Ampicillin-resistant E. Faecium Research Articles

Detection of vancomycin-resistant Enterococcus faecium hospital-adapted lineages in municipal wastewater treatment plants indicates widespread distribution and release into the environment.

Vancomycin-resistant Enterococcus faecium (VREfm) is a leading cause of healthcare-associated infection. Reservoirs of VREfm are largely assumed to be nosocomial although there is a paucity of data on alternative sources. Here, we describe an integrated epidemiological and genomic analysis of E. faecium associated with bloodstream infection and isolated from wastewater. Treated and untreated wastewater from 20 municipal treatment plants in the East of England, United Kingdom was obtained and cultured to isolate E. faecium, ampicillin-resistant E. faecium (AREfm), and VREfm. VREfm was isolated from all 20 treatment plants and was released into the environment by 17/20 plants, the exceptions using terminal ultraviolet light disinfection. Median log10 counts of AREfm and VREfm in untreated wastewater from 10 plants in direct receipt of hospital sewage were significantly higher than 10 plants that were not. We sequenced and compared the genomes of 423 isolates from wastewater with 187 isolates associated with bloodstream infection at five hospitals in the East of England. Among 481 E. faecium isolates belonging to the hospital-adapted clade, we observed genetic intermixing between wastewater and bloodstream infection, with highly related isolates shared between a major teaching hospital in the East of England and 9/20 plants. We detected 28 antibiotic resistance genes in the hospital-adapted clade, of which 23 were represented in bloodstream, hospital sewage, and municipal wastewater isolates. We conclude that our findings are consistent with widespread distribution of hospital-adapted VREfm beyond acute healthcare settings with extensive release of VREfm into the environment in the East of England.

Occurrence of ampicillin-resistant Enterococcus faecium carrying esp gene in pet animals: An upcoming threat for pet lovers.

This study was carried out to investigate oral colonisation by Enterococcus faecalis and Enterococcus faecium in pet dogs and cats, with special reference to antibiotic resistance. Oral swabs were collected from 63 pet dogs and 57 pet cats with no known history of hospitalisation. All samples were enriched in Kenner Fecal (KF) broth before being cultured on KF agar to isolate enterococci. E. faecalis and E. faecium were identified by biochemical and molecular techniques. Antimicrobial resistance was determined by the disk diffusion method, and ampicillin-resistant strains were further examined by PCR to detect the esp gene. Oral prevalence rates of E. faecalis among pet dogs and cats were 3.2% and 5.3%, respectively, whilst those for E. faecium were 22.2% and 15.8%, respectively. None of the isolated enterococci were resistant to vancomycin. However, ampicillin-resistant E. faecium (AREfm) was detected in the examined dogs and cats at rates of 14.3% and 5.3%, respectively. Moreover, among the isolated enterococci, six isolates showed multidrug resistance (all AREfm). Whilst the esp gene was detected in only two of nine canine AREfm isolates (multidrug-resistant strains), none of feline AREfm isolates harboured esp. The occurrence of AREfm and the esp gene among oral isolates from pet dogs and cats represents a great public health hazard for pet owners and highlights possible zoonotic transmission of such a nosocomial pathogen outside healthcare facilities.

Screening municipal wastewater effluent and surface water used for drinking water production for the presence of ampicillin and vancomycin resistant enterococci.

The emergence of clinical enterococcal isolates that are resistant to both ampicillin and vancomycin is a cause of great concern, as therapeutic alternatives for the treatment of infections caused by such organisms are becoming limited. Aquatic environments could play a role in the dissemination of antibiotic resistant enterococci. This study investigated the presence of ampicillin and vancomycin resistant enterococci in the treated effluent of six wastewater treatment plants (WWTPs) and in surface water used as a source for drinking water production in the Netherlands. Membrane filtration in combination with selective media with ampicillin or vancomycin was applied to determine the presence of ampicillin resistant Enterococcus (ARE) and vancomycin resistant Enterococcus (VRE) species. Ampicillin resistant Enterococcus faecium (minimal inhibitory concentration (MIC) >16μg/mL; n=1033) was observed in all studied WWTP effluents. In surface water used for drinking water production (intake locations), no ARE or VRE were observed. At both types of location, intrinsic vancomycin resistant Pediococcus spp., Leuconostoc spp. and Lactobacillus spp. were isolated with the vancomycin medium. The ampicillin resistant E. faecium (AREfm) isolates (n=113) did not contain the vanA or vanB gene, but MIC testing for vancomycin showed intermediate vancomycin resistance (2-8μgmL(-1)) to occur in these AREfm strains. This study documents the discharge of ampicillin resistant E. faecium strains with intermediate vancomycin resistance by the WWTPs into the surface water, but no presence of these strains downstream at intake locations for drinking water production.

Emergence and Long-Lasting Persistence of Linezolid-ResistantEnterococcus faecium-ST117 in an Oncohematologic Patient After a Nine-Day Course of Linezolid

We report the emergence and long-lasting persistence of linezolid resistance in an ampicillin-resistant Enterococcus faecium strain in the intestine of a neutropenic oncohematologic patient receiving chemotherapy. The patient was first colonized by an epidemic ampicillin-resistant E. faecium (ARE)-ST117 clustering into lineage 78. This clone exhibited resistance to levofloxacin, erythromycin and high-level resistance to streptomycin and gentamicin. After receiving treatment with several broad spectrum antibiotics for febrile neutropenia, a 9-day course of oral linezolid was administered once the patient developed bacteraemia by the same ARE colonizing clone. Linezolid-resistant ARE was detected 17 days later in the follow-up fecal samples and persisted 41 days after suppression of linezolid therapy. Resistance to linezolid was associated with G2576T transversion in the 23S rRNA and the presence of cfr gene was not detected. The persistence of G2576T-ARE strains, especially in oncohematologic patients with injured intestinal membranes, could increase the risk of bacteraemia.

Occurrence of antimicrobial resistance and virulence genes, and distribution of enterococcal clonal complex 17 from animals and human beings in Korea

Enterococci are major zoonotic bacteria that cause opportunistic infections in human beings and animals. Moreover, pathogenic strains can be disseminated between human beings and animals, particularly companion animals that come into frequent contact with people. Recently, Enterococcus faecium clonal complex 17 (CC17) has emerged as a pandemic clone. Most CC17 strains are ampicillin resistant and possess virulence genes such as esp and hyl. Despite the possible dissemination of CC17 between human beings and animals, prevalence data about CC17 in animals is limited. In the present study, the phenotypes and genotypes of antimicrobial resistance were compared, as well as virulence gene profiles from 184 enterococci strains isolated from chickens, pigs, companion animals, and human patients in Korea. Ampicillin-resistant E. faecium (AREF) strains were selected, and multilocus sequence typing was performed to investigate the dispersion of CC17 among animals and human beings. The companion animal and human isolates showed high resistance rates to ampicillin and ciprofloxacin, whereas food animal isolates showed high tetracycline and erythromycin resistance rates. Ampicillin-resistant E. faecium was only detected in human (21/21 E. faecium, 100%) and companion animal (3/5 E. faecium, 60%) isolates, and all human AREF strains and 1 canine AREF strain were confirmed as CC17. In conclusion, the occurrence of antimicrobial resistance and virulence genes, and the distribution of enterococcal CC17 in companion animal enterococcal strains were similar to those of human strains rather than to those of food animal strains.

Dynamics of ampicillin-resistant Enterococcus faecium clones colonizing hospitalized patients: data from a prospective observational study

BackgroundLittle is known about the dynamics of colonizing Enterococcus faecium clones during hospitalization, invasive infection and after discharge.MethodsIn a prospective observational study we compared intestinal E. faecium colonization in three patient cohorts: 1) Patients from the Hematology Unit at the University Hospital Basel (UHBS), Switzerland, were investigated by weekly rectal swabs (RS) during hospitalization (group 1a, n = 33) and monthly after discharge (group 1b, n = 21). 2) Patients from the Intensive Care Unit (ICU) at the University Medical Center Utrecht, the Netherlands (group 2, n = 25) were swabbed weekly. 3) Patients with invasive E. faecium infection at UHBS were swabbed at the time of infection (group 3, n = 22). From each RS five colonies with typical E. faecium morphology were picked. Species identification was confirmed by PCR and ampicillin-resistant E. faecium (ARE) isolates were typed using Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). The Simpson's Index of Diversity (SID) was calculated.ResultsOut of 558 ARE isolates from 354 RS, MT159 was the most prevalent clone (54%, 100%, 52% and 83% of ARE in groups 1a, 1b, 2 and 3, respectively). Among hematological inpatients 13 (40%) had ARE. During hospitalization, the SID of MLVA-typed ARE decreased from 0.745 [95%CI 0.657-0.833] in week 1 to 0.513 [95%CI 0.388-0.637] in week 3. After discharge the only detected ARE was MT159 in 3 patients. In the ICU (group 2) almost all patients (84%) were colonized with ARE. The SID increased significantly from 0.373 [95%CI 0.175-0.572] at week 1 to a maximum of 0.808 [95%CI 0.768-0.849] at week 3 due to acquisition of multiple ARE clones. All 16 patients with invasive ARE were colonized with the same MLVA clone (p < 0.001).ConclusionsIn hospitalized high-risk patients MT159 is the most frequent colonizer and cause of invasive E. faecium infections. During hospitalization, ASE are quickly replaced by ARE. Diversity of ARE increases on units with possible cross-transmission such as ICUs. After hospitalization ARE are lost with the exception of MT159. In invasive infections, the invasive clone is the predominant gut colonizer.

High-density fecal Enterococcus faecium colonization in hospitalized patients is associated with the presence of the polyclonal subcluster CC17

Enterococcus faecium belonging to the polyclonal subcluster CC17, with a typical ampicillin-resistant E. faecium (AREfm) phenotype, have become prevalent among nosocomial infections around the world. High-density intestinal AREfm colonization could be one of the factors contributing to the successful spread of these pathogens. We aimed to quantify the enterococcal intestinal colonization densities in stool samples from AREfm-colonized and non-colonized patients using fluorescent in situ hybridization (FISH). Stool samples were collected from AREfm-colonized (n = 8) and non-colonized (n = 8) patients. The relative number of Enterococcus faecalis and E. faecium was determined by FISH using specific 16S rRNA probes, while the total amount of bacterial cells was counted by staining the sample with 4',6-diamidino-2-phenylindole (DAPI). The median bacterial cell numbers in fecal samples, counted by DAPI staining, were 7.7 × 10(9) and 4.8 × 10(9) cells/g for AREfm-colonized and non-colonized patients, respectively (p = 0.34). The E. faecium densities in AREfm-colonized patients, accounting for 0.5-7% of all fecal bacterial cells, exceeded E. faecalis levels by over ten-fold. E. faecium was not detected in non-colonized patients. This study demonstrated high E. faecium cell densities in stool samples from patients colonized with AREfm. Increased cell densities may contribute to host-to-host transmission and environmental contamination, facilitating the spread of AREfm in the hospital setting.

Dogs are a reservoir of ampicillin-resistant Enterococcus faecium lineages associated with human infections.

Ampicillin resistance is a marker for hospital-associated Enterococcus faecium. Feces from 208 dogs were selectively screened for the occurrence of ampicillin-resistant E. faecium (AREF). AREF was detected in 42 (23%) of 183 dogs screened in a cross-sectional study in the United Kingdom and in 19 (76%) of 25 dogs studied longitudinally in Denmark. AREF carriage was intermittent in all dogs studied longitudinally. Multilocus sequence typing of 63 canine AREF isolates revealed the presence of 13 distinct sequence types. Approximately 76% of the isolates belonged to hospital-adapted clonal complex 17 (CC17), including those of sequence types ST-78 and ST-192, which are widespread in European and Asian hospitals. Longitudinal screening of 18 healthy humans living in contact with 13 of the dogs under study resulted in the identification of a single, intermittent CC17 carrier. This person carried one of the sequence types (ST-78) recovered from his dog. Based on PCR and Southern hybridization analyses, the putative virulence gene cluster from orf903 to orf907 was widespread in canine AREF isolates (present in 97%), whereas orf2351 (present in 26% of isolates) and orf2430 (present in 31%) were strongly associated with CC17-related sequence types (P<0.05). Surprisingly, esp and hyl were not detected in any of the isolates. The antimicrobial resistance profiles of canine AREF isolates generally differed from those previously described for clinical human isolates. The results indicate that dogs are frequent carriers of CC17-related lineages and may play a role in the spread of this nosocomial pathogen. The distinctive virulence and antimicrobial resistance profiles observed among canine AREF isolates raise interesting questions about the origin and evolution of the strains causing human infections.

High acquisition and environmental contamination rates of CC17 ampicillin-resistant Enterococcus faecium in a Dutch hospital

Enterococcus faecium has rapidly emerged as a nosocomial pathogen worldwide, and the majority of these isolates belong to clonal complex-17 (CC17). In Europe, CC17 isolates are usually ampicillin-resistant, but most are still vancomycin-sensitive. We aimed to study ampicillin-resistant E. faecium (ARE) epidemiology in our hospital. In a 3 month study, 210 of 358 admissions (59%) to haematology and gastroenterology/nephrology were screened for rectal ARE colonization on admission (<48 h) and 148 of 210 (70%) also at discharge (<72 h). In a second (3 month) study, environmental swabs from eight predetermined sites were obtained from ARE-colonized haematology patients once weekly. All ARE isolates were genotyped by multiple-locus variable-number tandem repeat analysis (MLVA). ARE admission prevalence was 10% and 16% and acquisition rates were 39% and 15% in haematology and gastroenterology/nephrology, respectively. Carriage on admission was associated with previous admission <1 year (OR 5.0, 95% CI 1.8-14.0) and acquisition with beta-lactam (OR 2.7, 95% CI 1.1-6.7) and quinolone use (OR 3.1, 95% CI 1.1-8.2). Five of the 57 (9%) colonized patients developed invasive ARE infections. Genotyping revealed 12 genotypes (all CC17) with two MLVA types responsible for 94% of acquisitions. In 18 of the 19 colonized patients, the environment was contaminated with ARE. Sites most often contaminated were the toilet seat (43%), over-bed table (34%) and television remote control (28%). CC17 ARE epidemiology is characterized by high admission (10% to 16%), acquisition (15% to 39%) and environmental contamination (22%) rates, resulting from cross-transmission, readmission and antibiotic pressure. A multifaceted infection control approach will be needed to curtail further spread.

Emergence of CC17Enterococcus faecium: from commensal to hospital-adapted pathogen

For many years, Enterococcus faecium was considered to be a commensal of the digestive tract, which only sporadically caused opportunistic infections in severely ill patients. Over the last two decades, vancomycin-resistant E. faecium (VREF) has emerged worldwide as an important cause of nosocomial infections, especially in immunocompromised patients. The global Vancomycin-resistant enterococci (VRE) epidemic was preceded by the emergence of ampicillin-resistant E. faecium (AREfm) in the United States in the early 1980s, followed by the rapid emergence of VRE in the 1990s. A similar increase of VRE may occur in countries with still low levels of VRE in hospitals (such as The Netherlands), but increasing incidence of AREfm infections. Molecular epidemiological studies of both human- and animal-derived E. faecium isolates using multilocus sequence typing revealed the existence of host-specific genogroups, including a specific genetic lineage designated CC17, associated with hospital-related isolates. These strains were characterized by ampicillin and quinolone resistance. In addition, the majority of these CC17 isolates contain over hundred hospital-clade-specific genes, including mobile elements, phage genes and plasmid sequences, hypothetical and membrane proteins and antibiotic and regulatory genes and a putative pathogenicity island including the esp gene.

2002-2003 Bacterial resistance surveillance on Gram-positive cocci isolated from hospital acquired infections and community acquired infections in China

目的 监测我国不同地区医院获得性感染(HAI)与社区获得性感染(CAI)患者中革兰阳性球菌耐药状况.方法按原设计方案对14家医院31个研究病房,从2002年7月1日至2003年6月30日年度内分离的770株革兰阳性球菌,采用国际标准平皿二倍稀释法进行体外敏感试验,以MIC50、MIC90表示抗菌药物的抗菌活性,并按2002年美国实验室标准委员会(NCCLS)指导原则的标准计算细菌对抗菌药物的耐药率(R)%、中介率(I)%和敏感率(S)%.结果从住院感染患者中分离到葡萄球菌390株,甲氧西林耐药金黄色葡萄球菌(MRSA)与甲氧西林耐药表皮葡萄球菌(MRSE)的检出率分别为41.0%(68/166)与29.1%(34/117), 苯唑西林耐药金黄色葡萄球菌(ORSA)与苯唑西林耐药表皮葡萄球菌(ORSE)的检出率分别为41.6%(69/166)和82.1%(96/117).HAI患者中MRSA与ORSA检出率均为60.7%(17/28),显著高于CAI患者中MRSA与ORSA检出率,后两者分别为37.0%(51/138)与37.7%(52/138).未发现对万古霉素、去甲万古霉素耐药或中介金黄色葡萄球菌或凝固酶阴性葡萄球菌菌株.青霉素耐药肺炎链球菌(PRSP+PISP)的总耐药率为35.3%(12/34),包括耐药率R%(2.9%,1/34)和中介率I%(32.4%,11/34).从研究病房分离到肠球菌220株,非研究病房分离到95株共计315株,其中粪肠球菌251株,屎肠球菌58株,两者比值为4.3∶ 1.屎肠球菌对氨苄西林耐药率为72.4%(42/58),显著高于粪肠球菌对氨苄西林的耐药率37.5%(94/251) (P<0.01).发现5株对万古霉素中介,表型属Van B型的粪肠球菌,并检出3株Van A型对万古霉素、去甲万古霉素及替考拉宁都耐药的屎肠球菌.结论革兰阳性球菌对所测定药物的耐药状况包括MRSA、ORSA、PRSP(R+I)及AREF与中国细菌耐药监测组以往报道结果规律相似或耐药率略有增加,与文献报道收集西太区某些监测资料大体一致.本次监测发现3株Van A型屎肠球菌对检测的3种糖肽类抗生素全部耐药。

Clonality among ampicillin-resistant Enterococcus faecium isolates in Sweden and relationship with ciprofloxacin resistance

To investigate clonal relationships in a nationwide sample of human Enterococcus faecium isolates. Biochemical fingerprinting (PhP (PhenePlate) typing) was used to compare 180 fecal ampicillin-resistant E. faecium (ARE) isolates with 169 matched fecal ampicillin-susceptible E. faecium (ASE) isolates from patients in 23 hospitals, collected in 1998, and to study 39 fecal ARE isolates from non-hospitalized individuals collected in 1998, and five ARE and 29 ASE isolates from the early 1990s. Representative ARE and ASE isolates were subjected to pulsed-field gel electrophoresis (PFGE) analysis of genomic DNA and sequencing of the regions encoding the fluoroquinolone targets of the enzymes GyrA and ParC. Both PhP and PFGE results showed a higher homogeneity among ARE than among ASE isolates (P < 0.001). One PhP type (FMSE1) comprised 73% of the hospital ARE isolates (53% of ARE isolates from non-hospitalized individuals, and four of five ARE isolates from the early 1990s), but only 1% of the ASE isolates. PFGE of the hospital E. faecium isolates revealed that 23 of the 25 ARE isolates and one of the 22 ASE isolates were of one dominating type. High-level resistance to ciprofloxacin (MIC > 16 mg/L) was present in 91% of ARE isolates, whereas only low-level resistance (MIC 4-16 mg/L; 35% of isolates) was found among ASE isolates. One mutation in parC (codon 80) and one of two mutations in gyrA (codons 83 or 87) were detected in all ARE isolates tested with high-level ciprofloxacin resistance, but were lacking in ARE and ASE isolates with low-level ciprofloxacin resistance. Most ARE isolates in Sweden were clonally related. High-level ciprofloxacin resistance was found in ARE isolates of PhP type FMSE1 as well as in other PhP types, but never in ASE isolates.