Clonal Structure of Enterococcus faecalis Isolated from Polish Hospitals: Characterization of Epidemic Clones

Abstract

To study the population structure of Enterococcus faecalis from Polish hospitals, 291 isolates were typed by pulsed-field gel electrophoresis and a novel multilocus sequence typing scheme (P. Ruiz-Garbajosa et al., J. Clin. Microbiol. 44:2220-2228, 2006). The isolates originated from geographically widespread medical institutions and were recovered during a 10-year period (1996 to 2005) from different clinical sources. The analysis grouped the isolates into five epidemic and 71 sporadic clones. The importance of the previously identified global clonal complexes CC2 and CC9 was corroborated by our findings that two of the Polish epidemic clones, A and J, were classified into these clonal complexes (CCs). However, the two most predominant clones, C (ST40) and F (CC87), did not cluster in the aforementioned CCs and may represent novel epidemic CCs. These clones may have emerged in Central Europe. Clone F, carrying glycopeptide resistance determinants of VanA or VanB phenotypes, caused several outbreaks in hematology units and appeared to be the most prevalent clone in recent years in Poland. Antimicrobial susceptibility testing and additional tests for pathogenicity-related phenotypes (hemolysin and gelatinase production) and genes (asa1 and esp) were performed to further characterize these epidemic clones. Multidrug resistance, glycopeptide resistance, presence of asa1, and production of hemolysin appeared to be statistically significant features related to epidemicity. Production of gelatinase was significant for two of the epidemic clones, whereas presence of the esp gene was not specific for the epidemic clones.Enterococci are known to be opportunistic nosocomial pathogens capable of causing life-threatening infections, such as endocarditis and bacteremia, mostly in immunocompromised patients (17,18,20). Since Enterococcus spp. are resistant to multiple antibacterial drugs, there are only limited options for effective therapy and prophylaxis of serious infections (16, 21). The two enterococcal species most often isolated from clinical infections are Enterococcus faecalis and Enterococcus faecium, the first of which is responsible for the majority of infections, whereas in the latter, multidrug resistance has predominantly accumulated (18).Molecular epidemiological studies of E. faecium using multilocus sequence typing (MLST) revealed the existence of hostspecific lineages and a distinct genetic subpopulation named clonal complex 17 (CC17) (12,34,35) that is responsible for the majority of hospital-related infections and outbreaks and that has spread globally. Until now, less has been known about the population structure of E. faecalis. Analyzing 110 isolates by MLST, Ruiz-Garbajosa et al. identified 55 sequence types (ST) and four major CCs, two of which, CC2 and CC9, were significantly enriched among nosocomial isolates and were considered to represent hospital-adapted complexes, equivalent to E. faecium CC17. Furthermore, CC2 and CC9 corresponded to the previously identified E. faecalis BVE complex (␤-lactama...

Human and Swine Hosts Share Vancomycin-Resistant Enterococcus faecium CC17 and CC5 and Enterococcus faecalis CC2 Clonal Clusters Harboring Tn 1546 on Indistinguishable Plasmids

“…Examples of isolates showing the same or similar PFGE types but clustering in different STs have previously been described for both E. faecalis (13,27) and E. faecium (7). It is known that large plasmids or integrative conjugative elements (ICEs), which are frequent in E. faecium (16,21,29,55), can affect digested genomic DNA banding patterns (34,49).…”

Occurrence, Population Structure, and Antimicrobial Resistance of Enterococci in Marginal and Apical Periodontitis

“…Besides the genetic diversity, common genetic origins and a similar population structure are shared by E. faecalis isolates in this study and those in the database, e.g., 86.1% E. faecalis isolates and 27 of 40 STs presenting in the MLST database and the major ST21, ST40, and ST30 also predominating in the database. The database documents that most strains in ST21 (80%), CC40 (81.6%), and CC30 (77.8%) are from hospitalized patients mostly from Poland (17,31); the remaining strains are from human community and animal reservoirs in Spain, Denmark, and The Netherlands (17,31). The presence of corresponding STs and CCs in both our study and the database indicates that oral E. faecalis strains can be cross transmitted from other sources, such as hospitalized patients, healthy individuals, and animals in different countries.…”

“…The eBURST snapshots illustrate a high genetic diversity of oral E. faecalis isolates that were assigned to 40 different STs, five CCs and 29 singletons. A number of studies demonstrate a high genetic diversity of E. faecalis isolated from hospitalized patients, surveillance samples, animals, and food (17,18,31). Based on the hypothesis that all the STs within one clonal complex represent ancestry and evolutionary descent (41), the 108 isolates are supposed to be the descendants of 33 ancestries from the whole E. faecalis MLST database.…”

“…Molecular typing of E. faecalis and E. faecium, e.g., multilocus sequence typing (MLST), has shown the emergence of specific genetic lineages of enterococci, i.e., hospitaladapted clones of antimicrobial-resistant E. faecalis and E. faecium (11,40). E. faecalis clonal complexes CC2, CC9, and CC87 seem to be widely distributed in hospital patients in Europe and the United States (17,31).…”

Characterization of Small-Colony Variants of Enterococcus faecalis Isolated from Chickens with Amyloid Arthropathy

“…The PFGE was able to specify different subgroups of isolates while most isolates included in the MLST demonstrated the same ST or, in the few exceptions, a closely related ST. By MLST, the genes encoding enzymes involved in conserved metabolic and information processes are compared at the DNA sequence level (24) and results are portable and easily comparable via Internet-based servers. E. faecalis isolates demonstrating ST82 were first described from a human clinical infection (16) and have recently been shown to be associated with amyloid arthropathy worldwide (26).…”