Clonal dissemination of vancomycin-resistant Enterococcus faecium ST412 in a Brazilian region

First characterization of Tn1546-like structures of vancomycin-resistant Enterococcus faecium Thai isolates

INTRODUCTION

Vancomycin-resistant Enterococcus faecium (VREfm) carrying vanA was first isolated from patient at Siriraj Hospital, Thailand in 2004. Since then, VREfm isolates have been detected increasingly in this 2500-bed university hospital. To understand the epidemiology of vanA VREfm in this setting, the isolates collected during 2004-2013 were characterized.

METHODS

A total of 49 vanA VREfm isolates previously confirmed by multiplex PCR were characterized by determining resistance phenotypes to vancomycin, teicoplanin, ampicillin and ciprofloxacin by broth microdilution method. Multilocus sequence typing (MLST) and virulence genes of those isolates were investigated. The Tn1546 structure diversity was studied by long-range overlapping PCR and primer walking sequencing.

RESULTS

Of all isolates studied, 9 sequence types (ST17, ST80, ST78, ST730, ST203, ST18, ST280, ST64, ST323) in clonal complex 17 and a novel ST1051 were revealed. The esp-positive isolates were 73.5%. Of all vanA operons characterized, at least 9 types of Tn1546-like structures were detected. All of vanA determinants contained 5'-end different from the Tn1546 prototype. Approximately 47% of them also carried the insertion sequence IS1251 at the intergenic region between vanS and vanH. Interestingly, another IS (ISEfa4) was found to be inside the sequence of IS1251 in ST17 isolate.

CONCLUSION

Heterogeneity of vanA VREfm was observed. Nearly all of isolates studied belonged to CC17. One novel ST1051 strain was detected. Isolates in the initial period carried vanA operon similar to the prototype. The diversity of vanA determinants has been increased in the recent isolates. A novel vanA operon structure was detected.

The impact of essential oils on antibiotic use in animal production regarding antimicrobial resistance - a review

Population growth directly affects the global food supply, demanding a higher production efficiency without farmland expansion - in view of limited land resources and biodiversity loss worldwide. In such scenario, intensive agriculture practices have been widely used. A commonly applied method to maximize yield in animal production is the use of subtherapeutic doses of antibiotics as growth promoters. Because of the strong antibiotic selection pressure generated, the intense use of antibiotic growth promoters (AGP) has been associated to the rise of antimicrobial resistance (AMR). Also, cross-resistance can occur, leading to the emergence of multidrug-resistant pathogens and limiting treatment options in both human and animal health. Thereon, alternatives have been studied to replace AGP in animal production. Among such alternatives, essential oils and essential oil components (EOC) stand out positively from others due to, besides antimicrobial effectiveness, improving zootechnical indexes and modulating genes involved in resistance mechanisms. This review summarizes recent studies in essential oils and EOC for zoonotic bacteria control, providing detailed information about the molecular-level effects of their use in regard to AMR, and identifying important gaps to be filled within the animal production area.

Genomic Epidemiology of Vancomycin-Resistant Enterococcus faecium (VREfm) in Latin America: Revisiting The Global VRE Population Structure

Little is known about the population structure of vancomycin-resistant Enterococcus faecium (VREfm) in Latin America (LATAM). Here, we provide a complete genomic characterization of 55 representative Latin American VREfm recovered from 1998-2015 in 5 countries. The LATAM VREfm population is structured into two main clinical clades without geographical clustering. Using the LATAM genomes, we reconstructed the global population of VREfm by including 285 genomes from 36 countries spanning from 1946 to 2017. In contrast to previous studies, our results show an early branching of animal related isolates and a further split of clinical isolates into two sub-clades within clade A. The overall phylogenomic structure of clade A was highly dependent on recombination (54% of the genome) and the split between clades A and B was estimated to have occurred more than 2,765 years ago. Furthermore, our molecular clock calculations suggest the branching of animal isolates and clinical clades occurred ~502 years ago whereas the split within the clinical clade occurred ~302 years ago (previous studies showed a more recent split between clinical an animal branches around ~74 years ago). By including isolates from Latin America, we present novel insights into the population structure of VREfm and revisit the evolution of these pathogens.

CRISPR elements and their association with antimicrobial resistance and virulence genes among vancomycin-resistant and vancomycin-susceptible enterococci recovered from human and food sources

We aimed to investigate the occurrence of CRISPR elements in the genomes of vancomycin-resistant (VRE) and vancomycin-susceptible (VSE) enterococci and their association with the presence of antimicrobial resistance and virulence genes. We analyzed 180 isolates, including 91 VRE and 89 VSE. Isolates were identified by PCR or MALDI-TOF. Antimicrobial susceptibility and MICs for vancomycin were determined by the disk-diffusion method and E-test®, respectively. The presence of resistance and virulence genes, as well as CRISPR elements, was investigated by PCR. We identified 95 (53%) E. faecalis, 78 (43%) E. faecium, five (2.8%) E. gallinarum, and one (0.6% each) E. casseliflavus and E. durans. The highest and the lowest non-susceptibility frequencies were observed for erythromycin (n = 152; 84.4%) and fosfomycin (n = 5; 2.8%), respectively. Most erythromycin-resistant isolates had the erm(B) gene (106/152; 69.7%). Of 118 (65.6%) isolates with high-level resistance to aminoglycoside, 69 (58.5%) had at least one aminoglycoside resistance gene, mostly ant(6)-Ia and aac(6')-Ie + aph(2″)-Ia. We found at least one virulence gene among 135 (75%) isolates, mostly gelE (79/180; 43.9%). Ninety-two (51.1%) isolates had at least one CRISPR element, especially CRISPR3 (62/92; 67.4%). CRISPR elements were more common among E. faecalis, in which we observed a relationship between the absence of CRISPR and the presence of the vanA resistance gene, and the hyl and esp virulence genes. Among VRE. faecium, a relationship was found between the absence of CRISPR and the hyl gene. In conclusion, we found evident associations between the lack of CRISPR elements with species, multidrug resistance, and major resistance- and virulence-associated genes.

Draft Genome Sequence of Vancomycin-Resistant Enterococcus faecium UEL170 (Sequence Type 412), Isolated from a Patient with Urinary Tract Infection in a Tertiary Hospital in Southern Brazil

Enterococcus faecium is a leading cause of health care-associated infections, with specific lineages circulating in hospital settings worldwide. Here, we report the draft genome sequence of the multidrug-resistant and biofilm-producing E. faecium UEL170, sequence type 412 (ST412), isolated from an inpatient with a urinary tract infection. This strain is a member of clonal complex 17 (CC17), a globally hospital-associated clone.

Characterization of Clinical Vancomycin-Resistant Enterococcus faecium Isolated in Eastern Hungary

OBJECTIVES

The aim of our study was to characterize and elicit the genetic relatedness of emerging vancomycin-resistant enterococci (VRE) isolated between 2012 and 2015 at a teaching hospital in Debrecen, Hungary.

RESULTS

Altogether 43 nonduplicate vancomycin-resistant Enterococcus faecium (VREfm) clinical isolates were obtained. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used for species identification. Isolates showed 100% resistance to ampicillin and ciprofloxacin while 81.4% were resistant to gentamicin. PCR analysis revealed the presence of VanB in 40 and VanA in 3 isolates. Among ace, agg, and esp virulence genes only esp was found in seven cases. Modified microtiter-plate test showed 13 weak and 4 moderate biofilm producer isolates. Pulsed-field gel electrophoresis revealed nine pulsotypes. According to multilocus sequence typing all of the tested isolates belonged to clonal complex 17 (CC17).

CONCLUSIONS

We report on the alarming emergence of multidrug-resistant VREfm belonging to CC17 at a tertiary hospital in Eastern Hungary. This is the first report of sequence types 412 and 364 from this region. Although outbreak did not occur the increasing prevalence of VREfm is of concern and dissemination must be prevented with proper infection control measures and regular VRE screening.

Evolution of virulence in Enterococcus faecium, a hospital-adapted opportunistic pathogen

Enterococci are long-standing members of the human microbiome and they are also widely distributed in nature. However, with the surge of antibiotic-resistance in recent decades, two enterococcal species (Enterococcus faecalis and Enterococcus faecium) have emerged to become significant nosocomial pathogens, acquiring extensive antibiotic resistance. In this review, we summarize what is known about the evolution of virulence in E. faecium, highlighting a specific clone of E. faecium called ST796 that has emerged recently and spread globally.