Genetic relationships deduced from emm and multilocus sequence typing of invasive Streptococcus dysgalactiae subsp. equisimilis and S. canis recovered from isolates collected in the United States.

Beta-hemolytic group C and G streptococci cause a considerable invasive disease burden and sometimes cause disease outbreaks. Little is known about the critical epidemiologic parameter of genetic relatedness between isolates. We determined the emm types of 334 Streptococcus dysgalactiae subsp. equisimilis isolates, and attempted emm typing of 5 Streptococcus canis isolates from a recent population-based surveillance for invasive isolates. Thirty-four emm types were observed, including one from S. canis. We formulated multilocus sequence typing (MLST) primers with six of the seven loci corresponding to the Streptococcus pyogenes MLST scheme. We performed MLST with 65 of the 334 surveillance isolates (61 S. dysgalactiae subsp. equisimilis isolates, 4 S. canis isolates) to represent each emm type identified, including 2 to 3 isolates for each of the 25 redundantly represented emm types. Forty-one MLST sequence types (STs) were observed. Isolates within 16 redundantly represented S. dysgalactiae subsp. equisimilis emm types shared identical or nearly identical STs, demonstrating concordance between the emm type and genetic relatedness. However, seven STs were each represented by two to four different emm types, and 7 of the 10 S. dysgalactiae subsp. equisimilis eBURST groups represented up to six different emm types. Thus, S. dysgalactiae subsp. equisimilis isolates were similar to S. pyogenes isolates, in that strains of the same emm type were often highly related, but they differed from S. pyogenes, in that S. dysgalactiae subsp. equisimilis strains with identical or closely similar STs often exhibited multiple unrelated emm types. The phylogenetic relationships between S. dysgalactiae subsp. equisimilis and S. pyogenes alleles revealed a history of interspecies recombination, with either species often serving as genetic donors. The four S. canis isolates shared highly homologous alleles but were unrelated clones without evidence of past recombination with S. dysgalactiae subsp. equisimilis or S. pyogenes.

Population-based study of invasive disease due to beta-hemolytic streptococci of groups other than A and B.

BACKGROUND: Beta-hemolytic streptococci of groups other than A and B (NABS) are increasingly recognized as causes of clinically significant disease, but precise information about this heterogeneous group is lacking. We report the incidence of NABS infection and describe the epidemiologic and clinical characteristics. METHODS: Active, population-based surveillance for invasive NABS was performed over a 2-year period in the 8-county metropolitan Atlanta, Georgia, area and the 3-county San Francisco Bay, California, area. Clinical records were reviewed, and available isolates were sent to the Centers for Disease Control and Prevention (Atlanta) for additional microbiologic characterization. Incidences were calculated using year-appropriate US Census Bureau data. RESULTS: A total of 489 cases of invasive NABS infection were identified (3.2 cases per 100,000 population). The median age of patients was 55 years; 64% of patients were males, and 87% had underlying diseases. The incidence was higher among black persons than white persons (4.0 vs. 2.5 cases per 100,000 population; P < .01) and increased with age among all races. Infections were community acquired in 416 cases (85%). Among the 450 patients (94%) with NABS infection who were hospitalized, 55 (12%) died. Of 266 isolates (54%) speciated at the Centers for Disease Control and Prevention, 212 (80%) were Streptococcus dysgalactiae subspecies equisimilis; 46 (17%) were members of the Streptococcus anginosus group. S. dysgalactiae subspecies equisimilis primarily presented as skin and soft-tissue infection in older patients, whereas individuals with invasive S. anginosus group infections were more likely to be younger patients with intra-abdominal infections. CONCLUSIONS: NABS comprise multiple distinct species that cause a significant number of community-acquired invasive infections. Clinical manifestations differ by species. Thus, speciation of invasive NABS may be warranted in clinical settings.

Streptococcus ictaluri arthritis, osteolysis, myositis, and spinal meningitis in channel catfish broodstock.

This report details findings of an investigation into complaints by commercial fingerling producers of low-grade mortalities, poor reproductive success, emaciation, skin lesions, and severely arched backs among broodstock of channel catfish Ictalurus punctatus. Gross lesions involved the jaw, fin bases, and vertebral column. Jaw and fin lesions consisted of small hemorrhagic ulcers and exudate-filled tracts that communicated with underlying joints and destroyed their articular surfaces. Spinal changes, recognized grossly by severe arching of the proximal vertebral column, resulted from the collapse and displacement of vertebral bodies, causing compression of the spinal cord. Affected vertebrae were lysed by pyogranulomatous inflammation that infiltrated into adjacent muscle and the spinal canal. A Streptococcus-like organism was visualized in exudate and isolated repeatedly from lesions, but only once from the kidney of a single fish. Preliminary analysis of a 16S ribosomal DNA sequence showed a close relationship to S. iniae, S. parauberis, and S. canis. Koch's postulates were fulfilled after challenge with and reisolation of the agent from identical lesions that appeared at fin bases at 2 weeks postinjection. Historical evidence and gross and microscopic findings imply the presence of a pathogen of low virulence that is capable of producing severe localized infections after a brief period of septicemia. The disease presents as a chronic debilitating syndrome that is sufficient to inhibit mobility, feeding, and reproductive activity in affected fish. Complete biochemical and molecular characterization of the bacterium (published elsewhere) has established the agent as a novel species, S. ictaluri.

A polysaccharide of Alloiococcus otitidis, a new pathogen of otitis media: chemical structure and synthesis of a neoglycoconjugate thereof.

Alloiococcus otitidis is a recently discovered Gram-positive bacterium that has been linked with otitis media (middle ear infections). In this study, we describe the structure of a novel capsular polysaccharide (PS) expressed by the type-strain of A. otitidis, ATCC 51267, and the synthesis of a glycoconjugate composed of the capsule PS and bovine serum albumin (BSA). The capsule PS of A. otitidis type-strain was determined to be a repeating trisaccharide composed of 3-substituted N-acetyl-D-glucosamine (GlcpNAc), 6-substituted N-acetyl-D-galactosamine (GalpNAc), and 4-substituted D-glucuronic acid (GlcpA), of which the majority was amidically decorated with L-glutamic acid (Glu): {-->6)-beta-GalpNAc-(1-->4)-[Glup-->6]-beta-GlcpA-(1-->3)-beta-GlcpNAc-(1}n. Monomeric analysis performed on other A. otitidis strains revealed that similar components were variably expressed, but Glu appeared to be a regular constituent in all the strains examined. Due to the suitable presence of GlcpA and Glu, our approach for glycoconjugate synthesis employed a carbodiimide-based strategy with activation of available carboxyl groups by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), which afforded direct coupling between the capsule PS and BSA. Analysis by mass spectrometry indicated that this A. otitidis capsule PS-BSA conjugate was composed of BSA units that carried up to seven capsule PSs. This work represents the first report in the literature describing an A. otitidis cell-surface carbohydrate and the synthesis of a glycoconjugate preparation thereof. Presently, we are formulating plans to immunologically evaluate this A. otitidis glycoconjugate vaccine in animals.

Streptococcus ictaluri sp. nov., isolated from Channel Catfish Ictalurus punctatus broodstock.

A streptococcal-like organism was associated with diseased Channel Catfish Ictalurus punctatus broodstock on four commercial aquaculture operations in the Mississippi Delta. Conventional biochemical testing, 16S rRNA gene sequence analysis and DNA-DNA hybridization distinguished the isolates from these fish from previously published Streptococcus species. Comparative 16S rRNA gene sequencing studies revealed that the isolates were phylogenetically most similar to Streptococcus iniae, Streptococcus uberis and Streptococcus parauberis with divergence ranging from 2.0 to 2.3 %. Streptococcus pyogenes, Streptococcus urinalis, Streptococcus dysgalactiae subsp. dysgalactiae and Streptococcus canis were included in the analysis and showed even greater differences (2.5-3.2 % divergence). DNA relatedness was 22 % or less to the most phylogenetically related species at the optimal temperature. These data suggest that the isolates represent a novel species of Streptococcus for which the name Streptococcus ictaluri sp. nov. is proposed. The type strain is 707-05(T) (=SO2-1108(T)=ATCC BAA-1300(T)=CCUG 52536(T)).

Enterococcus caccae sp. nov., isolated from human stools.

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)).

Vagococcus carniphilus sp. nov., isolated from ground beef.

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.