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Antibiotic Resistance and Azithromycin Resistance Mechanism of Legionella pneumophila Serogroup 1 in China.

ABSTRACT: Legionnaires' disease, caused by Legionella pneumophila, has been treated primarily with antibiotics. However, few reports have been published on antibiotic-resistant Legionella in China. Our aim was to determine the azithromycin resistance mechanism of L. pneumophila serogroup 1 in China. The sensitivities of 149 L. pneumophila serogroup 1 strains, isolated from clinical cases or environmental water in China from 2002 to 2016, to five antibiotics, including erythromycin, azithromycin, levofloxacin, moxifloxacin, and rifampin, were evaluated. The mechanisms of the resistance of L. pneumophila serogroup 1 to azithromycin were studied. The expression levels of efflux pump gene lpeAB and the MIC of azithromycin-resistant strains in the presence and absence of the efflux pump inhibitor carbonyl cyanide-chlorophenylhydrazone (CCCP) were determined. All 149 strains were sensitive to erythromycin, levofloxacin, moxifloxacin, and rifampin, among which 25 of the strains exhibited azithromycin resistance. These 25 strains, including strains of sequence type 1 (ST1), ST144, ST150, ST154, and ST629, were screened. Expression of lpeAB was responsible for the reduced azithromycin susceptibility in all 25 of these strains. The phenotypes of 25 strains with virulence were linked by evaluating the intracellular growth ability in mouse macrophage J774 cells. Among the 25 strains, 60% were more virulent than the ATCC 33152 reference strain. The results determined in our study represent data supporting the further study of the antibiotic sensitivity of L. pneumophila strains in China.

SUBMITTER: Jia X

PROVIDER: S-EPMC6761501 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Antibiotic Resistance and Azithromycin Resistance Mechanism of Legionella pneumophila Serogroup 1 in China.

Jia Xueyang X Ren Hongyu H Nie Xudong X Li Yinan Y Li Jianguo J Qin Tian T

Antimicrobial agents and chemotherapy 20190923 10

Legionnaires' disease, caused by Legionella pneumophila, has been treated primarily with antibiotics. However, few reports have been published on antibiotic-resistant Legionella in China. Our aim was to determine the azithromycin resistance mechanism of L. pneumophila serogroup 1 in China. The sensitivities of 149 L. pneumophila serogroup 1 strains, isolated from clinical cases or environmental water in China from 2002 to 2016, to five antibiotics, including erythromy ...[more]

PMID: 31405864

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Project description:The Legionella pneumophila TF3/1 mutant of the Corby strain, which possesses a point mutation in the active site of the O-acetyltransferase, synthesized the polysaccharide chain with a reduced degree of substitution with O-acetyl groups. The mutant did not produce a high-molecular-weight lipopolysaccharide (LPS) fraction above 12 kDa. The disturbances in LPS synthesis have an effect on the composition of other macromolecules (lipids and proteins), as indicated by differences in the infrared absorption spectra between the L. pneumophila Corby strain and its TF3/1 mutant. The wild-type strain contained less N+-CH3 and C-N groups as well as more CH3 groups than the mutant. The fatty acid composition showed that the wild type strain synthesized more branched acyl residues (a15:0, i16:0, and a17:0), a less unsaturated acid (16:1), and a straight-chain acid (18:0) than the mutant. The mutant synthesized approximately twice more a long-chain fatty acid (20:0) than the wild type. The main differences in the phospholipids between both strains were found in the classes of phosphatidylcholines and phosphatidylglycerols (PG). Substantial differences in the cell surface topography of these bacteria and their nanomechanical properties were shown by atomic force microscopy (AFM). The wild type strain had no undulated surface and produced numerous vesicles. In the case of the mutant type, the vesicles were not numerous, but there were grooves on the cell surface. The average roughness of the cell surface of the mutant was approximately twofold higher than in the wild-type strain. In turn, the wild-type strain exhibited much better adhesive properties than the mutant. The kinetic study of the interaction between the L. pneumophila strains and Acanthamoeba castellanii monitored by Förster resonance energy transfer revealed a pronounced difference, i.e., almost instantaneous and highly efficient binding of the L. pneumophila Corby strain to the amoeba surface, followed by penetration into the amoeba cells. This process was clearly not as efficient in the case of the mutant. The results point to LPS and, in particular, to the length of the polysaccharide fraction as an important L. pneumophila determinant involved in the process of adhesion to the host cell.

Dataset Information

Antibiotic Resistance and Azithromycin Resistance Mechanism of Legionella pneumophila Serogroup 1 in China.

Publications

Antibiotic Resistance and Azithromycin Resistance Mechanism of Legionella pneumophila Serogroup 1 in China.

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