Enterococcus Species in the Oral Cavity: Prevalence, Virulence Factors and Antimicrobial Susceptibility

Abstract

Enterococci are considered as transient constituent components of the oral microbiome that may cause a variety of oral and systemic infections. As there is sparse data on the oral enterococcal prevalence, we evaluated the Enterococcus spp. and their virulence attributes including antimicrobial resistance in a healthy Brazilian cohort. A total of 240 individuals in different age groups were studied (children 4–11 yrs, adolescents 12–17 yrs, young adults 18–29 yrs, adults 30–59 yrs, elderly over 60 yrs). Oral rinses were collected and isolates were identified by API 20 Strep and confirmed by 16S rDNA sequencing. E. faecalis isolates, in particular, were evaluated for virulence attributes such as their biofilm formation potential, and susceptibility to antimicrobials and an antiseptic, chlorhexidine gluconate. A total of 40 individuals (16.6%) and 10% children, 4% adolescents, 14% young adults, 30% adults, and 25% elderly carried oral enterococci. The oral enterococcal burden in adolescents was significantly lower than in the adults (p = 0.000) and elderly (p = 0.004). The proportion of carriers was higher among females (p = 0.001). E. faecalis was the most frequent isolate in all the age groups (p = 0.000), followed by E. durans and E. faecium. Whilst all the clinical isolates were able to form biofilms, only a proportion of them were able to produce lipase (92%), hemolysin (38%), and gelatinase (39%). Of all the isolates 53.8% were resistant to tetracycline, 12.3% to amoxicillin, 16.0% to ampicillin, 20.8% to chloramphenicol and 43.4% to erythromycin. None of the isolates were resistant to vancomycin. Our data suggest that in this Brazilian cohort the oral cavity may act as a significant reservoir of rather virulent and antibiotic resistant enterococci, with an increasing degree of carriage in the adults and elderly. Hence clinicians should be cognizant of this silent reservoir of virulent enterococci that may pose a particular threat of nosocomial infection.

Carriage of Multidrug Resistant Enterococcus Faecium and Enterococcus Faecalis Among Apparently Healthy Humans

“…The multiple antibiotic resistances of our isolates agree with those found in other studies (Rams et al, 2013;Komiyama et al, 2016). The recovery of MDR colonising strains of E. faecium and E. faecalis highlights the ability to these organisms to develop resistance to an array of antimicrobial drugs.…”

Enterococci: An Important Nosocomial Pathogen

“…Few studies have shown that antibiotic resistant enterococci is transmitted by food [47][48][49] but recently Vidana et al [50] have said there is no food related transmission of enterococci. Enterococci are now showing a high degree of resistance to tetracycline, chloramphenicol, erythromycin besides vancomycin pose a threat for spread of nosocomial infection particularly in patients of ICUs and on mechanical ventilators [51]. Vancomycin resistance is an independent predictor for the overall increase of hospital costs for the patient but also for the individual hospital [52].…”

Antibacterial activity of silver nanoparticles biosynthesized using Spirulina platensis microalgae extract against oral pathogens

“…Saphylococcus aureus is also an abundant Gram-positive bacteria which has a strong connection to dental implant infections (Wang and Ren, 2017). Enterococcus faecalis has been connected to oral infections, such as caries, endodontic infections, periodontitis, and peri-implantitis (Komiyama et al, 2016). Controlling these bacteria is of utmost importance in dentistry.…”

“…Streptococcus mutans and Staphylococcus aureus are key pathogens that cause infections concomitant with dental caries and dental implants (Wang and Ren, 2017). Enterococcus faecalis has been also related to oral diseases, such as caries, endodontic infections, periodontitis, and peri-implantitis (Komiyama et al, 2016). Thus, it is imperative to find ways for decreasing the bacterial burden of the oral cavity to prevent dental caries and other oral diseases (Wassel and Khattab, 2017).…”