Antibiotic resistance and genetic characteristics of Legionella pneumophila isolated from artificial water environment in Zhongshan from 2012 to 2024
- VernacularTitle:2012—2024年中山市人工水环境嗜肺军团菌耐药性及基因特征
- Author:
Qiming LIU
1
;
Zhanhong YUAN
1
;
Canquan WU
1
;
Qilin QIU
1
;
Yuekang ZHENG
1
Author Information
- Publication Type:Investigation
- Keywords: Legionella pneumophila; antimicrobial susceptibility testing; whole genome sequencing; antibiotic resistance gene; phylogenetic analysis
- From: Journal of Environmental and Occupational Medicine 2025;42(12):1497-1503
- CountryChina
- Language:Chinese
- Abstract: Background There is currently limited research on the antibiotic resistance of Legionella pneumophila in China. Establishing analytical methods for antibiotic resistance phenotypes and resistance genes of Legionella pneumophila in artificial water environment is of great significance. Objective To investigate the antibiotic resistance characteristics of Legionella pneumophila isolated from artificial water environment in Zhongshan, and to provide a scientific basis for the prevention and control of Legionella infection. Methods A total of 295 strains of Legionella pneumophila isolated from central air conditioning systems and hot water systems in Zhongshan from 2012 to 2024 were collected. The minimum inhibitory concentrations (MIC) of antimicrobial agents against the strains were determined using the E-test method. Whole genome sequencing combined with bioinformatics techniques was used to analyze the antibiotic resistance genes of 16 strains of Legionella pneumophila. The phylogenetic evolutionary relationships between these strains and clonal strains from different sources worldwide were analyzed based on whole genome single nucleotide polymorphisms (wgSNPs). Results The antimicrobial susceptibility testing results showed that the highest resistance rate of Legionella pneumophila was to erythromycin (ERY) (56.9%), followed by azithromycin (AZM) (27.1%) and levofloxacin (LEV) (12.2%). The antibiotic resistance rates to rifampicin (RIF) and cefotaxime (CTX) were low, and the strains were fully susceptible to clarithromycin (CLA), ciprofloxacin (CIP), and doxycycline (DOX). Compared to the isolates from the hot water systems, those from the central air conditioning systems exhibited higher resistance rates to ERY (70.9% vs. 28.1%) and AZM (34.2% vs. 12.5%), and the differences were statistically significant (χ2=48.226, P<0.001; χ2=15.388, P<0.001). The MIC values of Lp1 isolates for four antibiotics (AZM, CLA, DOX, and CTX) were significantly higher than those of Lp2-14 isolates (Z=−3.490, P <0.001; Z=−3.035, P <0.05; Z=−2.662, P<0.05; Z=−2.973, P <0.05). The MIC values of Lp2−14 isolates for RIF were significantly higher than those of Lp1 isolates (Z=−3.190, P<0.05). The strains isolated from 2019–2024 exhibited higher MIC values for both CLA and DOX than those isolated from 2012–2018 (Z=−4.847, P <0.001; Z=−6.057, P <0.001). Whole genome sequencing analysis showed that the 16 strains of Legionella pneumophila carried antibiotic resistance genes for aminoglycosides, macrolides, cephalosporins, and penicillins. The phylogenetic analysis showed that Legionella pneumophila in this region exhibited high genetic diversity and was consistent with the epidemic trends of strains from other regions worldwide. Conclusion The isolates of Legionella pneumophila in this study are highly susceptible to most antimicrobial agents. However, the antibiotic resistance should not be ignored, and continuous monitoring of antibiotic resistance is necessary.
