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Molecular identification of Gemella species from three patients with endocarditis
1Unité des Rickettsies, CNRS UPRESA 6020, Faculté de Médecine, Université de la Méditerrannée, Marseille, France.
Abstract:
Gemella morbillorum and Gemella haemolysans are opportunistic pathogens which cause endocarditis and other severe infections. We report on three patients with endocarditis, one with endocarditis caused by G. haemolysans and two with endocarditis caused by G. morbillorum. The paucity of reports concerning these bacteria is probably related to the difficulties associated with their identification. For example, one of the strains reported in this study was originally sent to our laboratory with a preliminary characterization as a short "gram-negative" coccobacillus, highlighting the specific problem associated with Gram staining of these bacteria. The usefulness of 16S rRNA gene amplification, partial sequencing, and comparison of the nucleotide sequence to those in databases when standard phenotypic identification schemes are not helpful is emphasized. We also suggest that the use of simple tests, such as testing susceptibility to vancomycin for gram-negative bacteria and colistin for gram-positive bacteria, could prevent misinterpretation of Gram staining in gram-variable bacteria such as Gemella spp.
Insights
Gemella morbillorum and Gemella haemolysans can cause severe infections like endocarditis. Accurate identification is challenging, but molecular methods and specific antibiotic susceptibility tests can aid diagnosis.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Diagnostics
Background:
- Gemella morbillorum and Gemella haemolysans are opportunistic pathogens.
- These bacteria are known to cause severe infections, including endocarditis.
- Previous reports on these pathogens are limited, potentially due to identification challenges.
Observation:
- This study reports on three patients with endocarditis: one caused by G. haemolysans and two by G. morbillorum.
- A key challenge in identification is the difficulty in Gram staining, with one isolate initially mischaracterized as a Gram-negative coccobacillus.
- Standard phenotypic identification methods may be insufficient for accurate classification.
Findings:
- 16S rRNA gene amplification, sequencing, and database comparison are valuable tools when phenotypic identification fails.
- Susceptibility testing to vancomycin (for Gram-negative) and colistin (for Gram-positive) can help prevent misinterpretation of Gram-variable bacteria like Gemella spp.
Implications:
- Improved diagnostic strategies are needed for Gemella species to ensure timely and appropriate treatment.
- Molecular techniques and targeted biochemical tests can enhance the accurate identification of these difficult-to-classify bacteria.
- Enhanced diagnostic accuracy for Gemella infections can lead to better patient outcomes and infection control.