Molecular characterization of Staphylococcus aureus from outpatients in the Caribbean reveals the presence of pandemic clones

Staphylococcus aureus infections continue to pose a global public health problem. Frequently, this epidemic is driven by the successful spread of single S. aureus clones within a geographic region, but international travel has been recognized as a potential risk factor for S. aureus infections. To study the molecular epidemiology of S. aureus infections in the Caribbean, a major international tourist destination, we collected methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) isolates from community-onset infections in the Dominican Republic (n = 112) and Martinique (n = 143). Isolates were characterized by a combination of pulsed-field gel electrophoresis (PFGE), spa typing, and multilocus sequence typing (MLST) typing. In Martinique, MRSA infections (n = 56) were mainly caused by t304-ST8 strains (n = 44), whereas MSSA isolates were derived from genetically diverse backgrounds. Among MRSA strains (n = 22) from the Dominican Republic, ST5, ST30, and ST72 predominated, while ST30 t665-PVL+ (30/90) accounted for a substantial number of MSSA infections. Despite epidemiological differences in sample collections from both countries, a considerable number of MSSA infections (~10%) were caused by ST5 and ST398 isolates at each site. Further phylogenetic analysis suggests the presence of lineages shared by the two countries, followed by recent genetic diversification unique to each site. Our findings also imply the frequent import and exchange of international S. aureus strains in the Caribbean.     

Clinical features and treatment outcomes of vancomycin-intermediate <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (VISA) and heteroresistant vancomycin-intermediate <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (hVISA) in a tertiary care institution in Singapore

This retrospective case–control study was undertaken to review the clinical features associated with heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) and vancomycin-intermediate S. aureus (VISA) infections and the local impact they have on clinical outcome. Compared with vancomycin-susceptible S. aureus (n = 30), hVISA and VISA infections (n = 10) are found to be associated with a longer period of prior glycopeptide use (P = 0.01), bone/joint (P < 0.01) and prosthetic infections (P = 0.04), as well as treatment failure, as evidenced by longer bacteremic (P < 0.01) and culture positivity (P < 0.01) periods. This was observed to have resulted in longer hospital length of stay (P < 0.01) and total antibiotic therapy duration (P = 0.01). There was, however, no significant difference in the overall patient mortality or the hospitalization cost (P = 0.12) in both groups. Clinicians should be cognizant of the association between hVISA/VISA with high bacterial load deep-seated infections. We recommend targeted and even universal screening for hVISA/VISA in methicillin-resistant S. aureus (MRSA) infections.     

<Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis> skin and soft tissue infections: characterization of causative strains and clinical illness

Streptococcus pneumoniae is an uncommon cause of skin and soft tissue infections, yet the incidence and clinical significance of its isolation in samples of skin or soft tissues in unselected hospital samples is poorly understood. In the present study, a review was conducted of the records of all patients with skin and soft tissue infections due to S. pneumoniae at a university hospital between January 1994 and December 2005. The isolates were identified by standard methods and were serotyped, and susceptibility testing was performed by the broth microdilution method following the guidelines of the Clinical and Laboratory Standards Institute. During the study period, 3,201 isolates of S. pneumoniae were recovered from several sources. Of these, 69 (2.2%) were from skin and soft tissue samples (69 patients). Complete information could not be obtained for 13 patients. Of the 56 patients remaining, 36 (64.3%) were infected and fulfilled the inclusion criteria. The following types of infections were observed: surgical wound infection (n = 11), burn infection (n = 7), pyomyositis (n = 6), cellulitis (n = 4), perineal or scrotal abscess (n = 3), and other (n = 5). Thirty-one (86%) patients had a favorable outcome, and 5 (13.8%) patients died. Mortality was directly attributable to S. pneumoniae infection in three of the five fatal cases. Of the 39 S. pneumoniae isolates obtained (36 from skin and soft tissues, three from blood cultures), 58.9% were penicillin nonsusceptible, 7.7% were cefotaxime nonsusceptible, and 20.5% were erythromycin resistant. The most frequent serotypes were 3, 19, 11, and 23. Of the overall number of isolates of S. pneumoniae recovered in a general institution, 2.2% involved skin and soft tissues (of which 64% were clinically significant). Mortality due to pneumococcal skin and soft tissue infections was low. R. Pallarés, coordinator (e-mail: rpallares@bell.ub.es)     

Molecular characterisation of invasive <Emphasis Type="Italic">Streptococcus pyogenes</Emphasis> isolates from Hungary obtained in 2004 and 2005

Our aim was to characterise by molecular techniques group A streptococci isolated from invasive infections in Hungary in 2004–2005. Twenty-six nonduplicate invasive GAS isolates were selected and examined. The mortality rate proved high (52.3%) for those cases (n = 21) where data were available. Predominant emm types were emm1 (n = 13, 50%) and emm80 (n = 5, 19.2%), but other M types (emm4, emm28, emm66, emm81.1, emm82, emm84) were also identified. Eight different PFGE types were distinguished, and each emm type showed an individual PFGE pattern. Our results show that—similarly to results obtained in several other countries—emm type 1 strains predominate among invasive GAS isolates, and that emm 1 type strains recovered from severe streptococcal infections were associated with the presence of the speA gene. The rate for macrolide resistance proved low: only two isolates showed elevated MICs for erythromycin.     

High prevalence of ST121 in community-associated methicillin-susceptible Staphylococcus aureus lineages responsible for skin and soft tissue infections in Portuguese children

In order to evaluate the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Portugal, we analyzed a collection of 38 S. aureus isolates recovered from 30 children attending the pediatric emergency department of a central hospital in Lisbon due to skin and soft tissue infections. Molecular characterization identified seven clonal lineages among the 35 methicillin-susceptible S. aureus (MSSA) isolates, of which the major lineage PFGE A/t159/ST121 included 63% of the isolates. The three MRSA isolates belonged to the Pediatric clone PFGE D/t535/ST5-IV (n = 2) and to the European CA-MRSA clone PFGE G/t044/ST80-IVc (n = 1). All isolates harbored several virulence factors, namely, leukocidins. Panton–Valentine leukocidin (PVL) was produced by isolates from five MSSA lineages and by the ST80 MRSA. Of interest, this is the first reported isolation of CA-MRSA ST80 in Portugal.     

In vitro activity of fluoroquinolones against clinical isolates of Nocardia identified by partial 16S rRNA sequencing

Fluoroquinolones have several properties that make them potentially attractive candidates for the treatment of Nocardia infections, but information regarding their in vitro activity is limited. Minimum inhibitory concentrations (MIC) of five fluoroquinolones and other antimicrobials were determined by the reference broth dilution and E-test methods for 33 consecutive clinical isolates of Nocardia speciated by 16S rRNA gene sequences. The isolates included: Nocardia cyriacigeorgica (n = 6), N. nova (n = 8), N. farcinica (n = 8), N. brasiliensis (n = 3), N. asteroides (n = 4), and N. veterana (n = 4). MIC₅₀/MIC₉₀ results for ciprofloxacin, gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin by broth dilution were 32/32, 2/4, 1/4, 32/32, and 2/2 μg/ml, respectively. The MICs by broth dilution and E-test were within a two-fold doubling dilution for 94%, 97%, 97%, 100%, and 100% of isolates for ciprofloxacin, gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin, respectively. For ciprofloxacin, the E-test results showed either complete categorical agreement or minor error compared to the reference broth dilution method for 97% (32/33) of the isolates. For other fluoroquinolones, using Streptococcus pneumoniae breakpoints, 94% (124/132) of MIC results by E-test showed either complete agreement or minor error compared to the reference broth dilution method. Fluoroquinolones show variable in vitro activity against clinical isolates of Nocardia spp., and MICs determined by the E-test show reasonable agreement with those determined by the reference broth dilution method.     

Simultaneous species identification and detection of rifampicin resistance in staphylococci by sequencing of the <Emphasis Type="Italic">rpoB</Emphasis> gene

In recent years, coagulase-negative staphylococci (CoNS) have been increasingly recognised as causative agents of various infections, especially in immunocompromised patients and related to implanted foreign body materials. In this study, rpoB sequencing was used for simultaneous species identification and detection of rifampicin resistance in clinical staphylococci isolates. Forty-nine (96%) out of 51 isolates, representing 17 different Staphylococcus species according to the initial phenotypic species identification, were identified to the species level using rpoB sequencing. Furthermore, the two remaining isolates were Kocuria sp. and Corynebacterium sp. respectively, according to 16S rRNA sequencing. Comparison with the phenotypic diagnostics also revealed that 8 (16%) of the 49 isolates differed regarding identified species. Discrepant analysis confirmed the result of the rpoB sequencing for all except 2 of these isolates, which could not be distinguished as single species using 16S rRNA sequencing. Regarding detection of rifampicin resistance, isolates obtained pre- and post-treatment with rifampicin were examined. These isolates comprised S. aureus (7 patients) and S. lugdunensis (1 patient). Rifampicin resistance was mainly detected following short-term treatment with rifampicin in combination with isoxazolyl-penicillin, or long-term treatment with rifampicin and ciprofloxacin. Each rifampicin-resistant isolate displayed an identical rpoB sequence as their corresponding rifampicin-susceptible isolates except for one (n = 6) or two (n = 1) nonsynonymous single nucleotide polymorphisms, or insertion of one codon (n = 1). In conclusion, rpoB sequencing is a rapid, objective and accurate method of species identification and simultaneous detection of rifampicin resistance in staphylococci.     

Distribution of <Emphasis Type="Italic">emm</Emphasis> types in invasive and non-invasive group A and G streptococci

Our study describes the emm type distributions of invasive and non-invasive group A streptococci (GAS) and group G streptococci (GGS) strains in one of the biggest Health Districts in Finland. A total of 571 GAS or GGS were recovered from patients with invasive or non-invasive infections during a 1-year period in 2008–2009 in Pirkanmaa Health District in Finland. We describe here the emm type distributions of GAS and GGS collected from throat (n = 246), pus (n = 217), deep tissue (n = 56) and blood (n = 52). The most common emm types among GAS were emm77, emm1, emm28, emm89 and emm12. Among GGS, the most common emm types were stG480, stG643, stG6, stC6979 and stG485. Some emm types were found to associate with certain infection focus. In GAS, emm77 associated with pus isolates, whereas emm1 and emm12 were more frequent among throat isolates. In GGS, stG480 was more commonly found from throat isolates.     

Clinical evaluation of the Copan ESwab for methicillin-resistant Staphylococcus aureus detection and culture of wounds

The screening for and diagnosis of bacteriological infections often involves the collection and transportation of swab samples. The Copan ESwab was compared with the dry cotton Copan swab for methicillin-resistant Staphylococcus aureus (MRSA) screening (n = 200 paired samples) and with the Amies agar gel swab (Copan) for the sampling of burn and orthopaedic wounds (n = 203 paired samples) in terms of Gram staining and bacterial recovery. Gram stains performed with ESwab liquid showed significantly more Gram-negative rods, streptococci, Gram-positive cocci, Gram-positive rods, polymorphonuclear cells, lymphocytes and red blood cells than Gram stains from dry swabs. Bacterial recovery was significantly higher with ESwab (p < 0.01, for both MRSA screening and wounds, quantitative/semi-quantitative method). This lead to a slightly higher detection rate of MRSA (128 vs. 124 MRSA-positive ESwabs and dry swabs, respectively, p = 0.50) and a higher detection rate of coagulase-negative Staphylococcus spp. (44 isolates with ESwab vs. 29 with Amies gel swab, p = 0.001) and Enterococcus spp. (15 isolates with ESwab vs. 7 isolates with Amies gel swab, p = 0.005) with ESwab (quantitative method). We confirmed that ESwab has a high performance for Gram stains and a higher bacterial recovery than dry and Amies gel swabs when using clinical samples for MRSA screening and wound sampling.     

Prevalence of virulence-associated genotypes of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> and correlation with severity of gastric pathology in patients from western Sicily,Italy

In a bacterium like Helicobacter pylori, which is characterized by a recombinant population structure, the associated presence of genes encoding virulence factors might be considered an expression of a selective advantage conferred to strains with certain genotypes and, therefore, a potentially useful tool for predicting the clinical outcome of infections. However, differences in the geographical and ethnic prevalence of the H. pylori virulence-associated genotypes can affect their clinical predictive value and need to be considered in advance. In this study we carried out such an evaluation in a group of patients living in Sicily, the largest and most populous island in the Mediterranean Sea. cagA, vacA, babA2, hopQ, oipA, sabA, and hopZ were the H. pylori virulence-associated genes assayed; their presence, expression status or allelic homologs were detected in H. pylori DNA samples and/or isolated strains, obtained by gastric biopsy from 90 Sicilian patients with chronic gastritis, inactive (n = 37), active (n = 26), or active with peptic ulcer (n = 27). Genotypes cagA ⁺, vacAs1, vacAm1, babA2 ⁺, and hopQ I, I/II were identified in 51.8, 80.4, 35.2, 47.3, and 67.7% of the different samples respectively. Only these genotypes were associated with each other and with the active form of chronic gastritis, irrespective of the presence of a peptic ulcer. In our isolates their prevalence was more similar to values observed in the north of Italy and France than to those observed in Spain or other Mediterranean countries that are closer and climatically more similar to western Sicily.     

When the resistance gets clingy: Pseudomonas aeruginosa harboring metallo-β-lactamase gene shows high ability to produce biofilm

The ability to produce biofilm and the presence of metallo-β-lactamase (MBL) among Pseudomonas aeruginosa isolates were evaluated. A total of 91 isolates were recovered from sputa of patients with (CF, n = 44) and without (non-CF, n = 47) cystic fibrosis diagnosis. Seventy-nine (86.8%; 95% CI 78.3–92.3%) were biofilm producers. Interestingly, all isolates harboring MBL showed ability (most strong or moderate) to produce biofilm in vitro. We alert to an “overlapping of mechanisms” that together represent an even greater challenge for the treatment of pulmonary infections by P. aeruginosa.     

Detection of <Emphasis Type="Italic">Fasciola gigantica</Emphasis> infection in buffaloes by enzyme-linked immunosorbent assay

The process of isolation of the 27-kDa glycoprotein from the somatic antigen of Fasciola gigantica was standardized and the diagnostic potentiality was evaluated for the detection of bubaline fasciolosis by indirect enzyme-linked immunosorbent assay. Initially, the test was standardized using the sera from experimentally noninfected(n = 20) and infected (n = 5)animals. Further, the sensitivity and the specificity of the test were evaluated through the sera of buffaloes with different natural infections, i.e., F. gigantica (n = 8 animals), F. gigantica and Gastrothylax crumenifer(n = 15), F. gigantica and Gigantocotyle explanatum (n = 6), trematode infections other than F. gigantica (n = 9), only G. crumenifer (n = 36), only G. explanatum (n = 18), G. crumenifer and G. explanatum positive (n = 39), and PM negative (n = 102). All animals came from the slaughterhouses of Bareilly (Uttar Pradesh, India) and Patna (Bihar, India). The level of sensitivity observed in the present study was 81.0%, while 97–98% specificity against G. crumenifer, G. explanatum, or a mixed infection with both parasites was noted. The study showed F. gigantica prevalence rate of 18–20% in the buffaloes of the study area. Enzyme-linked immunosorbent assay with a 27-kDa glycoprotein could be a feasible diagnostic method for the early detection of bovine fasciolosis.     

Strong slime production is a marker of clinical significance in <Emphasis Type="Italic">Staphylococcus epidermidis</Emphasis> isolated from intravascular catheters

Biofilm production was assessed in 52 Staphylococcus epidermidis isolates from the catheters of 52 patients with catheter-related bloodstream infections (CR-BSI) and compared with 14 isolates from the skin of healthy volunteers by spectrophotometry. The isolates were classified as non- (G1), weak- (G2) or strong- (G3) slime producers based on optical density, and as producers and non-producers based on the results of the Congo red agar test. Differences (p = 0.012) in the proportion of G1, G2 and G3 among the isolates were found between catheter and healthy skin strains: there was a higher percentage of G1 types among the healthy skin strains (35.7 vs. 11.5%; p = 0.046) and a higher percentage of G3 types among the catheter isolates (44.2 vs. 0%; p = 0.001). No significant differences were found with the Congo red agar test. G3 is a phenotypic marker for CR-BSI.     

Differentiation of <Emphasis Type="Italic">Mycobacterium kansasii</Emphasis> infection from <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis> infection: comparison of clinical features,radiological appearance,and outcome

This retrospective study sought to systematically identify clinical and radiological features differentiating Mycobacterium kansasii from Mycobacterium tuberculosis infection. The sample included matched patients with a culture-positive diagnosis of M. tuberculosis infection (n = 121) or M. kansasii infection (n = 62) derived from the databases of two tuberculosis centers. Data on patient background and clinical features were collected, and chest radiographs were analyzed. Sixty percent of the M. kansasii group were native Israelis compared to 15% of the M. tuberculosis group (p = 0.0001). M. tuberculosis infection was associated with a higher rate of human immunodeficiency virus (HIV) infection (p = 0.03) and M. kansasii infection with a higher rate of lung disease (p = 0.0001). M. tuberculosis infection was characterized by a higher likelihood of bilateral disease (p = 0.005), pleural effusions, and lymphadenopathy (p = 0.006 and p = 0.001, respectively). There were ten deaths, all in the M. tuberculosis group. On multivariate logistic regression, the presence of chronic obstructive pulmonary disease and associated lung disease were significant predictors of M. kansasii infection. The findings show that there are group differences between the clinical features of the two infections. In the setting of pulmonary mycobacterial infection, the presence of coinfection with HIV, bilateral disease, pleural effusion, and lymphadenopathy make M. kansasii infection very unlikely.     

Comparison of Genotypes and Enterotoxin Genes Between Staphylococcus aureus Isolates from Blood and Nasal Colonizers in a Korean Hospital

In this study, we investigated the genetic background of 70 Staphylococcus aureus isolates (36 methicillin-resistant S. aureus [MRSA] and 34 methicillin-susceptible S. aureus [MSSA]) obtained from blood at a Korean tertiary-care hospital, using spa typing, multilocus sequence typing, and SCCmec typing. In addition, the prevalence of enterotoxin (sea, seb, sec, sed, see, seg, seh, sei, and sek), tst, and pvl genes among the samples was assessed via polymerase chain reaction, and the results were compared with those of 95 isolates of S. aureus obtained from nasal swabs. All MRSA isolates from blood, except one, belonged to three major clones: sequence type (ST)5-MRSA-II, ST72-MRSA-II (or IVA), and ST239-MRSA-III, among which ST5-MRSA-II was the predominant clone. The prevalence of enterotoxin genes in the S. aureus isolates obtained from blood differed significantly from those from the nasal swabs for the sea, seb, sec, and seh gene. In particular, the seb and sec genes were detected exclusively in the MRSA isolates of ST5 or spa-CC002, thereby suggesting the co-adaptation of virulence genes with the genetic background and their contribution to biological fitness.     

Predictors of mortality in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia: the role of empiric antibiotic therapy

The objective of this study was to evaluate prognostic factors and the influence of different empiric antibiotic therapies on outcome and mortality in a cohort of 100 inpatients with bacteraemia (84 cases nosocomial) caused by methicillin-resistant Staphylococcus aureus (MRSA). Patients were investigated by means of a standard protocol at a 944-bed hospital in the years 2000–2004. Empiric antibiotic therapies included vancomycin (n = 49), teicoplanin (n = 20), linezolid (n = 17), other antibiotics active in vitro (n = 7), and inactive antibiotics (n = 7). Overall mortality was 40% (12% among linezolid-treated patients; 46.3% among glycopeptide-treated patients). In bivariate analyses, the following factors were statistically associated with higher mortality: rapidly fatal underlying disease, altered mental status, metabolic acidosis, and acute severe clinical condition at the onset of bacteraemia; development of complications (septic shock, renal failure, and disseminated intravascular coagulopathy); empiric monotherapy with glycopeptides (vs combination therapy with an aminoglycoside); and inadequate empiric treatment. Empiric therapy with linezolid was associated with lower mortality. In multivariate analysis, risk factors associated with higher mortality included acute severity of illness (OR 7.49; 95%CI 1.19–25.3) and altered mental status (OR 4.83; 95%CI 1.22–19.15) at onset, complications (OR 3.42; 95%CI 1.02–17.46), and inappropriate empiric treatment (OR 7.6; 95%CI 1.87–31.14). In multivariate analysis limited to patients who received empiric therapy with either linezolid (n = 17) or glycopeptides (n = 69), linezolid was associated with greater rates of survival (OR 7.7; 95%CI 1.1–53) and microbiological eradication (OR 11.76; 95%CI 1.46–90.9) but not with fewer complications (OR 0.71; 95%CI 0.16–3.25). In conclusion, the main prognostic factors associated with mortality in patients with MRSA bacteraemia are complications, acute severe clinical condition at onset, and inappropriate empiric treatment. Empiric therapy with linezolid was associated with greater survival and more successful microbiological eradication but did not reduce complications.     

Extended-spectrum β-lactamase-producing Shigella strains in Israel, 2000–2004

Routine susceptibility testing of 5,616 Shigella isolates at the National Shigella Reference Centre in Israel over a 5-year period (2000–2004) revealed resistance to ceftriaxone in one strain of Shigella boydii 2 and in two strains each of Shigella flexneri 2a, S. flexneri 6, and Shigella sonnei. All seven isolates were confirmed as producers of extended-spectrum β-lactamase (ESBL) by the combination disk method, the Vitek 1 system, and a modification of the double-disk synergy test, which is based on the inhibitory properties of clavulanic acid, tazobactam, and sulbactam. Tazobactam had the strongest effect in all seven strains. Molecular characterization of the ESBLs identified CTX-M-type enzymes, consisting of the CTX-M-9 group (n = 3), CTX-M-3 (n = 2), CTX-M-39 (n = 1), and CTX-M-2 group (n = 1). Three of the strains also carried bla-_OXA genes and a bla-_TEM gene. Although the prevalence of ESBLs in this study was low, further research is needed on the spread and transfer of resistance genes, both in hospitals and in the community.     

<Emphasis Type="Italic">Chlamydia trachomatis</Emphasis> serovar distribution and other concurrent sexually transmitted infections in heterosexual men with urethritis in Italy

The distribution of Chlamydia trachomatis serovars among 157 heterosexual male patients with urethritis and the presence of coinfections with other sexually transmitted infections were studied. One hundred seventeen (74.5%) patients, with a mean age of 33.7 years, were Italians, whereas 40 (25.5%) were immigrants coming from eastern European countries, Africa, and South America. All the immigrants and 82 (70.0%) Italian patients reported sex with prostitutes. Out of 157 patients, 73 (46.5%) were found positive for C. trachomatis in urethral secretions and eight different C. trachomatis serovars were identified. The most common serovars were E (n = 18; 24.7%), D (n = 15; 20.5%), G (n = 14;19.2%), and F (n = 12; 16.4%). The sequencing data showed a high degree of conservation of the omp1 gene. Thirty-six (46.7%) out of the 73 C. trachomatis-positive patients were coinfected with another sexually transmitted infection. The most common coinfection was gonorrhoea detected in 22 (30.1%) patients, followed by condyloma in eight (8.2%) patients, syphilis in five (6.8%), and HIV in three (4.1%).     

Clonal spread of CC17 vancomycin-resistant Enterococcus faecium with multilocus sequence type 78 (ST78) and a novel ST444 in Taiwan

From May 2007 to January 2008, 30 isolates of vancomycin-resistant enterococci (VRE), including 29 Enterococcus faecium (96.7%) and 1 E. faecalis (3.3%) were obtained from various clinical specimens of 30 patients treated at a university hospital in Taiwan. Among these patients, 27 had VRE infections, including urinary tract infection (n = 16), bacteremia (n = 5), wound infection (n = 5), and central nervous system infection (n = 1). Three patients had VRE colonization. All of these isolates belonged to the vanA genotype with vancomycin minimum inhibitory concentrations of 64≥128 μg/ml. The isolate of E. faecalis had VanB phenotype-vanA genotype. All these isolates were susceptible to linezolid and were inhibited by tigecycline at 0.25 μg/ml. Multilocus sequence typing (MLST) analysis of the E. faecium isolates showed that 82.8% were ST78, which belongs to lineage C1. Transposon typing classified the 30 isolates of VRE into three types and most of the Tn1546-like elements contained an IS1251-like insertion sequence. Mating experiments showed that the vanA gene clusters were transferable at a frequency of about 10⁻⁶ to 10⁻⁷. Our findings indicate that nosocomial spread of VRE resulted from dissemination of lineage C1 E. faecium clones, including a novel E. faecium MLST type (ST444), and the horizontal transfer of Tn1546 elements among enterococci.