Intestinal Translocation of Clinical Isolates of Vancomycin-Resistant Enterococcus faecalis and ESBL-Producing Escherichia coli in a Rat Model of Bacterial Colonization and Liver Ischemia/Reperfusion Injury

Abstract

The objectives of this study were to develop a rat model of gastrointestinal colonization with vancomycin-resistant Enterococcus faecalis (VRE) and extended-spectrum beta-lactamase (ESBL)-producing E. coli and to evaluate intestinal translocation to blood and tissues after total and partial hepatic ischemia. Methods - We developed a model of rat colonization with VRE and ESBL-E coli. Then we studied four groups of colonized rats: Group I (with hepatic pedicle occlusion causing complete liver ischemia and intestinal stasis); Group II (with partial liver ischemia without intestinal stasis); Group III (surgical manipulation without hepatic ischemia or intestinal stasis); Group IV (anesthetized without surgical manipulation). After sacrifice, portal and systemic blood, large intestine, small intestine, spleen, liver, lungs, and cervical and mesenteric lymph nodes were cultured. Endotoxin concentrations in portal and systemic blood were determined. Results – The best inocula were: VRE: 2.4×1010 cfu and ESBL-E. coli: 1.12×1010 cfu. The best results occurred 24 hours after inoculation and antibiotic doses of 750 µg/mL of water for vancomycin and 2.1 mg/mL for ceftriaxone. There was a significantly higher proportion of positive cultures for ESBL-E. coli in the lungs in Groups I, II and III when compared with Group IV (67%; 60%; 75% and 13%, respectively; p:0.04). VRE growth was more frequent in mesenteric lymph nodes for Groups I (67%) and III (38%) than for Groups II (13%) and IV (none) (p:0.002). LPS was significantly higher in systemic blood of Group I (9.761±13.804 EU/mL−p:0.01). No differences for endotoxin occurred in portal blood. Conclusion –We developed a model of rats colonized with resistant bacteria useful to study intestinal translocation. Translocation occurred in surgical procedures with and without hepatic ischemia-reperfusion and probably occurred via the bloodstream. Translocation was probably lymphatic in the ischemia-reperfusion groups. Systemic blood endotoxin levels were higher in the group with complete hepatic ischemia.

Use of molecular typing to investigate bacterial translocation from the intestinal tract of chlorpyrifos-exposed rats

“…Although they came from the same species, translocated strains and non-translocated strains differed clearly in terms of the ERIC2-PCR and RAPD-PCR patterns (77.5 % of strains). As reported in the literature [26], we concluded that BT did not occur in samples when the extra-intestinal organs (liver, spleen, Peyer’s patches, MLNs, adipose tissue, and kidneys) were sterile. One could argue that the intestinal bacteria found in the extra-intestinal tissue samples resulted from bacterial contamination and not from BT.…”

“…Although molecular typing has often been used to characterized BT in a clinical setting [24, 25], there are few literature data on the use of these techniques to detect translocation from the intestinal tract in animal models [26]. To the best of our knowledge, the present study is the first to have employed molecular typing (ERIC2-PCR and RAPD-PCR) techniques in the detection of BT in the rat.…”

Determination of clonal relationships and virulence genes of vancomycin-resistant enterococcus spp. isolated from colonized and infected patients

“…As a result, patient feces are contaminated with VRE, leading to the development of exogenous infections 5 . Therefore, in the control and prevention of the spread of VRE infections, it is important to timely detect patients with VRE colonization, elucidate their relationship with hospital infection outbreaks, and identify virulence factors for colonization and infection 6,7 .…”

Exopolysaccharide-mediated surface penetration as new virulence trait in Enterococcus faecalis

“…E. faecalis ranks as the fourth most important cause of hospital-acquired infections and the third leading cause of bacteremia, where its intrinsic or acquired antibiotic resistance contributes to its pathogenicity [2]. Recent evidence suggests that E. faecalis has a remarkable ability to translocate from the GI to reach the bloodstream and colonize distant anatomical locations [3][4][5][6]. For instance, in patients treated with antibiotics during allogeneic hematopoietic stem cell transplantation, colonization of the intestinal tract by antibiotic-resistant enterococci has been observed prior to the emergence of bloodstream infections [4].…”

“…For instance, in patients treated with antibiotics during allogeneic hematopoietic stem cell transplantation, colonization of the intestinal tract by antibiotic-resistant enterococci has been observed prior to the emergence of bloodstream infections [4]. Moreover, the use of broad-spectrum antimicrobials has been suggested to be a predisposing factor that promotes the translocation of vancomycinresistant enterococci [5]. While the mechanisms of enterococcal migration remain largely unexplored, recent evidence indicates that this process is mediated by the formation of bacterial aggregates through cellsurface appendages, adhesins, and other unknown factors [4][5][6][7][8][9][10].…”