Matrix-assisted laser desorption ionization-time of flight mass spectrometry has emerged as a rapid, cost-effective alternative for bacterial species identification. Identifying 60 blind-coded nonfermenting bacteria samples, this international study (using eight laboratories) achieved 98.75% interlaboratory reproducibility. Only 6 of the 480 samples were misidentified due to interchanges (4 samples) or contamination (1 sample) or not identified because of insufficient signal intensity (1 sample).Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a fast and costeffective alternative for bacterial species identification in microbiology. On the basis of mass analysis of the protein composition of a bacterial cell, which is assumed to be characteristic for each bacterial species, it is possible to determine the species within few minutes, starting from whole cells, cell lysates, or crude bacterial extracts (2, 3, 5, 6). The proof of principle of MALDI-TOF MS for bacterial species identification was shown a decade ago (2, 5, 6); however, due to low reproducibility, it has not been widely adopted in clinical microbiology. We have recently shown that use of a larger mass range for detection (2,000 to 20,000 Da), dedicated analysis software for spectral pattern matching, and a highquality reference database of spectra generated from qualitycontrolled culture collection strains resulted in accurate species identifications, with high intralaboratory reproducibility (7). For interlaboratory reproducibility, there are only very limited data available (8, 10). We therefore evaluated the interlaboratory reproducibility for MALDI-TOF MS-based species identification in a multicenter study, applying the above-described MALDI-TOF MS improvements.(

Fourteen isolates of two different bacterial species isolated from the surface of smear-ripened cheeses were found to exhibit many characteristics of the genus Arthrobacter. The isolates were aerobic, Gram-positive, catalase-positive, non-spore-forming and non-motile. The cell-wall peptidoglycan contained lysine, alanine and glutamic acid. rrs sequence analysis indicated that the new isolates Re117T and Ca106T are closely related to the Arthrobacter nicotianae group and showed highest sequence similarity (>98 %) to Arthrobacter nicotianae and Arthrobacter protophormiae. However, DNA–DNA hybridization studies indicated that the strains represented two novel genomic species within the genus Arthrobacter and did not belong to A. nicotianae or A. protophormiae (<43 % DNA–DNA relatedness). On the basis of the phylogenetic and phenotypic distinctiveness of the new isolates, these bacteria should be classified as two novel Arthrobacter species, for which the names Arthrobacter bergerei sp. nov. and Arthrobacter arilaitensis sp. nov. are proposed. Type strains have been deposited in culture collections as Arthrobacter bergerei Ca106T (=CIP 108036T=DSM 16367T) and Arthrobacter arilaitensis Re117T (=CIP 108037T=DSM 16368T).

A new Corynebacterium species, Corynebacteriurn argentoratense was isolated from the throats of four human patients. It is characterized by the presence of chemotype IV, a cell wall, corynomycolic acids, and a G+C content ranging from 60 to 61 mol%. Strains belonging to this species exhibit high levels of DNA relatedness as determined by DNA-DNA hybridization experiments (S1 nuclease procedure) but no close DNA relatedness with related Corynebacterium species. Phylogenies based on comparative analyses of nearly complete smallsubunit rDNA sequences confirmed the inclusion of this new species within the genus Corynebacteriurn and grouped it in a cluster with C. diphtheriae, C. ulcerans, C. pseudotubercubsis, and C. kutscheri. PCR experiments revealed an absence of the gene coding for diphtheria toxin. This new species can be identified by its mycolic acid pattern, fermentation of sugars, and enzymatic activities. Strain IBS B10697 (CIP 104296) is the type strain of C. argentorateme.

Diphtheria is a disease with a long history that almost completely disappeared from developed countries. In addition, until 1987, systemic infections involving Corynebacterium diphtheriae were rare. However, in 1990, an epidemic occurred in Russia. These two circumstances have provided the stimulus to gain insight into the situation in France. In fact, between 1987 and 1993, a total of 59 C. diphtheriae strains were isolated. Epidemiological data were collected for patients from whom 40 strains were isolated from normally sterile sites, including 34 from blood cultures, and half of the bacteremic patients developed endocarditis. Osteoarticular involvement was noted in 11 of these 40 patients, including 5 bacteremic patients. The fatality rate following bacteremia was 36%, despite specific antibiotic treatment (beta-lactams and aminoglycosides). The mean age of the participants was 38 years, with half of the patients subsisting under low socioeconomic conditions and suffering from homelessness or alcoholism. Apparently, the skin turned out to be the major route of transmission in this reemerging disease. Eighty-eight percent of the isolates belonged to the C. diphtheriae biotype mitis. These were found predominantly in the Paris area, and most were of the same ribotype. Those isolates originating from the overseas territories (Guyana and New Caledonia) belonged to C. diphtheriae biotype gravis. No strains were positive for the tox gene by PCR. This study attests to the persistent circulation in France of C. diphtheriae in the form of systemic infections. The matter is especially significant since these strains are nontoxigenic and are of a unique ribotype. The strains are, however, sensitive to most antibiotics, although 20% are rifampin resistant.

We analyzed 62 clinical isolates of streptogramin A-resistant (SGA r ) Staphylococcus aureus collected between 1981 and 2001 in 14 hospitals located in seven French cities. These isolates, including five with decreased susceptibility to glycopeptides, were distributed into 45 antibiotypes and 38 SmaI genotypes. Each of these genotypes included between 1 and 11 isolates, the SmaI patterns of which differed by no more than three bands. Although numerous clones were identified, we observed the spread of monoclonal isolates either within the same hospital or within hospitals in distinct cities and at large time intervals. Hybridization with probes directed against 10 SGA r genes (vatA, vatB, vatC, vatD, vatE, vgaA, vgaB, vgaAv, vgbA, and vgbB) revealed six patterns: vgaAv (21 isolates), vatA-vgbA (24 isolates), vgaAv-vatB-vgaB (14 isolates), vgaAv-vatA-vgbA (1 isolate), vgaAv-vatA-vgbA-vatB-vgaB (1 isolate), and vgaA (1 isolate). We detected at least one SGA r determinant in all of the tested isolates. vgaAv, which is part of the recently characterized transposon Tn5406, was found in 59.7% of the tested isolates. Of the 16 streptogramin B-susceptible isolates, 14 carried vgaAv alone and were susceptible to the mixtures of streptogramins, whereas the 2 isolates carrying vgaAv-vatB-vgaB were resistant to these mixtures. vatA-vgbA was found on plasmids of the same apparent size in 26 (42%) of the tested clinical isolates from 18 unrelated SmaI genotypes. The possible dissemination of some of the multiple clones characterized in the present study with an expected increased selective pressure of streptogramins following the recent licensing of Synercid (quinupristin-dalfopristin) must be carefully monitored.Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen worldwide. Glycopeptides have been the reference drugs for the treatment of MRSA infections (16,21,30). After the emergence of clones with decreased susceptibility to these antibiotics, first reported as sporadic cases in several countries and more recently also as outbreaks, alternative treatments such as quinupristin-dalfopristin (Synercid) have been promoted (17,21,33). Quinupristin and dalfopristin are derivatives of pristinamycins IA and IIA, respectively (10). Quinupristin-dalfopristin is an injectable, semisynthetic, mixture with a synergistic activity against most gram-positive pathogens. Since 1999, quinupristin-dalfopristin has been available for use in hospitals for the treatment of infections caused by gram-positive cocci that are resistant to other antibiotics.Quinupristin-dalfopristin and the natural antibiotics produced by streptomycetes, such as streptogramin, pristinamycin, synergistin, mikamycin, and virginiamycin, are mixtures of two classes of compounds, A and B, with distinct primary structures (10, 14). The A compounds are polyunsaturated cyclic macrolactones, and the B compounds are cyclic hexadepsipeptides. Both types of compounds bind different targets in the peptidyltransferase domain of the 23S ribosoma...