Global scenario of the RmtE pan-aminoglycoside-resistance mechanism: emergence of the rmtE4 gene in South America associated with a hospital-related IncL plasmid.

Antimicrobial resistance (AMR) mechanisms, especially those conferring resistance to critically important antibiotics, are a great concern for public health. 16S rRNA methyltransferases (16S-RMTases) abolish the effectiveness of most clinically used aminoglycosides, but some of them are considered sporadic, such as RmtE. The main goals of this work were the genomic analysis of bacteria producing 16S-RMTases from a 'One Health' perspective in Venezuela, and the study of the epidemiological and evolutionary scenario of RmtE variants and their related mobile genetic elements (MGEs) worldwide. A total of 21 samples were collected in 2014 from different animal and environmental sources in the Cumaná region (Venezuela). Highly aminoglycoside-resistant Enterobacteriaceae isolates were selected, identified and screened for 16S-RMTase genes. Illumina and Nanopore whole-genome sequencing data were combined to obtain hybrid assemblies and analyse their sequence type, resistome, plasmidome and pan-genome. Genomic collections of rmtE variants and their associated MGEs were generated to perform epidemiological and phylogenetic analyses. A single 16S-RMTase, the novel RmtE4, was identified in five Klebsiella isolates from wastewater samples of Cumaná. This variant possessed three amino acid modifications with respect to RmtE1-3 (Asn152Asp, Val216Ile and Lys267Ile), representing the most genetic distant among all known and novel variants described in this work, and the second most prevalent. rmtE variants were globally spread, and their geographical distribution was determined by the associated MGEs and the carrying bacterial species. Thus, rmtE4 was found to be confined to Klebsiella isolates from South America, where it was closely related to ISVsa3 and an uncommon IncL plasmid related with hospital environments. This work uncovered the global scenario of RmtE and the existence of RmtE4, which could potentially emerge from South America. Surveillance and control measures should be developed based on these findings in order to prevent the dissemination of this AMR mechanism and preserve public health worldwide.

Fluoroquinolonas en aves, huevos, alimentos avícolas y su impacto en la microbiota intestinal de aves / Fluoroquinolone in birds, eggs, poultry feeds and their impact on the intestinal microbiota

Se detectó la presencia de fluoroquinolonas en varios alimentos (huevos, alimentos para aves y pechuga de pollo), así como determinar el perfil de susceptibilidad de ácido nalidíxico y ciprofloxacina de las enterobacterias aisladas del contenido intestinal de pollos de Cumaná. Se estudiaron alimentos iniciadores y de engorde (de cinco marcas comerciales) y uno para gallinas ponedoras, así como pechugas de pollos nacionales y de Brasil. I-2 y E-1 fueron los que tuvieron las concentraciones más altas de enrofloxacina. El alimento para las gallinas ponedoras (AP 2,35 µg/mg) tuvo más enrofloxacina que los de los pollos. En los huevos, la mayor acumulación se vio en las yemas. Los pollos nacionales (0,43-0,56 µg/mg) acumularon más ciprofloxacina que los pollos de Brasil (0,14 µg/mg). De los hisopados rectales de los pollos, E. coli fue la principal especie aislada. Por antibiograma, 48% de las cepas fueron resistentes a las quinolonas probadas (ácido nalidíxico y ciprofloxacina). Cuando se determinó la concentración mínima inhibitoria a ciprofloxacina, todas las cepas fueron resistentes (8-128 µg/ml). Todos los alimentos muestreados exceden los límites máximos de fluoroquinolonas permitidos en humanos, lo cual ejerce una presión selectiva importante en las bacterias de la microbiota intestinal de los pollos

To detect the presence of fluoroquinolones in several foods (eggs, poultry food and chicken breast), as well as to determine the susceptibility profile of nalidixic acid and ciprofloxacin of strains of enterobacterias from chicken's intestinal content from Cumaná. Starter and fattening foods (of five commercial marks), and one for laying hens, were studied, as well as domestic chicken's breast (and Brazil. I-2 and E-1 were the ones with the highest concentrations of enrofloxacin. The food for laying hens (AP 2,35 µg/mg) had more enrofloxacin than those for chickens. In eggs, greatest accumulation was seen in the yolks. Domestic chickens (0,43-0,56 µg/mg) accumulated more ciprofloxacin than Brazilian ones (0,14 µg/mg). E. coli was the main specie from chicken rectal swabs. By antimicrobial susceptibility testing, 48% were resistant to both quinolones (nalidixic acid and ciprofloxacin). When the minimum inhibitory concentration of ciprofloxacin was determined, all strains were resistant (8-128 µg/ml). All sampled foods exceeded the maximum limits of fluoroquinolones allowed in humans, which puts significant selective pressure on the bacteria in the chicken gut microbiota

Estudio de la Inhibición de formación de biopelículas en cepas de Pseudomonas aeruginosa en presencia de própolis / Inhibition study of biofilms production of Pseudomonas aeruginosa strains in the presence of propolis

Uno de los principales fracasos de los tratamientos antibióticos de las infecciones por P. aeruginosa, es debido a la producción de biopelículas. El objetivo de este trabajo fue estudiar la inhibición de formación de biopelículas en cepas de Pseudomonas aeruginosa en presencia de própolis. A todas las cepas se les determinó el perfil de susceptibilidad y se hicieron pruebas de sinergismo. Se detectó el nivel de producción de biopelículas sobre membranas de nitrocelulosa y por microscopía electrónica de transmisión. Se estudió la inhibición de las biopelículas por própolis por dilución en placas. En el hospital de Cumaná, "Dr. Julio Rodríguez", se aislaron cepas de P. aeruginosa, de diferentes procesos infecciosos, principalmente, pie diabético. Todas las cepas produjeron biopelículas a diferentes niveles (leve 60%, moderado 24% e intenso 16%). Sesenta por ciento de las cepas son productoras de MBL y 49% de AmpC. El antibiotipo predominante fue la resistencia a aminoglucósidos y fluoroquinolonas (XII). Siete cepas fueron resistentes a colistin. Las biopelículas tratadas con própolis (10 µg/ml), fueron inhibidas con éxito en su casi totalidad. En conclusión, el própolis logró erradicar la formación de biopelículas in vitro, rompiendo las barreras de los diferentes mecanismos de resistencia a los antibióticos expresados por las cepas de P. aeruginosa estudiadas en este trabajo

One of the main failures of antibiotics treatments of P. aeruginosa infections is due to the production of biofilms. The objective of this work was to study the inhibition of biofilm production in Pseudomonas aeruginosa strains in the presence of propolis. Susceptibility testing and synergism were performed in all strains. Biofilm production level was determined onto nitrocellulose membranes and transmission electronic microscopy. Biofilm inhibition propolis was did on plate dilution. "Dr. Julio Rodríguez" hospital, in Cumaná, P. aeruginosa strains were isolated from different infectious processes, mainly diabetic foot. All the strains produced biofilm at different levels (60% mild, 24% moderate and 16% high). Sixty percent of the strains are producers of MBL, and 49% of AmpC. The predominant antibiotype was resistance to aminoglycosides and fluoroquinolones (XII). Seven strains were resistant's to colistin. Biofilms treated with propolis (10 µg/ml) were almost completely inhibited. In conclusion, the propolis achieved to eradicate the in vitro biofilm production, breaking the barriers of the different mechanisms of resistance to the antibiotics expressed by the P. aeruginosa strains studied in this work

Neumonía necrotizante y empiema pleural por Salmonella no Typhi en paciente inmunocompetente

Los distintos serotipos de Salmonella han sido involucrados generalmente en infecciones gastrointestinales. Las complicaciones pulmonares tanto la neumonía como el empiema son consideradas muy raras y generalmente se presentan en hospederos con alteraciones del sistema inmunológico o con enfermedades predisponentes. Se reporta el caso de una niña de 7 años de edad sin enfermedad previa y sin síntomas gastrointestinales, quien presentó fiebre, tos productiva y dificultad respiratoria progresiva. La radiografía mostró una zona de opacidad de compromiso pulmonar total derecho con desplazamiento del cardiomediastino hacia la izquierda. Se realizó toracentesis con colocación inmediata de sonda de drenaje torácico; del líquido pleural se aisló Salmonella no Typhi. Recibió tratamiento endovenoso con ceftazidima y ciprofloxacina por 12 días, seguido de 12 días más de trimetoprim/sulfametoxazol de forma ambulatoria. Este es el primer reporte para el país, del asilamiento de Salmonella no Typhi relacionado con enfermedad respiratoria severa en una paciente inmunológicamente competente.

The different serotypes of Salmonella have been generally involved in gastrointestinal infections, pulmonary complications both pneumonia and empyema are considered very rare and usually occur in hosts with alterations of the immune system or with predisposing diseases. We report the case of a 7-year-old girl without previous illness and without gastrointestinal symptoms, who presented fever, productive cough and progressive respiratory difficulty. The radiograph showed a zone of opacity of right total pulmonary involvement with displacement of the cardiomediastinum to the left. Thoracentesis was performed with immediate thoracic drainage tube replacement; of the pleural fluid was isolated Salmonella no Typhi. She received intravenous treatment with ceftazidime and ciprofloxacin for 1 days, followed by 12 days of trimethoprim/sulfamethoxazole on an outpatient basis. This is the first report for the country, of the isolation of Salmonella non Typhi related to severe respiratory disease in an immunologically competent patient.

Presencia de Enterocccus VanB a nivel intestinal en pacientes de la Unidad de hemodiálisis y cuidados intensivos del Hospital "Luís Ortega", en Porlamar, Estado Nueva Esparta

Introducción: Pacientes hospitalizados, portadores de enterococos resistentes a los glicopéptidos, son una bomba de tiempo, ya que largas estadías y terapias antibióticas prolongadas, permiten la translocación de esas cepas y la aparición de endocarditis o infecciones del tracto urinario. Metodología: En un estudio realizado en las Unidades de hemodiálisis y Terapia Intensiva en el Hospital "Luís Ortega" de Porlamar en el primer semestre del año 2008, se muestrearon 54 pacientes. Resultados: El estudio molecular mostró la presencia de la especie E. faecalis (475 pb), sensible a linezolid, gentamicina, estreptomicina y teicoplanina. El genotipo de resistencia encontrado en las cepas fue vanB (647 pb). La prevalencia de cepas VanB fue de 4 % en el servicio de HD. Ninguno de los pacientes de Terapia Intensiva estaba colonizado por cepas con alto nivel de resistencia a glicopéptidos. Conclusiones: Los estudios de vigilancia epidemiológica son fundamentales para la detección de bacterias multirresistentes en pacientes hospitalizados y evitar su diseminación en los servicios.

Introduction: Hospitalized patients with resistant to glycopeptides enterococci, are a time bomb, since long stays and prolonged antibiotic therapies allow the translocation of these strains and the occurrence of endocarditis or infections of the urinary tract. Methodology: In a study carried out on Hemodialysis and Intensive care wards on "Luís Ortega" Hospital, from Porlamar, during the first semester of 2008, 54 patients were sampled. Results: Molecular study shown E. faecalis specie (475 pb), susceptible to linezolid, gentamycin, streptomycin, and teicoplanin. Resistance genotype found was vanB (647 pb). Prevalence of VanB strains on HD ward was 4 %. No one patient of Intensive Care Unit had high level glycopeptides-resistant strains. Conclusions: Epidemiological surveillance studies are essential for the detection of multiresistant bacteria in hospitalized patients and avoid their dissemination in services.

Determinación de cepas de Enterococcus resistentes a antibióticos glicopéptidos en pacientes hospitalizados en el Hospital "Santos Aníbal Dominicci", Carúpano, Estado Sucre

Introducción: El impacto clínico de infecciones causadas por cepas de enterococos resistentes a glicopéptidos, es encontrar la terapia adecuada para salvar la vida de ese paciente, además de la transferencia horizontal de determinantes de resistencia. Es un reto determinar el origen de la cepa productora del cuadro infeccioso (endógeno o exógeno). Metodología: Se estudiaron 111 hisopados rectales y muestras de heces de pacientes en hemodiálisis y Unidad de Cuidados Intensivos del Hospital "Santos Aníbal Dominicci" (HSAD) de Carúpano, Venezuela, durante el período de febrero­julio 2007, con el objeto de determinar pacientes portadores de cepas de Enterococcus resistentes a los glicopéptidos. El aislamiento de Enterococcus se realizó en agar bilis esculina azida con y sin vancomicina (6 mg/ mL); a las cepas crecidas en cribado se les determinó la concentración mínima inhibitoria (CMI). La detección de la ligasa de resistencia se hizo por PCR múltiple. Resultados: La CMI de vancomicina estaba entre 8 y 16 mg/L, para 5 y 19 cepas respectivamente. Las cepas son intrínsecamente resistentes, tienen el genotipo vanC en 24 aislamientos: 15 vanC1 (815-bp) y 9 vanC2 (827- bp). Conclusiones: Es necesario mantener un sistema de vigilancia mediante cultivos para identificar pacientes colonizados con cepas con alto nivel de resistencia a vancomicina.

Introduction: The clinical impact of infections caused by strains of enterococci resistant to glycopeptides is to find the appropriate therapy to save the life of the patient, in addition to the horizontal transfer of resistance determinants. It is a challenge to determine the origin of the infectious (endogenous or exogenous) disease producing strain. Methodology: One hundred and ten rectal swabs and stool samples from patients in the hemodialysis unit and Intensive Care Unit of hospital "Santos Anibal Dominicci" (HSAD) in Carupano, Sucre state, Venezuela, were studied during February-July 2007 in order to determine which patients carried glycopeptideresistant Enterococcus strains. Isolation of Enterococcus was made via Bile Esculin Azide Agar with and without vancomycin (6 µg/mL). To the strains grown in screening were determined the Minimum Inhibitory Concentration (MIC). Detection of resistant ligases was done by multiplex PCR. Results: Minimun Inhibitory Concentration (MIC) levels were 8 mg/L and 16 mg/L for 5, and 19 strains, respectively. The strains are inherently resistant, have the vanC genotype in 24 isolates: 15 vanC1 (815-bp), and 9 vanC2 (827-bp). Conclusions: It could be helpful to create a surveillance system with a vancomycin screening to detect colonized patients with high level of glycopeptides resistant strains.

Vaginosis citolítica: presentación de un caso clínico / Cytolytic vaginosis: presentation of a clinical case

La vaginosis citolítica, descrita hace 30 años como citólisis de Döderlein, es frecuente en mujeres en la edad reproductiva y, por las características de flujo vaginal blanquecino y síntomas clínicos, es indistinguible de la vulvovaginitis micótica. Se presenta el caso de una paciente, con diagnóstico clínico presuntivo de vulvovaginitis por Candida spp. a repetición, tratada empíricamente con antifúngicos por año y medio sin ninguna mejoría. Luego de estudios microbiológicos, la coloración de Gram, demostró la presencia de 50 bacilos grampositivos por campo y abundantes núcleos celulares desnudos. El cultivo resultó puro para Lactobacillus spp., lo que permitió confirmar el diagnóstico de vaginosis citolítica. La paciente fue tratada con ampicilina-sulbactam y no ha vuelto a presentar recidivas. En conclusión, es fundamental determinar el pH vaginal de las pacientes en la consulta, así como practicar una coloración de Gram de la secreción vaginal para poner en evidencia los cambios celulares por el exceso de ácido en la vagina y así evitar tratamientos antifúngicos innecesarios que acrecentarán los trastornos de la microbiota vaginal.

Cytolytic vaginosis, described 30 years ago as Döderlein cytolysis, is common in women of reproductive age and, due to the characteristics of whitish vaginal discharge and clinical symptoms, is indistinguishable from mycotic vulvovaginitis. We describe the case of a patient with presumptive clinical diagnosis of recurrent vulvovaginitis by Candida spp. treated empirically with antifungal agents for one and a half years without improvement. After microbiological studies, Gram staining demonstrated the presence of 50 Gram-positive bacilli per field and abundant nude cell nuclei. The culture recovered pure Lactobacillus spp. which permitted the diagnosis of cytolytic vaginosis. The patient was treated with ampicillin-sulbactam and since, has not had recurrences. In conclusion, it is essential to examine the pH of the patient vaginal discharge, as well as to practice a Gram staining of the vaginal secretion to demonstrate the cellular changes produced by the excess of acid in the vagina and therefore avoid unnecessary antifungal treatments that will produce undue changes of the vaginal microbiota.

Coexistence of mcr-1 and blaNDM-1 in Escherichia coli from Venezuela.

We studied the presence of the mobile colistin resistance gene mcr-1 in human, animal, and environmental Enterobacteriaceae samples from Cumana, Venezuela, that were collected in 2015. The mcr-1 gene was detected in 2/93 Escherichia coli isolates from swine (novel ST452) and human (ST19) samples that were resistant to colistin. Whole-genome sequencing and transformation experiments identified mcr-1 on an IncI2 plasmid. One of the isolates also bore the widely spread carbapenemase NDM-1. A One Health approach is necessary to further elucidate the flux of these high-risk genes.

Tipificación de la meticilino resistencia en cepas de Staphylococcus spp. Hospital Universitario “Antonio Patricio de Alcalá”, Cumaná, estado Sucre, Venezuela / Typification of methicillin-resistance in Staphylococcus spp. strains isolated from University Hospital “Antonio Patricio de Alcalᔠin Cumana, Sucre State, Venezuela

Staphylococcus spp. figura entre las bacterias patógenas más importantes para el ser humano. La caracterización molecular de cepas de Staphylococcus meticilino resistentes (SMR) es necesaria para conocer qué tipo de complejo cromosómico estafilocócico que transporta el complejo mec (SCCmec) circula en una región. Se estudiaron 21 cepas de S. aureus y 29 de Staphylococcus coagulasa negativa (SCN) aisladas en el Laboratorio de Bacteriología del HUAPA (enero a julio 2007) resistentes a meticilina. Se les realizó antibiograma, PCR múltiple y concentración mínima inhibitoria (CMI) a las cepas positivas para mecA. 19 cepas de S. aureus y 24 de SCN fueron resistentes a oxacilina, correlacionándose con la presencia del gen mecA principalmente en S. aureus; algunas discordancias fueron observadas en SCN. Solo se identificaron Staphylococcus SCCmec tipo I y IV. La caracterización del SCCmec permitió conocer el tipo de Staphylococcus circulante en el hospital, lo que hará posible monitorear cambios futuros en estas cepas.

Staphylococcus spp. figures as one of the most important bacteria for human beings. The molecular characterization of methicillin-resistant Sttaphylococcus strains (MRS) is necessary for knowing what type of staphylococcal chromosomic complex transporting the mec complex (SCCmec) circulates in a certain area. Twenty one methicillin-resistant S. aureus and 29 coagulase negative (CNS) Staphylococcus strains isolated at the Bacteriology Laboratory of the HUAPA were studied during the January-July 2007 period. The study included antibiogram, multiple PCR, and minimum inhibitory concentration (MIC) determination of the mecA positive strains; 19 S. aureus and 24 CNS strains were oxacilline resistant, correlated with the presence of the mec.A gene, mainly in S. aureus since some discordances were observed with the CNS strains. Only Staphylococcus SCCmec type I and II were identified. The SCCmec characterization identified the Staphylococcus type circulating in the hospital, possibilitating the monitoring of future changes of these strains.

Perfil de susceptibilidad de cepas de Enterococcus spp. aisladas en animales destinados al consumo humano, criados en los estados Monagas y Anzoátegui / Susceptibility profile of Enterococcus spp. strains isolated from animals destined for human consumption, raised at Monagas and Anzoátegui States

Enterococcus spp. es un género intrínsecamente resistente a varias familias de antimicrobianos de uso clínico humano. En vista de su difícil tratamiento cuando causa infecciones graves y su fácil diseminación a través de la cadena alimentaria, se determinó el perfil de susceptibilidad de cepas de Enterococcus spp. aisladas en animales destinados al consumo humano, criados en los estados Anzoátegui y Monagas. Las muestras fueron recolectadas de forma no probabilística, intencional durante el año 2009. El perfil de susceptibilidad fue realizado por la prueba de difusión en disco para glicopéptidos, aminoglucósidos de alta carga, eritromicina, cloranfenicol, ciprofloxacina, rifampicina y ampicilina. Por ser vancomicina uno de los antimicrobianos de mayor uso en medicina humana, se hizo la búsqueda de alto nivel de resistencia a glicopéptidos en todas las cepas. La mayoría de los aislados fueron enterococos móviles (vanC). Los antimicrobianos con mayor resistencia fueron aminoglucósidos y macrólidos. La detección de cepas bacterianas resistentes a antimicrobianos de uso clínico humano, en los animales de consumo humano, pudiera traducirse en una transmisión alimenticia de este tipo de cepas en el ambiente extrahospitalario, llegando a causar, bajo circunstancias apropiadas, infecciones graves en el hombre ya que son patógenos oportunistas.

Enterococcus spp. is a genus intrinsically resistant to several antimicrobial families clinically used in humans. Due to their difficult treatment when they produce serious infections and their easy dissemination through the food chain, the susceptibility profile of Enterococcus spp. strains isolated from animals destined for human consumption raised at Monagas and Anzoátegui States was determined. Samples were collected in a intentionally non-probabilistic form during the year 2009. The susceptibility profile was done using the disk diffusion test for glycopeptides, high charge aminoglycosides, erythromycin, chloramphenicol, cyprofloxacin, rifampicin and ampicillin. Since vancomycin is one the antimicrobials most used in human medicine, the high resistance level to glycopeptides was determined for all strains. Most of the isolates were mobile enterococci (vanC). The most resistant antimicrobials were aminoglycosides and macrolids. The detection of bacterial strains resistant to antimicrobials clinically used in humans in animals destined for human consumption could be translated into an a food transmission of these type of strains in extra-hospital environments, leading to originate, under appropriate circumstances, serious infections in man, since they are opportunistic pathogens.

Transcriptional analysis of the vanC cluster from Enterococcus gallinarum strains with constitutive and inducible vancomycin resistance.

The vanC glycopeptide resistance gene cluster encodes enzymes required for synthesis of peptidoglycan precursors ending in D-Ala-D-Ser. Enterococcus gallinarum BM4174 and SC1 are constitutively and inducibly resistant to vancomycin, respectively. Analysis of peptidoglycan precursors in both strains indicated that UDP-MurNAc-tetrapeptide and UDP-MurNAc-pentapeptide[D-Ser] were synthesized in E. gallinarum SC1 only in the presence of vancomycin (4 microg/ml), whereas the "resistance" precursors accumulated in the cytoplasm of BM4174 cells under both inducing and noninducing conditions. Northern hybridization and reverse transcription-PCR experiments revealed that all the genes from the cluster, vanC-1, vanXY(C), vanT, vanR(C), and vanS(C), were transcribed from a single promoter. In the inducible SC1 isolate, transcriptional regulation appeared to be responsible for inducible expression of resistance. Promoter mapping in E. gallinarum BM4174 revealed that the transcriptional start site was located 30 nucleotides upstream from vanC-1 and that the -10 promoter consensus sequence had high identity with that of the vanA cluster. Comparison of the deduced sequence of the vanS(C) genes from isolates with constitutive and inducible resistance revealed several amino acid substitutions located in the X box (R200L) and in the region between the F and G2 boxes (D312N, D312A, and G320S) of the putative sensor kinase proteins from isolates with constitutive resistance.

VanE-type vancomycin-resistant Enterococcus faecalis clinical isolates from Australia.

Three distinct Enterococcus faecalis VanE-type isolates-BM4574, BM4575, and BM4576-obtained in Australia were studied. Expression of the resistance genes was constitutive in BM4575, probably due to a 2-bp deletion into the vanSE gene, and inducible in BM4574 and BM4576. Transcription analysis of the vanE operons suggested that the five genes were cotranscribed from an initiation site located 25 bp upstream from the ATG start codon of vanE.

vanE gene cluster of vancomycin-resistant Enterococcus faecalis BM4405.

Acquired VanE-type resistance to low levels of vancomycin (MIC = 16 microg/ml) in Enterococcus faecalis BM4405 is due to the inducible synthesis of peptidoglyean precursors terminating in D-alanine-D-serine (Fines,M., B. Prichon, P. Reynolds, D. Sahm, and P. Courvalin, Antimicrob. Agents Chemother. 43:2161-2164, 1999). A chromosomal location was assigned to the vanE operon by pulsed-field gel electrophoresis and hybridization, and its sequence was determined. Three genes, encoding the VanE ligase, the VanXYE DD-peptidase, and the VanTE serine racemase, that displayed 43 to 53% identity with the corresponding genes in the vanC operon were found. In addition, two genes coding for a two-component regulatory system, VanRE-VanSE, exhibiting 60 and 44% identity with VanR,-VanS, were present downstream from vanTE. However, because of a stop codon at position 78, VanSE was probably not functional. The five genes, with the same orientation, were shown to be cotranscribed by Northern analysis and reverse transcription-PCR. The vanE, vanXYE, and vanTE genes conferred inducible low-level resistance to vancomycin after cloning in E. faecalis JH2-2, probably following cross talk with a two-component regulatory system of the host.