The Dominant Sequence Types of Vancomycin-Resistant Enterococcus faecium Among Transplantation Ward Patients

Abstract In addition to an overall rise in vancomycin-resistant Enterococcus faecium (VREfm), an increase in certain other strain types has been reported in Germany over the past few years. Outbreak analyses at Charité - Universitätsmedizin Berlin revealed the frequent occurrence of VREfm ST117 CT71 isolates in 2017 and 2018. To investigate whether ST117 CT71 have emerged in recent years or whether these strains have been circulating for a longer time, we retrospectively analyzed non-outbreak strains that occurred between 2008 and 2018 to identify frequent sequence types (STs) and cluster types (CTs). Methods In total, 120 VREfm isolates obtained from clinical and surveillance cultures from the years 2008, 2013, 2015, and 2018 were analyzed. Thirty isolates per year comprising the first 7 to 8 non-outbreak isolates of each quarter of the respective year were sequenced using whole genome sequencing. MLST and cgMLST were determined as well as resistance genes and virulence factors. Risk factors for VREfm ST117 were analyzed in a multivariable analysis with patient characteristics as possible confounders. Results The percentage of VREfm of type ST117 increased from 17% in 2008 to 57% in 2018 (p=0.012). In 2008, vanA genotype accounted for 80% of all ST117 isolates compared to 6% in 2018. VanB CT71 first appeared in 2018 and predominated over all other ST117 at 43% (p<0.0001). The set of resistance genes and virulence factors in CT71 (msrC, efmA, ermB, dfrG, and aac(6')-Ii) and virulence factors (acm, esp, hyl, ecbA and sgrA) was also found in other ST117 non-CT71 strains, mainly in CT36. The study population did not differ among the different calendar years analyzed in terms of age, gender, length of stay, or ward type (each p>0.2). Conclusion This study revealed an increase in ST117 strains from 2008 to 2018, accompanied by a shift toward CT71 strains with the vanB genotype in 2018. We did not detect resistance or virulence traits in CT71 that could confer survival advantage compared to other CTs among ST117 strains. To date, it is not clear why ST117 and in particular strain type ST117 CT71 predominates over other strains.

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

Applied and Environmental Microbiology ◽

10.1128/aem.00650-13 ◽

2013 ◽

Vol 79 (15) ◽

pp. 4528-4533 ◽

Cited By ~ 21

Author(s):

Yitbarek Getachew ◽

Latiffah Hassan ◽

Zunita Zakaria ◽

Saleha Abdul Aziz

Keyword(s):

Enterococcus Faecalis ◽

Enterococcus Faecium ◽

Clonal Complex ◽

Housekeeping Genes ◽

Vancomycin Resistant Enterococcus ◽

Content Type ◽

Vancomycin Resistant Enterococci ◽

Vancomycin Resistant ◽

Sequence Types ◽

Representative Samples

ABSTRACTVancomycin-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 ofEnterococcus faecium(n= 14) andEnterococcus faecalis(n= 11) isolates were sequenced and analyzed using the MLST databases eBURST and goeBURST. We found five sequence types (STs) ofE. faeciumand six STs ofE. faecalisexisting in Malaysia.Enterococcus faeciumisolates belonging to ST203, ST17, ST55, ST79, and ST29 were identified, andE. faeciumST203 was the most common among humans. The MLST profiles ofE. faeciumfrom 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. faecalisisolates 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 ofE. faeciumandE. faecalissupports 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.

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