Isolation and detection of bacterial species on mitis salivarius bacitracin agar from the plaque samples of caries active children

• Published in: Journal of the Indian Society of Pedodontics and Preventive Dentistry Vol. 42; no. 1; pp. 15 - 21
• Main Authors: Bansal, Kalpana, Shamoo, Azeema, Atif, Mohammad, Batra, Priyam, Chaudhry, Rama
• Format: Journal Article
• Language: English
• Published: Chandigarh Medknow Publications & Media Pvt. Ltd 2024; Wolters Kluwer Medknow Publications
• Subjects: anaerobic culture; Bacitracin; Bacteria; Children; Colonies; Dental caries; Dental plaque; Epidemiology; Ionization; Mass spectroscopy; matrix-assisted laser desorption ionization-time of flight; mitis-salivarius agar medium; Mouthwashes; nonstreptococcal mutans; Pediatrics; Plant extracts; Selective media; Species; streptococcus mutans
• ISSN: 0970-4388; 1998-3905
• DOI: 10.4103/jisppd.jisppd_17_24

Background: In cariology studies, mitis-salivarius-bacitracin (MSB) agar has been commonly considered as the selective medium for Streptococcus mutans growth. The present study was the part of a funded project (a noninferiority randomized controlled trial) which compared the efficacy of a plant extract-based mouth rinse with that of a fluoride mouth rinse on the S. mutans counts of the children. Aim: This study aimed to identify the frequency of detection of S. mutans and nonstreptococcal bacterial species from the dental plaque of caries active children using a combined technique of anaerobic culture and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Settings and Methods: Caries-active children (8–12 years old) were enrolled from a pediatric dental outpatient department at a tertiary care hospital. From each participant, dental plaque samples were collected from carious surfaces under sterilized conditions and then subjected to anaerobic culture. After 48 h of incubation, the bacterial colonies were isolated by sub-culture and identified by the MALDI-TOF. Results: In all, 13 different bacterial species were isolated from the MSB agar medium. Other than S. mutans species, colonies of bacterial species such as Veillonella dispar, Streptococcus anginosus , Veillonella parvula , and Streptococcus gordonii were also frequently observed from the medium . Conclusions: The study concluded that several bacterial strains, both streptococcal and nonstreptococcal, could be isolated from the MSB agar medium; hence, this medium should no longer be considered selective medium for the culture of S. mutans in clinical and epidemiological studies.