Look out: antiseptic resistance genes about!


A Turkish study has found a surprisingly high rate of antiseptic resistance gene carriage in clinical isolates of staphylococci (71% of 69 isolates carried either qacA/B or smr, which have been associated with reduced susceptibility to chlorhexidine). This study highlights the potential for bacteria to eventually develop reduced susceptibility or resistance to whatever is thrown their way!

The study team searched for various antiseptic resistance genes in a collection of 69 Staphylococcus species isolates (a mixture of MRSA, MSSA, and methicillin-resistant and – susceptible coagulase-negative staphylococci (CoNS)) and 69 Enterococcus species. More than 50% of the S. aureus isolates and 85% of the CoNS isolates harboured one or other gene that has been linked with antiseptic resistance (various qac genes, and smr). Furthermore, laboratory testing showed that isolates carrying the resistance genes exhibited lower levels of susceptibility to chlorhexidine, which has been reported elsewhere. The situation was different in Enterococcus species, where none were found to carry these antiseptic resistance genes. However, laboratory testing did show that vancomycin-resistant enterococci (VRE) were less susceptible to antiseptics than vancomycin-susceptible enterococci. This suggest that there may be some link between the mechanism of reduced susceptibility to vancomycin and chlorohexidine, which makes sense because changes in cell wall synthesis are essential to both.

As in other studies, the level of reduced antiseptic susceptibility identified in the laboratory in this study was orders of magnitude lower than the in-use concentration of chlorhexidine that is applied to patients skin. However, it does suggest that, over time, reduced susceptibility to chlorhexidine is likely to become more of a clinical challenge.


Chlorhexidine daily bathing reduces MDRO colonisation

There is accumulating evidence that daily bathing using chlorhexidine wipes prevents the transmission of MDROs. Most of the evidence to date has been about reducing Gram-positive bacterial pathogens (such as MRSA and VRE). So a study including Gram-negative bacterial pathogens (such as Klebsiella pneumoniae and E. coli) is welcome! A recent Spanish study shows that daily bathing with chlorhexidine is effective in reducing colonisation with MDROs.

The prospective intervention study was performed in a 24 bed mixed-speciality ICU in a Spanish hospital over two years. Daily bathing using Clinell Wash Cloths (2% chlorhexidine gluconate, CHG) was implemented after 11 months, to provide 12 months pre, and 11 months post intervention data. Mechanically ventilated patients and patients known to be colonised with MDROs were bathed daily using CHG. Patients admitted from other hospital wards or transferred from other hospitals were screened for MDROs on admission, and all patients were screened once per week for MDROs (or twice per week for mechanically ventilated patients).

Around 25% of patients admitted to the unit during the intervention were bathed daily using CHG. The key finding is the stark change in the incidence of colonisation with MDROs associated with the introduction of CHG (see Figure below). Importantly, there was no significant change in antimicrobial consumption on the ICU during this period. Interestingly, the authors report that no significant reduction in the incidence of MDRO colonisation was found in a surgical ICU during the same period that was not using CHG bathing, which provides a useful ‘natural’ control group for these findings. Whilst there was no significant reduction in infections in total or due to MDROs, the study was not powered adequately to detect a reduction in these outcomes. It’s a fairly safe assumption that if you reduce the number of patients who are colonised with MDROs, this will have a knock-on effect of reducing the number of infections with MDROs!

The study setting had a high prevalence of MDRO colonisation, with approximately 20% of patients colonised with one MDRO or another. Whilst this is a single centre study performed over a relatively short period of time, it provides further evidence that daily CHG bathing reduces the transmission of MDROs including antibiotic-resistant Gram-negative bacteria.



RediRoom Mk II: Infection Prevention and Control evaluation

Following on from last week’s blog about the functional characteristics
of the RediRoom (a temporary isolation room designed for single patient use), this week’s blog reviews a second study that evaluates the infection prevention and control characteristics and potential benefits of the RediRoom.

Whether to favour single rooms or multi-occupany bays is a balance. On the one hand, single rooms provide more privacy, less noise, and better containment of pathogens. On the other hand though, multi-occupancy bays provide more social interaction, reduced cost in terms of staffing levels, and patients who fall or deteriorate will be spotted more quickly. Perhaps as a result of this balancing act, patient opinion is divided on whether single rooms or mutli-occupancy bays are better. Most modern hospitals have decided to provide a mixture of single rooms and multi-occupancy bays, to offer flexibility to staff in finding the best accommodation for patients. The RediRoom occupies the middle ground: providing many of the benefits of single occupancy rooms (in terms of more privacy, less noise, and better containment of pathogens) and multi-occupancy bays (patient visibility, and reduced cost in terms of staffing).

The RediRoom was installed in a simulated clinical environment, and its function was assessed from an IPC viewpoint against key standards or guidelines (Australasian Health Facility Guidelines and the Department of Health (NHS) Infection Control in the Built Environment), and the ease of assembly and dismantling, and the ability to clean the RediRoom as judged by the removal of fluorescent markers were evaluated. The RediRoom was found to be fully compliant with 17/19 relevant guidelines or standards, and partially compliant with the other two. The two guidelines rated as partially compliant were the storage and use of personal protective equipment, and the provision of additional storage capacity. Another limitation was the lack of a sink for hand hygiene inside the RediRoom, but there is provision for alcohol gel to be situated both inside and outside the RediRoom. The review of assembly and dismantling of the RediRoom identified limited infection control risk. Impressively, the RediRoom was installed in less than 5 minutes! Finally, the cleaning assessment found that the UV fluorescent markers were fully removed from 23 (96%) of the 24 surfaces marked, and partially removed from the other surface. Whilst this cleaning assessment was not performed in the business of clinical practice, it demonstrates that the RediRoom does not present a barrier to cleaning in principle.

The RediRoom performed well when compared against standards and guidelines for a safe healthcare environment, it did not introduce infection control risks during assembly and dismantling, and was designed in a way that should not be a barrier to cleaning. Clearly, further assessments of the RediRoom in clinical practice are required, but it is poised to deliver IPC benefits!


RediRoom put through its paces


An Australian study has evaluated various functional characteristics of the RediRoom, a temporary isolation room designed for single patient use. The mixed methods approach involved video recording, interviews, and objective temperature and humidity measurements within a crossover intervention study, concluding that the RediRoom had similar functional performance to performing patient care in an open plan area.

Single rooms are in short supply in many parts of the world, especially in the NHS. The RediRoom provides a temporary single room that can be used for contact or droplet isolation of patients. It is designed to be used to provide additional isolation capacity for individual patients in inpatient hospital settings, and also to provide temporary single rooms for patient triage in emergency situations.

In this study, the RediRoom was evaluated in a simulated clinical ward environment. Participants undertook a range of clinical nursing activities in the RediRoom or in a control area, including transferring patients, administration of medications, measurement of observations, performing an aseptic technique, bed bathing a patient, and cardiopulmonary resuscitation. A network analysis of staff movements in the room, and staff feedback via interviews and a questionnaire were used to evaluate the functionality of the RediRoom vs. control area. Also, temperature and humidity was measured in the RediRoom and control area.

The time taken and the number of movement required to complete the clinical nursing activities was broadly similar in the RediRoom and control area. A network analysis of the two activities that involved the most individual movements showed that there was close similarity in the pattern of movements in the RediRoom and control area. Recurring themes from interviews with staff were a sense of restriction, temperature, and management of critically ill patients. However, it is important to note that the RediRoom was not compared against another single room, but against an open plan area. It is likely that the sense of restriction and temperature themes would be less prominent if the RediRoom was compared to an isolation room. There was a slight increase in temperature in the RediRoom compared with the control room, of around 0.5°C.

Overall, the RediRoom had similar functional performance to performing patient care in an open plan area. The study focussed entirely on any impact that the RediRoom would have on functional performance of clinical nursing tasks, and did not quantify the main benefit of the RediRoom, in terms of reducing infection prevention and control risk, which is another story altogether…


Self-disinfecting surfaces: promising but not there yet


A recent JHI study highlights both the promise and limitations of self-disinfecting surfaces. The study evaluated the efficacy of five different self-disinfecting surfaces against S. aureus under simulated real-life conditions. The small antimicrobial effects noted initially disappeared once most of the surfaces began being cleaned using alcohol wipes!

The team examined the efficacy of five self-disinfecting surfaces: a micro-patterned film (based on Shark skin to reduce bacterial adhesion), and four surfaces dosed with antimicrobial agents: zinc molybdenum (ZM), polyguanidin silica (PS) and two based on membrane-active polycations (maPK-I and maPK-a). A bacterial load of 8-log cfu was applied and then dried, before being sampled at 15 mins and 3 hours using contact plates. Only the MP, maPK-I and maPK-a based surfaces resulted in a reduction in bacterial contamination. The antimicrobial impact of MP and maPK-i disappeared after a single disinfection cycle, so were not stable enough to be useful. However, the maPK-a surfaces continued to exhibit an antimicrobial impact but only up to 19 disinfection cycles.

The inoculum used in the study was rather high (at 8-log), and probably not representative of the real-life environment, where contamination levels are usually lower. Also, the first exposure point tested was 15 minutes, whereas more rapid activity would be a favourable characteristic for a self-disinfecting surface: after all, how long does it take for a transmission to occur? Finally, the study only included S. aureus and, importantly, did not include C. difficile spores; sporicidal activity would be a huge plus for a candidate self-disinfecting surface.

The study used copper alloy surfaces as a control group, and based on these results, copper surfaces remain the prime candidate for antimicrobial surfaces. However, installing copper alloy surfaces is expensive, not suitable for all surfaces / equipment, and may not be durable in the clinical environment. Therefore, further development is required to achieve a low cost, high efficacy, durable self-disinfecting surface suitable for use in the clinical environment.



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