Vancomycin-Resistant Enterococcus: Issues in Human Health, Animal Health, Resistant Mechanisms and the Malaysian Paradox

Abstract

E nterococcus occur naturally in the surroundings and are an important constituents of the gut microbes in humans and animals (van Schaik and Willems, 2010; Boehm and Sassoubre, 2014). Enterococcus species detected till date are over 50 (Bonacina et al., 2016; Guzman et al., 2016). In human guts, Enterococcus faecalis occur mostly followed by E. faecium while in livestock, E. faecium is the major species followed by E. faecalis, E. cecorum and sometimes E. hirae (Klein, 2003; Guzman et al., 2016). Urinary tract infections, inflammation of the endocardium, and blood infection are linked to Enterococci and these conditions are particularly worse in immunocompromised individuals (Lebreton et al., 2014; Neelakanta et al., 2015). Nosocomial and drug-resistant infections are largely caused by E. faecium and E. faecalis and these pathogens are largely accountable for human vancomycin-resistant enterococci (VRE) infections (van Schaik and Willems, 2010; Leb-reton et al., 2013). The spotlight was beamed on Enterococci as a significant hospital-acquired microbe in regard to their innate resistance to various antibiotics, the rate at which they become highly infectious and the factors responsible for their multidrug resistance (Balli et al., 2014; Bourgeois-Nicolaos et al., 2014; Kristich et al., 2014). Epidemiological reports have continued to implicate VRE in regards to its effect on health, the economy and continuous infection in humans (Byappanahalli et al., 2012; Shaghaghian et al., 2012) following to their earliest documentation in the 80s (Leclercq et al., 1988; Uttley et al., 1988). Though VRE is hardly seen in pets, they rarely cause infection in animals (Willems et al., 2011). Studies have suggested that Enterococcus resistant to vancomycin act as a reservoir and source of resistant genes. This article, therefore, discusses and reviews VRE, its phenotypic and genotypic characteristics, antimicrobial resistance, virulence factors and zoonotic potential. Finally, it sheds review Article Abstract | Enterococcus is a major constituent of the intestinal flora and environment. They are a hardy organism and can survive harsh prevailing environmental factors and hosts. Over time, the constant and heavy usage of antibiotics like vancomycin in treating infection caused by them has resulted in their development of resistance and virulent characteristics. VRE infections in animals are uncommon, and even so in pets. The reverse is, however, the case with human VRE infection. VRE are of great importance in public health, animal and medical health. The adaptability and complexity of the VRE genes have resulted in the appearance of resistant species in a wide range of environment and hosts which will invariably allow the host and environment to act as a reservoir. This article, therefore, discusses and reviews VRE, its phenotypic and genotypic characteristics, antimicrobial resistance, virulence factors and zoonotic potential. Finally, it sheds light on the situation of VRE in Malaysia. This would be the first review to look at V...

Genetic mechanisms and correlated risk factors of antimicrobial-resistant ESKAPEE pathogens isolated in a tertiary hospital in Malaysia

“…All three hospitals, including UMMC in this study, are located in Klang Valley within close proximity of each other. Previous studies reported a greater prevalence of the van A gene among Malaysian VRE strains isolated from various sources, including humans, farmed animals, and even within the natural environment [ 18 , 19 ]. However, we observed that the van B gene occurred more frequently in the VRE strains identified in this study.…”

Low Occurrence of Virulence Determinants in Vancomycin-Resistant Enterococcus from Clinical Samples in Southwest Nigeria

“…The virulence factors of enterococci play a major role in the pathogenicity of enterococci and could be explained not only by the presence of virulence determinants; antibiotic resistance genes play an important role in the pathogenicity of enterococcal strains (15,16). In vivo and on medical devices biofilm formation aids disease development as it boosts the persistence infections and reduces antimicrobial activity (17).…”

Prevalence of Vancomycin-Resistant Enterococcus (VRE) in Poultry in Malaysia: The First Meta-Analysis and Systematic Review

“…Human antimicrobial use, as well as their use as growth promoters in the livestock industry, were thought to have resulted in the emergence of enterococcal-resistant strains. A good example is the use of avoparcin as a feed additive to promote livestock growth [ 3 ].…”