Enterococcus raffinosus

Enterococcus raffinosus is a Gram-positive bacterium that belongs to the genus Enterococcus. It is part of the normal gastrointestinal flora in humans and animals but can also be an opportunistic pathogen.

Morphology and Physiology

Enterococcus raffinosus is a coccoid bacterium that typically appears in pairs or short chains. It is non-motile and does not form spores. The bacterium is facultatively anaerobic, meaning it can grow in both the presence and absence of oxygen. It is catalase-negative but can produce hydrogen peroxide in the presence of heme.

Biochemical Characteristics

Enterococcus raffinosus can ferment a variety of carbohydrates, including raffinose, from which it derives its name. It is also capable of hydrolyzing esculin in the presence of bile, a characteristic that is used in laboratory identification. The bacterium is tolerant to high concentrations of sodium chloride and can grow in the presence of 6.5% NaCl.

Pathogenicity

While Enterococcus raffinosus is generally considered a commensal organism, it can cause infections, particularly in immunocompromised individuals. It has been associated with urinary tract infections, bacteremia, endocarditis, and intra-abdominal infections. The pathogenicity of E. raffinosus is similar to other enterococci, involving the ability to adhere to host tissues and form biofilms.

Antibiotic Resistance

Enterococcus raffinosus has intrinsic resistance to several antibiotics, including cephalosporins and low levels of aminoglycosides. It may also acquire resistance to other antibiotics, such as vancomycin, through horizontal gene transfer. The presence of vancomycin-resistant enterococci (VRE) is a significant concern in healthcare settings.

Clinical Significance

In clinical settings, Enterococcus raffinosus is identified using a combination of phenotypic and genotypic methods. It is important to accurately identify this species due to its potential for antibiotic resistance and its role in nosocomial infections. Treatment of infections caused by E. raffinosus may require the use of combination antibiotic therapy, especially in cases of multidrug-resistant strains.

Laboratory Identification

Laboratory identification of Enterococcus raffinosus involves culture on selective media, such as bile esculin agar, and biochemical testing for carbohydrate fermentation patterns. Molecular methods, such as polymerase chain reaction (PCR) and 16S rRNA sequencing, can provide definitive identification.

Prevention and Control

Preventing infections caused by Enterococcus raffinosus involves standard infection control practices, including hand hygiene and environmental cleaning. In healthcare settings, monitoring and controlling the spread of antibiotic-resistant strains is crucial.

See Also

• Enterococcus
• Vancomycin-resistant enterococcus
• Nosocomial infection

External Links

• [CDC - Enterococcus]
• [NIH - Enterococcus Research]