LL Part 2: An 'Association'

Does a doctor identifying an 'association' between deaths and a nurse, mean the nurse is culpable?

Following on from the previous post (here)

Before I continue down the journey of pathogens in hospital waste water (HWW), I want to pause and have you, the reader, consider a question:

Does a doctor identifying an association between deaths in a hospital ward and a nurse, mean that nurse is culpable?

Let’s consider the following example in which two nurses became ‘associated’ with a cluster of deaths in an Oklahoma NICU. If those two nurses had worked at the CoCH, no doubt at this point police would have been called, arrests made, and we would have watched their trials unfold in the headlines like a national sport. Instead, and I am certain they are both thankful for this, cooler heads prevailed.

Deaths in a Neonatal Ward

During 1997 in the NICU of an Oklahoma State childrens’ hospital a cluster of eleven (11) neonates died of initially unexplained circumstances. Surely, each one had a cause of death on their death certificate, but the true underlying cause was yet to be identified.

Hospital clinicians and management eventually recognised that the neonates were a cluster, and that the cluster of deaths meant something wasn’t right. By March 1998 they devised and implemented an intervention. It was decided there had been an outbreak.

Epidemiologists were called in and a retrospective study (an investigation looking back over the medical records and laboratory samples from the preceding 15 months) was conducted seeking to describe the outbreak and determine how many neonates had become infected, the case-fatality rate and, if possible, the source of and risk factors for infection.

The epidemiologists resolved that each infant had become infected via bloodstream infection or endotracheal tube (ETT) colonisation by a pathogen called Pseudomonas aeruginosa (while we normally would use the P.aeruginosa in scientific and academic texts, for simplicity’s sake I will use Pseudomonas here). Review of medical records identified more cases of Pseudomonas infection, 46 in total, and even more deaths, 16 in total, had occured in the NICU between January 1997 and March 1998. This meant the case fatality rate was 34.8% (16/46). Infants with low birthweights (<1000g or, as the ‘in vogue’ journalists in the Lucy Letby trial have said ad nauseam - those that ‘weigh less than a bag of sugar’) were significantly more likely to both become infected and succumb to Pseudomonas infection than those with higher birthweights (>1000g). Further, those with Pseudomonas infection were far more likely to die than those neonates who passed through the NICU and did not become infected (i.e.: 34.8% of Pseudomonas-infected neonates died while only 5.3% of uninfected neonates died). Finally, and perhaps worst of all, 80% of neonates found to have had a bloodstream infection - also known clinically as bacteraemia or sepsis, died.

A bloodstream infection most often occurs when the pathogen has been allowed to colonise some part of the hospital or equipment, and either the baby, or the hands of the nurse caring for the baby, comes into contact with the pathogen and transfers it to the baby’s skin. Given that neonates are often catheterised (that is, a tube is inserted into a vein or into vessels in the umbilical stump to deliver medication directly into the blood), the pathogen is able to hijack along these breaks in the baby’s skin and directly access the bloodstream. The epidemiologist’s findings meant that bloodstream infection with Pseudomonas was a death sentence for most of the already poorly neonates.

But this is where we take an interesting turn.

During the course of their investigation, and like the Lucy Letby trial, two nurses became ‘associated’ with the cluster of deaths. But as I said in the introduction, rather than calling the police the epidemiologists sought to understand how and why those nurses were associated. Staff were interviewed, laboratory tests were conducted, and intelligent conclusions were drawn.

More than 100 doctors and nurses that accessed the NICU, were swabbed and tested, and only three nurses returned positive swabs for Pseudomonas. Two of these nurses were the two that were most ‘associated’ with the infected and deceased neonates. The third had no significant association with most of the case patients.

The drains in two hand basins in the hospital had also tested positive.

While not every case patient had interacted with the two ‘associated’ nurses, case patients were found statistically to be more likely to have had interactions with them than not. Across a subset of 28 case patients, the first nurse had interacted with 20, and the second had interacted with 16. The key risk factors identified during this analysis that were linked to infection included the number of days on a ventilator (the longer the neonate had breathing assistance increased their risk of succumbing to infection) and the number of hours they were exposed to these nurses.

Why these two nurses?

At this point you may be wondering what was special or different about these two nurses that resulted in their being ‘associated’ with the cluster of deaths. The short answer is… Their fingernails.

Both nurses had long fingernails. One had naturally long fingernails while the other regularly had manicures at the nail salon during which false nails (gels) were installed. While both used a nail polish, tests showed the nail polish they both wore at the time was not to blame. However, it was available to infer that the long nails had allowed Pseudomonas to colonise the hands of both nurses and potentially acted as a transport mechanism.

However, this is also where the cooler heads prevailed. Rather than withdrawing both from their employment, calling the police and initiating headlines about how two neonatal nurses caused sixteen deaths - the epidemiologists made one final finding.

They found the evidence they had collected did not identify the mechanism for how the nurse’s fingernails had become colonised, that they could not say for certain whether these two nurses’ handwashing practices differed from that of any other member of the clinical staff, nor whether colonisation of these nurse’s hands was the cause of, or caused by, the outbreak.

What does it mean to be culpable?

In UK criminal law, murder is defined as the intentional killing of another person with malice aforethought. Malice aforethought refers specifically to the intention or desire to cause serious harm or death to another person. Malice aforethought is often described in textbooks as mens rea - the mental mind to commit the act that brings about the murder, which is known as the actus reas. In laymans terms there are three necessary elements in order for you to be guilty of murder: you (1) must be of sound mind, (2) must have killed another human, and (3) must have intended to cause death or grievous bodily harm. The third element can also be made out where the person, absent an intention to caused death, does so through wrongful conduct and is found to be recklessly indifferent as to the risk of causing death or grievous bodily harm (wicked recklessness).

Alternatively, manslaughter can be commited in one of three ways:

1. Killing with the intent for murder but where a partial defence applies, namely loss of control, diminished responsibility or killing pursuant to a suicide pact,

2. Conduct that was grossly negligent given the risk of death, and did kill ("gross negligence manslaughter"); and,

3. Conduct taking the form of an unlawful act involving a danger of some harm that resulted in death ("unlawful and dangerous act manslaughter").

While the first is referred to commonly as voluntary manslaughter, the latter two are often described as involuntary manslaughter.

Culpable homicide is another term often used - and is the equivalent charge to manslaughter in Scottish Law. It may be found where the accused was responsible for their actions and caused death through wrongful conduct, but there was no intent and no wicked recklessness.

Any prosecution of the two nurses in the Oklahoma example above for either charge would have needed to represent their involvement as either murder (acts or omissions of acts with intent or reckless indifference) or manslaughter (acts or omissions of acts with intent but diminished capacity - an insanity defence, or gross negligence). They would have to have painted both nurses as evil monsters and come up with a range of circumstantial testimony to support the ‘association’ and hindsight claims from other staff that often start from the statement: “Those two just weren’t right, you know?”

Sound familiar?

Stay tuned…

The next post in this series can be found here.

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Further reading:

(1) https://www.nytimes.com/2000/03/24/us/study-links-bacteria-long-nails-and-baby-deaths.html

(2) https://pubmed.ncbi.nlm.nih.gov/10697282/