Accuracy and reproducibility of the IDS rapID STR system for species identification of streptococci.

The RapID STR system (Innovative Diagnostic Systems, Inc., Atlanta, Ga.) was evaluated in the identification of 266 streptococci. Organisms included 60 beta-hemolytic streptococci, 71 group D strains (48 enterococci and 23 nonenterococci), 26 Streptococcus pneumoniae, and 109 viridans group strains. With concomitant optochin testing, as is currently recommended by the manufacturer for all alpha-hemolytic strains, the RapID STR system correctly identified 100% of beta-hemolytic strains, 87.3% of group D strains (93.7% of enterococci, 73.9% of nonenterococci), 88.5% of S. pneumoniae, and 72.5% of viridans strains. Without the use of optochin, the correct identification of S. pneumoniae and the viridans group was 26.9 and 52.3%, respectively. The RapID STR system incorrectly identified 3.0% of strains, including four group D streptococci, three pneumococci, and one viridans isolate. Reproducibility was excellent, with 95% of strains tested in triplicate yielding identical results on each of the three occasions. The RapID STR system represents a worthwhile advance in streptococcal species identification, especially for group D and viridans strains.

Effects of diabetes and fasting on pantothenic acid metabolism in rats.

The effects of fasting and diabetes on pantothenic acid (PA) metabolism were studied in rats. Tissue levels of PA and coenzyme A (CoA) and rates of [14C]PA uptake and incorporation into tissue CoA were determined. Both fasting and diabetes resulted in accelerated rates of [14C]PA uptake, higher tissue concentrations of PA, increased incorporation of [14C]PA into CoA, and elevated tissue concentrations of CoA in the liver. The concentration of PA in liver was near the Km of pantothenate kinase for PA in control animals, and increased PA uptake may, in part, account for the increased [14C]PA incorporation into CoA though an elevation in tissue PA levels. In cardiac muscle, increased [14C]PA incorporation into CoA and increased CoA levels were associated with reduced PA uptake and reduced tissue PA levels in both fasting and diabetic animals, suggesting that CoA synthesis is not controlled by substrate availability in this tissue. Uptake of [14C]PA by skeletal muscle was also reduced in diabetic animals. These data suggest that PA uptake by tissues is under metabolic or hormonal control. Decreased uptake by muscle and increased uptake by liver may represent a mechanism for shifting large body stores of PA present in muscle to the liver in which endogenous PA concentrations are normally low. In addition, both fasting and diabetes resulted in decreased urinary PA excretion, a finding that may represent a regulatory mechanism to conserve whole-body PA under these conditions.

Comparative evaluation of the API 20S system and the automicrobic system gram-positive identification card for species identification of streptococci.

Two commercial methods, the API 20S system (API; Analytab Products, Inc., Plainview, N.Y.) and the Gram-Positive Identification Card (GPI; Vitek Systems, Inc., Hazelwood, Mo.), were evaluated without additional tests for the identification of 241 streptococcus strains. Organisms included 60 beta-hemolytic strains, 36 group D strains, 26 Streptococcus pneumoniae strains, and 119 viridans streptococcus strains. API correctly identified to species 68.3% of beta-hemolytic strains, 86.1% of group D strains, 53.9% of S. pneumoniae strains, and 12.6% of viridans streptococci. This method provided excellent identification of group A and B and S. faecalis strains. Overall, API correctly identified 41.9% of strains to species, with 41.1% good likelihood but low selectivity, 15.8% incorrect, and 1.2% not identified. GPI correctly identified to species 58.3% of beta-hemolytic strains, 97.2% of group D strains, 80.8% of S. pneumoniae strains, and 57.2% of viridans streptococci. Group A, B, and D strains were all accurately identified by this system. Overall, GPI correctly identified to species 66.0% of strains, with 8.7% correct preliminary identification, 20.8% incorrect, and 4.6% not identified. Both methods represent a worthwhile advance in streptococcal identification. Neither system, however, can be recommended for species identification of the viridans group at this time.

Screening blood donors for gastrointestinal illness: a strategy to eliminate carriers of Yersinia enterocolitica.

Recent reports of fatal transfusion-associated Yersinia enterocolitica sepsis prompted a study of the feasibility of adding a question to the routine donor health history as a method of reducing this risk. In three American Red Cross blood centers, 11,323 donors were asked one of two questions about gastrointestinal symptoms during their health history screenings. Affirmative responses were obtained from 0.6 or 4.0 percent of the donors, depending on how the question was asked. In one center, more than 6 percent of donors gave affirmative answers. The efficacy of asking a relatively simple question about gastrointestinal symptoms as a way of preventing Y. enterocolitica should be evaluated further, because relatively large numbers of donors may respond affirmatively. Other methods of reducing the risk of transfusion-associated Y. enterocolitica infection should be pursued.