A pertussis outbreak was studied in a primary school in Xi’an, China, in March 2016. The school consisted of 536 pupils 6–12 years of age who were divided into 12 classes of 6 grades (2 classes for each grade). The identified index case was an 11-year-old girl at class 2 of grade 5.
Interview was conducted and nasopharyngeal swabs were taken from all pupils (N = 94) in the 2 classes of grade 5. Nasopharyngeal swabs were tested by both culture and polymerase chain reaction (PCR).
Four culture- and 17 PCR-positive cases were identified in 94 pupils. Infection rate was significantly higher in class 2 compared with that in class 1 [37.0% (17/46) vs. 14.6% (7/48), χ2 = 4.26, P < 0.05]. All Bordetella pertussis isolates were macrolide-resistant, harbored prn1/ptxP1/fim3-1 as previously reported and belonged to multilocus variable tandem repeat analysis type MLVA 195. Of the 17 DNAs positive for diagnostic PCR, 12 were also positive for 23S ribosomal RNA PCR. All the 12 DNAs had the A2047G mutation of 23S rRNA gene of B. pertussis.
This study described a pertussis outbreak caused by macrolide-resistant B. pertussis in a primary school and indicated that close contact of index case causes the bacterial transmission.
From the *Department of Infectious Diseases, Xi’an Children Hospital, Xi’an, China
†Department of Vaccine Preventable Diseases, Xi’an Center for Disease Control and Prevention, Xi’an, China
‡Department of Medical Microbiology, Capital Medical University, Beijing, China
§Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
Accepted for publication July 29, 2017.
This study is supported by National Nature Science Foundation of China (No.81602902).
The authors have no conflicts of interest to disclose.
X.L. and Z.W. contributed equally to this work. Y.L. and Q.H. contributed to the study design, data analysis, and writing. X.L. and Z.W. carried out the experimental work; data analysis and interpretation; and preparation of the manuscript. J.Z., F.L. and Y.L. contributed to acquisition of samples. H.L. carried out the interviews and statistical analysis. All authors reviewed and approved the final manuscript as submitted.
Address for correspondence: Yarong Li, MM. Department of Infectious Diseases, Xi’an Children Hospital, Xi’an, China. E-mail: email@example.com or Qiushui He, MC, PHD, Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland. E-mail: Qiushui.He@utu.fi.