Prevotella species – the most prevalent black-pigmented anaerobic bacteria among oropharyngeal isolates obtained from a sample of healthy young adults

DOI: https://doi.org/10.25241/stomaeduj.2020.7(2).art.1



Introduction The black-pigmented Prevotella – Porphyromonas group comprises members of the normal flora of the oral cavity, oropharyngeal, intestinal and genitourinary tract, but may be associated with various infections too. The purpose of this study was to identify the species of this anaerobic group which frequently colonize the oropharynx in clinically healthy young adults.
Methodology The microbiological investigation was carried out on a strain collection of 93 dark-pigmented anaerobic isolates originated from the oropharynx of healthy dental students, at the Department of Microbiology, Faculty of Dental Medicine, “Carol Davila” University of Medicine and Pharmacy – Bucharest, Romania. All isolates of Gram-negative bacilli were identified at the genus and species level by conventional methods, MASTRING ID (MAST Group Ltd., U.K.) and Rapid ID 32 A system (BioMérieux, France), while the isolates of anaerobic cocci were tested only by MASTRING ID.
Results The microscopy of the Gram-stained smears and the results of the MASTRING ID test performed with the 93 black-pigmented anaerobic isolates indicated that 77 strains were Gram-negative bacilli and/or coccobacilli, while 16 strains were Gram-positive cocci. The identification of the Gram-negative bacilli at the species level concluded that 57 strains belonged to Prevotella denticola, 18 strains to Prevotella melaninogenica and 2 strains to Prevotella intermedia.
Conclusion P. denticola and P. melaninogenica might be considered the main species of the black-pigmented Prevotella-Porphyromonas group which colonize the oropharynx in healthy young adults. These species are usually beta-lactamase producers and their high rate of oropharyngeal colonization should be considered when antibiotics are needed in oral infections therapy.

Oropharynx, Microbiota, Anaerobes, Black-Pigmented Bacteria, Prevotella.