Genetics, Immunity, and Infection in Everyday Nursing Care

Heather Murphy

Welcome to the show! I'm Professor Murphy, and I want to start with something wonderfully ordinary: a patient tells you, “High blood pressure runs in my family, my sister has lupus, and every time I take that pain medicine, I get so sick.” That is not small talk. That is CLINICAL data.

Heather Murphy

In nursing, genetics matters because it helps explain why two people can live in the same town, eat similar food, catch the same bug, and still have very different outcomes. Genetics is the study of inherited traits passed through genes. Genomics is the bigger picture -- how all of a person’s genes interact with each other and with the environment. And pharmacogenetics is the part that makes students lean in a little, because it asks: why does one medication work beautifully for one patient and cause side effects or poor response in another?

Heather Murphy

I always tell students to think of it like this: genetics is the instruction manual, genomics is how all the chapters work together, and pharmacogenetics is what happens when that manual changes how the body handles a drug. Not every patient reads the same medication “recipe” the same way. Some metabolize drugs faster, some slower, some are more sensitive. So individualized care is not fancy extra nursing -- it is safe nursing.

Heather Murphy

Family history is one of the cheapest, fastest assessment tools we have. If inflammatory disease, autoimmune disease, diabetes, heart disease, or recurrent infections show up across generations, that should make you listen differently. Maybe the patient has inherited risk for an immune disorder. Maybe there’s a hereditary pattern tied to inflammation. Maybe their medication response will need closer monitoring. You are not diagnosing from a family tree alone, of course, but you ARE recognizing cues.

Heather Murphy

Now, layer that onto the immune system. The immune system has three big jobs. First, defense: identify and fight pathogens. Second, homeostasis: clean up damaged cells and help restore balance after injury or illness. Third, surveillance: keep watch for abnormal cells or threats before they become a bigger problem. I mean, it is basically the body’s security team, housekeeping team, and early warning system all rolled into one.

Heather Murphy

And when that system misfires, the consequences show up everywhere. Too little immune response, and the patient becomes more vulnerable to infection. Too much, or the wrong kind, and you can see allergy or anaphylaxis. If the body attacks itself, that’s autoimmunity -- conditions like rheumatoid arthritis or lupus. And if inflammation keeps smoldering over time, you get chronic inflammation, the kind that slowly affects joints, organs, energy level, and quality of life.

Heather Murphy

This is why everyday nursing assessment matters so much. The med-surg nurse is often the one who hears the pattern first: “My mother had this too.” “I’ve always reacted badly to that drug.” “These flares keep coming back.” And if you’re thinking, okay, so what do I DO with that? -- you document it, you connect it to the current presentation, and you use it to anticipate risk. That is how careful bedside nursing turns scattered details into meaningful clinical judgment.

Heather Murphy

Let’s build the immune picture a little more, because once you understand the body’s response patterns, assessment starts to feel less like memorizing symptoms and more like reading a story. The first distinction is active versus passive immunity. Active immunity happens when the body is exposed to a pathogen and creates its own antibodies, such as when someone is exposed to the flu virus. Passive immunity happens when antibodies come from an outside source rather than from the person’s own immune system, such as with a vaccine.

Heather Murphy

Then we’ve got the white blood cells -- and yes, students mix them up all the time, so here’s the quick bedside version. Neutrophils are the first responders, making up about 50 percent of the white blood cell population, and they jump in early with bacterial or viral infection. Eosinophils fight pathogens and show up in allergic-type responses. Basophils release histamine and other chemicals that drive inflammation, especially in allergic reactions. Monocytes are the cleanup crew; they help remove damaged or dead cells. And lymphocytes, the B and T cells, produce antibodies and kill pathogens. It’s basically a hospital team: triage, alarm system, cleanup, and targeted specialists.

Heather Murphy

When infection hits, the body mounts an inflammatory response. That can mean fever, because the hypothalamus adjusts the body’s thermostat. It can mean fatigue, pain, swelling, redness, and if things escalate, organ dysfunction. Those are not random complaints. They are cues.

Heather Murphy

Now, infections can present in patterns. A localized infection stays in a small area -- think abscess. Disseminated infection spreads beyond the original site to other areas of the body. Systemic infection spreads extensively, often through the blood, and that is where the stakes get much higher. If you’ve got a patient who goes from “my wound is sore” to fever, weakness, altered perfusion, or organ changes, your nursing brain needs to get very alert, very fast.

Heather Murphy

Bacterial and viral infections both trigger immune responses, but clinically we care about identifying the likely source, route of spread, and severity. Pathogens can spread through skin contact, body fluids, feces, airborne transmission, or contaminated food and water. We also have to think about antimicrobial-resistant infections -- multidrug-resistant organisms like MRSA or resistant Enterobacteriaceae -- because treatment choices become more limited.

Heather Murphy

And this is where one of those classic nursing questions comes in: why do we get cultures before antibiotics when possible? Because once antibiotics start, they can reduce the ability to identify the actual organism. Culture first, then treat, when the patient’s condition allows. Not because we enjoy extra tubes and labels, but because targeted therapy matters. Antibiotic stewardship matters. Guessing wrong has consequences for the patient and for public health.

Heather Murphy

So at the bedside, what matters? Early recognition. Isolation or infection-control precautions when indicated. Good hand hygiene. Monitoring fever trends, pain, redness, swelling, drainage, respiratory changes, GI symptoms, and signs of worsening systemic involvement. Infection can move from manageable to dangerous faster than students expect. The nurse who recognizes the pattern early can change the entire trajectory.

Heather Murphy

Let's now talk about the difference between osteoarthritis and rheumatoid arthritis. I have seen students lump them together because they both have the word "arthritis" in them. Also because both involve painful joints, and on the surface... sure, I get it. But under the hood, these are VERY different disease processes, and nursing care gets better when you understand that difference.

Heather Murphy

Osteoarthritis is primarily about damage to articular cartilage. Over time, that smooth joint surface wears down. Common contributors include aging, trauma, injury, overuse, repetitive stress, obesity, genetics, joint malalignment, and even a sedentary lifestyle. As the process continues, patients can develop bone spurs and cysts. It can progressively worsen, and what patients feel most is often pain with movement, crepitus, stiffness, fatigue, and reduced mobility.

Heather Murphy

This is the most common arthritis, and it affects everyday life in very practical ways. Lower employment rates, more missed workdays, and real limitations with normal activity. Movement becomes harder, and then because movement is harder, health risks like obesity, diabetes, and cardiovascular disease can become more intertwined. It becomes a cycle.

Heather Murphy

Assessment-wise, diagnostics can include radiography like x-ray, MRI, or ultrasound, inflammatory markers such as ESR and CRP, and sometimes arthrocentesis to help rule out rheumatoid arthritis. A classic nurse assessment cue? Crepitus. That crunchy, grating feeling or sound in the joint that makes patients say, “Something in there just does not feel right.”

Heather Murphy

Rheumatoid arthritis is different. This is an autoimmune disease with chronic joint inflammation. Autoantibodies target healthy body tissue, and the synovial fluid lining the joints becomes inflamed. So instead of simple wear-and-tear, you’ve got the immune system attacking the joint. Patients may have flares and remissions, joint stiffness and swelling, pain, weakness, fever, malaise, and nodules that can range from pea-size to lemon-size. And it is not just about joints -- rheumatoid arthritis can affect organs too.

Heather Murphy

Lab testing may show elevated ESR and CRP, rheumatoid factor, and ANA assay results, with imaging helping assess damage. There are also treatment complications to watch for. Hydroxychloroquine at high doses can cause retinal damage. Long-term corticosteroid use can contribute to glaucoma or blindness. Some treatments increase infection risk, including tuberculosis concerns with anti-tumor effects. So nursing care includes not just disease management, but medication vigilance.

Heather Murphy

Here’s my plain-language comparison: osteoarthritis is more like the joint has been mechanically worn down; rheumatoid arthritis is more like the body’s immune system has picked the wrong target. Same address -- the joint. Very different cause.

Heather Murphy

Nursing priorities overlap in some ways: pain control, mobility aids, support with ADLs, psychosocial support, and patient education. But your teaching shifts depending on the diagnosis. For osteoarthritis, think activity support, weight and joint protection, and realistic mobility planning. For rheumatoid arthritis, add flare management, low-impact exercise, orthotics, PT and OT support, fall risk reduction, assistive devices, and watching for systemic complications. And do not underestimate the emotional load. Chronic pain, fatigue, job loss, depression -- those are not side notes. They are part of the disease experience.

Heather Murphy

Some immune and inflammatory problems are uncomfortable. Some are disabling. And some become life-threatening in a hurry. Peritonitis is one of those conditions that should make every med-surg nurse sit up straighter. It is inflammation of the peritoneum, and major causes include infection, trauma, and organ disease such as cirrhosis.

Heather Murphy

There are two broad types. Spontaneous peritonitis can occur as a complication of liver or kidney failure. Secondary peritonitis results from something like a ruptured organ. Risk factors include cirrhosis, ulcerative colitis, stomach ulcer, pelvic inflammatory disease, peritoneal dialysis, appendicitis, diverticulitis, pancreatitis, and a weakened immune system. If untreated, it can rapidly become life-threatening because of sepsis. That’s the piece I really want students to feel in their bones: this is not a “watch and wait” condition.

Heather Murphy

Patients on peritoneal dialysis are especially high risk, so infection prevention is huge. Thorough handwashing, wearing a surgical mask, cleansing the skin around the catheter with antiseptic, maintaining sterile supplies and equipment, and using PPE -- these are not fussy little rituals. They are sepsis prevention.

Heather Murphy

Then there’s lupus, a chronic autoimmune disease. Systemic lupus erythematosus, or SLE, is the most common and can affect tissues of multiple organs. Discoid lupus erythematosus, DLE, affects the skin and can progress to SLE. One classic finding in SLE is the butterfly-shaped facial rash, but the presentation can also include severe fatigue, hair loss, chronic pain, physical and cognitive impairments, and photosensitivity. Sunscreen is not cosmetic advice here -- it is practical disease management.

Heather Murphy

Triggers can include hormones, genetics, infection, stress, medications, toxins, Epstein-Barr virus, UV light, and silica dust. Lupus occurs mostly in females. Organ effects can involve the kidneys, central nervous system, cardiovascular system -- with increased risk for stroke and heart attack -- and serositis, meaning inflammation of the fluid-secreting tissues around the chest or abdomen. ANA testing is important; a positive antinuclear antibody test indicates a stimulated immune system. And a useful nuance: most people with lupus test positive for ANA, but not everyone with a positive ANA has lupus.

Heather Murphy

Now HIV/AIDS. HIV is a retrovirus that targets and destroys CD4 T cells. As CD4 counts decline, the immune system has more trouble fighting infection. Stage 1 is 500 or greater, stage 2 is 200 to 499, and stage 3 -- AIDS -- is less than 200. Early infection may be asymptomatic or look flu-like, with fever, headache, rash, or sore throat. With progression, patients may develop swollen lymph nodes, weight loss, fever, diarrhea, and cough.

Heather Murphy

What makes HIV so important in med-surg is not just the virus itself, but the opportunistic infections and cancers that can follow: tuberculosis, fungal and bacterial infections, CMV, Kaposi sarcoma, lymphoma. ART can reduce transmission risk and suppress viral load dramatically. PrEP can help prevent transmission to an HIV-negative person. But even with excellent treatment, the psychosocial burden -- stress, depression, isolation -- is real. Nurses care for the whole person, not just the lab trend.

Heather Murphy

Let's pivot to anaphylaxis now. Picture this: a patient was talking to you two minutes ago, and now they have facial swelling, wheezing, rash, dizziness, and dropping blood pressure. That is anaphylaxis until proven otherwise, and time matters.

Heather Murphy

Anaphylaxis is a severe allergic reaction that occurs after sensitization and can affect multiple body systems. Histamine release makes blood vessels more permeable, which contributes to hypotension. Patients may develop flushing, rash, edema, urticaria, nausea, vomiting, diarrhea, dizziness, confusion, headaches, or fainting. If it progresses to anaphylactic shock, cardiovascular and respiratory failure can follow. This is why we do not “just observe a little longer” when the pattern is obvious.

Heather Murphy

Common triggers include insect stings, food, medications, latex, and exercise. Higher-risk patients may have asthma, chronic lung disease, certain medication exposures like beta blockers or alpha adrenergic blockers, or mastocytosis. And if the trigger is unknown, referral for allergy evaluation matters, because prevention is part of survival.

Heather Murphy

Nursing priorities are beautifully clear here. Number one: AIRWAY. Always airway. Prepare for intubation even if it is not initially needed, because swelling can worsen fast. Number two: epinephrine. Standard treatment includes epinephrine, oxygen, and supplemental IV fluids. Epinephrine causes vasoconstriction, helping manage the blood pressure drop and poor tissue perfusion seen in anaphylaxis. IM epinephrine can be given in 0.3 to 0.5 mg doses every five minutes until manifestations start to resolve. In a hospitalized client, IV epinephrine may be used. But the headline remains the same -- epi FIRST.

Heather Murphy

From there, you support breathing, circulation, monitoring, and rapid escalation of care. And yes, part of the nurse’s role is prevention: identifying food, medication, and latex triggers in advance. So many emergencies are prevented by a sharp admission assessment and a nurse who actually reads the allergy list instead of just clicking past it.

Heather Murphy

Now let’s tie this back to pharmacogenetics, because this is where med-surg nursing gets more personalized and, honestly, more interesting. Pharmacogenetics recognizes that inherited differences can affect medication response. One patient may get the desired effect. Another may have poor response. Another may have exaggerated side effects. That matters in chronic inflammatory disease, in autoimmune disease, in pain management, and in any setting where medications are central to treatment.

Heather Murphy

We are not saying genes explain everything. They don’t. Environment, infection exposure, stress, adherence, organ function -- all of that matters too. But genetics helps explain why “standard dose, standard response” is sometimes a myth. And if you carry that mindset into practice, you start asking better questions: What happened last time this patient took this? What runs in the family? Are they having an expected response or an unusual one? Nursing, at its best, is never one-size-fits-all. It is careful observation, quick action, and the humility to remember that every patient’s body reads the script a little differently. Thanks for spending this time with me.