Spectrum of Antibacterial Activity

In order to overcome the limitations of the above drugs, a series of rifamycin derivatives with improved pharmacokinetic (i.e. virtually absence of GI absorption) and pharmacodynamic (i.e. with broad spectrum of antibacterial activity) properties have been synthesized at Alfa Wassermann laboratories [33]. Amongst the different molecules, the compound marked L-105 and later... 

Much information on the mechanism of action and cross-resistance of purine analogues has been obtained in bacteria, some of which are quite sensitive to certain of these compounds in vitro. There is a great deal of variation in response of the various bacteria to a particular agent and of a particular bacterium to the various cytotoxic purine analogues. Some, if not most, of these differences are probably due to differences in the anabolism of the various compounds. Despite the fact that certain purine analogues have quite a spectrum of antibacterial activity in vitro, none has been useful in the treatment of bacterial infections in vivo because their toxicity is not selective—the metabolic events whose blockade is responsible for their antibacterial activity are also blocked in mammalian cells and thus inhibition of bacterial growth can only be attained at the cost of prohibitive host toxicity. In contrast, the sulpha drugs and antibiotics such as penicillin act on metabolic events peculiar to bacteria. 

Because of its pharmacokinetic features (pronounced bioaccessability upon oral use, diffusion to tissues and permeation into them, broad spectrum of antibacterial activity, and so on), fluoroquinolones have considerable potential for treating infections of practically any anatomic localization. Fluoroquinolones are very effective in treating infections of the respiratory tract, urinary tract, bones, skin, soft tissues, and so on. 

Streptomycin possesses a broad spectrum of antibacterial activity. It is the first clinically effective drug used for treating tuberculosis. Synonyms of this drug are streptan, strepto-col, and others. 

Loracarbef Lorabid) is a synthetic p-lactam antibiotic of the carbacephem class. The chemical structure of loracarbef is similar to that of cefaclor. Selected pharmacokinetic information appears in Table 45.2. Lora-carbef s spectrum of antibacterial activity resembles those of the second-generation cephalosporins. Comparative clinical trials reveal similar outcomes in patients treated with cefaclor, cefprozil, and loracarbef. 

The unique advantages of piperacillin are broad spectrum of antibacterial activity and excellent antipseudomonal activity. 

Phenanthroline inhibits proline incorporation into proteins.391,392 Benzo-substituted-l,8-phenanthrolines and 1,10-phenanthrolines are amoebicides.180 l,8-Phenanthroline-8-oxide has a wide spectrum of antibacterial activity.393... 

As indicated in Table 33-2, penicillins can be classified according to their chemical background, spectrum of antibacterial activity, or pharmacokinetic features.56 The naturally occurring penicillins (penicillin G and... 

Erythromycin and the other macrolides exhibit a very broad spectrum of antibacterial activities and are active against many gram-positive bacteria, as well as some gram-negative bacteria. These agents are often used as the primary or alternative drug in a variety of clinical conditions (see Table 33-5). Macrolides may be especially useful in patients who are allergic to penicillin. 

Cecropins 224) are produced in insects on account of the lack of lymphocytes and immunoglobulins by a humoral immune reaction, and have a broad spectrum of antibacterial activity. 

Clarithromycin has a spectrum of antibacterial activity similar to that of erythromycin, but is also effective against Haemophilus influenzae. Its activity against intracellular pathogens such as Chlamydia. Legionella and Ureaplasma is higher than that of erythromycin (Figure 31.9). 

To broaden the spectrum of antibacterial activity (1) in a known mixed infection, e.g. peritonitis following gut perforation or (2) where the infecting organism cannot be predicted but treatment is essential before a diagnosis has been reached, e.g. septicaemia complicating neutropenia or severe community-acquired pneumonia full doses of each drug are needed. 

Organic mercurials mercury, silver, thiomersal, phenylmercuric acetate Broad spectrum of antibacterial activity Low capacity to organic matter, ionic and some non-ionic surfactants toxicicity Eye drops contact lens solutions... 

F. foliacea also occurs in the Bay of Fundy, Canada. Bioassay-guided fractionation based on antibacterial activity of the extract of this bryozoan has lead to the isolation of a different series of bromoal-kaloids of the physostigmine class, two of which were N-oxides (39]. The major alkaloids were dihydroflustramine C, 90, ( 60%), which had been reported previously by these authors [40) and flustramine D, 91, (-40%). Minor alkaloids found were dihydroflustramine C N-oxide, 92. flustramine D Af-oxide, 93, and isoflutramine D, 94. The JV-oxides were also synthesised by oxidation of the corresponding free bases with m-chloroperbenzoic acid. These alkaloids were shown to be responsible for the wide spectrum of antibacterial activity exhibited by this bryozoan extract. 

Examples of other antibacterial crude extracts from the Anthemideae tribe also included methanol extracts of the leaves of Tagetes terniflora Kunth [39], the benzene fraction of Vernonia cinerea L. which exhibited a broad spectrum of antibacterial activity against Bacillus subtilis and Pseudomonas aeruginosa [40], Aster ageratoides Turcz. [41] and Xanthium strumarium L. extracts which were active against several strains of bacteria, yeasts and fungi [42]. 

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