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M Altwegg

Publications and source records attributed to M Altwegg.

At least 91 records · Page 5Linked to original sources
PubMed1993

Ribotyping of Pseudomonas aeruginosa strains isolated from surgical intensive care patients.

To elucidate the sources of Pseudomonas aeruginosa on a surgical intensive care unit, rDNA restriction fragment length polymorphism analysis (ribotyping) was applied to analyze strains isolated during a 4-month prospective study. Samples included 1635 from 153 patients, 2463 from 97 staff members, and 581 from the environment. Only 18 patients were colonized. Isolation from their animate and inanimate environment was very low, with 3 and 2 samples, respectively, being positive. Samples from tap water were negative. Ribotyping could easily distinguish 16 different digest patterns with identical follow-up isolates of the same patient. Horizontal transmission occurred only twice. The discriminatory power of ribosomal DNA in differentiating strains was dependent on the restriction enzymes used; among eight different enzymes, PvuII was the most sensitive, producing 15 different patterns. Ribotyping showed high sensitivity in typing P. aeruginosa isolates and confirmed that colonization occurs from endogenous rather than from exogenous sources.

Animals↗
PubMed1993

Comparison of Rambach agar, SM-ID medium, and Hektoen Enteric agar for primary isolation of non-typhi salmonellae from stool samples.

Stool samples (n = 504) were streaked simultaneously onto Rambach agar (R agar; E. Merck, Darmstadt, Germany), SM-ID medium (bioMérieux S.A., Montalieu-Vercieu, France), and Hektoen Enteric (HE) agar (BBL Becton-Dickinson, Baltimore, Md.) in order to evaluate the performances of the first two media in comparison with that of the well-established HE agar. Following overnight cultivation at 37 degrees C, 29 samples (5.8%) were positive for non-typhi salmonellae on at least one of the three media. Sensitivities and specificities were 69 and 98%, 79 and 85%, and 100 and 79% for R, SM-ID, and HE agars, respectively. On the basis of the poor sensitivities, R and SM-ID agars are not recommended as primary plating media when screening for non-typhi salmonellae. However, the high specificity of R agar may help to reduce the work load when this medium is used for plating after enrichment.

Agar↗
PubMed1993

Isolation of gram-positive rods that resemble but are clearly distinct from Actinomyces pyogenes from mixed wound infections.

Beginning in 1990, gram-positive rods resembling Actinomyces pyogenes were found with increasing frequency in mixed cultures from various infectious processes, most of them from patients with otitis, empyema, pilonidal cysts, perianal abscesses, and decubitus ulcers. Ribotyping and hybridization showed that these gram-positive rods could be divided into five groups not related to known Actinomyces species. Biochemical markers for reliable differentiation into these groups, however, could not be found. Therefore, naming new species is not warranted unless parameters are discovered that allow identification without DNA hybridization. These gram-positive rods have been isolated only in mixed cultures with anaerobes, Staphylococcus aureus, Streptococcus "milleri," enterococci, and gram-negative rods. Their exact role in these possibly synergistic infections needs further investigation.

Adult↗
PubMed1993

Isolation of Escherichia fergusonii from four different sites in a patient with pancreatic carcinoma and cholangiosepsis.

Escherichia fergusonii was isolated from a 69-year-old male with pancreatic carcinoma and cholangiosepsis from gallbladder fluid, three blood cultures, feces, and a superficial wound of the abdomen. Biochemical reactions, antimicrobial susceptibility patterns, susceptibility to polyvalent phage 0-1, and rRNA gene restriction analysis suggested that the four strains were of clonal origin. Our data indicate that E. fergusonii possesses a pathogenic potential in humans.

Aged↗
PubMed1992

[Bacterial pathogens in diarrhea: demonstration of verotoxin-producing Escherichia coli using the polymerase chain reaction].

In 23% of 576 diarrhea patients we were able to demonstrate putative bacterial pathogens. Not included in this number is Clostridium difficile which was found in 8 of 48 (8.3%) specimens analyzed. In addition to Salmonella (8.2%), Campylobacter (6.0%), Aeromonas (2.7%), Shigella (1.9%) and Yersinia (0.8%) we identified verotoxin-producing Escherichia coli (VTEC) in 10 patients (1.9%). VTEC were found as frequently as Shigella (occurring exclusively in patients returning from the tropics) and we propose that VTEC should be routinely assayed in patients with travel-associated diarrhea as well as in those with diarrhea presumably acquired in Switzerland. Established methods for identification of E. coli O157:H7, which include screening for sorbitol-negative Enterobacteriaceae and agglutination, are laborious and insensitive (only 1 of 10 patients with proven VTEC infection positive). The other 9 patients were identified by means of the polymerase chain reaction (PCR). In 7 of these 9 patients we were able to isolate a verotoxigenic strain following a positive PCR result by screening large numbers of colonies. None of them belonged to the O157:H7 serogroup and, in addition, all were sorbitol-positive. The polymerase chain reaction as performed in this study is easy to use, is applicable to large numbers of specimens, and can be regarded as the method of choice for demonstration of VTEC in the clinical diagnostic laboratory.

Adult↗
PubMed1992

rRNA gene restriction patterns as taxonomic tools for the genus Aeromonas.

In the genus Aeromonas there are at least 13 DNA hybridization groups, which are difficult to differentiate biochemically. We investigated the usefulness of rRNA gene restriction patterns for characterization and identification of the various groups. Genomic DNA was digested with restriction endonuclease SmaI, transferred to a nylon membrane, and hybridized with biotinylated plasmid pKK3535 containing the rrnB operon of Escherichia coli. The SmaI bands at 0.8 to 4 kb but not those at positions corresponding to sizes larger than 4 kb showed a good correlation with hybridization groups, allowing identification of strains to the level of genetic species. We demonstrated that the 567-bp fragment localized between positions 80 and 647 of the 16S ribosomal gene of E. coli was essential for hybridization to the low-molecular-weight fragments, whereas the remainder of the operon did not hybridize to these fragments. On the basis of these results, we concluded that the Aeromonas chromosome contains multiple rRNA operons which may be used for species identification.

Aeromonas↗
PubMed1992

Genetic variation among Malaysian isolates of Salmonella typhi as detected by ribosomal RNA gene restriction patterns.

Genetic variation among Malaysian isolates of Salmonella typhi was determined by analysis of ribosomal RNA gene restriction patterns. Of the 20 isolates analyzed, eight different pattern combinations were detected. The amount of variation observed was also dependent upon the restriction endonuclease used; PstI produced more different patterns than did SmaI. The results suggested that disease activity was due to a number of different clones circulating simultaneously rather than a single strain. Further implications of the data are discussed.

DNA, Ribosomal↗
PubMed1992

Numerical classification and identification of Aeromonas genospecies.

A total of 176 Aeromonas strains representing all currently characterized genospecies were tested for 329 biochemical characters. Overall similarities of all strains were determined by numerical taxonomic techniques, the UPGMA algorithm and the SSM and the SJ coefficients as measures of similarity. Sixteen clusters (two or more strains) and seven unclustered strains were recovered at the 93.5% similarity level (SSM). Genospecies 1, 4, 5, 6, 7, 9, 12 and 13 were largely represented by single phena, whereas strains of genospecies 2 and 3 were found in closely-related phena. Strains belonging to genospecies 8 formed two distinct biotypes. Strains belonging to genospecies 11 formed a subcluster within a cluster representing different genospecies. In general, similar groupings were obtained with the Jaccard coefficient at a similarity level of 80.0% (SJ) with minor changes in the definition of clusters. The phenetic data showed good correlation with the taxa defined by DNA/DNA hybridization and those obtained by multilocus enzyme analysis. For all genospecies (independent from cluster assignment) 30 diagnostic characters were selected to construct a matrix for probabilistic identification. The correct identification rate of the matrix was 71.51% taking a Willcox probability greater than 0.99, and 83.7% taking a Willcox probability greater than 0.9 as identification threshold levels.

Aeromonas↗
PubMed1992

Application of ribotyping for differentiating aeromonads isolated from clinical and environmental sources.

We have investigated the usefulness of ribotyping for the differentiation of aeromonads isolated from five patients with gastroenteritis and from the source water, treatment plant, and distribution system of a small public water supply. Aeromonas hydrophila and Aeromonas caviae were isolated from fecal specimens preserved in Cary-Blair transport medium by using blood ampicillin agar or alkaline peptone water (pH 8.4) subcultured to blood ampicillin agar plates. A. hydrophila, Aeromonas sobria, and A. caviae were isolated from duplicate 100-ml water samples by the membrane filter technique by using ampicillin dextrin agar for quantitative determination of growth and alkaline peptone water enrichment for detection of the presence or absence of aeromonads below the detection limit of the membrane filter method. In addition, free chlorine residuals and pH values were determined for all water samples and heterotrophic plate counts and total and fecal coliform analyses were performed on them. Ribotyping patterns of aeromonads recovered from well 1, detention basin, sand filter, softener, and distribution samples were compared with those of the five clinical isolates. All patient strains were unique; however, identical ribotypes of A. hydrophila and A. sobria isolated from multiple sites in the water system indicated colonization of a well, sand filters, and the softener, with the potential for sporadic contamination of distribution water. Plant operational deficiencies were noted and corrected. Ribotyping can effectively differentiate otherwise indistinguishable strains of bacteria, thus providing a powerful tool for investigation of waterborne diseases and bacteriological problems within water treatment plants and distribution systems.

Aeromonas↗
PubMed1992

Siderophore production and DNA hybridization groups of Aeromonas spp.

A correlation between the genospecies (DNA-DNA hybridization group) and the type of siderophore produced by 118 isolates of the genus Aeromonas was established. Organisms in hybridization groups 1 through 5 (including 5A, 5B, and 5AB) and group 12 predominantly produced the siderophore amonabactin, while an enterobactinlike siderophore was prevalent in groups 8/10 and 9. The siderophore produced by strains in group 6 may be an as-yet-unidentified nonphenolate, nonhydroxamate compound, and group 7 isolates synthesized no siderophores. Determination of the indigeneous siderophore (or the absence of one) produced by an isolate of the genus Aeromonas may assist in identification of the organism's genetic species and may suggest the presence of certain virulence properties.

Aeromonas↗
PubMed1991

Media and methods for isolation of aeromonads from fecal specimens. A multilaboratory study.

An international multilaboratory study was conducted to establish the optimal combination of culture media, incubation time and temperature for recovery of aeromonads from stools using blood ampicillin (10 mg/l) agar (BAA), starch ampicillin (10 mg/l) agar (SAA), and cefsulodin irgasan novobiocin agar (CIN) with alkaline peptone water (APW) for enrichment. Optimal recovery of aeromonads (167/186) occurred using BAA (37 degrees C; 24 h) and CIN (25 degrees C; 48 h) with APW (25 degrees C; 24 h) subcultured to BAA (37 degrees C; 24 h) and CIN (25 degrees C; 48 h).

Aeromonas↗
PubMed1991

[The problems of rapid diagnosis of Clostridium difficile as causative agent of antibiotic-associated pseudomembranous colitis].

This paper compares three common methods for the detection of Clostridium difficile, i.e. latex agglutination, culture and cytotoxic activity. The sensitivity of the latex agglutination test alone is 70%, of the culture 100% and of the cytotoxin test 66%. Specificities are 93, 96 and 100%, respectively. The latex agglutination has positive and negative predictive values of 58 and 96%; the respective values for the culture are 77 and 100%, for the cytotoxin assay 100 and 96%. Whereas all tests are fairly reliable for the exclusion of diarrhea associated to Clostridium difficile (CAD), the positive predictive values of latex agglutination and culture are too low. If one requests two positive test results for proof of CAD, about two third of all cases are detected by any combination of laboratory tests, while the specificity approaches 100%. We recommend that two of the three tests are performed; the choice is influenced by the possibilities of the laboratory.

Bacterial Proteins↗
PubMed1991

Development of resistance to quinolones in five patients with campylobacteriosis treated with norfloxacin or ciprofloxacin.

Development of resistance to nalidixic acid, norfloxacin and ciprofloxacin was observed in five patients with Campylobacter jejuni or Campylobacter coli infection. From all these patients nalidixic acid- and quinolone-susceptible strains were isolated initially, whereas after therapy with norfloxacin or ciprofloxacin strains resistant to these antibiotics were found. Campylobacter strains from the same patient always belonged to the same species and, with the exception of one case, showed identical rRNA gene restriction (rDNA) patterns. This indicates that double-infection with a susceptible and a resistant strain was not responsible for the phenomenon but rather that the infecting strain rapidly developed resistance following treatment.

Adult↗