Health and Prostate

The use of antibiotic combinations for the treatment of bacterial infections has been the subject of many reviews (Garrod 1953, 1964, Chabbert 1953, Dowling 1957, Jawetz 1958, Lacey 1960). All the authors take the view that double chemotherapy is only justified for certain specific reasons, and condemn factory-made mixtures of antibiotics, on the grounds that it is important to prescribe the two antibiotics in appropriately chosen doses. Moreover, the trade name of a mixture often gives no indication of the drugs it contains and may suggest to the uninitiated that it is a new antibiotic, rather than a mixture of two well known ones.

The reasons suggested for double chemotherapy are:
(1) To achieve a synergic effect.
(2) To delay the emergence of resistant strains.
(3) To prevent super infection.
(4) To treat relatively inaccessible bacteria.
(5) To treat mixed infections.
(6) To treat undiagnosed infections.

In addition some people have recommended the use of two drugs in order to achieve good therapeutic results with small doses of drugs which would be too toxic to use in larger doses, but this has not proved to be of much practical value.

The first three of these reasons are the most important and will be discussed at length. The last three are briefly referred to below.

Inaccessible Bacteria

The most important example of this is in relation to the treatment of brucellosis with streptomycin. Brucella spp. tend to be intracellular and streptomycin does not readily penetrate cells. Shaffer et al. (1953) showed that Brucella suis was about 25,000 times less sensitive to streptomycin when injected in leucocytes than when free. This is probably the reason why combined therapy with tetracycline and streptomycin is more effective in the treatment of brucellosis than is treatment with streptomycin alone. Myco. tuberculosis also tends to be intracellular and since isoniazid readily penetrates cells, combined treatment with isoniazid and streptomycin is to be recommended, quite apart from the problem of drug resistance.

Mixed Infections

In mixed infections a single narrow-spectrum antibiotic may be effective, but, if not, two antibiotics, for example benzylpenicillin and streptomycin, are often more efficient, and may also be cheaper, than a broad-spectrum antibiotic.

Undiagnosed Infections

It is important to make a bacterial diagnosis before starting antibiotic treatment whenever possible. In the seriously ill, however, early treatment is important and must be started as soon as appropriate specimens have been sent to the bacteriological laboratory. The selection of antibacterial drugs for such cases is difficult. If the infection has developed in hospital, the antibiotic sensitivity pattern of likely infecting organisms may be known. Sometimes the clinical picture may give a lead. For blind antibiotic therapy in very ill patients treatment with methicillin, ampicillin and polymyxin is possibly the widest bactericidal combination.