Global spread of vancomycin-resistant Enterococcus faecium from distinct nosocomial genetic complex.Vancomycin-resistant enterococci enterococci
bacteria in the genus Enterococcus. (VRE VRE
VRE Vancomycin-resistent enterococcus, see there ) have caused hospital outbreaks worldwide, and the vancomycin-resistance gene (vanA) has crossed genus boundaries to methicillin-resistant Staphylococcus aureus methicillin-resistant Staphylococcus aureus Methicillin-aminoglycoside resistant Staphylococcus aureus, MRSA An organism with multiple antibiotic resistances–eg, aminoglycosides, chloramphenicol, clindamycin, erythromycin, rifampin, tetracycline, . Spread of VRE, therefore, represents an immediate threat for patient care and creates a reservoir of mobile resistance genes for other, more virulent pathogens. Evolutionary genetics Evolutionary genetics is the broad field of studies that attempts to account for evolution in terms of changes in gene and genotype frequencies within populations and the processes that convert the variation with populations into more or less permanent variation between species. , population structure, and geographic distribution of 411 VRE and vancomycin-susceptible Enterococcus faecium Enterococcus faecium A nosocomial pathogen resistant to most antibiotics–eg, penicillin, teicoplanin, aminoglycosides, glycopeptides; ID of E faecium in a clinical specimen requires Pt isolation with barrier precautions. isolates, recovered from human and nonhuman sources and community and hospital reservoirs in 5 continents, identified a genetic lineage of E. faecium (complex-17) that has spread globally. This lineage is characterized by 1) ampicillin ampicillin (ăm'pĭsĭl`ĭn), a penicillin-type antibiotic that is effective against both gram-negative microorganisms and gram-positive microorganisms such as Escherichia coli. resistance, 2) a pathogenicity island, and 3) an association with hospital outbreaks. Complex-17 is an example of cumulative evolutionary processes that improved the relative fitness of bacteria in hospital environments. Preventing further spread of this epidemic E. faecium subpopulation sub·pop·u·la·tion
A part or subdivision of a population, especially one originating from some other population: microbial subpopulations.
Noun 1. is critical, and efforts should focus on the early disclosure of ampicillin-resistant complex-17 strains.
The emergence of vancomycin-resistant enterococci (VRE) followed a worst-case scenario for nosocomial nosocomial /noso·co·mi·al/ (nos?o-ko´me-il) pertaining to or originating in a hospital.
1. Of or relating to a hospital.
2. pathogens: the first VRE isolates that harbored the vanA transposon transposon /trans·po·son/ (trans-po´zon) a small mobile genetic (DNA) element that moves around the genome or to other genomes within the same cell, usually by copying itself to a second site but sometimes by splicing itself out of its were identified in 1987 in Europe (1,2), and within 10 years VRE represented >25% of enterococci associated with bloodstream infections in hospitalized patients in the United States (3).
Enterococci are normal inhabitants
The game is based loosely on the concepts from SameGame. of the gastrointestinal tract gastrointestinal tract
The part of the digestive system consisting of the stomach, small intestine, and large intestine.
Gastrointestinal tract of humans and animals. Two species cause most enterococcal infections, Enterococcus faecalis and E. faecium. The relative importance of E. faecium as a pathogen has increased with the occurrence of high-level resistance to multiple antimicrobial drugs, such as ampicillin and vancomycin vancomycin (văn'kōmī`sĭn), antibiotic resembling penicillin in the way it acts. It is derived from the bacterium Streptomyces orientalis, which was isolated from soil of India and Indonesia. (4). The rapid increase of vancomycin resistance compromises physicians' ability to treat infections caused by many of these strains because often no other antimicrobial drugs are available. The epidemiology of VRE infection differs between Europe and the United States. In Europe, VRE are frequently isolated from farm animals, which have been associated with the abundant use of avoparcin as a growth promoter in the agricultural industry, until it was banned in 1997 (5). The reported prevalence of VRE in hospitals has been low, but increasing rates (>10%) in stool and clinical samples were reported recently (6-9). In the United States, avoparcin was never approved for use in agriculture, and neither were any other glycopeptides; consequently, VRE have not been found in animals or healthy persons. However, nosocomial VRE infection and transmission have occurred much more frequently in the United States. Recent reports have documented, in hospitalized patients, horizontal transfer of the vanA gene from vancomycin-resistant E. faecalis to methicillin-resistant Staphylococcus aureus (MRSA MRSA Methicillin-resistant Staphylococcus aureus. See MARSA. ), creating MRSA with high-level resistance to vancomycin (10-13). Nosocomial spread of VRE may therefore create a reservoir of mobile resistance genes for other, more virulent, nosocomial pathogens. Without extensive control measures, large-scale emergence of vancomycin-resistant S. aureus The aureus (pl. aurei) was a gold coin of ancient Rome valued at 25 silver denarii. The aureus was regularly issued from the 1st century BC to the beginning of the 4th century AD, when it was replaced by the solidus. (VRSA VRSA Vancomycin-resistant Staphylococcus aureus. Cf Vancomycin-resistant enterococcus. ) may be the next stage in the global crisis of antimicrobial resistance.
The existence of VRE in different ecologic niches complicates the understanding of its epidemiology. Although previous molecular epidemiologic studies on limited numbers of strains suggested host specificity and overrepresentation of certain clones in hospital outbreaks (14,15), these studies did not elucidate the patterns of evolutionary descent among VRE. We determined the population structure of 411 VRE and vancomycin-susceptible E. faecium (VSE See DOS/VSE.
VSE - Virtual Storage Extended ) isolates by using multilocus sequence typing Multilocus sequence typing (MLST) is a technique in molecular biology for the typing of multiple loci. The procedure characterizes isolates of bacterial species using the DNA sequences of internal fragments of multiple (usually seven) housekeeping genes. (MLST MLST Multi Locus Sequence Typing
MLST Medical Logistics Support Team
MLST Mini Losi Super Truck (1/18th scale radio control vehicle) ), explored the evolutionary origin of epidemic isolates associated with documented hospital outbreaks and other isolates, and assessed the association with ampicillin resistance and the presence of a recently discovered putative pathogenicity island (PAI PAI plasminogen activator inhibitor.
PAI Plasminogen activator inhibitor, see there ) in E. faecium (16).
Materials and Methods
The strain collection included 5 categories of VRE and VSE: 1) 96 animal surveillance (bison, calves, cats, dogs, ostriches, poultry, pigs, rodents) isolates (43 VRE, 53 VSE) from 7 countries in Africa and Europe; 2) 57 epidemiologically unrelated community surveillance isolates (20 VRE, 37 VSE) from nonhospitalized persons from 7 countries in Australia and Europe; 3) 64 epidemiologically unrelated surveillance (fecal) isolates (45 VRE, 19 VSE) from hospitalized patients not linked to hospital outbreaks from 9 countries in Australia, Europe, and North and South America; 4) 162 epidemiologically unrelated hospital isolates (43 VRE, 118 VSE, 1 not determined) from clinical specimens (blood, pus pus, thick white or yellowish fluid that forms in areas of infection such as wounds and abscesses. It is constituted of decomposed body tissue, bacteria (or other micro-organisms that cause the infection), and certain white blood cells. , and urine) from 17 countries in Africa, Australia, Europe, and North and South America; and 5) 1 strain from each of 32 different documented hospital outbreaks (28 VRE, 4 VSE) in 10 countries in Australia, Europe, and North and South America (W. Grubb and D. Jonas, pers. comm.; 15,17-23).
We determined vancomycin susceptibilities for 410 isolates and ampicillin susceptibilities for 381 isolates by using standard agar dilution methods according to NCCLS NCCLS National Committee for Clinical Laboratory Standards guidelines. Isolates with MIC [greater than or equal to] 16 [micro]g/mL for ampicillin and [greater than or equal to] 8 [micro]g/mL for vancomycin were considered to be resistant. In total, 394 strains were screened for the esp gene with primer sets and amplification conditions described previously (24). Independent and combined effects of virulence and resistance markers on the abundance of complex-17 were estimated by using multiple logistic regression analysis (Stata 7.0, StataCorp LP, College Station, TX, USA).
MLST was carried out with a standard set of primers that amplify the 7 genes included in the E. faecium MLST scheme (14). Information on these loci loci
[L.] plural of locus.
loci Plural of locus, see there , the latest set of primers, amplification conditions, and details of all isolates are available on the MLST Web site (http://efaecium. mist.net).
The eBURST program was used to assess the genetic relationships of genotypes, to assign isolates to genetic complexes, and to study patterns of evolutionary descent of isolates within a complex (25). Complexes were identified by using the stringent (6/7 shared alleles) group definition with 1,000 bootstrap See boot.
(operating system, compiler) bootstrap - To load and initialise the operating system on a computer. Normally abbreviated to "boot". From the curious expression "to pull oneself up by one's bootstraps", one of the legendary feats of Baron von Munchhausen. replicates. The BLAND program was used to examine the relationship between pairwise allelic al·lele
One member of a pair or series of genes that occupy a specific position on a specific chromosome.
[German Allel, short for Allelomorph, allelomorph, from English differences and nucleotide sequence differences (26). If genetic diversity in E. faecium is mainly the result of accumulated point mutations, then recently diverged strains will have a high level of similarity in both their allelic profiles as well as in the nucleotide sequence of the nonidentical non·i·den·ti·cal
1. Not being the same; different.
2. Fraternal, as of twins. alleles, which results in a positive correlation between the number of nucleotide differences in nonidentical alleles and the number of allelic differences. However, such a trend will be absent when recombination recombination, process of "shuffling" of genes by which new combinations can be generated. In recombination through sexual reproduction, the offspring's complete set of genes differs from that of either parent, being rather a combination of genes from both parents. plays an important role in generating the genetic diversity, since nonidentical alleles of closely related isolates can differ at multiple nucleotide sites.
To assess the effect of recombination on the population structure of E. faecium in more detail, the topologies of the 7 MLST gene trees were compared by using the Shimodaira-Hasegawa test (27). Briefly, maximum likelihood trees for each MLST gene were obtained under a general time-reversible model, with a proportion of invariant (programming) invariant - A rule, such as the ordering of an ordered list or heap, that applies throughout the life of a data structure or procedure. Each change to the data structure must maintain the correctness of the invariant. sites and rate heterogeneity among sites assuming a discrete gamma distribution with 8 categories (GTR GTR Guitar
GTR Gamertag Radio (gaming community radio show)
GTR Guided Tissue Regeneration
GTR General Theory of Relativity (physics)
GTR Génie des Télécommunications et Réseaux +I+[GAMMA] model). PAU[P.sup.*] 4.0b10 was used to obtain the maximum likelihood trees by using a neighbor-joining starting tree followed by tree-bisection reconnection branch swapping (28). For a given gene, the Shimodaira-Hasegawa test compares the difference in log likelihoods of competing tree topologies. A null distribution of differences in log likelihoods was obtained by 1,000 replicates of nonparametric bootstrapping Bootstrapping
A procedure used to calculate the zero coupon yield curve from market figures.
Since the T-bills offered by the government are not available for every time period, the bootstrapping method is used to fill in the missing figures in order to derive the of reestimated log likelihoods. We conducted 107 Shimodaira-Hasegawa tests for each MLST gene by comparing the 7 MLST gene trees and 100 random trees separately generated for each of the MLST genes. In a clonal population, the different MLST housekeeping genes have similar tree topologies, but with recombination, the different genes may have different tree topologies that may fit random trees better.
Associations between ampicillin resistance, presence of a novel putative E. faecium PAI, and genetic clustering in complex-17 were described by linear logistic regression models: log odds = [b.sub.0] + [b.sub.1][x.sub.1] + [b.sub.2][x.sub.2] + [b.sub.3][x.sub.3] + ... + [b.sub.i][x.sub.i]. Log odds denotes the natural logarithm Natural logarithm
Logarithm to the base e (approximately 2.7183). of the proportion of samples from an epidemiologic group belonging to complex-17, [b.sub.i] denotes the parameter estimated by maximum likelihood methods and [x.sub.i] the level of exposure, e.g., 0 and 1 for ampicillin resistance, vancomycin resistance, and the presence of PAI and 0-4 for the epidemiologic source of isolates: animal surveillance, community surveillance, hospital surveillance, clinical sample, and hospital outbreak, respectively.
Identification of Clonal Lineages
MLST of 411 E. faecium isolates resulted in 175 different sequence types (ST). Clustering these types with the eBURST algorithm (25) showed 1 large complex of genetically related types. ST-22 was the primary founder; 3 minor complexes had ST-1, -69, and -94 as primary founders; 6 complexes had only 2 or 3 STs; and 57 singletons were not linked to the aforementioned complexes (Figure 1). Within complex-22, ST-17 represents an important secondary founder of a distinct branch designated complex-17.
[FIGURE 1 OMITTED]
Selective Advantage of the Successful Hospital-adapted Complex-17
In all, 142 of 411 isolates belonged to complex-17, with a gradual increase in proportion among animal isolates (1/96), human community isolates (3/57), human hospital surveillance isolates (15/64), and human clinical isolates (95/162), to hospital-outbreak isolates (28/32) (Table 1). Ampicillin resistance, presence of the E. faecium PAI (16), and genetic clustering in complex-17 were strongly associated (Table 2).
When controlling for individual and combined effects of ampicillin resistance, presence of PAI, and vancomycin resistance, we can show that 1) the loglinear assumption holds for all effect parameters, and linear models describe the observed frequencies without substantial loss of goodness of fit Goodness of fit means how well a statistical model fits a set of observations. Measures of goodness of fit typically summarize the discrepancy between observed values and the values expected under the model in question. Such measures can be used in statistical hypothesis testing, e. ; 2) individual genetic markers exert an independent and multiplicative mul·ti·pli·ca·tive
1. Tending to multiply or capable of multiplying or increasing.
2. Having to do with multiplication.
mul effect; and 3) all genetic markers combined explain [approximately equal] 48% of the category-specific abundance of complex-17 (Figure 2). The effect of vancomycin resistance did not increase the explanatory value of the model, owing to the fact that determinants for vancomycin resistance could be found in equal proportions within and outside of complex-17, likely a result of widespread horizontal transfer of vanA (Table 1). This finding suggests that the epidemiologic success of descendants of ST-17 that results in clinical infectious and hospital epidemics was at least partly related to antimicrobial resistance and the presence of putative virulence genes. The fact that 126 of 128 isolates of complex-17 were resistant to ampicillin and only 77 of 139 isolates of complex-17 contain PAI (Table 1) suggests that E. faecium acquired ampicillin resistance first, which resulted in a selective advantage in hospitals, followed by the acquisition of PAI, which further facilitated transmission.
[FIGURE 2 OMITTED]
Estimates of Recombination
To assess the effect of recombination on the population structure of E. faecium, we estimated whether single locus variants (SLVs) from the presumed founders of complex-1, -17, -22, -69, and -94 have arisen by point mutations or by recombination (Table 3). Of all allelic differences between ancestor-SLY pairs (n = 30), 22 (4 in complex-17) included >1 nucleotide, were found in multiple clonal complexes, and thus were most likely a result of recombination. Eight allelic differences (2 in complex-17) included only a single nucleotide change, were unique within the dataset, and thus were most likely a result of mutation. Therefore, most alleles of SLVs in complex-17 and in the other complexes have arisen by recombination in the initial stages of diversification rather than by de novo [Latin, Anew.] A second time; afresh. A trial or a hearing that is ordered by an appellate court that has reviewed the record of a hearing in a lower court and sent the matter back to the original court for a new trial, as if it had not been previously heard nor decided. point mutation. An important role for recombination in genetic diversification in E. faecium was confirmed by the lack of a positive trend between the number of nucleotide differences in nonidentical alleles and the number of allelic differences (Figure 3) (26). The finding of high average numbers ([greater than or equal to] 4) of nucleotide differences in the nonidentical alleles of SLVs in the total E. faecium population as well as in complex-17 also points towards frequent recombination.
[FIGURE 3 OMITTED]
The degree of phylogenetic phy·lo·ge·net·ic
1. Of or relating to phylogeny or phylogenetics.
2. Relating to or based on evolutionary development or history. congruence con·gru·ence
a. Agreement, harmony, conformity, or correspondence.
b. An instance of this: "What an extraordinary congruence of genius and era" between the 7 MLST genes was examined in a set of 24 diverse STs. These 24 STs were separated from each other by a linkage distance of >0.4 on a UPGMA UPGMA Unweighted Pair Group Method, Arithmetic Mean (unweighted pair-group method with arithmetic mean (mathematics) arithmetic mean - The mean of a list of N numbers calculated by dividing their sum by N. The arithmetic mean is appropriate for sets of numbers that are added together or that form an arithmetic series. ) tree constructed from the pairwise comparisons of their allelic profiles (data not shown) and included the primary founders of CC1 (ST1), CC22 (ST22), CC69 (ST69), and CC94 (ST94); secondary founders of important subgroups complex-5 (ST5) and complex-17 (ST17); 1 ST (ST76) belonging to a small complex of 3 STs; and 17 singletons (STs 15, 38, 39, 54, 67, 74, 83, 84, 89, 96, 98, 99, 101, 107, 118, 142, 163). The results of the congruence analysis presented in Table 4 show that 25 (60%) of 42 of the pairwise comparisons of the 7 MLST loci were incongruent in·con·gru·ent
1. Not congruent.
in·congru·ence n. . Of the 7 genes, atpA is the most incongruent. This analysis confirms that recombination played a substantial role in the evolution of E. faecium.
Nosocomial VRE, which rapidly emerged in the United States in the 1990s after their initial discovery in Europe, are found in increasing rates in hospitals in Europe Lists of hospitals for each country in Europe.
The >400 strains analyzed in this study were selected from a large representative collection of 2,000 E. faecium isolates. A wide variety of sources were used as selection criteria: hospital-associated outbreaks; clinical samples and stool samples from hospitalized patients, healthy persons, and animals; and a wide geographic distribution (21 countries on 5 continents).
Complex-17 probably evolved from the primary E. faecium ancestor ST-22 through a combination of mutation and recombination. The following observations suggest that recombination has been especially important in the genetic diversification of the E. faecium population: 1) within clonal complexes, most SLVs (73%) have arisen by recombination rather than point mutations; 2) no positive correlation exists between the degree of allelic diversity and the number of nucleotide differences in nonidentical alleles; and 3) most (60%) of the comparisons of MLST gene tree topologies were incongruent.
Exploitation of a novel ecologic niche as hospital settings by E. faecium ST-17 often starts with adaptive changes (31). On the basis of our findings, we postulate postulate: see axiom. that ST-17 acquired ampicillin resistance and a novel putative PAI. This amplifying selective process in which variants with a selective advantage can more easily acquire additional adaptive mechanisms has been called "genetic capitalism" (32). After successfully exploiting the hospital environment, ST-17 increased in frequency to become the dominant clone. Genetic diversification over time finally resulted in a meroclone, complex-17, of highly related genotypes, fully adapted as a nosocomial pathogen, that has spread globally (Figure 4). In addition, E. faecium STs, predominantly ST-78, belonging to complex-17, have recently also been found in the Republic of South Korea (K.S. Ko and J.-H. Song, pers. comm.). Considering the short period in which multiresistant E. faecium emerged as a nosocomial pathogen (33), complex-17 represents the first globally dispersed nosocomial-adapted clonal lineage. Despite the frequency of recombination events, clonal complex-17 is still detectable within the E. faecium population, which suggests that the emergence of this complex is relatively recent.
[FIGURE 4 OMITTED]
The existence of epidemic clones, even in recombining populations, is also seen in other bacterial species (34,35). However, the evolution of a single epidemic and clinically relevant genetic complex, as seen with E. faecium, differs from the evolution of other gram-positive pathogens like Streptococcus pneumoniae Streptococcus pneu·mo·ni·ae
Streptococcus pneumoniae Microbiology A pathogenic streptococcus with 90 serotypes associated with pneumonia, bacteremia, meningitis Transmission Person to person Incidence and Staphylococcus aureus Staphylococcus au·re·us
A bacterium that causes furunculosis, pyemia, osteomyelitis, suppuration of wounds, and food poisoning.
Staphylococcus aureus Staphylococcus pyogenes . In S. pneumoniae, pandemic pandemic /pan·dem·ic/ (pan-dem´ik)
1. a widespread epidemic of a disease.
2. widely epidemic.
Epidemic over a wide geographic area.
n. clones such as ST81. ST90, and ST156 represent major invasive and multidrug-resistant isolates that have spread globally (36). The allelic profiles of these clones, however, are highly diverse, which suggests that they are genetically unrelated and do not constitute a single genetic lineage, as does E. faecium. Furthermore, the serotype serotype /se·ro·type/ (ser´o-tip) the type of a microorganism determined by its constituent antigens; a taxonomic subdivision based thereon.
v. orS. pneumoniae seems a more important marker of invasiveness than the overall genotype (37). In S. aureus isolates, major pandemic MRSA clones that are responsible for most hospital-acquired infections Hospital-Acquired Infections Definition
A hospital-acquired infection is usually one that first appears three days after a patient is admitted to a hospital or other health care facility. are found in multiple genetically unrelated lineages, though most previously identified pandemic clones are found in clonal complex 8 (38,39). Therefore, the genetic diversity of major epidemic clones as seen in S. pneumoniae or S. aureus may not have yet emerged in E. faecium epidemic populations.
Stress-inducing conditions in hospitals, such as antimicrobial drug use, may have favored the selection of an enterococcal subpopulation, complex-17, with enhanced antibacterial antibacterial /an·ti·bac·te·ri·al/ (-bak-ter´e-al) destroying or suppressing growth or reproduction of bacteria; also, an agent that does this.
adj. resistance, virulence, and ability to spread. Whether reducing antimicrobial selection pressure in hospitals will reestablish a susceptible and less transmissible transmissible /trans·mis·si·ble/ (trans-mis´i-b'l) capable of being transmitted.
Capable of being conveyed from one person to another. enterococcal population is unknown and will at least partly depend on the relative fitness costs of sustaining antimicrobial resistance and virulence determinants in E. faecium. Furthermore, the hospital-adapted complex-17 has rapidly spread globally during the last 2 decades. Subsequent acquisition of vanA- or vanB- containing trans-posons by horizontal gene transfer “HGT” redirects here. For other uses, see HGT (disambiguation).
Horizontal gene transfer (HGT), also Lateral gene transfer (LGT), is any process in which an organism transfers genetic material to another cell that is not its offspring. resulted in VRE with pandemic potential. Rapid diagnosis of complex-17 strains based on multiple locus variable number of tandem repeat analysis (MLVA MLVA Micro Light Valve Array
MLVA Multi-locus VNTR Analysis
MLVA Multiple VNTR Locus Analysis ) may help control its spread (40). Whether this effort will be successful depends on the level of complex-17 endemicity in the hospital. In many European countries, a relatively large community reservoir of VRE exists, a result of the massive use of the antimicrobial drug avoparcin as a growth promoter, while in general the prevalence of hospital-adapted (complex-17) VRE is much lower. In such a setting, hospital transmission of isolates belonging to complex-17 can be halted by using a fast genotyping scheme like MLVA to discriminate between hospital-adapted (complex-17) and community E. faecium strains followed by strict infection control measures. The combination of infection control measures plus genotyping controlled an outbreak of VRE in a Dutch hospital (41).
Establishing nosocomial co-endemicity of VRE and MRSA will facilitate the horizontal transfer of vanA- or vanB- containing transposons Transposons
Types of transposable elements which comprise large discrete segments of deoxyribonucleic acid (DNA) capable of moving from one chromosome site to a new location. , transforming MRSA into VRSA, with implications for patient care. Until now, 3 sporadic cases of vanA-induced VRSA have been reported in the United States in 2002 and 2004. Spread of multidrug-resistant E. faecium strains and their resistance genes will have serious implications for health care, and control efforts should focus on early detection of E. faecium isolates belonging to complex-17.
Table 1. Frequency of ampicillin and glycopeptide resistance, the presence of the pathogenicity island (PAI), and log odds of all complex-17 and non-complex-17 Genetic and phenotypic features * Other Complex-17 ([dagger]) Complex-17 Epidemiologic source AmR AmS AmR AmS PAI+ PAI- Animal 1 0 2 93 0 1 surveillance (n = 96), % Community 0 0 1 46 3 0 surveillance (n = 57), % Hospital 14 0 7 40 7 8 surveillance (n = 64), % Clinical 85 2 13 47 47 47 (n = 162), % Hospital 26 0 3 1 20 6 outbreak (n = 32), % Genetic and phenotypic features * Other Other ([dagger]) Complex-17 ([dagger]) Epidemiologic source PAI+ PAI- VanR VanS VanR VanS Animal 0 94 0 1 43 52 surveillance (n = 96), % Community 0 47 3 0 17 37 surveillance (n = 57), % Hospital 0 49 13 2 32 17 surveillance (n = 64), % Clinical 4 57 21 73 22 45 (n = 162), % Hospital 3 1 24 4 4 0 outbreak (n = 32), % Other Log Epidemiologic Complex-17 ([dagger]) odds source ([double dagger]) ([double dagger]) ([section]) Animal 1  95  -4.55 surveillance (n = 96), % Community 3  54  -2.89 surveillance (n = 57), % Hospital 15  49  -1.18 surveillance (n = 64), % Clinical 95  67 [51 0.35 (n = 162), % Hospital 28  4 [121 1.95 outbreak (n = 32), % * Ampicillin resistant (AmR) or susceptible (AmS) not determined in 30 isolates, PAI present (PAI+) or absent (PA-) not determined in 17 isolates, vancomycin resistant (VanR) or susceptible (Vans) not determined in 1 isolate. ([dagger]) Not belonging to complex-17. ([double dagger]) Numbers in brackets refer to the percentage of isolates that belong to the complex. ([section]) The natural logarithm of the proportion of samples from an epidemiologic source belonging to complex-17. Table 2. Parameter estimates by using a logistic regression model * Parameter estimates Regression lines [b.sub.0] [b.sub.amp] [b.sub.PAI] Complex-17 crude -4.44 0 0 Corrected for amp -6.61 5.38 0 Corrected for PAI -6.29 5.08 1.06 Corrected for gly -6.07 5.12 1.01 Parameter estimates Regression lines [b.sub.gly] [b.sub.epi] p value Complex-17 crude 0 1.6 0.000 Corrected for amp 0 1 0.000 Corrected for PAI 0 0.84 0.038 Corrected for gly -0.45 0.83 0.316 * Amp, ampicillin resistance; PAI, presence of the Enterococcus faecium pathogenicity island, gly, glycopeptide resistance; epi, epidemiologic source (animal surveillance, community surveillance, hospital surveillance, clinical sample, hospital outbreak). Table 3. Variant alleles of single locus variants (SLVs) within 5 genetic complexes * Ancestral ST of ancestor ST of SLV Variant locus allele 17 64 atpA 1 17 117 atpA 1 17 78 atpA 1 17 16 ddl 1 17 63 purK 1 17 174 purK 1 22 32 atpA 2 22 21 atpA 2 22 92 atpA 2 22 71 atpA 2 22 135 atpA 2 22 159 atpA 2 22 113 atpA 2 22 55 ddl 3 22 111 gdh 1 22 24 purK 2 22 136 purK 2 22 33 pstS 1 22 23 adk 1 1 43 atpA 8 1 41 purK 7 1 2 gyd 1 1 3 pstS 1 94 40 atpA 13 94 60 gyd 6 94 61 pstS 10 94 178 pstS 10 69 46 atpA 9 69 161 atpA 9 69 47 adk 6 No. nucleotide differences (amino ST of ancestor SLV allele acid change) 17 7 4 17 9 20 17 15 22 17 2 1 17 21 1 (C-Y) ([dagger]) 17 29 1t 22 3 2 22 9 18 22 5 19 22 15 20 22 27 18 22 30 1 ([dagger]) 22 26 19 22 1 6 22 6 1 22 7 3 22 26 1 (H-Y) ([dagger]) 22 5 1 (L-V) ([dagger]) 22 7 1 ([dagger]) 1 3 16 1 3 4 1 9 1 (Y-H) ([dagger]) 1 12 1 (Y-N) ([dagger]) 94 10 3 94 11 1 94 17 4 94 27 2 69 5 1 69 3 16 69 5 4 * Genetic complexes 1, 17, 22, 69, and 94 were included in this analysis. ST, sequence type, C, cysteine, Y, tyrosine; H, histidine; L, leucine; V, valine; N, asparagine. ([dagger]) Single nucleotide changes that are unique in the dataset and thus are due to mutation. Table 4. Summary of gene congruence analysis No. incongruence Random trees Gene genes by SH test * ([dagger]) adk 1 (atpA) 8 (atpA) atpA 6 (adk, ddl, gdh, gyd, pstS, purK) 76 (adk) ddl 6 (adk, atpA, gdh, gyd, pstS, purK) 8 (atpA) gdh 1 (atpA) 1 (atpA) gyd 2 (adk, atpA) 0 (atpA) pstS 6 (adk, atpA, ddl, gdh, gyd, purK) 3 (atpA) purK 3 (atpA, adk, gyd) 1 (atpA) * Number of incongruent genes at the p<0.05 level based on a Shimodaira-Hasegawa (SH) test of tree topologies. The incongruent genes are in parentheses. ([dagger]) Number of random tree topologies out of 100 random trees that are better fit to the gene tree from the most incongruent multilocus sequence typing (MLST) gene. The most incongruent MLST gene is given in parentheses.
We thank B. Blomberg, A. Sundsfjord, A. van Belkum, D. Tribe, E. de Leener, W. Grubb, D. Jonas, M.G. Bonora, R.C. Zanella, L. Baldassarri, N. Shankar, N. Woodford, M. Soltani, S.C. Mohn, R. Jureen, and K. Borgen for providing E. faecium strains; N. Shankar, M. Gilmore, J. van Embden, B. Levin, and W. Jansen for critical reading of the manuscript; and D. Aanensen and B. Spratt for hosting the E. faecium MLST database (www.mlst.net) at Imperial College London History
Imperial College was founded in 1907, with the merger of the City and Guilds College, the Royal School of Mines and the Royal College of Science (all of which had been founded between 1845 and 1878) with these entities continuing to exist as "constituent colleges". .
Funding for this study was provided by University Medical Center Utrecht The Universitary Medical Center Utrecht (Dutch: Universitair Medisch Centrum Utrecht) or UMCU is the main hospital of the city of Utrecht. It is affiliated with the Universiteit Utrecht. and the National Institute for Public Health and the Environment, the Netherlands. The funding sources had no role in the selection, design, or reporting of this study.
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(2.) Uttley AH, Collins CH, Naidoo J, George RC. Vancomycin-resistant enterococci. Lancet. 1988;1:57-8.
(3.) Centers for Disease Control and Prevention Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center. . National nosocomial infections Nosocomial infections
Infections that were not present before the patient came to a hospital, but were acquired by a patient while in the hospital.
Mentioned in: Enterobacterial Infections, Staphylococcal Infections surveillance (NNIS NNIS National Nosocomial Infection Surveillance System ) system report, data summary from January 1992-June 2001, issued August 2001. Am J Infect Control. 2001;29:404-21.
(4.) Iwen PC, Kelly DM, Linder J, Hinrichs SH, Dominguez EA, Rupp ME, et al. Change in prevalence and antibiotic resistance antibiotic resistance,
n the ability of certain strains of microorganisms to develop resistance to antibiotics.
antibiotic resistance of Enterococcus enterococcus /en·tero·coc·cus/ (en?ter-o-kok´us) pl. enterococ´ci an organism belonging to the genus Enterococcus.
Enterococcus /En·tero·coc·cus/ ( species isolated from blood cultures over an 8-year period. Antimicrob Agents Chemother. 1997;41:494-5.
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(6.) Bouchillon SK, Johnson BM, Hoban DJ, Johnson JL, Dowzicky MJ, Wu DH, et al. Determining incidence of extended spectrum beta-lactamase producing Enterobacteriaceae, vancomycin-resistant Enterococcus vancomycin-resistant enterococcus Infectious disease An enterococcus, primarily Enterococcus faecium, resistant to most antibiotics, including aminoglycosides and vancomycin, once a 'last-resort' agent; VRE is primarily nosocomial, in long faecium and methicillin-resistant Staphylococcus aureus in 38 centres from 17 countries: the PEARLS PEARLS Protection, Effective Financial Structure, Asset Quality, Rates of Return and Costs, Liquidity and Signs of Growth (credit) study 2001-2002. Int J Antimicrob Agents. 2004;24:119-24.
(7.) European Antimicrobial Resistance Surveillance System (EARSS EARSS European Antimicrobial Resistance Surveillance System ). EARSS annual report 2003. [cited 2005 Jan 17]. Available from http://www.earss.rivm.nl/PAGINA/DOC/EARSS%20annual%20rep ort.2003.pdf
(8.) Goossens H, Jabes D, Rossi R, Lammens C, Privitera G, Courvalin P. European survey of vancomycin-resistant enterococci in at-risk hospital wards and in vitro in vitro /in vi·tro/ (in ve´tro) [L.] within a glass; observable in a test tube; in an artificial environment.
In an artificial environment outside a living organism. susceptibility testing of ramoplanin against these isolates. J Antimicrob Chemother. 2003;51(Suppl 3):iii5-12.
(9.) Jones ME, Draghi DC, Thornsberry C, Karlowsky JA, Sahm DF, Wenzel RP. Emerging resistance among bacterial pathogens in the intensive care unit--a European and North American North American
named after North America.
North American blastomycosis
see North American blastomycosis.
North American cattle tick
see boophilusannulatus. Surveillance study (2000-2002). Ann Clin Microbiol Antimicrob. 2004;3:14.
(10.) Centers for Disease Control and Prevention. Vancomycin-resistant Staphylococcus staphylococcus (stăf'ələkŏk`əs), any of the pathogenic bacteria, parasitic to humans, that belong to the genus Staphylococcus. The spherical bacterial cells (cocci) typically occur in irregular clusters [Gr. aureus--New York, 2004. MMWR MMWR Morbidity & Mortality Weekly Report Epidemiology A news bulletin published by the CDC, which provides epidemiologic data–eg, statistics on the incidence of AIDS, rabies, rubella, STDs and other communicable diseases, causes of mortality–eg, Morb Mortal Wkly Rep. 2004;53:322-3.
(11.) Chang S, Sievert sie·vert
Abbr. Sv A unit of ionizing radiation absorbed dose equivalent in the International System of Units, obtained as a product of the absorbed dose measure in grays and a dimensionless factor, stipulated by the International DM, Hageman JC, Boulton ML, Tenover FC, Downes FP, et al. Infection with vancomycin-resistant Staphylococcus aureus vancomycin-resistant Staphylococcus aureus VRSA Infectious disease A long anticipated bacterium first identified in a clinical specimen in mid-2002; the isolate was susceptible to chloramphenicol, linezolid, quinupristin-dalfopristin, T-S. containing the vanA resistance gene. N Engl J Med. 2003;348:1342-7.
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(13.) Weigel LM, Clewell DB, Gill SR, Clark NC, McDougal LK, Flannagan SE, et al. Genetic analysis of a high-level vancomycin-resistant isolate of Staphylococcus aureus. Science. 2003;302:1569-71.
(14.) Homan WL, Tribe D, Poznanski S, Li M, Hogg G, Spalburg E, et al. Multilocus sequence typing scheme for Enterococcus faecium. J Clin Microbiol. 2002;40:1963-71.
(15.) Willems RJL RJL Barndoor Skate (FAO fish species code)
RJL Remus John Lupin (fictional character) , Top J, van den Braak N, van Belkum A, Endtz H, Mevius D, et al. Host specificity of vancomycin-resistant Enterococcus faecium. J Infect Dis. 2000;182:816-23.
(16.) Leavis H, Top J, Shankar N, Borgen K, Bonten M, van Embden J, et al. A novel putative enterococcal pathogenicity island linked to the esp virulence gene of Enterococcus faecium and associated with epidemicity. J Bacteriol. 2004;186:672-82.
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(18.) Bonora MG, Ligozzi M, de Fatima M, Bragagnolo L, Goglio A, Guazzotti GC, et al. Vancomycin-resistant Enterococcus faecium isolates causing hospital outbreaks in northern Italy belong to the multilocus sequence typing C1 lineage. Microb Drug Resist. 2004;10:114-23.
(19.) Jureen R, Top J, Mohn SC, Harthug S, Langeland N, Willems RJL. Molecular characterization of ampicillin-resistant Enterococcus faecium isolates from hospitalized patients in Norway. J Clin Microbiol. 2003;41:2330-6.
(20.) Routsi C, Platsouka E, Willems RJ, Bonten MJ, Paniara O, Saroglou G, et al. Detection of enterococcal surface protein gene (esp) and amplified fragment length polymorphism Amplified fragment length polymorphism PCR, or "AFLP-PCR" (often AFLP), is a tool used in the study of genetics and in the practice of genetic engineering.
Amplified Fragment Length Polymorphism (AFLP typing of glycopeptide-resistant Enterococcus faecium during its emergence in a Greek intensive care unit. J Clin Microbiol. 2003;41:5742-6.
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(22.) Willems RJ, Homan W, Top J, van Santen-Verheuvel M, Tribe D. Manzioros X, et al. Variant esp gene as a marker of a distinct genetic lineage of vancomycin-resistant Enterococcus faecium spreading in hospitals. Lancet. 2001;357:853-5.
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(28.) Swofford DL. PAUP PAUP Phylogenetic Analysis Using Parsimony *: phylogenetic analysis using parsimony par·si·mo·ny
1. Unusual or excessive frugality; extreme economy or stinginess.
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(30.) Taneja N, Rani ra·ni also ra·nee
n. pl. ra·nis also ra·nees
1. The wife of a rajah.
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Evolution resulting from a succession of relatively small genetic variations that often cause the formation of new subspecies. of Neisseria meningitidis Neisseria men·in·git·i·dis
The bacteria that is the causative agent of cerebrospinal meningitis; meningococcus.
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Rob J.L. Willems, * Janetta Top, * Marga Marga can refer to:
* University Medical Center Utrecht, Utrecht, the Netherlands; ([dagger]) National Institute for Public Health and the Environment, Bilthoven, the Netherlands, ([double dagger) New York Medical College New York Medical College is a center for graduate medical education located in Westchester County, a suburb half an hour north of New York City. This private university comprises the School of Medicine, which grants the M.D. , Valhalla, New York Valhalla is a hamlet and census-designated place (CDP) located in the town of Mount Pleasant in Westchester County, New York, United States. The population was 5,379 at the 2000 census. , USA; and ([section]) Hospital Ramon y Cajal Ra·mòn y Ca·jal , Santiago 1852-1934.
Spanish histologist. He shared a 1906 Nobel Prize for research on the nervous system. , Madrid, Spain
Dr. Willems began this research at the National Institute for Public Health and the Environment and continued at the University Medical Center Utrecht, where he is currently working. His research interests are the molecular epidemiology molecular epidemiology Molecular medicine An evolving field that combines the tools of standard epidemiology–case studies, questionnaires and monitoring of exposure to external factors with the tools of molecular biology–eg, restriction endonucleases, , population structure, and genetic evolution of multidrug-resistant nosocomial pathogens.
Address for correspondence: Rob J.L. Willems, Eijkman-Winkler Institute for Microbiology, Infectious Diseases and Inflammation, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, the Netherlands: fax: 31-30-254-1176; email: r.willems@ digd.azu.nl