Mixed anaerobic infections

[Jason Yan]

Anaerobes can infect normal hosts and hosts with compromised resistance or damaged tissues. Mixed anaerobic infections can include both single anaerobic species or multiple anaerobic species with any number of nonanaerobic isolates. Symptoms depend on site of infection. Diagnosis is clinical combined with Gram stain and anaerobic cultures. Treatment is with antibiotics and surgical drainage and debridement.
(See also Overview of Anaerobic Bacteria.)
Hundreds of species of nonsporulating anaerobes are part of the normal flora of the skin, mouth, gastrointestinal tract, and vagina. If this commensal relationship is disrupted (eg, by surgery, other trauma, poor blood supply, or tissue necrosis), a few of these species together can cause infections with high morbidity and mortality. After becoming established in a primary site, infection can spread locally and hematogenously to distant sites.
Because aerobic and anaerobic bacteria are frequently present in the same infected site, appropriate procedures for isolation and culture are necessary to keep from overlooking the anaerobes.
Anaerobes can be the main cause of infection in the following:

The pleural spaces and lungs
Intra-abdominal, gynecologic, central nervous system, upper respiratory tract, and cutaneous diseases
Bacteremia