PubMed Health⌕ Search

Biomedical subjects

Bruno B Chomel

Publications and source records attributed to Bruno B Chomel.

At least 37 records · Page 2Linked to original sources
PubMed2004

A family of variably expressed outer-membrane proteins (Vomp) mediates adhesion and autoaggregation in Bartonella quintana.

Bartonella species are fastidious, Gram-negative human pathogens that can persist in the host bloodstream for years and bind to and invade several types of host cells. For many pathogens, adhesion to host cells and extracellular matrix (ECM) components is a critical virulence determinant. Bacteria often vary expression of surface adhesins by phase or antigenic variation to subvert the host immune response and permit adaptive interaction with different host structures. We developed a macaque animal model for Bartonella quintana infection to detect changes in bacterial outer-membrane proteins (OMP) during prolonged bloodstream infection. We identified a gene family encoding four highly conserved, 100-kDa, variably expressed OMP (Vomp), two of which function as adhesins. The variable expression of Vomp family members appears to be mediated by deletion of one or more vomp genes during chronic bloodstream infection. vomp deletion was observed also in isolates from humans with chronic B. quintana infection. The Vomp are closely related to the afimbrial adhesin, YadA, a virulence factor of Yersinia enterocolitica. The surface-expressed Vomp contain conserved structural features of YadA, including collagen-binding motifs. We demonstrate that the B. quintana Vomp are multifunctional OMP involved in binding to collagen and autoaggregation: VompC confers the ability to bind collagen IV, and VompA is necessary and sufficient for autoaggregation. The B. quintana Vomp are members of the newly recognized family of YadA-like trimeric autotransporters; the Vomp constitute a multigene family, they are variably expressed, and different virulence properties are attributable to individual Vomp family members.

Adhesins, Bacterial↗
PubMed2004

Seroprevalence of Toxoplasma gondii in American free-ranging or captive pumas (Felis concolor) and bobcats (Lynx rufus).

Toxoplasma gondii is a major zoonotic agent infecting a wide range of mammals, including wild felids. Like domestic cats, wild felids are involved in the complete infective cycle of T. gondii, as they can host in their gastrointestinal tract sexually mature parasites and shed infective oocysts in their feces. In order to evaluate the importance of this wildlife reservoir, 438 serum samples collected between 1984 and 1999 from 438 pumas (Felis concolor) and from 58 bobcats (Lynx rufus) from North America, Central America and South America were screened for antibodies to T. gondii. The overall prevalence of T. gondii antibodies was 22.4% in pumas and 51.7% in bobcats, with regional variations. Adults were more likely to be seropositive than juveniles and kittens (prevalence ratio (PR) = 2.61; confidence interval (CI) = 1.15, 4.04). In the US, pumas from the southwestern states (Arizona, California and New Mexico) were more likely to be seropositive for T. gondii ( PR = 2.61; 95% CI = 1.32-5.18 ) than pumas from the northwestern and mountain states (Colorado, Idaho, Oregon, Utah and Wyoming). Male pumas from the US were more likely to be seropositive than females (PR = 2.08; 95% CI = 1.11-3.92), whereas female pumas from Mexico, Central America and South America were more likely to be seropositive than female pumas from Canada and the US (PR = 2.49; 95% CI = 1.09-5.69). Captive pumas were also more likely to be seropositive (21.7%, 29/92) for T. gondii than free-ranging animals (19.9%, 69/346) (PR = 1.85; 95% CI = 1.06, 3.17).

Animals↗
PubMed2004

Bartonella spp. DNA associated with biting flies from California.

Bartonella DNA was investigated in 104 horn flies (Haematobia spp.), 60 stable flies (Stomoxys spp.), 11 deer flies (Chrysops spp.), and 11 horse flies (Tabanus spp.) collected on cattle in California. Partial sequencing indicated B. bovis DNA in the horn fly pool and B. henselae type M DNA in one stable fly.

Animals↗
PubMed2003

Infection and re-infection of domestic cats with various Bartonella species or types: B. henselae type I is protective against heterologous challenge with B. henselae type II.

Four Bartonella species have been isolated from domestic cats, of which two serotypes/genotypes of Bartonella henselae and possibly B. clarridgeiae are human pathogens, causing cat scratch disease (CSD).Our objectives were to evaluate infection and potential cross-protection during re-infection in domestic cats with various Bartonella species or types.Thirty-six cats were primarily inoculated with B. henselae type I (n=16), B. henselae type II (n=10), B. clarridgeiae (n=6) or B. koehlerae (n=4). They were challenged with B. henselae type I (n=15), B. henselae type II (n=13) or B. clarridgeiae (n=8). All 36 cats became bacteremic (1.25x10(2)-1.44x10(6)CFU/ml) and bacteremia lasted from 37 to 582 days. Duration of bacteremia for cats inoculated with B. henselae type I was shorter than for cats inoculated with either B. henselae type II (P=0.025) or B. clarridgeiae (P=0.011). After challenge, 26 cats became bacteremic. Among the nine cats primarily inoculated with B. henselae type I and challenged with B. henselae type II, six cats stayed abacteremic. The three bacteremic cats had a transient low-level bacteremia. No bacteremia was observed in three cats primarily inoculated with B. henselae type I and challenged with another strain of B. henselae type I. Bacteremia levels in the 26 cats were significantly lower than for primary inoculation (P=0.022) and its duration was shorter (P=0.012). Among the eight cats challenged with B. clarridgeiae, duration of bacteremia in the four cats primarily inoculated with B. henselae type I was shorter than in the four cats primarily inoculated with B. henselae type II (P=0.01). Bartonella clarridgeiae inoculated cats were more likely to have relapses for both primary and secondary infections. This is the first demonstration of cross-protection, evidenced by absence of bacteremia, in cats primarily infected with B. henselae type I and challenged with B. henselae type II, whereas no cross-protection was previously shown for cats primarily infected with B. henselae type II and challenged with B. henselae type I. Such results are of major importance for future feline Bartonella vaccine development.

Animals↗
PubMed2003

Clinical impact of persistent Bartonella bacteremia in humans and animals.

Bartonella spp. are emerging vector-borne pathogens that cause persistent, often asymptomatic bacteremia in their natural hosts. As our knowledge progresses, it appears that chronic infection may actually predispose the host to mild, insidious nonspecific manifestations or induce, in selected instances, severe diseases. Persistent asymptomatic bacteremia is most common in animals that serve as the main reservoir for the specific Bartonella. In humans, these organisms are B. bacilliformis and B. quintana. Other Bartonella species, for which humans are not the natural reservoir, tend to cause persistent bacteremia only in immunodeficient individuals. In some of these individuals, endothelial cell proliferation may create lesions such as bacillary angiomatosis or bacillary peliosis. In cats, bacteremia of variable level and continuity may last for years. Some strains of B. henselae may induce clinical manifestations, including fever, mild neurological signs, reproductive disorders, whereas others do not induce clinically obvious disease. Reproductive disorders have also been reported in mice experimentally infected with B. birtlesii. Finally, canids constitute the most interesting naturally occurring animal model for the human disease. Like immunocompetent people, healthy dogs only occasionally demonstrate long-term bacteremia when infected with Bartonella spp. However, some dogs develop severe clinical manifestations, such as endocarditis, and the pathologic spectrum associated with Bartonella spp. infection in domestic dogs is rapidly expanding and resembles the infrequently reported clinical entities observed in humans. In coyotes, persistent bacteremia is more common than in domestic dogs. It will be of interest to determine if coyotes develop clinical or pathological indications of infection.

Animals↗
PubMed2003

Isolation of Bartonella washoensis from a dog with mitral valve endocarditis.

We report the first documented case of Bartonella washoensis bacteremia in a dog with mitral valve endocarditis. B. washoensis was isolated in 1995 from a human patient with cardiac disease. The main reservoir species appears to be ground squirrels (Spermophilus beecheyi) in the western United States. Based on echocardiographic findings, a diagnosis of infective vegetative valvular mitral endocarditis was made in a spayed 12-year-old female Doberman pinscher. A year prior to presentation, the referring veterinarian had detected a heart murmur, which led to progressive dyspnea and a diagnosis of congestive heart failure the week before examination. One month after initial presentation, symptoms worsened. An emergency therapy for congestive heart failure was unsuccessfully implemented, and necropsy evaluation of the dog was not permitted. Indirect immunofluorescence tests showed that the dog was strongly seropositive (titer of 1:4,096) for several Bartonella antigens (B. vinsonii subsp. berkhoffii, B. clarridgeiae, and B. henselae), highly suggestive of Bartonella endocarditis. Standard aerobic and aerobic-anaerobic cultures were negative. However, a specific blood culture for Bartonella isolation grew a fastidious, gram-negative organism 7 days after being plated. Phenotypic and genotypic characterizations of the isolate, including partial sequencing of the citrate synthase (gltA), groEL, and 16S rRNA genes, indicated that this organism was identical to B. washoensis. The dog was seronegative for all tick-borne pathogens tested (Anaplasma phagocytophilum, Ehrlichia canis, and Rickettsia rickettsii), but the sample was highly positive for B. washoensis (titer of 1:8,192) and, according to indirect immunofluorescent-antibody assay, weakly positive for phase II Coxiella burnetii infection.

Animals↗
PubMed2003

Control and prevention of emerging zoonoses.

Emerging and re-emerging zoonoses are zoonotic diseases caused by either totally new or partially new agents or by microorganisms previously known but now occurring in places or in species where the disease was previously unknown. Zoonotic diseases account for the majority of all emerging infectious diseases. Several factors have led to the emergence of these infections, including human demographics, the industrialization of food production, globalization, international travel and commerce, land use, microbial adaptation, and changes and breakdown in public health measures. Several zoonotic agents are also potential agents that could be used as biological weapons. The recent use of anthrax spores in tainted mall in the US underlines our need for preparedness against bioterrorism. Prevention and control of these emerging zoonotic diseases is based on recognition, investigation, and collaboration, the development of advanced diagnosis and surveillance tools, the use of applied epidemiology and molecular biology methods, as well as education, information, communication, and technology transfer.

Animals↗
PubMed2002

Molecular epidemiology of Bartonella henselae infection in human immunodeficiency virus-infected patients and their cat contacts, using pulsed-field gel electrophoresis and genotyping.

Bartonella henselae causes severe disease in immunocompromised individuals. B. henselae was isolated from 12 human immunodeficiency virus (HIV)-infected individuals with bacillary angiomatosis and/or peliosis hepatis and from their 15 cat contacts. Specific associations between the 2 B. henselae genotypes, individual pulsed-field gel electrophoresis (PFGE) patterns, and different clinical syndromes and pathogenicity were investigated. The role of cat contacts as the source of human infection was also examined. Three of the 4 patients with B. henselae genotype I infection, but none of the 8 patients with genotype II infection, had hepatosplenic vascular proliferative lesions (P=.018). Four of 5 human-cat pairs had closely-related PFGE patterns and concordant results by 16S rDNA typing, which strongly suggests that human infection was caused by the cat contact. These results corroborate the major role of cats in the transmission of B. henselae to humans and suggest that B. henselae genotypes may induce different pathological features in HIV-infected patients.

Angiomatosis, Bacillary↗
PubMed2002

Investigation of Bartonella infection in ixodid ticks from California.

A total of 1253 ixodid ticks (254 tick pools) collected between the end of 1995 and the spring of 1997 from six California counties (El Dorado, Los Angeles, Orange, Santa Cruz, Shasta and Sonoma) were examined for the presence of Bartonella DNA by PCR of the citrate synthase gene. Of 1,119 adult Ixodes pacificus ticks tested, 26 (11.6%) of 224 pools, each containing five ticks, were positive (minimum percentage of ticks harboring detectable Bartonella DNA, 2.3%). Bartonella PCR-positive ticks were identified in five counties but none of the ticks from Los Angeles County was positive. Among 47 nymphal I. pacificus ticks collected in Sonoma County, one (10%) positive pool out of 10 pools was identified (minimum percentage of ticks harboring detectable Bartonella DNA, 2.1%). Among the 54 Dermacentor occidentalis grouped in 12 pools from Orange County, one pool (8.3%) was PCR positive for Bartonella and similarly one pool (14.3%) was positive among the 30 Dermacentor variabilis ticks grouped in seven pools. None of the three D. occidentalis from El Dorado County were positive. None of the nine tick pools positive for Ehrlichia phagocytophila were positive for Bartonella. Following our previous findings of Bartonella PCR-positive adult I. pacificus ticks in central coastal California, this is the first preliminary report of the presence of Bartonella DNA in I. pacificus nymphs and in Dermacentor sp. ticks. Distribution of Bartonella among ixodid ticks appears widespread in California.

Animals↗
PubMed2002

Characterization of the first Bartonella henselae strain isolated from a cat in Italy.

Bartonella henselae has been identified and characterized for the first time in Italy. A strain, designed Pavia-1, was isolated from the blood of a cat whose owner developed cat scratch disease (CSD). Pavia-1 and two American B. henselae strains (Houston-1, ATCC 49882, type I and strain 269608, UC Davis, type II) were compared by whole-cell fatty analysis (CFA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiles, Western immunoblotting (WB) for reactivity with polyclonal antibodies, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), type-specific 16S rRNA PCRs, and pulsed-field gel electrophoresis (PFGE). Bartonella clarridgeiae (ATCC 51734) was also included for comparison. Pavia-1 was identified as a B. henselae type I. PFGE allowed differentiation between B. clarridgeiae and B. henselae and furthermore, between all the B. henselae strains. The fingerprints of PFGE observed for Pavia-1 were distinct from those of B. henselae type II and also of Houston-1, suggesting that the two type I strains derived from two different clones. These results show the capability of B. henselae to develop genotypic variability between genetically related strains.

Adult↗
PubMed2002

Bartonella bovis Bermond et al. sp. nov. and Bartonella capreoli sp. nov., isolated from European ruminants.

Two novel species of Bartonella isolated from European ruminants are described. Bartonella capreoli sp. nov. was isolated from the blood of roe-deer (Capreolus capreolus) captured in Chizé, France. The type strain is IBS 193T (= CIP 106691T = CCUG 43827T). It is distinct from another European ruminant isolate that originated from a cow from a French herd of 430 dairy cattle. The latter isolate belongs to a novel species named Bartonella bovis Bermond et al. sp. nov. The type strain is strain 91-4T (= CIP 106692T = CCUG 43828T). The two bacteria appeared as small, fastidious, aerobic, oxidase-negative, gram-negative rods. Their biochemical properties were similar to those of members of the genus Bartonella. The sequences of the 16S rRNA and citrate synthase genes obtained from the two type strains were highly related to sequences of the different Bartonella species. Hybridization values when testing type strains of recognized Bartonella species, obtained with the nuclease/trichloroacetic acid method, support the creation of two novel species.

Animals↗
PubMed2002

Experimental infection of domestic cats with Bartonella koehlerae and comparison of protein and DNA profiles with those of other Bartonella species infecting felines.

Bartonella koehlerae, a recently described feline Bartonella species, was isolated from two naturally infected cats in northern California. We experimentally infected domestic cats with B. koehlerae to establish the microbiological and immunological characteristics of this infection in cats and to compare it to infections with those caused by B. henselae and B. clarridgeiae. Four cats were inoculated intradermally with B. koehlerae (8.6 x 10(7) to 3.84 x 10(8) CFU/ml). None of the cats presented any obvious clinical signs, but all cats developed bacteremia, which peaked at 3.36 x 10(4) to 1.44 x 10(6) CFU/ml of blood between day 14 and day 36 postinoculation. B. koehlerae-inoculated cats had a bacteremia duration (mean, 74 days) shorter than did cats inoculated with B. clarridgeiae (mean, 324 days) (P = 0.03). None of the four cats inoculated with B. koehlerae had bacteremia relapse. As shown by enzyme-linked immunosorbent assay (ELISA) using B. koehlerae outer membrane protein (OMP) antigens, the four cats developed a species-specific antibody response, and ELISA testing using other feline Bartonella OMP antigens showed statistically lower optical density values. All four cats developed similar antibody reactivity patterns to B. koehlerae OMP antigens as seen by Western blotting, each with at least 20 seroreactive protein bands. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, protein profile differences were observed for both whole-cell lysate and OMPs from B. koehlerae, compared with B. henselae and B. clarridgeiae. B. koehlerae was more closely related to B. henselae than to B. clarridgeiae by protein profile, and this relatedness was also confirmed by analysis of the genomic DNA profiles by pulsed-field gel electrophoresis.

Animals↗
PubMed2002

Time-space clustering of human brucellosis, California, 1973-1992.

Infection with Brucella spp. continues to pose a human health risk in California despite great strides in eradicating the disease from domestic animals. Clustering of human cases in time and space has important public health implications for understanding risk factors and sources of infection. Temporal-spatial clustering of human brucellosis in California for the 20-year period 1973-1992 was evaluated by the Ederer-Myers-Mantel, Moran's I, and population-adjusted Moran's I procedures. Cases were clustered in concentrated agricultural regions in the first 5-year interval (1973-1977). Time-space clustering of human brucellosis cases in California late in the 20-year study period may reflect the distribution of Hispanic populations. Public health programs in California should focus on educating Hispanic populations about the risk of consuming dairy products, such as soft cheeses, made from unpasteurized milk.

Animals↗
PubMedDate not supplied

Prevalence of Bartonella infection in domestic cats in Denmark.

Whole blood and serum from 93 cats (44 pets and 49 shelter/stray cats) from Denmark were tested for the presence of feline Bartonella species by culture and for the presence of Bartonella antibodies by serology. Bartonella henselae was isolated from 21 (22.6%) cats. Bacteremia prevalence was not statistically different between shelter/stray cats (13/49, 26.5%) and pet cats (8/44, 18.2%), but varied widely by geographical origin of the cats, even after stratification for cat origin or age (p < 0.001). All isolates but one were B. henselae type II. The only cat bacteremic with B. henselae type I was not co-infected with B. henselae type II. None of the cats was harboring either B. clarridgeiae or B. koehlerae. Almost half (42/92, 45.6%) of the cats were seropositive for B. henselae and antibody prevalence was similar in shelter/stray cats (23/49, 46.9%) and pet cats (19/43, 44.2%). This is the first report of isolation of B. henselae from domestic cats in Denmark. This study also indicates that domestic cats, including pet cats, constitute a large Bartonella reservoir in Denmark.

Animals↗
PubMedDate not supplied

Experimental infection of specific pathogen free (SPF) cats with two different strains of bartonella henselae type I: a comparative study.

Domestic cats are the reservoir of Bartonella henselae, the main causative agent of cat scratch disease. We compared B. henselae type I infection characteristics in 6 SPF cats infected with a feline strain (4.8 x 10(7) colony-forming units (CFU)/mL) and in 6 SPF cats infected with the reference Houston I strain (6.6 x 10(6) CFU/mL to 9.6 x 10(7) /mL). All the cats inoculated with the feline strain, but none of the cats inoculated with B. henselae Houston I, developed a fever within 2-12 days (mean: 5.8 days) post inoculation (PI), which lasted for 1-2 weeks. However, all 12 cats became bacteremic. The duration of bacteremia was significantly longer in the cats inoculated with the feline strain (mean: 237 days) than in the cats inoculated with Houston I strain (mean: 60 days) (p < 0.01). Five (83%) cats inoculated with the feline strain and none of the six cats inoculated with B. henselae Houston I had relapsing bacteremia (p = 0.02). IgG antibodies were detected by IFA within 1-2 weeks for both strains, but peaked later (week 10 versus week 3 PI) for the feline strain. By ELISA, using antigens of each B. henselae strain, all 12 cats developed Bartonella specific IgM and IgG antibodies, but the cats infected with B. henselae Houston I antigen yielded significantly lower optical density values (p < 0.05). By SDS-PAGE, PFGE and Western blotting, protein profile differences (84 to 89% homology) were observed between the two strains. If a feline vaccine is to be developed in order to prevent human infection, the choice of the vaccine strain will be critical, since major differences were identified even between strains belonging to the same sero/genotype.

Animals↗
PubMedDate not supplied

Seroprevalence of Bartonella infection in American free-ranging and captive pumas (Felis concolor) and bobcats (Lynx rufus).

Bartonella henselae is the main agent of cat scratch disease in humans and domestic cats are the main reservoir of this bacterium. We conducted a serosurvey to investigate the role of American wild felids as a potential reservoir of Bartonella species. A total of 479 samples (439 serum samples and 40 Nobuto strips) collected between 1984 and 1999 from pumas (Felis concolor) and 91 samples (58 serum samples and 33 Nobuto strips) collected from bobcats (Lynx rufus) in North America, Central America and South America were screened for B. henselae antibodies. The overall prevalence of B. henselae antibodies was respectively 19.4% in pumas and 23.1% in bobcats, with regional variations. In the USA, pumas from the southwestern states were more likely to be seropositive for B. henselae (prevalence ratio (PR) = 2.82, 95% confidence interval (CI) = 1.55, 5.11) than pumas from the Northwest and Mountain states. Similarly, adults were more likely to be B. henselae seropositive than juveniles and kittens (PR = 1.77, 95% CI = 1.07, 2.93). Adult pumas were more likely to have higher B. henselae antibody titers than juveniles and kittens (p = 0.026). B. henselae antibody prevalence was 22.4% (19/85) in bobcats from the USA and 33.3% (2/6) in the Mexican bobcats. In the USA, antibody prevalence varied depending on the geographical origin of the bobcats. In California, the highest prevalence was in bobcats from the coastal range (37.5%). These results suggest a potential role of wild felids in the epidemiological cycle of Bartonella henselae or closely related Bartonella species.

Animals↗