as a national reference center for q fever , our center receives samples from france and other regions for serologic , molecular , histologic , and immunohistochemical analyses as described ( 57 ) .
in 2012 , we received a cardiac valve sample from a patient in cayenne with q fever endocarditis who had undergone surgery in martinique . in the same year , we collected 4 heparinized blood samples from patients with acute q fever from cayenne that were collected before initiation of antimicrobial drug treatment .
serologic titers of igg1 increased to 51,200 in this patient , and results of quantitative pcr ( qpcr ) and immunohistochemical analyses of the valvular sample were positive for c. burnetii ( figure 1 ) .
the other 4 patients ( 2 men and 2 women ) had fever and acute pneumonia , and 2 of them also had increased transaminase levels .
the heparinized blood samples were tested by using a specific qpcr ; samples from only 1 patient were positive for c. burnetii .
immunohistochemical detection of coxiella burnetii in resected cardiac valve of a 60-year - old man with q fever endocarditis , cayenne , french guiana .
we successfully cultured c. burnetii from the valvular sample after incubation for 16 days and from 3 blood samples after incubation for 25 , 32 , and 32 days .
paradoxically , the only blood sample that was positive by qpcr was negative by culture .
spacers cox 51 and cox 20 were the most discriminating spacers in identifying this genotype , and the 3 isolates from the blood cultures were also identified by these 2 spacers as genotype 17 ( figure 2 ) .
this genotype had been identified in our laboratory only once , in 2000 in an aortic valve of a 40-year - old french man who had undergone surgery in france , had q fever endocarditis , and was co - infected with streptococcus oralis .
retrospectively , we found that patient had lived in cayenne for years before his diagnosis with q fever endocarditis .
therefore , all genotype 17 isolates were obtained from who lived or had lived in cayenne , making it unique to this area .
we determined the antimicrobial drug susceptibilities of these isolates , and the mic of doxycycline was 0.25 g / ml for all isolates ( 10 ) .
phylogenetic diversity of 34 genotypes of coxiella burnetii identified by using multispacer sequence typing ( mst ) .
scale bar indicates nucleotide substitutions per site . for the past 10 years , routine cell culture for c. burnetii has been performed in our laboratory .
we found that the proportion of isolates obtained from blood samples of patients with acute q fever was higher for patients from cayenne than for patients from metropolitan france .
we obtained 3 isolates from 5 blood samples from untreated patients in cayenne and 3 isolates from 65 samples from patients in metropolitan france ( p = 0.003 , by fisher exact test ) .
however , we did not find any difference with respect to the culture delay between patients from the 2 locations .
our work shows that genotype 17 , a unique genotype , is circulating in cayenne .
this genotype is related to genotypes that harbor the qph1 plasmid , which causes the most severe clinical forms of acute q fever in experimental animal models ( 11,12 ) .
only bacteria from this group and bacteria containing the qpdv plasmid have been found in cases of human acute q fever ( 9,13 ) .
we believe that severity of q fever infection is related to the strain of c. burnetii circulating in cayenne . because the population in french guiana is a large diversity of creole , amerindian , maroon , caucasian , and asian persons ( 14 ) , we excluded the hypothesis that genetic susceptibility of patients from cayenne to c. burnetii infection might be related to severity of the disease .
we observed a higher rate of strain isolation from the blood of patients from cayenne than from the blood of patients from metropolitan france .
this difference may be related to a higher bacterial load in blood or a greater ability of the bacteria to grow on cell cultures .
this second hypothesis seems more likely because even if the observed delay for the first culture was the same for genotype 17 and other genotypes , the strain from cayenne was isolated more frequently in the cell line that we used ( hel cells ) than other strains of c. burnetii from france . in addition , we did not find a higher number of dna copies in the blood of patients from cayenne , and qpcr results were not correlated with culture results . c. burnetii isolates from cayenne were susceptible to antimicrobial drugs , particularly doxycycline .
these isolates cause acute pneumonia and endocarditis . among the 34 genotypes identified in our study by multispacer
a larger biodiversity of strains has been observed in samples from patients in metropolitan france ( 9 ) , where 21 genotypes circulate ( figure 2 ) .
in contrast , during the recent q fever outbreak in the netherlands , it appears that a single strain ( genotype 33 ) was responsible for the epidemic ( 15 ) .
we believe that there has been an epidemic developing in cayenne since 1996 that is caused primarily , if not solely , by a single strain that has circulated since at least 2000 , whose reservoir is unknown ( 1,2 ) . in conclusion ,
c. burnetii genotype 17 is circulating in french guiana and causing acute infections and endocarditis .
this strain is epidemic and most likely causes more acute infections with exacerbated immune responses than other known genotypes of c. burnetii .
 acute q fever is an emergent and severe disease in french guiana . 
 we obtained 5 coxiella burnetii isolates from samples of patients from cayenne and found an epidemic clone circulating in cayenne . 
 this clone has caused pneumonia and endocarditis and seems to be more virulent than previously described strains . 