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At least 19 recordsLinked to original sources
PubMed2001

Lack of association between Kawasaki syndrome and infection with Rickettsia conorii, Rickettsia typhi, Coxiella burnetii or Ehrlichia phagocytophila group.

BACKGROUND: The etiology of Kawasaki syndrome (KS) is unknown. Rickettsiae, intracellular microorganisms that invade the vascular endothelium, might cause KS. OBJECTIVES: To investigate whether there is an association between KS and infection with Rickettsia conorii, Rickettsia typhi, Coxiella burnetii or Ehrlichia phagocytophila group. METHODS: All children who were diagnosed with KS at the University of Athens Second Department of Pediatrics from December, 1999, through November, 2000, were prospectively studied. Paired serum specimens were obtained from all patients and antibody titers against R. conorii, R. typhi, C. burnetii and E. phagocytophila group were assessed by microimmunofluorescence assay. RESULTS: Eleven children with a median age of 2.5 years were included in the study. A 15-month-old child had a 4-fold rise of antibody titers against C. burnetii, which is indicative of acute Q fever. The patient had a history of recent exposure to possible sources of C. burnetii. The remaining patients tested negative for the presence of antibodies against R. conorii, R. typhi, C. burnetii and E. phagocytophila group. CONCLUSIONS: Our study does not provide serologic evidence that KS is the result of infection with R. conorii, R. typhi, C. burnetii or E. phagocytophila group. It is suggested that C. burnetii may cause a KS-like illness in young children.

Boutonneuse Fever↗
PubMed2000

In vitro activities of telithromycin (HMR 3647) against Rickettsia rickettsii, Rickettsia conorii, Rickettsia africae, Rickettsia typhi, Rickettsia prowazekii, Coxiella burnetii, Bartonella henselae, Bartonella quintana, Bartonella bacilliformis, and Ehrlichia chaffeensis.

In vitro activities of telithromycin compared to those of erythromycin against Rickettsia spp., Bartonella spp., Coxiella burnetii, and Ehrlichia chaffeensis were determined. Telithromycin was more active than erythromycin against Rickettsia, Bartonella, and Coxiella burnetii, with MICs of 0.5 microg/ml, 0.003 to 0.015 microg/ml, and 1 microg/ml, respectively, but was inactive against Ehrlichia chaffeensis.

Anti-Bacterial Agents↗
PubMed2003

A case of pleurisy associated with antibodies to Rickettsia conorii.

Rickettsia conorii is endemic in Mediterranean area. We describe an unusual sace of R. Conorii infection, which concerns a farmer with clinical, radiological and cytological findings of pleurisy without evidence of malignancy. An elevated antibody titre for R. Conorii was observed, using an indirect immunofluorescent antibody test. After treatment with Doxycycline, the patient presented a significant improvement of his clinical and radiological image and a four-fold decrease of the antibody titre for R. conorii.

Adult↗
PubMed2005

Ku70, a component of DNA-dependent protein kinase, is a mammalian receptor for Rickettsia conorii.

Rickettsia conorii, a strictly intracellular and category C priority bacterial pathogen (NIAID), invades different mammalian cells. Although some signaling events involved in bacterial entry have been documented, the bacterial and host proteins mediating entry were not known. We report the identification of the Ku70 subunit of DNA-dependent protein kinase (DNA-PK) as a receptor involved in R. conorii internalization. Ku70 is recruited to R. conorii entry sites, and inhibition of Ku70 expression impairs R. conorii internalization. Bacterial invasion is dependent on the presence of cholesterol-enriched microdomains containing Ku70. R. conorii infection stimulates the ubiquitination of Ku70. In addition, the ubiquitin ligase c-Cbl is recruited to R. conorii entry foci, and downregulation of endogenous c-Cbl blocks bacterial invasion and Ku70 ubiquitination. An affinity chromatography approach identified the rickettsial protein rOmpB as a ligand for Ku70. This is the first report of a receptor-ligand interaction involved in the internalization of any rickettsial species.

Actins↗
PubMed2002

Expression of green fluorescent protein in Rickettsia conorii.

Rickettsiae are obligate intracellular class III pathogens for which genetic manipulation has only recently been shown to be feasible. Such experiments were restricted to the typhus group rickettsiae, namely R. typhi and R. prowazekii. Here we report the first genetic manipulation of Rickettsia conorii, the bacterial agent responsible for the Mediterranean spotted fever. A gene encoding a variant of the green fluorescent protein under the control of the sterically repressed promoter (srp) from E. coli was integrated into the genome of this bacteria and detected by FACS analysis.

Animals↗
PubMed2002

Prevalence of Rickettsia conorii and Rickettsia typhi infections in the population of northern Greece.

Seroepidemical surveys concerning the prevalence of Rickettsia conorii and Rickettsia typhi have never been studied in northern Greece. We examined 1,584 sera samples from residents of northern Greece for the detection of antibodies to R. conorii and to R. typhi by means of immunofluorescence assay. In addition, we compared the prevalence of rickettsial infections among the demographic variables of sex, age, occupation, and area of residence. Antibodies to R. conorii and R. typhi were found in 125 (7.9%) and 31 (2.0%) of the examined subjects, respectively. The prevalence of antibodies to R. conorii correlated with increasing age and was statistically higher in men. Farmers had significantly higher prevalence of antibodies to both species of rickettsiae studied versus other professions. Residents of rural areas showed a statistically higher prevalence for R. conorii versus urban residents, although this difference was not demonstrated for R. typhi. We also detected differences in the prevalence of rickettsial infections among the different prefectures. Our data show the wide distribution of R. conorii in northern Greece and indicate the presence of R. typhi.

Adolescent↗
PubMed1995

Prevalence of antibodies to Coxiella burnetti, Rickettsia conorii, and Rickettsia typhi in seven African countries.

The prevalences of antibodies reactive with Coxiella burnetti, Rickettsia conorii, and Rickettsia typhi were determined by indirect fluorescent antibody testing of sera from seven African countries. The seroprevalences of antibodies reactive with C. burnetti and R. conorii in countries from North Africa were similar to those reported from southern Europe. In countries of sub-Saharan Africa, the seroprevalence of antibodies reactive with C. burnetti varied greatly; the generally higher figures for West Africa, where stock breeding is prominent, suggested that domestic animals might be the main reservoirs of infection. The prevalence of antibodies to the recently described species Rickettsia africae was higher than that reported for spotted fever-group rickettsiae from elsewhere in the world and paralleled the distribution of Amblyomma species. Western blot results suggested that the antibodies detected were more likely to be reactive with R. africae than with R. conorii, the main vector of which (Rhipicephalus species) rarely feeds on humans. The seroprevalences of antibodies reactive with R. typhi were higher in coastal regions, where Rattus norvegicus--the natural host of the vector Xenopsylla--is more prevalent, than in inland areas.

Africa↗
PubMed1990

Secretion of tissue-type plasminogen activator and plasminogen activator inhibitor by Rickettsia conorii- and Rickettsia rickettsii-infected cultured endothelial cells.

Hemostasis abnormalities have been described in patients with Mediterranean spotted fever and Rocky Mountain spotted fever. Evidence of the activation of the fibrinolytic system has been obtained in both diseases. After experimental Rocky Mountain spotted fever, an elevated level of fibrinogen was found in parallel with the activation of the fibrinolytic system and transient elevation of the tissue-type plasminogen activator. Later protein is mainly synthesized by endothelial cells. The ability to culture human endothelial cells in vitro provides a unique system to study the secretion of tissue-type plasminogen activator and of plasminogen activator inhibitor after rickettsial infection. Human vascular endothelial cells derived from the umbilical vein, when infected with Rickettsia conorii or Rickettsia rickettsii, secreted as much tissue-type plasminogen activator as control cells. The activity of plasminogen activator inhibitor however, was higher in the supernatants of infected cells than in those of control cells. This rickettsia-induced imbalance of the tissue-type plasminogen activator-inhibitor pair was a very early event after in vitro infection. The involvement of this system during Mediterranean spotted fever and Rocky Mountain spotted fever remains to be demonstrated.

Antibodies, Monoclonal↗
PubMed2006

Evaluation of IgG antibody response against Rickettsia conorii and Rickettsia slovaca in patients with DEBONEL/TIBOLA.

The aim of the study was to determine the IgG antibody response to spotted fever group Rickettsia (SFGR) R. conorii and R. slovaca, and its specificity and sensitivity in patients with DEBONEL/TIBOLA. A prospective study of 31 patients with DEBONEL was carried out from January 2001 to May 2004. The SFGR serology testing (IgG IFA) for the diagnosis of DEBONEL/TIBOLA showed 61% sensitivity and 100% specificity. The R. slovaca antigen allowed the diagnoses in 18 of the 31 patients (58%), and 17 patients (55%) were diagnosed with this disease using R. conorii antigen. Therefore, using R. slovaca as antigen did not improve the sensitivity of the assay.

Antibodies, Bacterial↗
PubMed1984

[Electron microscopic characteristics of the action of penicillin and vancomycin on Rickettsia conorii and Rickettsia akari in vitro].

The possibility of L-transformation for two species of Rickettsia of the tick group (R. conorii and R. akari) was studied with light and electron microscopy. The experiments were performed on the cultures of L-cells (murine fibroblasts). Penicillin and vancomycin were used as the transforming agents. Electron microscopy revealed clear changes in the morphological structure of both species when the doses of penicillin and vancomycin were 50-100 and 250-1500 micrograms/ml, respectively. The antibiotics had a morphologically analogous effect on both species of Rickettsia. The resulting morphological structures were large oval spheroplast-like cells with significant expansion of the periplasmic space up to 1 X 1.75 micron under the effect of penicillin and 0.5 X 0.7 micron under the effect of vancomycin. R. akari was somewhat more sensitive to the antibiotics. Electron microscopy of the morphological changes in the Rickettsia induced by penicillin and vancomycin showed that they were similar to the changes observed in gram-negative bacteria on their L-transformation and to the penicillin forms of chlamydia (galprovia) and R. prowazekii. They may be considered as a phase of unbalanced growth and represent the initial stage of L-transformation.

Cell Wall↗
PubMed2005

Proposal to create subspecies of Rickettsia conorii based on multi-locus sequence typing and an emended description of Rickettsia conorii.

BACKGROUND: Rickettsiae closely related to the Malish strain, the reference Rickettsia conorii strain, include Indian tick typhus rickettsia (ITTR), Israeli spotted fever rickettsia (ISFR), and Astrakhan fever rickettsia (AFR). Although closely related genotypically, they are distinct serotypically. Using multilocus sequence typing (MLST), we have recently found that distinct serotypes may not always represent distinct species within the Rickettsia genus. We investigated the possibility of classifying rickettsiae closely related to R. conorii as R. conorii subspecies as proposed by the ad hoc committee on reconciliation of approaches to bacterial systematics. For this, we first estimated their genotypic variability by using MLST including the sequencing of 5 genes, of 31 rickettsial isolates closely related to R. conorii strain Malish, 1 ITTR isolate, 2 isolates and 3 tick amplicons of AFR, and 2 ISFR isolates. Then, we selected a representative of each MLST genotype and used multi-spacer typing (MST) and mouse serotyping to estimate their degree of taxonomic relatedness. RESULTS: Among the 39 isolates or tick amplicons studied, four MLST genotypes were identified: i) the Malish type; ii) the ITTR type; iii) the AFR type; and iv) the ISFR type. Among these four MLST genotypes, the pairwise similarity in nucleotide sequence varied from 99.8 to 100%, 99.4 to 100%, 98.2 to 99.8%, 98.4 to 99.8%, and 99.2 to 99.9% for 16S rDNA, gltA, ompA, ompB, and sca4 genes, respectively. Representatives of the 4 MLST types were also classified within four types using MST genotyping as well as mouse serotyping. CONCLUSION: Although homogeneous genotypically, strains within the R. conorii species show MST genotypic, serotypic, and epidemio-clinical dissimilarities. We, therefore, propose to modify the nomenclature of the R. conorii species through the creation of subspecies. We propose the names R. conorii subsp. conorii subsp. nov. (type strain = Malish, ATCC VR-613), R. conorii subspecies indica subsp. nov. (type strain = ATCC VR-597), R. conorii subspecies caspia subsp. nov. (type strain = A-167), and R. conorii subspecies israelensis subsp. nov. (type strain = ISTT CDC1). The description of R. conorii is emended to accomodate the four subspecies.

Gene Expression Regulation, Bacterial↗
PubMed2005

Motor and sensory polyneuritis with distal conduction failure as uncommon complication of an acute Rickettsia conorii infection.

Rickettsia conorii is endemic in the Mediterranean region. Infections are mostly benign and neurological involvement is unusual. We describe a case of a man who presented with acute facial nerve palsy followed by flaccid tetraparesis due to an electrophysiologically established polyneuritis with distal conduction failure. Elevated IgM antibody titres for R. conorii were documented by indirect immunofluorescent antibody test. After doxycycline therapy, the patient presented a rapid clinical improvement. Repeated electrophysiological examinations revealed significantly restored compound muscles, and sensory action potentials, corresponding to the clinical course after treatment and ex juvantibus, indicate the causative relation between R. conorii infection and the described clinical syndrome.

Aged↗
PubMed1997

Distribution of immunogenic epitopes on the two major immunodominant proteins (rOmpA and rOmpB) of Rickettsia conorii among the other rickettsiae of the spotted fever group.

Forty-four monoclonal antibodies were raised against strain Seven, the type strain of Rickettsia conorii. Of these 44 monoclonal antibodies, 13, 27, and 4 were demonstrated to be directed against the 116-kDa protein (rOmpA), the 124-kDa protein (rOmpB), and lipopolysaccharide-like antigen, respectively. The antiprotein monoclonal antibodies were found to be directed against 29 distinct epitopes, which were located on the two major immunodominant proteins discussed above. Further analysis showed that strain-specific epitopes were located on the rOmpA protein and species- and subgroup-specific epitopes were located on the rOmpB protein. R. conorii Manuel, Indian tick typhus rickettsia, and Kenya tick typhus rickettsia also possessed all 29 epitopes, whereas the other rickettsiae of the spotted fever group (SFG) expressed between 3 and 25 epitopes, with the exception of Rickettsia helvetica, R. akari, and R. australis which did not possess any epitopes. Additional analyses by Western immunoblotting confirmed that the epitopes shared among the SFG rickettsiae were located on the same two high-molecular-mass proteins as on R. conorii. However, although epitopes on the R. conorii rOmpB protein were expressed on the rOmpB proteins of most other SFG rickettsiae, some were found on the rOmpA proteins of R. aeschlimannii, R. rickettsii, and R. rhipicephali. Both proteins possessing the common epitopes were found to have different sizes in the SFG rickettsial species. The different distributions of common epitopes in the SFG rickettsiae were also used to build a taxonomic dendrogram, which demonstrated that all the R. conorii strains formed a relatively independent cluster within the SFG rickettsiae and was generally consistent with previously proposed taxonomies.

Antibodies, Monoclonal↗
PubMed1990

Prevalence of antibodies to Rickettsia conorii Coxiella burnetii and Rickettsia typhi in Salamanca Province (Spain). Serosurvey in the human population.

The Salamanca Province of Spain is an endemic zone for Mediterranean spotted fever. In this area, only one case of Q fever has been reported and typhus group rickettsial diseases have never been diagnosed. To obtain a panoramic view of the presence of antibodies to the most ubiquitous rickettsial agents, 400 sera specimens from a statistically representative sample of the human population of Salamanca City and its surrounding province were subjected to indirect microimmunofluorescent test for antibodies against Rickettsia conorii, Coxiella burnetti, phase II, and Rickettsia typhi antigens. Titers greater than or equal to 1:40 to R. conorii were found in 73.5% of the sera. Positivity was more common in subjects who reported closer contact with the natural environment and/or with domestic animals. Seropositivity to C. burnetti, phase II, was detected in 50.2% of sera. These positive cases were related to rural environmental factors and to previous contact with animals. The frequency of antibodies increased with age showing a progressive exposure to the rickettsial antigen. The prevalence of antibodies to R. conorii and C. burnetii in the human population of Salamanca Province is higher than that reported from any other geographic zone. The study of antibodies to R. typhi showed that 12.5% of the sera had titers greater than or equal to 1:40. According to our results, seropositivity to this rickettsial antigen cannot be related to any particular group of population nor interpreted totally as cross reactivity with R. conorii. Our data show a wide distribution of R. conorii and C. burnetii antigens in Salamanca Province, and also indicate the presence of R. typhi antigens in this area.

Adolescent↗
PubMed1997

Bacteriostatic and bactericidal activity of levofloxacin against Rickettsia rickettsii, Rickettsia conorii, 'Israeli spotted fever group rickettsia' and Coxiella burnetii.

Levofloxacin, the L-isomer of ofloxacin, is approximately twice as active as ofloxacin against most Gram-positive and Gram-negative bacteria, and has improved intracellular pharmacokinetic and pharmacodynamic properties. The present work deals with the in-vitro activity of levofloxacin against the obligate intracellular bacteria Rickettsia rickettsii, Rickettsia conorii, 'Israeli spotted fever group rickettsia' (Israeli SFGR) and Coxiella burnetii. Fluoroquinolones, including ofloxacin, have previously been shown to be bacteriostatic against Rickettsia spp. and C. burnetii in vitro. They are reliable alternatives to tetracycline therapy for Mediterranean spotted fever, scrub typhus and acute Q fever. Levofloxacin was bacteriostatic against R. rickettsii, R. conorii and the Israeli SFGR at concentrations of 0.5-1 mg/L, as determined by both a plaque assay and a dye uptake assay. It was also bacteriostatic against C. burnetii isolates, including the Nine Mile, Priscilla and Q212 strains, at concentrations of 0.5-2 mg/L, as determined using the shell vial assay. Overall, levofloxacin could inhibit rickettsial growth at concentrations equal to or half of those necessary for growth inhibition by ofloxacin. Levofloxacin was not bactericidal against C. burnetii at concentrations up to 4 mg/L.

Anti-Infective Agents↗