Biomedical subjects
Publications and source records attributed to V Vincent.
The prevalence of human tuberculosis (TB) due to Mycobacterium bovis was determined in Madagascar in 1994-1995. A prevalence of M. bovis of 1.25% was observed among sputum smear-positive patients and 1.3% among extra-pulmonary TB patients. This study was conducted in urban areas and will be extended to rural zones, where the majority of the population lives.
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OBJECTIVE: To evaluate the role of Mycobacterium bovis in the epidemiology of human tuberculosis in France. DESIGN: A national survey in France in 1995 using a questionnaire mailed to all French microbiological laboratories performing mycobacteria cultures. RESULTS: M. bovis was isolated in 38 out of 7075 cases of bacteriologically confirmed tuberculosis (0.5%) notified to the National Reference Centre (CNR) in 1995, resulting in an incidence of 0.07 per 100,000 population. Incidence rates increased with age, and were the highest among patients of 75 years or more (range 0.02-0.33/100,000). Two cases of tuberculosis due to M. bovis were reported in foreign-born children who had come to France for treatment of their disease. No cases were reported among French-born children. The site of tuberculosis was pulmonary in 17 cases, extra-pulmonary in 14, both pulmonary and extra-pulmonary in one, and unknown in six. Extra-pulmonary sites were more frequent in older patients, and pulmonary sites more frequent in younger patients. Two patients were coinfected with the human immunodeficiency virus. Occupational exposure was identified in 13 cases and ingestion of non pasteurised milk in three. In addition, 11 patients had a possible risk of exposure related to their country of birth, family contact or occupation. CONCLUSION: In France, the 0.5% proportion of human tuberculosis due to M. bovis is similar to that of other developed countries. The higher incidence of the disease among older people is likely to reflect the efficacy of the control measures for tuberculosis in cattle.
SETTING: A national survey of resistance to the antituberculosis drugs used in Côte d'Ivoire was conducted in 1995-1996. OBJECTIVE: To determine the rate of primary resistance to antituberculosis drugs. METHODS: Consecutive new tuberculous patients with positive smear were recruited from tuberculosis centres and rural health centres. Drug susceptibility testing was performed according to the proportion method. Positive cultures were tested against streptomycin, isoniazid, rifampicin, and ethambutol. All resistant strains and 10% of all randomly sampled cultures were sent to an external laboratory for quality control. Human immunodeficiency virus (HIV) tests were performed for consenting patients at the tuberculosis centres. RESULTS: Among the 430 samples, 320 were available for analysis. Primary resistance to antituberculosis drugs was observed for 13.4% of the patients (43/320); multidrug resistance (to at least isoniazid and rifampicin) was observed for 5.3% of the patients; 14.2% of HIV-negative and 16.2% of HIV-positive patients were resistant to at least one antituberculosis drug (P = 0.70). CONCLUSION: This study is representative of antituberculosis drug resistance in Côte d'Ivoire. The rate of primary resistance is high and emphasises the need for a sentinel survey of tuberculous resistance. The National Tuberculosis Control Programme needs to make improvements in its management of tuberculosis cases.
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Mycobacterium celatum is a recently described slow-growing species. It was identified on the basis of genomic sequencing that differentiates three types. The present report describes two cases of Mycobacterium celatum type 1 infection in patients with AIDS. Both patients had CD4+ lymphocyte counts of < 10/mm3, were receiving rifabutin prophylaxis, and had attended the same treatment units. The minimum inhibitory concentration of rifabutin for both strains was 8 mg/l, which may account for the failure of prophylaxis. As all type 1 strains have the same pulsed-field gel electrophoresis pattern, nosocomial transmission or acquisition from a common source could not be ruled out.
We introduced open adjustable silicone gastric banding (ASGB) for treatment of morbid obesity in our institution in 1991. It was done in a prospective study comparing ASGB with vertical banded gastroplasty (VBG) with regard to weight loss. After 200 cases of open ASGB and 210 VBG procedures and the encouraging weight loss results, we started laparoscopic placement of the adjustable silicone band. The initial work was done in an animal laboratory program where a new surgical protocol has been established. Details of the laparoscopic dissection around the stomach in a deep operative field and fatty atmosphere have been developed, and a laparoscopically implantable version of the adjustable silicone band (LAGB) has been devised. The first human laparoscopic ASGB procedure was performed in our institution on September 1, 1993. Altogether 350 patients had undergone adjustable silicone gastric banding (LASGB) procedures by May 1997 (277 women, 73 men). All the patients were morbidly obese, with an average preoperative weight of 118 kg (92-200 kg). The mean BMI was 43 kg/m2 (36-65 kg/m2). The conversion rate to laparotomy has been low (1.4%). Early complications have been rare, and pouch dilatation and stomach slippage have been the only significant late complications. The rate of these complications has been considerably improved by reducing the pouch volume and using more gastrogastric sutures. Evaluation of postoperative weight loss of LASGB patients compared with our VBG and ASGB (open) patients showed a similar curve.
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Mycobacterium avium has become a major human pathogen, primarily due to the emergence of the AIDS epidemic. Restriction fragment length polymorphism (RFLP) typing, using insertion sequence IS1245 as a probe, provides a powerful tool in the molecular epidemiology of M. avium-related infections and will facilitate well-founded studies into the sources of M. avium infections in animal and environmental reservoirs. The standardization of this technique allows computerization of IS1245 RFLP patterns for comparison on a local level and the establishment of M. avium DNA fingerprint databases for interlaboratory comparison. Moreover, by combining international DNA typing results of M. avium complex isolates from a broad spectrum of sources, long-lasting questions on the epidemiology of this major agent of mycobacterial infections will be answered.
Forty-three percent of the tuberculosis cases reported in France are from the Ile de France region. The incidence of tuberculosis in this region is 33 cases per 100,000 inhabitants, twice the national average. A restriction fragment length polymorphism (RFLP) analysis was performed with clinical isolates of Mycobacterium tuberculosis isolated during 1995 in 10 hospitals in Paris and surrounding areas to detect tuberculosis transmission and define the factors associated with clustering in this population. The molecular markers used were the insertion sequence IS6110 and the direct repeat (DR) sequence. Social, demographic, and clinical data were collected from the patients' medical files. Ten patients with isolates with a single copy of IS6110 were excluded from further analysis. Twenty-four patients with false-positive cultures due to laboratory contamination (based on RFLP analysis with IS6110 and examination of patient data) were also excluded. The study was then conducted with 272 strains isolated from 272 patients. Further fingerprinting was performed by using the DR element with strains with patterns by RFLP analysis with IS6110 that differed by one band only and strains with identical patterns by RFLP analysis with IS6110 and with low numbers of copies of IS6110. The combined use of both markers identified unique patterns for 177 strains and clustered 95 (35.7%) strains in 26 groups, each containing isolates from 2 to 12 patients. The clustering was strongly associated with homelessness and the male sex. It was not associated with age, birth in a foreign country, human immunodeficiency virus positivity, or residence in hostels or prison. Isolates from homeless people were often included in large clusters, and homeless people could be the source of tuberculosis transmission for more than 50% of the clustered patients. These results suggest that homeless people play a key role in the spread of M. tuberculosis in the community and that poor socioeconomic conditions are the main risk factors associated with active tuberculosis transmission.
A new insertion sequence, IS1512, from Mycobacterium gordonae was cloned and sequenced. This element is present in up to 10 copies which provides a high diversity for restriction fragment length polymorphism analysis. We have also identified truncated IS1512-like elements, including a truncated IS1512 and another truncated insertion sequence which displays homology with IS1512 and was designated IS1511. Sequences homologous to the previously described transposon Tn554 are inserted into these truncated insertion sequences. Insertion loci of IS1511/IS1512 are shown to be highly related to those described for IS256-like elements in other species. Alignment of the putative transposases from Rhodococcus and Mycobacterium suggests these insertion sequences may form a distinct closely homologous subclass within the IS256 family. Analysis comparing phylogenetic divergence of these elements with that of 16S rRNA and superoxide dismutase genes suggests horizontal transfer of a IS1511/IS1512 precursor into M. gordonae, and the occurrence of horizontal transfer between Mycobacteriaceae and Rhodococcaceae.
Cloning of rat prolactin receptor (PRLR) cDNAs revealed the existence of two isoforms, termed short and long according to the length of their cytoplasmic domain. Internalization studies show, first, that PRLR internalization is hormone-dependent and, second, that ligand-receptor complexes of the short PRLR are internalized to a larger extent compared to the long form. In order to identify regions within the cytoplasmic domain of the short PRLR required for efficient internalization, serial truncations of the cytoplasmic tail were performed by inserting a stop codon in place of those encoding residues 282, 273, 262, 253, 244, or 237 (wild type short PRLR contains 291 amino acids). Our data show that two motifs, lying within residues 253-261 and 273-281, are involved in internalization. Both regions contain a consensus feature identified within other receptors as internalization signals, namely a di-leucine peptide (amino acids 259-260) and a tetrapeptide predicted to adopt a beta-turn structure (amino acids 276-279). We propose these two motifs are involved in PRLR endocytosis. Finally, we show that alpha-adaptin, a component of adaptor protein AP-2, coprecipitates with short PRLR complexes upon PRL stimulation, which strongly suggests that PRLR internalization is mediated by the clathrin-coated pits endocytotic pathway.
We conducted a randomized, open-label trial in 42 French hospitals to compare the clinical and bacteriologic efficacy of combination therapy with clarithromycin/clofazimine (Clm/Clof) with that of combination therapy with clarithromycin/rifabutin/ethambutol (Clm/Rib/Eth) as treatment for Mycobacterium avium bacteremia. One hundred forty-four human immunodeficiency virus-seropositive patients older than 18 years of age who had CD4 lymphocyte counts of <100/mm3 and a blood culture positive for M. avium were enrolled in the study. The main measures of outcome were blood cultures, abatement of clinical symptoms (fever), and survival. Treatment success (defined as patient living, either no fever or a reduction of > or = 1 degrees C in initial body temperature, and a blood culture negative for M. avium) was similar in both treatment groups at months 2 and 6. However, following initial resolution of infection, relapse of M. avium bacteremia occurred in more patients in the Clm/Clof group than in the Clm/Rib/Eth group (22 vs. six, respectively; P < .001); these relapses were accompanied by emergence of strains resistant to clarithromycin in 21 and two patients, respectively. In conclusion, combination therapy with Clm/Rib/Eth prevented relapse of mycobacterial disease and, compared with combination therapy with Clm/Clof, was associated with a significant decrease in the emergence of resistant M. avium strains in HIV-infected patients treated for at least 28 weeks.
Mycobacterium smegmatis is a common environmental mycobacterium that was first identified in 1884, yet is a rare pathogen in humans. The few M. smegmatis infections reported to date have been localized and have occurred in association with a primary lesion in otherwise immunocompetent individuals. To our knowledge, no case of disseminated M. smegmatis infection has ever been reported, even in patients with severe immune deficiencies. We report a case of disseminated mycobacterial infection that was diagnosed in a 3-year-old girl. The pathogen was not identified as M. smegmatis until the patient was 6 years old. Her condition gradually worsened, and she died when she was 8 years old despite appropriate antimycobacterial therapy. No other opportunistic infections were documented. Immunological investigations revealed an inherited interferon gamma receptor 1 deficiency. This report identifies M. smegmatis as a new opportunistic agent that may be responsible for disseminated disease in immunocompromised individuals.
Genomic analyses of 18 Mycobacterium celatum strains obtained from different patients in three countries (United States, United Kingdom, and France) were performed; the methods used in this study were restriction fragment length polymorphism (RFLP) analysis, pulsed-field gel electrophoresis (PFGE) analysis, and PCR restriction analysis (PRA) of the hsp-65 gene. A new insertion sequence, IS1407 (GenBank accession no. X97307), belonging to the IS256 family, was identified in M. celatum type 1 strains and was characterized by sequencing. When a probe for Mycobacterium xenopi IS1395-like sequences was used, the RFLP analysis of M. celatum type 1 strains revealed that they contained three or four copies of IS1407 in identical genomic positions, while this element was absent in all M. celatum type 2 strains. PFGE performed with three different endonucleases revealed a unique large restriction fragment (LRF) pattern for M. celatum type 1 strains, whereas the LRF patterns obtained for M. celatum type 2 strains were polymorphic. Moreover, PFGE of nondigested genomic DNA revealed extrachromosomal elements in M. celatum type 2. The type strain of M. celatum type 3 could not be differentiated from M. celatum type 1 strains on the basis of the results of the RFLP analysis, the PFGE analysis, and the PRA of IS1407. In this study we confirmed that M. celatum types 1 and 2 represent distinct genomic clusters and that the molecular markers in M. celatum type 2 exhibit greater polymorphism than the molecular markers in M. celatum type 1.