A new fluorescence in situ hybridization (FISH) method with peptide nucleic acid (PNA) probes for identification of Staphylococcus aureus directly from positive blood culture bottles that contain gram-positive cocci in clusters (GPCC) is described. The test (the S. aureus PNA FISH assay) is based on a fluoresceinlabeled PNA probe that targets a species-specific sequence of the 16S rRNA of S. aureus. Evaluations with 17 reference strains and 48 clinical isolates, including methicillin-resistant and methicillin-susceptible S. aureus species, coagulase-negative Staphylococcus species, and other clinically relevant and phylogenetically related bacteria and yeast species, showed that the assay had 100% sensitivity and 96% specificity. Clinical trials with 87 blood cultures positive for GPCC correctly identified 36 of 37 (97%) of the S. aureus-positive cultures identified by standard microbiological methods. The positive and negative predictive values were 100 and 98%, respectively. It is concluded that this rapid method (2.5 h) for identification of S. aureus directly from blood culture bottles that contain GPCC offers important information for optimal antibiotic therapy.
Several life history hypotheses for the American eel, Anguilla rostrata, were examined using seaward-migrating silver-phase eels collected in the Annaquatucket River, Rhode Island, U.S.A. Female eels were significantly larger and older than males. Female eels also had a significantly higher mean growth rate. The addition of life history data from Annaquatucket River eels to published silver eel data from locations throughout the eels' range shows that female size at migration is positively correlated with latitude (r = 0.56, p = 0.05) but male size is not (r = 0.54, p = 0.17). Female age was not related to latitude (r = 0.57, p = 0.27) but male age showed a positive relationship (r = 0.87, p = 0.05). Growth rates for females and males were inversely related to latitude (r = -0.98, p = 0.02 and r = -0.95, p = 0.05, respectively). Differences between the latitudinal relationships and life history traits of the sexes may be due to differences in life history strategies.
A new fluorescence in situ hybridization (FISH) method that uses peptide nucleic acid (PNA) probes for identification of Candida albicans directly from positive-blood-culture bottles in which yeast was observed by Gram staining (herein referred to as yeast-positive blood culture bottles) is described. The test (the C. albicans PNA FISH method) is based on a fluorescein-labeled PNA probe that targets C. albicans 26S rRNA. The PNA probe is added to smears made directly from the contents of the blood culture bottle and hybridized for 90 min at 55°C. Unhybridized PNA probe is removed by washing of the mixture (30 min), and the smears are examined by fluorescence microscopy. The specificity of the method was confirmed with 23 reference strains representing phylogenetically related yeast species and 148 clinical isolates covering the clinically most significant yeast species, including C. albicans (n ؍ 72), C. dubliniensis (n ؍ 58), C. glabrata (n ؍ 5), C. krusei (n ؍ 2), C. parapsilosis (n ؍ 4), and C. tropicalis (n ؍ 3). The performance of the C. albicans PNA FISH method as a diagnostic test was evaluated with 33 routine and 25 simulated yeast-positive blood culture bottles and showed 100% sensitivity and 100% specificity. It is concluded that this 2.5-h method for the definitive identification of C. albicans directly from yeast-positive blood culture bottles provides important information for optimal antifungal therapy and patient management.
Many wildlife populations are declining at rates higher than can be explained by known threats to biodiversity. Recently, thiamine (vitamin B1) deficiency has emerged as a possible contributing cause. Here, thiamine status was systematically investigated in three animal classes: bivalves, ray-finned fishes, and birds. Thiamine diphosphate is required as a cofactor in at least five life-sustaining enzymes that are required for basic cellular metabolism. Analysis of different phosphorylated forms of thiamine, as well as of activities and amount of holoenzyme and apoenzyme forms of thiamine-dependent enzymes, revealed episodically occurring thiamine deficiency in all three animal classes. These biochemical effects were also linked to secondary effects on growth, condition, liver size, blood chemistry and composition, histopathology, swimming behaviour and endurance, parasite infestation, and reproduction. It is unlikely that the thiamine deficiency is caused by impaired phosphorylation within the cells. Rather, the results point towards insufficient amounts of thiamine in the food. By investigating a large geographic area, by extending the focus from lethal to sublethal thiamine deficiency, and by linking biochemical alterations to secondary effects, we demonstrate that the problem of thiamine deficiency is considerably more widespread and severe than previously reported.
A new fluorescence in situ hybridization method using peptide nucleic acid (PNA) probes for identification of Brettanomyces is described. The test is based on fluorescein-labeled PNA probes targeting a species-specific sequence of the rRNA of Dekkera bruxellensis. The PNA probes were applied to smears of colonies, and results were interpreted by fluorescence microscopy. The results obtained from testing 127 different yeast strains, including 78 Brettanomyces isolates from wine, show that the spoilage organism Brettanomyces belongs to the species D. bruxellensis and that the new method is able to identify Brettanomyces (D. bruxellensis) with 100% sensitivity and 100% specificity.Brettanomyces is a well-recognized wine spoilage yeast that causes an undesirable flavor. The sensory character of this "Bretty" flavor is often described as mousiness, barnyard, horse sweat, or Band-Aid (5, 9). Current methods for identification and enumeration of Brettanomyces contamination take 1 to 2 weeks and rely on growth on a semiselective culture medium, followed by final identification by biochemical and physiological analysis and morphology as determined by microscopic examination (3). Morphological characterization of Brettanomyces is somewhat subjective, and there have been various morphological descriptions, such as bud scars, bullet shape, and Mickey Mouse-like. Newer techniques for rapid detection and identification of Brettanomyces, such as an enzyme-linked immunosorbent assay (7) and, more recently, PCR (6), have also been described.The nomenclature of Brettanomyces used in the wine industry differs from that of the recently revised taxonomy of yeasts (11,12). Enologists refer to the spoilage organism as Brettanomyces or "Brett" or, in some publications, by the species names Dekkera intermedia and Brettanomyces intermedius (3), Brettanomyces lambicus (3), Brettanomyces custersii, or Dekkera bruxellensis (6). Today, only D. bruxellensis is an accepted species name, and the other names are considered synonyms.Peptide nucleic acid (PNA) molecules are pseudopeptides which are able to hybridize to complementary nucleic acid targets (RNA and DNA) obeying Watson-Crick base pairing rules (2, 10). Due to their uncharged, neutral backbone, PNA probes exhibit favorable hybridization characteristics, such as high specificity, strong affinity, and rapid kinetics resulting in improved hybridization to highly structured targets, such as rRNA (13). In addition, the relatively hydrophobic character of PNAs compared to DNA oligonucleotides makes PNA probes capable of penetrating the hydrophobic cell wall following mild fixation conditions that do not lead to disruption of cell morphology (14). These unique characteristics of PNA have opened new possibilities for molecular diagnostic assays.The D1-D2 region of 26S ribosomal DNA (rDNA) of eucaryotic organisms shows a high degree of species variation and has been used for identification and taxonomy of yeast species (1,8). In this study, 26S rDNA sequence information was used to design speci...
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