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Biomedical subjects

A Wenger

Publications and source records attributed to A Wenger.

27 records · Page 2Linked to original sources
PubMed1989

[Disseminated nocardiosis due to Nocardia brasiliensis in an ambulatory patient].

We report the case of a 76-year-old man with generalized nocardiosis. The microbiologic pattern, the different clinical manifestations and the treatment of nocardiosis are discussed in general. In the particular case of our patient the disease manifested itself primarily as a subcutaneous abscess, a metastasis secondary to pulmonary nocardiosis. The disease was caused by a Nocardia brasiliensis, which is rarely seen in Europe and which does not usually cause a generalized form of nocardiosis.

Abscess↗
PubMed1989

Evaluation of the Cobas-Bact system for direct and rapid identification and antimicrobial susceptibility testing of Enterobacteriaceae from positive urine specimens.

A direct antimicrobial susceptibility test and a direct identification of Gram-stained urine specimens positive for Enterobacteriaceae using a new instrument (Cobas-Bact) were compared by means of the conventional Kirby-Bauer agar diffusion disk method and the spot indole test, an in-house set of identification tests or API 20E. Bacteria from 191 cases of monomicrobial bacteriuria due to members of the family Enterobacteriaceae were tested. Direct susceptibility testing was performed in 180 cases (94%), providing 1649 antibiotic-microorganism combinations. A complete agreement was reached in 82% and essential agreement in 92% of cases. Minor discrepancies were found in 163 (9.9%) major ones in 125 (7.6%) and very major ones in 10 (0.6%) of examinations. 72% of all minor and 71% of all major discrepancies were caused by two antibiotics: cephalothin and nitrofurantoin. Of the very major discrepancies, 50% were due to amoxicillin. Of 171 direct identifications obtained, 130 (76%) were "high-confidence" correct identifications (percentage of likelihood p greater than or equal to 80%), 25 (14.6%) "low-confidence" identifications (percentage of likelihood p less than 80%) and 16 (9.4%) misidentifications. On the whole, this direct and rapid Cobas-Bact identification and susceptibility testing procedure provided satisfying information within 5-6 h after collection of urine specimens positive for members of the Enterobacteriaceae family.

Anti-Bacterial Agents↗
PubMed1989

Evaluation of the Cobas-Bact system for direct and rapid identification and antimicrobial susceptibility testing of gram-negative rods from positive blood culture broths.

A direct antimicrobial susceptibility test and a direct identification of positive blood culture broths for gram-negative rods confirmed with Gram stain by using a new instrument, Cobas-Bact, were compared with the conventional Kirby-Bauer agar diffusion disk method and with the in-house set of identification or API 20E, respectively. The bacterial pellet of centrifuged positive blood culture broth was used to inoculate a Cobas-Bact susceptibility and identification rotor. Bacteria from 206 cases of monomicrobial septicemia due to members of the family Enterobacteriaceae were tested. In 198 episodes (96%), direct identification and antimicrobial susceptibility testing results were obtained for the same bacterial pathogen within 5 h of detection. Of 204 direct identifications obtained, 177 (86.6%) were "high-confidence" correct identifications (percentage of likelihood [P] greater than or equal to 80%) and 25 (12.5%) "low-confidence" correct identifications (P less than 80%), whereas only 2 misidentifications occurred (1 Escherichia coli and 1 Proteus mirabilis). Direct susceptibility testing was performed in 199 episodes (96%), providing 1,885 antibiotic-microorganism combinations. Full agreement reached 86.3%, and essential agreement reached 92.8%. Minor discrepancies were found in 120 (6.5%) of the tests, major discrepancies were found in 127 (6.8%) tests, and very major discrepancies were found in only 7 (0.4%) tests. Subsequent MIC determinations in cases of major or very major discrepancies reduced the number of major discrepancies involving cephalosporins from 60 to 16, whereas all those involving aminoglycosides remained. Overall, this direct and rapid Cobas-Bact identification and susceptibility testing procedure offered accurate information with 5 to 6 h after the laboratory detection of bacteremia and septicemia due to members of the Enterobacteriacease.

Bacteriological Techniques↗
PubMed1987

Evaluation of a small "conventional" identification system for fermentative gramnegative rods using a computerized data base.

A small "conventional" identification system consisting of six tubed media totalling eleven reactions was used to identify 467 strains of Enterobacteriaceae, 15 strains of Aeromonas sp., and 3 strains of Plesiomonas shigelloides. The system identified 371 strains (76.5%) correctly to maximum identification (species or genus) level and an additional 13 strains (2.7%) to genus level where species level identification would have been possible. Ninety strains (18.6%) were not identified. Only 11 strains (2.3%) were misidentified. The system is inexpensive compared with commercial systems and can be used for primary identification of fermentative gramnegative bacteria in a clinical microbiology laboratory. It comes with a computerized data base in the form of an identification manual.

Aeromonas↗
PubMed1987

Cobas-Bact system for identification of members of the family Enterobacteriaceae in 4 h 20 min.

The Cobas-Bact (Roche Diagnostics, Basel, Switzerland) new rotor for the identification (ID) in 4 h 20 min of 33 members of the family Enterobacteriaceae to genus and species level was evaluated by testing 444 strains of which 398 belonged to common species and 46 belonged to rare species of Enterobacteriaceae. Each strain was identified by the API 20E system (Analytab Products, Plainview, N.Y.), and additional discriminating tests were set up if necessary. Only first-choice ID were considered in this study and were classified either as high-confidence ID (normalized likelihood, greater than or equal to 80%) or as low-confidence ID (normalized likelihood, less than 80%) requiring additional tests for confirmation. The data were analyzed by two versions of Cobas-Bact software. With the first version of the software (SW8446), the overall accuracy of Cobas-Bact was 95.5% (424 correct ID of 444). When restricted to high-confidence ID it rose to 99.4% (350 of 352) for the common species and 96.9% (31 of 32) for the rare species. Only three strains of the high-confidence group were misidentified. Sixty ID were considered unacceptable because of their low confidence. Using the first software version (SW8446) they represented 12% (46 of 398) of the common species (17 typical strains, 10 Shigella species, 10 inactive Escherichia coli strains, and 9 rare biotypes) and 30% (14 of 46) of the rare species. The same data analyzed by the new version (SW8524) of the Cobas-Bact software resulted in an overall accuracy of 93.9% (417 correct ID). The number of high-confidence ID rose to 401, of which 392 (97.7%) were accurate. The decrease in low-confidence ID (43 versus 60) was mainly due to the Shigella species. In conclusion the accuracy of Cobas-Bact identification system was very good when restricted to high-confidence ID. The Cobas-Bact performance for rare species ID was poorer, but the small number of strains tested does not allow definitive conclusions.

Bacteriological Techniques↗
PubMedDate not supplied

Age and growth factors in porcine full-thickness wound healing.

It has been recognized that the rate of cutaneous wound healing declines with age, yet the molecular processes that affect this decline remain poorly understood. The purpose of this study was to compare reepithelialization and contraction rates, and growth factor profiles in full-thickness wounds in swine of various ages. Multiple full-thickness excisional wounds were created on the dorsum of 24-month-old (n=2), 4-month-old (n=2), and 2-month-old (n=2) Yucatan Minipigs. The extent of reepithelialization was shown to decrease with increasing age in a manner that was statistically significant among the 2-month-old (79%), 4-month-old (48%), and 24-month-old pigs (22%). Enzyme-linked immunosorbent assay results showed that endogenous vascular endothelial growth factor concentrations in the 2- and 4-month-old animals peaked on day 4, reaching levels of 482 pg/ml and 420 pg/ml, respectively. In the 24-month-old pigs the vascular endothelial growth factor concentration peaked later (day 6), and was present at a lower level (229 pg/ml). On day 4 the vascular endothelial growth factor levels in the older pigs reached only 120 pg/ml, representing a four-fold decrease in concentration compared to the younger pigs. A comparison of platelet-derived growth factor-BB concentrations across the age groups showed similar patterns in the 2- and 4-month-old pigs (peaks of 77 and 91 pg/ml on days 2 and 3, respectively), and levels in the 24-month-old were below the sensitivity level (31.5 pg/ml) of the assay. Transforming growth factor-beta1 levels across the age groups did not differ in a manner that was statistically significant, and all age groups peaked on day 9. Wound contraction showed no statistical differences among the age groups from days 3 to 9. On day 11, however, wound contraction in 2-month-old pigs was about 10% faster than in 24-month-old pigs (p < 0.05). These data suggest a possible new algorithm for treating wounds in aged skin, by which exogenous growth factors can be added to the wound microenvironment in doses and at times that match the growth factor profiles observed in wounds made in younger skin.

Age Factors↗
PubMedDate not supplied

Modulation of in vitro angiogenesis in a three-dimensional spheroidal coculture model for bone tissue engineering.

One of the major challenges in tissue engineering of bone substitutes remains vascularization of the transplant. We have developed a three-dimensional collagen-based coculture system to assess interactions between human endothelial cells (hECs) and human osteoblasts (hOBs) in vitro. Human umbilical vein endothelial cells (HUVECs) were grown as three-dimensional multicellular spheroids and seeded in a collagen matrix to assess sprouting of the spheroids, that is, formation of tubelike structures resembling early capillaries. Direct cell contact between hOBs and HUVECs was established by incorporating hOBs into the EC spheroids, thus forming heterogeneous cospheroids. Spatial organization of cospheroids and sprout configuration were assessed by immunohistochemical wholemount staining techniques and confocal laser microscopy. Cumulative sprout length of spheroids was quantitatively analyzed by digital imaging planimetry. In this model HUVECs and hOBs formed heterogeneous cospheroids with distinct spatial organization. The ability of HUVEC spheroids to form tubelike structures on angiogenic stimulation with vascular endothelial growth factor and basic fibroblast growth factor was suppressed in heterogeneous HUVEC/hOB cospheroids. The model system introduced in this study may be useful to assess the mechanisms involved in regulating angiogenesis during bone formation and to further investigate the mechanisms by which heterotypic cell-cell interactions inhibit endothelial tube formation for applications in bone tissue engineering.

Bone Substitutes↗