Antimicrobial Drug Combinations

Combination antimicrobial drug therapy The use of two or more drugs together to increase efficacy more than can be accomplished with the use of a single agent... 

Drugs are considered to act additively when the activity of drugs in combination are equal to the sum of their independent activity. The overall effect of two antimicrobial drugs can be less (antagonism) or more (synergism) than the sum effect. 

Synergy studies are in vitro tests that attempt to measure synergistic, additive, indifferent, or antagonistic drug interactions. In general, these tests have not been standardized and have not correlated well with clinical outcome. (See section on Antimicrobial Drug Combinations for details.)... 

Some clinical situations in which combinations of antimicrobial drugs are indicated. 

Use of antimicrobial drugs choice combinations chemoprophylaxis and preemptive suppressive therapy... 

Combinations of beta-lactam antibiotics with antimicrobial drugs from other molecular classes are often used, especially in severe infection. 

The use of a combination of a glucocorticoid with an antimicrobial drug is illogical and should generally be avoided because of the possibility of the emergence of resistant bacterial strains. It would be highly preferable if prescriptions for these drugs were issued by... 

Finland M. Editorial Combinations of antimicrobial drugs trimethoprim-sulfamethoxazole. N Engl J Med 1974 291(12) 624-7. 

Combination antimicrobial therapy is commonplace in equine practice. However, combination therapy has never been demonstrated to be superior to single drug therapy in controlled clinical trials. The use of multiple antimicrobial agents should be limited to certain situations. 

Aminoglycosides The aminoglycosides are important antimicrobial drugs used alone or in combination with )S-lactam antibiotics for the treatment of certain serious gram-negative infections. Chemically, the aminoglycosides consist of various sugars... 

Fig. 6.4 Types of combined action of two antimicrobial drugs on a homogeneous microbial population. Schematic representation of bactericidal action in vitro showing the possible types of results seen when one drug, or two drugs, act on a homogeneous population of bacteria under conditions permitting growth.

Jawetz, E. (1975) Combined actions of antimicrobial drugs. In Concepts in Biochemical Pharmacology, Part 3, (eds J.R. Gillette J.R. Mitchell), pp. 343-358. Springer-Verlag, Berlin. 

Rybak Ml, McGrath BJ. Combination antimicrobial therapy for bacterial infections Guidelines for the clinician. Drugs 1996 52 390-405. 

Korzeniowski O, Sande MA. The National Collaborative Endocarditis Study Group Combination antimicrobial therapy for Staphylococcus aureus endocarditis in patients addicted to parenteral drugs and in nonaddicts. Ann Intern Med 1982 97 496-503. 

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