The Swedish new variant of Chlamydia trachomatis: genome sequence, morphology, cell tropism and phenotypic characterization.
Chlamydia trachomatis is a major cause of bacterial sexually transmitted infections worldwide. In 2006, a new variant of C. trachomatis (nvCT), carrying a 377 bp deletion within the plasmid, was reported in Sweden. This deletion included the targets used by the commercial diagnostic systems from Roche and Abbott. The nvCT is clonal (serovar/genovar E) and it spread rapidly in Sweden, undiagnosed by these systems. The degree of spread may also indicate an increased biological fitness of nvCT. The aims of this study were to describe the genome of nvCT, to compare the nvCT genome to all available C. trachomatis genome sequences and to investigate the biological properties of nvCT. An early nvCT isolate (Sweden2) was analysed by genome sequencing, growth kinetics, microscopy, cell tropism assay and antimicrobial susceptibility testing. It was compared with relevant C. trachomatis isolates, including a similar serovar E C. trachomatis wild-type strain that circulated in Sweden prior to the initially undetected expansion of nvCT. The nvCT genome does not contain any major genetic polymorphisms - the genes for central metabolism, development cycle and virulence are conserved - or phenotypic characteristics that indicate any altered biological fitness. This is supported by the observations that the nvCT and wild-type C. trachomatis infections are very similar in terms of epidemiological distribution, and that differences in clinical signs are only described, in one study, in women. In conclusion, the nvCT does not appear to have any altered biological fitness. Therefore, the rapid transmission of nvCT in Sweden was due to the strong diagnostic selective advantage and its introduction into a high-frequency transmitting population.
Unemo
Magnus
M
National Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Clinical Microbiology, örebro University Hospital, örebro, Sweden.
Seth-Smith
Helena M B
HMB
Pathogen Genomics, The Wellcome Trust Sanger Institute, Cambridgeshire, UK.
Cutcliffe
Lesley T
LT
Molecular Microbiology Group, University Medical School, Southampton General Hospital, Southampton, UK.
Skilton
Rachel J
RJ
Molecular Microbiology Group, University Medical School, Southampton General Hospital, Southampton, UK.
Barlow
David
D
Molecular Microbiology Group, University Medical School, Southampton General Hospital, Southampton, UK.
Goulding
David
D
Microbial Pathogenesis Electron Microscope Facility, The Wellcome Trust Sanger Institute, Cambridge, UK.
Persson
Kenneth
K
Department of Clinical Microbiology, Malmö University Hospital, Malmö, Sweden.
Harris
Simon R
SR
Pathogen Genomics, The Wellcome Trust Sanger Institute, Cambridgeshire, UK.
Kelly
Anne
A
National Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Clinical Microbiology, örebro University Hospital, örebro, Sweden.
Bjartling
Carina
C
Department of Obstetrics and Gynaecology, Malmö University Hospital, Malmö, Sweden.
Fredlund
Hans
H
National Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Clinical Microbiology, örebro University Hospital, örebro, Sweden.
Olcén
Per
P
National Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Clinical Microbiology, örebro University Hospital, örebro, Sweden.
Thomson
Nicholas R
NR
Pathogen Genomics, The Wellcome Trust Sanger Institute, Cambridgeshire, UK.
Clarke
Ian N
IN
Molecular Microbiology Group, University Medical School, Southampton General Hospital, Southampton, UK.
D001483:Base Sequence; D002690:Chlamydia Infections / Q000175:diagnosis / Q000453:epidemiology / Q000635:transmission; D002692:Chlamydia trachomatis / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification / Q000648:ultrastructure; D003951:Diagnostic Errors; D016680:Genome, Bacterial; D006801:Humans; D002479:Inclusion Bodies; D008297:Male; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids; D013045:Species Specificity; D013548:Sweden / Q000453:epidemiology; D018523:Tropism