Bacteria bacteriostatic effect

It has been known for some time that tetracyclines are accumulated by bacteria and prevent bacterial protein synthesis (Fig. 4). Furthermore, inhibition of protein synthesis is responsible for the bacteriostatic effect (85). Inhibition of protein synthesis results primarily from dismption of codon-anticodon interaction between tRNA and mRNA so that binding of aminoacyl-tRNA to the ribosomal acceptor (A) site is prevented (85). The precise mechanism is not understood. However, inhibition is likely to result from interaction of the tetracyclines with the 30S ribosomal subunit because these antibiotics are known to bind strongly to a single site on the 30S subunit (85). 

The effect of antibacterial drugs can be observed in vitro (3). Bacteria multiply in a growth medium under control conditions. If the medium contains an antibacterial drug, two results can be discerned 1. bacteria are killed—bactericidal effect 2. bacteria survive, but do not multiply-bacteriostatic effect Although variations may occur under therapeutic conditions, different drugs Lullmann, Color Atlas of Pharmacology... 

The sulfonamide antibiotics were the first synthetic antibiotics to have general utility in human therapy (B-79MI10806). Of the numerous compounds thus developed, comparatively few are presently used in veterinary practice. They include sulfapyridine (40), sulfamethazine (41) and sulfadimethoxine (42). They are much less potent than the /3-lactams (dose 100-200 mg kg-1), and have a bacteriostatic effect. They are commonly used in combination with trimethoprim (43), when a synergistic effect is observed, i.e. the combination is more potent than either drug alone, and species of bacteria which are unaffected by the drugs individually are susceptible to the combination. 

It has been known for some time that tetracyclines arc accumulated by bacteria and prevent bacterial prutein synthesis. Furthermore, inhibition of protein synthesis is responsible for the bacteriostatic effect. Inhibition... 

Oxazolidinones, such as linezolide, are a newly discovered drug group (p.281). They inhibit initiation of synthesis of a new peptide strand at the point where ribosome, mRNA, and the start-tRNA-AA complex aggregate. Oxazolidinones exert a bacteriostatic effect on Gram-positive bacteria. Since bone marrow depression has been reported, hematological monitoring is necessary. 

Before performing a product bacteria challenge test, it has to be assured that the liquid product does not have any detrimental, bactericidal or bacteriostatic, effects on the challenge organisms. This is done utilizing viability tests. The organism is inoculated into the product to be filtered at a certain bioburden level. At specified times, the log value of this bioburden is tested. If the bioburden is reduced due to the fluid properties, a different bacteria challenge test mode becomes applicable. ... 

Although macrolides can bind to 238 ribosomal RNAs of both gram-positive and gram-negative bacteria, incorporation and accumulation of sufficient amounts of macrplide into the cells are necessary to exhibit bactericidal or bacteriostatic effect. 

Lincomycin (Lincocin) has been used in the past to treat serious streptococci, pneumococci, and staphylococci infections but has generally been replaced by safer and more effective antibiotics. Clindamycin (Cleocin) is a semisynthetic derivative of lincomycin and has a similar mechanism but is more effective. It is indicated for the treatment of bone and joint infections, pelvic (female) and intraabdominal infections, bacterial septicemia, pneumonia, and skin and soft tissue infections. In a normal dose, lincosamides prevent the growth of bacteria (bacteriostatic). In larger doses, it kills bacteria (bacteriocidal). 

The bacteriostatic effect can only be achieved through exact adherence to the use-concentration, since the biological effect is only inhibition of growth (i.e. reversible damage) if the environmental conditions are altered by the inhibitory concentration not being reached, the bacteria can re-enter the growth phase. 

Lactic acid (pJC = 3.83 at 25 °C, see Section 8.2.6.1.3) occurs as a natural compound in many fermented products (e.g. yoghurt, fermented sauerkraut and olives). As a preservative, lactic acid (E270) is mainly used as an addulant The undissociated form diffuses through cell membrane of many bacteria and lowers the pH within the cell. It has a bacteriostatic effect on pathogenic bacteria Mycobacterium bovis, a member of the M. tuberculosis bacteria, the causative agent of bovine tuberculosis in cattle. Lactic acid is also effective against other bacteria, so it is used, for example, for surface decontamination of meat and in production of dehcacies. Usually it is applied in combination with sodium lactate. 

The solubility of dihydrostreptomycin sulphate, which is water soluble, is decreased in concentrated solutions of sorbitan monolaurate (E = 12) [129]. Streptomycin sulphate is also very soluble in water and is incompatible with sodium lauryl sulphate. Combination of streptomycin with polysorbate 20 produces a strong bacteriostatic effect against antibiotic resistant bacteria. Intrapleural injection of 0.5 g dihydrostreptomycin with one drop of polysorbate 20 in 4 ml has been reported to result in a sterile pleural sample 1 week after injection [130]. 

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