Nocardicin A, a new monocyclic beta-lactam antibiotic III. In vitro evaluation

Nocardicin A, a new monocyclic beta-lactam antibiotic, exerts a comparatively potent antimicrobial activity against gram-negative organisms, especially Pseudomonas aeruginosa, the indole-positive and indole-negative Proteus groups (except Pr. morganii), Serratia marcescens and the Neisseria groups. The in vitro antimicrobial activity of nocardicin A against clinical isolates of Ps. aeruginosa was about twice that of carbenicillin. The mean MICs of nocardicin A for Pr. mirabilis, Pr. rettgeri and Pr. inconstans ranged from 3.13 to 12.5 microgram/ml and were 25 similar to 50 microgram/ml for Pr. vulgaris. Nocardicin A in concentrations of 12.5 similar to 50 microgram/ml inhibited 30 strains (48 percent) of S. marcescens usually resistant to beta-lactam antibiotics. However, nocardicin A had no significant in vitro activity against Staphylococci and Escherichia coli. No cross-resistance was seen between nocardicin A and other beta-lactam antibiotics. This antibiotic was stable to beta-lactamase. The in vitro activity of nocardicin A against Ps. aeruginosa and Pr. mirabilis was greatly influenced by the assay media used. Nocardicin A was bactericidal and appeared to act synergistically with serum bactericidal factors against Ps. aeruginosa and with polymorphonuclear leukocytes against Ps. aeruginosa, E. coli and Pr. vulgaris. The bactericidal activity of nocardicin A against the above 3 organisms, therefore, increased markedly in the presence of fresh serum and polymorphonuclear leukocytes.

Thin-layer chromatographic analysis of mycolic acid and other long-chain components in whole-organism methanolysates of coryneform and related taxa

Acid methanolysates of strains representing 58 coryneform taxa were examined for mycolic acids and other long-chain constituents by thin-layer chromatography. Mycolic esters were detected in the methanolysates of true corynebacteria but not in those from plant pathogenic bacteria, Corynebacterium haemolyticum, Corynebacterium pyogenes or from representatives of the genera Arthrobacter, Cellulomonas, Curtobacterium, Kurthia or Oerskovia. Thin-layer chromatography of whole-organism methanolysates provides a simple method for distinguishing true corynebacteria from coryneforms which do not contain mycolic acids, and from nocardiae and mycobacteria which produce mycolic acids of different mobility. At present the mycolic esters of true corynebacteria cannot be clearly separated from those of some rhodochrous strains.

Rapid method for the detection and identification of mycolic acids in aerobic actinomycetes and related bacteria

A rapid method for the identification of lipids characteristic of the genera Corynebacterium, Mycobacterium, Nocardia, and the "rhodochrous group" has been developed. Modifications of previously described methods make this procedure suitable for use in the clinical laboratory. Thin-layer chromatography is used to demonstrate the presence of the lipid characteristic of Nocardia spp. (type A) in some corynebacteria, nocardias, and members of the "rhodochrous group." Precipitation in ether and ethanol is used to demonstrate the presence of mycobacterial mycolic acids. Since this procedure can be carried out in less than 2 days and the lipids are extracted from the same batch of cells grown for diaminopimelic acid and whole-cell sugar analyses, it can readily be added to the battery of tests performed in reference laboratories that deal with aerobic actinomycetes and related bacteria.

[Characterisation of D(-)glyceric acid from Nocardia caviae (author's transl)]

A glycolipid was found in a strain of Nocardia caviae. It consists of glucose, myristic, palmitic and stearic acids and a polyhydroxylated acid. The structure of this hydroxyacid was demonstrated by the identification of the product glycerol after LiA1H4 reduction of the glycolipid methyl ester and subsequent hydrolysis, by comparison of the infrared spectra of the hydroxyacid and glyceric acid, by gas chromatography of acetylated methyl and ethyl esters of the polyhydroxylated acid and of standard glyceric acid and by mass spectrometry of the diacetylated methyl ester. The hydroxyacid from the glycolipid is D(-)glyceric acid, a compound rarely found amongst natural products.

Deoxyribonucleic acid reassociation in the classification of the 'rhodochrous' complex and allied taxa

The degree of binding was determined between DNA preparations from gordonae and rhodochrous strains and uracil-labelled DNA from five reference strains, Nocardia asteroides NK20, N. pellegrino PII, Gordona bronchialis TI, G. terrae T5 and rhodochrous strain R90. Most of the rhodochrous and pellegrino strains fell into one of two genetically homogeneous taxa. The nucleotide sequence homology data also suggested that G. bronchialis, G. rubra, and more equivocally G. terrae, formed distinct species. However, the values for DNA relatedness between these species, and between then and the rhodochrous homology groups, were comparatively low. Only a small degree of nucleotide sequence homology was found between the N. asteroides reference system and the rest of the taxa studied. The nucleotide composition of the DNA preparations from 29 of the 30 test strains fell between 63 and 69 mol% guanine plus cytosine.

Free mycolic acids as criteria in the classification of Gordona and the 'rhodochrous' complex

The methyl esters of free mycolic acids from representative strains of Gordona bronchialis, G. rubra, G. terrae and Nocardia kirovani each gave, on mass spectroscopy, homologous series of anhydromycolic esters containing from one to four double bonds with the main components of the parent mycolic acids centered on 56, 58, 62 or 64 carbon atoms (total range from C52 to C66). The mycolic acids from the Gordona strains, with chain lengths centered around C60, form a group intermediate in size between nocardomycolic acids (centered around C50) and mycolie different from those of the 'rhodochrous' complex which have anhydromycolates ranging from C34 to C50. Gordonae are thus more closely related in their mycolic acid composition to Nocardia than to Mycobacterium but can be distinguished from each of these genera.

Free mycolic acids as criteria in the classification of Nocardia and the 'rhodochrous' complex

The methyl esters of free mycolic acids from representative strains of Nocardia asteroides, N. brasiliensis, N. caviae and the 'rhodochrous' complex were subjected to detailed mass spectral analysis. The anhydromycolic esters of the Nocardia strains consisted of homologous series containing from zero to three double bonds, with the main components of the parent mycolic acids centred on C52 to C54 (range C46 to C58). The anhydromycolates from one rhodochrous strain, Nocardia opaca, had a molecular weight range similar to the nocardiae (C46 to C57) but the remaining rhodochrous strains gave an homologous series of anhydromycolates containing from zero to two double bonds, with the main components of the parent mycolic acids centred on C38, C42, C44 or C46 (total range from C34 to C50). The mycolic acids from the rhodochrous strains with chain lengths centred around C40 form a group intermediate in size between corynomycolic acids (centred around C32) and nocardomycolic acids (centred around C50). These data weaken the case for retaining the 'rhodochrous' complex in the genus Mycobacterium, and also show that many rhodochrous strains can be distinguished from true nocardiae and corynebacteria. These results confirm the value of lipid characters in the classification of these organisms.

[Distribution of pyrimidine blocks in the DNA of Brevibacterium linens, Arthrobacter globiformis, Nocardia corallina and Nocardia rubra]

The nucleotide composition and the frequency of pyrimidine blocks were studied in DNA of the following bacteria: Brevibacterium linens (Weignamm, 1910) Breed, 1953; Arthrobacter globiformis (Conn, 1928) Conn et Dimmick, 1947; Nocardia corallina (Bergey et al., 1923) Waksman et Henrici, 1948; Nocardia rubra (Krassilnikov, 1949) Waksman et Henrici, 1948. These organisms are classed by some microbiologists as mycobacteria (the Mycobacteriaceae family) while other authors regard them as representatives of three families belonging to two orders. About 60 percent of all pyrimidines in DNA of these bacteria are found in the sequences pur-pyr-pur and pur-pyr-pyr-pur, the number of dipyrimidines being higher than the amount of monopyrimidine nucleotides. The content of dipyrimidine nucleotides in DNA of Nocardia corallina and Nocardia rubra is higher (16.8 mole %) than the content of dipyrimidine blocks in DNA of Brevibacterium linens and Arthrobacter globiformis, in which the quantity of dipyrimidines is almost the same (13.9 and 14.4 mole %). A new characteristic, the selected mean value, is suggested to evaluate differences in the distribution of pyrimidines in DNA.

Ansamycin biogenesis: studies on a novel rifamycin isolated from a mutant strain of Nocardia mediterranei

A novel ansamycin, rifamycin W, was isolated from a mutant strain of Nocardia mediterranei. The metabolic origin of rifamycin W was studied by (13)C nuclear magnetic resonance spectroscopy. Examination of the proton-decoupled pulse and Fourier transform (13)C spectra of rifamycin W biogenetically enriched with [1-(13)C]-, [2-(13)C]-, and [3-(13)C]propionate and with [1-(13)C]acetate has revealed that the alignment of acetate and propionate units corresponds to that previously proposed for rifamycin S. Washed mycelium from a rifamycin B-producing strain of N. mediterranei transformed rifamycin W into rifamycin B. We suggest that rifamycin W is a normal intermediate in the biosynthesis of the other rifamycins. These results, together with the structural similarity of rifamycin W to the streptovaricins, reinforce our hypothesis that a common progenitor is involved in the biogenesis of all naphthalenic ansamycins.

Blastic transformtion of mouse spleen lymphocytes by a water-soluble mitogen extracted from Nocardia

A water-soluble extract of Nocardia markedly increased in vitro [(3)H]thymidine incorporation by mouse spleen lymphocytes. The blastogenic activity of the extract and lipopolysaccharide was studied comparatively on various mouse lymphocyte subpopulations. The data obtained by [(3)H]thymidine incorporation and by electron microscopy have demonstrated that this preparation stimulates selectively mouse bone-marrow-derived cortisone-sensitive lymphocytes. This stimulation is related neither to a natural infection of mice with Nocardia organisms nor to the presence in Nocardia water-soluble mitogen of a lipopolysaccharide contaminant or of a lipopolysaccharide-like material.

Chemical characterization of organisms isolated from leprosy patients

CHEMICAL ANALYSES OF THE CELL WALLS OF ORGANISMS ISOLATED IN VARIOUS PARTS OF THE WORLD FROM CASES OF LEPROMATOUS AND TUBERCULOID LEPROSY MAKE POSSIBLE THEIR ASSIGNMENT TO ONE OF THE THREE GENERA: Corynebacterium, Mycobacterium, or Propionibacterium. One, bacterium 22M, remains unassigned. The combined chemical and enzymatic properties attributed to leprosy bacilli freshly harvested from lepromata are found collectively, but not individually, in these three genera.

An unusual strain of Nocardia isolated from an infected cat

An unusual strain of Nocardia, designated VH/CN-71, was isolated from a pouch-like growth in the inguinal region of a young cat. Although this organism resembles Nocardia brasiliensis in a number of its physiological activities, it appears to be more closely related to a nocardioform organism previously classified by Krasil'nikov (1941) as Proactinomyces mesentericus (Orla-Jensen) Jensen 1932.

Cytoplasmic antigens from Nocardia elicting a specific delayed hypersensitivity

Purified cytoplasmic extracts from Nocardia asteroides and N. brasiliensis elicit delayed hypersensitivity in Nocardia-sensitized guinea pigs. The differences in skin reactivity clearly show that it is possible to distinguish between different Nocardia species. When peritoneal exudate cells from the latter animals were obtained and treated with the purified cytoplasmic extracts, their migration was inhibited to a significant degree only by means of the homologous antigen. A mild delayed reactivity was observed when the cytoplasmic antigens were used as skin test materials on animals sensitized with BCG. On the other hand, no inhibition of migration was observed when peritoneal exudate cells from BCG-sensitized guinea pigs were exposed to the cytoplasmic antigens.

Genophore homologies among compatible nocardiae

Deoxyribonucleic acid (DNA) reassociation analyses were employed to determine the molecular relationships between recombinable nocardiae. Analysis of the compatibility system of Nocardia erythropolis Mat-Ce and Mat-cE mating strains demonstrated the existence of extensive homology under both exacting and nonexacting conditions. Labeled N. erythropolis Mat-cE DNA reassociated equally as well with the Mat-Ce test DNA as with its own filter-bound DNA. However, the Mat-cE DNA bound only ca. 60% of the Mat-Ce DNA, when the latter was the reference. The existence of unique nucleotide sequences is postulated on the basis of these results as well as of aberrant segregation patterns which have been observed in certain class types of recombinants. Reassociation data reveal that recombinants representing the inheritance of different portions of each of the parental genomes have inherited the unique portion from the Mat-Ce parent. N. restrictus AY-B-226 exhibited little relatedness (11 to 32%), and N. globerula ATCC 9356 only slightly more (21 to 42%), to either of these mating strains at either exacting or nonexacting temperatures of incubation.

Inactivation of nocardiophages phi C and phi EC by extracts of bacteriophage-attachable cells

Cultures of several species of Nocardia, including N. erythropolis Mat-Ce and Mat-cE mating strains, were extracted with solvents in an attempt to isolate an inactivating complex for nocardiophages phiC and phiEC. Ethanol was the only solvent found effective in solubilizing an inhibitory substance. Inactivating extracts were obtained from the cells of all species to which the phage were able to attach. After extraction of whole cells or cell wall preparations, the phage could not effectively attach to them. Both phages phiC and phiEC were inactivated by the same complex. However, phage phiEC inactivation was 10-fold greater than phiC inactivation. The velocity of inactivation was about 4.1 x 10(2) plaque-forming units per microgram per minute for phiC and 1.1 x 10(3) plaque-forming units per microgram per minute for phage phiEC. The cell extracts required divalent cations for phage inactivation. The inhibitory capacity of the cell extracts was reduced or lost by the activity of proteolytic enzymes, Tween 80, 2-mercaptoethanol, thymol, and sodium lauryl sulfate. Boiling the extract for 10 min did not alter its activity. The inactivating substance was postulated to be a lipoprotein of considerable complexity, unique in the ease with which it is solubilized from host cells by ethanol.

Amino acids of the cell wall of Nocardia rubra

Two classes of preparations of cell walls of Nocardia rubra strain 721-A, digested by trypsin and pepsin with or without subsequent extraction in alkaline ethanol, when examined by electron microscope and analyzed quantitatively for amino acid content differ in ultrastructure and constituent amino acids. Evidence suggests that the lipid-associated amino acids (as peptide or protein) occupy a location superficial to the basal peptido-glycan layer of this nocardia. Their removal is associated with the loss of a characteristic pattern of the outer envelope.

Effect of substrate on fatty acid production in Nocardia asteroides

Cellular fatty acids of the six Nocardia asteroides strains grown on glucose, glucose and amino acids, glycerol, and Dubos oleic albumin complex were determined by gas–liquid chromatography. Cells grown on each medium contained saturated, unsaturated, and branched-chain fatty acids. The fatty acids consisted of normal saturated C13, C14, C15, C16, C17, and C18; monoenoic C16 and C18; branched-chain C14, C15, and 10-methyl C18. Composition of the media affected cellular fatty acid content of N. asteroides strains qualitatively and quantitatively. Five of the six strains closely resembled each other, but one strain appeared to be different. The fatty acid pattern of Nocardia may be a useful criterion in differentiation of this genus from the closely related Mycobacterium and Streptomyces, which have a different fatty acid composition.