title: Two case reports: Whole genome sequencing of two clinical macrolide-resistant Mycoplasma pneumoniae isolates with different responses to azithromycin.
abstract: BACKGROUND
  Cases of macrolide-resistant Mycoplasma pneumoniae have increased rapidly since 2000, especially in Asia. Patients infected with macrolide-resistant M pneumoniae usually present with severe M pneumoniae pneumonia. The aim of this study was to identify indicators for whether children at an early stage of M pneumoniae infection develop mild or severe pneumonia.
  
  
  METHODS
  Herein, we retrospectively reviewed 2 pediatric cases caused by macrolide-resistant M pneumoniae, but with markedly different severity of pneumonia. First, we compared the clinical courses of the patients, then isolated the pathogens and tested their response to macrolides, then finally, carried out whole genome sequencing of these isolates. Despite the difference in clinical presentation of the infection, both isolates exhibited a high level of resistance to macrolide antibiotics. Analysis of clinical data showed that the erythrocyte sedimentation rate in blood samples of the patients in the early stages of disease varied greatly. Genome sequence analysis revealed single nucleotide polymorphisms mainly focused on adhesin P1, which is involved in the pathogenicity of M pneumoniae.
  
  
  CONCLUSIONS
  The differences of erythrocyte sedimentation rate in the early stage of M pneumoniae pneumonia and mutations in P1 protein may help us to distinguish between severe or mild disease after infection with macrolide-resistant M pneumoniae. These findings could lead to the development of screening assays that will allow us to distinguish severe or mild M pneumoniae pneumonia early.
authors.affiliation: Department of Bacteriology, Capital Institute of Pediatrics Microbial Genome Research Center, CAS Key Lab of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shaoli
authors.initials: S
authors.lastname: Li
authors.forename: Hongmei
authors.initials: H
authors.lastname: Sun
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.forename: Yanling
authors.initials: Y
authors.lastname: Feng
authors.forename: Hanqing
authors.initials: H
authors.lastname: Zhao
authors.forename: Guanhua
authors.initials: G
authors.lastname: Xue
authors.forename: Chao
authors.initials: C
authors.lastname: Yan
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D017963:Azithromycin / Q000627:therapeutic use*; D002648:Child; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D006801:Humans; D018942:Macrolides / Q000627:therapeutic use*; D008297:Male; D009177:Mycoplasma pneumoniae / Q000235:genetics*; D011019:Pneumonia, Mycoplasma / Q000188:drug therapy / Q000382:microbiology*; D020641:Polymorphism, Single Nucleotide; D012189:Retrospective Studies; D017422:Sequence Analysis, DNA
chemical_list: D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents; D018942:Macrolides; C035471:adhesin, Mycoplasma pneumoniae; D017963:Azithromycin