Plasmids and antibiotic resistance

#KYJ -  Superbugs, Plasmids and Genetic mutation.

Make a note of " MCR-1 ".

It is a buzz term that you will hear more about.  We start our explanation of this, with a  a basic review of microbiology.... 

Hello.... Hello??  Are you still awake?  Stay with me.

Bacteria a living cells with cell walls made of carbohydrates (cellulose- a complex sugar).

Some have a fatty (lipid) membrane coating around the cell wall. 

Inside, are most of the goodies that other cells have, organelles like mitochondria, cytoplasm, lysosomes, and nucleus to name a small familiar sample.

Inside the nerve centre of the bacteria is genetic material (genes) arranged in to long protein strands called chromosomes.  This is where the bacteria gets its instruction to function and reproduce.  

Unlike animals and plants that must mate with a male/female combination to reproduce, bacteria are asexual; boring I know, but true none the less.  To divide into two identical copies of its self (producing offspring called Daughter cells), bacteria copies its chromosomes, then simply splits down the middle to form two new cells. 2 become 4 become 8 become 16 and so on ( look up you year 8 maths books , or have a chat to any Amway dealer to see how effective the power of duplication becomes.)

Anyhow I digress... 

Given that bacteria make absolute clones of them self, you would think they can't change.   But we know they do.   They become resilient, and adapt to new environments.  They mutate.

Enter the plasmid.

A plasmid is a rogue speck of genetic material that lives in the cytoplasm (watery juice) of the bacteria.  Plasmids are genetic coded proteins that can become altered when a bacteria is exposed to an antibiotic (that should have killed it) but survives.   Plasmids change, replicate on their own and translocate genetic information with genes inside the nucleus.

Now this surviving bacteria passes on this information to its daughter cells creating a bacteria that is now resistant to the antibiotic that previously would have killed its grand parents.

Are you still awake? 

Ok.  So plasmids don't just mutate and affect the host bacteria, but they can also share genetic information to other bacteria, even other species of bacteria.  A Strep can share its resistance recipe with a Staph, or an E.coli with an Enterococci, or a Bacillus with a diplococcus.

Frightened yet?

Recently, an E.coli strain was discovered in a urine sample of an American woman with a UTI.  This infection is resistant to every antibiotic.  EVERY ANTIBIOTIC.   

This drug resistant E.coli strain has a gene called MCR-1 which is harboured in the E.coli's plasmid.  

This E. coli bacteria with the mcr-1 gene could pass its plasmid and gene  to another superbug with other mutations-- creating a truly super-superbug that resists all known antibiotics.

The bio surveillance role that nurses and doctors have was always important, but this is going to have implications on infection control practices going forward.  

I'm off to wash my hands ... again! 

Adenosine

#KYJ.  Adenosine.
Have you ever given this IV drug to a patient?
It is used to cause a complete block through the AV node, in patients experiencing a Junctional Tachycardia (previously and more commonly called Supraventricular Tachycardia (SVT)).

Its use is common, and when given correctly it is very effective.  In the past you may have been taught to give it as a neat push IV.  But more recently it has become popular to dilute the required dose up to a 20ml volume and rapidly push in a largish (18g) IV cannula in the antecubital fossa, and quickly flush with a 10-20 ml saline

This drug has the effect of stopping the heart.  Thankfully it has a very short half life of 4-7 seconds (requiring the rapid push). Like a computer that is playing up, you get the sense that this drug is like a cardiac "Reset button", like someone said "have you tried turning it off, then on again?"

Vials come in 6 mg but it is very common (almost expected) that we start at 9mg.
A common regimen is
3 x 2 minutely doses starting at
9mg - 9mg - 12 mg.

If it works on dose 1, the other two are not needed.

Doses are expected to work in 5-10 seconds so as you give the push, the patient needs to be attached to the cardiac monitor.  You are watching for the SVT to deteriorate into a severe bradycardia or asystole (flat line).

Their heart stops.... Then in 3-5 seconds it automatically restarts, hopefully into a normal sinus rhythm .... It's a reset button.

Patients often experience fear, and altered consciousness as their brain oxygenation ceases for that few seconds.  Many describe a sense of doom, or near death phenomenon like a Tunnel of light, out of body experiences or a peaceful place of comfort and warmth.  Some report an experience of meeting their deity or previously deceased loved ones.  Rarely this experience is one of terror, and there are documented case reports of Post traumatic stress disorder.  This drug is excellent but has some issues.

Nurses should comfort the patient and prepare them for a sensation of "passing out". Tell them that you will stay with them and keep them safe.  Hold their hand.  They are often very frightened.

Have you had a patient on this drug?  Tell us your story.

#KYJ - HbA1c in Brief

Understanding HbA1c (#knowingyourjargon)

Smooth RBCs  are kind to your blood vessels, but sugary sticky ones damage the walls stimulating the inflammatory system that initiates cholesterol to be sent out from the liver to repair the damaged walls.

Red blood cells live 120 days.  During that time they slowly accumulate glucose and the haemoglobin protein (most famous for transporting oxygen) becomes glycated.

This glycated haemoglobin is measured as a percentage (old measurements) or in mmol/mol

The test for this stickiness of red blood cells is called HbA1c

As a percentage less than 6% is normal.
More modern tests measure in mmol/mol where less than 42 is considered normal.

Diabetes is commonly diagnosed with HbA1c levels above 6.5% or 48 mmol

Unlike a random BSL, the A1c test looks at glucose control over a period of 3 months, and is accurate as a control monitoring test for diabetics.