Nosocomial Enterococcal Infections Research Articles

Combinatory Effect of Nitroxoline and Gentamicin in the Control of Uropathogenic Enterococci Infections.

Enterococcus faecalis, responsible for a majority of human and nosocomial enterococcal infections, is intrinsically resistant to aminoglycoside antibiotics (such as gentamicin, GEN), which must be used in a combined therapy to be effective. Nitroxoline (NTX) is an old antibiotic, underused for decades, but rediscovered now in an era of growing antibiotic resistance. In this in vitro study, the types of interactions between NTX and GEN on 29 E. faecalis strains were analyzed with an aim to find synergistic antimicrobial and antiadhesion combinations. Transmission electron microscopy (TEM) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used to analyze changes in cell morphology and bacterial proteome after monotreatments and combined treatments. The results showed the synergistic effect for six combinations on eight strains, including the ATCC29212, and an additive effect for most strains. Combinations causing a complete inhibition of adhesion were established. Cell membrane integrity was affected by NTX, while combined NTX/GEN treatment caused dramatic changes in cell morphology. Upregulation of the expression of many proteins was established, with some emerging only after combined treatment. The results strongly imply that NTX has the potential for use in combined therapy with GEN against enterococci and it could further provide a substantial contribution to an ongoing fight against antimicrobial resistance and nosocomial infections.

Risk Factors for 30-Day Mortality in Nosocomial Enterococcal Bloodstream Infections.

Enterococci commonly cause nosocomial bloodstream infections (BSIs), and the global incidence of vancomycin-resistant enterococci (VRE) BSIs is rising. This study aimed to assess the risk factors for enterococcal BSIs and 30-day mortality, stratified by Enterococcus species, vancomycin resistance, and treatment appropriateness. We conducted a retrospective cohort study (2014-2021) including all hospitalized adult patients with at least one blood culture positive for Enterococcus faecalis or Enterococcus faecium. We included 584 patients with enterococcal BSI: 93 were attributed to vancomycin-resistant E. faecium. The overall 30-day mortality was 27.5%; higher in cases of BSI due to vancomycin-resistant E. faecium (36.6%) and vancomycin-sensitive E. faecium (31.8%) compared to E. faecalis BSIs (23.2%) (p = 0.016). This result was confirmed by multivariable Cox analysis. Independent predictors of increased mortality included the PITT score, complicated bacteremia, and age (HR = 1.269, p < 0.001; HR = 1.818, p < 0.001; HR = 1.022, p = 0.005, respectively). Conversely, male gender, consultation with infectious disease (ID) specialists, and appropriate treatment were associated with reduced mortality (HR = 0.666, p = 0.014; HR = 0.504, p < 0.001; HR = 0.682, p = 0.026, respectively). In conclusion, vancomycin-resistant E. faecium bacteremia is independently associated with a higher risk of 30-day mortality.

Clinical characteristics and microbiology of nosocomial enterococcal bloodstream infections in a tertiary-level hospital: a retrospective study, 2007–2019

Enterococci are important pathogens causing nosocomial bloodstream infections (BSIs) and cannot be treated with appropriate timely empirical antibiotics due to their natural resistance to many kinds of antibiotics. To analyse the clinical characteristics and microbiological features of nosocomial bloodstream infections caused by enterococci. The clinical characteristics and microbiological features of nosocomial enterococcal BSI patients in Xiamen University Zhongshan Hospital were examined in a case-controlled retrospective study. All patient information was collected through an electronic surveillance system. A total of 199 cases were identified as nosocomial enterococcal BSIs over a period of 13 years. The incidence of BSIs fluctuated from 0.21% to 0.81%. In the distribution of wards, enterococcal BSIs in hepatobiliary surgery ranked first. Intra-abdominal diseases (odds ratio: 3.36; 95% confidence interval: 2.15-5.27; P < 0.001), chemotherapy history (4.37; 2.06-9.25; P < 0.001), and urinary catheterization (2.34; 1.52-3.61; P < 0.001) were risk factors for nosocomial enterococcal BSI acquisition. Vancomycin-resistant enterococci and linezolid-insensitive enterococci strains were not found. Patients with a history of intra-abdominal disease, chemotherapy and urinary catheterization are at higher risk of nosocomial enterococcal bloodstream infections. The enterococcus strains were still sensitive to commonly used antibiotics.

Molecular characterization of vancomycin-resistant Enterococcus faecium isolates from two German hospitals.

Introduction: Vancomycin-resistant Enterococcus faecium accounts for around 10–23% of nosocomial enterococcal infections and constitutes a relevant therapeutic problem due to its limited susceptibility to antibiotics. The resistance towards glycopeptide antibiotics is mediated by the so-called van genes. Currently, the most common resistance type in Germany is the vanB-type. Little data are available on the molecular epidemiology in Germany. Therefore, an epidemiological typing of Enterococcus faecium isolates with vanB-type resistance from two German hospitals in Essen and Nuremberg was performed. Two outbreaks and 104 sporadic cases were investigated. Methods: All 128 isolates with vanB-type resistance were collected between 2011–2012 and 2017–2018. They were characterized using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Results: ST 117 was the most common sequence type (ST) in both hospitals, especially since 2017. PFGE divided the isolates of this study into 68 PFGE types and showed a broad genetic diversity. Two epidemiologically assumed in-hospital outbreaks were genetically confirmed. Apart from that, in-hospital transmissions were rare events. Conclusion: The results obtained by MLST confirmed the previously described allocation of STs in Germany. PFGE showed a broad genetic diversity of vanB VRE between the two hospitals and also within each hospital. In-hospital transmissions were rare, but outbreaks did occur. Our data supports the strategy to screen and isolate patients in transmission events in order to detect monoclonality indicating a common source or hygiene mismanagement.

Continuous increase of vancomycin resistance in enterococci causing nosocomial infections in Germany − 10 years of surveillance

BackgroundEnterococci are frequent pathogens causing nosocomial infections in Germany. Infections due to strains with vancomycin resistance are high when compared with other European states. Therefore, the study aimed to describe the recent progression of nosocomial infections due to vancomycin-resistant enterococci (VRE) in Germany.MethodsWe analyzed data from two components of the German national nosocomial infection surveillance system for the period 2007–2016. For primary bloodstream infections (BSIs) and urinary tract infections (UTIs) we used data from intensive care units and for surgical site infections (SSIs) data from surgical departments. In a sensitivity analysis, we considered only data from participants that participated continuously from 2007 to 2016 (“core group”). We calculated proportions of VRE among all nosocomial enterococcal infections with 95% confidence intervals (95% CIs) and trends over time. A multivariable logistic regression was used to compare occurrence of VRE proportions among German federal states.ResultsEnterococcal infections from 857 ICUs and 1119 surgical departments were analyzed. On ICUs, the proportion of vancomycin resistance in enterococci causing nosocomial infections significantly increased for BSIs from 5.9 to 16.7% and for UTIs from 2.9 to 9.9%; for surgical site infections, the proportion of VRE increased from 0.9 to 5.2% (P < 0.001 for all). In the core group, the increase of VRE was more pronounced in ICUs (BSIs: 5.5 to 21.6%; UTIs: 2 to 11.2%) but was not seen in surgical departments (SSIs: 1.5 to 2.8%). Compared with the most populous German federal state North Rhine Westphalia, enterococcal infections in Hesse (Odds Ratio (OR) 2.3, 95% CI 1.7–3.1), Saxony (OR 2.5, 95% CI 1.8–3.5) and Thuringia (OR 1.9, 95% CI 1.4–2.6) were more likely to be caused by vancomycin-resistant strains.ConclusionIn Germany, the proportion of VRE in nosocomial infection due to enterococci is still increasing. It remains unclear, why a large variation in the proportion of VRE exists between German federal states.

Characterization of Enterococcus Isolates Colonizing the Intestinal Tract of Intensive Care Unit Patients Receiving Selective Digestive Decontamination.

Enterococci have emerged as important opportunistic pathogens in intensive care units (ICUs). In this study, enterococcal population size and Enterococcus isolates colonizing the intestinal tract of ICU patients receiving Selective Digestive Decontamination (SDD) were investigated. All nine patients included in the study showed substantial shifts in the enterococcal 16S rRNA gene copy number in the gut microbiota during the hospitalization period. Furthermore, 41 Enterococcus spp. strains were isolated and characterized from these patients at different time points during and after ICU hospitalization, including E. faecalis (n = 13), E. faecium (n = 23), and five isolates that could not unequivocally assigned to a specific species (E. sp. n = 5) Multi locus sequence typing revealed a high prevalence of ST 6 in E. faecalis isolates (46%) and ST 117 in E. faecium (52%). Furthermore, antibiotic resistance phenotypes, including macrolide and vancomycin resistance, as well as virulence factor-encoding genes [asa1, esp-fm, esp-fs, hyl, and cyl (B)] were investigated in all isolates. Resistance to ampicillin and tetracycline was observed in 25 (61%) and 19 (46%) isolates, respectively. Furthermore, 30 out of 41 isolates harbored the erm (B) gene, mainly present in E. faecium isolates (78%). The most prevalent virulence genes were asa1 in E. faecalis (54%) and esp (esp-fm, 74%; esp-fs, 39%). Six out of nine patients developed nosocomial enterococcal infections, however, corresponding clinical isolates were unfortunately not available for further analysis. Our results show that multiple Enterococcus species, carrying several antibiotic resistance and virulence genes, occurred simultaneously in patients receiving SDD therapy, with varying prevalence dynamics over time. Furthermore, simultaneous presence and/or replacement of E. faecium STs was observed-, reinforcing the importance of screening multiple isolates to comprehensively characterize enterococcal diversity in ICU patients.

Enterococci in orthopaedic infections: Who is at risk getting infected?

We performed a single-center cohort of adult patients with orthopaedic infections. Among 2740 infection episodes, 665 surgeries (24%) involved osteosynthesis material, including total joint arthroplasties. The recommended perioperative prophylaxis was cefuroxime (or vancomycin in case of documented MRSA body carriage). Patients had received antibiotic therapy before surgery in 1167 episodes (43%); among them with potential anti-enterococcal activity (penicillins, glycopeptides, imipenem, linezolid, daptomycin, aminoglycosids, tetracyclins) in 725 (62%) cases. Overall, enterococci were identified in intraoperative samples of 100 different infections (3.6%) (Enterococcus faecalis, 95; Enterococcus faecium, 2; and other enterococci, 3). However, only 15/100 (15%) enterococcal infections were monomicrobial and 19 were nosocomial (19/2740; 0.7%), of which 15 had previous cephalosporin perioperative prophylaxis without other antibiotic exposure. This association to prior cephalosporin use was significant (Pearson-χ2-test; 148/2640 vs. 15/100, p<0.01). By multivariate analysis, the presence of diabetic foot infection (odds ratio 1.9, 95% confidence interval 1.2-2.9), and polymicrobial infection (OR 6.0, 95%CI 3.9-9.4) were the main predictors of enterococcal infection, while sex, age, and type of material were not. Community-acquired or nosocomial enterococcal infections in orthopaedic surgery are mostly polymicrobial, rare and very seldom attributed to a nosocomial origin. Thus, even if they are formally associated with prior cephalosporin use, we do not see a rational for changing our antibiotic prophylaxis.

Detection of virulence genes in resistant enterococci isolated from pediatric patients at high risk for nosocomial infections

BackgroundThe study of virulence genes carried by enterococci has become of greater relevance as nosocomial enterococcal infections have become more prevalent and possibly more severe. MethodsSurveillance swabs were performed on children less than 18 months of age in an intensive care unit in Iran in 2012–2013. Multiplex PCR and sequencing methods were used to detect gelE, esp and asa1 genes in enterococci with intermediate or full resistance to vancomycin. ResultsThe rate of carriage of the genes was gelE (91%), esp (79%) and asa1 (87%). ConclusionThe majority of enterococcal strains with resistance to vancomycin carry genes for all three potential virulence factors that were analyzed in this study. This might explain why enterococcal infections appear to be more virulent than in the past.

Detection of Enterococcus spp. in bronchoalveolar lavage fluid of patients with high-risk neutropenia: May it be ignored?

We present a series of eight patients with hematological diseases predominantly including AML patients with longlasting neutropenia (Table 1). All patients are characterized by febrile neutropenia, the development of pulmonary infiltrates and comprehensive diagnostic evaluation including bronchoscopy. In all patients, Enterococcus spp. were isolated from bronchoalveolar lavage (BAL), while the majority of these samples contained at least 10,000 bacteria per ml of BAL fluid. Importantly, four out of five Enterococcus strains were characterized by resistance to vancomycin. Thus, half of all BAL specimens were tested positive concerning vancomycin-resistant enterococci (VRE). The consideration of additional BAL findings and the clinical course lead to the assumption that secondary infection with Enterococcus spp. represents the most frequent mechanism how Enterococci can contribute to pneumonia in these immunocompromised patients. In addition, primary infection with E. faecalis was supposed in one of the eight investigated patients. Nevertheless, potential effects of additional antibiotics used in these patients, e.g., empiric antifungal treatment, need to be discussed. Only a few reports on pulmonary infections that are caused by Enterococcus spp. have been published. In detail, in two large analyses of serious enterococcal infections only 4–5 % of patients had pleuropulmonary infections (Garrison et al. 1982; Patterson et al. 1995). This stands remarkably in contrast to our single-center observation of eight cases of nosocomial respiratory enterococcal infections during the last 2 years. We do not query the origin of pulmonary enterococci from resident oropharyngeal flora. In contrast, the relationship between resident Enterococcus spp. and their isolation from BAL has to be reconsidered, especially in such analyses demonstrating a high concentration of bacteria or indicating a potentially relevant resistance profile, e.g., VRE. Dear editor,

Antibiotic resistance pattern of Enterococci isolates from nosocomial infections in a tertiary care hospital in Eastern India.

Background:Resistance to commonly used antibiotics by Enterococci causing nosocomial infections is of concern, which necessitates judicious, responsible and evidence-based use of antibiotics. The present study was conducted to review the prevalence and identify therapeutic options for nosocomial Enterococcal infections in our tertiary care hospital.Materials and Methods:Isolates identified by morphological and biochemical characteristics were tested for antibiotic susceptibility using Kirby-Bauer method.Result:153 of 2096 culture positive clinical samples comprised of 101 urine, 30 wound swab/pus, 13 blood and 09 high vaginal swab isolates were identified as Enterococcus faecalis (90.85%), Enterococcus faecium (8.50%) and Enterococcus gallinarum (0.65%). Enterococci accounted for 8.45%, 4.53%, 4.23%, 4.43% of urinary, wound swab or pus, blood, high vaginal swab isolates respectively, causing 7.3% of all nosocomial infections. Significant number of Enterococci isolated from nosocomial urinary tract infection (66.01%) and wound infections (19.6%) were multidrug resistant (MDR). Although all isolates were sensitive to vancomycin and linezolid, resistance to erythromycin (71.24%) and ciprofloxacin (49.67%) was frequently observed. High-level gentamicin resistance was observed in 43.88%, and 61.53% of E. faecalis and E. faecium isolates respectively. Minimal inhibitory concentration of vancomycin of all the isolates were ≤1 μg/ml. 7% of the Enterococcal isolates were MDR strains and vancomycin or linezolid were the only effective antibiotics.Conclusion:A combination of vancomycin and/or linezolid were effective against Enterococci causing nosocomial infections in our tertiary care facility, nevertheless continuous and frequent surveillance for resistance patterns are necessary for judicious and evidence based use of antibiotics.

Implant Infections Due to Enterococci: Role of Capsular Polysaccharides and Biofilm

Enterococci are natural inhabitants of the gastrointestinal tract and of the female genital tract of humans and many animals. In recent years, enterococci have been increasingly recognized as important human pathogens causing infections associated with medical devices. Their resistance to most antimicrobial agents and their ability to form biofilm has contributed to the increasing incidence of nosocomial enterococcal infections. Enterococci possess a capsular polysaccharide composed of a glycerol-teichoic acid-like molecule consisting of repeating units of 6-alfa-D-glucose-1-2-glycerol-3-PO4 , substituted on carbon 2 with a alfa-2,1-linked molecule of glucose. Using both immunologic and genetic data E. faecalis can be assigned to specific serotypes based on capsular polysaccharides. Clinical examples of foreign-body infections due to enterococci are described, comprising infections of artificial joints, implanted intravascular catheters, artificial hearts and artificial valves, stents, liquor shunt devices, and intraocular infections. Methods to prevent and/or treat enterococcal infections are presented.

Comparison of the incidence of virulence determinants and antibiotic resistance between Enterococcus faecium strains of dairy, animal and clinical origin

Enterococci are part of the dominant microbiota of several dairy products. They are also present in the gut of humans and animals. Their presence in traditional raw milk cheeses is probably due to faecal contamination of milk during milking. Due to their importance as a cause of nosocomial infections, enterococci are acquiring increased significance. Such infections are becoming more and more difficult to treat as resistance to antibiotics increases. The aim of this investigation was to compare the potential virulence of Enterococcus faecium isolated from different ecological habitats and to establish if strains isolated from dairy products should really be considered as potential pathogens. In the present work, the antibiotic resistance pattern of 40 E. faecium strains isolated from dairy products, 26 E. faecium isolated from ewes' faeces and 28 clinical isolates of the same species was studied, and checks were made to see if known virulence determinants were present. Resistance to 12 different antibiotics commonly used in the treatment of human infections was tested using the broth microdilution method as described by the NCCLS. In addition, polymerase chain reaction (PCR) tests were carried out to see if genes for vancomycin resistance were present. The presence of the aggregation substance (AS) gene, the surface protein gene esp, the accessory colonisation factor ace, the Enterococcus faecalis endocarditis antigen efaA and the gelatinase gelE gene, which are involved in the virulence of enterococci, were also tested by PCR. The results of this study clearly indicate that E. faecium strains isolated from both cheese and sheep faeces are less pathogenic than those isolated from clinical samples. A similar pattern of resistance to antibiotics was observed in both dairy and animal strains. It was also found that there was difference in the kind of virulence determinants present in dairy and clinical isolates, while no virulence traits were found in sheep faeces strains. The results of this study suggest that E. faecium from traditional Sardinian raw milk cheeses should not be considered to be the main source of untreatable nosocomial enterococcal infections in humans in the island of Sardinia.

Correlation between enterococcal biofilm formation in vitro and medical-device-related infection potential in vivo.

Hospital-acquired infections caused by enterococci have increased dramatically since the 1970s. Many nosocomial enterococcal bloodstream infections are associated with medical devices such as central venous catheters. The ability to form biofilm on medical devices is a potential virulence trait that may allow enterococci to cause infections in the expanding population of patients managed with such devices. In this study, the hypothesis that increased ability to form biofilm in vitro is associated with medical-device-related infection in vivo was tested. A microplate assay was employed to assess biofilm-forming characteristics of enterococci in 0.9 % (w/v) sodium chloride, an oligotrophic environment, and BHI, a nutrient-rich environment. Results were compared in isolates from different sources of infection. One hundred and nine enterococcal bloodstream isolates were assayed. Biofilm formation on microplates was demonstrated by all Enterococcus faecalis isolates and 16/38 (42 %) Enterococcus faecium isolates. E. faecalis isolates produced significantly more biofilm than E. faecium isolates in both media (P < 0.0001, Mann-Whitney U test). E. faecalis isolates from intravascular-catheter-related bloodstream infections (CRBSIs) produced significantly more biofilm than non-CRBSI isolates (P < 0.0001), or isolates of uncertain clinical significance (P < 0.0001). Biofilm formed by E. faecium isolates was not significantly affected by culture medium and did not differ between isolates from the different clinical categories. In conclusion, there was significantly more biofilm formed by E. faecalis isolates causing CRBSI compared with isolates from other types of infection or from isolates of uncertain clinical significance. The ability of E. faecalis isolates to form biofilm in vitro appears to be a marker of a virulence trait that enhances the ability of isolates to cause CRBSI.

Survival of enterococci during hospital laundry processing

Much remains to be elucidated about the epidemiology of nosocomial enterococcal infections. Enterococci are, however, known to be relatively thermotolerant, and several studies have shown that under laboratory conditions many strains are able to survive the time/temperature combinations of the UK Department of Health recommendations for the decontamination of used linen (HSG(95)18). We therefore wished to investigate the efficacy of decontamination of enterococci from hospital linen in working hospital laundries. The thermotolerance of 40 strains of Enterococcus faecalis and Enterococcus faecium was first determined. Reduction by a factor of greater than 105 was achieved in only two of 40 strains after 3min at 71°C or 10min at 65°C, the time/temperature combinations specified by the Department of Health for the disinfection of used linen. During experimental challenge of 10 working hospital laundries, however, we demonstrated successful decontamination of laundry artificially contaminated with enterococci. This was shown to take place during the washing stage. Our study suggests that, despite the relative thermotolerance of enterococci, the time/temperature combinations specified in HSG(95)18 should be adequate for their decontamination in hospital laundries.

Nosocomial enterococcal infections in children

Objective: To identify factors that are associated with an increased risk of nosocomial enterococcal infection in children.Methods: A matched case-control study was conducted between January 1989 and July 1993 at the Children's National Medical Center, Washington DC. One control patient for each case was identified. Control patients did not have nosocomial enterococcal infections and were matched with cases on the basis of age and time of admission closest to the case within a three-month period. Data were collected from systematic review of patient medical records. One hundred and one study patients (cases) were matched with 101 control patients. A case was defined as a patient with enterococcal infection who met the Centers for Disease Control and Prevention criteria for nosocomial infection. Microbiology methods included isolation, identification, and antimicrobial susceptibility testing of enterococci from clinical specimens.Results: Risk factors associated with nosocomial enterococcal infections were determined by multiple conditional logistic regression analyses of the cases and controls. Factors identified were placement of a central line, gastrointestinal tract pathology, and administration of multiple antimicrobial agents. The median duration of antimicrobial therapy prior to diagnosis of nosocomial enterococcal infection was approximately 1 week.Conclusion: The incidence of nosocomial enterococcal infections in children may be controlled by limiting the number of antimicrobial agents administered to hospitalized high risk patients. Thhe importance of our findings is relevant in an era of increasing rates of antimicrobial resistance in nosocomial enterococcal infections.

Management of infections due to resistant enterococci: a review of therapeutic options.

The incidence of nosocomial enterococcal infection has increased steadily over the past two decades. The treatment of patients with enterococcal infection has been complicated by the emergence of strains possessing high level resistance to aminoglycosides, penicillins and, most recently, glycopeptides. Several recent studies have evaluated alternative antimicrobial agents for use against strains resistant to some or all standard agents. In this report, we review the therapeutic options for the management of antibiotic-resistant enterococcal infection.

Role of Environmental Contamination in the Transmission of Vancomycin-Resistant Enterococci

The acquisition and spread of bacterial resistance to commonly used antibiotics is an ongoing problem in the 1990s.1 Important nosocomial pathogens with an increasing incidence or newly acquired resistance include oxacillin-resistant Staphylococcus aureus, enteric gram-negative bacilli producing extended-spectrum p-lactamase, and vancomycin-resistant Enterococcus species (VRE). Reports of VRE began to appear in the mid-1980s in Europe and are now an important problem in an evergrowing number of hospitals in the United States. Data accumulated via the National Nosocomial Infection Surveillance (NNIS) system of the Centers for Disease Control and Prevention (CDC) revealed that VRE increased 35-fold among all nosocomial isolates of enterococci (0.3% to 10.4%) between 1989 and 1995.2 By 1994 and 1995, 41% of all NNIS hospitals reported at least one nosocomial enterococcal infection. A recent report notes that attributable mortality is approximately 40%.3 Because of the importance of VRE as a nosocomial pathogen, the Hospital Infection Control Practices Advisory Committee (HICPAC) of the CDC has published guidelines for preventing nosocomial transmission.4 Among the important scientific questions regarding nosocomially acquired VRE are the following. First, do patients colonized or infected with VRE contaminate their environment? Second, what is the role of surface contamination in the transmission of VRE? Third, is surface contamination linked to the transmission of other nosocomial pathogens? Finally, what scientifically based policies can infection control professionals adopt to prevent or reduce nosocomial transmission of these pathogens? Several investigators have studied the frequency of environmental contamination found in the rooms of patients with VRE.11 Cultures of the surface environment yielded VRE in 7% to 37% of samples (Table). These investigations also produced several other important findings. Boyce et al reported that environmental contamination was more widespread in the rooms of patients with diarrhea6 (Table). In a later study, Boyce et al reported that the disposable gowns of nurses who cared for a patient with copious diarrhea also were contaminated with VRE.8 Montecalvo et al reported that 8% of cultures taken after terminal cleaning still yielded VRE.7 Molecular analysis of VRE strains has demonstrated both multiple circulating strains9,1112 and outbreaks due to a single strain.6,8,12,13 In some cases, isolates obtained from the environment were identical to the epidemic strain causing infection.6'8 However, in these outbreaks, it often has been difficult to determine whether cross-transmission occurred due to contaminated common equipment (eg, stethoscopes), acquisition of transient hand carriage by

Pseudo-outbreak of Enterococcus durans infections and colonization associated with introduction of an automated identification system software update.

Enterococci are an important cause of hospital-acquired infections. Since 1989, there has been an increase in the number of nosocomial enterococcal infections caused by strains resistant to vancomycin in the United States. Although many enterococcal species can colonize humans, only Enterococcus faecalis, E. faecium, E. raffinosus, and E. casseliflavus have been implicated in clusters of infection. In January 1996, the Centers for Disease Control and Prevention received a report of an outbreak of vancomycin-resistant enterococci in which 31 of 84 (36.9%) isolates were identified as E. durans. Twenty-nine isolates identified as E. durans were identified to the species level after the introduction of an automated identification system software update (Vitek gram-positive identification card, version R09.1) for the identification of species of gram-positive organisms. When seven isolates initially reported as E. durans were identified to the species level by alternate methods, they were found to be E. faecium. Subsequently, isolates identified as E. durans by the automated system were reidentified by using a rapid streptococcus test, and no further enterococcal isolate has been confirmed as E. durans. Automated microbial analysis is a potential source of error that is not easily recognized. When laboratory findings are discordant with expected clinical or epidemiologic patterns, confirmatory testing by alternate methods should be performed.

Treatment of vancomycin-resistant enterococci, with a focus on quinupristin-dalfopristin.

Enterococci are the second most common cause of hospital-acquired infections, and drug resistance among these organisms is a growing problem. Vancomycin-resistant enterococci (VRE) now account for 7.9% of the nosocomial enterococcal infections. There is no standard therapy for VRE. Although some agents have shown in vitro activity alone or in combination, including ciprofloxacin, doxycycline, novobiocin, teicoplanin, chloramphenicol, and rifampin, treatment options are limited to combinations of drugs with marginal efficacy against the pathogens. Quinupristin-dalfopristin is a new investigational agent with activity against gram-positive cocci, including VRE.

Enterococcal Nosocomial Infection

Caring for patients susceptible to enterococcal infections is a part of practice for nurses working in today's hospital units. While enterococci are not particularly virulent organisms, they are well suited to causing infection in hospitalized patients, especially in the very old, the seriously ill, and the immunosuppressed. Despite increased understanding of the clinical threat posed by multiresistant strains of enterococci, the incidence of nosocomial enterococcal infection is growing. In this article the author examines the epidemiology and risk factors for colonization and infection with enterococcal bacteria and provides a brief review of antibiotic sensitivities for the organisms. A case study illustrates the course and consequence of infection with multiresistant enterococcus for the seriously ill patient. The importance of education of health professionals in prevention and control of enterococcal infection and superinfection is discussed.