JOURNAL OF BACTERIOLOGY AND VIROLOGY ISSN:1598-2467(Print) 2093-0429(Online)

Following the COVID-19 pandemic, the epidemiology of respiratory infectious diseases has changed substantially, with a marked resurgence of pertussis among children and adolescents in Korea in 2024. Although current molecular diagnostic methods for pertussis, based on detection of IS481, provides high sensitivity, they have limitations in differentiating closely related Bordetella species and in identifying concomitant bacterial respiratory pathogens. Moreover, region-specific surveillance data for bacterial respiratory infections remain limited compared with those for viral respiratory infections. From July–December 2024, in total, 607 respiratory specimens were collected from pertussis-positive patients under aged < 19 years at private medical institutions in Busan. These comprised 602 nasopharyngeal swabs and five sputum samples. Using nucleic acid amplification methods, six major bacterial respiratory pathogens, along with the pertussis-related species B. holmesii, were investigated. Age group–specific distributions, pathogen detection patterns, and co-detection profiles were evaluated. Among the 607 specimens, at least one bacterial respiratory pathogen was detected in 366 cases (60.3%). B. pertussis was the most frequently detected pathogen (205 cases), followed by Haemophilus influenzae (119 cases), B. holmesii (79 cases), Streptococcus pneumoniae (73 cases), and Mycoplasma pneumoniae (55 cases). Pathogen detection was most prominent in school-aged children and adolescents. Co-detection of two or more bacterial pathogens was identified in 142 cases (38.8%), including dual detections in 115 cases, triple co-detections in 25 cases, and quadruple co-detections in two cases. Notably, co-detections involving B. pertussis and M. pneumoniae was relatively common. This study provides a comprehensive characterization of the distribution and co-detection patterns of bacterial respiratory pathogens in pertussis-positive specimens from children and adolescents during the 2024 pertussis resurgence in Busan. These findings underscore the importance of considering concomitant bacterial infections in patients with pertussis-like symptoms and may serve as baseline data for strengthening region-specific surveillance and the development of multi-pathogen–oriented diagnostic and treatment strategies for bacterial respiratory infections.