Penicillin G is highly active against most Gram-positive cocci, Gram-positive rods, Gram-negative cocci, and anaerobes. Exceptions are bacteria from these classes that have acquired resistance to penicillin as well as certain anaerobes that produce a beta-lactamase such as Bacteroides. Penicillin is only bacteriostatic against enterococci.
For strains of S. aureus sensitive to oxacillin, antistaphylococcal penicillins are preferable to vancomycin because they are more active in vitro and in clinical studies.
Broad spectrum penicillins have increased activity over penicillin G against Gram-negative bacilli but are variably inactivated by beta-lactamases.
All penicillins have relatively short half-lives and require frequent administration when given parenterally. CSF penetration is poor except in the presence of inflammation. The anti-staphylococcal penicillins need no dose modification when used in the setting of renal failure.
Penicillin G 詳細に
●Gram-positive cocci (except penicillinase-producing staphylococci, penicillin-resistant pneumococci, enterococci, and oxacillin-resistant staphylococci)
●Gram-positive rods such as Listeria
●Gram-negative cocci such as Neisseria spp (except penicillinase-producing Neisseria)
●Most anaerobes (with certain important exceptions, including Bacteroides)
Penicillin G is only bacteriostatic for enterococci; reports document strains with increasing intrinsic resistance to penicillin and, rarely, with high level resistance due to penicillinase production．Serious infections with enterococci are generally treated with combination therapy of a cell wall active antibiotic such as penicillin, ampicillin, or vancomycin plus gentamicin or streptomycin (unless high level resistance to these aminoglycosides is present). Penicillin G is not active against gram-negative bacilli because of poor penetration through the porin channel.
Resistance to penicillin and cephalosporin and mortality from severe pneumococcal pneumonia in Barcelona, Spain. - PubMed - NCBI
Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States. - PubMed - NCBI