Gram-positive bacteria antimicrobial activity

HMR 1043, discovered by the Aventis group, exhibits good antimicrobial activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro is less influenced by the presence of calcium ions than that of daptomycin l... 

The majority of scientific papers report the antimicrobial effects of different parts (peel, seed) of the fruit. Grapefruit peel extracts are effective especially against Gram positive bacteria. Similar activity has been reported for the limonoids of the seeds. In one experiment, a product containing grapefruit seed extract proved to be effective agaiirst several bacterial straiirs. This activity was ascribed to some qua-... 

Benzylpenicillin or penicillin G has a narrow antimicrobial spectrum. It is active with respect to Gram-positive bacteria (staphylococcus, streptococcus, and pneumococci), causative agent of diphtheria, and anthrax bacillus. Gram-negative bacteria are resistant to it. Benzylpenicillin is broken down by stomach acid and destroyed by staphylococcus penicillinase. 

To compare the bactericidal efficacy of silver nanoparticles and silver ions, the minimum inhibitory concentration (MIC) assays were conducted for gram-negative bacterium E. coli, gram-positive bacteria S. aureus and B. subtilis and fungus P. phoeniceum. The data on MICs are summarized in Table 18.1. The results demonstrated that the antimicrobial activity of silver ions was superior to that of silver nanoparticles against all microbes tested. 

Pure compounds 11 and 48-52 isolated from the aerial parts of L. heteromorpha var. heteromorpha showed antimicrobial activity, with a different spectrum of action, on Gram-positive bacteria and yeasts (Table... 

A related antibiotic, chromoxymycin [186], isolated from S. rubropurpureus No. 6362, is active against P388 leukaemia and B16 melanoma and exhibits antimicrobial activity against Gram-positive bacteria. The structure of chromoxymycin is very close to that of hedamycin, except that the C-l2 quinone-carbonyl is reduced and attached to a 5-[(2-carboxyethyl)aminocarbonyl]-Ar-hydroxypyrrol-2-yl moiety, and that the iV V-dimethylvancosamine attached to C-10 is no longer in the boat conformation (as in hedamycin), but rather in the chair conformation. All the other substituents remain the same. 

Newly synthesized compounds 22, 23, 25c-e, 26d and 29e were screened in vitro for their antimicrobial activities against Gram positive bacteria Staphylococcus aureus (NCTC-7447), Bacillus cereus (ATCC-14579) and Gram negative bacteria Serratia marcesens (IMRU-70) and Proteus merabitis (NTCC-289) using the paper disk diffusion method for the antibiotic sensitivity technique [60]. The tested compounds were dissolved in N,N-dimclhylformamidc (DMF) to obtain a 1 mg/mL solution. The inhibition zones of microbial growth produced by different compounds were measured in millimeters at the end of an incubation period of 48 h at 28 °C. DMF alone showed no inhibition zone. 

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