Sublethal concentrations of antibiotics, effects on bacteria and the immune system.

Biological specimens obtained from patients with infections that are treated with antibiotics at dosages that resulted in body fluid concentrations below those that are minimally inhibitory, exhibit abnormal forms of bacteria. Identical morphological changes can be induced in vitro when the parental normal forms of the bacteria. Identical morphological changes can be induced in vitro when the parental normal forms of the bacteria are exposed to subminimal concentrations of certain antibiotics. The phenomenon of induced abnormal morphology and ultrastructure has received consideration in terms of: (1) the relationship of the induced alterations of the specific bacterial species to the given antibiotic, (2) in vitro conditions required for antibiotic induced alterations, (3) the mechanisms of action; (4) immune responses to the abnormal forms, and (5) relationship between abnormal structure and the inhibition of bacterial replication. This review provides the reader with a description and the significance of current research in the above areas which together comprise the growing field of subinhibitory concentrations of antibiotics.