Genetic Variability of Vancomycin-Resistant Enterococcus faecium and Enterococcus faecalis Isolates from Humans, Chickens, and Pigs in Malaysia

Abstract

Vancomycin-resistant enterococci (VRE) have been reported to be present in humans, chickens, and pigs in Malaysia. In the present study, representative samples of VRE isolated from these populations were examined for similarities and differences by using the multilocus sequence typing (MLST) method. Housekeeping genes of Enterococcus faecium (n ‫؍‬ 14) and Enterococcus faecalis (n ‫؍‬ 11) isolates were sequenced and analyzed using the MLST databases eBURST and goeBURST. We found five sequence types (STs) of E. faecium and six STs of E. faecalis existing in Malaysia. Enterococcus faecium isolates belonging to ST203, ST17, ST55, ST79, and ST29 were identified, and E. faecium ST203 was the most common among humans. The MLST profiles of E. faecium from humans in this study were similar to the globally reported nosocomial-related strain lineage belonging to clonal complex 17 (CC17). Isolates from chickens and pigs have few similarities to those from humans, except for one isolate from a chicken, which was identified as ST203. E. faecalis isolates were more diverse and were identified as ST4, ST6, ST87, ST108, ST274, and ST244, which were grouped as specific to the three hosts. E. faecalis, belonging to the high-risk CC2 and CC87, were detected among isolates from humans. In conclusion, even though one isolate from a chicken was found clonal to that of humans, the MLST analysis of E. faecium and E. faecalis supports the findings of others who suggest VRE to be predominantly host specific and that clinically important strains are found mainly among humans. The infrequent detection of a human VRE clone in a chicken may in fact suggest a reverse transmission of VRE from humans to animals.

Public Health Risks of Multiple-Drug-Resistant Enterococcus spp. in Southeast Asia

“…In 23% of urinary tract infection cases, pulsed-field gel electrophoresis patterns identical or closely related to those found in poultry were detected (65). In another study carried out in Malaysia, one vancomycin-resistant E. faecium strain isolated from a chicken was found to be clonal to that of humans (23). Treated sewage sludge, a by-product from treated sewage wastewater containing the fecal contents of animals and humans, can be used as fertilizers, which potentially pass MDR strains on to the food supply.…”

“…are a natural part of the intestinal flora of most mammals and birds (23). The livestock industries of Southeast Asia, China, and Papua New Guinea play a major role globally in terms of meat production, contributing roughly 13 to 33% of the global meat production from 1979 to 2004 (24).…”

“…The large importers of livestock, mainly cattle and pigs, are Singapore, Malaysia, and Indonesia (24). Studies carried out in Malaysia, Thailand, Vietnam, Indonesia, and other Southeast Asian countries reported MDR enterococci isolated from livestock and animal-related products (23,25). Many Southeast Asian nations, such as Malaysia, Myanmar, Indonesia, Thailand, and Vietnam, have flourishing poultry and livestock industries and are also major exporters around the Asian region (26).…”

“…Although there is a large amount of data about the emergence of antimicrobial-resistant enterococci in Southeast Asian countries, most of this information is fragmented since it has been published in different papers in different countries over several decades (41)(42)(43)(44). However, several studies show the extent of unregulated and inappropriate use of antimicrobials in food animals in developing Southeast Asian countries such as Vietnam and Malaysia (23,25,45). Usui et al (25) obtained results that demonstrate the use of antimicrobials in chickens in Southeast Asian countries, especially Vietnam, to be higher than in developed countries (45).…”

“…Clearly, enterococci with resistance genes may reach humans in several ways, including direct contact with farm personnel (23,62), via wastewater and surface water (55,59,60), or by contact with or consumption of food animals and food of animal origin (23,25). Although the hygienic standards of meat production are high in most developed countries, fecal contamination of meat products cannot be completely eliminated (63).…”