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T Bodmer

Publications and source records attributed to T Bodmer.

36 records · Page 2Linked to original sources
PubMed1995

Evaluation of the relatedness of strains of Mycobacterium avium using pulsed-field gel electrophoresis.

The application of molecular techniques to investigate strain relatedness may help define the local epidemiology of Mycobacterium avium infection, and, by identifying false isolates (i.e. neither pathogens nor colonizers) resulting from contamination, may serve as a tool for quality control in the laboratory. For this purpose, isolates from all patients (n = 129) with Mycobacterium avium infections identified over a two-year period were investigated by pulsed-field gel electrophoresis (PFGE). Of 38 PFGE patterns identified, 34 corresponded to unique strains or to isolates present in no more than two or three individuals. One prevalent strain was identified among HIV-infected patients and three patterns were related to culture contamination events. PFGE (i) established the diversity of Mycobacterium avium strains in a community; (ii) identified the existence of a unique strain that may account for one-fifth of Mycobacterium avium isolated from HIV-infected patients locally; (iii) documented the extent and resolution of a suspected pseudo-outbreak; and (iv) uncovered an additional-unsuspected contamination event.

AIDS-Related Opportunistic Infections↗
PubMed1995

A novel insertion element from Mycobacterium avium, IS1245, is a specific target for analysis of strain relatedness.

The insertion sequence IS1245 is a novel mycobacterial repetitive element identified in Mycobacterium avium. It encodes a transposase which exhibits a 64% amino acid similarity with IS1081, an insertion element present in the M. tuberculosis complex. The host range of IS1245 appears limited to M. avium as this element was not identified in M. intracellulare or in any other of 18 mycobacteria species tested. When IS1245 was used for restriction fragment length polymorphism (RFLP) analysis, human isolates characteristically presented a high number of copies (median, 16; range, 3 to 27) and a diversity of RFLP patterns comparable to that found by pulsed-field gel electrophoresis. Isolates from nonhuman sources differed both in number of copies and in RFLP pattern diversity: while swine isolates shared the characteristics of human strains, those from several avian sources exhibited a very low copy number of IS1245 and appeared clonal on the basis of RFLP.

Animals↗
PubMed1995

Comparison of random amplified polymorphic DNA with restriction fragment length polymorphism as epidemiological typing methods for Mycobacterium tuberculosis.

Aim-To compare restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) methods for the epidemiological typing of Mycobacterium tuberculosis.Methods-Thirty one M tuberculosis cultures originating from patients in the Canton of Berne in Switzerland, which had previously been typed by RFLP, were subjected to RAPD analysis. Cultures were coded so that the investigators were blind to the RFLP results until RAPD analysis was complete.Results-The 31 cultures of M tuberculosis were divided into nine groups by RFLP and eight groups by RAPD. Generally there was good correlation between the groups identified by the two techniques, with the exception of strains that had only one copy of IS6110. Both methods subdivided isolates that were placed in a single group by the other method.Conclusions-RAPD analysis is quick, simple, and useful for the comparison of small numbers of isolates. RFLP is more reproducible and therefore better suited for the accumulation of RFLP fingerprints for long term local surveillance and large epidemiological studies.

Journal Article↗
PubMed1994

[Disseminated nontuberculous mycobacterial infections in AIDS patients].

Disseminated nontuberculous mycobacteriosis is a frequent and late complication of HIV infection. All the 13 patients described here had CD4-lymphocyte counts < 20/mm3. The causative agent was mainly M. avium complex. But we also found, for the first time, a double infection with M. avium complex and M. "genavense" and one patient with growth of M. shimoidei in the blood culture. Clinical signs are nonspecific (fever, reduced performance, anemia). Positive cultures of blood or tissue biopsies are diagnostic. The therapeutic approach is the combination of new macrolides with other antimycobacterial agents. Prognosis is poor, mainly due to advanced immunodeficiency, but two of our patients survived more than one year after diagnosis. Prophylactic treatment should be considered in patients with CD4-counts less than 50/mm3.

AIDS-Related Opportunistic Infections↗
PubMed1994

Permeation of human chorioamniotic membranes by Escherichia coli in vitro.

OBJECTIVE: Our goal was to study the permeation of Escherichia coli through human chorioamniotic membranes in vitro. STUDY DESIGN: Medium was placed in two compartments separated by chorioamniotic membranes obtained from six cesarean sections at term. The compartment faced by the chorion was inoculated with E. coli. Both compartments were sampled over 12 hours for observation of bacterial growth. Controls were performed without membranes. RESULTS: In the compartment that was inoculated, concentration of E. coli increased from 10(6) to 10(10) colony-forming units per milliliter. In the compartment faced by amnion, bacterial growth was observed after 6 hours and reached 10(3) colony-forming units per milliliter. Permeation of E. coli was confirmed histopathologically. The change of glucose and lactate was linear. In the controls the concentration of E. coli increased to 10(7) (p < 0.001). CONCLUSIONS: E. coli organisms permeate viable chorioamniotic membranes. The membranes constitute a weak barrier against ascending infection and do not inhibit bacterial growth.

Amnion↗
PubMed1994

Screening of respiratory tract specimens for the presence of Mycobacterium tuberculosis by using the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test.

A prospective 2-month trial involving 617 respiratory tract specimens was conducted to compare sensitivity, specificity, and predictive values of the newly developed Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test kit (AMTDT; Gen-Probe, Inc., San Diego, Calif.) for the rapid detection of Mycobacterium tuberculosis and of fluorescent acid-fast staining versus combined BACTEC 12B and solid-medium cultures as the "gold standard." A total of 590 specimens were culture and AMTDT negative. Twenty-one (3.4%) cultures yielded M. tuberculosis. Of these, 15 (71.4%) were detected by AMTDT, whereas 6 (28.6%) were missed. M. tuberculosis did not grow in six (28.6%) of AMTDT-positive specimens derived from three patients under treatment for tuberculosis. AMTDT exhibited a sensitivity, a specificity, a negative predictive value, and a positive predictive value of 71.4, 99, 99, and 71.4%, respectively. In comparison, the same values for fluorescent microscopy were 66.7, 98.3, 98.8, and 58.3%, respectively. AMTDT was easy to perform and highly specific. However, a screening test would require an improved sensitivity and, when feasible, the implementation of an internal amplification control.

Bacteriological Techniques↗
PubMed1993

Molecular approach to identifying route of transmission of tuberculosis in the community.

There is growing concern that tuberculosis is spread in Europe in the way that it is in the USA. We have used DNA "fingerprinting" in a systematic evaluation of tuberculosis cases notified in our community to uncover foci of transmission. An IS6110 probe was used to test all isolates from culture-confirmed tuberculosis cases (163 patients) notified in 1991-92 in the Canton of Berne. In total, 45 patients (27.6%), potentially linked on the basis of restriction fragment length polymorphism, were investigated epidemiologically. The largest group (n = 22) included members of a defined social group (drug addicts, homeless persons, alcoholics), from whom tuberculosis spread to the general population. A key patient developed multidrug-resistant tuberculosis during the surveillance period. This population study showed that (i) extensive transmission of Mycobacterium tuberculosis is now taking place in Europe in the same social setting as in the USA; (ii) there is definite "spillover" to the general population; (iii) the dimensions of the problem cannot be recognised easily by routine public health service activities because of the complexity of the transmission network; and (iv) multidrug-resistant tuberculosis develops in this setting.

Adult↗
PubMed1993

Detection of rifampicin-resistance mutations in Mycobacterium tuberculosis.

Control of tuberculosis is threatened by widespread emergence of drug resistance in Mycobacterium tuberculosis. Understanding the molecular basis of resistance might lead to development of novel rapid methods for diagnosing drug resistance. We set out to determine the molecular basis of resistance to rifampicin, a major component of multidrug regimens used for treating tuberculosis. Resistance to rifampicin involves alterations of RNA polymerase. The gene that encodes the RNA polymerase subunit beta (rpoB) was cloned. Sequence information from this gene was used to design primers for direct amplification and sequencing of a 411 bp rpoB fragment from 122 isolates of M tuberculosis. Mutations involving 8 conserved aminoacids were identified in 64 of 66 rifampicin-resistant isolates of diverse geographical origin, but in none of 56 sensitive isolates. All mutations were clustered within a region of 23 aminoacids. Thus, substitution of a limited number of highly conserved aminoacids encoded by the rpoB gene appears to be the molecular mechanism responsible for "single step" high-level resistance to rifampicin in M tuberculosis. This information was used to develop a strategy (polymerase chain reaction-single-strand conformation polymorphism) that allowed efficient detection of all known rifampicin-resistant mutants. These findings provide the basis for rapid detection of rifampicin resistance, a marker of multidrug-resistant tuberculosis.

Base Sequence↗
PubMed1993

Invasive infection with Mycobacterium genavense in three children with the acquired immunodeficiency syndrome.

Three children with human immunodeficiency virus infection and invasive infection with Mycobacterium genavense are reported. Fever spikes, abdominal cramps and distension, diarrhea or ileus, and anemia were the predominant symptoms in the severely immunodeficient patients (CD4 lymphocytes < 0.04 x 10(9)/l). Numerous acid-fast bacilli were readily detectable by microscopy in stool samples and in lymph node biopsies, but cultures for mycobacteria remained negative. Mycobacterium genavense should be sought when invasive non-tuberculous mycobacteriosis is suspected and mycobacterial cultures from blood or other sites show limited growth. Multiple-drug regimens including amikacin, ethambutol, rifampin, and clarithromycin may be of benefit in controlling the infection, as observed in two patients.

AIDS-Related Opportunistic Infections↗
PubMed1993

Direct, automated detection of rifampin-resistant Mycobacterium tuberculosis by polymerase chain reaction and single-strand conformation polymorphism analysis.

A rapid screening test was recently established for the detection of mutations in the rpoB gene of Mycobacterium tuberculosis, a region identified as the locus for rifampin resistance (Rifr). The detection method involved the amplification by polymerase chain reaction (PCR) of the Rifr region and the identification of mutations by single-strand DNA conformation polymorphism analysis (SSCP) of the amplification products. Experience using two different PCR-SSCP formats for the evaluation of BACTEC cultures and sputum is presented here; the previously described manual procedure for the detection for the detection of radiolabelled amplification products and an automated SSCP by which fluorescein-labelled products were detected on a Pharmacia DNA sequencer apparatus. All 17 different Rifr mutations known to date were consistently detected. PCR-SSCP could be used for the evaluation of minimally grown cultures (BACTEC 12B medium with a growth index of < or = 100) and for direct screening of microscopically positive sputa with greater than 10 organisms per field (magnification, x250). Implementation of this technique could result in rapid detection of rifampin resistance in M. tuberculosis, a marker of multidrug-resistant tuberculosis.

Base Sequence↗
PubMed1993

Rapid identification of mycobacteria to the species level by polymerase chain reaction and restriction enzyme analysis.

A method for the rapid identification of mycobacteria to the species level was developed on the basis of evaluation by the polymerase chain reaction (PCR) of the gene encoding for the 65-kDa protein. The method involves restriction enzyme analysis of PCR products obtained with primers common to all mycobacteria. Using two restriction enzymes, BstEII and HaeIII, medically relevant and other frequent laboratory isolates were differentiated to the species or subspecies level by PCR-restriction enzyme pattern analysis. PCR-restriction enzyme pattern analysis was performed on isolates (n = 330) from solid and fluid culture media, including BACTEC, or from frozen and lyophilized stocks. The procedure does not involve hybridization steps or the use of radioactivity and can be completed within 1 working day.

Bacterial Proteins↗
PubMed1992

[Systemic Nocardia infection in an AIDS patient].

We report the case of a patient with Aids, Kaposi's sarcoma and a systemic nocardial infection. After surgical drainage and adequate antibiotic treatment the infection was cured. Under secondary antimicrobial prophylaxis no relapse has occurred to date. Generalized N. asteroides infections have been rarely described in patients with Aids and the possible reasons for this are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Successful treatment of disseminated nocardiosis complicated by cerebral abscess with ceftriaxone and amikacin: case report.

We report the case of an 85-year-old female patient who suffered from disseminated Nocardia asteroides infection complicated by a cerebral abscess. Treatment with amikacin for 2 weeks and ceftriaxone for 6 weeks led to complete recovery, and there was no recurrence of disease over a follow-up period of 12 months after therapy. The use of ceftriaxone in combination with amikacin might significantly shorten the duration of treatment for patients with disseminated nocardiosis. This combination of antibiotics merits further investigation with use of a larger sample of patients.

Aged↗
PubMed1991

[Rhodococcus erythropolis infection in HIV-associated immunodeficiency].

We report the first case in the literature of human infection with Rhodococcus erythropolis in an HIV-positive patient. A 24-year-old bisexual flight attendant had severe HIV-associated immunodeficiency with a CD4 cell count of 0.02 G/l. He complained of multiple subcutaneous nodules at different sites on the extremities. Biopsy of one node at his left knee revealed granulomatous inflammation filled with acid-fast rods. These bacteria were identified as Rhodococcus erythropolis. The disseminated infection was restricted to the skin and showed a slow response to long-term therapy with amoxicillin/clavulanic acid. No relapse has been observed more than 6 months after discontinuation of antibiotic therapy. The etiology of a concomitant polyarthritis remains unknown; a relationship with the rhodococcus infection is possible as the arthritis responded well to the antibiotic therapy and did not reactivate after discontinuation of antibiotics. Due to the difficult isolation technic, this pathogen may be overlooked in routine diagnostic procedures. The implications in clinical practice are discussed.

Actinomycetales Infections↗
PubMedDate not supplied

Molecular epidemiology of tuberculosis among HIV-infected persons in Switzerland: a countrywide 9-year cohort study. Swiss HIV Cohort Study.

We investigated tuberculosis transmission during a nine-year period (1988-1996) in a countrywide community-based cohort of HIV-infected persons in Switzerland (the Swiss HIV Cohort Study [SHCS]). We estimated the proportion of tuberculosis cases due to reinfection and relapse, and assessed factors which may increase the risk of tuberculosis transmission. HIV-infected persons were followed prospectively and molecular fingerprinting with insertion sequence (IS) 6110, 36-bp direct repeat, and IS6110-PCR was used to determine M. tuberculosis case clustering. Out of 7999 SHCS participants, 267 persons developed tuberculosis. 158 M. tuberculosis isolates from 138 patients were available for study. Molecular analysis identified 33 (24%) episodes of tuberculosis associated with 12 clusters including 2 to 8 patients. Two patients experienced reinfection, and nine had a relapse. Detailed contact investigation identified definite or possible epidemiological links between 21 of 33 cluster patients (64%). Multivariate logistic regression analysis did not identify any risk marker significantly associated with clustering. During a nine-year period, one fourth of tuberculosis cases were grouped in clusters within a selection of 138 HIV-infected patients. This may represent the lowest estimation of recently acquired tuberculosis infection. There were no large institutional or community outbreaks among HIV-infected participants of the Swiss HIV Cohort Study.

AIDS-Related Opportunistic Infections↗