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PubMed2001

Comparison of virulence of Coxiella burnetii isolates from bovine milk and from ticks.

Laboratory animals (mice and guinea pigs) were infected with the isolates of Coxiella burnetii (Derrick, 1939) obtained from bovine milk (M18 and M35) and the ticks Ixodes ricinus (Linnaeus, 1758) and Dermacentor marginatus (Sulzer, 1776) (Kl3 and Kl6, respectively), and with the reference strain Nine Mile. Neither mortality nor lethality occurred with the mice. Antibody response in mice infected with isolates from milk was lower (1:16-512) than that from ticks (1:32-4096). Onset of seropositivity also occurred later - on the 10th day post-infection (p.i.) for M18 and M35 in comparison with the 7th day for Kl3 and Kl6. In guinea pigs, infection manifested by fever. The fever was less evident in guinea pigs infected with isolates from milk (39.5-40.1 degrees C) than in guinea pigs infected with isolates from ticks (39.5-40.6 degrees C). Partially engorged females of Dermacentor reticulatus (Fabricius, 1794) were inoculated with isolates M18 and Kl3. No differences in the multiplication of C. burnetii in haemocytes between these two isolates were ascertained.

Animals↗
PubMed2005

Spread of Coxiella burnetii infection in a flock of sheep after an episode of Q fever.

In October 1998, two abortions associated with Coxiella burnetii occurred in a group of 34 pregnant ewes in the sheep flock belonging to INRA Tours-Nouzilly. The flock was kept in groups of approximately 40 ewes, which were housed together in the same accommodation. The prevalence of C burnetii infection in the groups was investigated by using ELISA and PCR tests, which revealed a high prevalence of C burnetii. The ewes were treated with oxytetracycline to reduce the shedding of C burnetii and to prevent further abortions. Nevertheless, five abortions attributed to C burnetii occurred in January and March 1999 in three groups of ewes, and 24 of the ewes still shed the bacteria into their vaginal tracts. In addition, a serological study was carried out during the first year of life of the female lambs born in 1999 and 2000; 12 per cent of 113 lambs born in 1999 were seropositive for C burnetii by ELISA, and half of the ELISA-positive lambs were born either to serologically positive ewes or to dams that excreted the pathogen into their vaginal tracts. However, all the 150 lambs born in 2000 were ELISA-negative, suggesting that the preventive measures undertaken had suppressed both the abortions and the shedding of C burnetii, and reduced the transmission of the agent.

Abortion, Veterinary↗
PubMed1970

Biochemistry of Coxiella burnetii: 6-phosphogluconic acid dehydrogenase.

Purified preparations of the rickettsial agent, Coxiella burnetii, have been examined for their ability to decarboxylate 6-phosphogluconate. The enzyme 6-phosphogluconic acid dehydrogenase [6-phospho-d-gluconate: NADP (nicotinamide adenine dinucleotide phosphate) oxidoreductase (decarboxylating), EC 1.1.1.44] was detected in extracts, but not in whole-cell preparations of C. burnetii. Both extracts and whole cells were shown to be free from contaminating host enzyme activity. Partial characterization of the enzyme has shown that it is substrate-dependent, specific for NADP, and requires magnesium for activity. The pH optimum of the rickettsial enzyme is 8.0.

Animals↗
PubMed1996

Epidemiological features of Coxiella burnetii infection in England and Wales: 1984 to 1994.

Q fever is an important zoonosis caused by the rickettsial organism Coxiella burnetii, which can result in life threatening illness, especially in those with an underlying cardiac defect. C. burnetii infections in England and Wales reported to the PHLS Communicable Disease Surveillance Centre between 1984 and 1994 were reviewed. A total of 1117 cases were reported, a third of which came from the South Western region. The annual totals fell over this period. The mean age of cases was 45 years, and 74% were men. Reports peaked in the month of May. Contact with animals, mainly cattle and sheep, was reported in 60 cases. Occupationally acquired infection was reported for 24 cases including abattoir workers, farmers, veterinary surgeons, hide handlers, and butchers. Forty-seven per cent of cases presented with respiratory symptoms, 7% with heart disease, and 5% with hepatitis. Seven per cent of cases reported travel abroad before becoming ill. Joint veterinary and medical investigations should be undertaken to establish the natural history of C. burnetii infection in England and Wales and formulate policies to prevent acute and chronic infections.

Adult↗
PubMed1990

Localization of DNA in Coxiella burnetii by post-embedding immunoelectron microscopy.

The deoxyribonucleic acid of Coxiella burnetii was detected with monoclonal antibodies against single-stranded and double-stranded DNA by post-embedding immunoelectron microscopy. The antibody labeled the nucleoid of the spore, the small cell variant (SCV), and the large cell variant (LCV). The DNA was segregated completely in both the spore and the mother cell. At the terminal stage of development of the spore, the loss of nuclear morphology in the mother cell was related to the reduction in the labeling of the nucleoid. The mother cell was therefore killed for the development and release of the spore.

Coxiella↗
PubMed1978

Attempts at demonstration of lipopolysaccharide in phase II Coxiella burnetii.

Comparison of some properties of phase I and phase II Coxiella burnetii cells suggests the presence of lipopolysaccharide (LPS) also in the surface structures of phase II cells. Polysaccharide chains were released from them by mild acid hydrolysis and corpuscular residues resulting from such hydrolysis elicited in rabbits anti-lipid A-antibodies. Toxicity for adrenalectomized and actinomycin D-sensitized mice was demonstrated with phase I cells, but not with much higher concentrations of phase II cells. By contrast, the extent of protection against formation of ascitic tumour in mice with comparable concentrations of phase I and phase II cells was similar.

Animals↗
PubMed2003

Acidification modulates the traffic of Trypanosoma cruzi trypomastigotes in Vero cells harbouring Coxiella burnetii vacuoles.

We studied the fate of different Trypanosoma cruzi trypomastigote forms after they invade Vero cells persistently colonised with Coxiella burnetii. When the invasion step was examined we found that persistent C. burnetii infection per se reduced only tissue-culture trypomastigote invasion, whereas raising vacuolar pH with Bafilomycin A1 and related drugs, increased invasion of both metacyclic and tissue-culture trypomastigotes when compared with control Vero cells. Kinetic studies of trypomastigote transfer indicated that metacyclic trypomastigotes parasitophorous vacuoles are more efficiently fused to C. burnetii vacuoles. The higher tissue-culture trypomastigote hemolysin and transialidase activities appear to facilitate their faster escape from the parasitophorous vacuole. Sialic acid deficient Lec-2 cells facilitate the escape of both forms. Endosomal-lysosomal sequential labelling with EEA1, LAMP-1, and Rab7 of the parasitophorous vacuoles formed during the entry of each infective form revealed that the phagosome maturation processes are also distinct. Measurements of C. burnetii vacuolar pH disclosed a marked preference for trypomastigote fusion with more acidic rickettsia vacuoles. Our results thus suggest that intravacuolar pH modulates the traffic of trypomastigote parasitophorous vacuoles in these doubly infected cells.

Animals↗
PubMed1986

Overlapping deletion in two spontaneous phase variants of Coxiella burnetii.

Chromosomal DNA from the Nine Mile phase I strain of Coxiella burnetii (CB9MIC7) was cloned into the cosmid vector pHC79. The resulting gene library was probed with a radiolabelled HaeIII fragment present in the parental strain but absent from a spontaneously derived Nine Mile phase II strain (CB9MIIC4). The insert, which includes the missing HaeIII fragment, was 38.5 kb in length. When DNA from this cosmid clone was hybridized to genomic DNA of the parental CB9MIC7 and its derivative CB9MIIC4, a number of fragments were missing or altered in the latter strain. Restriction mapping localized the fragments to a contiguous portion of the chromosomal DNA fragment. The data were consistent with an 18 kb deletion in the chromosome of CB9MIIC4. Another intrastrain spontaneous derivative, CB9MI514, also lacked the sentinel HaeIII fragment and carried a deletion of approximately 29 kb within the same cloned insert. Both deletions appeared to share a common terminus, within the limits of resolution. In all other strains investigated, both phase I and phase II, the DNA represented by the insert seemed intact. The strains examined were representative of various stages of phase variation. The relationship between the observed deletions and the mechanism of phase transition in Nine Mile strains is discussed.

Chromosome Deletion↗
PubMedDate not supplied

On the determination of "Kdo-like substance" in the lipopolysaccharide from Coxiella burnetii strain nine mile in phase II.

The lipid A proximal carbohydrate region in a lipopolysaccharide (LPS II) isolated from Coxiella burnetii strain Nine Mile in avirulent phase II has been reinvestigated. So called "Kdo-like substance", reported to be present in LPS II (Schramek and Mayer, 1982) has been unambiguously identified as the 3-deoxy-D-manno-2-octulosonic acid (Kdo).

Coxiella burnetii↗
PubMed1988

Immune modulation by Coxiella burnetii: characterization of a phase I immunosuppressive complex differentially expressed among strains.

Coxiella burnetii, the etiological agent of Q fever, possesses immunomodulatory activity which positively and negatively regulates host immune responses. We wish to determine the Coxiella strain differences and the chemical nature of cellular components suppressing lymphocyte responsiveness. The bacterial components responsible for the immunomodulatory activity are associated with phase I cells. In its natural state, the phase I cell-associated, immunosuppressive complex (ISC) was resistant to chemical and enzymatic treatment. The ISC was inactivated and rendered accessible by chloroform-methanol (CM) (4:1) extraction of phase I cells which produced a CM residue (CMRI) and CM extract (CME). The suppressive components in either CMRI or CME did not induce ISC activity in the host when injected separately. Reconstitution of the CMRI with CME prior to injection produced the same pathological reactions characteristic of phase I cells. The CMRI suppressive component was sensitive to alkali, acid, periodate, lysozyme, and neuraminidase, but resistant to lipase and protease. An active component of CMRI was attached to the cell matrix by disulphide bonds. The amphipathic, lipophilic, CME suppressive component was ubiquitously distributed in procaryotes and eukaryotes because ISC activity of CMRI was regained after association with reagent-grade lipids and different CMEs. The ISC was expressed by phase I strains with smooth lipopolysaccharide (LPS) but not by phase II strains with rough LPS. Phase I heart valve strains carrying significant amounts of rough LPS did not express all of the biological properties of the ISC. The LPS molecule induced immune enhancement without immunosuppression. Thus, expression of the ISC showed strain variation and may be under genetic control. The complete details of the chemical composition and active components of the ISC should prove useful for biological-response-modification studies.

Adsorption↗
PubMed2005

Abdominal aortic aneurysm and Coxiella burnetii infection: report of three cases and review of the literature.

Coxiella burnetii, the etiologic agent of Q fever, is mainly responsible for endocarditis with negative blood culture results, but only a few cases of C. burnetii infections of aortic aneurysms have been published. We report three cases of abdominal aortic aneurysms treated in patients with Q fever infection with simultaneous endocarditis (n = 1) and previous history of cardiac valve replacement for endocarditis (n = 1). A coeliac aortic aneurysm was diagnosed in one patient treated for acute Q fever with persistent serologic results showing chronic infection despite adequate antibiotic therapy and without endocarditis. Resection of the aneurysm cured the chronic infection, and C. burnetii was identified by culture of the aneurysmal wall. In the two other cases, chronic infection of C. burnetii was diagnosed by serologic examination after surgery for an abdominal aortic aneurysm. One patient with negative blood culture results had amaurosis fugax due to endocarditis and required aortic valve replacement; recurrent fever without evidence of valve dysfunction or infection developed in one patient who had had prosthetic cardiac valve replacement 6 months earlier for endocarditis. Aortic aneurysms were treated with in situ prosthetic grafts and long-term antibiotic therapy. At a mean follow-up of 12 years, no septic aortic complications occurred, and serologic test results have remained negative. The presence of an aortic aneurysm and cardiac valve disease seems to be a predisposing factor for chronic C. burnetii infection. Diagnosis particularly relies on the physician's awareness of this condition and is confirmed by serologic examination. Aortic aneurysm resection is mandatory to cure the chronic infection and must be associated with long-term antibiotic therapy.

Aged↗
PubMed1978

Effects of infection with Coxiella burnetii on synthesis of RNA in L cells.

Experimental infections with Coxiella burnetii augment rates of ribonucleic acid (RNA) synthesis in guinea pigs. The activity of deoxyribonucleic acid-dependent RNA polymerase in L cells persistently infected with C. burnetii was threefold greater than that in unifected cells; the polymerase activity in infected cells was predominantly of class I, whereas that in uninfected cells was predominantly of class II. A search for regulatory factors of polymerase activity revealed that preincubation of uninfected L cells with lipopolysaccharide of C. burnetii or with putrescine, spermidine, or spermine enhanced polymerase activities. Because sonicated nuclei were assayed rather than purified enzymes, it cannot be stated definitely whether augmented polymerase activites were consequences of direct effects of infection on polymerases or a triggering of secondary regulatory factors.

Animals↗
PubMed2004

Measurement of the antibiotic susceptibility of Coxiella burnetii using real time PCR.

The objective of this study was to determine MICs of antibiotics for two reference strains of Coxiella burnetii using real time quantitative PCR. The method was very sensitive and specific and allowed the evaluation of the doubling time of Nine Mile and Q212 strains: 37 and 15 h, respectively. Dose response curves of antibiotics were used to determine MICs. Those of doxycycline, fluoroquinolone compounds and rifampicin were in the range 1-4 mg/l. Telithromycin was the most effective macrolide compound with MICs of 1-2 mg/l. The results confirmed previous reports on the accuracy of this new method for the determination of the antibiotic susceptibility of C. burnetii and could be used for the screening of new drugs.

Animals↗
PubMed1989

[Detection of antibodies to Coxiella burnetii antigens using immunoenzyme analysis].

In trials the optimal conditions of immuno-enzyme analysis for detection of antibodies to Coxiella burnetii were revealed. It was proved that the sensitivity of ELISA exceeds the sensitivity of reaction of complement binding not less than in 100 times. The effectiveness of ELISA was shown to be higher than that of reaction of complement binding both at early terms of disease (up to 14th day) and in persons having the disease rather long ago (1-2 years ago).

Antibodies, Bacterial↗
PubMed1997

Study of the 16S-23S ribosomal DNA internal spacer of Coxiella burnetii.

The complete 16S-23S ribosomal DNA (rDNA) internal transcribed spacer (ITS) of 22 isolates of the obligate intracellular bacterium Coxiella burnetii, the agent of Q fever, were amplified by the polymerase chain reaction (PCR) and sequenced using an automated laser fluorescent DNA sequencer. The ITS measured 497 base pairs (bp) and encoded isoleucine-tRNA and alanine-tRNA. The comparison of the sequence alignments of the 22 C. burnetii strains revealed very high levels of sequence similitary (> 99%) although they had different geographic origins and phenotypic characteristics. Sequencing of the 16S-23S rDNA ITS of C. burnetii could be utilized for identification of the bacterium but is not applicable to studies of epidemiology, virulence and taxonomy.

Animals↗
PubMed1983

Different antigenic properties of lipopolysaccharides isolated from Coxiella burnetii in phase I and pure phase II.

Lipopolysaccharides (LPSs) isolated from Coxiella burnetii cells in phase I and pure phase II behaved as antigens reacting in serological tests (passive haemolysis, passive haemolysis inhibition, complement-fixation, immunoprecipitation) with sera of rabbits immunized with C. burnetii strains in the corresponding phase. No cross-reactions were observed between LPSs isolated from C. burnetii in phase I and phase II, respectively.

Complement Fixation Tests↗
PubMed1998

In vitro susceptibility of Coxiella burnetii to trovafloxacin in comparison with susceptibilities to pefloxacin, ciprofloxacin, ofloxacin, doxycycline, and clarithromycin.

The antibiotic susceptibilities of eight Greek isolates of Coxiella burnetii to trovafloxacin were determined by the shell vial assay. MICs of trovafloxacin and ofloxacin ranged from 1 to 2 microg/ml, those of pefloxacin ranged from 1 to 4 microg/ml, those of ciprofloxacin ranged from 4 to 8 microg/ml, those of doxycycline ranged from 1 to 2 microg/ml, and those of clarithromycin ranged from 2 to 4 microg/ml. Trovafloxacin exhibited no activity against C. burnetii at 4 microg/ml.

Anti-Infective Agents↗