Novel genotypes of Coxiella burnetii identified in isolates from Australian Q fever patients.
Coxiella burnetii, the causative agent of Q fever, was first discovered in Australia in 1937. However, little is known about the strains of C. burnetii present in this country. In this study, six published genotyping methods were applied to 42 isolates from Australian patients with acute (n=39) and chronic (n=3) Q fever. All the isolates contained the plasmid QpRS and lacked the acute disease antigen A (adaA) gene. Two methods of genotyping based on single nucleotide polymorphisms (SNPs) also failed to discriminate between the isolates. However, results from the method based on SNPs within the multi-spacer sequence typing (MST) loci determined a novel MST genotype, with the Australian isolates forming a unique phylogenetic clade. Multi-locus variable number of tandem repeats (VNTR) analysis (MLVA) determined 14 genotypes, all of which were novel compared with those previously identified in strains from other countries. Many of these were single locus variants, differing from each other at just one of the 15 loci tested. Our results show that the Australian isolates exhibit significant diversity from previously characterised strains, but are genetically closely related to each other, supporting a model of evolution by clonal expansion in a geographically isolated location.
Australian Rickettsial Reference Laboratory, University Hospital Geelong, Bellerine Street, Geelong, VIC 3220, Australia; School of Veterinary and Life Science, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia. Electronic address: gvince@barwonhealth.org.au.
Gemma
G
Vincent
Australian Rickettsial Reference Laboratory, University Hospital Geelong, Bellerine Street, Geelong, VIC 3220, Australia; School of Veterinary and Life Science, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia. Electronic address: johns@barwonhealth.org.au.
John
J
Stenos
Microbiology Services Division, Public Health England, Manor Farm Road, Porton Down, Wiltshire SP4 0JG, United Kingdom. Electronic address: jlatham@dstl.gov.uk.
Jennie
J
Latham
School of Veterinary and Life Science, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia. Electronic address: stanley.fenwick@tufts.edu.
Stanley
S
Fenwick
Australian Rickettsial Reference Laboratory, University Hospital Geelong, Bellerine Street, Geelong, VIC 3220, Australia. Electronic address: graves.rickettsia@gmail.com.
Stephen
S
Graves
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000235:genetics; D001315:Australia / Q000453:epidemiology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D016997:Coxiella burnetii / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058889:Molecular Typing / Q000379:methods; D010957:Plasmids / Q000032:analysis; D011778:Q Fever / Q000453:epidemiology / Q000382:microbiology*; D055815:Young Adult
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; C582900:acute disease antigen A, Coxiella burnetii
Australia; Coxiella burnetii; Molecular epidemiology; Molecular typing; Q fever