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Biomedical subjects

D Raoult

Publications and source records attributed to D Raoult.

At least 307 records · Page 17Linked to original sources
PubMed1996

Modification of the diagnostic criteria proposed by the Duke Endocarditis Service to permit improved diagnosis of Q fever endocarditis.

BACKGROUND: Q fever endocarditis is a life-threatening disease for which the diagnosis is usually based on serology. The major microbiologic criterion for the diagnosis of infectious endocarditis (two separate positive blood cultures) cannot be achieved in most routine laboratories because of the biohazard associated with the culture of Coxiella burnetii, the etiological agent of Q fever. PURPOSE: Recently, new criteria for the diagnosis of infectious endocarditis have been proposed, and in this study we attempted to assess the suitability of these criteria specifically for the diagnosis of Q fever endocarditis. PATIENTS AND METHODS: To achieve this aim, we first selected from our series 20 recent cases in whom endocarditis had been confirmed following valvular pathological examination, and for whom microbiological evidence for the involvement of C burnetii was available. Then, we applied the criteria proposed by the Duke Endocarditis Service (ie, C burnetii positive serology being considered a minor criterion) to this cohort of patients but excluding pathological findings. Although the Duke Endocarditis Service criteria confirmed diagnosis in 16 of the patients, 4 were misclassified as "possible" cases (20%). However, when the Q fever serological results (using an 1/800 antiphase I immunoglobulin G cut off) and single blood culture results were changed from minor to major diagnostic criteria, endocarditis was confirmed in them all. A second time, prospectively, we applied the Duke Endocarditis Service criteria to a further 5 patients affected with Q fever endocarditis. Strict application of these criteria resulted in 1 of the 5 being misdiagnosed. Applying the suggested modification for C burnetii results, all 5 were confirmed as having infectious endocarditis. CONCLUSION: We propose that the modifications discussed in this study be applied to the Duke Endocarditis Service criteria in order that the diagnosis of C burnetii induced endocarditis is improved.

Coxiella burnetii↗
PubMed1996

Mycoplasma pneumoniae pneumonia following assisted ventilation.

BACKGROUND: Mycoplasma pneumoniae pneumonia is regarded as a community-acquired pneumonia, rarely requiring hospitalization, with sporadic cases or limited outbreaks occurring after close contacts with an infected patient. Few reports mention M pneumoniae pneumonia acquired during hospitalization. PATIENTS AND METHODS: M pneumoniae was diagnosed in patients who developed pneumonia following perioperative and postoperative assisted ventilation by the isolation of M pneumoniae from bronchial washing, the detection of M pneumoniae DNA from bronchial washing, and serologic testing for the presence of specific immunoglobulin M (IgM) antibodies. RESULTS: Four patients were diagnosed as having M pneumoniae pneumonia following mechanical ventilation over a 1 1/2-year period. They were men, older than 50 years, and were hospitalized for vascular surgery. They developed febrile hypoxemia and intersticial pneumonia. Isolation of M pneumoniae and detection of M pneumoniae DNA were positive in 1 case; specific IgM antibodies were present in 4 cases. CONCLUSIONS: These observations allow the description of a new clinical entity and highlight the role of M pneumoniae as an agent of nosocomial infections. This diagnosis should be considered in any patient with precocious post-assisted ventilation febrile hypoxemia and diffuse interstitial pneumonia, and empiric treatment protocols may include M pneumoniae in their spectrum.

Aged↗
PubMed1996

Survey of the seroprevalence of Bartonella quintana in homeless people.

Trench fever is caused by Bartonella (Rochalimaea) quintana, a small gram-negative rod that is transmitted by body lice. Recently, B. quintana infections in homeless patients have been reported in the United States and Europe. From October 1993 to October 1994, the seroprevalence of antibodies to B. quintana was assessed by indirect immunofluorescence in a prospective study of 221 nonhospitalized homeless people, 43 hospitalized homeless patients (cases), 250 blood donors, and 57 hospitalized matched controls. Four (1.8%) of 221 nonhospitalized homeless people tested had titers of > 1:100. Of the 43 cases, seven (16%) had serological titers of > or = 1:100. None of the 250 serum samples from blood donors contained antibodies to B. quintana. The presence of antibodies to B. quintana in cases was significantly associated with the presence of body lice, exposure to cats, headaches, eastern European origin, and pain in the legs. This study demonstrates the presence of antibodies to B. quintana in the homeless population and should alert physicians that B. quintana might be an etiologic agent of fever in homeless patients.

Animals↗
PubMed1996

Route of infection determines the clinical manifestations of acute Q fever.

In Nova Scotia the main manifestation of acute Q fever is pneumonia, while in France it is granulomatous hepatitis. To test the hypothesis that the route of infection is the major determinant of the manifestations of acute Q fever, 10 groups of 10- to 12-g female BALB/c mice (4 animals/group) were used. Five groups were inoculated intraperitoneally (ip) and 5 intranasally (inl) with Coxiella burnetii. Both routes of infection resulted in pneumonia. However, the inl route resulted in greater airway changes (on a numeric scale with 0 being no changes): 2.05 +/- 2.20 versus 0.60 +/- 0.83 (P < .002). The ip route resulted only in hepatosplenomegaly. It was concluded that the route of infection is one determinant of the manifestations of acute Q fever.

Animals↗
PubMed1996

Rickettsia africae sp. nov., the etiological agent of African tick bite fever.

We propose the name Rickettsia africae sp. nov. (with type strain Z9-Hu) for a distinct species of spotted fever group (SFG) rickettsiae that is the etiological agent of African tick bite fever in humans. This rickettsia has a distinct natural cycle and can be phenotypically distinguished from the other SFG rickettsiae by microimmunofluorescence serotyping, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and by Western blotting (immunoblotting). Genotypic differences between R. africae and the other SFG rickettsiae can be demonstrated by PCR restriction fragment length polymorphism analysis, pulsed-field gel electrophoresis, and sequencing of the 16S rRNA gene.

Africa↗
PubMed1996

Phylogenesis of relapsing fever Borrelia spp.

The phylogenetic relationships of 20 relapsing fever (RF) Borrelia spp. were estimated on the basis of the sequences of rrs genes. Complete sequences were aligned and compared with previously published sequences, and the similarity values were found to be 97.7 to 99.9%. Phylogenetic trees were constructed by using the three neighbor-joining, maximum-parsimony, and maximum-likelihood methods. The results of the comparative phylogenetic analysis divided the RF Borrelia spp. into three major clusters. One cluster included Borrelia crocidurae, Borrelia duttonii, Borrelia recurrentis, and Borrelia hispanica. Another cluster comprised tow main branches with Borrelia coriaceae, Borrelia lonestari, and Borrelia miyamotoi on one side and Borrelia parkeri, Borrelia turicatae, and Borrelia hermsii on the other side. Borrelia anserina constituted the third cluster. The phylogenetic position of Borrelia persica was more uncertain. These results suggested that the taxonomy of these spirochetes should be revised. To overcome the problems of culturing the spirochetes, RF Borrelia primers were defined. Following PCR amplification of the rrs gene, restriction length fragment polymorphism could be used to distinguish between RF Borrelia strains.

Animals↗
PubMed1996

Comparison of partial citrate synthase gene (gltA) sequences for phylogenetic analysis of Bartonella species.

Nucleotide base sequence data were obtained for a 940-bp fragment of the citrate synthase-encoding gene (gltA) of representatives of the eight validly described Bartonella species and seven uncharacterized Bartonella strains obtained from small mammals. Complete 16S rRNA gene sequences were also determined for the uncharacterized strains, and these sequences revealed that each strain had a unique sequence which was very similar to the sequences of the previously recognized Bartonella species. A comparison of the gltA sequences of the different Bartonella species revealed that the levels of similarity between sequences were 83.8 to 93.5%, whereas comparisons of sequences obtained from different strains of the same species revealed that the levels of similarity were more than 99.8%. One of the uncharacterized strains had a gltA sequence that matched the sequence of Bartonella elizabethae, three uncharacterized strains had sequences which were more than 99.6% similar to each other (but less than 93.5% similar to any other sequence), and the remaining three uncharacterized strains each exhibited less than 93.5% sequence similarity to other Bartonella species or isolates. Phylogenetic trees were inferred from multiple alignments of both gltA and 16S ribosomal DNA (rDNA) sequences. Whereas the proposed intra-Bartonella architecture of trees inferred from 16S rDNA sequence data by using both distance matrix and parsimony methods had virtually no statistical support, the trees inferred from the gltA sequence data contained four well-supported lineages in the genus. The gltA-derived phylogeny appears to be more useful than the phylogeny derived from 16S rDNA sequence data for investigating the evolutionary relationships of Bartonella species, and the validity of the lineages identified by the gltA analysis is discussed in this paper.

Bartonella↗
PubMed1996

Phylogenetic diversity of intra-amoebal legionellae as revealed by 16S rRNA gene sequence comparison.

Following a recent phylogenetic analysis of all 39 species of the genus Legionella and related organisms, the name Legionella lytica has been proposed for bacteria previously considered either as Sarcobium lyticum or as 'Legionella-like amoebal pathogens' (LLAPs). To investigate the phylogenetic integrity of this newly proposed species, we determined the 16S rRNA gene sequences of 10 LLAPs isolated from various environmental sources. All 10 isolates clustered within a monophyletic group containing all other members of the genus Legionella. Eight of the 10 isolates formed a monophyletic subgroup within the genus which also included the two previously characterized L. lytica strains. Four of these 10 isolates shared a specific and very close relationship with the L. lytica type strain (> 99% sequence similarity). However, although clearly legionellae, the remaining two LLAP strains bore no specific evolutionary relationship to either L. lytica or any other Legionella species (< 96% sequence similarity). Both isolates lay on their own relatively deep-rooted branches within the radiation of the Legionella cluster. LLAPs do not, therefore, represent a unique species or even a single line of descent within the genus, and investigation of more isolates may reveal them to be as evolutionarily diverse as the other presently recognized Legionella species.

Acanthamoeba↗
PubMed1996

Sequence of quinolone resistance-determining region of gyrA gene for clinical isolates and for an in vitro-selected quinolone-resistant strain of Coxiella burnetii.

We report the sequence of the quinolone resistance-determining region of the gyrA genes of either susceptible or low-level-resistant clinical isolates of Coxiella burnetii. The sequences of low-level (MICs, 4 micrograms/ml) and high-level (MICs, 8 and 16 micrograms/ml) resistant strains stepwise selected in vitro were also determined. The gene sequences of all of the clinical isolates and that of the in vitro-selected low-level-resistant strain were identical. Sequence analysis of the in vitro-selected high-level-resistant strain revealed a nucleotide mutation leading to an amino acid substitution of Gly in place of Glu at position 87 of the GyrA amino acid sequence. These results indicate that high-level resistance to ciprofloxacin is associated with a nucleotide mutation in gyrA, whereas low-level resistance to quinolones is not.

Amino Acid Sequence↗
PubMed1996

Eucaryotic cells protect Borrelia burgdorferi from the action of penicillin and ceftriaxone but not from the action of doxycycline and erythromycin.

Despite appropriate antibiotic treatment, Lyme disease patients may have relapses or may develop chronic manifestations. The intracellular location of Borrelia burgdorferi suggests that antibiotics that penetrate cells will have greater efficiency. Doxycycline or erythromycin was more effective than penicillin or ceftriaxone in killing B. burgdorferi when the organism was grown in the presence of eucaryotic cells.

Anti-Bacterial Agents↗
PubMed1996

Bartonella (Rochalimaea) quintana infections.

Bartonella (formerly Rochalimaea) quintana is the etiological agent of trench fever, a disease extensively reported during the World Wars. Recent molecular biology approaches have allowed dramatic extension of the spectrum of Bartonella infections. B. quintana is now also recognized as an etiological agent of fever and bacteremia, endocarditis, bacillary angiomatosis, and chronic lymphadenopathy. Human immunodeficiency virus-infected patients and/or homeless people are the most vulnerable to infection. Poverty and louse infestation were the main epidemiological factors associated with B. quintana infections during wartime. Although poverty and chronic alcoholism have been associated with modern cases of trench fever and bacteremia due to B. quintana in Europe and the United States, vectors for B. quintana have not been clearly identified and B. quintana has not been isolated from modern-day lice. Microscopic bacillary angiomatosis lesions are characterized by tumor-like capillary lobules, with proliferating endothelial cells. In vitro experiments have shown that B. quintana survives within endothelial cells and stimulates cell proliferation. These observations, together with the finding that lesions may regress when antibiotic therapy is administered, strongly suggest that B. quintana itself stimulates angiogenesis. Bartonella infections are characterized by a high frequency of relapses after brief courses of antibiotic therapy. It is to be noted that in vitro, although Bartonella species are highly susceptible to antibiotics, only the aminoglycosides have proved to be bactericidal. However, the most effective antibiotic regimen for Bartonella infections remains to be established.

Angiomatosis, Bacillary↗
PubMed1996

Production of interleukin-10 and transforming growth factor beta by peripheral blood mononuclear cells in Q fever endocarditis.

The pathophysiology of Q fever endocarditis is characterized by the suppression of antigen-specific cell-mediated immune responses. We investigated the production of interleukin-10 (IL-10) and transforming growth factor beta (TGF-beta), known to interfere with the development of protective cell immunity. IL-10 was markedly released by unstimulated peripheral blood mononuclear cells (PBMC) from patients with Q fever endocarditis. This release resulted from the upregulation of IL-10 gene transcription. Similarly, the release of TGF-beta1 and TGF-beta2 was significantly higher in patient PBMC than in control cells, but the expression of their respective mRNA was not enhanced in patient cells. In contrast, lipopolysaccharide-stimulated transcription and release of IL-10 and TGF-beta were similar in patients and controls. The release of IL-10 by PBMC but not that of TGF-beta was correlated with the clinical status of the patients. First, IL-10 production was correlated with specific antibody levels. Second, IL-10 release remained elevated in patients prone to relapse. Taken together, our results suggest that the release of IL-10 and TGF-beta is upregulated in Q fever endocarditis. IL-10 might be considered as a marker of disease relapses and might be instrumental in monitoring the efficiency of the treatment.

Adult↗
PubMed1996

Upregulation of tumor necrosis factor alpha and interleukin-1 beta in Q fever endocarditis.

The occurrence of Q fever endocarditis likely involves some alterations in the responses of monocytes, the in vivo targets of Coxiella burnetii. To test this hypothesis, the production of the inflammatory cytokines tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 was assessed in monocytes from patients with Q fever endocarditis. Spontaneous transcription and secretion of tumor necrosis factor and interleukin-1 were significantly higher in patient monocytes than in healthy controls. The interleukin-6 transcripts were also upregulated in patient cells. Moreover, in patients with recent endocarditis exhibiting high titers of immunoglobulin G directed to C. burnetii in phase I, monocytes released significantly higher levels of tumor necrosis factor and interleukin-1 than in patients with stabilized endocarditis. Immunoglobulin G titers and the overproduction of tumor necrosis factor and interleukin-1 were significantly correlated. Hence, the overproduction of inflammatory cytokines might be a marker of disease activity.

Adult↗
PubMed1996

Phenotypic and genotypic characterization of spotted fever group Rickettsiae isolated from Catalan Rhipicephalus sanguineus ticks.

Eighty-nine Rhipicephalus sanguineus ticks and 21 Rhipicephalus bursa ticks collected in Catalonia were tested by the hemolymph test to establish their infection rate with spotted fever group rickettsiae. By Giménez staining, 11.2% of the R. sanguineus isolates and 0% of the R. bursa isolates were found to contain rickettsia-like organisms. Six spotted fever group rickettsial strains (Bar29, Bar31, Gir4, Tar1, Tar2, and Tar3) were isolated from these ticks and were characterized by phenotypic and genotypic analyses. PCR followed by restriction fragment length polymorphism analysis showed that the six strains were identical and were characterized by the same restriction profiles as a strain, Mtu5, previously isolated from Rhipicephalus turanicus ticks in the South of France. Microimmunofluorescence serotyping, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified organisms, and Western blot (immunoblot) assay with mouse polyclonal sera confirmed this observation. Pulsed field gel electrophoresis of the whole genome of three of the strains showed that, although closely related, the profile of Tar1 was slightly different from that of the Bar strains. Phylogenetic analysis showed that this new rickettsial sero- and genotype, which will be named the "Catalan strain," is closely related to Rickettsia massiliae. This strain shows an unexpected resistance to rifampin. The epidemiological implications of these findings are considered.

Animals↗
PubMed1996

Diagnosis of Mediterranean spotted fever by cultivation of Rickettsia conorii from blood and skin samples using the centrifugation-shell vial technique and by detection of R. conorii in circulating endothelial cells: a 6-year follow-up.

Rickettsia conorii, an obligate intracellular bacterium that infects vascular endothelial cells, is the etiologic agent of Mediterranean spotted fever. We correlated the results of 205 R. conorii blood and skin cultures for 157 patients and the results of 48 detections of R. conorii in circulating endothelial cells (CEC) for 41 patients with relevant serological, clinical, and therapeutic data. R. conorii was cultured from 40% of patients and 29.8% of samples. R. conorii was detected in CEC in 50% of samples, representing 46.2% of patients. When these calculations were limited to the samples from untreated patients prior to their seroconversion to R. conorii, the sensitivity of culture was 59%, whereas it remained at 50% for detection in CEC. We also performed PCRs for the detection of R. conorii on eight shell vial supernatants from positive cultures and on 43 blood samples. Only nonfrozen supernatants from fresh cultures were positive. The methods described in this report are suitable for use in all laboratories. Our findings suggest that for samples to be suitable for culture they must be collected prior to the initiation of an antibiotic regimen, as early as possible in the course of the disease, and be inoculated onto shell vials with minimal delay, if R. conorii is to be successfully isolated. For patients who have been treated or who have a delayed diagnosis, detection of R. conorii in CEC remains helpful.

Antigens, Bacterial↗
PubMed1996

Bartonella (Rochalimaea) quintana infection in a seronegative hemodialyzed patient.

Bartonella quintana is a reemerging pathogen responsible for trench fever, endocarditis, bacteremia, and bacillary angiomatosis. We previously reported the first case of a patient with B. quintana-induced chronic adenomegaly, and here we present a report on a second patient. A hemodialyzed patient with Sjögren's syndrome presented with mediastinal adenomegalies and secondary pancytopenia. All diagnostic investigations remained negative, except that a Bartonella-like microorganism was isolated from a bone marrow biopsy. The isolate was identified as B. quintana by a specific mouse polyclonal antibody and by determination of a partial gltA (citrate synthase-encoding) gene and 16S rRNA gene sequences. DNA of the pathogen was also detected in the adenomegaly and in the serum of the patient by PCR amplification of the gltA gene. Anti-B. quintana antibodies were never detected in the patient's serum throughout the 12-month follow-up but were detected in the serum of the patient's cat. The patient's outcome was favorable after treatment with gentamicin. Chronic adenomegaly in seronegative patients is a new clinical entity due to B. quintana.

Adult↗