The taxonomic position of an actinomycete, strain 1BDZ^T, isolated from a clinical human source was determined using a polyphasic approach. Phylogenetic analysis based on almost complete 16S rDNA sequences showed that this organism consistently formed a distinct line with theAmycolatopsis methanolicasubclade within the genusAmycolatopsis, and shared moderately low 16S rDNA similarity (<96·5 %) with other species. The organism was also found to have chemical and morphological properties typical of members of the genusAmycolatopsis. A range of phenotypic characteristics readily distinguished this strain from representatives of all species ofAmycolatopsiswith validly published names. On the basis of these data, a novel species,Amycolatopsis palatopharyngissp. nov., is proposed to accommodate strain 1BDZ^T(=AS 4.1729^T=PCM 2600^T).

Nucleoid-associated proteins (NAPs) are the most abundant proteins involved in bacterial chromosome organization and global transcription regulation. The mycobacterial NAP family includes many diverse proteins; some are unique to actinobacteria, and many are crucial for survival under stress (e.g., HupB and Lsr2) and/or optimal growth conditions (e.g., mycobacterial integration host factor [mIHF]).

Propionibacterium propionicum belongs to the “acnes group” of propionibacteria, which is currently considered as clinically important because of its growing potential in infections, in particular with those connected with immune system dysfunctions. Propionibacteria are thought to be actinomycete-like microorganisms and may still cause diagnostic difficulties. The chloroform-methanol extracts of the cell mass ofP. propionicum (type strain) gave in TLC analysis the characteristic glycolipid profile containing four major glycolipids, labeled G₁ through G₄. These polar lipids were found to be useful chemotaxonomic markers to differentiate P. propionicum from other cutaneous propionibacteria, in particular from strains of the acnes group. Glycolipids G₁–G₄ were isolated and purified using gel-permeation chromatography, TLC, and high performance liquid chromatography, and their structures were elucidated by compositional and methylation analyses, specific chemical degradations, MALDI-TOF mass spectrometry, and ¹H NMR and ¹³C NMR spectroscopy, including HMBC, TOCSY, HMQC, and NOESY experiments. Glycolipids G₂ and G₃ possess as backbone α-d-Glcp-(1 → 3)-α-d-Glcp-(1 → 1)-Gro (Gro, glycerol), in which position O-2 of the glycerol residue is acylated by a fatty acid (mainly C₁₅:0) while O-3 is substituted by an alkyl ether chain. In glycolipid G₃, an additional fatty acyl chain was linked to O-6 of the terminal glucose residue. Glycolipid G₄ was structurally related to G₂ but devoid of one glucose residue. Glycolipid G₁ was isolated in small amounts, and its structure was therefore deduced from MALDI-TOF-MS experiments alone, which revealed that it possessed the structure of G₂ but was lacking one fatty acid residue. In studies on the biological properties of P. propionicum glycolipids, the anti-P. propionicumrabbit antisera reacted in dot enzyme-immunoblotting test with G₂ and G₃. Glycolipid G₃ was able to induce the delayed type of hypersensitivity. The results indicated that these novel ether linkage-containing polar glycolipids are immunogenic and possibly active in hypersensitivity, and thus, in pathogenesis.

Elizabethkingia miricola is a rare Gram-negative bacterium found in water and clinical specimens. Typical culturing methods often misidentify Elizabethkingia spp. as Flavobacterium or Chryseobacterium. Although diagnosis is based on culturing samples taken from sterile sites, such as blood, a proper identification of this bacterium requires an expertise that goes beyond the capabilities of a typical clinical laboratory. A 35-year-old woman diagnosed with common variable immunodeficiency was admitted to our center. Previous treatment with antibiotics (amoxicillin plus clavulanate, first and third generation of cephalosporins, macrolides) and systemic corticosteroids (up to 120 mg/day of prednisolone) failed to arrest the spread of inflammation. Gingival recession was observed in her oral cavity, resulting in an apparent lengthening of her teeth. In addition to typical commensal bacteria, including streptococci and neisseriae, strains of Rothia mucilaginosa and Elizabethkingia miricola were identified upon a detailed microbiological examination using a MALDI-TOF MS Biotyper system. The presence of the latter strain correlated with severe periodontitis, lack of IgA in her saliva and serum, a very low IgG concentration (< 50 mg/dl), IgM-paraproteinemia, decreases in C3a and C5a and microvascular abnormality. High-dose immunoglobulin (to maintain IgG > 500 mg/dl) and targeted levofloxacin treatment resulted in immune system reconstitution, oral healing, and eradication of the Elizabethkingia infection. E. miricola rarely causes disease in healthy individuals. However, the overgrowth of commensal bacteria, lack of IgG/IgA, microvasculopathy and complement cascade activation in patients with humoral immunodeficiency may facilitate Elizabethkingia invasion. Overuse of antibiotics, particularly beta-lactams, may cause mucosal colonization by E. miricola, followed by its multiplication combined with periodontitis that prompts bacterial translocation. MALDI-TOF Biotyper analysis may become a method of choice for identification of Elizabethkingia infections.

A Gram-positive, coccoid, non-spore-forming bacterium, designated strain 3-6^T, was isolated from farmland soil and subjected to a polyphasic taxonomic analysis. Comparative analysis of the 16S rRNA gene sequence revealed that the strain represented a novel member of the suborderMicrococcineae. Its nearest phylogenetic neighbour was the type strain ofGeorgenia muralis(94.2 % 16S rRNA gene sequence similarity). Chemotaxonomic characteristics of strain 3-6^Twere as follows: the major menaquinone was MK-8(H₄); the polar lipids consisted mainly of diphosphatidylglycerol, phosphatidylglycerol and one unknown glycolipid; the predominant fatty acids were anteiso-C_15 : 0, anteiso-C_17 : 0and iso-C_16 : 0; mycolic acids were absent. A new murein type,l-lys–gly–l-glu–l-Glu (A4α), was found in the peptidoglycan of the cell wall. The DNA G+C content was 69.8 mol%. On the basis of morphological, chemotaxonomic and phylogenetic characteristics, it is suggested that strain 3-6^Trepresents a novel species of a new genus within the suborderMicrococcineae, for which the nameRuania albidiflavagen. nov., sp. nov. is proposed. The type strain ofRuania albidiflavais 3-6^T(=CGMCC 4.3142^T=DSM 18029^T=JCM 13910^T=PCM 2644^T).