Anaerococcus murdochii is a bacterial species commonly found in various environments, including the human body. While often coexisting harmlessly as part of the body’s natural microbial community, it can sometimes be associated with infections. Understanding this bacterium’s nature and its potential to cause disease is important for recognizing and addressing related health concerns.
What Anaerococcus murdochii Is
Anaerococcus murdochii is classified as a Gram-positive, anaerobic coccus, meaning its cells are spherical, retain a purple stain in the Gram staining procedure, and thrive in oxygen-lacking environments. These non-motile, non-spore-forming cells typically measure between 0.6 and 0.9 micrometers and often appear in pairs, tetrads, short chains, or irregular clusters. The bacterium was named in honor of D.A. Murdoch, who significantly advanced the knowledge of anaerobic cocci.
This bacterium is a part of the normal human microbiome, commonly residing on the skin, in the gastrointestinal tract, and within the female genitourinary tract. It belongs to the genus Anaerococcus, a group of Gram-Positive Anaerobic Cocci (GPAC) found in the human body. Anaerococcus murdochii grows best at 37°C in an oxygen-free atmosphere.
The bacterium can ferment carbohydrates weakly, producing weak acids as metabolic byproducts. Its primary energy sources are peptones and amino acids. While generally a harmless inhabitant, its presence as part of the normal flora means it can sometimes cause infection under specific conditions.
Infections It Causes
Anaerococcus murdochii is frequently identified in deep-seated anaerobic infections. It is often isolated from skin and soft tissue infections, including abscesses and cellulitis, particularly where reduced oxygen tension or tissue damage creates a suitable environment. The bacterium has also been found in bone and joint infections, as well as cases of bacteremia.
This bacterium can transition from a harmless commensal to a pathogen when conditions in the body change, such as when physical barriers like skin or mucous membranes are disrupted. Compromised immune systems or underlying conditions like diabetes mellitus can also predispose individuals to infections involving Anaerococcus murdochii. These infections are often polymicrobial, which can complicate the clinical picture and treatment.
The bacterium possesses mechanisms that contribute to its ability to cause infections, including the production of toxins and enzymes like lipases, proteases, hyaluronidases, and collagenases. It can also form biofilms, communities of bacteria encased in a protective matrix, potentially enhancing its ability to adhere to tissues and resist antimicrobial agents. The clinical presentation of these infections can vary depending on the site and severity, commonly involving localized pain, swelling, pus formation, and tissue necrosis.
Identifying and Managing Infections
Identifying infections caused by Anaerococcus murdochii presents challenges due to its anaerobic nature. Clinical samples must be collected and transported under anaerobic conditions. Laboratories use selective media and incubate cultures in anaerobic chambers for optimal growth, which can take 48 to 72 hours for visible colonies. Phenotypic identification relies on biochemical tests.
Molecular methods offer precise identification by detecting the bacterium’s unique genetic signature. MALDI-TOF MS is another reliable tool for identifying anaerobic isolates, known for its accuracy and speed. This method analyzes the protein spectrum of the bacteria for rapid identification.
Management of Anaerococcus murdochii infections primarily involves antibiotic therapy. However, the bacterium can show variable susceptibility or resistance to certain antibiotics, which underscores the importance of antimicrobial susceptibility testing. This testing guides clinicians in selecting the most effective antibiotic regimen for a specific infection. Susceptibility patterns can differ between strains. Untreated infections can lead to complications such as tissue damage and systemic spread, highlighting the need for timely and appropriate medical intervention.