Dynamics of Azithromycin Resistance in Pediatric Haemophilus Influenzae Isolates in Wuhan (2015–2024)
Year: 2026
Type: article
Abstract: To investigate the 10-year dynamics of azithromycin resistance in Haemophilus influenzae isolates from pediatric inpatients in Wuhan, and to assess the temporal association with major public health events, including COVID-19 containment and the 2023 Mycoplasma pneumoniae epidemic. A total of 815 non-duplicate H. influenzae isolates were collected from pediatric inpatients with respiratory tract infections (2015–2024). Azithromycin susceptibility was determined by CLSI-recommended disk diffusion. Annual resistance rates, mean inhibition zone diameters, and isolate volumes were analyzed. Statistical methods included the Jonckheere–Terpstra trend test, χ 2 tests, linear regression, and segmented regression with pre-specified calendar breakpoints at 2020 and 2022; an exploratory Spearman correlation with annual MRMP positivity (2018–2024) was also performed. The azithromycin resistance rate increased significantly from 20.0% in 2015 to 61.7% in 2024 (Z = −6.837, P < 0.001). From 2020 to 2024, susceptibility declined sharply from 69.7% to 38.3%, averaging a 7.85% annual decrease. A transient, non-significant improvement in susceptibility was observed in 2020 ( P = 0.518), temporally coincident with the initial COVID-19 containment period. In 2023, susceptibility dropped by 20.57% ( P = 0.004), the largest single-year decline, with resistance surpassing 50% for the first time. This resistance surge paralleled a 57.7% increase in isolate volume and a city-wide MRMP epidemic with high macrolide resistance reported. Mean inhibition zone diameter strongly correlated with susceptibility (R 2 = 0.90, P < 0.001), decreasing to 11.91 mm in 2024, near the CLSI resistance breakpoint. In segmented regression with pre-specified breakpoints at 2020 and 2022, we observed a non-significant level drop at 2020 (−0.484 log-odds; p = 0.270) and a non-significant post-2022 slope increase (Δslope +0.777 log-odds/year; p = 0.126). In a complementary three-phase model, the 2023–2024 slope was significant (+1.065 log-odds/year; p < 0.001). Early-2020 COVID-19–related containment may have coincided with a temporary slowdown in azithromycin resistance, whereas the 2023 MRMP epidemic was associated with a marked surge—consistent with a level drop at 2020 and a non-significant post-2022 slope increase in segmented regression. Inhibition zone diameter appears to provide an early phenotypic warning of resistance shifts. These findings support reassessing empirical treatment choices and strengthening regional resistance surveillance. • Longitudinal analysis of azithromycin resistance in Haemophilus influenzae isolates from pediatric inpatients over a 10-year period (2015–2024) at Wuhan Fourth Hospital. • Sharp increase in azithromycin resistance observed in 2023, coinciding with a Mycoplasma pneumoniae outbreak and increased macrolide usage. • Transient improvement in azithromycin susceptibility in 2020, likely influenced by COVID-19 containment measures and decreased hospital admissions. • Strong correlation (R 2 = 0.90) between inhibition zone diameter and azithromycin susceptibility, offering a potential early warning marker for resistance. • Findings emphasize the urgent need for revised empirical treatment guidelines and enhanced regional resistance monitoring to address growing macrolide resistance.
Source: Infection Genetics and Evolution
Authors: Xing Zhang, HongYan Chen, Jing Xiong
Institution: Wuhan Puai Hospital
Language: English
Subfield: Molecular Medicine
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,730
OpenAlex ID: W7125400085