This is the first study to use meta-analysis and a systematic review to determine the prevalence of VRE in poultry in Malaysia, to the best of current knowledge. The pooled prevalence in this study is based on a thorough analysis of data from scientific publications on the prevalence of VRE in poultry in Malaysia published between 2001 and 2020. A meta-analysis was performed on 17 studies. The literature reviewed was heterogeneous, as expected, because the review included VRE reports from various regions, different study years, a variety of isolate sources and different methods for VRE detection. As a result, a random effect size model was used. This study’s high heterogeneity could be attributed to small-study effects and publication bias, because smaller studies sometimes show unusual, and often larger, treatment effects when compared to larger ones.

A small study with a larger-than-average impact is more likely to meet the statistical significance criterion, which may lead to an overestimation of true therapeutic effects. The assessment of publication bias is critical in meta-analysis. This is due to the fact that not all research findings are published, particularly those that are deemed unfavorable to a developed protocol or product, or those that would elicit only a minor amount of interest. Thus, studies that report relatively significant treatment effects are more likely to be submitted and/or approved for publication than studies that report more modest treatment effects. Current meta-analysis revealed a high level of variability, implying that the observed variability was compensated for by factors other than chance. The majority of the variables examined in these studies resulted in the observed heterogeneity. Similarly, studies with isolates from poultry products and chicken, studies with AST cards as detection methods and a study conducted in the year 2000 were not indicators of study heterogeneity.

There were no previous studies on meta-analysis to compare the prevalence of VRE in poultry in Malaysia, as this is the first study to analyze the prevalence of VRE in poultry in Malaysia. However, Wada et al. [1] reported a VRE pooled prevalence of 25% in Malaysia. In this current review, studies reporting the highest prevalence of VRE in poultry in Malaysia were mostly carried out in the Central region of the country. Most universities and research facilities such as the Department of Veterinary Services located in Putrajaya and National Pharmaceuticals Regulatory Agency (NPRA) which specializes in the surveillance of pathogens and regulations of drugs are located in the Central region of the country and this could be the reason why most of the studies were reported from that region. The density of poultry production in these regions could also be a factor. It is important that other regions are actively involved in the surveillance of Enterococcus and other pathogens, as this will help project the true estimate of the prevalence of VRE in poultry in Malaysia. Further, more up-to-date research is required as the most recent study reporting the prevalence of VRE in poultry was carried out in 2018 and published in 2020. It is either because the occurrence of resistant Enterococcus has reduced as a result of the ban on avoparcin or there is simply not enough surveillance going on to ascertain an actual estimate. Avoparcin and vancomycin were banned in Malaysia since 2013 by the National Pharmaceuticals Regulatory Agency (NPRA) and the Department of Veterinary Services (DVS) [4].

It is not surprising that most of the studies reported the isolation of VRE from chickens. Malaysians were expected to consume 48.7 kg of poultry meat per person in 2021, according to projections. This places Malaysia among the world’s top consumers of poultry meat [4]. In addition, the disc diffusion and agar dilution were the two most utilized VRE detection methods in poultry in Malaysia. Eight studies utilized the disc diffusion method, which has been reported to be straightforward and functional, with a well-standardized design, and it has the ability to provide categorical data that are simply understood by all practitioners, as well as the ability to choose from a variety of discs to test [19]. The lack of mechanization or automation of the disc test is one of its drawbacks. Only one study utilized PCR in the detection of VRE. For the detection and characterization of distinct VRE species, PCR is a quicker and more sensitive approach [20]. Finally, E. faecalis was the most isolated species of VRE in poultry in Malaysia from current analysis. The most frequent species capable of producing illness and creating an antibiotic resistance concern are E. faecalis and E. faecium, with E. faecalis accounting for the bulk of infections [21] E. faecalis is now recognized as a severe source of both hospital- and community-acquired urinary tract infections (UTIs), which can result in serious, life-threatening consequences such as bacteremia [22].

The use of antibiotics in animal husbandry varies by location and country. Antibiotics are sold in significantly larger quantities in low- and middle-income nations than they are in high-income countries [23]. As a region of fast-developing and integrated economies, Southeast Asia (SEA) is considered a hotspot location for antimicrobial resistance (AMR) [24]. Low- and middle-income nations utilized more antibiotics classified as medically important when compared to high-income countries [23]. The presence of veterinary drug traces in food samples confirmed this, indicating that violation rates in underdeveloped nations were higher than in developed nations [25].

SEA countries have had fast growth in the aquaculture and poultry production sectors in recent decades, accounting for a relatively large proportion of the worldwide veterinary antibiotic market [24]. Antibiotic management and therapy has become one of the most effective ways for these countries to avoid uncontrolled epidemic infections that could threaten their economies [24].