Genetic Trends In A Population Evolving Antibiotic Resistance

Genetic Trends In A Population Evolving Antibiotic Resistance

The development of bacteria! Resistance to antibiotics is one of the best documented cases of contemporary bio logical evolution. The huge consumption (more than one tall per day in some European countries) of this type of compound ? able to inhibit bacterial growth at very low concentrations ? both in man and 311lmills ? has resulted in the emergence and spread of a vast amount of antibiotic resistance determinants among bacterial populations ? thus creating a critical public health problem (Fig. 1). Antibiotics are among the very few drugs that cure ? rather than just reduce the symptoms of disease ? and much of the progress in modern medicine (as intensive rare ? advanced surgery ? cancer chemotherapy or organ transplantation) has been developed under the protective umbrella of antibiotics. The danger of a return to a pre-antibiotic era is now becoming a serious threat ? particularly considering that no novel chemical class of antibiotics has been introduced in the past 20 years' despite intensive research ill the pharmaceutical industry. That has offered to the microbial world the unique opportunity to evolutionarily refine and spread their resistance strategies against widely used conventional antimicrobial agents.

The mechanisms by which bacteria have become resistant to the different families of antibiotic agents. The origin of these resistance mechanisms remains an open evolutionary question'. Genes currently involved in antibiotic resistance have probably evolved for other purposes than antibiotic resistance. In this view ? resistance can be considered as a chance product ? deterrntned by the interaction of an antibiotic and a particular genotype. This is not incompatible with the idea of a gradual modification of some genes of pre-existing cellular machinery to become resistance genes. Possession of some 'housekeeping' genes may be ...