Sinuses are hollow, air-filled cavities in the human skull. They're connected to the nasal passages and help insulate the skull and amplify the voice. Anaerobic sinus infections are the inflammation of sinuses caused by anaerobic bacteria---those that live in the absence of oxygen. They affect about 30 percent of patients with chronic sinus infections and can last for more than eight weeks. Common symptoms include pressure in the nose, eyes and cheek, along with headaches, coughs, fever and bad breath.
Causes
Anaerobic sinus infections occur in patients with pre-existing conditions such as allergies, upper respiratory tract infections or anaerobic dental infections. These conditions lead to thickening of the sinus lining, creating an environment favorable for the multiplication of anaerobic bacteria. Peptostreptococcus sp., Fusobacterium necrophorum, Bacteroids sp. and Prevotella sp. are the most common anaerobic bacteria associated with sinus infections. Sinus infections caused by anaerobic bacteria can spread further and cause severe infections of the brain, eye and ear, and can also lead to formation of clots in the sinuses. This condition is known as sinus thrombosis, and it can lead to coma and even death.
Risk Factors
Anaerobic bacteria are part of the normal flora of the mouth and the throat. Reduced immunity, antibiotic therapy and conditions that lower blood supply, such as tumors, surgery and localized swelling, can increase a person's susceptibility to these infections. Infection of the sinuses with aerobic bacteria---those that live in presence of oxygen---can also create conditions that promote the growth of anaerobes.
Diagnosis
Preliminary diagnosis of an anaerobic sinus infection involves visual inspection of the nasal passages. Techniques like endoscopy or magnetic resonance imaging may be done to see the sinuses and the nasal areas. Treatments are usually prescribed based on the results of these tests. If the patient doesn't respond to the medications, the specific anaerobe responsible for the infection needs to be identified. In such cases, a saline "wash-out" or a pus aspiration from the sinus is collected and transported to the laboratory in an anaerobic jar. Procedures like Gram stain, cultures and antimicrobial assays are done to identify the microorganism and to determine the antibiotics effective against it.
Treatment
Penicillin G is the drug of choice against sinus infections caused by anaerobic bacteria such as Peptostreptococcus sp. and Fusobacterium sp. However, some Bacteroids sp. and Prevotella sp. may be resistant to penicillin. Other antibiotics, such as cephalosporins, chloramphenicol, clindamycin or vancomycin, can be used to treat these cases.
Prevention
Improving immunity by avoiding stress and by consuming food rich in antioxidants is key in minimizing the likelihood of an anaerobic sinus infection. Avoiding allergens can prevent blockage of nasal passages and multiplication of anaerobic bacteria in the sinuses. Maintaining a healthy oral hygiene can also help prevent anaerobic sinus infections.
References
- "Medical Microbiology"; Patrick R. Murray, Ken S. Rosenthal, George S. Kobayashi, Michael A. Pfaller; 2005
- Clinical Microbiology Reviews: Human Infection with Fusobacterium necrophorum (Necrobacillosis), with a Focus on Lemierre's Syndrome
- "Journal of Medical Microbiology"; Microbiology of Chronic Maxillary Sinusitis; I. Brook, E. H. Frazier and P. A. Foote; May 1997
