Infections and Psoriasis: A Causal Relationship

Shiva: My name is Shiva Mozaffarian and I’m here today to discuss the relationship and risks associated with infections and psoriasis. Joining us for this discussion is dermatologist and skin pathologist Dr. Seth Forman and a member of the psoriasis community Katie Chambers. Dr. Forman is the founder of ForCare Dermatology in Tampa, FL. His clinical specialties and research focus includes psoriasis, atopic dermatitis, and a range of other skin, nail, and hair diseases. Additionally, he has been published in the New England Journal of Medicine, The Lancet, Journal of the American Academy of Dermatology, and many others. Katie who has had psoriasis and psoriatic arthritis for 29 years has been battling numerous infections over the last few years which includes several hospitalizations. Katie became active with the National Psoriasis Foundation in 2016 participating in Team NPF events and advocacy efforts. Since becoming involved with NPF Katie said, “I discovered a whole world of people who have/had psoriasis as bad as I did, some worse. So, I feel less alone.” This topic, in fact, was brought to Psound Bytes™ from Katie. Let’s hear her story and from Dr. Forman what is the relationship between infections and psoriasis, and how infections can be managed. 

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Shiva: Welcome Dr. Forman and Katie! It’s a pleasure having you here today. Katie, let’s begin our discussion with your story of when your infection began. When did you first notice symptoms that indicated you had an infection and what did you do?

Katie: I didn't recognize it as an infection at first. I thought it was a bad flare. And it was scheduling with Dr. Forman,  having Dr. Forman look at it, and having him say this looks like an infection for me to say oh this is an infection. He prescribed antibiotics and it seemed to clear up. And then a month or so later it returned full force with blistering and sloughing off skin.  It  no longer looked like psoriasis.  I called to schedule with Dr. Forman again. He was on vacation. They worked me in to see his nurse practitioner who diagnosed cellulitis, which is a form of infection. At this point my psoriasis had flared, fully involved at this point and the infection had continued to worsen and they actually ended up having me in the hospital for about 6 weeks. They did a surgical debridement at that point. That's kind of where we've been ever since, where we've still got these spots that are weeping but the blistering is gone. The places where they've dug out skin are now filled in again. It's just getting it fixed for the final time and you know, when the psoriasis worsens, the infection worsens. When the infection worsens, so does the psoriasis. 

Shiva: And Dr. Forman, do you have any comments you’d like to add about Katie’s story?

Dr. Forman: In Katie's situation for what she shared, a lot of her story is the fact that it wasn't just that she had an infection, it was evident that she had an infectious process, most likely bacteria. I believe that was cultured and treated effectively a number of times with some multiple office and hospital visits over a few month course. But what I believe really provoked or propagated the infectious agents (which we all have on our skin, whether you have psoriasis or not) is the severe stasis dermatitis combined with uncontrolled psoriasis really caused an incredible flare, as well as incredible compromise of Katie's health during that acute period. 

Shiva: And Dr. Forman, can you provide examples of the types of infections that can occur in someone with psoriasis?

Dr. Forman: So, most importantly, people with psoriasis have an aberrant epidermal keratinization of the skin as well as below the epidermis, within the dermis, and the subcutaneous fat, within the vasculature they have an improper or an unregulated immune system. Therefore just like most patients that have some type of autoimmune process, whether it’s due to an interruption of the skin barrier or just due to having an interrupted or odd immune response, they also can be affected by bacteria and cause a flare of their respective condition. The bacteria that can cause flares are streptococci, staphylococci, which are known as epidermal pathogens. And then there's also helicobacter pylori, which is the gut bacteria which has been known to cause ulcers. It also can trigger psoriasis as well. Also, porphyromonas gingivalis and chlamydia. There are also some fungi such as candida, which can cause a flare of psoriasis, as well as viruses including HIV and hepatitis C. So there are a number of different type of organisms which are not all bacteria but also fungi and viruses that can cause a trigger of psoriasis. As well as some patients which have HIV and hepatitis C those are viruses that are inherent and are systemic. These patients also have to be monitored and treated perhaps differently than other patients. 

Shiva: So you mentioned staph infection which is a type of bacterial infection. We know that people with psoriasis are four to five times more likely to have staphylococcal on the skin. Can you elaborate on what staph infection is and what is the relationship to psoriasis?

Dr. Forman: Well, staphylococcal bacteria as well streptococcal bacteria are gram positive organisms which can be normal flora of the skin, not just in patients with psoriasis but also non-affected patients. It is known that these gram-positive bacteria can cause a trigger of psoriasis independent of stasis dermatitis or some other breaking of the skin barrier. Therefore, these patients that are somewhat immune compromised, although not as much as other patients with autoimmune disease, should be very careful in exposing themselves. Frequent hand washing in order to prevent themselves from becoming colonized and perhaps even infected by one of these bacteria.

Shiva: In addition to the bacterial infections, viral and fungal infections may also cause or exacerbate psoriasis. A type of fungal infection that we hear a lot about is Candida. People with psoriasis tend to be more prone to candida. Dr. Forman, why is that?

Dr. Forman: These patients, oftentimes with psoriasis, they have higher BMI’s than patients that are not affected with psoriasis. Obesity is far more common in patients with psoriasis than patients that do not have psoriasis. Candida alone without even considering some type of therapeutic agent for psoriasis is known to occupy areas under skin folds, such as in women under the breasts, as well as in the perineal area. In men, under the arms, as well as between the legs and perhaps the gluteal cleft. So these are areas where they are moist as well as they are very, very likely to be affected by candida. Another element that should be considered is that patients that are on therapy of the IL-17 pathway. At this time, there are two IL-17A medications, as well as one that's a receptor antibody. Patients that have therapy that interrupts the immune response in the IL-17 cytokine are much more likely to develop candidiasis. 

Shiva: And another type of fungal infection is Malassezia. What is it and what is its association with psoriasis?

Dr. Forman: Malassezia, I don't see very commonly in my practice as being associated with psoriasis. It’s a common inhabitant of the skin. It's caused by Malassezia furfur, and it causes pityrosporum folliculitis as well as some other skin conditions. I don't normally associate it with psoriasis. I find that Candida is a much more likely agent.

Shiva: And Dr. Forman, we've heard a lot about viruses lately, especially with COVID-19. How might a viral infection impact psoriasis?

Dr. Forman: Well, we need to differentiate between the systemic viral illnesses such as HIV or hepatitis C, which there are therapies for. In fact patients that have hepatitis C should be managed by their GI doctor and there is now a cure for hepatitis C. So it's important that these patients are clear of their hepatitis C prior to starting any type of immune modulating agent. For instance, we use a lot of biologic therapy as well as now are starting to have some JAK inhibitors or TYK 2 inhibitors that can help treat psoriasis. It’s important these patients are clear to their hepatitis C. HIV is a different matter. If a patient is undetectable in their viral load and their T cell count is normal, then they can be treated like any other patient that's not affected with HIV. In my practice, I have a number of HIV positive patients that are undetectable and have a very high T cell count, and therefore they are candidates and have been enjoying clearance on some of the more modern biological therapies without complications of their HIV. Some of the other viruses, such as COVID-19, initially approximately 3 years ago, it's now early 2023 we were considering stopping all patients on any biologic therapy for psoriasis because of the pandemic. Later, thanks to a lot of early and quick research by both the rheumatology and dermatology intelligentsia, we find that there's really no known reason to stop biologic therapy in the event of a pandemic, and even in the event of a patient actually acquiring COVID-19. So it's known that we should not interrupt therapy at this time, and I don't interrupt therapy and I've had no known complications with any of my patients during the pandemic that I felt was due to continuing a biologic therapy.

Shiva: So Dr. Forman, could having a comorbidity such as heart disease or diabetes complicate risks of an infection?

Dr. Forman: Yes, diabetes certainly always complicates risk of infection, especially if a patient has severe stasis dermatitis. It's sort of a constellation of issues which can make an infection very, very prevalent, as well as, very welcoming to an infection and must be monitored carefully. It's important to monitor the fluid balance of these patients, as well as, continuing to keep their blood sugar in check. A low blood sugar, similar to keeping HIV in check, these patients mainly have a normal immune system or an immune system similar to a non- diabetic psoriasis patient. So if we can keep our patients well controlled, then they essentially are gonna behave similar to a non-diabetic patient. As far as heart disease is concerned, I don't believe there's any increased risk of infection with a patient that has heart disease. It's very important if a patient does have heart disease or congestive heart failure, it's likely that you should avoid a TNF alpha inhibitor type of medication. I believe there's at least three that we use in dermatology and there's probably two or three more that are used more commonly in gastroenterology and rheumatology. But the TNF alpha family of medications should be avoided in patients that have known heart disease and congestive heart failure. 

Shiva: We've spoken a lot about the types and risks of infections there are associated with psoriasis. Let's now talk about how infections are treated. Dr. Forman, when you see someone with an infection like Katie, what steps do you take to first assess and then treat the infection?

Dr. Forman: In the case of Katie, I was relatively certain that she had a severe infection and that it was going to require hospitalization. So I encouraged or demanded that she go to the emergency room and not just go home on oral antibiotics. So in that situation, it's imperative if you recognize signs and symptoms of potential sepsis, meaning that you're extremely warm, your legs are warm. You're maybe short of breath. You may not feel entirely oriented. Those are signs that you're not OK to stay home. Those are signs that you may not even wanna go to your dermatologist. Those are signs that you may want to go straight to the emergency room or a walk-in clinic that can then monitor you and determine whether or not you need to go on to an emergency room. That is not the type of thing that you wait also a month or two to get your appointment with your dermatologist. That is an acute situation. It means you're very sick and you could possibly be dying. In fact, people do die of sepsis. So, it's important that you recognize this with either of those symptoms, including a fever. Although, some patients who are severely immune suppressed, they may not even mount a fever. You may have a normal temperature in light of the fact that you still have a pretty severe infection. So, it's important for you to recognize that and act urgently if not emergently. 

Shiva:  And will immune modulating therapy impact the progression of a severe infection?

Dr. Forman: It's certainly possible, and there are different therapies that can impact different types of infections. Such as we discussed a few minutes ago, there are IL-17 blockers that are more likely to cause a yeast or candida infection. There are TNF alpha blockers. TNF alpha blockers that are more likely to cause bacterial infections. If you're not feeling right, I recommend and your due for your next dose, and you're not feeling 100% either because of some of the symptoms that we just talked about, it's better to make the phone call to your dermatologist if you're having severe symptoms like we just discussed, it's very important that you either visit a walk-in clinic or a emergency room. And skip that next dose until further instructed by your healthcare professional.

Shiva: So Dr. Forman, we spoke about gut microbiota earlier. Do you feel this is a promising area for development of therapies to treat both psoriasis and infections?

Dr. Forman: So my answer to gut bacteria, I believe the jury is still out. I don't know exactly how we're going to address that now and in the near future. However, there is a lot of research being done both in the therapeutic area and also in the way that it may contribute to the progress of the disease. So stay tuned regarding gut bacteria in psoriasis.