Gram-positive organisms, antibiotic

Because of the highly permeable nature of the ced wad of gram-positive organisms, they produce P-lactamases which are not only found throughout the ced wad, but also in the extracedular environment. Hence the extracedular P-lactamases can act on the antibiotic before the ced is entered. 

Initial antibiotic choice should always cover gram-positive organisms (e.g., vancomycin 20 mg/kg intravenously with serum concentration monitoring or cefazolin 20 mg/kg intravenously 3 times... 

Even newer is the natural product daptomycin (Cubicin), a complex cyclic lipopeptide structure, approved for use in the United States in 2003. Daptomycin has a spectrum similar to that of linezolid and specifically includes MRSA and VRE. In contrast to linezolid, daptomycin is bactericidal for these Gram-positive organisms. It is, like vancomycin, a parenteral antibiotic and is given intravenously. It is indicated for treatment of complicated skin and skin structure infections and for some cases of bacteremia, including endocarditis. Daptomycin may be thought of as an alternative to vancomycin. 

Bacitracin and gramicidin are polypeptide antibiotics with activity against gram-positive organisms and against most anaerobic cocci. Systemic toxicity for bacitracin is rare because of poor absorption through the skin. Gramicidin is used only topically... 

An additional mechanism of antibiotic resistance involves an alteration of PBPs. Resistant bacteria, usually gram-positive organisms, produce PBPs with low affinity for p-lactam antibiotics. The development of mutations of bacterial PBPs is involved in the mechanism for p-lactam resistance in Streptococcus pneumoniae. Enterococcus faecium, and methicillin-resistant S. aureus (MRS A). 

Bacitracin and gramicidin are peptide antibiotics, active against gram-positive organisms such as streptococci, pneumococci, and staphylococci. In addition, most anaerobic cocci, neisseriae, tetanus bacilli, and diphtheria bacilli are sensitive. Bacitracin is compounded in an ointment base alone or in combination with neomycin, polymyxin B, or both. 

Nisin is an antibacterial polypeptide produced by some strains of Lactococcus lactis. Nisin-like substances are widely produced by lactic acid bacteria. These inhibitory substances are known as bacteriocins. Nisin has been called an antibiotic, but this term is avoided because nisin is not used for therapeutic purposes in humans or animals. Nisin-producing organisms occur naturally in milk. Nisin can be used as a processing aid against gram-positive organisms. Because its effectiveness decreases as the bacterial load increases, it is unlikely to be used to cover up unhygienic practices. 

From a polysaccharide of the Gram-positive organism BaciUus svbtilis, a related sugar has been isolated but not fully characterized it is a 4-acetamido-2-amino-2,4,6-trideoxyhexose. Another diamino sugar, a 2,6-diamino-2,6-dideoxyglucose, has been isolated from the antibiotic substance Neomycin. ... 

Initial treatment of bacterial ophthalmia neonatorum should be directed by the results of conjimctival smears. Broad-spectrum antibiotics with low toxicity should be used. Topical erythromycin or tetracycline ointment can be used four to six times daily fc>r gram-positive organisms, and gentamicin or tobramycin solution four to six times daily can be started if gram-negative organisms are isolated. Trimethoprim-polymyxin B (Polytrim) has... 

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