Narrow-spectrum antibiotics

The antibiotic of choice for group B streptococcal disease is penicillin G, although ampicillin is an alternative.43 No resistance to either agent has been reported, and their narrow spectrum of activity makes them ideal choices.43 Resistance has developed with the use of alternative choices for penicillin-allergic patients. A treatment algorithm for group B Streptococcus is shown in Fig. 44—3, and dosing recommendations are shown in Table 44-5. 

Oral, narrow-spectrum antibiotic therapy with activity against Staphylococcus aureus and streptococcal species. Include coverage for MRSA (HA- or CA-MRSA) according to patient history and resistance patterns in the area. 

Johnson AP. (2007) OPT-80, a narrow-spectrum macrocyclic antibiotic. Curr Opin Invest Drugs 8 168-173. 

Three broad groupings, of the antibiotic substances presently used in animal production, include (a) broad-spectrum antibiotics, including penicillins and tetracyclines, which are effective against a wide variety of pathogenic and non-pathogenic bacteria (b) several narrow-spectrum antibiotics that are not used in human medicine and. (c) the ionophore antibiotics, monensin. lasalocid and salinomycin Monensin and lasalocid are used as rumen fermentation regulators in beef cattle, and the three ionophores are used as coccidiostats in poultry production. The ionophores. which are not used in human medicine, were first introduced in the 1970 s and account for most of the increase in antibiotic usage in animal production since the 1960 s. 

Topical formulations of nystatin and of amphotericin B are useful in the management of Candida albicans infections of the skin. Both antibiotics are ineffective against dermatophytes. The use of nystatin is limited to topical treatment of cutaneous and mucosal Candida infections because of its narrow spectrum and its negligible absorption from the gastrointestinal tract. Hypersensitivity reactions are rare. It is not known whether topical nystatin can cause fetal harm when used by a pregnant woman. Amphotericin B has broader antifungal activity but its topical use is restricted to Candida. Topical use of amphotericin B has shown minimal absorption through the skin and is well tolerated. Limited human surveillance data do not indicate any harm to mother or fetus, but relative safety is still unknown. 

Novobiocin (Fig. 3.9) is a narrow-spectrum antibiotic with antibacterial activity against many gram-positive pathogens. It is frequently used, in combination with penicillin, for treatment of bovine mastitis by intramammary infusion of 200 mg/ quarter in two quarters, and to control fowl cholera and staphylococcal infections in chickens and turkeys at a level of 200-350 g/ton in feed. 

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. 

Topical antibiotics with a narrow spectrum of action and low toxicity (eg, bacitracin and mupirocin) can be used for temporary control of bacterial growth and are generally preferred to antiseptics. Methenamine mandelate releases formaldehyde in a low antibacterial concentration at acid pH and can be an effective urinary antiseptic for long-term control of urinary tract infections. 

Search for genes that are unique to a particular organism to identify candidates for narrow-spectrum antibiotic development. 

Correct answer a D. Amoxicillin plus clavulanic acid is an extended spectrum formulation that is penicillinase resistant because of the presence of a p-lactamase inhibitor, and is stable in acid. Methicillin, an antistaphylococcal penicillin, is penicillinase resistant but is not stable in acid. Carbeniciliin and piperacillin, antipseudomonai penicillins, are neither penicillinase resistant nor stable in acid. Penicillin V is a narrow spectrum antibiotic that is not penicillinase resistant but is stable in acid. 

Penicillin V is a narrow-spectrum penicillin and has similar antibacterial activity to benzylpenicillin. It is active against many streptococcal infections, but it is inactivated by penicillinases. Flucloxacillin is a penicillinase-resistant antibiotic and is effective against infections caused by penicillin-resistant staphylococci. In comparison to penicillin V, attachment of carbocyclic/heterocyclic ring directly to the C6 carbonyl group confers resistance to beta-lactamases due to steric hindrance around the amide group. 

The most active metabolite was the novel cyclic undecapeptide, cyclosporin A (Figure 8). As an antibiotic, cyclosporin A exhibited only a very narrow spectrum of modest antifungal activity, but in 1972 its true potential was realised. Jean Borel and colleagues at Sandoz discovered that cyclosporin A also neutralised cytotoxic T-cell activity in vitro and prevented haemagglutination in mice immunised against sheep erythrocytes. Further studies revealed that cyclosporin A inhibits T-cell proliferation by blocking the synthesis of IL-2. ... 

Vancomycin is a narrow-spectrum glycopeptide antibiotic with potent antistaphylococcal activity. It was developed in the early 1950s. Early formulations contained substantial impurities, which were presumably responsible for some adverse reactions (1). When rapid infusion rates are avoided, vancomycin is rarely associated with serious toxicity. Reviews have suggested that the potential for vancomycin to cause significant ototoxicity or nephrotoxicity has been exaggerated (2,3). Improved manufacturing has resulted in a purer product and fewer toxic effects, but vancomycin is still associated with potentially serious adverse reactions (4). 

Griseofiilvin is a narrow-spectrum antifungal antibiotic with fungistatic properties, which is mainly used for large-scale ringworm (dermatophytic) infections of the skin, nails, scalp and hair. 

P NMR has been used to investigate the effects of three anti-microbial peptides isolated from Australian tree frogs Litoria caerulea and L. genimacu-lata on the cell membranes of Bacillus cereus and Staphylococcus epidermidis. The wide-spectrum antibiotic peptides caerin 1.1 and maculatin 1.1 disrupted cell membranes causing an increase in the isotropic P NMR signal. However, caerin 4.1, a narrow-spectrum antibiotic, did not affect the P spectra of these bacteria. ... 

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