Atypical Candida strains were isolated from patients in Madagascar, Angola and Germany. These isolates were slow growing and were unable to produce chlamydospores. They had atypical carbohydrate assimilation profiles. All strains were unable to assimilate the amino sugars N-acteylglucosamine and glucosamine as well as the disaccharide trehalose and the organic acid DL-lactate. They were germ-tube-positive in serum, but only some of these organisms produced pseudohyphae after a long incubation. As shown by Fourier transform infrared spectroscopy the atypical Candida isolates clustered as a monophyletic group different from C. albicans and C. dubliniensis. All strains belonged to C. albicans serotype B. Considering all data presented here, this group of Candida strains differs from any other known member of the genus Candida. Therefore, it is suggested to represent a new species within the genus Candida for which the name Candida africana is proposed.

No abstract

Twenty-six hop bitter resins, some hitherto not investigated, were tested for antimicrobial activities. Gram-positive bacteria were much more sensitive than Gram-negative ones. The inhibitory effect against Bacillus subtilis 168 was measured by several methods and the general rule could be established that the antibiotic properties are mainly dependent on the hydrophobic parts of the molecules. Thus the acyl-lupuphenones (2-acyl-3,5-4,4',6-tri(3-methyl-2-butenyl)-cyclohexane-triones (1, 3, 5) having three prenyl and one acyl side chain are the most active substances. Their minimum inhibitory concentration (MIC) increases from the capro (0.5 muM) to the aceto derivative (11 muM). Any substitution with hydrophilic functions or loss of hydrophobic groups causes reductions in biological activity. This is most evident with the corresponding acyl-phloroglucine precursors (2-acyl-1,3,5-trihydroxybenzenes) which lack the three prenyl side chains (MIC, 110 to 5050 muM respectively). Conversion of the central six-membered ring structure into a five-membered one results in additional losses of antimicrobial activity. These findings support the proposal that the lipophilic region of the cell membrane represents the target site for the hop bitter resins.

Descriptive values were determined for eight antifungal agents within the course of a multi-centre study encompassing 1062 German and Austrian clinical yeast isolates. Candida albicans (54%) was the predominant species isolated followed by Candida glabrata (22%), Candida parapsilosis (6%), Candida tropicalis (5.7%), Candida krusei (4.3%), as well as eleven further candidal and four non-Candida yeast species. While 519 (48.9%) isolates were tested susceptible to all antifungals tested, no isolate was found to exhibit complete cross resistance. For C. albicans, the proportions of susceptible isolates were 93.2% (amphotericin B), 95.6% (flucytosine), 84.3% (fluconazole), 83.8% (posaconazole), 91.8% (voriconazole), 96.5% (anidulafungin), 96.2% (caspofungin) and 97.6% (micafungin). Patterns of complete parallel resistances were observed within azoles (8.8%) and echinocandins (1.7%). While a decreased susceptibility was found infrequently for echinocandins and flucytosine, it was more common for azoles with highest proportions for isolates of C. glabrata (fluconazole, 40.6%; posaconazole, 37.2%), Candida guilliermondii (fluconazole and posaconazole, each 25.0%), C. krusei (posaconazole, 28.3%; voriconazole, 60%), C. parapsilosis (fluconazole, 70.3%) and C. tropicalis (fluconazole, 62.3%). The descriptive values obtained in this study represent a valid basis for the comparison of recent and future epidemiological surveys to analyse the susceptibility of yeast isolates towards major antifungal substances.

No abstract