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Biomedical subjects

D Raoult

Publications and source records attributed to D Raoult.

At least 577 records · Page 32Linked to original sources
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Bartonella quintana invades and multiplies within endothelial cells in vitro and in vivo and forms intracellular blebs.

Bartonella quintana, the aetiologic agent of trench fever, has recently been implicated in culture-negative endocarditis and bacteraemia amongst homeless people. B. quintana is a fastidious slow-growing organism. A tissue culture system of human endothelial cells was developed in which B. quintana grew intracellularly. Observation of the different steps during infection of these cells demonstrated that the bacteria adhered to and penetrated the cells by phagocytosis. During the preadherence stage, most bacteria exhibited surface appendages that resembled those described for Salmonella typhimurium and which may mediate specific interactions between the eucaryotic cell and the bacterium. Soon after the engulfment step, the bacterium appeared in a cell vacuole where it multiplied, giving the typical aspect of morulae which has also been reported with Ehrlichiae or Chlamydiae. In older cultures, the coexistence of bacteria and huge quantities of vesicle-like structures in the same vacuole were noted. These vesicle-like structures were also found with agar-grown bacteria and were identified as membrane blebs. Microscopic observation of heart valves from B. quintana endocarditis patients demonstrated the intracellular location of B. quintana in vivo. This intracellular location of B. quintana should now be considered in further studies on the pathogenesis of the diseases it causes.

Bacterial Adhesion↗
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Jail fever (epidemic typhus) outbreak in Burundi.

We recently investigated a suspected outbreak of epidemic typhus in a jail in Burundi. We tested sera of nine patients by microimmunofluorescence for antibodies to Rickettsia prowazekii and Rickettsia typhi. We also amplified and sequenced from lice gene portions specific for two R. prowazekii proteins: the gene encoding for citrate synthase and the gene encoding for the rickettsial outer membrane protein. All patients exhibited antibodies specific for R. prowazekii. Specific gene sequences were amplified in two lice from one patient. The patients had typical clinical manifestations, and two died. Molecular techniques provided a convenient and reliable means of examining lice and confirming this outbreak. The jail-associated outbreak predates an extensive ongoing outbreak of louse-borne typhus in central eastern Africa after civil war and in refugee camps in Rwanda, Burundi (1), and Zaire.

Adult↗
PubMedDate not supplied

Murine typhus in travelers returning from Indonesia.

We report the first three documented cases of murine typhus imported into Europe from Indonesia, discuss clues for the diagnosis of the disease, and urge that murine fever be considered in the diagnosis of febrile disease in travelers.

Adult↗
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Epidemic typhus imported from Algeria.

We report epidemic typhus in a French patient returning from Algeria. The diagnosis was confirmed by serologic testing and the isolation of Rickettsia prowazekii in blood. Initially the patient was thought to have typhoid fever. Because body lice are prevalent in industrialized regions, the introduction of typhus to pediculosis-endemic areas poses a serious public health risk.

Aged↗
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New Rickettsiae in ticks collected in territories of the former soviet union.

Dermacentor nuttallii from Siberia, Rhipicephalus sanguineus from Crimea, and Rh. pumilio from the Astrakhan region were infected with Rickettsia sibirica (12%), R. conorii (8%), and the Astrakhan fever agent (3%), respectively. Three new Rickettsiae of the R. massiliae genogroup were identified in ticks by 16S rDNA, gltA, and ompA sequencing.

Animals↗
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Evidence of Rickettsia helvetica infection in humans, eastern France.

A 37-year-old man living in eastern France seroconverted to Rickettsia helvetica in August 1997, 4 weeks after the onset of an unexplained febrile illness. Results of a serosurvey of forest workers from the area where the patient lived showed a 9.2% seroprevalence against R. helvetica. This organism may pose a threat for populations exposed to Ixodes ricinus ticks.

Adult↗
PubMedDate not supplied

A flea-associated Rickettsia pathogenic for humans.

A rickettsia named the ELB agent, or "Rickettsia felis," was identified by molecular biology techniques in American fleas in 1990 and later in four patients from Texas and Mexico. We attempted to isolate this rickettsia from infected fleas at various temperatures and conditions. A representative isolate of the ELB agent, the Marseille strain, was characterized and used to develop a microimmunofluorescence test that detected reactive antibodies in human sera. The ELB agent was isolated from 19 of 20 groups of polymerase chain reaction-proven infected fleas. The microimmunofluorescence results provided serologic evidence of infection by the ELB agent in four patients with fever and rash in France (2) and Brazil (2), supporting the pathogenic role of this rickettsia. Our successful isolation of this rickettsia makes it available for use in serologic tests to determine its clinical spectrum, prevalence, and distribution.

Animals↗
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Goat-associated Q fever: a new disease in Newfoundland.

In the spring of 1999 in rural Newfoundland, abortions in goats were associated with illness in goat workers. An epidemiologic investigation and a serologic survey were conducted in April 1999 to determine the number of infections, nature of illness, and risk factors for infection. Thirty-seven percent of the outbreak cohort had antibody titers to phase II Coxiella burnetii antigen >1:64, suggesting recent infection. The predominant clinical manifestation of Q fever was an acute febrile illness. Independent risk factors for infection included contact with goat placenta, smoking tobacco, and eating cheese made from pasteurized goat milk. This outbreak raises questions about management of such outbreaks, interprovincial sale and movement of domestic ungulates, and the need for discussion between public health practitioners and the dairy industry on control of this highly infectious organism.

Adult↗
PubMedDate not supplied

Legionella-like and other amoebal pathogens as agents of community-acquired pneumonia.

We tested serum specimens from three groups of patients with pneumonia by indirect immunofluorescence against Legionella-like amoebal pathogens (LLAPs) 1-7, 9, 10, 12, 13; Parachlamydia acanthamoeba strains BN 9 and Hall's coccus; and Afipia felis. We found that LLAPs play a role (albeit an infrequent one) in community-acquired pneumonia, usually as a co-pathogen but sometimes as the sole identified pathogen.

Adult↗
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[Molecular tools in the epidemiology of tick-borne bacterial diseases].

Molecular tools have been used to detect rickettsiae in ticks. In Ixodes ricinus ticks collected in France, we detected for the first time there an emerging pathogen, Rickettsia helvetica, and an Ehrlichia sp, closely related to the agent of human granulocytic ehrlichiosis. In Guadeloupe (French West Indies), we described the occurrence of African tick-bite fever due to Rickettsia africae, which had been previously reported in sub-Saharan Africa only. In Africa, we completed our knowledge about the distribution of R. africae (Mali, Niger, Sudan, Burundi), and detected for the first time Rickettsia mongolotimonae, an emerging pathogen. Anaplasma marginale the agent of bovine anaplasmosis was detected in Mali. Rickettsiae of unknown pathogenicity were detected in Mali and Niger.

Burundi↗
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[Genotyping of spotted tick fever rickettsiae, detected in Russia and Kazakhstan].

R. slovaca was first detected in the ticks D. marginatus gathered in the Stavropol Territory and the Voronezh Region (European Russia). The recently discovered rickettsial genotype DnS14 was first found in the ticks D. silvarum from Buryatia and D. niveus from the Karaganda Region (Central Kazakhstan). The rickettsial genotype RpA4 was most common in the ticks of the genus Dermacentor in Russia and Central Kazakhstan. An analysis of the spread of rickettsias of the STF group shows their close ecological relation to definite types of Ixodes. The rickettsias R. slovaca and RpA4 co-exist in the ticks D. marginatus and D. reticulatus (the western part of a Dermacentor area in Eurasia) and DnS14 and R. sibirica do in D. nuttalli and D. silvarum (the eastern part of the area). D. marginatus and D. reticulatus in the areas characterized by the most specific saturation of a Dermacentor area (the south of West Siberia) are carriers and reservoir of R. sibirica. The rickettsial genotype DnS28 may be now considered to be environmentally associated with one species of ticks--D. nuttalli. At least 6 genotypes of STF rickettsias--R. sibirica, R. astrahan fever (R. conorii), R. slovaca, RpA4, DnS14, DnS28--has been currently identified in Russia and Kazakhstan.

Animals↗
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[Detection of Rickettsia hulinii in ticks of the Haemaphysalis concinna species in Russia].

The presence of Rickettsia hulinii was detected in ticks of the Haemaphysalis concinna species in the Asiatic part of Russia. It was the first detection of these rickettsiae outside the territory of the Chinese People's Republic. This tick is spread over a broken area and may occur in different regions of Eurasia. At present at least 3 rickettsial species of the tick-borne spotted fever group were found in Ixodes ticks on the territory of Eastern Siberia: R. sibirica, known to be the etiological agent of tick-borne rickettsiosis, R. hulinii with proved pathogenicity for laboratory animals and R.DnS14 with no data available on its pathogenicity.

Animals↗