This week’s blog is the ninth in a series by Dr Evonne T Curran (@EvonneTCurran).
When you find out you have made a whopper of a mistake, (or like me, the whopper of a mistake was to follow others who made the original whopper of a mistake), there are choices. The wrong decision is to double-down and deny the existence of any mistake. This position is challenging as the evidence will eventually drown the pretence of the absence of error. Its far better to admit the error and then find out how it happened. However, if you want to be ‘highly reliable’ you could also consider investigating whether the process which resulted in the whopping mistake, in this case the mode of respiratory transmission, is also present for contact transmission. This blog is an exploration of hand contact transmission – and guess what – it’s a pea souper…
Declaration: I have a motive. I want the mode of respiratory transmission changed to reflect the evidence that COVID is airborne and that healthcare workers (HCWs) were and are ill-protected with leaky surgical masks for airborne infections. My hope is that if I present evidence on numerous other errors in our understanding of transmission the drawing board will be called for and we can start again.
I will start with a bold statement: There is an absence of evidence to support hand hygiene being the single most important means to prevent hospital acquired infections (HAI). Even though the World Health Organization says it is… In this publication from 2022, the WHO stated that:
“Whether implemented as a stand-alone intervention or integrated into multifaceted interventions, hand hygiene as been high-lighted as the most effective single measure to reduce the transmission of micro-organisms/pathogens and infection in health care settings (38,39).”
The above statement is also bold, assertive, but without supporting evidence. References 38 & 39 (please check this out) neither mention hands nor hand hygiene. I have been on the hunt for several years and despite similar statements being repeated by the WHO, and other eminent authors in high-impact journals, the references behind such statements omit supporting evidence. Let’s examine some common HAI…
Is hand hygiene the number 1 way to prevent vascular access device-related Infections?
No. The number 1 way to prevent vascular access device-related infections is to remove devices as soon as clinically indicated. Hand hygiene cannot remove the micro-organisms present on the patient’s skin which if you leave the device in long enough will eventually cause infection. (Hand Hygiene remains vital – but its catheter removal or catheter avoidance that is number 1 for prevention).
Is hand hygiene the number 1 way to prevent ventilator associated pneumonia (VAP)?
No. Hand hygiene does not make it onto the VAP prevention bundle. Prevention is about sedation, weaning and patient position.
Is hand hygiene the number 1 way to prevent surgical site infections (SSI)?
No. Its difficult to pick a number 1, but I would suggest it’s a combination of sterile instruments, sterile clothing / surfaces, theatre air quality and hand hygiene. This will stop organisms shed from the patient, and the surgical team, entering on the open sterile surgical site to facilitate infection. (The surgical scrub is important – but not No 1).
Is hand hygiene the number 1 way to prevent Clostridioides difficile (C.diff) infections?
No. Going to let you into a secret here – the best way to prevent C. diff spreading in hospitals is to stop the need for antibiotics and the best way to stop that need, is to prevent HAI. However, according to the NHS web site, “when someone has a C. diff infection, it can spread to other people very easily if the bacteria found in the person’s poo gets onto objects and surfaces.” There is a bit missing here. If the bacterium is on objects and surfaces it is not inside people and cannot (yet) infect them. So how does it get into someone else’s gut to cross-infect them? It must be ingested. Hands of both the patient and HCW as always, are in the dock – but we lack evidence. We must also note the bacterium and its spores get in the air when we flush a toilet. Thus, although weakly acknowledged, airborne transmission has also been put in the dock. But how much gets in via air – to mouth – to ingestion, or patient hand – to own mouth – to ingestion, or HCW-hand – to patient’s mouth – to ingestion, or object – to mouth – to ingestion, is itself up in the air. [Our knowledge on the exact ways in to infect is poor].
What does this mean?
IPC has been hindered by becoming overly focused on one problem – HCW hand-related transmission. The time for a reassessment of all transmission is long overdue. The evidence is poor. One Cochrane review found that multimodal interventions that contain all WHO recommended strategies may slightly improve hand hygiene compliance. It was unclear whether this intervention reduced infection. The IPC world still utilises the WHO 2009 hand hygiene guideline. Chapter 7.5 is the cross-transmission of organisms from contaminated HCW hands. The section begins with a statement.
“Cross-transmission of organisms occurs through contaminated hands. Factors that influence the transfer of microorganisms from surface-to-surface and affect cross-contamination rates are type of organism, source and destination surfaces, moisture level, and size of inoculum.”
Thirteen references support the statement. There is a clear omission which manifests when you review the references. Of the 13 references, 2 were useful mechanistic experiments which showed that hands did transfer pathogens. However, of the remaining 11 outbreak citations, 6 involved a HCW with damaged skin (2 HCWs with Onychomycosis, 1 with dermatitis, 1 with psoriasis,1 intermittent otitis externa and 1 surgeon with hand colonisation). Inexplicable then that WHO failed to list damaged/infected skin as a ‘factor of influence’. One outbreak was attributed to a contaminated false nail. The remaining 5 involved a contaminated liquid soap dispenser, 1 unsafe injection practices (multi-dose vials), 1 open suctioning ‘aerosolising’ followed (of course) by poor hand hygiene. Lastly, one demonstrates evidence of hand transmission with a fungus brought in from home involving contaminated hand cream and pet dogs. The point being that once we remove the HCWs with skin conditions, there isn’t much left.
Blaming HCW hands is akin to applying a satisfaction of search bias. People find a plausible cause – and stop looking. However, this paper presents the case for the airborne dispersal of pathogens from HCWs involved in outbreaks – Cloud HCWs. In outbreak investigations it was shown that HCWs some with small lesions (others just colonised) disseminated via the air sufficient pathogen for the term ‘cloud HCW’ to be coined. Thus, we also need to consider what Cloud Patients (e.g., patients with wound infections), or Cloud Procedures (bed-making, cleaning floors, dressing changes) contribute to this. We just don’t know how much transmission is attributable to hands and how much to airborne dissemination. We do precious little to prevent airborne dissemination – as has been evidenced in this pandemic. So, in summary we have both the mode of respiratory transmission and contact transmission – wrong. Again, this does not mean hand hygiene is not important but there must be balance and we need evidence of the contribution from each mode.
Scientists consider air as a fluid. This is useful as it means we can consider our clinical areas abide in what is akin to a continuously moving pathogen pea soup. When we consider the air as a contaminated liquid – we become aware of what the air can disseminate and how we contribute to pathogen dissemination – by actions and omissions. That key nosocomial pathogens are disseminated via the air must be considered settled science. Just as hands spreading pathogens is also settled science. What we don’t know is how much transmission arises from either mode. The pea soup pathogen thickness (hazard) will be different in different settings.
Back to I’ve never liked hand hygiene day. It’s not because I don’t believe hand hygiene is important, it is important – but we only have ‘opinion’ that it’s the number 1. Thus, as evidence exists that it is not number 1 for many HAI categories, we downplay the real most important infection prevention actions. Also, I can find no evidence of a return of investment for either hand hygiene days or for mandatory hand hygiene audits.
What can we say with confidence about hand hygiene?
- It’s not the number 1 way to prevent any category of infection, but it is essential to all HAI prevention.
- Regarding transmission prevention – the jury is out – we don’t know the extent to which transmission happens via the pathogen pea soup (air) or via contact with hands [or equipment not considered here], but we do know that airborne dissemination and airborne infections – like SARS-CoV-2 – need preventing by indoor air quality and, for airborne infections, respiratory protection.
Anyone for an IPC drawing board…
NB for the sake of space only, this blog did not consider the transmission of indirect contact from surfaces….