Post-COVID-19 Pandemic Rebound of Macrolide-Resistant Mycoplasma pneumoniae Infection: A Descriptive Study

Abstract

The rebound characteristics of respiratory infections after lifting pandemic control measures were uncertain. From January to November 2023, patients presenting at a teaching hospital were tested for common respiratory viruses and Mycoplasma pneumoniae using a combination of antigen, nucleic acid amplification, and targeted next-generation sequencing (tNGS) tests. The number and rate of positive tests per month, clinical and microbiological characteristics were analyzed. A rapid rebound of SARS-CoV-2 was followed by a slower rebound of M. pneumoniae, with an interval of 5 months between their peaks. The hospitalization rate was higher, with infections caused by respiratory viruses compared to M. pneumoniae. Though the pediatric hospitalization rate of respiratory viruses (66.1%) was higher than that of M. pneumoniae (34.0%), the 4094 cases of M. pneumoniae within 6 months posed a huge burden on healthcare services. Multivariate analysis revealed that M. pneumoniae-infected adults had more fatigue, comorbidities, and higher serum C-reactive protein, whereas children had a higher incidence of other respiratory pathogens detected by tNGS or pathogen-specific PCR, fever, and were more likely to be female. A total of 85% of M. pneumoniae-positive specimens had mutations detected at the 23rRNA gene, with 99.7% showing A2063G mutation. Days to defervescence were longer in those not treated by effective antibiotics and those requiring a change in antibiotic treatment. A delayed but significant rebound of M. pneumoniae was observed after the complete relaxation of pandemic control measures. No unusual, unexplained, or unresponsive cases of respiratory infections which warrant further investigation were identified.

Keywords: Mycoplasma pneumoniae; macrolide resistance; pandemic; post-COVID-19.

Figure 1

Number of respiratory specimens tested and the positive rate of different respiratory pathogens at HKU-SZH in 2023. Remarks: The respiratory multiplex PCR panel was introduced in June 2023; therefore, only data from June 2023 were available for respiratory viruses. RSV: respiratory syncytial virus.

Figure 2

Days needed to achieve defervescence with different antimicrobial regimens for treatment of Mycoplasma pneumoniae infection. Remarks: A total of 1065 of the 1148 patients achieved defervescence after initiation of different antibiotics, and 15 patients did not receive any drugs with anti-Mycoplasma activity. A total of 9 of the 15 patients did not receive any antibiotics and the other 6 received only beta-lactam antibiotics. Each bar represents the number of days to achieve defervescence with different interventions. The middle line in the box represents the median, the edges of the box represent the interquartile range, the thin black line represents the range, and the circles, squares, and triangles on the plot represent each data point outside the interquartile range of respective groups. MP: Mycoplasma pneumoniae.