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Didier Raoult

Publications and source records attributed to Didier Raoult.

341 records · Page 19Linked to original sources
PubMed2002

Parachlamydiaceae: potential emerging pathogens.

Parachlamydiaceae, which naturally infect amoebae, form a sister taxon to the Chlamydiaceae on the basis of the Chlamydia-like cycle of replication and 80% to 90% homology of ribosomal RNA genes. Because intra-amoebal growth could increase the virulence of some intracellular bacteria, Parachlamydiaceae may be pathogenic. Arguments supporting a pathogenic role are that Chlamydia pneumoniae, a well-recognized agent of pneumonia, was shown to infect free-living amoebae and that another member of the Chlamydiales, Simkania negevensis, which has 88% homology with Parachlamydia acanthamoebae, has caused pneumonia in adults and acute bronchiolitis in infants. The recent identification of a 16S rRNA gene sequence of a Parachlamydiaceae from bronchoalveolar lavage is additional evidence supporting potential for pathogenicity.

Acanthamoeba↗
PubMed2002

Human infection caused by Leptospira fainei.

We report a human case of leptospirosis in which the spirochete was detected by dark-field microscopy examination of cerebrospinal fluid (CSF) and isolated from both CSF and blood. Leptospira fainei was identified by sequencing the 16S rDNA gene, which had been amplified by polymerase chain reaction. This case confirms the role of L. fainei as a human pathogen and extends its distribution to southern Europe.

Adult↗
PubMed2002

Human pathogens in body and head lice.

Using polymerase chain reaction and sequencing, we investigated the prevalence of Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis in 841 body lice collected from various countries. We detected R. prowazekii in body lice from Burundi in 1997 and in lice from Burundi and Rwanda in 2001; B. quintana infections of body lice were widespread. We did not detect B. recurrentis in any lice.

Animals↗
PubMed2002

First molecular evidence of new Bartonella spp. in fleas and a tick from Peru.

Fleas, lice, and ticks collected in Peru in a suburban area of Cusco in November 1998 were tested by polymerase chain reaction for the presence of Bartonella DNA using primers amplifying a fragment of the intergenic spacer region (ITS) gene. Three new Bartonella genotypes were detected in Pulex fleas self-collected from the beds and clothes of schoolchildren and adults. A fourth new genotype was also detected from a tick found on a sheep in the same area. One of the genotypes is closely related to B. vinsoni subsp. berkhoffii, and the others seem to originate from unknown Bartonella species, whose medical importance has yet to be clarified.

Animals↗
PubMed2002

Q fever endocarditis: over 14 years of surgical experience in a referral center for rickettsioses.

BACKGROUND AND AIM OF THE STUDY: Q fever endocarditis caused by Coxiella burnetii is the most important etiology of negative blood culture endocarditis. Without specific clinical findings, diagnosis is difficult and prevalence of this life-threatening disease is underestimated. METHODS: Q fever endocarditis was assessed in 19 patients (15 men, four women; age range: 36-79 years) by evaluating clinical and echocardiographic criteria and specific serology. All patients had evidence of pre-existing valvular disease, and 10 had a valvular prosthesis. Diagnosis was assessed in: the presence of unexplained fever (n = 5), heart failure with valvular dysfunction (n = 10), hemolysis (n = 1), glomerulonephritis (n = 1) and stroke (n = 2). A late diagnosis was made in eight patients, either during or after surgery. RESULTS: In all cases, usual blood cultures remained negative, despite specific serology being positive. Transthoracic and transesophageal echocardiography were conclusive in only six cases (four vegetations, two periannular abscesses). Surgery was indicated in 15 patients for heart failure or valvular dysfunction (n = 12), hemolysis (n = 1) and periannular abscess (n = 2). Intraoperative findings were suggestive of endocarditis in seven cases; valvular cultures were positive in 92% of cases. All patients were treated with combined doxycycline/ hydrochloroquine or quinolone, for a mean of 24 months (range: 6-60 months). Mean follow up was 40 months (range: 6-144 months). Two patients died from heart failure, one patient was lost to follow up, and 16 patients had no late relapses. CONCLUSION: Q fever is an underestimated cause of endocardititis, and early diagnosis is the key to good prognosis. The need for systematic serologic examination in case of valvular dysfunction, with or without endocarditis symptoms, is emphasized.

Adult↗
PubMedDate not supplied

Tropical rickettsioses.

In recent years, a bewildering array of emerging rickettsial pathogens have been described throughout the world, including in the tropics. Here we present an updated overview of scrub typhus, murine typhus, and epidemic typhus. We also present an update on the emerging spotted fever group rickettsioses described in the tropics through 2005, focusing on epidemiologic and clinical data and management.

Humans↗
PubMedDate not supplied

A novel alpha-Proteobacterium, Nordella oligomobilis gen. nov., sp. nov., isolated by using amoebal co-cultures.

Using an amoebal co-culture procedure, a novel alpha-Proteobacterium phylogenetically close to two uncultured aquatic bacteria was isolated. On the basis of phenotypic characterization and 16S rRNA gene sequence analysis, we propose the new genus and species Nordella oligomobilis gen. nov., sp. nov. The genus Nordella forms a well separated taxon in the order Rhizobiales within the alpha-2 subgroup of Proteobacteria. Its close relatives are environmental uncultured bacteria.

Acanthamoeba↗
PubMedDate not supplied

Tick- and flea-borne rickettsial emerging zoonoses.

Between 1984 and 2004, nine more species or subspecies of spotted fever rickettsiae were identified as emerging agents of tick-borne rickettsioses throughout the world. Six of these species had first been isolated from ticks and later found to be pathogenic to humans. The most recent example is Rickettsia parkeri, recognized as a human pathogen more than 60 years after its initial isolation from ticks. A new spotted fever rickettsia, R. felis was also found to be associated with fleas and to be a human pathogen. Similarly, bacteria within the family Anaplasmataceae have been considered to be of veterinary importance only, yet three species have been implicated in human diseases in recent years, including Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, Anaplasma phagocytophilum, the agent of human anaplasmosis (formerly known as "human granulocytic ehrlichiosis agent", E. equi and E. phagocytophila), and finally Ehrlichia ewingii, which causes granulocytic ehrlichiosis in humans. We present here an overview of the various tick- and flea-borne rickettsial zoonoses described in the last 20 years, focusing on the ecological, epidemiological and clinical aspects.

Anaplasmosis↗
PubMedDate not supplied

Molecular genetic methods for the diagnosis of fastidious microorganisms.

Technological innovations in the detection and identification of microorganisms using molecular techniques such as polymerase chain reaction (PCR) have ushered in a new era with respect to diagnostic microbiology. PCR using universal or specific primers followed by identification of amplified product, mainly by sequencing, has enabled the rapid identification of cultured or uncultured bacteria. Thus, PCR may allow quick diagnosis of infections caused by fastidious pathogens for which culture could be extremely difficult. However, several pitfalls, such as false positives, have been observed with PCR, underlining the necessity to interpret the results obtained with caution. At present, certain improvements in the molecular genetic methods may be helpful for the diagnosis of infectious diseases. Indeed, the recent development of bacterial genome sequencing has provided an important source of potential targets for PCR, allowing rational choice of primers for diagnosis and genotyping. In addition, the development of new techniques such as real-time PCR offers several advantages in comparison to conventional PCR, including speed, simplicity, reproducibility, quantitative capability and low risk of contamination. Herein, we review the general principles of PCR-based diagnosis and molecular genetic methods for the diagnosis of several hard-to-culture bacteria, such as Rickettsia spp., Ehrlichia spp., Coxiella burnetii, Bartonella spp., Tropheryma whipplei and Yersinia pestis.

Actinomycetales↗
PubMedDate not supplied

[Epidemiological evaluation of a possible outbreak in and nearby Tokat province].

Between the dates of May 4th-August 6th 2002, 46 cases were detected with abdominal pain nausea, vomiting, arthralgia/myalgia, headache, fever, diarrhea and rash, in the middle Blacksea and north inner Anatolia regions. Their laboratory findings yielded elevated levels of liver enzymes (AST, ALT, LDH), leucopenia and thrombocytopenia. As the infection was treated easily with tetracyclines, clinical diagnosis was considered to be rickettsiosis or ehrlichiosis. Serum and blood samples obtained from some of the patients were tested against Rickettsia, Ehrlichia, Leptospira and Coxiella, in the national and international laboratories. Samples from 19 patients were sent to National Reference Centre and WHO Collaborating Centre for Rickettsial Reference and Research Laboratory, France, and 7 of them were reported as acute Q fever while 8 of them were reported as passed Q fever (QF) cases. In May 2003, new cases with similar symptoms have been reported from the same regions, with different epidemiologic and serologic findings (tick exposure history was higher, response to tetracycline was lower, C. burnetii antibodies were negative), indicating a viral etiology. The samples of these patients have been sent to National Reference Centre and WHO Collaborating Centre for Arboviruses and Viral Heamorrhagic Fevers, France, and the initial reports were marked as Crimean Congo hemorrhagic fever virus (CCHFV). Then the serum samples of previous 26 patients which were stored in National Serum Bank have been retrospectively investigated for viral aetiology in the same center, and 17 of them have been found positive for CCHFV IgM antibodies. Four of these patients were diagnosed as acute QF in 2002, one was passed QF, 2 were negative for QF and 10 were patients not investigated for QF. As a result, the detection of the both infections together in the same area shows the essential need for further epidemiological investigations.

Adolescent↗
PubMedDate not supplied

Prevalence of skin infections in sheltered homeless.

In an attempt to determine the prevalence of various skin infections in the homeless population in Marseilles, France, we undertook a case control study. Cases were recruited among institutionalized homeless subjects during two snapshot investigations conducted in January 2002 and 2003 respectively. The control subjects were recruited from among those who presented at a clinic for pre-travel advice. We recruited 498 cases and 200 control subjects. Compared to control subjects, a significantly higher proportion of cases had skin diseases (38% versus 0.5%; p < 0.0001). Pruritus, body-lice infestation, scratching lesions, folliculitis, tinea pedis, scabies and impetigo (ecthyma) were strongly significantly associated with homelessness. The higher prevalence of skin infections in the homeless people mainly results from the body-louse infestation, scabies, bacterial super-infection of skin surfaces that have been breached by frequent scratching and tinea pedis due to poor foot hygiene.

Adult↗