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Hubert Lepidi

Publications and source records attributed to Hubert Lepidi.

At least 37 records · Page 2Linked to original sources
PubMed2005

Q fever pneumonia: virulence of Coxiella burnetii pathovars in a murine model of aerosol infection.

Q fever is a worldwide zoonosis caused by Coxiella burnetii, a strictly intracellular bacterium that is a potential bioweapon. Humans usually acquires Q fever after inhalation of dust infected by subclinical animals. We used an aerosol exposure apparatus to challenge immunocompetent (BALB/c) and severe combined immunodeficient (SCID) mice with two different strains (strain Nine Mile and strain Q 212) of C. burnetii at two different inocula. Pathological lesions and dissemination of the bacteria were related to the size of the inoculum. SCID mice showed major pulmonary lesions, whereas similarly infected BALB/c mice were more able to eliminate the bacteria. Pathological differences were found between the strains, with Nine Mile showing more severe histological lesions and quantified spread of bacteria. Our animal model could provide a new tool for the study of acute Q fever pneumonia, the development of Q fever in immunodeficient hosts, and the differentiation of pathogenicity among C. burnetii isolates.

Aerosols↗
PubMed2005

PCR detection of bacteria on cardiac valves of patients with treated bacterial endocarditis.

We used broad-range PCR amplification and sequencing to detect and identify bacterial DNA in 156 valves of patients treated for infective endocarditis (IE). Bacterial DNA was found more frequently in patients who underwent valve replacement while on antibiotic treatment for IE (60%) than in patients who had completed antibiotic treatment for IE (37%; P = 0.02). We found specific bacterial DNA in valves removed from 11 of 30 patients who had completed antibiotic treatment for IE. Six had no histological evidence of IE. The presence of DNA was significantly correlated with the presence of histologic lesions (P = 0.001) and with the presence of bacteria detected by Gram staining (P < 0.001). Bartonella and streptococci were detected for much longer after antibiotic treatment by PCR than other species (P = 0.047 and 0.04, respectively), and coagulase-negative staphylococci were detected for much shorter periods (P = 0.02). The finding that bacterial DNA was more likely to be detected in valves of patients with active IE than in patients who had completed antibiotic treatment for IE shows that bacterial DNA is cleared slowly. There was no significant correlation between the duration of antibiotic therapy and the presence of bacterial DNA in valves. Since the persistence of bacterial DNA in valves does not necessarily indicate the persistence of viable bacteria, the detection of bacterial DNA in valves from IE patients should be interpreted with caution, in particular in those patients with a past history of treated IE.

Adult↗
PubMed2005

TLR2 is necessary to inflammatory response in Coxiella burnetii infection.

The resolution of Q fever, a zoonosis caused by Coxiella burnetii, depends on efficient innate and adaptive immune responses. Such responses are influenced by Toll-like receptors (TLRs). TLR4 is involved only in part in immune responses against C. burnetii, suggesting a role for TLR2. We investigated C. burnetii infection in wild-type and TLR2(-/-) mice. C. burnetii organisms were similarly eliminated by wild-type and TLR2(-/-) mice. In contrast, the formation of granulomas, a marker for efficient cell-mediated immunity, was markedly impaired. These results show that TLR2 is required for inflammatory and immune response to C. burnetii, but is dispensable for bacterial clearance.

Animals↗
PubMed2005

Bacterial zoonoses and infective endocarditis, Algeria.

Blood culture-negative endocarditis is common in Algeria. We describe the etiology of infective endocarditis in this country. Samples from 110 cases in 108 patients were collected in Algiers. Blood cultures were performed in Algeria. Serologic and molecular analysis of valves was performed in France. Infective endocarditis was classified as definite in 77 cases and possible in 33. Causative agents were detected by blood cultures in 48 cases. All 62 blood culture-negative endocarditis cases were tested by serologic or molecular methods or both. Of these, 34 tested negative and 28 had an etiologic agent identified. A total of 18 infective endocarditis cases were caused by zoonotic and arthropodborne bacteria, including Bartonella quintana (14 cases), Brucella melitensis (2 cases), and Coxiella burnetii (2 cases). Our data underline the high prevalence of infective endocarditis caused by Bartonella quintana in northern Africa and the role of serologic and molecular tools for the diagnosis of blood culture-negative endocarditis.

Adolescent↗
PubMed2004

Cardiac valves in patients with Whipple endocarditis: microbiological, molecular, quantitative histologic, and immunohistochemical studies of 5 patients.

The pathological features of Whipple endocarditis, which is caused by Tropheryma whipplei, were histologically evaluated in cardiac valves from 5 patients. We used quantitative image analysis to compare the valvular fibrosis, calcifications, vegetations, inflammation, and vascularization due to Whipple endocarditis with those due to non-Whipple endocarditis and degenerative valves. We also studied the presence of T. whipplei in valves by immunohistochemical analysis, culture, and polymerase chain reaction (PCR). In histologic analysis, Whipple endocarditis was characterized by significant fibrosis, a lack of calcifications, slight inflammation and vascularization, and vegetations of intermediate size. Inflammatory infiltrates consisted mainly of foamy macrophages and lymphocytes. We found that the detection of T. whipplei in cardiac valves, by immunohistochemical analysis, was correlated with the detection of the bacterium by culture and PCR. We report, for the first time, the immunodetection of T. whipplei in a surgically removed arterial embolus. Pathological and immunohistologic analyses may contribute to the diagnosis of Whipple endocarditis.

Adult↗
PubMed2004

Lipopolysaccharide from Coxiella burnetii is involved in bacterial phagocytosis, filamentous actin reorganization, and inflammatory responses through Toll-like receptor 4.

The role of Toll-like receptors (TLRs) in the recognition of extracellular and facultative intracellular bacteria by the innate immune system has been extensively studied, but their role in the recognition of obligate intracellular organisms remains unknown. Coxiella burnetii, the agent of Q fever, is an obligate intracellular bacterium that specifically inhabits monocytes/macrophages. We showed in this study that C. burnetii LPS is involved in the uptake of virulent organisms by macrophages but not in that of avirulent variants. The uptake of virulent organisms was dependent on TLR4 because it was reduced in macrophages from TLR4(-/-) mice. In addition, LPS was responsible for filamentous actin reorganization induced by virulent C. burnetii, which was prevented in TLR4(-/-) macrophages. In contrast, the intracellular fate of C. burnetii was not affected in TLR4(-/-) macrophages, suggesting that TLR4 does not control the maturation of C. burnetii phagosome and the microbicidal activity of macrophages. These results are consistent with in vivo experiments because the pattern of tissue infection and the clearance of C. burnetii were similar in wild-type and TLR4(-/-) mice. We also showed that the number of granulomas was decreased in the liver of infected TLR4(-/-) mice, and the formation of splenic granulomas was only transient. The impaired formation of granulomas was associated with decreased production of IFN-gamma and TNF. Taken together, these results demonstrate that TLR4 controls early events of C. burnetii infection such as macrophage phagocytosis, granuloma formation, and cytokine production.

Actins↗
PubMed2004

Effect of sex on Coxiella burnetii infection: protective role of 17beta-estradiol.

Q fever is a zoonosis caused by Coxiella burnetii and recently has been recognized as a potential agent of bioterrorism. In Q fever, men are symptomatic more often than women, despite equal seroprevalence. We hypothesized that sex hormones play a role in the pathogenesis of C. burnetii infection. When C57/BL6 mice were injected with C. burnetii, bacteria load and granuloma numbers were lower in females than in males. Ovarectomized mice showed increased bacteria load in the spleen and the liver, similar to that found in males. The granuloma number was also increased in ovarectomized mice and reached the levels found in males. Tissue infection and granulomatous response are largely under the control of estrogens: treatment of ovarectomized mice with 17beta-estradiol reduced both bacteria loads and granuloma numbers. These results show that sex hormones control host response to C. burnetii infection and may account for host-dependent clinical presentation of Q fever.

Animals↗
PubMed2004

Pathogenic role of P-selectin in experimental cerebral malaria: importance of the endothelial compartment.

P-selectin is a leukocyte adhesion receptor expressed on the surface of activated platelets and endothelial cells. Its role in the pathogenesis of cerebral malaria was explored in a murine model of cerebral malaria. Infection of mice with Plasmodium berghei ANKA led to P-selectin up-regulation in brain vessels of cerebral malaria-susceptible mice but not of cerebral malaria-resistant mice. Treatment of susceptible mice with anti-mouse P-selectin mAb failed to prevent the development of the neurological syndrome. However, P-selectin-deficient mice infected with Plasmodium berghei ANKA had a cumulative incidence of cerebral malaria which was significantly reduced compared to wild-type animals (4.5% versus 80%, respectively), despite identical levels of parasitemia, platelet and leukocyte accumulation. To determine whether P-selectin on platelets and/or endothelium was responsible for the microvascular pathology, cerebral malaria was assessed in chimeric mice deficient in platelet or endothelial P-selectin, which were generated by bone marrow transplantation. Mice deficient only in endothelial P-selectin did not show any sign of cerebral malaria (vascular plugging, hemorrhages, or edema), while mice lacking only platelet P-selectin showed signs of cerebral malaria similar to that seen in wild-type mice. These results indicate that endothelial P-selectin plays an important role in the pathogenesis of cerebral malaria.

Animals↗
PubMed2004

Intraocular detection of Bartonella henselae in a patient with HLA-B27 uveitis.

Bartonella henselae uveitis was diagnosed in a 40-year-old woman with underlying HLA-B27 uveitis on the basis of immunodetection and molecular detection of the organism, a Marseilles genogroup and a CAL-1 genotype strain, in the vitreous fluid. This case illustrates that B. henselae should be included in the differential diagnosis of uveitis and the usefulness of immunodetection for rapid and specific diagnosis.

Adult↗
PubMed2004

Vanin-1(-/-) mice show decreased NSAID- and Schistosoma-induced intestinal inflammation associated with higher glutathione stores.

Vanin-1 is a membrane-anchored pantetheinase highly expressed in the gut and liver. It hydrolyzes pantetheine to pantothenic acid (vitamin B5) and the low-molecular-weight thiol cysteamine. The latter is believed to be a key regulating factor of several essential metabolic pathways, acting through sulfhydryl-disulfide exchange reactions between sulfhydryl groups of the enzymes and the oxidized form, cystamine. Its physiological importance remains to be elucidated, however. To explore this point, we developed Vanin-1-deficient mice that lack free cysteamine. We examined the susceptibility of deficient mice to intestinal inflammation, either acute (NSAID administration) or chronic (Schistosoma infection). We found that Vanin-1(-/-) mice better controlled inflammatory reaction and intestinal injury in both experiments. This protection was associated with increased gamma-glutamylcysteine synthetase activity and increased stores of reduced glutathione, as well as reduced inflammatory cell activation in inflamed tissues. Oral administration of cystamine reversed all aspects of the deficient phenotype. These findings suggest that one cysteamine function is to upregulate inflammation. Consequently, the pantetheinase activity of Vanin-1 molecule could be a target for a new anti-inflammatory strategy.

Amidohydrolases↗
PubMed2003

Mycoplasma endocarditis: two case reports and a review.

We describe 2 patients with endocarditis for whom blood cultures and cardiac valve cultures were repeatedly sterile. Broad-range eubacterial polymerase chain reaction (PCR) amplification performed on cardiac valve specimens from these 2 patients detected DNA of Mycoplasma hominis, for one patient, and of Ureaplasma parvum, for the other patient. Three other cases of infective endocarditis caused by mycoplasmas were identified in the literature. It is important to rule out a diagnosis of mycoplasma endocarditis because the evolution of the disease may be fatal and it requires an adequate and specific antibiotic therapy.

Adult↗
PubMed2003

Whipple disease associated with giardiasis.

We tested 53 fixed duodenal biopsy samples from 25 patients with Whipple disease for the presence Giardia and 6 fresh duodenal biopsy samples for Giardia duodenalis DNA by polymerase chain reaction (PCR). We also used histological examination and PCR assay to determine the prevalence of G. duodenalis in duodenal biopsy samples from 150 control patients without Whipple disease. Three of 25 patients with Whipple disease had histological evidence of giardiasis, whereas only 1 of 150 control patients was affected (P<.001). By PCR, we found Giardia in 2 of 6 patients with Whipple disease whom we tested, but in only 2 of 150 control patients (P<.001). In a literature review, we identified 15 other cases of coinfection. The occurrence of these diseases may be promoted by a common immune defect or a common source of infection, or infection with one may predispose to infection with the other.

Actinomycetales↗
PubMed2003

Cardiac valves in patients with Q fever endocarditis: microbiological, molecular, and histologic studies.

The pathologic features of Q fever endocarditis, which is caused by Coxiella burnetii, were histologically evaluated in cardiac valves from 28 patients. We used quantitative image analysis to compare valvular fibrosis, calcifications, vegetations, inflammation, and vascularization due to Q fever endocarditis with that due to non-Q fever endocarditis and valvular degeneration. We also studied the presence of C. burnetii in valves by immunohistochemical analysis, culture, and polymerase chain reaction (PCR). Histologically, Q fever endocarditis was characterized by significant fibrosis and calcifications, slight inflammation and vascularization, and small or absent vegetations. Despite antibiotic treatment, non-statistically significant variations at the histologic level were observed. These pathologic features could be confused with noninfectious valvular degenerative damage. We found that the detection of C. burnetii in cardiac valves by immunohistochemical analysis, culture, and PCR decreased significantly only after 1 year of antibiotic treatment, which emphasizes the long persistence of this organism in valve tissues. Pathologic and immunohistochemical analyses may contribute to the diagnosis of Q fever endocarditis.

Adult↗
PubMed2003

Whipple's disease: immunospecific and quantitative immunohistochemical study of intestinal biopsy specimens.

Whipple's disease may be diagnosed by periodic acid-Schiff (PAS) staining, electron microscopy, or polymerase chain reaction of intestinal biopsy specimens. The aim of this study was to evaluate the diagnostic value of immunohistochemistry and the quantification of infected cells in intestinal Whipple's disease. A total of 29 duodenal biopsy specimens from 15 patients with untreated and treated Whipple's disease were examined and compared with biopsy specimens from control patients with normal intestinal mucosa or various pathologic processes. Percentages of staining surfaces with PAS stain and antibodies directed against CD68, a macrophage marker, or the Whipple bacillus, Tropheryma whipplei, were studied quantitatively using a computerized system of image analysis. Positive detection of T. whipplei was obtained using immunohistochemistry in all 15 patients with Whipple's disease. No bacteria were detected in any of the negative controls. The use of quantitative image analysis showed a massive intestinal macrophagic infiltration before (20.3%) and after (13.4%) antibiotic therapy completion as compared with controls (2.1%). The 2 detection methods for T. whipplei, PAS stain and immunohistochemistry, were quantitatively similar before therapy (19.9% versus 17.5%), but the immunodetection-based surface area was significantly lower than the PAS staining surface area after therapy (2.8% versus 7.9%). Our findings indicate that immunohistochemistry is highly specific and sensitive and is applicable as a diagnostic method on intestinal tissue specimens to detect T. whipplei during active infection or in retrospective studies.

Actinobacteria↗
PubMed2003

Molecular diagnosis of infective endocarditis by PCR amplification and direct sequencing of DNA from valve tissue.

We used broad-range eubacterial PCR amplification followed by direct sequencing to identify microbial pathogens in heart valve material from 29 patients with histologically confirmed infective endocarditis and 23 patients free of infective endocarditis. Microorganisms cultured by conventional techniques matched those identified by PCR in 21 cases. PCR alone identified the causative agent in three cases (Streptococcus bovis, Staphylococcus cohnii, and Coxiella burnetii), allowing better patient management. PCR corrected the initial bacteriological diagnosis in three cases (Streptococcus bovis, Streptococcus mutans, and Bartonella henselae). Among the 29 cases of histologically confirmed infective endocarditis, PCR findings were positive in 27 cases and were consistent with the bacterial morphology seen at Gram staining (26 cases) or with the results obtained by immunohistologic analysis with an anti-C. burnetii monoclonal antibody (one case). In two other cases of histologically confirmed infective endocarditis, PCR remained negative in a blood culture-negative case for which no bacteria were seen at histological analysis and in one case with visualization of cocci and blood cultures positive for Enterococcus faecalis. Ten clinical diagnoses of possible infective endocarditis were ruled out by histopathological analysis of the valves and subsequently by PCR. PCR was negative in 13 of the 14 patients in whom infective endocarditis was rejected on clinical grounds; the other patient was found to have Coxiella burnetii infective endocarditis on the basis of PCR and histopathological analysis and was subsequently included in the group of 29 definite cases. In total, PCR contributed to the diagnosis and management of infective endocarditis in 6 of 29 (20%) cases.

DNA, Bacterial↗
PubMed2002

An experimental model of human body louse infection with Rickettsia prowazekii.

Rickettsia prowazekii is transmitted to humans by the body louse. A new experimental model of body louse infection with R. prowazekii is reported here. Eight hundred human lice were infected by feeding on a rabbit that was made bacteremic by injecting 2x106 plaque-forming units of R. prowazekii. The bacterium invaded the stomach cells and was released in feces, in which it was detected 5 days after infection. At day 6 after infection, as a result of the cell burst and the spread of erythrocytes in the hemolymph, the louse became bright red and died within 4 h. The life span of infected lice was shortened by 20-23 days, compared with that of uninfected control lice. Infected lice did not transmit R. prowazekii to their progeny. Through cell culture, rickettsiae were cultivated from fecal samples up to 10 days after their emission. The administration of doxycycline to the rabbit during louse feeding did not cure lice from R. prowazekii infection.

Animals↗