suggest a potentially significant role for Bh in respiratory disease, particularly in adolescents presenting with symptoms of pertussis.  Testing strategies for pertussis need to be re-considered as we better understand the epidemiology and clinical characteristics of infection with Bh.  The inability to confirm 43% of IS481 positive specimens primarily reflects the higher sensitivity of PCR targeting a repetitive sequence (IS481).  Explanation of the large percentage of non-confirmed IS481 positives in the 1-4 year age group remains unclear.


Subject Category: P. Pediatric and perinatal infections

Kevin Spicer, MD, PhD, MPH1,2, Douglas Salamon, CLSpMB3, Carol Cummins, BS3, Amy Leber, PhD3 and Mario Marcon, PhD2,3, (1)Infectious Diseases, Nationwide Children's Hospital, Columbus, OH, (2)The Ohio State University, Columbus, OH, (3)Department of Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH

Disclosures:

K. Spicer, None

D. Salamon, None

C. Cummins, None

A. Leber, None

M. Marcon, None

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