Volume 32, Number 1—January 2026
Research Letter
Localized Outbreak of Macrolide-Resistant Pertussis in Infants, Japan, March–May 2025
Takafumi Obara
, Kyoko Kano, Takashi Yorifuji, Kohei Tsukahara, Naoki Yogo, Yuichiro Muto, Tetsuya Yumoto, Hiromichi Naito, Atsunori Nakao, and Katsuki Hirai
, Kyoko Kano, Takashi Yorifuji, Kohei Tsukahara, Naoki Yogo, Yuichiro Muto, Tetsuya Yumoto, Hiromichi Naito, Atsunori Nakao, and Katsuki Hirai
Table
Demographic information for 9 infants diagnosed with pertussis and admitted to the pediatric intensive care unit, Kumamoto, Japan, March–May 2025*
| Variable |
Value |
|---|---|
| Patient characteristics | |
| Median age, d (IQR) | 44 (33–50) |
| Sex | |
| M | 3 (33.3) |
| F | 6 (66.7) |
| Median weight, g (IQR) | 4,000 (3,600–4,266) |
| Median birthweight, g (IQR) | 3,032 (2,560–3,190) |
| Median gestational age at birth, wk (IQR) | 38 (37–39) |
| Underlying condition | 0 (0.0) |
| Unvaccinated |
9 (100) |
| Sick contact in family | 9 (100) |
| Age group of symptomatic family members | |
| Siblings age 1–6 y | 1 (11.1) |
| Siblings age 7–12 y | 5 (55.6) |
| Parents age ≥18 y |
3 (33.3) |
| Azithromycin use before PICU admission | 6 (66.7) |
| MRBP confirmed† |
6 (66.7) |
| Ventilator management | 9 (100) |
| Nitric oxide therapy | 1 (11.1) |
| Prone positioning | 4 (44.4) |
| Rocuronium | 8 (88.9) |
| Vasopressor |
3 (33.3) |
| TMP/SMX use | 6 (66.7) |
| Leukapheresis | 3 (33.3) |
| Pulmonary hypertension diagnosis |
2 (22.2) |
| Clinical course and outcomes | |
| Median days from symptom onset to PICU admission (IQR) | 7 (7–12) |
| Median days from PICU admission to intubation days, d (IQR) | 1 (0–1) |
| Median days of ventilator use, d (IQR) | 8 (7–9) |
| Median PICU admission, d (IQR) | 15 (14–19) |
| Median hospitalization, d (IQR) | 23 (19–24) |
*Values are no. (%) except as indicated. IQR, interquartile range; MRBP, macrolide-resistant Bordetella pertussis; PICU, pediatric intensive care unit; TMP/SMX, trimethoprim/sulfamethoxazole. †Of 6 infants tested (MRBP undetermined in 3 infants).
Page created: January 16, 2026
Page updated: January 29, 2026
Page reviewed: January 29, 2026
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.