Abstract
This study aimed to isolate and characterize bacteriophages, as a biocontrol agent, against certain antibiotic-resistant bacteria causing dental caries. Here, two dental caries-causing bacteria S. aureus and E. faecalis were isolated and characterized biochemically using the automated VITEK® 2 system. Antibiotic sensitivity pattern of the isolated dental caries bacteria was assessed against selection of antibiotics. The two isolates showed resistance against most of the tested antibiotics. To overcome this problem, two lytic phages vB_SauM-EG-AE3 and vB_EfaP-EF01 were isolated, identified, and applied to control the growth of S. aureus and E. faecalis, respectively. Phages were identified morphologically using TEM and showed that vB_SauM-EG-AE3 phage is related to Myoviridae and vB_EfaP-EF01 phage belongs to Podoviridae. The two phages exhibited high lytic activity, high stability, and a narrow host range. The one-step growth curve of phages showed burst sizes of 78.87 and 113.55 PFU/cell with latent periods of 25 and 30 minutes for S. aureus phage and E. faecalis phage respectively. In addition, the two phages showed different structural protein profiles and exhibited different patterns using different restriction enzymes. The genome sizes were estimated to be 13.30 Kb and 15.60 Kb for phages vB_SauM-EGAE3, vB_EfaP-EGAE1, respectively. Complete inhibition of bacterial growth was achieved using phages with MOIs of 103, 102 and 10 after 1, 3, 5, and 24 h of incubation at 37°C. Hence, this study indicates that the isolated bacteriophages are promising biocontrol agents that could challenge antibiotic-resistant dental caries bacteria to announce new successful alternatives to antibiotics.
Highlights
Enterococcus is a genus of Gram-positive, non-spore-forming bacteria commonly found in the oral cavity, gastrointestinal tract, and vagina[1]
Two pathogenic bacteria, S. aureus and E. faecalis, which are related to dental caries, were isolated previously from infected patients with dental decays and cavities, which agrees with Ohara-Nemoto et al.[39] and Wang et al.[40]
Health concerns related to dental diseases have been exacerbated by antibiotic-resistant S. aureus and E. faecalis
Summary
Enterococcus is a genus of Gram-positive, non-spore-forming bacteria commonly found in the oral cavity, gastrointestinal tract, and vagina[1]. Emergence of Enterococcus as human pathogens due to the presence of virulence factors such as adhesive production and aggregation compounds, or biogenic amine production in fermented foods[3] and they resist different measures of disinfection and create a biofilm[4]. E. faecalis can act as an opportunistic pathogen that causes bacteremia, meningitis, endocarditis, or urinary tract and wound infection[5,6]. It has several survival mechanisms for living in unfavorable environments, such as grow in a low-oxygen environment at high pH, a broad range of temperatures between 10°C and 60°C and high salinity or a poor nutritional environment[7]. The therapeutic challenge of multi-drug resistant enterococci (MDR) strains with substantial resistance to two or more antibiotics, often including, though not limited to, vancomycin, has brought their role to a sharper focus[10]
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