Info

Adapted with permission from Drug Facts and Comparisons. St.

Louis: Lippincott, 1985:1372.

Two other common mechanisms of resistance are known. Some cases of resistance of aerobic gramnegative bacilli to streptomycin are due to mutations in the proteins of the bacterial ribosomes. Streptococci, staphylococci, and Pseudomonadaceae resist aminogly-cosides as a result of decreased transport of the amino-glycosides into the bacterial cytosol.

Anaerobes also are resistant to aminoglycosides because of decreased transport into the bacterial cytosol. Combining an aminoglycoside with an antibiotic that disrupts the bacterial cell wall can overcome this natural resistance.

Adapted with permission from Drug Facts and Comparisons. St.

Louis: Lippincott, 1985:1372.

The postantibiotic effect is characterized by prolonged suppression of bacterial regrowth after the initially high aminoglycoside concentration has fallen to a subinhibitory level. Perhaps resumption of bacterial ri-bosomal function requires the time-consuming synthesis of new ribosomes after their disruption by aminogly-cosides. The postantibiotic effect explains why aminoglycosides can be given in single daily doses despite their short half-life.

Penetration of aminoglycosides through the outer bacterial membrane occurs both by outer membrane disruption and by diffusion through outer membrane porins. Penetration through the inner bacterial membrane occurs in two phases. The first requires that the cytosol have a negative electron potential and therefore be inhibited by the presence of a low pH. The second phase depends on aerobic bacterial metabolism and therefore will be inhibited by low oxygen tension. The latter two observations are of considerable clinical relevance, since both a low pH and a low oxygen tension frequently occur in bacterial abscesses. Administration of p-lactam antibiotics will reverse the negative effects of both low pH and low oxygen tension on the ability of aminoglycosides to penetrate into bacteria; this ability accounts in part for the synergism that occurs between aminoglycoside and p-lactam antibiotic drugs.

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment