A microbiological examination involves collecting a sample of abnormal nipple discharge (such as pus or colored discharge) and culturing it on selective nutrient media for aerobic and anaerobic bacteria, and in some cases, fungi. The primary goal is to isolate and identify the microorganisms causing the infection (such as Staphylococcus aureus, Streptococcus, or Escherichia coli). The examination also includes performing an antibiogram (antibiotic susceptibility test) on the isolated bacteria to guide optimal drug therapy.