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Biomedical subjects

Didier Raoult

Publications and source records attributed to Didier Raoult.

At least 73 records · Page 4Linked to original sources
PubMed2006

No serological evidence for rickettsial diseases among Danish elite orienteerers.

A series of sudden unexpected cardiac deaths among Swedish elite orienteerers in the 1980s have resulted from the combination of infectious diseases and physical exercise. Studies in the late 1990s have pointed to Chlamydia and Barontella, which both had a high seroprevalence among Swedish elite orienteerers. We conducted a case-control study aimed to elucidate the serologic prevalence of rickettsial diseases among Danish elite orienteerers. Ticks are known as vectors for some rickettsial diseases. None of the orienteerers had a positive antibody titer against any of the tested Rickettsia despite a very high frequency of tick bites in this group.

Animals↗
PubMed2006

Prospective evaluation of rickettsioses in the Trakya (European) region of Turkey and atypic presentations of Rickettsia conorii.

In 2004 between the months of May-November, 11 patients with spotted fever group (SFG) rickettsioses were admitted to the Trakya University Hospital in Edirne, Turkey. SFG rickettsioses were diagnosed clinically. Before treatment, punch biopsy from skin lesions, especially from the eschar, was performed. Serum specimens were tested by IFA using a panel of nine rickettsial antigens, including SFG rickettsiae and R. typhi. Western blotting and standard PCR were also performed. The average age of the 11 patients (4 male and 7 female) was 51 years. All the patients had high fever; 10 (91%) had maculopapular rash; 8 (73%) had rash in the palms or on the soles. Five patients had a unique eschar; two had double eschars (64%). Two patients presented with multiple organ failure and one of them died. All the patients had significant antibody titers against SFG rickettsiae. PCR experiments of skin biopsies were positive in six (60%) of 10 skin biopsy samples and DNA sequencing of the positive PCR products gave 100% homology with Rickettsia conorii Malish 7 for opmA and gltA. Trakya Region in an endemic area for rickettsioses. In this series, three patients presented with life-threatening diseases and one of them died. This patient was the first fatal case (2.8%). Atypic and serous life-threatening presentations of rickettsioses must be kept in mind for the differential diagnosis of febrile disease in Turkey.

Boutonneuse Fever↗
PubMed2006

Reemergence of rickettsiosis in Oran, Algeria.

The presumptive cases of Mediterranean spotted fever have been identified in 1993 and since that time, its frequency has steadily increased. The prospective study, in summer 2004, was conducted in order to present the descriptive clinic and epidemiology, to identify more severe forms, the presence of the multiple eschars, and different rickettsial strains caused the disease in our region. In Oran, the cases were diagnosed clinically. In Marseille, serum specimens were tested by IFA using the panel of eight rickettsial antigen; Western blot and cross-adsorption studies were also performed in order to confirm the diagnosis. Ninety-three patients clinically diagnosed were recorded from July 3 to October 28, 2004. Eighty percent were male, the mean age was 44.3 years, 90% were exposed to dog and 32% reported tick bites. Clinical signs were as follow: presence of underlying disease (44%), sudden onset (78%), fever (100%), loss of weight (63%), conjunctivitis (43%), and a tache noire was noticed in 70%. Interestingly, two patients had two and three eschars, respectively. The rash was maculopapular (palm and sole) and purpuric in nine cases. Doxycycline was the most antibiotic (91%) with favourable outcome in 91% of the cases. Malignant form with death is reported for three patients (3.2%). Among the 93 patients, 104 serum from 65 patients were tested (serums of others patients were lost or ticket not found on tube. Sixty-three patients out of 65 had a positive serology by IFA with cross-reactive antibodies especially between R. conorii, R. felis and/or R. typhi. Two others negative serology were: one precocious serum and second from the patient, which presented symptoms of MSF and tested two serums, Western blot and cross-adsorption.

Algeria↗
PubMed2006

Arthropod-borne diseases in homeless.

Homeless people are particularly exposed to ectoparasite. The living conditions and the crowded shelters provide ideal conditions for the spread of lice, fleas, ticks, and mites. Body lice have long been recognized as human parasites and although typically prevalent in rural communities in upland areas of countries close to the equator, it is now increasingly encountered in developed countries especially in homeless people or inner city economically deprived population. Fleas are widespread but are not adapted to a specific host and may occasionally bite humans. Most common fleas that parasite humans are the cat, the rat, and the human fleas, Ctenocephalides felis, Xenopsylla cheopis, and Pulex irritans, respectively. Ticks belonging to the family Ixodidae, in particular, the genera Dermacentor, Rhipicephalus, and Ixodes, are frequent parasites in humans. Sarcoptes scabiei var. hominis is a mite (Arachnida class) responsible for scabies. It is an obligate parasite of human skin. The hematophagic-biting mite, Liponyssoides sanguineus, is a mite of the rat, mouse, and other domestic rodents but can also bite humans. Finally, the incidence of skin disease secondary to infestation with the human bedbug, Cimex lectularius, has increased recently. Bacteria, such as Wolbacchia spp. have been detected in bedbug. The threat posed by the ectoparasite in homeless is not the ectoparasite themselves but the associated infectious diseases that they may transmit to humans. Except for scabies all these ectoparasites are potential vectors for infectious agents. Three louse-borne diseases are known at this time. Trench fever caused by Bartonella quintana (B. quintana), epidemic typhus caused by Rickettsia prowazekii, and relapsing fever caused by the spirochete Borrelia recurrentis. Fleas transmit plague (Xenopsylla cheopis and Pulex irritans), murine typhus (Xenopsylla cheopis), flea-borne spotted rickettsiosis on account of the recently described species Rickettsia felis (C. felis), and occasionally cat scratch disease on account of Bartonella henselae (C. felis). The role of fleas as potential vector of B. quintana has recently been suggested. Among the hematophagic-biting mites, L. sanguineus, is responsible for the transmission of Rickettsia akari, the etiologic agent of rickettsialpox. Virtually, no data are available on tick-borne disease in this population. This article will deal with epidemiology, diagnosis, prevention, and treatment of these ectoparasite and the infectious diseases they transmit to the homeless people.

Animals↗
PubMed2006

First molecular detection of R. conorii, R. aeschlimannii, and R. massiliae in ticks from Algeria.

Ticks collected in Northern Algeria between May 2001 and November 2003 were tested by PCR for the presence of Rickettsia spp. DNA using primer amplifying gltA and OmpA genes. Three different spotted fever group rickettsias were amplified from these ticks: R. Conorii subsp. P. conorii strain Malish in Rhipicephalus sanguineus, R. aeschlimannii in Hyalomma marginatum, and R. massiliae in Rhipicephalus turanicus. Our results confirm the presence of R. conorii in ticks in Algeria and provide the first detection of R. aeschlimannii and R. massiliae in Algeria.

Algeria↗
PubMed2006

Detection of members of the genera Rickettsia, Anaplasma, and Ehrlichia in ticks collected in the Asiatic part of Russia.

A total of 395 adult ixodid ticks from three genera (Dermacentor, Haemaphysalis, and Ixodes) collected from the Urals to the Far East of Russia were tested by PCR and sequencing for the presence of spotted fever rickettsiae, anaplasmae, and ehrlichiae. Four, pathogens recognized in humans were detected in ticks: Rickettsia sibirica, R. heilongjiangensis, R. helvetica, and Anaplasma phagocytophilum. In addition, rickettsiae and ehrlichiae of unknown pathogenicity were detected, including Rickettsia sp. RpA4, Rickettsia sp. DnS14, Rickettsia sp. DnS28, "Candidatus R. tarasevichiae," a rickettsia closely related to R. helvetica, A. bovis, Ehrlichia muris, "Ehrlichia-like" "Schotti variant," and bacterium "Montezuma." Our findings indicated the distribution of rickettsiae and ehrlichiae in hard ticks in Russia.

Anaplasma↗
PubMed2006

Multiplexed serology in atypical bacterial pneumonia.

Atypical pneumonia is a term applied to lower respiratory tract infections that are not characterized by signs and symptoms of lobar consolidation. This article will discuss the epidemiology, clinical manifestations, and laboratory diagnoses of Mycoplasma pneumoniae, Chlamydia sp., Legionella sp., Francisella tularensis, and Coxiella burnetii, which are the agents most commonly associated with atypical pneumonia. Because many of these pathogens are intracellular, diagnosis depends upon serological confirmation. The current serological tests used to identify these agents in the etiologic diagnosis of atypical pneumonia are described. Recently, however, it has become possible to make a diagnosis directly in these cases using DNA or protein microarrays. Here, we describe the development of a new, automated technique for simultaneous testing and detection of several pathogens using a multiplexed serology test. This should prove to be a valuable tool for the rapid determination of patient status, allowing effective and efficient postexposure prophylaxis and treatment.

Atypical Bacterial Forms↗
PubMed2006

Corpuscular antigenic microarray for the serodiagnosis of blood culture-negative endocarditis.

Blood culture-negative endocarditis is due to fastidious bacteria, including Coxiella burnetii and Bartonella spp. Diagnosis of such infection relies on serology and microimmunofluorescence is therefore the reference method. We developed a multiplex serology test featuring automatic incubation and reading and incorporating internal controls. Preliminary results indicate that this new serologic test is valuable for the rapid, automated serological diagnosis of blood culture-negative endocarditis.

Antigens, Bacterial↗
PubMed2006

Proposal to create subspecies of Rickettsia sibirica and an emended description of Rickettsia sibirica.

The Rickettsia sibirica species is composed of isolates that are genotypically close but can be classified within two distinct serotypes, that is, R. sibirica sensu stricto and R. sibirica mongolitimonae (incorrectly named R. mongolotimonae). We investigated the possibility of classifying rickettsiae closely related to R. sibirica as R. sibirica subspecies, as proposed by the ad hoc Committee on Reconciliation of Approaches to Bacterial Systematics. For this, we first estimated the genotypic variability by using multilocus sequence typing (MLST), including the sequencing of five genes, and multispacer typing (MST) using three intergenic spacers, of five isolates and three tick amplicons of R. sibirica sensu stricto and six isolates of R. sibirica mongolotimonae. Then, we selected a representative of each MLST genotype and used mouse serotyping to estimate their degree of taxonomic relatedness. Among the 14 isolates or tick amplicons studied, 2 MLST genotypes were identified: (i) the R. sibirica sensu stricto type; and (ii) the R. sibirica mongolitimonae type. Representatives of the two MLST types were classified within three MST types and into two serotypes. Therefore, as isolates within the R. sibirica species are genotypically homogeneous but show MST genotypic, serotypic, and epidemio-clinical dissimilarities, we propose to modify the nomenclature of the R. sibirica species through the creation of subspecies. We propose the names R. sibirica subsp. sibirica subsp. nov. (type strain = 2-4-6, ATCC VR-541(T)), and R. sibirica subsp. mongolitimonae subsp. nov. (type strain = HA-91, ATCC VR-1526(T)). The description of R. sibirica is emended to accommodate the two subspecies.

Animals↗
PubMed2006

Rickettsia felis infection, Tunisia.

We report, for the first time, serologic evidence of Rickettsia felis and R. aeschlimannii infections acquired in Tunisia from 1998 to 2003. We found that most patients with antibodies against both R. conorii and R. typhi had serologic evidence of R. felis infection.

Humans↗
PubMed2006

Ameba-associated microorganisms and diagnosis of nosocomial pneumonia.

To elucidate the role of ameba-associated microorganisms (AAMs) as etiologic agents of pneumonia, we screened for Legionella spp., Parachlamydia acanthamoeba, Afipia sp., Bosea spp., Bradyrhizobium spp., Mesorhizobium amorphae, Rasbo bacterium, Azorhizobium caulinodans, Acanthamoeba polyphaga mimivirus, and conventional microorganisms in 210 pneumonia patients in intensive-care units by using culture, polymerase chain reaction, and serologic testing. These resulted in 59 diagnoses in 40 patients. AAMs and non-AAMs were implicated in 10.5% of the patients. The infectious agents were identified in 15 patients: Acanthamoeba polyphaga mimivirus, 8; Legionella pneumophila, 3; L. anisa, 1; Parachlamydia sp., 1; Bosea massiliensis, L. worsleiensis, L. quinlivanii, and L. rubrilucens, 1; and M. amorphae and R. bacterium, 1. A. polyphaga mimivirus was the fourth most common etiologic agent, with a higher seroprevalence than noted in healthy controls. This finding suggested its clinical relevance. Therefore, AAM might cause nosocomial pneumonia and should be suspected when conventional microbiologic results are negative.

Acanthamoeba↗
PubMed2006

Bartonella quintana characteristics and clinical management.

Bartonella quintana, a pathogen that is restricted to human hosts and louse vectors, was first characterized as the agent of trench fever. The disease was described in 1915 on the basis of natural and experimental infections in soldiers. It is now recognized as a reemerging pathogen among homeless populations in cities in the United States and Europe and is responsible for a wide spectrum of conditions, including chronic bacteremia, endocarditis, and bacillary angiomatosis. Diagnosis is based on serologic analysis, culture, and molecular biology. Recent characterization of its genome allowed the development of modern diagnosis and typing methods. Guidelines for the treatment of B. quintana infections are presented.

Adult↗
PubMed2006

Rickettsial infections and fever, Vientiane, Laos.

Rickettsial diseases have not been described previously from Laos, but in a prospective study, acute rickettsial infection was identified as the cause of fever in 115 (27%) of 427 adults with negative blood cultures admitted to Mahosot Hospital in Vientiane, Laos. The organisms identified by serologic analysis were Orientia tsutsugamushi (14.8%), Rickettsia typhi (9.6%), and spotted fever group rickettsia (2.6% [8 R. helvetica, 1 R. felis, 1 R. conorii subsp. indica, and 1 Rickettsia "AT1"]). Patients with murine typhus had a lower frequency of peripheral lymphadenopathy than those with scrub typhus (3% vs. 46%, p<0.001). Rickettsioses are an underrecognized cause of undifferentiated febrile illnesses among adults in Laos. This finding has implications for the local empiric treatment of fever.

Adolescent↗