Abstract
Molecular biology is omnipresent in medical biology especially in microbiology. Many papers report studies on its importance in diagnosis, prognosis, therapeutic field, epidemiology, natural (or not) biological risks alike. The important sum of reports on this subject does not always bring an obvious answer to the part that molecular biology could play in a microbiology laboratory either public or private. This article summarizes the contributions of this specialized field in microbiology and brings some questions on its contribution. Is molecular biology a real progress in microbiology? What are the main indications of molecular biology today in this field? According to the infectious particle, the answers are not always simple. They can be obvious in some cases (for instance, hepatitis C) or less obvious in other cases (tuberculosis for instance). In this article divided in two parts, the first one report an introduction to molecular biology in microbiology and the following second part will deal with the main applications in microbiology.