The Role of "Colonization Pressure" in the Spread of Vancomycin-Resistant Enterococci

Vancomycin-resistant enterococci (VRE) are relevant nosocomial pathogens with an increasing incidence in the last decades. Their transmission is optimal in the hospital setting, as it offers two potential, large reservoirs that are closely related: susceptible patients and their environment. Here we investigate the role of the hospital environment in the nosocomial transmission of VRE by establishing concrete links between contaminated surfaces and colonized/infected patients in outbreak and non-outbreak settings. Environmental and patient VRE isolates were collected between 2013 and 2019 and analyzed by whole-genome sequencing (WGS), subsequent multilocus sequence typing (MLST), and core genome (cg) MLST. Pairs of isolates differing in <3 alleles were rated as closely related, making a transmission likely. Fifty-three environmental VRE isolates were analyzed. MLST sequence types (ST) ST203 (50.0%), ST192 (21.3%), ST117 (17.3%), ST721 (8.8%), ST80 (2%), and ST1489 (0.7%) were detected, carrying the resistance determinants vanA (72.7%), vanB (24%), or both (3.3%). Of the 53 environmental isolates, 51 were found to form five clusters with genetically related patient isolates (n = 97 isolates). WGS confirms the role of the environment in the transmission dynamics of VRE in both the outbreak and non-outbreak settings, highlighting the importance of prevention and control of VRE spread.

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Antimicrobial-Resistant Gram-Positive Bacteria in PD Peritonitis and the Newer Antibiotics Used to Treat Them

Peritoneal Dialysis International ◽

10.1177/089686080502500402 ◽

2005 ◽

Vol 25 (4) ◽

pp. 313-319 ◽

Cited By ~ 21

Author(s):

William Salzer

Keyword(s):

Methicillin Resistant Staphylococcus Aureus ◽

Natural Habitat ◽

Gram Positive ◽

Gram Positive Bacteria ◽

The Past ◽

Vancomycin Resistant Enterococci ◽

Resistant Strains ◽

Vancomycin Resistant ◽

Novel Antibiotics

The incidence of resistant gram-positive bacteria in nosocomial and, more recently, community-acquired infections is increasing. Staphylococci, because of their natural habitat on the skin, have always been the leading cause of peritonitis in patients receiving peritoneal dialysis (PD). These organisms have demonstrated a remarkable ability to develop resistance to antibiotics, first with penicillin, then antistaphylococcal penicillins (methicillin-resistant Staphylococcus aureus), and more recently, strains expressing resistance to vancomycin (vancomycin-intermediate and vancomycin-resistant S. aureus) have emerged. Enterococci are normal inhabitants of the gastrointestinal tract and occasionally cause PD peritonitis. In the past 15 years, vancomycin-resistant enterococci have emerged as significant pathogens in many areas. In the past 5 years, novel antibiotics that have activity on gram-positive bacteria, including vancomycin-resistant strains, have become available. The problem of resistant gram-positive bacteria in PD peritonitis, their therapy, and the role of these newer agents, quinupristin/dalfopristin, linezolid, and daptomycin, are reviewed.

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Antibiotic Exposure and Room Contamination Among Patients Colonized With Vancomycin-Resistant Enterococci

Infection Control and Hospital Epidemiology ◽

10.1086/589582 ◽

2008 ◽

Vol 29 (8) ◽

pp. 709-715 ◽

Cited By ~ 30

Author(s):

Marci Drees ◽

David R. Snydman ◽

Christopher H. Schmid ◽

Laurie Barefoot ◽

Karen Hansjosten ◽

...

Keyword(s):

Confidence Interval ◽

Antibiotic Use ◽

Hazard Ratio ◽

Adjusted Hazard Ratio ◽

Care Hospital ◽

Antibiotic Exposure ◽

Colonization Pressure ◽

Vancomycin Resistant Enterococci ◽

Significant Difference ◽

Vancomycin Resistant

Objective.To determine whether total and antianaerobic antibiotic exposure increases the risk of room contamination among vancomycin-resistant enterococci (VRE)–colonized patients.Design And Setting.A 14-month study in 2 intensive care units at an academic tertiary care hospital in Boston, Massachusetts.Patients.All patients who acquired VRE or were VRE-colonized on admission and who had environmental cultures performed.Methods.We performed weekly environmental cultures (2 sites per room) and considered a room to be contaminated if there was a VRE-positive environmental culture during the patient's stay. We determined risk factors for room contamination by use of the Cox proportional hazards model.Results.Of 142 VRE-colonized patients, 35 (25%) had an associated VRE-positive environmental culture. Patients who contaminated their rooms were more likely to have diarrhea than those who did not contaminate their rooms (23 [66%] of 35 vs 41 [38%] of 107;P= .005) and more likely to have received antibiotics while VRE colonized (33 [94%] of 35 vs 86 [80%] of 107;P= .02). There was no significant difference in room contamination rates between patients exposed to antianaerobic regimens and patients exposed to nonantianaerobic regimens or between patients with and patients without diarrhea, but patients without any antibiotic exposure were unlikely to contaminate their rooms. Diarrhea and antibiotic use were strongly confounded; although two-thirds of room contamination occurred in rooms of patients with diarrhea, nearly all of these patients received antibiotics. In multivariable analysis, higher mean colonization pressure in the ICU increased the risk of room contamination (adjusted hazard ratio per 10% increase, 1.44 [95% confidence interval, 1.04–2.04]), whereas no antibiotic use during VRE colonization was protective (adjusted hazard ratio, 0.21 [95% confidence interval, 0.05–0.89]).Conclusions.Room contamination with VRE was associated with increased mean colonization pressure in the ICU and diarrhea in the VRE-colonized patient, whereas no use of any antibiotics during VRE colonization was protective.

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Persistent environmental reservoirs for Vancomycin-resistant enterococci requiring repeated decontamination to achieve eradication

British Journal of Infection Control ◽

10.1177/175717740200300303 ◽

2002 ◽

Vol 3 (3) ◽

pp. 10-13 ◽

Cited By ~ 3

Author(s):

T Sexton ◽

E Creamer ◽

M Turley ◽

E Smyth ◽

E Humphreys

Keyword(s):

Daily Basis ◽

Control Measures ◽

Vancomycin Resistant Enterococci ◽

Cleaning Equipment ◽

Hospital Infection Control ◽

Vancomycin Resistant ◽

Environmental Measures ◽

And Control ◽

Predominant Strain

V ancomycin-resistant enterococci (VRE) are increasingly recognised nosocomial pathogens in clinical areas with high antibiotic usage. Patients with chronic renal failure, including those requiring haemodialysis, are at particular risk. Investigation and control of an outbreak of VRE in two renal wards, highlighting mattresses as reservoirs and environmental measures to control VRE are reported in this paper. Outbreak control measures included standard isolation in accordance with the Recommendations of the Hospital Infection Control Practices Advisory Committee (HICPAC). Patients were screened on admission and weekly using a rectal swab. The inanimate environment including mattresses was also screened. Enhanced environmental decontamination was performed on a daily basis. The outbreak continued over a 20-week period with most cases occurring in the first 6 weeks. The results of screening indicated that 59 (13%) of 451 patients and 54 (8.3%) of 647 environmental samples were positive for VRE. VRE was isolated from 35 (8%) of 433 mattresses, 12 (8.1%) of 148 environmental ledges, 4 (8%) of 50 toilets, and 3 (18.8%) of 16 items of cleaning equipment. Molecular typing indicated that a predominant strain was also implicated in mattress contamination, thus highlighting a potential and important reservoir for transmission of VRE. Difficulty with eradication of VRE from the environment was encountered despite enhanced cleaning regimens and a doubling of use of disinfectant was necessary. Restriction of antibiotics, hand hygiene, hygiene and education are the cornerstone of VRE prevention and control. Lessons from this outbreak highlight the role of the environment in VRE transmission and the need for attention to the environment, especially mattress decontamination.

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