Evaluation of three disk tests for identification of enterococci, leuconostocs, and pediococci

Abstract

Simple rapid tests for presumptive identification of catalase-negative non-beta-hemolytic cocci (i.e., enterococci, leuconostocs, and pediococci) have not previously been available. Seven hundred thirty-four strains of aerobic and facultatively anaerobic, catalase-negative, non-beta-hemolytic gram-positive cocci were tested for susceptibility to vancomycin (Van s) by a screening procedure and production of leucine aminopeptidase (LAPase) and pyrrolidonylarylamidase (PYRase) in disk tests. Three unique patterns of activity in response to the three disks (30 g of vancomycin, PYRase, and LAPase) can be used to presumptively identify the vancomycin-resistant (Van r) enterococci (Van r and PYRase and LAPase positive), leuconostocs (Van r and PYRase and LAPase negative), and pediococci (Van r , PYRase negative, and LAPase positive). The results indicate that, together with Gram stain characteristics and the catalase test, the vancomycin, LAPase, and PYRase disk tests can be used to presumptively identify Van r strains of enterococci as well as Leuconostoc and Pediococcus strains from human infections.

Fecal carriage of vancomycin-resistant enterococci in hospitalized patients and those living in the community in The Netherlands

“…A presumptive identification of Enterococcus was made on the basis of colonial morphology. Gram staining result, catalase and PYRase (Difco Laboratories, Detroit, Mich.) activities, and the presence of the Lancefield group D antigen (13). Definitive identification was done with the API 32 rapid system (Bio-Mérieux, Marcy l'Etoile, France).…”

Leuconostoc sepsis in a previously healthy neonate

“…The optimum temperature for development is between 20 • C and 30 • C, and pH between 4.4 and 5. On the surface of agar it is alpha-hemolytic or nonhemolytic, and can be confused with Streptococcus viridans, Enterococcus, or Lactococcus spp [26][27][28]. In our case the identification of the organism was made according to the following characteristics (API 20 Strep Bio Merieux, Inc. system): gram-positive coccus, catalase negative, pyrrolidonyl arylamidase (PYR) and leucinoaminopeptidasa (LAP) negative, resistance to vancomycin (Kirby Bauer method).…”

Aerococcus urinae: polyphasic characterization of the species

“…A. urinae strains have easily been separated from other catalase‐negative, Gram‐positive cocci dividing on two planes by differences in tests that are considered important within this group of bacteria. For routine laboratory identification, LAP, PYR, and vancomycin sensitivity tests have been found especially useful (33, 34) (Table 2). The finding by electron microscopy of asymmetrical cell division planes in about 30% of all A. urinae could indicate a change in the normal binary fission process.…”