Vancomycin gastrointestinal infections

Vancomycin is not absorbed after oral administration and must be given intravenously. Oral administrations are used for intraluminal gastrointestinal infections such as antibiotic-associated pseudomembranous colitis produced by Clostridium difficile. Vancomycin is widely distributed in the body but does not cross the blood brain barrier and does not penetrate into bone. It is excreted mainly via the urine, resulting in accumulation in patients with renal insufficiency. Its elimination half-life is 4-11 hours but can increase to 6-10 days in renal failure. 

Because of its potential toxicity, vancomycin is reserved for serious infections in which less toxic antibiotics are ineffective or not tolerated. Generally, vancomycin is administered intravenously because of poor intestinal absorption. It is the drug of choice for treating infections caused by methicillin-resistant staphylococci and penicillin-resistant Streptococcus pneumoniae. Vancomycin has been used to treat enterococcal infections because of their resistance to the P-lactam antibiotics, but most enterococci are now also resistant to vancomycin. Oral administration of rancomycin is important for treatment of some gastrointestinal infections such as pseudomembranous colitis caused by C. difficile. 

Chloramphenicol, isolated in 1947, is a broad spectiarm antibiotic. It is rapidly absorbed from the gastrointestinal tract and hence can be given orally in case of typhoid, dysentery, acute fever, certain form of urinary infections, meningitis and pneumonia. Vancomycin and ofloxacin are the other important broad spectr-um antibiotics. The antibiotic dysidazirine is supposed to be toxic towards certain strains of cancer cells. 

Infections limited to soft tissue will require between 7 and 10 days of intravenous therapy followed by an additional 14 days of oral therapy (total duration 2-4 weeks). If MRSA is isolated, intravenous vancomycin must not be switched to oral vancomycin which has negligible absorption from the gastrointestinal tract. Oral agents may be selected from rifampicin, tetracyclines, fusidic acid or trimethoprim depending on sensitivity data and a combination of two agents is recommended. Oral linezolid monotherapy is an effective alternative. 

Vancomycin is particularly useful in infections caused by meticillin-resistant or penicillinase-producing staphylococci and diphtheroids, as well as in the prophylaxis of bacterial endocarditis and in the treatment of antibiotic-associated colitis. Sufficient fecal concentrations can be achieved with oral therapy. It is poorly absorbed from the gastrointestinal tract and painful when injected intramuscularly. It diffuses moderately well into bone tissue (6). 

Pogue JM, DePestel DD, Kaul DR, Khaled Y, Frame DG. Systemic absorption of oral vancomycin in a peripheral blood stem cell transplant patient with severe graft-versus-host disease of the gastrointestinal tract. Transpl Infect Dis 2009 11(5) 467-70. 

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