Bacteroides melaninogenicus

Bacteroides melaninogenicus

Bacteroides melaninogenicus is a species of Gram-negative anaerobic bacteria that is part of the normal flora of the human body, particularly in the oral cavity, gastrointestinal tract, and genitourinary tract. It is known for its role in various infections, especially those involving the oral cavity and respiratory tract.

Characteristics

Bacteroides melaninogenicus is a non-spore-forming, rod-shaped bacterium. It is characterized by its ability to produce black pigment when grown on blood agar, which is due to the production of melanin-like compounds. This pigmentation is a distinguishing feature that aids in its identification in the laboratory.

The bacterium is obligately anaerobic, meaning it thrives in environments devoid of oxygen. It is also part of the Bacteroidetes phylum, which includes other important anaerobic bacteria.

Pathogenicity

While Bacteroides melaninogenicus is typically a commensal organism, it can become pathogenic under certain conditions. It is often involved in polymicrobial infections, where it acts synergistically with other bacteria to cause disease. Common infections associated with Bacteroides melaninogenicus include:

• Periodontal disease
• Lung abscesses
• Aspiration pneumonia
• Empyema

The bacterium's ability to produce enzymes and toxins contributes to its pathogenic potential. It can degrade host tissues and evade the immune response, leading to persistent infections.

Antibiotic Resistance

Bacteroides melaninogenicus, like other members of the Bacteroides genus, has shown resistance to several antibiotics, including penicillin. This resistance is often mediated by the production of beta-lactamase enzymes, which can inactivate beta-lactam antibiotics. Treatment of infections caused by Bacteroides melaninogenicus typically involves the use of antibiotics such as metronidazole or clindamycin, which are effective against anaerobic bacteria.

Laboratory Identification

In the laboratory, Bacteroides melaninogenicus can be identified by its characteristic black pigmentation on blood agar. Additional tests, such as biochemical assays and molecular techniques, can confirm its identity. The use of anaerobic culture conditions is essential for its growth and isolation.

Also see

• Bacteroides fragilis
• Anaerobic bacteria
• Periodontal disease
• Antibiotic resistance