Identification of gram-positive coccal and coccobacillary vancomycin-resistant bacteria.
A total of 84 of 150 vancomycin-resistant (defined as no inhibition of bacterial growth around a 30-micrograms vancomycin disk placed on 5% sheep blood-Trypticase soy agar [BBL Microbiology Systems, Cockeysville, Md.]) bacteria were definitively identified by determining the phenotypic criteria. The identity of representatives was also confirmed by DNA-DNA hybridizations. The following strains were identified: 1 Enterococcus faecium, 18 Leuconostoc mesenteroides, 15 Leuconostoc citreum, 9 Leuconostoc pseudomesenteroides, 2 Leuconostoc lactis, 20 Pediococcus acidilactici, 5 Pediococcus pentosaceus, and 14 Lactobacillus confusus. The remaining vancomycin-resistant strains were identified as probable Leuconostoc (6 strains), probable Pediococcus (1 strain), and probable lactobacilli (28 strains). A total of 32 strains of gram-positive coccobacillary bacteria remained unidentified. Tests used for the phenotypic identification of strains to the genus level included a Gram stain of bacteria grown in thioglycolate broth, gas production in Lactobacillus Mann, Rogosa, and Sharpe broth, hydrolysis of pyrrolidonyl-beta-naphthylamide, bile-esculin reaction, demonstration of streptococcal group D antigen, and growth at 10 and 45 degrees C and in 6.5% NaCl broth. Strains were identified to the species level by hydrolysis of esculin, reactions in litmus milk, slime production on 5% sucrose agar, acidification of maltose, melibiose, and raffinose broths, deamination of arginine, and growth at 42 degrees C and in 6.5% NaCl broth.
Facklam
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Division of Bacterial Diseases, Centers for Disease Control, Atlanta, Georgia 30333.
Hollis
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Collins
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MD
D002374:Catalase / Q000378:metabolism; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests; D009693:Nucleic Acid Hybridization; D010641:Phenotype; D013045:Species Specificity; D013289:Streptococcaceae / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology*
D004269:DNA, Bacterial; D014640:Vancomycin; D002374:Catalase