A diabetic patient develops cellulitis due to staphy-lococcus aureus that was found to be methicillin resistant on the antibiotic sensitivity testing.All of the following antibiotics will be appropriate EXCEPT:
lmipenem: It is an extremely potent and broad-spectrum Beta-lactam antibiotic whose range of activity includes grampositive cocci, Enterobacteriaceae, Ps. aeruginosa, Listeria as well as anaerobes like Bact. fragilis and Cl. difficile. It is resistant to most Beta-lactamases; inhibits penicillinase producing staphylococci and some MRSA. A limiting feature of imipenem is its rapid hydrolysis by the enzyme dehydropeptidase I located on the brush border of renal tubular cells. An innovative solution to this problem is its combination with cilastatin, a reversible inhibitor of dehydropeptidase I, which has matched pharmacokinetics with imipenem (Half life of both is 1 hr) and protects it.Imipenem has propensity to induce seizures at higher doses and in predisposed patients. Diarrhoea, vomiting and skin rashes are the other side effects. Vancomycin: It is a glycopeptide antibiotic discovered in 1956 as a penicillin substitute which has assumed special significance due to efficacy against MRSA Strep. viridans, Enterococcus and Cl. difficile. It is bactericidal to gram-positive cocci, Neisseria, Clostridia and diphtheroids. However, in hospitals where it has been extensively used for surgical prophylaxis, etc., vancomycin-resistant Staph. aureus (VRSA) and vancomycin-resistant Enterococcus (VRE) have emerged. These nosocomial bacteria are resistant to methicillin and most other antibiotics as well. Linezolid: This is the first member of a new class of svnthetic AMAs &;Oxazolidinones&; which has become available for the treatment of resistant Gram positive coccal (aerobic and anaerobic) and bacillary infections. It is active against MRSA and some VRSA, VRE, penicillin-resistant Strep. pyogenes, Strep. viridans and Strep. pneumoniae, M.tuberculosis, Corynebacterium, Listeria, Clostridia and Bact. Fragilis. It is primarily bacteriostatic,but can exe cidal action against some streptococci, pneumococci and B. fragilis. Gram negative bacteria are not affected. Teicoplanin: It is a newer glycopeptide antibiotic which in fact is a mixture of 6 similar compounds. It is active against gram-positive bacteria only; mechanism of action and spectrum of activity is similar to vancomycin. Notable features are: * It is more active than vancomycin against enterococci, and equally active against MRSA. * Some VRE but not VRSA are susceptible to teicoplanin. * It can be injected i.m. as well; is excreted by kidney; dose needs to be reduced in renal insufficiency; has a very long tth (3--4 days). * Toxicity is less than vancomycin; adverse effects are rashes, fever, granulocytopenia and rarely hearing loss. Reactions due to histamine release are rare (1 in 2500). ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:708,709,732,733
Vancomycin
Imipenem
Teicoplanin
Linezolid
Chemotherapy