An epidemiological and molecular study regarding the spread of vancomycin-resistant Enterococcus faecium in a teaching hospital in Bogotá, Colombia 2016.

BACKGROUND: Enterococcus faecium is ranked worldwide as one of the top ten pathogens identified in healthcare-associated infections (HAI) and is classified as one of the high priority pathogens for research and development of new antibiotics worldwide. Due to molecular biology techniques' higher costs, the approach for identifying and controlling infectious diseases in developing countries has been based on clinical and epidemiological perspectives. Nevertheless, after an abrupt vancomycin-resistant Enterococcus faecium dissemination in the Méderi teaching hospital, ending up in an outbreak, further measures needed to be taken into consideration. The present study describes the vancomycin-resistant Enterococcus faecium pattern within Colombian's largest installed-bed capacity hospital in 2016. METHODS: Thirty-three vancomycin-resistant Enterococcus faecium isolates were recovered during a 5-month period in 2016. Multilocus variable-number tandem-repeat analysis was used for molecular typing to determine clonality amongst strains. A modified time-place-sequence algorithm was used to trace VREfm spread patterns during the outbreak period and estimate transmission routes. RESULTS: Four clonal profiles were identified. Chronological clonal profile follow-up suggested a transitional spread from profile "A" to profile "B", returning to a higher prevalence of "A" by the end of the study. Antibiotic susceptibility indicated high-level vancomycin-resistance in most isolates frequently matching vanA gene identification. DISCUSSION: Transmission analysis suggested cross-contamination via healthcare workers. Despite epidemiological control of the outbreak, post-outbreak isolates were still being identified as having outbreak-related clonal profile (A), indicating reduction but not eradication of this clonality. This study supports the use of combined molecular and epidemiological strategies in an approach to controlling infectious diseases. It contributes towards a more accurate evaluation of the effectiveness of the epidemiological measures taken regarding outbreak control and estimates the main cause related to the spread of this microorganism.

Co-transmission of Rahnella aquatilis between hospitalized patients.

Rahnella aquatilis is an environmental Gram-negative bacillus that is rarely reported as human pathogen, being mainly associated with infections in immunocompromised patients. Herein we describe two cases of R. aquatilis isolates recovered from endotracheal aspirate cultures of different patients in a tertiary hospital located in the city of São Paulo, Brazil. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S rDNA gene sequencing were performed to confirm bacterial identification after the isolates being erroneously identified as Pantoea spp. by automated system. Both isolates showed the same PFGE pattern and presented the ß-lactamase encoding gene blaRAHN-1, responsible for resistance to cephalothin. The isolates were susceptible to broad-spectrum cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and polymyxin B. This report shows the presence and transmission of uncommon bacteria in the nosocomial environment and alerts us about the need for new tools of correct microbiologic diagnosis.

Comparison of Enterococcus faecium and Enterococcus faecalis Strains isolated from water and clinical samples: antimicrobial susceptibility and genetic relationships.

Enterococci are part of the normal intestinal flora in a large number of mammals, and these microbes are currently used as indicators of fecal contamination in water and food for human consumption. These organisms are considered one of the primary causes of nosocomial and environmental infections due to their ability to survive in the environment and to their intrinsic resistance to antimicrobials. The aims of this study were to determine the biochemical patterns and antimicrobial susceptibilities of Enterococcus faecalis and E. faecium isolates from clinical samples and from water (groundwater, water from the Xochimilco wetland, and treated water from the Mexico City Metropolitan Area) and to determine the genetic relationships among these isolates. A total of 121 enterococcus strains were studied; 31 and 90 strains were isolated from clinical samples and water (groundwater, water from the Xochimilco wetland, and water for agricultural irrigation), respectively. Identification to the species level was performed using a multiplex PCR assay, and antimicrobial profiles were obtained using a commercial kit. Twenty-eight strains were analyzed by pulsed-field gel electrophoresis (PFGE). E. faecium strains isolated from water showed an atypical biochemical pattern. The clinical isolates showed higher resistance to antibiotics than those from water. Both the enterococci isolated from humans, and those isolated from water showed high genetic diversity according to the PFGE analysis, although some strains seemed to be closely related. In conclusion, enterococci isolated from humans and water are genetically different. However, water represents a potential route of transmission to the community and a source of antimicrobial resistance genes that may be readily transmitted to other, different bacterial species.

[Analysis of nosocomial pediatric bacteremias at a general hospital between 1990 and 2006. The impact of attending the intravascular therapy]. / Análisis de las bacteriemias nosocomiales pediátricas en un hospital general entre 1990 y 2006. Impacto de la atención a la terapia intravascular.

INTRODUCTION: The administration of parenteral infusates is a frequent intervention that is considered innocuous; moreover, the risk of this procedure which offers a direct access to the bloodstream is minimized. OBJECTIVE: To evaluate the epidemiology of nosocomial pediatric bacteremias after implementing a control program. METHODS: Analysis of pediatric bacteremias was made in 3 periods: 1) 1990-1992, prior to establishing strategies to avoid contamination of parenteral infusions; 2) 1996, the phase after establishing these strategies; and 3) 2005-2006, the recent situation in the hospital. RESULTS: The proportion of gram-negative rods isolated in blood cultures dropped from 82.9 to 35.1% (p = 0.004) during the 17-year study period. There was no significant difference in the proportion of gram-negative rods isolated from intravascular catheters. The proportion of contaminated parenteral infusions dropped from 22.2% to 0.4% (p < 0.001). DISCUSSION: The strategies established to avoid the contamination of parenteral infusions were associated with a reduction in the proportion of gram-negative rods in blood cultures, although the proportion is still higher than that in developed countries, probably related to catheter contamination. We suggest establishing similar strategies in other hospitals from developing countries.

Outbreak of vancomycin-resistant enterococci in a tertiary hospital: the lack of effect of measures directed mainly by surveillance cultures and differences in response between Enterococcus faecium and Enterococcus faecalis.

To describe the effect of active surveillance to control vancomycin-resistant enterococci (VRE) after an outbreak, 549 surveillance rectal cultures were performed in 308 patients (35% positive). An educational intervention to prevent transmission was implemented. Infection and colonization by VR- Enterococcus faecalis decreased, but Enterococcus faecium persisted despite control measures. Infections by VR-E faecalis fell to zero in 2008. We observed difficulties in controlling colonization with measures directed mainly by surveillance cultures and differences between responses of E faecium and E faecalis.

[Environmental contamination during a vancomycin-resistant Enterococci outbreak at a hospital in Argentina]. / Contaminación ambiental durante un brote de enterococo resistente a vancomicina en un hospital de Argentina.

INTRODUCTION: Vancomycin-resistant enterococci isolates (VRE) have caused numerous outbreaks in intensive care units (ICUs). A contaminated hospital environment, the hands of health care workers (HCW), and carrier patients may play important roles in perpetuating the chain of transmission in these outbreaks. The aims of this study were to report the first VRE outbreak in our center and assess the role of environmental contamination and HCW hands in the spread of new cases of enterococcal infection. MATERIAL AND METHOD: Between August and December 2003, surveillance cultures were performed with samples from all patients (n = 113) admitted to the ICU, as well as cultures of samples from the environment (n = 69) and HCW hands (n = 23). RESULTS: Eighteen clinical samples from 8 patients and 7 environmental samples yielded Enterococcus faecium (24 strains) and E. avium (1 strain). VRE was not detected on HCW hands. All the VRE isolates belonged to a single clone and carried the vanA gene. CONCLUSION: Environmental contamination provides an important reservoir for future outbreaks of VRE, perpetuating transmission of the microorganism in the hospital setting.

Global spread of vancomycin-resistant Enterococcus faecium from distinct nosocomial genetic complex.

Vancomycin-resistant enterococci (VRE) have caused hospital outbreaks worldwide, and the vancomycin-resistance gene (vanA) has crossed genus boundaries to methicillin-resistant Staphylococcus aureus. 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, population structure, and geographic distribution of 411 VRE and vancomycin-susceptible Enterococcus faecium 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 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 is critical, and efforts should focus on the early disclosure of ampicillin-resistant complex-17 strains.

Clonal dissemination of VanA-type glycopeptide-resistant Enterococcus faecalis between hospitals of two cities located 100 km apart.

Nosocomial dissemination of glycopeptide-resistant enterococci represents a major problem in hospitals worldwide. In Brazil, the dissemination among hospitals in the city of São Paulo of polyclonal DNA profiles was previously described for vancomycin-resistant Enterococcus faecium. We describe here the dissemination of VanA phenotype E. faecalis between two hospitals located in different cities in the State of São Paulo. The index outbreak occurred in a tertiary care university hospital (HCUSP) in the city of São Paulo and three years later a cluster caused by the same strain was recognized in two patients hospitalized in a private tertiary care hospital (CMC) located 100 km away in the interior of the state. From May to July 1999, 10 strains of vancomycin-resistant E. faecalis were isolated from 10 patients hospitalized in the HCUSP. The DNA genotyping using pulsed-field gel electrophoresis (PFGE) showed that all isolates were originated from the same clone, suggesting nosocomial dissemination. From May to July 2002, three strains of vancomycin-resistant E. faecalis were isolated from two patients hospitalized in CMC and both patients were colonized by the vancomycin-resistant Enterococcus in skin lesions. All isolates from CMC and HCUSP were highly resistant to vancomycin and teicoplanin. The three strains from CMC had minimum inhibitory concentration >256 micro g/ml for vancomycin, and 64 (CMC 1 and CMC 2) and 96 micro g/ml (CMC 3) for teicoplanin, characterizing a profile of VanA resistance to glycopeptides. All strains had the presence of the transposon Tn1546 detected by PCR and were closely related when typed by PFGE. The dissemination of the E. faecalis VanA phenotype among hospitals located in different cities is of great concern because E. faecalis commonly colonizes the gastrointestinal tract of patients and healthy persons for periods varying from weeks to years, which, together with the persistence of vancomycin-resistant Enterococcus in hospital rooms after standard cleaning procedures, increases the risk of the dissemination and reservoir of the bacteria.

Leuconostoc pseudomesenteroides as a cause of nosocomial urinary tract infections.

The phenotypic and genotypic characterization of five clinical isolates of Leuconostoc pseudomesenteroides associated with nosocomially acquired urinary tract infections is described. All the strains were susceptible to chloramphenicol, clindamycin, erythromycin, gentamicin, and tetracycline; all were resistant to nalidixic acid, norfloxacin, and vancomycin; and all were intermediately affected by ampicillin and penicillin. Analysis of chromosomal DNA by pulsed-field gel electrophoresis after treatment with SmaI indicated a clonal relationship of the isolates. The results provide evidence for the possibility of nosocomial transmission of this unusual opportunistic, vancomycin-resistant pathogen.

Vancomycin-resistant enterococci in intensive care hospital settings.

Vancomycin-resistant enterococci (VRE) have recently emerged as a nosocomial pathogen and present an increasing threat to the treatment of severely ill patients in intensive-care hospital settings. We outline results of a study of the epidemiology of VRE transmission in ICUs and define a reproductive number R0; the number of secondary colonization cases induced by a single VRE-colonized patient in a VRE-free ICU, for VRE transmission. For VRE to become endemic requires R0 > 1. We estimate that in the absence of infection control measures R0 lies in the range 3-4 in defined ICU settings. Once infection control measures are included R0 = 0.6, suggesting that admission of VRE-colonized patients can stabilize endemic VRE.