Gram-positive mycobacteria

Fifty-six years ago the very first siderophore, mycobactin, was isolated by the crystallization of the aluminum complex. Mycobactins from Gram-positive Mycobacteria and the closely related nocobactins from Nocardia embody a series of lipid-soluble siderophores located in the lipid-rich boundary layers of these bacteria (Figure 2(c)). The X-ray structure revealed that iron binding in mycobactins is accomplished by two hydroxamates, a phenolate group, and oxazoline nitrogen. 

Activity against gram-positive bacteria = P gram-negative bacteria = N mycobacteria = M fungi = F tumors = T and viruses = V. Only peptides not discussed in the text of this article are given references. 

Sulfurmycin B (active again.st Gram-positive bacteria, mycobacteria, and tumors)... 

Others (against mycobacteria) Clofazimine, ethionamide, and rifampicin Gram-positive and mycobacteria... 

Figure 7. The summary of systems involved in (or related to) the uptake and assimilation of iron represents a schematic view of a typical Gram-negative bacterium. The OM receptors, as well as the proteins of the Ton complex, are not present in Gram-positive bacteria, and were not found in mycobacteria and members of the mycoplasma group...

Rifampin inhibits the bacterial enzyme that catalyzes DNA template-directed RNA transcription, i.e DNA-de-pendent RNA polymerase. Rifampin acts bactericidally against mycobacteria (M. tuberculosis, M. leprae), as well as many gram-positive and gram-negative bacteria It is well absorbed after oral ingestion. Because resistance may develop with frequent usage, it is restricted to the treatment of tuberculosis and leprosy (p. 280). 

Activity spectrum. Disinfectants inactivate bacteria (gram-positive > gram-negative > mycobacteria), less effectively their sporal forms, and a few (e.g, formaldehyde) are virucidal. 

Antibacterial activity of macrolides depends on the acidity of the medium. High activity is observed in neutral and basic media in comparison with acid. In particular, erythromycin is inactivated in the acidic medium of the stomach. Macrolides have a relatively broad spectrum of use, and they are active with respect to Gram-positive and Gram-negative microorganisms, achiomycetes, mycoplasma, spirochaeta, chlamydia. Bacteria Rickettsia, certain mycobacteria. Colon bacillus, blue-pus bacillus, shigella, salmonella, and so on. 

Resistance of Gram-negative organisms (such as mycobacteria), fungi, virii, and prota-zoans to vancomycin occurs because the barrier is impermeable to the drug, which is ensured by the outer membrane. Resistance of Gram-positive organisms to vancomycin is rarely observed. 

May be effective in the treatment of acute urinary tract infections caused by susceptible strains of gram-positive and gram-negative bacteria, especially Enterobacter sp. and Escherichia coii. It usually is less effective than other antimicrobial agents in the treatment of urinary tract infections caused by bacteria other than mycobacteria. Consider using only when the more conventional therapy has failed and when the organism has demonstrated sensitivity. 

Ansamycins, like the macrolides, are synthesized by condensation of a number of acetate and propionate units. These antibiotics, which are produced by several genera of the Actinomy-cetales, display a characteristic core aromatic ring structure. Amongst the best-known family members are the rifamycins, which are particularly active against Gram-positive bacteria and mycobacteria. They have been used, for example, in the treatment of Mycobacterium tuberculosis. 

Rifampicin, a semisynthetic derivative of the antimicrobial agent rifamycin B obtained from Strep-tomyces mediterranei, is bactericidal for intra- and extracellular bacteria. Bacterial RNA synthesis is inhibited by binding to the beta-subunit of DNA-dependent RNA polymerase. Human polymerases are not affected. It has activity against gram-positive and gram-negative cocci, chlamydia as well as mycobacteria. It is used in combination with dapsone for leprosy. 

It is difluorinated quinolone effective against gram positive bacteria, anaerobes and mycobacteria. It is used in the treatment of pneumonia, chronic bronchitis, sinusitis etc. 

Rifampin is a semisynthetic derivative of rifamycin, an antibiotic produced by Streptomyces mediterranei. It is active in vitro against gram-positive and gram-negative cocci, some enteric bacteria, mycobacteria, and chlamydia. Susceptible organisms are inhibited by less than 1 mcg/mL. Resistant mutants are present in all microbial populations at... 

Biological Properties. The in vitro activity is such that oligosaccharides, in general, are highly potent, but are narrow-spectrum antibiotics. Everninomicins are active against a wide variety of gram-positive aerobes and anaerobes Neisseria, Mycoplasma, and some Mycobacteria. Comparatively, nambamycin is less potent Ilian everninomicin D. 

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