Transmission routes of the Zika virus

zikaThe Zika virus was first identified in Africa in the 1940s but has recently hit the headlines due to a sharp apparent increase in prevalence in some parts of the world, and a potential link with microcephaly.  The Zika virus is transmitted mainly through mosquito bites, but could there be any infection prevention and control implications? The short answer is no: human-to-human transmission of the Zika virus appears to be rare, although a small number of reports of sexual transmission, horizontal transmission (from mother to baby), and transmission via blood transfusions have been reported.
 
So, it seems that the steps required to prevent the transmission of Zika are similar to those required for malaria. Preventing being bitten by a mosquito in high prevalence areas is the key to prevention. What is not known is what is driving the recent increase in prevalence. But we will watch the emerging story carefully to ensure no other infection prevention and control challenges emerge.

Click on this link to show an interesting and insightful infographic about the Zika Virus: http://www.mphonline.org/zika-virus/  

 

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The physical environment and norovirus containment

noro
As norovirus season gets into full swing, spare a thought for those hospital that still have open plan ‘Nightingale’ style wards. These worked for Florence in a Victorian era, but narrow bed spacing and a lack of single rooms makes the containment of infectious diseases very challenging in these wards.
 
A study just published in the Journal of Infectious Diseases puts some numbers to this risk, finding that the frequency of norovirus outbreaks varied hugely across 6 hospitals in the London area. With 2 or fewer outbreaks reported in 5/6 and a whopping 16 separate outbreaks in one of the hospitals. This hospital had the lowest proportion of single rooms (a miserly 7%) and the tightest bed spacing (2.3m between bed centres), and the authors attribute these structural challenges to the frequent outbreaks in these hospitals.
 
Managing norovirus in these challenging ward environments may require some additional measures. Whilst effective hand and environmental hygiene are the key to controlling the spread of noro, this needs to be complemented with effective isolation of patients. Perhaps more segregated cohorting of patients would be a way to tackle segregation of patients with diarrhoea and vomiting in Nightingale wards? But the real solution to address this issue is to increase the number of single rooms in new hospitals!

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Shocking news about chlorhexidine

There is some evidence that passing electricity through a biocide enhances its biocidal activity – a so-called ‘bioelectric effect’. At the molecular level, biocidal activity depends on some sort of chemical interaction at a molecular level. Things tend to happen more quickly in chemical reactions when you add more energy – to a point. And it is likely to be the same with electricity added to a biocidal chemical reaction.
 
And so it is perhaps no surprise that a team of researchers from Belgium found that Porphyromonas gingivalis (an important organism in dentistry) biofilms were inactivated further by chlorhexidine when a 10mA current was run through them. The effect was not identified when a 1.5mA current was used, and the effect was actually fairly modest even with the 10mA current (87% vs 99% reduction, around a 1-log difference).
 
Assuming there is a measurable ‘bioelectric effect’ associated with chlorhexidine, how could this benefit be realised in practice? It’s perhaps possible to introduce a low electric current into specific points of the mouth during dental treatment, but the skin is a lot more tricky. Believe it or not, applying an electric current to the skin is used as a way to improve drug delivery, so perhaps the idea isn’t a far-fetched as it may seem!
 
Chlorhexidine is an excellent biocide, but its effectiveness is reduced by biofilms (as is the case for all biocides) and Gram-negative bacteria are relatively less susceptible to chlorhexidine than Gram-positive bacteria in laboratory studies. Electrifying the skin therefore, terrifying as it may sound, could be a way to help to address these challenges!

electric

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Evidence of source control for XDR Acinetobacter outbreak management grows

There is a steadily growing body of evidence that chlorhexidine washcloths can be effective in controlling multi-resistant Gram-negatives. Hot on the heels of a paper that demonstrated the effectiveness of the in controlling spread of Acinetobacter in a critical care unit1 comes a further paper relating to a hospital-wide outbreak of multi-resistant Acinetobacter. A new paper2 from Gray and colleagues from Montreal, Canada just published ‘in press’ in the Journal of Hospital Infection reported on the measures that they implemented to bring about control of the largest XDR Acinetobacter baumannii outbreak in the country to date. The outbreak, involving a single clonal strain, took place in multiple units of a large hospital, although transmission occurred on just two wards in the main. Interestingly, although carriage was detected at multiple sites on patients, only 57% were found to be rectal carriers.

Specific control measures included the creation of a cohort area on a ward with a strong culture of infection control and a patient population at lower risk of progressing from colonisation to infection. All affected wards underwent rigorous decontamination and additional training was provided to healthcare workers. XDR-Acinetobacter cases were provided with dedicated equipment and were bathed daily with 2% chlorhexidine gluconate-impregnated wipes as a source-control measure. Other general measures also included audits of compliance with hand hygiene and environmental decontamination, with feedback being given to staff.

Screening was in interesting aspect of this study. The fact that nearly half of patients were not rectal carriers contrasts markedly with CRE, for which rectal screening is considered sufficient to reliably detect carriage. This study highlights the need to sample a large number of body sites in order to exclude colonization with confidence.

In their discussion, the author express surprise that chlorhexidine bathing has been omitted as a control strategy in recent reviews, despite a number of papers that suggest that it is effective. Other work, including a study in a long-term facility has reported on the use of this strategy to control an Acinetobacter outbreak3. A 53% reduction in the incidence of Acinetobacter infection was reported in a long-term acute care facility following the introduction of chlorhexidine baths every other day for cases, and weekly for non-cases. The more intensive daily protocol used in this Canadian study may partially account for the greater success in controlling this outbreak.

1) Chung, Y. K., J. S. Kim, S. S. Lee, J. A. Lee, H. S. Kim, K. S. Shin, E. Y. Park, B. S. Kang, H. J. Lee and H. J. Kang (2015). “Effect of daily chlorhexidine bathing on acquisition of carbapenem-resistant Acinetobacter baumannii (CRAB) in the medical intensive care unit with CRAB endemicity.” Am J Infect Control 43(11): 1171-1177.

2) http://www.journalofhospitalinfection.com/article/S0195-6701%2816%2900005-0/abstract

3) http://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2009.179.1_MeetingAbstracts.A1427

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We need to improve standards of discharge disinfection to protect patients

01bd9ed4-4359-404c-a730-f4e93ac3c3a1 A key review article has been published in the Journal of Hospital Infection summarising the accumulating evidence that the status of the prior room occupant can influence the chances of the incoming occupant picking up an MDRO. The bottom line is that if you are admitted to a room previously occupied by a patient with an MDRO (including MRSA, VRE, C. difficile and Acinetobacter sp.), you are twice as likely to acquire that MDRO. The impact of these findings is clear: we need to improve standards of discharge disinfection to protect the incoming occupant. So how can we do this? There are several paths to follow towards the same end – and these are not mutually exclusive:

Improve the cleaning / disinfection process
The advent of fluorescent markers and other similar approaches has provided the tools for us to “demystify” the cleaning / disinfection process, and provide hard evidence as to whether or not surfaces are being cleaned. ‘Performance managing’ this process can result in impressive improvements (although data are awaited eagerly on improved patient outcomes).

Developing new modalities to make cleaning / disinfection easier
The emergence of disinfectant wipes solves a number of important challenges to cleaning and disinfection: correct formulation, no risk of contaminating a cleaning solution, and – perhaps most importantly – convenience.

Producing novel disinfectants
As our understanding of the importance of biofilms on hospital surfaces evolves, the need for disinfectants formulated specifically with anti-biofilm activity in mind is clear. Gama is working towards this end through a partnership with Cardiff University.

Improved design
Poorly designed hospital surfaces that are difficult (or impossible!) to clean can be addressed through improved design (check out Gama’s easy-clean commodes and keyboards).

Reduced patient shedding
One way to reduce the level of environmental contamination is to control the shedding of MDROs from patients through regular chlorhexidine bathing. This has been shown to reduce the level of skin and environmental contamination, and improve patient outcomes.

Antimicrobial surfaces
An attractive approach is to somehow make surfaces antimicrobial to continuously reduce the levels of contamination. There are various options to achieve a similar aim, and some evidence that patient outcomes may be improved.

Automated room decontamination (ARD)
ARD systems reduce or remove reliance on the operator to assure adequate distribution and contact time of the active agent. There is accumulating evidence that these systems (both HPV and UV) protect incoming occupants from the increased risk from the prior room occupant. In high risk settings, it is becoming increasingly clear that these systems will become the standard of care in coming years.

It is difficult to know which of the above approaches to prioritise since comparative data on the relative impact of these methods is almost non-existent. But we need to find a way to improve the standards of discharge disinfection one way or another!

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