Prolonged colonization with vancomycin-resistant Enterococcus faecium in long-term care patients and the significance of "clearance"

Control of vancomycin-resistant enterococci in a hospital: a five-year experience in a Taiwanese teaching hospital

In order to prevent transmission of hospital-acquired vancomycin-resistant enterococci (VRE), the infection control team (ICT) of the National Taiwan University Hospital (NTUH) introduced practical guidelines from January 1997 to June 2000. All patients at NTUH found to be infected or colonized with VRE were placed in strict contact and cohort isolation. Surveillance cultures were obtained from other patients in close proximity in order to determine any spread of VRE. If identified, these patients were also placed in contact and cohort isolation, and their isolates were subjected to antimicrobial susceptibility testing and molecular typing by pulsed-field gel electrophoresis. During this period, 20 patients were found to have VRE. Based on typing results, there were three occasions where the same VRE strain had spread between index patients and roommates or patients staying in neighbouring rooms. No further spread occurred after applying strict contact isolation for these patients. The hospital-acquired VRE infection rate was around 0.03 to 0.09 per 1000 discharges during the intervention period. After July 2000, however, members of the ICT did not actively monitor or implement any interventions to control VRE. The rate then increased to 0.20 per 1000 discharges in 2001. This study suggests that interventions for the control of VRE, based on the guidelines from the Hospital Infection Control Practice Advisory Committee, are effective for control of VRE spread. Failure to adhere to these guidelines may result in an increase in hospital-acquired VRE.

Debate—Guidelines for control of glycopeptide-resistant enterococci (GRE) have not yet worked

Glycopeptide-resistant enterococci (GRE) have become a focus of concern in many countries because options for antimicrobial therapy of GRE infection are limited. Several guidelines for the control and prevention of GRE colonization and infection have been developed for healthcare settings, and occasional journal articles now report "control" (usually relative reduction of incidence or prevalence rate rather than elimination) of GRE infections. Yet, rates of infection and colonization with GREcontinue to climb in many parts of the world, showing that true control has not been achieved. Programmes to control GRE will be effective only when they (1) are less expensive to implement; (2) are shown to be cost-effective despite the fact that they merely reduce prevalence levels rather than eradicating the problem; (3) do not require almost perfect implementation to be effective; (4) are shown to be sustainable; (5) are shown to work in acute-care settings other than selected academic centres; and (6) are shown to work in non-acute care settings. Until then, it is clear that guidelines for control of GRE have not worked. New guidelines that truly control GRE must be developed, and this must be done quickly.

Antimicrobial resistance: is it really that bad?

Antimicrobial resistance has been the subject of this and numerous other special issues of pediatric and infectious disease journals during the past several years. Pediatricians may be forgiven for expressing skepticism occasionally about dour scenarios predicting the advent of untreatable infections or a return to the preantibiotic era. Certainly, some benefits may accrue to pharmaceutical companies, academic and public health experts, and managed care systems from promoting concern about antimicrobial resistance. In fact, the response to the spread of resistance has been forceful, and in some cases successful, with reductions achieved in unnecessary prescribing, treatment regimens modified, and some new antimicrobial agents made available during the past several years. The problem, however, remains substantial, as several clear examples of dangerous and nearly untreatable multiply resistant organisms exist and the costs associated with treating resistant organisms continue to skyrocket. In many instances in the developing world, antimicrobial resistance can mean that a formerly treatable infection has become untreatable, and for pediatricians in the United States, resistance has, at the least, complicated therapy and limited options in everyday practice.

Detection of Vancomycin‐Resistant Enterococci Before and After Antimicrobial Therapy: Use of Conventional Culture and Polymerase Chain Reaction

Antimicrobial therapy can increase the colonization density of gastrointestinal vancomycin-resistant enterococci (VRE). Among previously VRE-colonized patients, we evaluated VRE colonization before and after initiation of antimicrobial therapy by means of polymerase chain reaction (PCR) and culture. Perianal swab samples were obtained at admission to the hospital and after receipt of antimicrobial therapy. At admission, 12 (21%) of 56 patients were culture positive, and 17 (30%) had vanA or vanB genes detected by PCR. Culture results showed that 25 (86%) of 29 culture-negative patients from whom a second swab sample was obtained remained culture negative, 2 (6.9%) had a relapse of colonization with a strain related to the previously colonizing strain type (2 and 6 days after admission), and 2 (6.9%) tested positive for a previously undetected strain type (16 and 19 days after admission). PCR at admission detected VRE in 1 of the 2 patients who later relapsed. Patients with negative results of culture of the initial swab sample and of PCR were unlikely to relapse after receipt of antimicrobial therapy.

Persistent colonization and the spread of antibiotic resistance in nosocomial pathogens: resistance is a regional problem

Infections with antibiotic-resistant bacteria (ARB) in hospitalized patients are becoming increasingly frequent despite extensive infection-control efforts. Infections with ARB are most common in the intensive care units of tertiary-care hospitals, but the underlying cause of the increases may be a steady increase in the number of asymptomatic carriers entering hospitals. Carriers may shed ARB for years but remain undetected, transmitting ARB to others as they move among hospitals, long-term care facilities, and the community. We apply structured population models to explore the dynamics of ARB, addressing the following questions: (i) What is the relationship between the proportion of carriers admitted to a hospital, transmission, and the risk of infection with ARB? (ii) How do frequently hospitalized patients contribute to epidemics of ARB? (iii) How do transmission in the community, long-term care facilities, and hospitals interact to determine the proportion of the population that is carrying ARB? We offer an explanation for why ARB epidemics have fast and slow phases and why resistance may continue to increase despite infection-control efforts. To successfully manage ARB at tertiary-care hospitals, regional coordination of infection control may be necessary, including tracking asymptomatic carriers through health-care systems.

Acquisition and duration of vancomycin-resistant enterococcal carriage in relation to strain type

In May 2000, the first outbreak of vancomycin-resistant Enterococcus faecium (VREF) was detected in the University Medical Center Utrecht in the nephrology ward. The question arose why some VREF strains spread among hospitalized patients, whereas other strains do not. Thirty patients who were found to be colonized with VREF between May and November 2000 were included in the study. Molecular typing confirmed that 19 of them carried an identical epidemic strain which harbored the esp gene while 11 were colonized by nonepidemic strains that were all esp negative. Acquisition of the outbreak strain was significantly associated with diabetes mellitus, renal transplantation, and extensive use of antibiotics, especially cephalosporins, in the 2-month period before the first isolation of VREF. To establish the duration of colonization, prospective surveillance of VREF carriage for a 6-month period starting from the first isolation of VREF was realized for 20 patients. After 6 months, VREF was still recovered from 60% of carriers of the outbreak strain versus 20% of carriers of nonepidemic strains (P < 0.01). However, antibiotic use during the follow-up period was significantly higher by carriers of the outbreak strain than by carriers of nonepidemic strains. The fact that the outbreak strain was recovered for a longer period of time than nonepidemic strains may facilitate dissemination of the strain. The results support a careful restrictive antibiotic policy for wards at risk for spread of VREF and implementation of isolation precautions for patients who are colonized with esp-positive outbreak strains.

Prosthetic valve endocarditis due to vancomycin-resistant Enterococcus faecium: treatment with chloramphenicol plus minocycline

We report a case of prosthetic valve endocarditis and persistent bacteremia due to vancomycin-resistant Enterococcus faecium. The combination of parenteral chloramphenicol plus minocycline therapy was administered for 8 weeks and resulted in cure after treatment with quinupristin-dalfopristin had failed.

Molecular characterization of vancomycin-resistant Enterococci repopulating the gastrointestinal tract following treatment with a novel glycolipodepsipeptide, ramoplanin

We characterized baseline and repopulating stool isolates recovered during a phase II trial of ramoplanin for the treatment of patients with stool carriage of vancomycin-resistant enterococci (VRE). Repopulation with a strain with a related genotype was found in 74, 60, and 53% of individuals in groups treated with placebo, 100 mg of ramoplanin, and 400 mg of ramoplanin, respectively. All ramoplanin-treated patients with a culture positive for VRE at day 7 had a relapse caused by a genotypically related isolate. In ramoplanin-treated patients, antibiotics with activities against anaerobic organisms were associated with positive cultures on day 7 (relative risk [RR] = 8.8; P = 0.004), and the avoidance of such antibiotics was significantly associated with culture negativity through day 21 (RR = 0.16; P = 0.02).