Surveillance and endemic vancomycin-resistant enterococci: some success in control is possible

Protracted transmission and persistence of ST80 vancomycin-resistant Enterococcus faecium clonal complex types CT2933, CT2932 and CT1916 in a large Irish hospital: a 39-month whole-genome sequencing study

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VREfm) are significant nosocomial pathogens. Sequence type (ST) 80 vanA-encoding VREfm predominate in Irish hospitals, but their transmission is poorly understood.

AIMS

To investigate transmission and persistence of predominant complex type (CT) VREfm in two wards of an Irish hospital (H1) using whole-genome sequencing, and their intra- and inter-hospital dissemination.

METHODS

Rectal screening (N = 330, September 2019 to December 2022) and environmental (N = 48, November 2022 to December 2022) E. faecium were investigated. Isolate relatedness was assessed by core-genome multi-locus sequence typing (cgMLST) and core-genome single nucleotide polymorphism (cgSNP) analysis. Likely transmission chains were identified using SeqTrack (https://graphsnp.fordelab.com/graphsnp) using cgSNP data and recovery location. Well-characterized E. faecium (N = 908) from seven Irish hospitals including H1 (June 2017 to July 2022) were also investigated.

FINDINGS

Conventional MLST assigned isolates to nine STs (ST80, 82%). cgMLST identified three predominant ST80 CTs (CT2933, CT2932 and CT1916) (55% of isolates) of related isolates (≤20 allelic differences). cgSNP analysis differentiated these CTs into multiple distinct closely related genomic clusters (≤10 cgSNPs). Parisimonious network construction identified 55 likely inter- and intra-ward transmissions with epidemiological support between patients ≤30 days involving 73 isolates (≤10 cgSNPs) from seven genomic clusters. Numerous other likely transmissions over longer time periods without evident epidemiological links were identified, suggesting persistence and unidentified reservoirs contribute to dissemination. The three CTs predominated among E. faecium (N = 1286) in seven hospitals, highlighting inter-hospital spread without known epidemiological links.

CONCLUSION

This study revealed the long-term intra- and inter-hospital dominance of three major CT ST80 VREfm lineages, widespread transmission and persistence, implicating unidentified reservoirs.

A systematic review of the effectiveness of cohorting to reduce transmission of healthcare-associated C. difficile and multidrug-resistant organisms

BACKGROUND

Cohorting of patients and staff is a control strategy often used to prevent the spread of infection in healthcare institutions. However, a comprehensive evaluation of cohorting as a prevention approach is lacking.

METHODS

We performed a systematic review of studies that used cohorting as part of an infection control strategy to reduce hospital-acquired infections. We included studies published between 1966 and November 30, 2019, on adult populations hospitalized in acute-care hospitals.

RESULTS

In total, 87 studies met inclusion criteria. Study types were quasi-experimental "before and after" (n = 35), retrospective (n = 49), and prospective (n = 3). Case-control analysis was performed in 7 studies. Cohorting was performed with other infection control strategies in the setting of methicillin-resistant Staphylococcus aureus (MRSA, n = 22), Clostridioides difficile infection (CDI, n = 6), vancomycin-resistant Enterococcus (VRE, n = 17), carbapenem-resistant Enterobacteriaceae infections (CRE, n = 22), A. baumannii (n = 15), and other gram-negative infections (n = 5). Cohorting was performed either simultaneously (56 of 87, 64.4%) or in phases (31 of 87, 35.6%) to help contain transmission. In 60 studies, both patients and staff were cohorted. Most studies (77 of 87, 88.5%) showed a decline in infection or colonization rates after a multifaceted approach that included cohorting as part of the intervention bundle. Hand hygiene compliance improved in approximately half of the studies (8 of 15) during the respective intervention.

CONCLUSION

Cohorting of staff, patients, or both is a frequently used and reasonable component of an enhanced infection control strategy. However, determining the effectiveness of cohorting as a strategy to reduce transmission of MDRO and C. difficile infections is difficult, particularly in endemic situations.

Gastrointestinal Carriage of Vancomycin-Resistant Enterococci and Carbapenem-Resistant Gram-Negative Bacteria in an Endemic Setting: Prevalence, Risk Factors, and Outcomes

Background: Gastrointestinal carriage of vancomycin-resistant enterococci (VRE) and carbapenem-resistant Gram-negative bacteria (CRGN) constitutes a major public health concern as it may be followed by clinical infection development or lead to intra-hospital dissemination. Detection of carriers and implementation of infection control measures are essential in every hospital. In this study we determined the point prevalence of VRE and CRGN in the fecal flora of the inpatients of a tertiary university hospital in Greece. We determined risk factors for carriage and examined the impact of carriage on hospital outcomes. Materials/Methods: A point prevalence study of VRE/CRGN rectal carriage of inpatients was conducted on March 2018. Specimens were selectively cultured for VRE/CRGN, microorganisms were biochemically identified, submitted to antibiotic susceptibility testing, and tested for carbapenemase production. Data on potential risk factors and hospital outcomes were collected at the time of culture and until hospital discharge. Multivariable logistic and linear regression models were used, adjusting for confounders. Results: Four hundred ninety-one patients were enrolled in the study. Of them, 64 (13.0%) were positive for VRE carriage, 40 (8.2%) for CRGN, and 10 patients (2.1%) for both VRE and CRGN. VRE carriage was independently associated with age over 65 years (adjusted OR: 2.4 [95%CI: 1.3, 4.5]) and length of stay (LOS) before rectal sampling (OR: 1.1 [95%CI: 1.0, 1.1]). Carriage of CRGN was associated with 11 days increase of LOS after rectal sampling (β-coef: 11.4 [95%CI: 1.6, 21.2]), with a 3.5-fold increased risk of acquiring a resistant pathogen after rectal swabbing (RR: 3.5 [95%CI 1.2, 9.9]) and with a 6-fold increased risk of mortality (RR: 6.1 [95%CI: 2.1, 17.9]), after adjusting for sex, age, and comorbidity index. Conclusions: High prevalence rates were found for VRE and CRGN carriage among the inpatients of our hospital. Prolonged hospitalization and age were independent risk factors for VRE carriage, while CRGN carriage was associated with increased risk of acquiring a resistant pathogen, prolonged hospital stay, and increased mortality.

Epidemiology and risk factors of methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci infections in Zhejiang China from 2015 to 2017

Background

Gram-positive bacteria are dangerous and challenging agents of infection due to their increasing resistance to antibiotics. We aim to analyse the epidemiology and risk factors of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) in Zhejiang China.

Methods

Gram-positive bacteria (including S. aureus, Enterococcus faecalis and Enterococcus faecium) were collected from eighty-six hospitals of eleven cities in Zhejiang China from 2015 to 2017. The detection rates of MRSA and VRE infection were calculated for the non-duplicated isolate according to year, region, hospital level, patient age, specimen type and patient category. Meanwhile, the detected resistances of MRSA, E. faecalis and E. faecium to different antibiotics from 2015 to 2017 were compared. The risk factors and the differences in MRSA and VRE detection rates were compared using odds ratio (OR) with 95% confidence interval (95% CI) and Chi-square test respectively.

Results

From 2015 to 2017, the detection rates of MRSA and VRE decreased gradually. The cities with the highest MRSA and VRE detection rates tended to be adjacent; for example, the neighbouring cities Hangzhou and Quzhou had simultaneously high rates of MRSA and VRE infection. Patients from IIIA hospital who were older than 75 years and in the intensive care unit (ICU) were most at risk. No vancomycin-resistant isolate was found in MRSA. Resistance of E. faecalis and E. faecium to vancomycin and linezolid decreased slightly and then maintained a low level.

Conclusions

The detection rates of MRSA and VRE stayed at moderate and low levels during the three year period of this study, while local dissemination was found in MRSA and VRE isolates. Sustained surveillance is necessary to prevent the spread or clonal dissemination of drug-resistant strains in Zhejiang China.

MiBAlert-a new information tool to fight multidrug-resistant bacteria in the hospital setting

BACKGROUND

Although the timely isolation of patients is an essential intervention to limit spread of drug-resistant bacteria, information about the colonization status is often unavailable or lost when patients are readmitted or transferred between hospitals. Therefore, carriers of drug resistant bacteria are not recognized sufficiently early, and proper and timely isolation precautions are not taken. Consequently, resistant bacteria of public health concerns including vancomycin resistant enterococci (VRE) and methicillin resistant Staphylococcus aureus (MRSA) can spread epidemically. To ensure timely identification and proper isolation of such patients we developed an automatic real-time alert of carriers of drug resistant bacteria.

OBJECTIVES

The aim of this paper is to describe the system, called MiBAlert, and share the initial experiences in connection with an outbreak of VRE in the greater Copenhagen area (the Capital region), Denmark.

METHODS

We obtained data on cases of VRE from hospitals in Copenhagen during the period when the first version of MiBAlert was implemented and log-data on the use of MiBAlert. Furthermore, a survey was conducted among 88 staff members to investigate their experiences of MiBAlert.

RESULTS

The alert is a tool directed toward healthcare personnel accessing the electronic health record (EHR) and those further involved in the care and treatment of the patient. It is based on a web service using data from the national microbiological database, MiBa. MiBAlert is a real-time electronic non-intrusive alert generated automatically in the header of the EHR each time record is accessed. On February 15, 2015 a pilot version of MiBAlert was launched. All positive tests for VRE throughout 1year were shown with alert status by MiBAlert visible to all medical staff with access to EHR. The alert system was automatically updated directly in the EHR across the five hospitals in the Capital region. We found that the system performed satisfactorily, being operational 24/7 all 135 trial days, apart from 72min, for all the hospitals. Of the staff who responded to the survey, 82% considered that MiBAlert overall improved compliance with isolation precautions regarding VRE-positive patients. We found a marked decline of new patients infected or colonized with VRE concomitant with the implementation of MiBAlert and the survey results.

CONCLUSION

We found that MiBAlert was a valuable tool in a bundle approach to counter a multiple hospital outbreak of VRE, and that it has a great potential to improve the control of other drug-resistant bacteria.

Impact of vancomycin-resistant enterococci colonization in critically ill pediatric patients

BACKGROUND

We aimed to determine the frequency of vancomycin-resistant enterococci (VRE) infection occurrence in previously VRE-colonized children in a pediatric intensive care unit (PICU) and to identify associated risk factors.

METHODS

Infection control nurses have performed prospective surveillance of health care-associated infections and rectal VRE carriage in PICUs from January 2010-December 2014. This database was reviewed to obtain information about VRE-colonized and subsequently infected patients. A case-control study was performed to identify risk factors associated with VRE infection development in previously VRE-colonized patients.

RESULTS

Out of 1,134 patients admitted to the PICU, 108 (9.5%) were found to be colonized with VRE throughout the study period. Systemic VRE infections developed in 11 VRE-colonized patients (10.2%), and these included primary bloodstream infection (n = 6), urinary tract infection (n = 3), meningitis and bloodstream infection (n = 1), and meningitis (n = 1). Logistic regression analysis indicated long hospital stay (≥30 days) and glycopeptide use after detection of VRE colonization as risk factors for developing VRE infection in VRE-colonized patients (odds ratio [OR], 5.76; 95% confidence interval [CI], 1.6-15.8; P = .017 and OR, 12.8; 95% CI, 1.9-26.6; P = .012, respectively).

CONCLUSIONS

VRE colonization has important consequences in pediatric critically ill patients. Strict infection control measures should be implemented to prevent VRE colonization and thereby VRE infections. Furthermore, irrational antibiotic use and particularly glycopeptide use in VRE-colonized patients should be restricted.

Epidemiology and molecular typing of VRE bloodstream isolates in an Irish tertiary care hospital

OBJECTIVES

Ireland has the highest rate of vancomycin-resistant Enterococcus faecium (VREfm) isolated from blood of nosocomial patients in Europe, which rose from 33% (110/330) in 2007 to 45% (178/392) in 2012. No other European country had a VREfm rate from blood cultures of >25%. Our aim was to elucidate the reasons for this significantly higher rate in Ireland.

METHODS

The epidemiology and molecular typing of VRE from bloodstream infections (BSIs) was examined in a tertiary care referral hospital and isolates were compared with those from other tertiary care referral centres in the region.

RESULTS

The most common source of VRE BSIs was intra-abdominal sepsis, followed by line-related infection and febrile neutropenia. Most of the isolates were positive for vanA; 52% (43/83) possessed the esp gene and 12% (10/83) possessed the hyl gene. Genotyping by SmaI macrorestriction analysis (PFGE) of isolates revealed clonal relatedness between bloodstream isolates and environmental isolates. VRE BSI isolates from two other tertiary care hospitals in the Dublin region showed relatedness by PFGE analysis. MLST revealed four STs (ST17, ST18, ST78 and ST203), all belonging to the clonal complex of hospital-associated strains.

CONCLUSIONS

Irish VRE BSI isolates have virulence factor profiles as previously reported from Europe. Typing analysis shows the spread of individual clones within the hospital and between regional tertiary care hospitals. Apart from transmission of VRE within the hospital and transfer of colonized patients between Irish hospitals, no other explanation for the persistently high VREfm BSI rate in Ireland has been found.

Carbapenem-ResistantKlebsiella pneumoniaein Post-Acute-Care Facilities in Israel

Objective.

To assess the prevalence of and risk factors for carbapenem-resistantKlebsiella pneumoniae(CRKP) carriage among patients in post-acute-care facilities (PACFs) in Israel.

Design, Setting, and Patients.

A cross-sectional prevalence survey was conducted in 12 PACFs. Rectal swab samples were obtained from 1,144 patients in 33 wards. Risk factors for CRKP carriage were assessed among the cohort. Next, a nested, matched case-control study was conducted to define individual risk factors for colonization. Finally, the cohort of patients with a history of CRKP carriage was characterized to determine risk factors for continuous carriage.

Results.

The prevalence of rectal carriage of CRKP among 1,004 patients without a history of CRKP carriage was 12.0%. Independent risk factors for CRKP carriage were prolonged length of stay (odds ratio [OR], 1.001;P< .001), sharing a room with a known carrier (OR, 3.09;P= .02), and increased prevalence of known carriers on the ward (OR, 1.02;P= .013). A policy of screening for carriage on admission was protective (OR, 0.41;P= .03). Risk factors identified in the nested case-control study were antibiotic exposure during the prior 3 months (OR, 1.66;P= .03) and colonization with other resistant pathogens (OR, 1.64;P= .03). Among 140 patients with a history of CRKP carriage, 47% were colonized. Independent risk factors for continued CRKP carriage were antibiotic exposure during the prior 3 months (OR, 3.05;P= .04), receipt of amoxicillin-clavulanate (OR, 4.18;P= .007), and screening within 90 days of the first culture growing CRKP (OR, 2.9;P= .012).

Conclusions.

We found a large reservoir of CRKP in PACFs. Infection-control polices and antibiotic exposure were associated with patient colonization.

To swab or not to swab? A prospective analysis of 341 SICU VRE screens

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) screening is routine practice in many intensive care units despite the question of its clinical significance. The value of VRE screening at predicting subsequent VRE or other hospital-acquired infection (HAI) is unknown. The purpose of this investigation was to examine the rate of subsequent VRE HAI in patients undergoing VRE screening.

METHODS

This study was conducted in a 24-bed surgical intensive care unit (SICU) at a Level I trauma center. Patients admitted to the SICU between February and August 2011 who had rectal swab for VRE screening within 72 hours were followed prospectively for the development of VRE and other HAIs. Demographics, clinical characteristics, and infection rates were compared between VRE-positive and VRE-negative patients. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of VRE screening for predicting subsequent VRE HAI were calculated.

RESULTS

A total of 341 patients had VRE screening within 72 hours of SICU admission, with 32 VRE-positive (9%) and 309 VRE-negative (91%) patients. VRE-positive patients had a higher incidence of any HAI (78% vs. 35%, p < 0.001). Eight VRE-positive patients (25%) developed VRE HAI compared with only 3 VRE-negative patients (1%) (p < 0.001). VRE screening had a 73% sensitivity, 93% specificity, 25% PPV, and 99% NPV for determining subsequent VRE HAI.

CONCLUSION

VRE colonization was present in 9% of SICU patients at admission. Negative VRE screen result had a high specificity and NPV for the development of subsequent VRE HAI. Empiric treatment of VRE infection may be unnecessary in VRE-negative patients.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III. Therapeutic study, level IV.

Vancomycin-resistant enterococci: Troublemaker of the 21st century

The emergence of multidrug-resistant and vancomycin-resistant enterococci during the last decade has made it difficult to treat nosocomial infections. Although various enterococcal species have been identified, only two (Enterococcus faecalis and Enterococcus faecium) are responsible for the majority of human infections. Vancomycin is an important therapeutic alternative against multidrug-resistant enterococci but is associated with a poor prognosis. Resistance to vancomycin dramatically reduces the therapeutic options for enterococcal infections. The bacterium develops resistance by modifying the C-terminal d-alanine of peptidoglycan to d-lactate, creating a d-Ala-d-Lac sequence that effectively reduces the affinity of vancomycin for the peptidoglycan by 1000-fold. Moreover, the resistance genes can be transferred from enterococci to Staphylococcus aureus, thereby posing a threat to patient safety and also a challenge for treating physicians. Judicious use of vancomycin and broad-spectrum antibiotics must be implemented, but strict infection control measures must also be followed to prevent nosocomial transmission of these organisms. Furthermore, improvements in clinical practice, rotation of antibiotics, herbal drugs, nanoantibiotics and the development of newer antibiotics based on a pharmacogenomic approach may prove helpful to overcome dreadful vancomycin-resistant enterococcal infections.

Effectiveness and cost of implementing an active surveillance screening policy for Acinetobacter baumannii: a Monte Carlo simulation model

BACKGROUND

Acinetobacter baumannii infections are common and associated with high mortality and costs. Early identification of asymptomatic carriers can reduce patient-to-patient transmission, but the sensitivity of A baumannii surveillance tools is poor, and thus active surveillance is not routine practice. This study examined whether an active surveillance screening policy can reduce the transmission, mortality, and costs associated with A baumannii.

METHODS

A simulation model was developed to determine the impact of active screening on patient outcomes. Model parameters included A baumannii prevalence, screening sensitivity and specificity, probability of transmission, progression from colonization to infection, mortality, and cost of screening, contact precautions, and infection. A scenario analysis was performed to evaluate the robustness of the results when varying the sensitivity of the screening test and the prevalence rate of A baumannii.

RESULTS

Assuming a screening sensitivity of 55%, active screening reduced A baumannii transmissions, infections, and deaths by 48%. As the screening sensitivity approached 90%, the reduction in transmissions, infections, and deaths reached 78%. For all scenarios tested, active surveillance was cost saving (19%-53% reduction in mean hospital cost per patient) except at a carrier prevalence of ≤2% and screening test sensitivity of ≤55%.

CONCLUSIONS

In institutions where A baumannii is endemic or during epidemics, implementing a surveillance program is cost-saving and can greatly reduce transmissions and deaths. Methodologies to improve the sensitivity of surveillance testing will help optimize the clinical impact of active screening programs on preventing the spread of A baumannii in health care facilities.

Control of the spread of vancomycin-resistant enterococci in hospitals: epidemiology and clinical relevance

BACKGROUND

The spread of vancomycin-resistant enterococci (VRE), particularly E. faecium, in hospitals leads to many cases of colonization, but only sporadic infections. Detailed and valid risk assessment is needed so that patients at risk can be protected from VRE infection. The principal aims of risk assessment must include not only lowering VRE-associated morbidity and mortality in patients at risk, but also refraining from unnecessary anti-infective measures among those who are not at risk.

METHODS

We selectively searched the PubMed database for pertinent articles on the epidemiology and clinical relevance of VRE in order to derive a uniform and practical hygiene strategy from the available scientific evidence.

RESULTS

Only low-level evidence is available for the interventions studied to date, and most of the recommendations that have been issued can be characterized as expert opinion. As a rule, VRE are not highly pathogenic; they tend to have high rates of colonization, but low rates of infection. The risk factors for colonization with VRE include (among others) the administration of antibiotics and immunosuppressants, prior hospitalization, diarrhea, intubation, and other invasive treatments. The areas of highest risk are hematology/oncology wards, liver transplantation wards, dialysis units, and neonatology wards.

CONCLUSION

The chain of infection can be broken by improved and consistently applied standard hygienic measures (hand and surface disinfection). Some patients are nonetheless at elevated risk of VRE infection. In specific clinical situations, the optimal protection of these patients against VRE infection demands the obligatory enforcement of stricter hygienic measures (contact isolation).

Significant reduction in vancomycin-resistant enterococcus colonization and bacteraemia after introduction of a bleach-based cleaning-disinfection programme

BACKGROUND

Vancomycin-resistant enterococcus (VRE) colonization and infection have increased at our hospital, despite adherence to standard VRE control guidelines.

AIM

We implemented a multi-modal, hospital-wide improvement programme including a bleach-based cleaning-disinfection programme ('Bleach-Clean'). VRE colonization, infection and environmental contamination were compared pre and post implementation.

METHODS

The programme included a new product (sodium hypochlorite 1000 ppm + detergent), standardized cleaning-disinfection practices, employment of cleaning supervisors, and modified protocols to rely on alcohol-based hand hygiene and sleeveless aprons instead of long-sleeved gowns and gloves. VRE was isolated using chromogenic agar and/or routine laboratory methods. Outcomes were assessed during the 6 months pre and 12 months post implementation, including proportions (per 100 patients screened) of VRE colonization in high-risk wards (HRWs: intensive care, liver transplant, renal, haematology/oncology); proportions of environmental contamination; and episodes of VRE bacteraemia throughout the entire hospital.

FINDINGS

Significant reductions in newly recognized VRE colonizations (208/1948 patients screened vs 324/4035, a 24.8% reduction, P = 0.001) and environmental contamination (66.4% reduction, P = 0.012) were observed, but the proportion of patients colonized on admission was stable. The total burden of inpatients with VRE in the HRWs also declined (median percentage of colonized inpatients per week, 19.4% vs 17.3%, P = 0.016). Hospital-wide VRE bacteraemia declined from 14/2935 patients investigated to 5/6194 (83.1% reduction; P < 0.001), but there was no change in vancomycin-susceptible enterococcal bacteraemia (P = 0.54).

CONCLUSION

The Bleach-Clean programme was associated with marked reductions in new VRE colonizations in high-risk patients, and VRE bacteraemia across the entire hospital. These findings have important implications for VRE control in endemic healthcare settings.