Molecular Structure and Transferability of Tn 1546 -Like Elements in Enterococcus faecium Isolates from Clinical, Sewage, and Surface Water Samples in Iran

Abstract

The molecular structure and transferability of Tn1546 in 143 vancomycin-resistant Enterococcus faecium (VREF) isolates obtained from patients (n ‫؍‬ 49), surface water (n ‫؍‬ 28), and urban and hospital sewage (n ‫؍‬ 66) in Tehran, Iran, were investigated. Molecular characterization of Tn1546 elements in vanA VREF was performed using a combination of restriction fragment length polymorphism analysis and DNA sequencing of the internal PCR fragments of vanA transposons. Long-PCR amplification showed that the molecular size of Tn1546 elements varied from 10.8 to 12.8 kb. The molecular analysis of Tn1546 showed that 45 isolates (31.5%) harbored a deletion/mutation upstream from nucleotide 170. No horizontal transfer of Tn1546 was observed following filter-mating conjugation with these isolates. Nevertheless, the rates of transferability for other isolates were 10 ؊5 to 10 ؊6 per donor. Insertion sequences IS1216V and IS1542 were present in 103 (72%) and 138 (96.5%) of the isolates, respectively. The molecular analysis of Tn1546 elements resulted in three genomic organizations. The genomic organization lineage 1 was dominated by the isolates from clinical samples (3.4%), lineage 2 was dominated mostly by sewage isolates (24.5%), and lineage 3 contained isolates obtained from all sources (72.1%). The genetic diversity determined using pulsed-field gel electrophoresis (PFGE) revealed a single E. faecium clone, designated 44, which was common to the samples obtained from clinical specimens and hospital and municipal sewage. Furthermore, the results suggest that lineage 3 Tn1546 was highly disseminated among our enterococcal isolates in different PFGE patterns.

Diversity of plasmids and Tn1546-type transposons among VanA Enterococcus faecium in Poland

“…The population structure determined for Polish VR Efm VanA closely resembled these of hospital-associated E. faecium in other countries. High diversity of STs/MTs is consistent with the presence of polyclonal hospital population of E. faecium that subsequently acquires vancomycin resistance determinants [13, 14]. The vast majority of isolates grouped into hospital lineage 17/18, mostly represented by STs 17, 117, 18, 132, 202 and lineage 78, which included STs 78, 192 and 412.…”

“…The vanA gene cluster is carried on Tn 1546 -type transposons [12], which show a significant degree of heterogeneity, associated with presence of point mutations, deletions and presence of various ISs [13, 14]. A few studies demonstrated the location of Tn 1546 on Inc18, pRUM-like, pMG1-like, and pLG1 plasmids [15, 16]; however, the knowledge of vanA -plasmids and their epidemiology is still far from being satisfactory and may differ significantly among countries.…”

Prevalence of virulence factors and antibiotic resistance in vancomycin-resistant Enterococcus faecium isolated from sewage and clinical samples in Iran

“…[3,6] Other virulence factors such as Esp and Hly have been described in both E. faecalis and E. faecium. [4,7] In continuation with our previous reports, [8,9] here we investigate the virulence factors in E. faecium isolated from clinical setting and sewage in Iran, where no such information is available.…”

Streptococcus gallolyticus subsp. gallolyticus from Human and Animal Origins: Genetic Diversity, Antimicrobial Susceptibility, and Characterization of a Vancomycin-Resistant Calf Isolate Carrying a vanA -Tn 1546 -Like Element

“…In enterococci, differences between Tn1546-related elements from animals and humans (25,45), as well as heterogeneity in Tn1546-like elements with IS1216 insertions (46,47), have been described previously. These features has not been reported previously for S. gallolyticus subsp.…”