Rothia kristinae: Introduction, Pathogenicity, Lab Diagnosis, Treatment

Rothia kristinae: Introduction, Pathogenicity, Lab Diagnosis, Treatment, Prevention, and Keynotes

Introduction & Taxonomy

Rothia kristinae is a Gram-positive bacterium increasingly recognized as an emerging opportunistic pathogen. While typically a harmless commensal of human skin and mucosal surfaces, it can cause severe systemic infections, particularly in individuals with compromised immune systems or indwelling medical devices.

Classification: A member of the Micrococcaceae family, this organism was originally classified as Micrococcus kristinae (1974), moved to Kocuria (1995), and finally reclassified as Rothia in 2018 based on genomic data.
Habitat: It colonizes human skin, the oropharynx, and the upper respiratory tract.

Pathogenicity & Clinical Manifestations

Risk Factors: Primarily affects immunocompromised patients, such as those with cancer or indwelling devices.
Clinical Picture: Causes infections, including catheter-related bacteremia (~36% of cases) and endocarditis (~13.7%).
Virulence: Known to form biofilms on medical devices.

Laboratory Diagnosis of Rothia kristinae

Identification: Appears as Gram-positive, non-motile cocci in pairs or clusters. Grows on blood agar within 48 hours, forming pale to orange colonies.
Biochemical Profile: Catalase-positive, but oxidase and coagulase-negative.
Distinction: Often distinguished from Staphylococcusby susceptibility to bacitracin and resistance to lysostaphin.
Gold Standard: Identification is best achieved via 16S rRNA sequencing or MALDI-TOF MS.

Treatment & Prevention

Treatment: Vancomycin is typically effective, along with linezolid or rifampicin, though resistance to certain drugs, such as clindamycin, can occur.
Management: Successful treatment often requires removing infected catheters.
Prevention: Adherence to infection control protocols (e.g., CLABSI bundles) is critical.

Keynotes on Rothia kristinae

R. kristinaes should not be dismissed as a contaminant, particularly in recurring blood cultures.
Commonly misidentified in labs as Coagulase-Negative Staphylococci (CoNS).

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