Biomedical subjects
Publications and source records attributed to J Wüst.
The minimum inhibitory concentrations of penicillin and cephalothin necessary to inhibit growth of most anaerobic bacteria were reduced to a susceptible level by 1 to 5 mug of clavulanic acid per ml. In most cases, minimum inhibitory concentrations of cefoxitin were not affected.
The minimal inhibitory concentrations (MICs) of sulfamethoxazole and trimethoprim against 144 strains of obligately anaerobic bacteria were determined on Diagnostic Sensitivity Test agar (Oxoid) or in prereduced Diagnostic Sensitivity Test broth, both supplemented with sodium pyruvate (1 mg/ml), hemin (5 mug/ml), and vitamin K(1) (1 mug/ml). Fifty-eight percent of the strains were susceptible to sulfamethoxazole alone (MIC </= 16 mug/ml), only 12% were susceptible to trimethoprim alone (MIC </= 1 mug/ml), and 85% were susceptible to the combination of sulfamethoxazole plus trimethoprim (MIC </= 16 mug/ml) at a ratio of 19:1. All 45 strains of the Bacteroides fragilis group were susceptible to the combination. Synergy of the combination was often observed by a checkerboard MIC determination of 123 strains, usually most markedly when the ratio of the two components was near 1:1. However, there was also synergism at the ratio of sulfamethoxazole to trimethoprim of 16:1 in 61 (53.5%) of the 114 strains that could be evaluated for synergistic activity. When the strains were tested by the broth-disk test proposed by Wilkins and Thiel, modified by using prereduced Diagnostic Sensitivity Test broth instead of brain heart infusion broth and by using a smaller inoculum, there was over 90% correlation with the MICs. Poor results were found when the broth-disk tests were performed in brain heart infusion broth. There was very poor correlation between inhibition zone diameters by an agar diffusion method and MICs.
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By quantitative gas-liquid chromatography of glucose-containing blood cultures at the moment of first signs of growth, a presumptive diagnosis of anaerobic bacteremia could be made in 24 out of 26 cultures yielding obligate anaerobes upon subsequent culture. With Bacteroides sp. (20 strains isolated), elevated levels of isovaleric acid (greater than or equal to 0.1 mumol/ml) and/or succinic acid (greater than or equal to 5 mumol/ml) were detected in the medium used. An exception to this were two strains of Bacteroides thetaiotaomicron that did not produce sufficient quantities of these acids. In the case of butyrate-producing gram-positive cocci (four strains), butyric acid in amounts of greater than or equal to 0.8 mumol/ml was detected. Propionibacteria (five strains) produced propionic acid in amounts of greater than or equal to 3.9 mumol/ml. No false positive results were found in 103 blood cultures with growth of aerobic or facultatively anaerobic bacteria only.
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A genetic analysis of resistance to antibiotics in methicillin-resistant Staphylococcus aureus was performed. Demonstration of plasmid-specific DNA either in transductants that had received antibiotic-resistance markers from multiply-resistant strains, or in segregants of methicillin-resistant strains that had lost unstable determinants except the one under study, indicated that markers of resistance to penicillin, chloramphenicol and neomycin are present on separate, mutually compatible plasmids. Absence of covalently closed circular DNA was demonstrated in transductants that were resistant to methicillin, tetracycline, erythromycin and streptomycin, as well as in segregants that had lost the penicillinase, chloramphenicol and neomycin plasmid, but were still resistant to methicillin, tetracycline, erythromycin, streptomycin and the sulphonamides. Analysis of plasmid DNA either in a 5-20% neutral sucrose gradient or by electron microscopy revealed the presence of three readily distinguishable plasmids. The molecular weights of these plasmids were estimated by comparing the sedimentation rate constants with those of known reference plasmids and by contour-length measurements. The molecular weight of the penicillinase plasmid was estimated to be 20 X 10(6) daltons, that of the chloramphenicol plasmid 3 X 10(6) daltons and that of the plasmid carrying the neomycin resistance marker 37 X 10(6) daltons.
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Elimination and transduction of drug resistance was examined in methicillin-resistant strains of Staphylococcus aureus. Irreversible spontaneous loss and "curing" by aging of cultures and by treatment with ethidium bromide indicated that the determinants for penicillinase production and chloramphenicol resistance, and probably also for neomycin resistance, were located extrachromosomally. On the other hand, the determinants of resistance to erythromycin, streptomycin, tetracycline, and methicillin could not be eliminated by acridines, ethidium bromide, rifampin, sodium dodecyl sulfate, ultraviolet (UV) irradiation, growth at 43.5 C, aging of cultures, or combinations of these treatments. The stimulation of transduction frequency by UV irradiation of phage in the case of the stable markers, but not in the case of the unstable ones, supported further the hypothesis of chromosomal location of the markers of methicillin, erythromycin, tetracycline, and streptomycin resistance and extrachromosomal location of the determinants for penicillinase production and chloramphenicol resistance. Neomycin resistance could not be transduced. Joint elimination and co-transduction of the determinants for penicillinase production and resistance to chloramphenicol and neomycin were not observed, indicating the location of these markers on separate, mutually compatible plasmids. Co-transduction of chromosomal resistance determinants was usually less than 1%, which makes the location of these genes in a circumscribed area of the chromosome improbable.
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An unusual case of Yersinia pseudotuberculosis septicemia is reported. Diabetes mellitus was the sole underlying disease; liver enzyme elevations were only transitory. The strain did not show motility until after 50 days at room temperature; it showed temperature and media-dependent fermentation of arabinose, melibiose and rhamnose.
We describe a 35-year-old man with disseminated actinomycosis due to Actinomyces meyeri and treated successfully with penicillin. To our knowledge this is the first case report of a generalized infection due to this species, involving lung, intra- and retroperitoneal organs.
A comparison was made between the Septi-Chek "Release" system containing saponins, standard BacT/Alert blood culture bottles and FAN BacT/Alert blood culture bottles for culturing CAPD fluids. Seventy-seven CAPD effluent specimens were tested. No differences could be found. Therefore, lytic agents are not necessary when dialysates are cultured in blood culture media.