title: Population dynamics of Neisseria gonorrhoeae in Shanghai, China: a comparative study.
abstract: BACKGROUND
  Gonorrhea is a major sexually transmitted disease (STD) in many countries worldwide. The emergence of fluoroquinolone resistance has complicated efforts to control and treat this disease. We report the first study of the evolutionary processes acting on transmission dynamics of a resistant gonococcal population from Shanghai, China. We compare these findings with our previous study of the evolution of a fluoroquinolone sensitive gonococcal population from Baltimore, MD.
  
  
  METHODS
  Ninety six gonococcal samples were collected from male patients in Shanghai, China. All samples were fluoroquinolone resistant. Seven MLST housekeeping genes, two fluoroquinolone resistance genes (gyrA and parC) and the porB gene were sequenced and subjected to population genetic and evolutionary analyses. We estimated genetic diversity, recombination, growth, and selective pressure. The evolutionary history and population dynamics of the Shanghai population were also inferred and compared with that observed in a fluoroquinolone sensitive gonococcal population from Baltimore.
  
  
  RESULTS
  For both populations, mutation plays a larger role than recombination in the evolution of the porB gene, whereas the latter seems to be the main force driving the evolution of housekeeping and fluoroquinolone resistance genes. In both populations there was evidence for positively selected sites in all genes analyzed. The phylogenetic analyses showed no temporal clustering in the Shanghai gonococcal population, nor did we detect shared allelic profiles between the Shanghai and the Baltimore populations. Past population dynamics of gonococcal strains from Shanghai showed a rising relative effective population size (Ne) in MLST genes with a declining relative Ne for gyrA and parC, whereas among sensitive strains from Baltimore we previously observed concordance among these genes. In both Shanghai and Baltimore, the past population dynamics of gonococcal strains tracked changes in the prevalence of gonorrhea.
  
  
  CONCLUSIONS
  Our study illustrates both similarities and differences in the evolutionary processes acting on gonococcal populations in different geographic areas. An explanation of this pattern that may apply in China is the continued use of quinolone antibiotics despite widespread resistance. Population genetic analysis of gonococcal strains in conjunction with epidemiological surveillance may provide insights into the epidemic behavior of antibiotic resistant strains and help to design control measures.
authors.affiliation: Division of Epidemiology and Disease Control, University of Texas, Health Science Center at Houston, School of Public Health, Brownsville Regional Campus, Brownsville, TX, USA. Loubna.Tazi@uth.tmc.edu
authors.forename: Loubna
authors.initials: L
authors.lastname: Tazi
authors.forename: Marcos
authors.initials: M
authors.lastname: Pérez-Losada
authors.forename: Weiming
authors.initials: W
authors.lastname: Gu
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Lin
authors.initials: L
authors.lastname: Xue
authors.forename: Keith A
authors.initials: KA
authors.lastname: Crandall
authors.forename: Raphael P
authors.initials: RP
authors.lastname: Viscidi
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D015142:Baltimore / Q000453:epidemiology; D001499:Bayes Theorem; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D019143:Evolution, Molecular; D024841:Fluoroquinolones / Q000627:therapeutic use; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D006069:Gonorrhea / Q000453:epidemiology*; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation; D009344:Neisseria gonorrhoeae / Q000145:classification* / Q000187:drug effects / Q000235:genetics; D010802:Phylogeny; D011157:Population Dynamics; D011995:Recombination, Genetic; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones