Microbiological cultures provide essential information to guide the antibiotic therapy. However, their results might be misleading for physicians and drive useless treatment, sometimes harmful for patients. Recommendations highlight the importance of clinical signs in order to take into account the pre-test probability when interpreting the results. This combination will improve the predictive value of microbiological tests. The sampling strategy is also important to avoid an overuse of these tests but also misleading results through a reduction of contaminants.