Biomedical subjects
Publications and source records attributed to Arnold G Steigerwalt.
Burkholderia thailandensis is closely related to Burkholderia pseudomallei, the causative agent of melioidosis. It is generally considered avirulent and previously has been reported to occur only in Southeast Asia. We report the first case of pneumonia and septicemia caused by B. thailandensis in the United States.
Isolates of Leptospira from two human cases of leptospirosis in Denmark and France were studied using DNA-DNA relatedness, G + C content, 16S rRNA gene sequence data and pulsed-field gel electrophoresis. These isolates differed from previously described species of Leptospira and are defined as Leptospira broomii sp. nov. The type strain is 5399T (= ATCC BAA-1107T = KIT 5399T).
Taxonomic studies were performed on 13 clinical isolates (ten of which were epidemiologically related) that had been previously identified as Oerskovia turbata. Comparative phylogenetic analysis, based on 16S rRNA gene sequences, indicated that the isolates are closely related to Cellulosimicrobium cellulans with sequence similarity values ranging from 99.5 to 99.8 %. Chemotaxonomic results (fatty acid profiles and menaquinones) supported the inclusion of these isolates in the genus Cellulosimicrobium. The DNA G+C content was 74.5 mol%. The results of DNA-DNA reassociation, whole-cell sugars (with galactose as the characteristic whole sugar) and phenotypic properties, including antimicrobial resistance, indicated that these isolates are representatives of a novel species of the genus Cellulosimicrobium. The name Cellulosimicrobium funkei sp. nov. is proposed for the novel strains, with strain W6122T (=ATCC BAA-886T = DSM 16025T = CCUG 50705T) as the type strain. The definition of this novel Cellulosimicrobium species will assist in the understanding of the epidemiology and clinical significance of these micro-organisms.
C6786, the clinical isolate of the 'Oklahoma' strain of Pseudomonas (now Burkholderia) pseudomallei, was originally isolated in 1973 from a wound infection resulting from a farming accident in Oklahoma, USA. Environmental isolates C7532 and C7533 from the Oklahoma accident site were found to match C6786. These three isolates and a clinical isolate originally identified as B. pseudomallei that was recovered from a person in Georgia, USA, involved in an automobile accident were characterized by biochemical, 16S rRNA gene sequencing, multilocus sequence typing and DNA-DNA hybridization analyses. Results indicated that these strains comprise a novel species. The name Burkholderia oklahomensis sp. nov. is proposed, with strain C6786(T) (=LMG 23618(T)=NCTC 13387(T)=CCUG 51349(T)) as the type strain.
The National Antimicrobial Resistance Monitoring System Laboratory at the Centers for Disease Control and Prevention (CDC) isolated two enterococcus-like strains that were referred to the CDC Streptococcus Laboratory for further identification. The isolates were recovered from human stool samples collected on different occasions from the same individual in Portland (OR, USA) in July 2000. Conventional physiological tests distinguished these strains from all known species of enterococci. Analyses of whole-cell-protein electrophoretic profiles showed the same unique profile for the two isolates, being most similar those of Enterococcus moraviensis and Enterococcus haemoperoxidus albeit not close enough to allow conclusive inclusion in any enterococcal species. Both isolates gave positive results in tests using the AccuProbe Enterococcus genetic probe, and Lancefield extracts reacted with CDC group D antiserum. Comparative 16S rRNA gene sequencing studies also revealed that these strains were closely related to the species E. moraviensis (99.6 % identity). The results of DNA-DNA relatedness experiments confirmed that these strains represented a single novel taxon. The highest level of DNA-DNA relatedness found between the novel taxon and any of the currently recognized species of Enterococcus was 32 %, for both E. moraviensis and E. haemoperoxidus. On the basis of this evidence, it is proposed that these stool isolates constitute a novel species, for which the name Enterococcus caccae sp. nov. is proposed. The type strain is 2215-02(T) (=SS-1777(T)=ATCC BAA-1240(T)=CCUG 51564(T)).
The relatedness of Roseomonas fauriae and Azospirillum brasilense was investigated using phenotypic methods and DNA-DNA hybridization. Conventional biochemical tests did not differentiate between the two taxa. DNA-DNA hybridization experiments revealed high values for relatedness between the type strains of these species and suggest that these two taxa constitute a single species. Strains previously identified as R. fauriae should be reclassified as A. brasilense, with the name Roseomonas fauriae as a later heterotypic synonym of Azospirillum brasilense.
The genus Leptospira is classified into 13 named species and 4 genomospecies based upon DNA-DNA reassociation studies. Phenotypic tests are unable to distinguish between species of Leptospira, and there is a need for a simplified molecular approach to the identification of leptospires. 16S rRNA gene sequences are potentially useful for species identification of Leptospira, but there are a large number of sequences of various lengths and quality in the public databases. 16S rRNA gene sequences of near full length and bidirectional high redundancy were determined for all type strains of the species of the Leptospiraceae. Three clades were identified within the genus Leptospira, composed of pathogenic species, nonpathogenic species, and another clade of undetermined pathogenicity with intermediate 16S rRNA gene sequence relatedness. All type strains could be identified by 16S rRNA gene sequences, but within both pathogenic and nonpathogenic clades as few as two or three base pairs separated some species. Sequences within the nonpathogenic clade were more similar, and in most cases < or =10 bp distinguished these species. These sequences provide a reference standard for identification of Leptospira species and confirm previously established relationships within the genus. 16S rRNA gene sequencing is a powerful method for identification in the clinical laboratory and offers a simplified approach to the identification of Leptospira species.
We report the first case of endocarditis caused by Gordonia polyisoprenivorans and concisely review the English literature regarding bloodstream infections caused by Gordonia species.
Four strains of novel, rapidly growing, acid-alcohol-fast-staining bacteria were characterized with a polyphasic approach. Isolates were received by the Centers for Disease Control and Prevention from domestic health department laboratories for reference testing as unidentifiable, clinical mycobacteria. Bacteria were rod-shaped and produced non-pigmented (white to beige), non-photochromogenic, smooth or wrinkled-rough colonies on Middlebrook 7H10 and 7H11 media at 33 degrees C. The smooth and wrinkled colony forms were representative of two species with 68.0 and 72.0 mol% DNA G+C content. The cell wall contained meso-diaminopimelic acid and mycolic acids. Species were characterized by cellular fatty acids of C10:0, C14:0, C16:1omega9t, C16:0, C18:1omega9c and 10-methyl C18:0 (tuberculostearic acid). HPLC analysis of mycolic acids produced a novel late-emerging, genus-specific mycolate pattern. TLC analysis demonstrated a novel alpha(+)-mycolate. Species were 98.9% similar by comparison of 16S rRNA gene sequences; however, the DNA-DNA association was <28 %. Phylogenetic analysis of 16S rRNA gene sequences demonstrated an association with Rhodococcus equi, although a DNA-DNA relatedness value of 2% did not support a close relationship. PCR analysis of a proposed, selected actinomycete-specific 439 bp fragment of the 65 kDa heat-shock protein was negative for three of the four isolates. The creation of Segniliparaceae fam. nov. is proposed to encompass the genus Segniliparus gen. nov., including two novel species, the type species Segniliparus rotundus sp. nov. and Segniliparus rugosus sp. nov., with the respective type strains CDC 1076(T) (=ATCC BAA-972(T)=CIP 108378(T)) and CDC 945(T) (=ATCC BAA-974(T)=CIP 108380(T)).
Definitive diagnosis of leptospirosis has traditionally depended upon the isolation of leptospires from clinical specimens or the demonstration of seroconversion in paired acute and convalescent serum samples. Both of these approaches require expertise not routinely available in clinical laboratories and usually result in delayed diagnosis. Conventional PCR assays have been developed, but all have limitations which have restricted their widespread use. In order to overcome these limitations, a real-time PCR assay was developed using a 423 bp target on the lipL32 gene, which is conserved among pathogenic serovars of LEPTOSPIRA: Reactions were monitored by SYBR green fluorescence and melting curve analysis. Representative serovars from 16 species of Leptospira and over 40 species of other bacteria and fungi were tested. Positive results were obtained with all pathogenic leptospiral serovars, with the exception of Leptospira fainei serovar Hurstbridge. The analytical sensitivity of this assay was 3 genome equivalents per reaction; approximately 10 genome equivalents were detectable in human urine. Leptospiral DNA was amplified from blood containing EDTA or citrate anticoagulants, but heparin, sodium polyanetholesulfonate and saponin were inhibitory. The assay successfully detected leptospiral DNA from serum and urine samples of patients with leptospirosis. This assay has the potential to facilitate rapid, sensitive diagnosis of acute leptospirosis.
Mycobacterium peregrinum consists of two taxa: types I and II. We evaluated 43 clinical type II strains from throughout the United States. They were responsible for soft-tissue and bone infections, catheter-related infections, and possible pneumonitis. By carbohydrate utilization, they were indistinguishable from type I strains, being D-mannitol and trehalose positive. However, they had a distinct susceptibility pattern that included intermediate ciprofloxacin MICs but low clarithromycin and doxycycline MICs of < or =1 microg/ml. These features were also shared by reference isolates of Mycobacterium senegalense from African bovine cases of "farcy." By 16S rRNA gene sequencing, the type II isolates shared 100% sequence identity with M. senegalense. Partial sequencing of the type II hsp65 gene (441 bp) revealed four sequevars showing > or =98.4% identity with each other and > or =98.6% identity with the sequence of five bovine strains of M. senegalense. There was < or =97.1% identity with M. peregrinum type I isolates and other Mycobacterium fortuitum group species. Sequencing of additional gene targets including the 16S-23S rDNA internal transcribed spacer region and the rpoB gene (partial sequence) revealed a similar phylogenetic grouping. DNA-DNA hybridization showed 76 to 99% relatedness between the bovine and human strains. These studies demonstrate that type II isolates are not isolates of M. peregrinum but represent human strains of M. senegalense. This study is the first to demonstrate this species as a human pathogen. Representative human M. senegalense strains include ATCC 35755 and newly submitted strains ATCC BAA-849, ATCC BAA-850, and ATCC BAA-851.
CDC coryneform group A-3 bacteria are rare human pathogens. In this study, six group A-3 isolates (two from blood, one from cerebrospinal fluid, and one each from homograft valve, lip wound, and pilonidal cyst) were compared to the type strains of phenotypically related organisms, Cellulomonas fimi, Cellulomonas hominis, Oerskovia turbata, and Sanguibacter suarezii, and characterized by phenotypic, chemotaxonomic, and genotypic studies. DNA-DNA reassociation analysis identified two genomic groups, and phylogenetic analysis of the 16S rRNA gene sequence identified the taxonomic positions of these groups to genus level. Two groups were defined, and both were more closely related to Cellulomonas species: one group of three strains, for which we propose the new species Cellulomonas denverensis sp. nov., with the type strain W6929 (ATCC BAA-788(T) or DSM 15764(T)), was related to C. hominis ATCC 51964(T) (98.5% 16S rRNA gene sequence similarity), and the second group of three strains was related to C. hominis ATCC 51964(T) (99.8 to 99.9% 16S rRNA gene sequence similarity). The definition of this new Cellulomonas species and the confirmation of three strains as C. hominis serve to further clarify the complex taxonomy of CDC coryneform group A-3 bacteria and will assist in our understanding of the epidemiology and clinical significance of these microorganisms.
The Mycobacterium fortuitum third biovariant complex (sorbitol-negative and sorbitol-positive) contains unnamed taxa first characterized in 1991. These organisms can cause respiratory infections, a spectrum of soft tissue and skeletal infections, bacteraemia and disseminated disease. To evaluate this group of organisms, clinical reference isolates and the type strains of M. fortuitum third biovariant complex sorbitol-negative (n = 21), M. fortuitum third biovariant complex sorbitol-positive (n = 3), M. fortuitum (n = 3), Mycobacterium peregrinum (pipemidic acid-susceptible) (n = 1), Mycobacterium porcinum (n = 1), Mycobacterium senegalense (n = 2) and Mycobacterium septicum (n = 1) were characterized by using conventional phenotypic (morphological, physiological and antimicrobial susceptibilities), chemotaxonomic (HPLC and cellular fatty acids) and genotypic [RFLP of the rRNA gene (ribotyping), PCR-RFLP of a 439 bp segment of the 65 kDa hsp gene (PCR restriction analysis) and 16S rRNA gene sequence] analysis, DNA G + C content and DNA-DNA relatedness analyses. The results of these studies indicated that the strains comprised M. porcinum (n = 13), M. septicum (n = 1) and four novel closely related genetic groups within the M. fortuitum third biovariant complex: Mycobacterium boenickei sp. nov. (n = 6), Mycobacterium houstonense sp. nov. (n = 2), Mycobacterium neworleansense sp. nov. (n = 1) and Mycobacterium brisbanense sp. nov. (n = 1), with type strains ATCC 49935T (= W5998T = DSM 44677T), ATCC 49403T (= W5198T = DSM 44676T) ATCC 49404T (= W6705T = DSM 44679T) and ATCC 49938T (= W6743T = DSM 44680T), respectively.
The taxonomic relationships of two actinomycetes provisionally assigned to the genus Rhodococcus were determined using a polyphasic taxonomic approach. The generic assignment was confirmed by 16S rRNA gene similarity data, as the organisms, strains MTCC 1534 and W 4937(T), were shown to belong to the Rhodococcus rhodochrous subclade. These organisms had phenotypic properties typical of rhodococci; they were aerobic, Gram-positive, weakly acid-fast actinomycetes that showed an elementary branching-rod-coccus growth cycle and contained meso-diaminopimelic acid, arabinose and galactose in whole-organism hydrolysates, N-glycolated muramic acid residues, dehydrogenated menaquinones with eight isoprene units as the predominant isoprenologue and mycolic acids that co-migrated with those extracted from the type strain of R. rhodochrous. The strains had identical phenotypic profiles and belong to the same genomic species, albeit one distinguished from Rhodococcus pyridinivorans, with which they formed a distinct phyletic line. They were also distinguished from representatives of all of the species classified in the R. rhodochrous 16S rRNA gene tree using a set of phenotypic features. The genotypic and phenotypic data show that the strains merit recognition as a novel species of Rhodococcus. The name proposed is Rhodococcus gordoniae sp. nov., with the type strain W 4937(T) (=DSM 44689(T)=NCTC 13296(T)).
Nine enterococcus-like strains were referred to the Streptococcus Laboratory at the Centers for Disease Control and Prevention (CDC) for further identification from the National Antimicrobial Resistance Monitoring System Laboratory at the CDC. The cultures were isolated from ground beef purchased from retail in Oregon in 2000. Conventional biochemical testing and analysis of whole-cell protein electrophoretic profiles distinguished these strains from known species of enterococci and vagococci. Comparative 16S rRNA gene sequencing studies revealed that these strains were most closely related to the species Vagococcus fluvialis. DNA-DNA reassociation studies confirmed that these nine strains represented a new taxon. The relative binding ratio was 87 % or greater at the optimal temperature, and the divergence was less than 1 % for strains hybridized against the isolate designated the type strain. DNA-DNA relatedness was 25 % to V. fluvialis and 9 % or less to the other three species of Vagococcus. DNA-DNA relatedness was 33 % or less to the 25 currently described species of Enterococcus. On the basis of this evidence, it is proposed that these strains be classified as Vagococcus carniphilus sp. nov. The type strain of V. carniphilus is 1843-02T (= ATCC BAA-640T = CCUG 46823T). The clinical significance (if any) of these strains is yet to be determined.
Phenotypic and phylogenetic studies were performed on four Campylobacter-like organisms recovered from three seals and a porpoise. Comparative 16S rRNA gene sequencing studies demonstrated that the organisms represent a hitherto unknown subline within the genus Campylobacter, associated with a subcluster containing Campylobacter jejuni, Campylobacter coli and Campylobacter lari. DNA-DNA hybridization studies confirmed that the bacteria belonged to a single species, for which the name Campylobacter insulaenigrae sp. nov. is proposed. The type strain of Campylobacter insulaenigrae sp. nov. is NCTC 12927(T) (=CCUG 48653(T)).
We have identified an unusual group of viridans group streptococci that resemble Streptococcus pneumoniae. DNA-DNA homology studies suggested that a subset of these isolates represent a novel species that may be included in the S. oralis-S. mitis group of viridans group streptococci. We suggest that this novel species be termed Streptococcus pseudopneumoniae. A combination of phenotypic and genetic reactions allows its identification. S. pseudopneumoniae strains do not have pneumococcal capsules, are resistant to optochin (inhibition zones, less than 14 mm) when they are incubated under an atmosphere of increased CO2 but are susceptible to optochin (inhibition zones, >14 mm) when they are incubated in ambient atmospheres, are not soluble in bile, and are positive by the GenProbe AccuProbe Pneumococcus test. The bile solubility test is more specific than the optochin test for identification of S. pneumoniae. Genetic tests for pneumolysin (ply) and manganese-dependent superoxide dismutase (sodA) and identification tests with a commercial probe, AccuProbe Pneumococcus, do not discriminate between the new species and S. pneumoniae.
Molecular methodologies have become useful techniques for the identification of pathogenic Nocardia species and for the recognition of novel species that are capable of causing human disease. Two isolates recovered from immunocompromised patients were characterized as Nocardia nova by biochemical and susceptibility testing results. The restriction fragment length polymorphism (RFLP) patterns obtained by restriction endonuclease analysis (REA) of an amplified portion of the heat shock protein gene were identical to those obtained with the type strain of N. nova. REA of an amplified portion of the 16S rRNA gene showed RFLP patterns that were unlike those obtained for the type strain of N. nova but that were similar to those obtained for the type strains of N. africana and N. veterana. Subsequent sequencing of a portion of the 16S rRNA gene produced identical results for the two patient isolates. Sequence analysis of 1,352-bp portions of the 16S rRNA gene indicated that these isolates were 99.8% similar to the recently described species N. veterana but were only 99.3, 98.1, and 98.1% similar to the type strains of N. africana, N. nova, and N. vaccinii, respectively. DNA-DNA hybridization studies confirmed that the two patient isolates belonged to the same species but were not closely related to N. africana, N. nova, N. vaccinii, or N. veterana. The patient isolates have been designated N. kruczakiae sp. nov. Because N. africana, N. veterana, and the new species are not readily differentiated from N. nova by phenotypic methods alone, the designation "N. nova complex" can be used to designate isolates such as these that phenotypically resemble N. nova but that have not been definitively characterized by 16S rRNA gene sequencing or DNA-DNA hybridization.