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R Auckenthaler

Publications and source records attributed to R Auckenthaler.

At least 37 records · Page 2Linked to original sources
PubMed1999

Assessment of use of the COBAS AMPLICOR system with BACTEC 12B cultures for rapid detection of frequently identified mycobacteria.

The use of the COBAS AMPLICOR System (Roche Molecular Diagnostics, Basel, Switzerland), the only automated system for PCR testing, was evaluated for a rapid identification of mycobacteria with positive BACTEC 12B cultures. Two hundred ninety-six specimens with a growth index of >/=30 were analyzed for the presence of Mycobacterium tuberculosis complex, Mycobacterium avium, and Mycobacterium intracellulare. Compared to traditional methods and provided that samples with PCR inhibition are retested at a 1:10 dilution, the sensitivity and specificity of the COBAS AMPLICOR System with BACTEC 12B cultures were 100 and 98%, respectively. The COBAS AMPLICOR method is rapid and reliable for identifying the most common mycobacteria in cultures.

Automation↗
PubMed1998

Rapid diagnosis of pulmonary tuberculosis with the LCx Mycobacterium tuberculosis assay and comparison with conventional diagnostic techniques.

The LCx MTB amplification assay is a nucleic acid amplification test intended for the direct detection of Mycobacterium tuberculosis complex in respiratory specimens. We evaluated its performance on 2,001 consecutive respiratory specimens; 78 were culture positive for M. tuberculosis. Sensitivity, specificity, and positive and negative predictive values of this assay for all specimens compared to culture results were 88.5, 97.7, 60.5, and 99.5%, respectively. When referred to resolved clinical diagnosis of active tuberculosis, these values improved to 90.2, 98.4, 72.8, and 99.5%, respectively.

Bronchoalveolar Lavage Fluid↗
PubMed1998

Characterization of glycopeptide-resistant enterococci from a Swiss hospital.

Between August 1994 and September 1996, 28 glycopeptide-resistant enterococci (GRE) were isolated from 8 infected patients and 11 intestinal carriers hospitalized at the University Hospital of Geneva. Identification to the species was made by both phenotypic (API 20 STREP and Rapid ID 32 STREP systems, and Vitek Gram Positive Identification Card) and genotypic methods using a multiplex PCR assay developed also for the determination of the genotype of glycopeptide resistance (vanA, vanB, vanC1, and vanC2-C3 genes). Fifteen isolates were identified as Enterococcus faecium, 8 as E. gallinarum, 4 as E. faecalis, and 1 as E. hirae. All of the phenotypic identification methods failed to differentiate some isolates of E. gallinarum from E. faecium, or vice versa. Both vanA (n = 18) and vanB (n = 4) glycopeptide resistance genotypes were found. For the first time, the vanB determinant was found in two isolates of E. gallinarum. Two patients were colonized by two different species containing the vanA gene and one by two different species containing the vanB gene. All vanA isolates were highly resistant to both vancomycin and teicoplanin except for three isolates which were susceptible to teicoplanin. Molecular typing by pulsed-field gel electrophoresis showed identical or similar patterns among E. faecium isolates with the vanA gene in five patients for whom the epidemiological link could not be always elucidated. This study emphasizes the necessity of utilizing both phenotypic and genotypic methods to characterize GRE.

Anti-Bacterial Agents↗
PubMed1997

[Inter- and intrahospital transmission of methicillin-resistant Staphylococcus aureus].

Occurrence and spread of methicillin-resistant Staphylococcus aureus (MRSA) has become a major problem worldwide. The majority of hospitals in Switzerland have not so far been affected by this epidemic. We report two out-breaks of MRSA transmission in the surgical intensive care unit at the University Hospital of Geneva and show the possible inter- and intrahospital dissemination of MRSA. Evidence for cross-infection is confirmed by epidemiological investigation and molecular typing. Infection control measures and general precautions are necessary to halt further spread of MRSA.

Adult↗
PubMed1997

Advantage of combining resin with lytic BACTEC blood culture media.

The BACTEC 9240 (Becton Dickinson, Sparks, Md.) automated blood culture system is based on the continuous monitoring of CO2 production by means of a fluorescent sensor attached to the bottom of a culture vial. We compared two media for this system, resin-containing Plus aerobic/F and Lytic anaerobic/F. Sets of Plus aerobic/F and Lytic anaerobic/F vials inoculated with similar volumes (9 +/- 2.5 ml) were evaluated. In the laboratory, the vials were introduced into the system in accordance with the recommendations of the manufacturer and incubated at 35 degrees C for 5 days. A total of 10,914 sets consisting of two bottles each were obtained from 3,674 patients (2.97 cultures per patient). Of these, 1,233 (11%) were culture positive, including 1,074 (10%) yielding at least one pathogen, and 178 (2%) were contaminated. A total of 1,135 isolates were considered clinically relevant in 624 septic episodes; we isolated 894 from Plus aerobic/F and 852 from Lytic anaerobic/F (P = 0.06 [not significant]). More S. aureus isolates (P = 0.05), Pseudomonas spp. (P < 0.0001), other gram-negative bacteria (P = 0.004), and yeasts (P < 0.0001) were isolated from Plus aerobic/F medium, but more streptococci (P < 0.0001), E. coli (P = 0.02) strains and anaerobes (P < 0.0001) were detected with Lytic anaerobic/F medium. Lytic anaerobic/F vials were significantly (P < 0.0001) more often positive at least 6 h before Plus aerobic/F vials (n = 112 versus 52, respectively). Significantly more (P < 0.0001) Plus aerobic/F vials (n = 210; 1.9%) than Lytic anaerobic/F vials (n = 42; 0.4%) were unconfirmed positives. Plus aerobic/F and Lytic anaerobic/F proved to be a valuable pair of blood culture media. Plus aerobic/F performs better for patients under antibiotic treatment, due to the antimicrobial-neutralizing effect of resins. For patients without antibiotic therapy, more microorganisms could be isolated from Lytic anaerobic/F due to cell lysis.

Adult↗
PubMed1997

Evaluation of the MB/BacT system and comparison to the BACTEC 460 system and solid media for isolation of mycobacteria from clinical specimens.

The MB/BacT automated system is designed for the isolation of mycobacteria from clinical specimens. It utilizes a colorimetric sensor and reflected light to continuously monitor the CO2 concentration in the culture medium. We compared its performance to that of the BACTEC 12B media for the radiometric BACTEC 460 instrument and that of solid culture media. Respiratory specimens and urine samples were decontaminated with 4% NaOH. The vials of the two instruments were inoculated with 500 microl of sample and two solid egg-based media at 200 microl each. All vials were incubated at 37 degrees C for 6 weeks. A total of 1,078 specimens (633 respiratory specimens, 78 cerebrospinal fluid specimens, 177 other body fluid specimens, 87 urine specimens, and 103 other types of specimens) were cultured in parallel. Mycobacteria could be identified from 73 (6.8%) specimens: 67 M. tuberculosis, 3 M. kansasii, 1 M. xenopi, 1 M. terrae, and 1 mixed M. avium with M. scrofulaceum. Of these, 63 (86.3%) specimens were positive with the MB/BacT system, 67 (91.8%) were positive with the BACTEC 460 instrument, and 58 (79.5%) were positive with the two egg-based media. MB/BacT cultures were positive on average after 17.5 (+/-6.4) days, BACTEC cultures with a growth index of >20 (mean, 200) were positive after 14.3 (+/-8.2) days, and egg-based media were positive after 24.2 (+/-7.5) days. Microorganisms other than mycobacteria contaminated 46 (4.3%) MB/BacT cultures and 31 (2.9%) BACTEC cultures, which had to be discarded. The MB/BacT system is a well-automated system for the detection of M. tuberculosis in clinical specimens without using radioactive reagents. Further trials are required to determine whether it is suitable for the culture of nontuberculous mycobacteria.

Bacterial Typing Techniques↗
PubMed1997

Etiological agents of infectious diarrhea: implications for requests for microbial culture.

Gastrointestinal infections remain a frequent disease worldwide. In order to increase our knowledge of the epidemiology for our patient population, we retrospectively analyzed the results obtained for stool samples received at the clinical microbiology laboratory of the University Hospital of Geneva during a 4-year period. A total of 13,965 specimens from 7,124 patients (1.96 specimens per patient) were cultured, yielding 369 (2.6%) Salmonella spp., 408 (2.9%) Campylobacter spp., and 79 (0.6%) Shigella spp. The cumulative positivity rate of 6.1% decreased to 2.7% when patients received antimicrobial agents (P < 0.001). The positivity rate for 5,912 specimens obtained from patients hospitalized for < or = 3 days was 12.6%, whereas it dropped to 1.4% for patients hospitalized for > 3 days (P < 0.001). Of 3,837 stool samples originating from pediatric patients, 8.8% were positive, and 5.1% of 10,128 samples from adults were positive (P < 0.001). The cytotoxin of Clostridium difficile was detected in 379 of 3,723 samples analyzed (10.2%), and rotaviruses were detected in 190 of 1,601 samples (11.9%). We recommend that the use of cultures for enteric bacterial pathogens be restricted to patients hospitalized for < or = 3 days, with the exceptions of follow-up samples, specimens from immunocompromised patients, and patients whose first sample was culture negative or in the rare event of nosocomial food-borne outbreaks. For patients under antimicrobial therapy, testing for cytotoxin of C. difficile should primarily be requested; this analysis should also be accepted for samples from patients not receiving antimicrobial agents at the time of specimen collection. By applying these restrictions, we could have saved at least $5,000 annually.

Adult↗
PubMed1997

In vitro activity of cefpirome against microorganisms isolated in haematology, oncology and intensive care units in Switzerland.

The in vitro activity of cefpirome, a new parenteral fourth-generation cephalosporin, was investigated in the 5 university hospitals of Switzerland, and compared to 9 other antibiotics mainly used in hospitals, such as ceftazidime, ceftriaxone, cefotaxime, piperacillin, imipenem, gentamicin, vancomycin, ciprofloxacin and ofloxacin. A total number of 992 strains collected only from intensive care units and haematology-oncology units were tested by microdilution according to NCCLS. Cefpirome showed an excellent activity against all Enterobacteriaceae (MIC90 = 4 mg/l), methicillin-susceptible staphylococci (MIC90 = 1 mg/l), Streptococcus pneumoniae (MIC90 = 0.25 mg/l) and Haemophilus influenzae (MIC90 = 0.12 mg/l) isolates. Its activity was superior to that of third-generation cephalosporins against cephalosporinase-depressed mutants of Enterobacter cloacae and Citrobacter freundii isolates (MIC90 > 32 mg/l for third-generation cephalosporins vs 4 mg/l for cefpirome). The MICs of cefpirome of 3 strains of Klebsiella spp. with an extended-spectrum-beta-lactamase were lower (MIC90 = 2 mg/l) than those of third-generation cephalosporins (MICs90 > 32 mg/l). Against Pseudomonas aeruginosa cefpirome was as active as ceftazidime. The activity of cefpirome was poor against methicillin-resistant staphylococci, enterococci and nosocomial Gram-negative bacteria such as Stenotrophomonas maltophilia.

Anti-Bacterial Agents↗
PubMed1996

[Disseminated infection with Mycobacterium celatum].

A 29-year-old patient with AIDS was hospitalized with weight loss, fever and cough. Mycobacterial cultures from sputum, blood and bronchoalveolar lavage became positive after 3 weeks' incubation. When using a DNA probe for identification of Mycobacterium tuberculosis complex, a weakly positive signal was obtained. Tuberculosis was suspected and treatment was started with isoniazid, ethambutol and ciprofloxacin. Sequencing of the gene of the 16S rRNA, however, identified the isolates as belonging to a new, slow-growing atypical mycobacterial species, Mycobacterium celatum (M. celatum). Treatment was modified to take into account the previously described primary resistance of M. celatum to antituberculous drugs, whereupon the patient improved.

AIDS-Related Opportunistic Infections↗
PubMed1996

Effects of antibiotic treatment in the subset of common-cold patients who have bacteria in nasopharyngeal secretions.

BACKGROUND: Upper-respiratory-tract infection is one of the main causes of overuse of antibiotics. We have found previously that bacteria such as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae can be isolated from the nasopharyngeal secretions of a substantial proportion of adults with upper-respiratory-tract infections. We have assessed the efficacy of co-amoxiclav in patients with common colds but no clinical signs of sinusitis or other indications for antibiotics. METHODS: Between January, 1992 and March, 1994, 314 patients who presented to our outpatient clinic with common colds were enrolled in the double-blind, placebo-controlled study. They were randomly assigned 5 days' treatment with co-amoxiclav (375 mg three times daily) or identical placebo. Clinical examinations were done at enrolment and on day 5-7 to assess outcome (cured, persistent symptoms, worse symptoms). Seven patients were excluded after randomisation, seven did not have nasopharyngeal aspiration, and 12 did not return for followup assessment. FINDINGS: Of 300 patients with nasopharyngeal aspirates, 72 had negative bacterial cultures, 167 had cultures positive only for bacteria unrelated to respiratory infections, and 61 had cultures positive for H influenzae, M catarrhalis, or S pneumoniae. At 5-day follow-up of these culture-positive patients, the distribution of outcome was significantly better among co-amoxiclav-treated (n=30) than placebo-treated (n=28) patients (cured 27 vs 4%; persistent symptoms 70 vs 60%; worse symptoms 3 vs 36%; p=0.001). Patients on co-amoxiclav also scored their symptoms significantly lower than patients on placebo (p=0.008). Among culture-negative patients (n=230), the outcome distribution did not differ between the treatment groups (p=0.392). INTERPRETATION: The majority of patients with upper-respiratory-tract infection do not benefit from antibiotics and side-effects are frequent. However, for the subgroup whose nasopharyngeal secretions contain H influenzae, M catarrhalis, or S pneumoniae, antibiotics are clinically beneficial.

Adult↗
PubMed1996

European multicentre evaluation of a commercial system for identification of methicillin-resistant Staphylococcus aureus.

A commercial system for the rapid detection of methicillin-resistant Staphylococcus aureus, the BBL Crystal MRSA test (C-MRSA ID; Becton Dickinson, USA), was evaluated prospectively and compared with a polymerase chain reaction test for the presence of the mecA gene. Ten European centres tested a total of 676 isolates of Staphylococcus aureus from blood cultures. The system correctly identified 661 (97.8%) isolates within 4 h. All but three mecA gene-negative isolates (99.4% specificity) yielded a negative C-MRSA ID reaction, and 158 of 170 mecA gene-positive isolates were accurately detected (92.9% sensitivity). After repeated testing of discrepant results, sensitivity and specificity increased to 99% and 100%, respectively.

Bacteriological Techniques↗
PubMed1996

Susceptibility testing of Haemophilus influenzae--an international collaborative study in quality assessment.

In order to compare the prevalence of antibiotic resistance in different geographical areas, it is necessary to ensure that agreement is achieved between laboratories on the assignment of strains to 'susceptible' and 'resistant' categories. An international quality assessment study, involving 15 laboratories in eight countries, was performed to investigate the standard of performance of the susceptibility testing of Haemophilus influenzae. One hundred and fifty strains of H. influenzae were distributed from the London Hospital Medical College (LHMC) to all laboratories who were asked to test the susceptibility of the strains to ampicillin, chloramphenicol, tetracycline, trimethoprim, cephalosporins and ciprofloxacin. Laboratories were also asked to provide the details of methodology to test the susceptibility. Significant discrepancy between the LHMC and the participating laboratories appeared in the detection of resistance to ampicillin (especially beta-lactamase-negative strains resistant to ampicillin) as well as the assignment of susceptibility and resistance to chloramphenicol, tetracycline and trimethoprim. Often these reflected the use of inappropriate breakpoints which led to erroneous assignment of susceptibility. Other variations including disc content, medium and supplement, inoculum as well as failure to measure zone sizes properly also led to some repeating anomalies.

Ampicillin↗
PubMed1996

Comparative evaluation of BACTEC aerobic Plus/F and Septi-Chek Release blood culture media.

The BACTEC 9240 (Becton Dickinson, Sparks, Md.) automated blood culture system is based on the continuous monitoring of CO2 production by means of a fluorescent sensor attached to the bottom of culture vials. We compared the performance of the BACTEC aerobic Plus/F medium to that of the Septi-Chek Release medium (Becton Dickinson, Sparks, Md.), a manual biphasic blood culture system. Sets consisting of BACTEC aerobic Plus/F and Septi-Chek Release vials inoculated with similar volumes (7 +/- 2 ml) were evaluated. In the laboratory, systems were equipped and analyzed according to the manufacturer's recommendations. The BACTEC and Septi-Chek vials were incubated at 35 degrees C for 5 days. A total of 6,116 compliant sets were obtained from 1,972 adult patients (3.1 cultures per patient). Of these, 731 (12%) were culture positive, including 612 (10%) that yielded at least one pathogen, and 143 (2%) were considered to be contaminated. Of the 672 pathogenic organisms detected, 524 were isolated from the BACTEC aerobic Plus/F medium and 574 were isolated from the Septi-Chek Release medium, 428 organisms grew in both media, 96 organisms grew only in the BACTEC aerobic Plus/F medium, and 146 organisms grew only in the Septi-Chek Release medium (P = 0.001). Haemophilus spp. were isolated more often (P = 0.03) from the BACTEC aerobic Plus/F medium; however, more Streptococcus anginosus organisms (P = 0.02), members of the Enterobacteriaceae family (P < 0.03), and gram-negative anaerobes (P = 0.03) were isolated from the Septi-Chek Release medium. Pathogenic organisms were detected significantly earlier (P < 0.0001) with the BACTEC aerobic Plus/F medium in conjunction with the BACTEC 9240 instrument than with the Septi-Chek Release medium.

Adult↗
PubMed1996

Two different 16S rRNA genes in a mycobacterial strain.

Sequencing of the gene coding for 16S rRNA (16S rDNA) is a well-established method used to identify bacteria, particularly mycobacteria. Unique sequences allow identification of a particular genus and species. If more than one 16S rDNA is present on one mycobacterial genome, their sequences are assumed to be strictly or almost identical. We have isolated a slowly growing Mycobacterium strain, "X", identified by conventional biochemical tests as Mycobacterium terrae. Identification by amplification and direct sequencing of 16S rDNA yielded ambiguous results in two variable regions, suggesting the presence of different copies of the sequenced gene. Total DNA was digested by restriction enzymes and hybridized after Southern blotting to a probe representing about two-thirds of the 16S rDNA. Two copies of 16S rDNA were identified and cloned. By sequencing, the clones were of two different types, A and B, differing in 18 positions. Oligonucleotides specific to each copy of the 16S rDNA were used to distinguish the positions of the two genes observed in the Southern blot. We conclude that Mycobacterium strain "X" has two different copies of 16S rDNA. Variations in the sequence between two copies of 16S rDNA gene have been described in archaeobacteria, but not in mycobacteria. When placed in a phylogenetic tree together with other slowly growing mycobacteria gene A shows a common root with M. terrae, whereas gene B is placed separately.

Cloning, Molecular↗