Multiresistant Enterococcus Faecium Research Articles

Antibacterial activity evaluation of cambuí extract against multi-resistant Enterococcus faecium

Bacterial resistance is a global public health issue. Among these pathogens, Enterococcus faecium nosocomial has been highlighted due to its potential to cause bacteremia infections. The incidence of resistant Enterococcus faecium bacteremia has enhanced over time, thereby, it has caused high rates of mortality. Hence, it led to the interest in natural drugs. Plant extracts from the Myrtaceae family have a broad-spectrum antimicrobial action. Among the plants of this family, we can highlight cambuí, due to its wide variety of bioactive compounds such as phenolic compounds. Polyphenols are bioactive molecules that can inhibit the growth of resistant bacteria such as Enterococcus faecium. For this, the present study aimed to obtain bioactive extracts from cambuí using pressurized hot water to grow inhibition of multi-resistant Enterococcus faecium nosocomial. In the present study, antibacterial compounds were obtained after extraction kinetics over 120 minutes at a temperature of 50º C, a flow rate of 1 mL/min-1, and a constant pressure of 200 bar using water as the extraction solvent. Flavonoids and other phenolic compounds from cambuí extracts were quantified by spectrophotometric methods. The TSA using the well-diffusion method was used to verify the sensitivity of the bacterium Enterococcus faecium against cambuí aqueous extract. The results showed that the best extraction time was 60 minutes using 60 mL of water. The cambuí aqueous extract showed a relevant amount of flavonoids and other phenolic compounds, hence, this extract was able to inhibit the growth of the bacterium Enterococcus faecium resistant to Ampicillin, Imipenem, Vancomycin, and Teicoplanin.

Identification of a Novel Two-Peptide Lantibiotic from Vagococcus fluvialis.

ABSTRACTInfections caused by multiresistant pathogens have become a major problem in both human and veterinary medicine. Due to the declining efficacy of many antibiotics, new antimicrobials are needed. Promising alternatives or additions to antibiotics are bacteriocins, antimicrobial peptides of bacterial origin with activity against many pathogens, including antibiotic-resistant strains. From a sample of fermented maize, we isolated a Vagococcus fluvialis strain producing a bacteriocin with antimicrobial activity against multiresistant Enterococcus faecium. Whole-genome sequencing revealed the genes for a novel two-peptide lantibiotic. The production of the lantibiotic by the isolate was confirmed by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry, which revealed distinct peaks at 4,009.4 m/z and 3,181.7 m/z in separate fractions from reversed-phase chromatography. The combination of the two peptides resulted in a 1,200-fold increase in potency, confirming the two-peptide nature of the bacteriocin, named vagococcin T. The bacteriocin was demonstrated to kill sensitive cells by the formation of pores in the cell membrane, and its inhibition spectrum covers most Gram-positive bacteria, including multiresistant pathogens. To our knowledge, this is the first bacteriocin characterized from Vagococcus.IMPORTANCE Enterococci are common commensals in the intestines of humans and animals, but in recent years, they have been identified as one of the major causes of hospital-acquired infections due to their ability to quickly acquire virulence and antibiotic resistance determinants. Many hospital isolates are multiresistant, thereby making current therapeutic options critically limited. Novel antimicrobials or alternative therapeutic approaches are needed to overcome this global problem. Bacteriocins, natural ribosomally synthesized peptides produced by bacteria to eliminate other bacterial species living in a competitive environment, provide such an alternative. In this work, we purified and characterized a novel two-peptide lantibiotic produced by Vagococcus fluvialis LMGT 4216 isolated from fermented maize. The novel lantibiotic showed a broad spectrum of inhibition of Gram-positive strains, including vancomycin-resistant Enterococcus faecium, demonstrating its therapeutic potential.

Effect of vancomycin on the proteome of the multiresistant Enterococcus faecium SU18 strain.

This study highlights the power of proteomics in the study of differential protein expression in a multiresistant Enterococcus faecium strain when subjected to vancomycin stress.

Deep coma and diffuse white matter abnormalities caused by sepsis-associated encephalopathy

In January, 2012, a 53-year-old woman with a history of progressive polyposis coli and hypertension was admitted to the intensive care unit (ICU) of our hospital because of septic shock 4 days after laparoscopic subtotal colectomy. She was intubated and mechanically ventilated, underwent emergent re-laparotomy for anastomotic leakage, and was treated with antibiotics. Blood cultures were positive for multiresistant Enterococcus faecium. After re-laparotomy the patient was sedated with midazolam for 2 days. The neurologist was consulted on the fourth postoperative day because of the patient’s persistent low level of consciousness. On neurological examination, we found no eye opening or motor response to a painful stimulus, intact brainstem refl exes, and generalised arefl exia of arms and legs with indiff erent plantar refl exes. We observed no signs indicative of minimally convulsive status epilepticus. During the period of septic shock and surgery, blood pressure had not been lower than 100/50 mm Hg and laboratory tests did not show abnormalities that could explain the patient’s coma. Non-contrast CT (NCCT) of the brain showed abnormal hypodensity of the complete white matter with swelling of the entire brain (fi gure); CT angiography was normal. Electromyography showed absence of motor unit potentials in arm and leg muscles without evidence for accompanying neuropathy. We made a diagnosis of sepsis-associated encephalopathy and critical illness myopathy. Because of the deep coma and the diff use and severely abnormal aspect of the white matter—both associated with poor outcome—dis continuation of treatment was discussed, but we recommended to continue treatment. On the ninth postoperative day the patient opened her eyes in response to painful stimuli, but there was still no motor response. Follow-up NCCT showed no improvement of the white matter abnormalities. In the following weeks the condition of the patient gradually improved and 4 weeks after the re-laparotomy she had regained full consciousness. When the patient was discharged from the ICU her muscle strength had gradually improved with movements against gravity now possible. At that time brain MRI was normal except for a small number of white matter lesions (fi gure). The patient was transferred to a rehabilitation centre 6 weeks after the initial onset of septic shock. At that point she was able to walk short distances. At last follow-up on Aug 19, 2012, she had regained independence in activities of daily living and was living at home. Sepsis-associated encephalopathy is a severe complication of sepsis and is associated with poor outcome. The reported incidence ranges from 9% to 71% because of variations in the defi nition. A recent study in an ICU showed that patients with sepsis secondary to intestinal infections are prone to develop septic encephalopathy, with Escherichia coli and Enterococcus faecium among the most frequently cultured bacteria. The exact pathogenesis of sepsis-associated encephalopathy remains unclear; disruption of the blood-brain barrier and mitochondrial dysfunction are probably involved. Imaging of the brain can show atrophy and periventricular white matter lesions. The diff use and severe white matter abnormalities like those we observed in our patient are rare and have been associated with poor outcome. This case shows that severe encephalopathy with extensive white matter lesions can be a reversible condition. Clinicians should realise that the fi rst signs of improvement of the clinical condition could still be observed beyond 7 days after onset.

Intestinal Colonization with Enterococcus faecium Does Not Influence Pulmonary Defense against Pseudomonas aeruginosa in Mice

BackgroundEnterococci, and especially multiresistant Enterococcus faecium, are increasingly found colonizing hospitalized patients. This increased prevalence of colonization is not only associated with an increased prevalence of infections caused by enterococci, but also by infections with other nosocomial pathogens. In this study we investigated the causality of this observed relationship, by determining the influence of intestinal colonization with E. faecium on pulmonary defense against Pseudomonas aeruginosa.Methodology/Principal FindingsThree groups of mice were tested; 2 groups of mice were pre-treated with vancomycin, of which one group was subsequently treated by oral gavage of vancomycin-resistant E. faecium (VRE). The third group did not receive any pre-treatment. P. aeruginosa pneumonia was induced in all mice. Vancomycin treatment resulted in intestinal gram-negative bacterial overgrowth and VRE treatment resulted in colonization throughout the intestines. All 3 groups of mice were able to clear P. aeruginosa from the lungs and circulation, with comparable lung cytokine responses and lung damage. Mice treated with vancomycin without VRE colonization displayed modestly increased plasma levels of TNF-α and IL-10.ConclusionOvergrowth of E. faecium and/or gram-negative bacteria does not impact importantly on pulmonary defense against P. aeruginosa pneumonia.

Antibiotic-Induced Enterococcal Expansion in the Mouse Intestine Occurs throughout the Small Bowel and Correlates Poorly with Suppression of Competing Flora

To test the hypothesis that establishing gastrointestinal colonization with multiresistant Enterococcus faecium (VRE) C68 results from expansion of the enterococcal population in the upper small bowel, we compared VRE quantities recovered from the proximal, middle, and distal segments of the small bowel from mice treated with different antimicrobial agents. Antibiotics associated with high-level VRE fecal colonization (cefotetan, ceftriaxone, clindamycin, and ticarcillin-clavulanic acid) increased VRE quantities in all small-bowel segments, whereas cefepime and piperacillin-tazobactam did not. Enterococcal expansion did not correlate with reductions in numbers of native gram-negative or anaerobic flora. Green fluorescence protein-expressing E. faecium bacteria were found adjacent to the small bowel epithelial lining in colonized mice. These data indicate that enterococcal bowel colonization begins within the proximal small bowel and does not correlate with inhibition of other cultivable flora. Host or enterococcal factors induced by exposures to certain antibiotics may play a role in facilitating E. faecium colonization of the mammalian gastrointestinal tract.

Conjugal transfer of aminoglycoside and macrolide resistance betweenEnterococcus faeciumisolates in the intestine of streptomycin-treated mice

The purpose was to study conjugal transfer of resistance genes between a multi-resistant Enterococcus faecium isolate and a sensitive E. faecium isolate. Co-transfer of erm(B)-Tn5405-like element and aac(6')-Ie-aph(2'')-Ia was obtained in both in vivo and in vitro. Plasmid profiles and Southern blots showed that both the erm(B)-Tn5405-like element and aac(6')-Ie-aph(2'')-Ia were placed on the same large plasmid (>147 kb). These data show to our knowledge the first co-transfer of the erm(B)-Tn5405-like element and aac(6')-Ie-aph(2'')-Ia. The in vivo study also indicates that transfer of resistance genes between enterococci might occur under natural conditions in the gut of animals.

Conjugal transfer of aminoglycoside and macrolide resistance between Enterococcus faecium isolates in the intestine of streptomycin-treated mice

The purpose was to study conjugal transfer of resistance genes between a multi-resistant Enterococcus faecium isolate and a sensitive E. faecium isolate. Co-transfer of erm(B)-Tn 5405-like element and aac(6 ′)- Ie-aph(2 ″)- Ia was obtained in both in vivo and in vitro. Plasmid profiles and Southern blots showed that both the erm(B)-Tn 5405-like element and aac(6 ′)- Ie-aph(2 ″)- Ia were placed on the same large plasmid (>147 kb). These data show to our knowledge the first co-transfer of the erm(B)-Tn 5405-like element and aac(6 ′)- Ie-aph(2 ″) -Ia. The in vivo study also indicates that transfer of resistance genes between enterococci might occur under natural conditions in the gut of animals.

Conjugal transfer of aminoglycoside and macrolide resistance between Enterococcus faecium isolates in the intestine of streptomycin-treated mice

The purpose was to study conjugal transfer of resistance genes between a multi-resistant Enterococcus faecium isolate and a sensitive E. faecium isolate. Co-transfer of erm(B)-Tn5405-like element and aac(6′)-Ie-aph(2′)-Ia was obtained in both in vivo and in vitro. Plasmid profiles and Southern blots showed that both the erm(B)-Tn5405-like element and aac(6′)-Ie-aph(2′)-Ia were placed on the same large plasmid (>147 kb). These data show to our knowledge the first co-transfer of the erm(B)-Tn5405-like element and aac(6′)-Ie-aph(2′)-Ia. The in vivo study also indicates that transfer of resistance genes between enterococci might occur under natural conditions in the gut of animals.

Neue Therapieoption für Intensivpatienten mit Infektionen durch Gram-positive Bakterien - Überblick über Linezolid

During the last decade, there has been an emergence of multiresistant Gram-positive bacteria in intensive care units. Oxazolidinones are a new class of antibiotics without cross-resistance to other antimicrobial agents, and linezolid was recently introduced as first oxazolidinone on the German market. In this overview, we summarize important data and discuss possible indications for linezolid in the treatment of infections in critically ill patients. ANTIMICROBIAL ACTIVITY AND PHARMACOLOGY: The antimicrobial spectrum comprises mainly Gram-positive bacteria, especially Staphylococcus aureus (including MRSA), coagulase-negative staphylococci, enterococci, and streptococci. Linezolid is mostly bacteriostatic and inhibits the bacterial protein synthesis at an early stage. Adults may receive 600 mg b.i.d. intravenously or p. o. About 30 % of the dose are excreted by the kidneys as mother compound and 50 % as metabolites. Dosage reductions are not necessary, even in severe renal impairment, but about one third of the dose is eliminated during dialysis. Overall, linezolid is well tolerated, but approximately 5 % of the patients may suffer from diarrhea or nausea and there have been a few reports about reversible myelosuppressive side effects. Linezolid has been compared to vancomycin for treatment of Gram-positive nosocomial pneumonia, and the clinical cure rates were 66.4 % and 68.1 %, respectively. Linezolid is highly active and bactericidal against pneumococci. The clinical cure rates for treatment of skin and soft tissue infections were 88.1 % with linezolid and 86.1 % with penicillinase-stable penicillins. MRSA were excluded in this study, but it may be assumed from data in vitro that linezolid is equally effective against these bacteria. Data for the treatment of catheter-associated and other forms of bacteremias are mainly derived from the compassionate-use-program, where linezolid has been used in complicated cases, mainly after failure of standard therapy. The majority of infections was caused by multiresistant Enterococcus faecium and the clinical cure rates were approximately 80 %. The currently available data suggest that linezolid will serve as useful agent in the treatment of severe infections caused by multiresistant staphylococci and enterococci. Further studies are necessary to define the role of linezolid as first-line agent, e. g. in the treatment of central venous catheter infections. In light of the severe prognosis of pneumonias caused by MRSA, studies on the combination of linezolid and vancomycin are warranted. Despite the low level of resistance, it seems prudent not to use linezolid as first line agent in the treatment of uncomplicated infections, as long as effective standard antibiotics are available.

Molecular analysis of streptogramin resistance in enterococci

AbstractThe new semi-synthetic streptogramin antibiotic combination quinupristin/dalfopristin (Synercid®) is a promising alternative for a treatment of infections with multiple resistant gram-positive pathogens, e.g. glycopeptide- and multi-resistant Enterococcus faecium. Streptogramins consist of two unrelated compounds, a streptogramin A and B, which act synergistically when given in combination. Mechanisms conferring resistance against both components are essential for resistance against the combination in E. faecium. In this species resistance to streptogramin A compounds is mediated via related acetyltransferases VatD and VatE. Resistance against streptogramins B is either encoded by the widespread ermB gene cluster conferring resistance to macrolide-lincosamide-streptogramin B antibiotics or via expression of the vgbA gene, which encodes a staphylococcal-type lactonase. E. faecalis is intrinsically resistant to streptogramins.Due to a wide use of streptogramins (virginiamycins S/M) in commercial animal farming a reservoir of streptogramin-resistant E. faecium isolates had already been selected. Determinants for streptogramin resistance are localized on plasmids that can be transferred into an E. faecium recipient both in vitro in filter-matings and in vivo in the digestive tracts of rats. Hybridization and sequencing experiments revealed a linkage of resistance determinants for streptogramins A and B on definite plasmid fragments.

Antibacterial activity of quinupristin/dalfopristin. Rationale for clinical use.

Most Gram-positive organisms are highly susceptible to the streptogramin, quinupristin/dalfopristin (RP 59500; Synercid). Minimum inhibitory concentrations for 90% of isolates (MIC90) were < or = 1 mg/L for Staphylococcus aureus, S. epidermidis, S. haemolyticus, Streptococcus pneumoniae, S. pyogenes and Listeria monocytogenes. Importantly, quinupristin/dalfopristin shows similar activity against methicillin-susceptible and -resistant strains of S. aureus, and streptococci with benzylpenicillin (penicillin G)- or erythromycin-acquired resistance. Enterococci have varying susceptibility to quinupristin /dalfopristin, although most isolates tested are susceptible to the drug, including vancomycin-resistant and multiresistant Enterococcus faecium. E. faecalis are generally the least susceptible. Among the Gram-negative respiratory pathogens Moraxella catarrhalis is susceptible and Haemophilus influenzae is moderately susceptible to quinupristin/ dalfopristin; however, Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter spp. are resistant. The drug is active against anaerobic organisms tested, including Clostridium perfringens, Lactobacillus spp., Bacteroides fragilis and Peptostreptococcus. Synergy has been demonstrated in vancomycin-resistant and multiresistant E. faecium, and methicillin-sensitive and -resistant S. aureus with the combination of vancomycin and quinupristin/ dalfopristin. Quinupristin/dalfopristin shows antibacterial activity in vivo in animal models of infection, including methicillin-sensitive and -resistant S. aureus infection in rabbits, S. aureus and S. pneumoniae in mice, and erythromycin-sensitive and -resistant viridans group streptococci infections in rats. The drug is rapidly bactericidal against Gram-positive organisms (with the exception of enterococci) at concentrations similar to or within 4-fold of the MIC, and it has a long postantibiotic effect both in vitro and in vivo.

Controlling nosocomial transmission of multiresistant Enterococcus faecium in a cancer treatment facility : D. Cann, RN, CIC,∗ B. Mustachi, ART, B. Willey, ART, K. O'Quinn, RT, C. Moore, ART, J. Jamison, ART, D. E. Low, MD, A. McGeer, MD. Princess Margaret and Mount Sinai Hospitals, Toronto, Ontario, Canada

Controlling nosocomial transmission of multiresistant Enterococcus faecium in a cancer treatment facility : D. Cann, RN, CIC,∗ B. Mustachi, ART, B. Willey, ART, K. O'Quinn, RT, C. Moore, ART, J. Jamison, ART, D. E. Low, MD, A. McGeer, MD. Princess Margaret and Mount Sinai Hospitals, Toronto, Ontario, Canada

Evaluation and characterization of multiresistant Enterococcus faecium from 12 U.S. medical centers.

Forty-two Enterococcus faecium isolates resistant to ampicillin, penicillin, gentamicin, streptomycin, vancomycin, and teicoplanin (VanA phenotype) from 12 U.S. medical centers were analyzed by pulsed-field gel electrophoresis of chromosomal DNA. The isolates were tested for susceptibility to 12 alternative drugs. The results indicated both intrahospital and interhospital diversity among multiresistant vanA enterococcal isolates. Furthermore, the finding of isolates with identical pulsed-field gel electrophoresis patterns in different centers strongly suggests some interhospital clonal transmission.