If an infected area is to be explored, preoperative aspirate of fluid accumulation and especially intraoperative tissue sampling from several potentially infected sites, prior to the start of any antibiotics, provide the best material for detecting the infecting microorganism(s). At least 5 specimens should be taken for microbiology testing. One sample should be sent for histopathology. Both aerobic and anaerobic cultures should be undertaken. PCR, if available will speed up, and make more reliable, the characterization
of the organisms. If hardware is removed, this can be cultured as well preferably after sonication.
Histological investigation can reveal a bacterial etiology, even if the microbiological tests are negative. Superficial wound swabs should be avoided because of low sensitivity and frequent contamination by surface organisms. Ideally, prior to tissue sampling for culture, it is important to discontinue any antibiotic therapy for at least a week.