Barriers to genetic manipulation of Enterococci: Current Approaches and Future Directions

Enterococcus faecalis and Enterococcus faecium are Gram-positive commensal gut bacteria that can also cause fatal infections. To study clinically relevant multi-drug resistant E. faecalis and E. faecium strains, methods are needed to overcome physical (thick cell wall) and enzymatic barriers that limit the transfer of foreign DNA and thus prevent facile genetic manipulation. Enzymatic barriers to DNA uptake identified in E. faecalis and E. faecium include type I, II and IV restriction modification systems and CRISPR-Cas. This review examines E. faecalis and E. faecium DNA defence systems and the methods with potential to overcome these barriers. DNA defence system bypass will allow the application of innovative genetic techniques to expedite molecular-level understanding of these important, but somewhat neglected, pathogens.

Increasing tolerance of hospital Enterococcus faecium to handwash alcohols

Alcohol-based disinfectants and particularly hand rubs are a key way to control hospital infections worldwide. Such disinfectants restrict transmission of pathogens, such as multidrug-resistant Staphylococcus aureus and Enterococcus faecium Despite this success, health care infections caused by E. faecium are increasing. We tested alcohol tolerance of 139 hospital isolates of E. faecium obtained between 1997 and 2015 and found that E. faecium isolates after 2010 were 10-fold more tolerant to killing by alcohol than were older isolates. Using a mouse gut colonization model of E. faecium transmission, we showed that alcohol-tolerant E. faecium resisted standard 70% isopropanol surface disinfection, resulting in greater mouse gut colonization compared to alcohol-sensitive E. faecium We next looked for bacterial genomic signatures of adaptation. Alcohol-tolerant E. faecium accumulated mutations in genes involved in carbohydrate uptake and metabolism. Mutagenesis confirmed the roles of these genes in the tolerance of E. faecium to isopropanol. These findings suggest that bacterial adaptation is complicating infection control recommendations, necessitating additional procedures to prevent E. faecium from spreading in hospital settings.

Isopropanol at 60% and at 70% are effective against 'isopropanol-tolerant' Enterococcus faecium

The bactericidal activity of isopropanol was determined against Enterococcus faecium ATCC 6057, ST 796 (isopropanol-tolerant strain) and Enterococcus hirae ATCC 10541 (EN 13727). Isopropanol at 60% and 70% were effective (≥5.38 log₁₀-reduction) in 15 s against all strains but 23% isopropanol was not (<0.99 log₁₀-reduction in ≤15 min). Isopropanol at 70% was tested against E. faecium in the four-field test. Eight millilitres was not effective enough in 1 min (<5 log₁₀-reduction), whilst 16 mL was effective (≥5.85 log₁₀-reduction). Healthcare workers can be reassured that 60% and 70% isopropanol with an appropriate volume are effective against E. faecium.

Implementing an electronic hand hygiene monitoring system: Lessons learned from community hospitals

BACKGROUND

Measuring and providing feedback about hand hygiene (HH) compliance is a complicated process. Electronic HH monitoring systems have been proposed as a possible solution; however, there is little information available about how to successfully implement and maintain these systems for maximum benefit in community hospitals.

METHODS

An electronic HH monitoring system was implemented in 3 community hospitals by teams at each facility with support from the system vendor. Compliance rates were measured by the electronic monitoring system. The implementation challenges, solutions, and drivers of success were monitored within each facility.

RESULTS

The electronic HH monitoring systems tracked on average more than 220,000 compliant HH events per facility per month, with an average monthly compliance rate >85%. The sharing of best practices between facilities was valuable in addressing challenges encountered during implementation and maintaining a high rate of use.

DISCUSSION

Drivers of success included a collaborative environment, leadership commitment, using data to drive improvement, consistent and constant messaging, staff empowerment, and patient involvement.

CONCLUSIONS

Realizing the full benefit of investments in electronic HH monitoring systems requires careful consideration of implementation strategies, planning for ongoing support and maintenance, and presenting data in a meaningful way to empower and inspire staff.

Back to basics: hand hygiene and isolation

Purpose of review

Hand hygiene and isolation are basic, but very effective, means of preventing the spread of pathogens in healthcare. Although the principle may be straightforward, this review highlights some of the controversies regarding the implementation and efficacy of these interventions.

Recent findings

Hand hygiene compliance is an accepted measure of quality and safety in many countries. The evidence for the efficacy of hand hygiene in directly reducing rates of hospital-acquired infections has strengthened in recent years, particularly in terms of reduced rates of staphylococcal sepsis. Defining the key components of effective implementation strategies and the ideal method(s) of assessing hand hygiene compliance are dependent on a range of factors associated with the healthcare system. Although patient isolation continues to be an important strategy, particularly in outbreaks, it also has some limitations and can be associated with negative effects. Recent detailed molecular epidemiology studies of key healthcare-acquired pathogens have questioned the true efficacy of isolation, alone as an effective method for the routine prevention of disease transmission.

Summary

Hand hygiene and isolation are key components of basic infection control. Recent insights into the benefits, limitations and even adverse effects of these interventions are important for their optimal implementation.

Endophthalmitis following intravitreal anti-vascular endothelial growth factor (VEGF) injection: a comprehensive review

The purpose of this review is to report and summarize previously reported studies and assess many of the individual steps of the intravitreal injection procedure's possible effect on the prevention of endophthalmitis. The pooled endophthalmitis rate from 20 large retrospective case series of anti-VEGF injections was 144/510,396 (0.028%; 1/3,544). Injections may be performed in an office-based location or in an operating room (OR) and low rates of endophthalmitis can be achieved in either location with careful attention to asepsis. Pre- or post-injection topical antibiotics have not been shown to be effective, and could select for more virulent microorganisms. Povidone-iodine prior to injection is accepted as the gold-standard antiseptic agent, but aqueous chlorhexidine may be an alternative. Antisepsis before and after gel or subconjunctival anesthetic is suggested. The preponderance of Streptococcal infections after intravitreal injection is discussed, including the possible role of aerosolization, which can be minimized by using face masks or maintaining silence. As with other invasive procedures in medicine, the use of sterile gloves, following adequate hand antisepsis, may be considered. Control of the eyelashes and lid margin is required to avoid contamination of the needle, but this can be achieved with or without a speculum. Techniques to minimize vitreous reflux have not been shown to reduce the risk of endophthalmitis. Same day bilateral injections should be performed as two separate procedures, preferably using drug from different lots, especially when using compounded drugs.

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.