A method of biological analysis of biological samples, comprising the phases of: a) introducing a biological sample to be analyzed in a container containing a growth medium; b) incubating the container for a first incubation time interval; c) following said first incubation time interval, analyzing the atmosphere in said container and comparing the atmosphere in said container with a maximum value and a minimum value of carbon dioxide concentration, and: - if the atmosphere contains a carbon dioxide quantity lower than the minimum value, classifying the sample as not containing a pathologically relevant bacterial load, such that the sample is not subjected to an analysis in order to detect the microorganisms present; - if the atmosphere contains a carbon dioxide quantity greater than the maximum value, classifying the sample as containing a pathologically relevant bacterial load and subjecting said sample to an analysis in order to detect the microorganisms present; - if the atmosphere contains a carbon dioxide quantity comprised between the maximum value and the minimum value, maintaining said biological sample in incubation for a second incubation time interval; d) before said second incubation time interval, injecting oxygen in said container; e) at the end of said second incubation time interval, analyzing the atmosphere in said container and classifying the biological sample as containing a pathologically relevant bacterial load or not containing a pathologically relevant bacterial load depending upon whether the carbon dioxide content in the atmosphere of the container is greater or lower than a threshold value. a) introducing a biological sample to be analyzed in a container containing a growth medium; b) incubating the container for a first incubation time interval; c) following said first incubation time interval, analyzing the atmosphere in said container and comparing the atmosphere in said container with a maximum value and a minimum value of carbon dioxide concentration, and: - if the atmosphere contains a carbon dioxide quantity lower than the minimum value, classifying the sample as not containing a pathologically relevant bacterial load, such that the sample is not subjected to an analysis in order to detect the microorganisms present; - if the atmosphere contains a carbon dioxide quantity greater than the maximum value, classifying the sample as containing a pathologically relevant bacterial load and subjecting said sample to an analysis in order to detect the microorganisms present; - if the atmosphere contains a carbon dioxide quantity comprised between the maximum value and the minimum value, maintaining said biological sample in incubation for a second incubation time interval; - if the atmosphere contains a carbon dioxide quantity lower than the minimum value, classifying the sample as not containing a pathologically relevant bacterial load, such that the sample is not subjected to an analysis in order to detect the microorganisms present; - if the atmosphere contains a carbon dioxide quantity greater than the maximum value, classifying the sample as containing a pathologically relevant bacterial load and subjecting said sample to an analysis in order to detect the microorganisms present; - if the atmosphere contains a carbon dioxide quantity comprised between the maximum value and the minimum value, maintaining said biological sample in incubation for a second incubation time interval; d) before said second incubation time interval, injecting oxygen in said container; e) at the end of said second incubation time interval, analyzing the atmosphere in said container and classifying the biological sample as containing a pathologically relevant bacterial load or not containing a pathologically relevant bacterial load depending upon whether the carbon dioxide content in the atmosphere of the container is greater or lower than a threshold value.