oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Hospital-Adapted Clonal Complex 17 Enterococcus Faecium Found among Sand Enterococcal Isolates  [PDF]
Daniela Pinto, Marta Ruivo, Peter Vandamme, Maria de F. S. Lopes
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.31010
Abstract: Though poorly studied, sand is an environment with an extended degree of interaction with man. Enterococcal strains can be found in sand but we do not know to what extent these ubiquitous opportunistic nosocomial pathogens isolated from sand carry antimicrobial resistances and virulence traits. In an attempt to fill in this knowledge gap, two distinct types of sand (beach and children playground) were examined concerning composition in enterococcal species, genetic diversity of isolates and abundance of resistance to antimicrobials and virulence traits. Five different species were found, namely Enterococcus faecium, Enterococcus faecalis, Enterococcus hirae, Enterococcus flavescens and Enterococcus casseliflavus. Although genetic diversity was evident, two different E. faecium clones, common to the two types of sand, were detected, suggesting the existence of clones well adapted to this specific environment or from a common source. E. faecium was associated with multiple antibiotic resistances, including to fluoroquinolones and tetracycline that are commonly used by veterinarians and clinicians. Among the multiresistant E. faecium strains from beach sand, two were from sequence type (ST) 442, which belongs to the wide-spread Hospital-adapted clade CC17. They both carried the esp gene and the genomic island associated with CC17. The other virulence factors screened were disseminated among E. faecalis strains, but seldom detected in the other species, evidencing the existence, in these environments, of E. faecalis strains carrying the same virulence factors as the clinical ones. The present work thus stresses the need to follow-up the presence and characterization of enterococcal strains from both beach and children playground sands and of including these environments in the epidemiological global analysis of enterococcal isolates.
The current MLVA typing scheme for Enterococcus faecium is less discriminatory than MLST and PFGE for epidemic-virulent, hospital-adapted clonal types
Guido Werner, Ingo Klare, Wolfgang Witte
BMC Microbiology , 2007, DOI: 10.1186/1471-2180-7-28
Abstract: All 51 but one hospital isolates from 1996–2006 were assigned to the clonal complex (CC) of epidemic-virulent, hospital-adapted lineages (MLST CC-17; MLVA CC-1) and differed from isolates of sporadic infections and colonizations (n = 7; 1991–1995) and other non-hospital origins (n = 27). Typing of all 58 hospital VRE revealed MLVA as the least discriminatory method (Simpson's diversity index 0.847) when compared to MLST (0.911) and PFGE (0.976). The two most common MLVA types MT-1 (n = 16) and MT-159 (n = 14) combined isolates of several MLST types including also major epidemic, hospital-adapted, clonal types (MT-1: ST-17, ST-18, ST-280, ST-282; MT-159: ST-78, ST-192, ST-203). These data clearly indicate that non-related E. faecium could possess an identical MLVA type being especially critical when MLVA is used to elucidate supposed outbreaks with E. faecium within a single or among different hospitals. Stability of a given MLVA profile MT-12 (ST-117) during an outbreak over a period of five years was also shown.MLVA is a suitable method to assign isolates of E. faecium into distinct clonal complexes. To investigate outbreaks the current MLVA typing scheme for E. faecium does not discriminate enough and cannot be recommended as a standard superior to PFGE.Effective typing of microorganisms is a prerequisite for establishing epidemiological or phylogenetic links between corresponding isolates. A plethora of different methods has been successfully applied to type and differentiate bacterial strains and clonal groups from each other [1]. A critical point to all of these methods is their applicability to answer distinct questions ranging from investigation of outbreaks to establishing rather broad phylogenetic trees of relatedness and arrangement of strains within major clonal complexes. Each method has its respective weaknesses and strengths according to the question(s) addressed and the methodology behind [2-7].Recently, a new method was introduced using small repetit
Enterococcal surface protein Esp is not essential for cell adhesion and intestinal colonization of Enterococcus faecium in mice
Esther Heikens, Masja Leendertse, Lucas M Wijnands, Miranda van Luit-Asbroek, Marc JM Bonten, Tom van der Poll, Rob JL Willems
BMC Microbiology , 2009, DOI: 10.1186/1471-2180-9-19
Abstract: No differences in adherence to Caco-2 cells were found between an Esp expressing strain of E. faecium (E1162) and its isogenic Esp-deficient mutant (E1162Δesp). Mice, kept under ceftriaxone treatment, were inoculated orally with either E1162, E1162Δesp or both strains simultaneously. Both E1162 and E1162Δesp were able to colonize the murine intestines with high and comparable numbers. No differences were found in the contents of cecum and colon. Both E1162 and E1162Δesp were able to translocate to the mesenteric lymph nodes.These results suggest that Esp is not essential for Caco-2 cell adherence and intestinal colonization or translocation of E. faecium in mice.Enterococci are normal inhabitants of the human gastrointestinal (GI) tract, but have emerged as important nosocomial pathogens with high-level resistance to antibiotics, such as ampicillin, aminoglycosides, and vancomycin [1]. They can cause a wide spectrum of diseases, including bacteremia, peritonitis, surgical wound infections, urinary tract infections, endocarditis, and a variety of device-related infections [1-11]. The majority of the enterococcal infections are caused by Enterococcus faecalis. However, in parallel with the increase in nosocomial enterococcal infections, a partial replacement of E. faecalis by Enterococcus faecium has occurred in European and United States hospitals [12-14]http://www.earss.rivm.nl webcite.Molecular epidemiological studies indicated that E. faecium isolates responsible for the majority of nosocomial infections and hospital outbreaks are genetically distinct from indigenous intestinal isolates [15,16]. Recent studies revealed intestinal colonization rates with these hospital-acquired E. faecium as high as 40% in hospital wards, while colonization in healthy people appeared to be almost absent [13,15,16]. It is assumed that adherence to mucosal surfaces is a key process for bacteria to survive and colonize the GI tract. Intestinal colonization of nosocomial E. faecium str
The Enterococcus faecium Enterococcal Biofilm Regulator, EbrB, Regulates the esp Operon and Is Implicated in Biofilm Formation and Intestinal Colonization  [PDF]
Janetta Top, Fernanda L. Paganelli, Xinglin Zhang, Willem van Schaik, Helen L. Leavis, Miranda van Luit-Asbroek, Tom van der Poll, Masja Leendertse, Marc J. M. Bonten, Rob J. L. Willems
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065224
Abstract: Nowadays, Enterococcus faecium is one of the leading nosocomial pathogens worldwide. Strains causing clinical infections or hospital outbreaks are enriched in the enterococcal surface protein (Esp) encoding ICEEfm1 mobile genetic element. Previous studies showed that Esp is involved in biofilm formation, endocarditis and urinary tract infections. In this study, we characterized the role of the putative AraC type of regulator (locus tag EfmE1162_2351), which we renamed ebrB and which is, based on the currently available whole genome sequences, always located upstream of the esp gene, and studied its role in Esp surface exposure during growth. A markerless deletion mutant of ebrB resulted in reduced esp expression and complete abolishment of Esp surface exposure, while Esp cell-surface exposure was restored when this mutant was complemented with an intact copy of ebrB. This demonstrates a role for EbrB in esp expression. However, during growth, ebrB expression levels did not change over time, while an increase in esp expression at both RNA and protein level was observed during mid-log and late-log phase. These results indicate the existence of a secondary regulation system for esp, which might be an unknown quorum sensing system as the enhanced esp expression seems to be cell density dependent. Furthermore, we determined that esp is part of an operon of at least 3 genes putatively involved in biofilm formation. A semi-static biofilm model revealed reduced biofilm formation for the EbrB deficient mutant, while dynamics of biofilm formation using a flow cell system revealed delayed biofilm formation in the ebrB mutant. In a mouse intestinal colonization model the ebrB mutant was less able to colonize the gut compared to wild-type strain, especially in the small intestine. These data indicate that EbrB positively regulates the esp operon and is implicated in biofilm formation and intestinal colonization.
The hylEfm gene in pHylEfm of Enterococcus faecium is not required in pathogenesis of murine peritonitis
Diana Panesso, Maria C Montealegre, Sandra Rincón, Maria F Mojica, Louis B Rice, Kavindra V Singh, Barbara E Murray, Cesar A Arias
BMC Microbiology , 2011, DOI: 10.1186/1471-2180-11-20
Abstract: Five mutants of the hylEfm-region of pHylEfmTX16 from the sequenced endocarditis strain (TX16 [DO]) were obtained using an adaptation of the PheS* system and were evaluated in a commensal strain TX1330RF to which pHylEfmTX16 was transferred by mating; these include i) deletion of hylEfm only; ii) deletion of the gene downstream of hylEfm (down) of unknown function; iii) deletion of hylEfm plus down; iv) deletion of hylEfm-down and two adjacent genes; and v) a 7,534 bp deletion including these four genes plus partial deletion of two others, with replacement by cat. The 7,534 bp deletion did not affect virulence of TX16 in peritonitis but, when pHylEfmTX16Δ7,534 was transferred to the TX1330RF background, the transconjugant was affected in in vitro growth versus TX1330RF(pHylEfmTX16) and was attenuated in virulence; however, neither hylEfm nor hylEfm-down restored wild type function. We did not observe any in vivo effect on virulence of the other deletions of the hylEfm-regionThe four genes of the hylEfm region (including hylEfm) do not mediate the increased virulence conferred by pHylEfmTX16 in murine peritonitis. The use of the markerless counterselection system PheS* should facilitate the genetic manipulation of E. faecium in the future.Enterococcus faecium is a common enterococcal species increasingly isolated from hospital-associated infections in the USA [1]. Compelling evidence suggests that this substantial increase in E. faecium nosocomial infections is due to the worldwide occurrence of a genetic subcluster (designated clonal cluster 17, CC17) which encompasses clones that appear to have evolved independently [2-4]. Several genes have been associated with CC17 E. faecium including i) espEfm, encoding a surface protein which has been associated with increased biofilm formation and urinary tract infection (UTI) [4-6]; ii) some fms genes (two of which are also designated pilA and pilB), encoding putative microbial surface components recognizing adhesive matrix
Comparison of resistance in isolates of Enterococcus faecalis and Enterococcus faecium
F?rat Zafer Mengelo?lu1, Derya ?ak?r2, Hüseyin Agah Terzi2
Journal of Microbiology and Infectious Diseases , 2011,
Abstract: Objectives: Enterococci are Gram positive cocci causing hospital- and community-acquired infections even though they are found in normal flora and they have low-virulence. Their most common species detected as the causative agent are Enterococcus faecalis and Enterococcus faecium. This study aimed to evaluate the differences between the antibiotic susceptibilities of the isolates of these two species isolated from various clinical specimens.Materials and methods: In this study, 68 enterococci strains (40 E.faecalis and 28 E.faecium) isolated from the specimenssent to the clinical microbiology laboratory of Zonguldak Karaelmas Practice and Research Hospital in 2007-2008 were evaluated. Identification at species level and the susceptibilities were performed by using MicroScan WalkAway system (Dade Behring, USA).Results: No resistance to glycopeptides were detected among these isolates. High rates of resistance to ciprofloxacin, rifampicin and erytromycin were observed. Resistance rates to penicillin, ampicillin, ciprofloxacin, rifampicin, erytromycinand high-level gentamicin and streptomycin in E.faecium isolates were found statistically higher than the rates of E.faecalis group (p<0.05).Conclusions: As concordant with the literature, this study observed that E.faecium isolates were significantly more resistant. In enterococcal infections, performing the identification at the species level and determining the antibiotic susceptibility will be helpful in managing of the treatment. J Microbiol Infect Dis 2011;1(1):10-13.
Enterococcal meningitis caused by Enterococcus casseliflavus. First case report
Chiara Iaria, Giovanna Stassi, Gaetano Costa, Rita Di Leo, Antonio Toscano, Antonio Cascio
BMC Infectious Diseases , 2005, DOI: 10.1186/1471-2334-5-3
Abstract: A 77-year-old Italian female presented for evaluation of fever, stupor, diarrhea and vomiting of 3 days duration. There was no history of head injury nor of previous surgical procedures. She had been suffering from rheumatoid arthritis for 30 years, for which she was being treated with steroids and methotrexate. On admission, she was febrile, alert but not oriented to time and place. Her neck was stiff, and she had a positive Kernig's sign. The patient's cerebrospinal fluid was opalescent with a glucose concentration of 14 mg/dl, a protein level of 472 mg/dl, and a white cell count of 200/μL with 95% polymorphonuclear leukocytes and 5% lymphocytes. Gram staining of CSF revealed no organisms, culture yielded E. casseliflavus. The patient was successfully treated with meropenem and ampicillin-sulbactam.E. casseliflavus can be inserted among the etiologic agents of meningitis. Awareness of infection of central nervous system with Enterococcus species that possess an intrinsic vancomycin resistance should be increased.Enterococcal meningitis is an uncommon disease accounting for only 0.3% to 4% of cases of bacterial meningitis which is nevertheless associated with a high mortality rate. It has been described most frequently in patients with neurosurgical conditions (i.e. head trauma, shunt devices, or cerebrospinal fluid leakage), although it can also occur as a "spontaneous" infection complicating remote enterococcal infections such as endocarditis or pyelonephritis [1].Enterococcus faecalis and Enterococcus faecium are the two species most frequently isolated during the course of meningitis (76%–90% and 9–22% respectively). Enterococcus casseliflavus, first considered as a subspecies of E. faecium, is a motile enterococcus that produces a yellow pigment in agar and often has a VanC phenotype determining an intrinsic low level resistance to vancomycin. It has been implicated in a wide variety of infections in humans, especially immunocompromised hosts, but to the best
Status of high level aminoglycoside resistant Enterococcus faecium and Enterococcus faecalis in a rural hospital of central India  [cached]
Mendiratta D,Kaur H,Deotale V,Thamke D
Indian Journal of Medical Microbiology , 2008,
Abstract: Considering the emergence of high level aminoglycoside resistance (HLAR) in enterococci this study was undertaken to determine their status in a rural setting. HLAR by disc diffusion and agar dilution, β lactamase by nitrocefin disc and vancomycin resistance by agar dilution was determined in 150 enterococcal isolates, as per NCCLS guidelines. Only two species, Enterococcus faecalis (85.5%) and Enterococcus faecium (14.7%) were recovered, mostly from blood. Forty six percent showed HLAR. Multi drug resistance and concomitant resistance of HLAR strains to β lactams were quite high. None showed β lactamase activity or vancomycin resistance.
Genetic diversity and antimicrobial resistance of enterococcal isolates from Southern region of Brazil
d'Azevedo, Pedro Alves;Dias, Cícero Armídio Gomes;Teixeira, Lúcia Martins;
Revista do Instituto de Medicina Tropical de S?o Paulo , 2006, DOI: 10.1590/S0036-46652006000100003
Abstract: in the present study, a total of 455 enterococcal isolates, recovered from patients living in the city of porto alegre, state of rio grande do sul, brazil, during the period from july 1996 to june 1997, were identified to the species level by conventional biochemical and microbiological tests, and assayed for their susceptibilities to antimicrobial agents. the genetic diversity of antimicrobial resistant strains was evaluated by pulsed-field gel electrophoresis (pfge) analysis of smai restricted chromosomal dna. the most frequent species was enterococcus faecalis (92.8%). other species identified were: e. faecium (2.9%), e. gallinarum (1.5%), e. avium (1.1%), e. hirae (0.7%), e. casseliflavus (0.4%), e. durans (0.4%) and e. raffinosus (0.2%). the overall prevalence of isolates with high-level resistance (hlr) to aminoglycosides was 37.8%. hlr to gentamicin was found in 24.8%. no strains with acquired resistance to vancomycin were found. pfge analysis showed the predominance of clonal group a, comprising strains isolated from different clinical specimens obtained from patients in three hospitals. these results suggest intra and inter-hospital dissemination of one predominant clonal group of e. faecalis isolates with hlr to gentamicin in the hospitals included in this study.
Genetic diversity and antimicrobial resistance of enterococcal isolates from Southern region of Brazil  [cached]
d'Azevedo Pedro Alves,Dias Cícero Armídio Gomes,Teixeira Lúcia Martins
Revista do Instituto de Medicina Tropical de S?o Paulo , 2006,
Abstract: In the present study, a total of 455 enterococcal isolates, recovered from patients living in the city of Porto Alegre, State of Rio Grande do Sul, Brazil, during the period from July 1996 to June 1997, were identified to the species level by conventional biochemical and microbiological tests, and assayed for their susceptibilities to antimicrobial agents. The genetic diversity of antimicrobial resistant strains was evaluated by pulsed-field gel electrophoresis (PFGE) analysis of SmaI restricted chromosomal DNA. The most frequent species was Enterococcus faecalis (92.8%). Other species identified were: E. faecium (2.9%), E. gallinarum (1.5%), E. avium (1.1%), E. hirae (0.7%), E. casseliflavus (0.4%), E. durans (0.4%) and E. raffinosus (0.2%). The overall prevalence of isolates with high-level resistance (HLR) to aminoglycosides was 37.8%. HLR to gentamicin was found in 24.8%. No strains with acquired resistance to vancomycin were found. PFGE analysis showed the predominance of clonal group A, comprising strains isolated from different clinical specimens obtained from patients in three hospitals. These results suggest intra and inter-hospital dissemination of one predominant clonal group of E. faecalis isolates with HLR to gentamicin in the hospitals included in this study.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.