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Updated: Jul 4, 2025
Antigen-Capture Enzyme-Linked Immunosorbent Assay for Specific Detection of Mycoplasma pneumoniae
Published on: February 24, 2023
Novel Knowledge of Macrolide Resistance in Mycoplasma pneumoniae by Azithromycin Exposure
Tomohiro Oishi1, Nemu Hattori2, Daisuke Yoshioka1
1Department of Clinical Infectious Diseases, Kawasaki Medical School, 577, Matsushima, Kurashiki 701-0192, Japan.
Abstract:
The rise of macrolide-resistant Mycoplasma pneumoniae (MRMP), marked by point mutations in the 23S rRNA gene, poses a growing global concern since its initial detection in 2001. The prominence of the A2063G mutation during this emergence remains unexplained. This study aimed to clarify the possibility of detecting MRMP from recent clinical macrolide-susceptible M. pneumoniae through exposure to azithromycin (AZM), which has a long half-life and was launched immediately before the first MRMP detection. Six strains isolated from Japanese children in 2019 and reference strain (FH), all belonging to the recent dominant P1 genotype, two, or two subtype, were cultivated in a medium containing slightly higher concentrations than the originated minimum inhibitory concentration (MIC) of AZM and underwent sequencing if they grew. Four out of the seven strains grew after exposure to AZM, and C2617G and C2617A were detected, with no mutation in two strains. After another cultivation and sequencing, two of four strains grew, one was changed from C2617G to A2063G, and the other remained C2617A. The MIC of AZM in A2063G strains was 128 mg/mL; for C2617A, it was 0.0156 mg/mL. This is the first study to detect the strains with A2063G mutation from recent macrolide-susceptible M. pneumoniae using AZM exposure.
Insights
Macrolide-resistant Mycoplasma pneumoniae (MRMP) can emerge from susceptible strains when exposed to azithromycin (AZM). This study demonstrates AZM exposure can induce the A2063G mutation, a key marker of MRMP.
Area of Science:
- Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Macrolide-resistant Mycoplasma pneumoniae (MRMP) emergence, linked to 23S rRNA gene mutations, is a global health concern.
- The specific drivers for the A2063G mutation's prevalence during MRMP emergence are not fully understood.
Purpose of the Study:
- To investigate the potential for macrolide-susceptible M. pneumoniae to develop macrolide resistance through azithromycin (AZM) exposure.
- To explore the induction of specific resistance mutations, such as A2063G, under AZM pressure.
Main Methods:
- Cultivation of M. pneumoniae strains (including a reference strain and six clinical isolates from Japan) in media with sub-inhibitory AZM concentrations.
- DNA sequencing of bacterial isolates that demonstrated growth under AZM pressure to identify mutations in the 23S rRNA gene.
- Determination of minimum inhibitory concentrations (MICs) for AZM against identified resistant strains.
Main Results:
- Four of seven M. pneumoniae strains grew after AZM exposure, revealing C2617G and C2617A mutations.
- Subsequent cultivation led to one strain converting from C2617G to the A2063G mutation.
- The A2063G mutation conferred high-level AZM resistance (MIC = 128 mg/mL), while C2617A showed susceptibility (MIC = 0.0156 mg/mL).
Conclusions:
- This study provides the first evidence of inducing the A2063G mutation in macrolide-susceptible M. pneumoniae through AZM exposure.
- The findings suggest that AZM pressure may play a role in the emergence of specific macrolide resistance mechanisms in M. pneumoniae.
- Understanding these resistance pathways is crucial for managing M. pneumoniae infections and guiding antimicrobial stewardship.
