Infestations and infectious diseases of the skin

this is a video on infestations and infectious diseases of the skin we have a lot of diseases to cover so let’s get started so you lightest is a bacterial skin infection that creates a red tender plaque often on the lower leg you might see streaks of Linfen of lymphangitis to the lymph nodes this is a good example of a cellulitis that kind of spreads through the arm through the lymph lymphatic system of the arm starting from cellulitis this can have systemic symptoms like fever and high white blood counts tender lymph nodes and pain in the affected areas risk factors for cellulitis include trauma wounds systemic infection adem├ís inflammatory State and bug bites so your life this is most often caused by group a strep and staph aureus treatment for cellulitis is oral antibiotics usually cephalosporins doxycycline SMX TMP clindamycin for outpatients for inpatients you do want to make sure you cover hospital-acquired MRSA so you want to use vancomycin erysipelas is a specific kind of cellulitis this is a more superficial shiny demarcated cellulitis as you can see in that image on the left there and you can see that it’s very demarcated the borders are very abrupt in air syphilis compared to those of normal cellulitis in this bottom right image here there Silla erysipelas notably affects dermal the the dermal lymph nodes usually on the face or on the legs and it’s usually caused by group a strep strep pyogenes specifically so to treat that you want to use oral antibiotics that cover group a strep and to affect that to elevate to the affected area impetigo has another skin infection this is a more superficial bacterial infection it often occurs in children that are 2 to 5 years old and it can spread among contacts that presents with red papules that enlarged a farm a golden crust you can kind of see that golden crust on this person’s face here and in this illustration of course the classically described is having a honey crusted appearance it’s usually caused by group a strep or staph aureus and Bullis impetigo is a variant of impetigo that has flaccid Bully containing yellow fluid caused by the staff exotoxin treatment for impetigo is the rosen intimate or oral antibiotics that cover both pathogens like cephalosporins or macrolides abscesses are large masses on the skin they are usually red warm and tender they can drain pus or fluid you treat abscesses by doing inds incision and drain if the patient has multiple abscesses immunosuppression or other cellulitis you do want to use oral antibiotics in those patients just to ensure it doesn’t spread and just to kind of cover all the absences all the abscesses at the same time it’s it’s unpractical to do multiple IMD’s if there are that many lesions sort of knowing the definition of a fer uncle which is a small peri follicular abscess often seen that’s like a boil also a carbuncle is a large congregation of furuncles several small peri follicular abscesses and they form one large inflamed unit that can discharge pus both for uncles and carbuncles can occur in hairy areas that are exposed to friction sometimes after shaving usually caused by staph aureus you can treat for uncles and carbuncles with warm compressions if they’re small and if they’re pretty big you you want to treat them as an abscess that is do an I&D on them folliculitis is similar it’s an infection of a hair follicle it looks like a small red pustule with pus it’s usually caused by staph aureus and if a person has folliculitis after being in a hot tub or being in warm water you want to consider Pseudomonas that’s bacteria that’s often present in hot tubs treatment for folliculitis is to clean the affected area with soap and water multiple times daily you want to avoid shaving that area because that could be the cause of folliculitis you can also administer oral or topical antibiotics or drain if it’s severe next is Staphylococcus scalded skin syndrome this is when you have a secretion of staph aureus toxin into the bloodstream that causes systemic blisters the skin peels away in sheets in SSSs the wound cultures here are negative it’s important to note that it’s caused by the stem aureus toxin not the actual bacteria risk factors are children under two years old and patients with renal disease necrotizing fasciitis is a bacterial infection that spreads to the fascia a deep layer of connective tissue and this can spread very quickly throughout the skin these are exempt this is an example of necrotizing fasciitis how it starts and how it progresses to kind of spread throughout the entire skin these are usually described as pain unproportional in the physical exam findings so this doesn’t look like it be all that painful but the patient might be writhing in pain it rapidly expands to a rash with often ill-defined plaques and characteristic

purple dark discoloration and it spreads quickly this is another medical surgical emergency with a high mortality rate treatment here is to refer surgery immediately they need to cut this open they need to pull out all the bacteria wash it all out and administer a broad-spectrum antibiotics that that covers group a strep and staph another cutaneous manifestation of infectious disease is secondary syphilis secondary syphilis is the second stage or second presentation of a sexually transmitted disease syphilis that’s caused by a bacterium Treponema pallidum usually presents with a diffuse rash that involves the hands and the feet palms of the hands and the soles of the feet it can also have symmetrical reddish pink non itchy rash on the trunk and extremities but usually you’ll see this maculopapular rash on the hands and on the feet this often has systemic symptoms as well malaise fever headache stiff neck myalgias but this is very variable not everybody has these systemic symptoms you can diagnose this with immuno stains 40 pallidum serologic tests 40 pallidum a lot of times patients will remember having a syphilis Shanker before and that would’ve been the first presentation of syphilis you treat syphilis with penicillin G pediculosis is the common lice infection pediculosis capitis is another name for it it’s lice infestation of the human head caused by the louse and this causes scalp itchiness Minna mine also caused posterior cervical lymph adenopathy adult lice or eggs can be seen in the skin they’re usually not movable along the hair shafts they kind of hold onto the hair shafts and you they get stuck and you can’t really pull them off and that’s that that helps differentiate them from hair casts children get these more in adults and african-americans get them less than other races due to the difference in their hair structure there are other varieties of pediculosis there’s also a body louse there’s a pubic crab louse and the treatment for particular –ss is an over-the-counter of 1% permethrin lotion you can also use a topical ivermectin cream or a malathion you can also physically remove these with a comb and it’s important to wash everything wash the washing vacuum sheets rugs carpets everything that uh that might have been infested with the lice scabies is another infestation this is also known as a 7-year itch it’s a contagious skin infection caused by a mite these commonly presents as itchiness with a red pimple like rash occasionally tiny burrows can be seen in the skin you might be able to see their little tunnels that they create in the epidermis these burrows as we said are linear markings representing the Librium linear movement of the mites under the skin escapees are common on finger webs umbilicus breasts axilla scrotum penis and in the waistline all ages get scabies all socio-economic statuses also get scabies women get them more than men children get them more than adults and they’re coming in group settings like dorms or retirement homes diagnosis for scabies is skin scraping you can look at it under the microphone under the microscope do a mineral oil prep and see mites eggs or feces under the microscope you tree scabies similarly too you use a permethrin cream that you want to apply from the neck down the entire body from the neck down also oral ivermectin and wash and vacuum everything bedbugs are another infestation these are human parasites that feed on human blood they’re found in bedding and sleep areas and they’re often active at night the most common bed bug is SIMEX latakia laris the saliva of bed bugs has antiplatelet agents anticoagulant agents and basal dilators that help them get access to your bloodstream the host presents with a demitasse papules scattered all over the body as you can see in that image here the treatment for bed bugs is that the bites resolved in a week or two but like the other infestations you want to clean everything perhaps hire an exterminator if the lesions are bothersome you can use an anti itch cream or a steroid for symptoms but the symptoms should resolve in about a week or 10 days next we’re gonna give into viruses or diseases caused by viruses lastly some fungus so we’ve done bacteria we’ve done some infestations we’ve done and we’re gonna do viruses and fungi so chicken pox chicken pox is also known as very sello it’s caused by the varicella zoster virus and the initial infection happens and presents as diffuse vesicles on an orthopaedist base vesicles can be in various stages of healing and

extensive across the body as you see in this upper picture here this is chickenpox in a young child you can diagnose chickenpox with PCR with a zinc prep with a culture or with the direct fluorescent antibody however to differentiate chickenpox from other herpes viruses you want to use a direct fluorescent antibody or PCR is probably that is probably the diagnosis of choice Tseng prep cannot differentiate between chickenpox and herpes simplex and we’ll see more that in a second herpes zoster is also known as shingles was caused by re-emergence of that same virus vzv virus he presents as a painful skin rash and a localized dermatome while distribution as you can see in this bottom image here that’s one single dermatome horizontal stripe across the body and that’s how herpes zoster since they reimburse from the dorsal root ganglia and affects that entire dermatome the rash contains vesicles on an erythema to space just like chickenpox did the vzv only occurs in once and this is in comparison to HSV which can recur multiple times we’ll talk about herpes simplex more in a bit when I diagnose herpes zoster with PCR you can also use a zinc prep but those do not help you differentiate between vzv and HSV you treat herpes zoster with acyclovir or valasek LaVere to reduce the length of the episode and to end to kind of treat that neuralgia that nerve pain that you get associated with herpes zoster next is herpes simplex this is caused by the herpes simplex virus 1 or 2 and it’s a rash presents as a painful rash often around the mouth or nose or buttocks or thigh or in genitals HSV one tends to prefer the mouth in the nose beaches B 2 tends to prefer the lower body mohab below the waist but those are not hard and fast rules both viruses can affect both places the rash contains vesicles and pustules on an erythema to space like the other herpes viruses this recursion or than once unlike zoster unlike herpes zoster and often occurs in the same place to diagnose herpes simplex munis PCR again you cannot differentiate between vzv and HSV using just a zenk prep a viral culture or a direct fluorescent antibody treatment for herpes simplex is acyclovir this can make your episodes more mild or you can use a cycler to prevent a recurrence of herpes simplex hepatic Whitlow is when you get herpes on your finger and this used to happen a lot in medical settings where people didn’t use gloves and they were examining patients examining the mouth for instance you would get herpes on your finger from the patient next is Kaposi sarcoma this is caused by human herpes virus 8 a cell of origin here is the endothelial cells so it’s a proliferation and malformation of endothelial cells the sarcoma presents as a dark of violaceous plaques or nodules on the skin and mucous membranes Kaposi’s sarcoma usually occurs in patients that are immunosuppressed such as transplant recipients or patients with AIDS you want to prevent Kaposi sarcoma with antiretroviral therapy in patients that have AIDS you can treat busty sarcoma by resecting the the lesions if there’s only a few of them so if it’s only these two you might be able to resect with them them but if you have systemic disease that’s everywhere it’s no longer practical to resect everything and you want to use chemotherapy the Ruka vulgaris this is the common wart these skin lesions present as raised exofit ik papules with a rough surface you can see how these are excess Finnick they’re growing outwards and they look rough these are coming on the hands but can grow anywhere on the body they can spread especially with trauma now this happen equally in men and females but they are often common in school children and young adults these are caused by the human papilloma virus the HPV virus that infects the basal layer of the keratinocytes there are subtypes of of these viruses that kind of determine their morphology so there’s Veruca planing or flat warts and these are usually it’s pink smaller smoother and actually dome-shaped as opposed to these which don’t really look like a dome they look like outward exofit ik growths there’s also a poem or plantar Veruca which is a thick and Dafydd ik imaginating papule the course of warts usually resolve but they can take two to five years so to get rid of them on your own you might want to use cryotherapy cellie cyclic acid but this of course can leave hyperpigmentation or scars or blisters but if you want to get rid of a wart you can do it they sometimes resolve on their own but it might take several years there’s also genital warts also caused by HPV human papillomavirus these are Cecil EXIF attic plaques on the external genitalia the perineum the peri anal region and the inguinal folds there’s extensive infection in

immunocompromised people people that have undergone organ transplants or HIV patients HPV types six and eleven typically cause genital warts and recall that 16 and 18 cause the high-grade intra epithelial neoplasia can lead to cervical cancer you can prevent for all these types of HPV using guard sill a vaccine for HPV and the treatment for HPV is to essentially freeze the warts off to use electricity to fruit to get the warts off laser surgery and mikvah mod which is a toll-like receptor seven and eight agonist which would stimulate the immune system to take care of the warts now back to some fungi molluscum contagiosum these are also called water warts but they’re not caused by HPV like the other ones these are viral infections of the skin oh excuse me molluscum contagiosum is caused by the pox virus we’re gonna get to the fungi in a second molluscum contagiosum is a viral infection of the skin and occasionally mucous membranes these cause numerous small flesh color to clear or smooth papules with central and the location this can be on the face the trunk of the extremities or it can be a sexually transmitted infection and appear on the genitals it’s caused by pox virus a very large virus treatment is not required because they usually go in on their own to reduce the spreading of these you can consider cryotherapy to get them off dermatophytes these are the fungi there’s a lot here they’re usually named according to where they infect so tinea pedis for instance would be a dermatophyte that affects the foot this is also called athlete’s foot tinea pedis has it grows in an area that creates moisture that’s the shoe people usually get affected with tinea pedis and like a public gym a public pool or showers tinea pedis presents with scaling and redness it often occurs and there’s three patterns it can be interdigital which is between the toes it can be a vesicular bulbous which is kind of large all over and has blistering appearance or it can be a moccasin type which affects the sides of the feet up to where like low-hanging socks or the moccasin shoes would would touch Atena penis can also involve the nails which is called onychomycosis and if it does involve the nails you do want to use oral antifungals to get rid of it because you have poor access to under the nail beds with topical antifungals you can treat tinea pedis with the hygiene you can change your socks or use a foot powder to keep your feet dry you can also use topical antifungals like imidazoles which are fungus static you can use allah means which are fungicidal you could use cyclo perixx which is both longest attic and fungicidal now one of the main complications with tinea pedis is that it can lead to lower leg cellulitis the fungal infection kind of breaks the skin and creates portals of entry for the bacterial tinea corporis as another dermatophyte infection this time infecting the trunk and limbs this is an example of tinea corporis here it’s a ringworm and it’s it’s not so really caused by a worm it’s not caused by worm at all it just forms this ring appearance ring shaped lesion with a central clearing and that’s called ring worm tinea corporis causes itching it affects all the ages and it’s often asymmetric you treat it similar to tinea pedis so you can use oral antifungals terbinafine and fluconazole in severe cases tanea chorus is similar but occurring in the groin area tinea capitis this is a dermatophyte that affects the scalp and the hair as you can see in this upper image here Tamia capitis is more common in children african-american children specifically 4 to 8 years old is the most common range it spreads through contact with animals and presents as a there’s several presentations to it it could be a black dot it could be a carrion which is an abscess with pus it can be a seborrheic spot which is an oily spot usually there’s broken hairs in that area too so this looks like it might just be black dot tinea capitis and you can see there’s a bald spot there too as a result of the fungal infection are through spores can be seen in hair shafts on microscopy that’s one way to diagnose it and you treat this disease with griseofulvin terbinafine orally topicals do not work in the hair species that might cause a dramatic infection our trichophyton microsporum and epiderm feyten and these are the most common species that cause fungal infections and they’re all kind of caused by the same species you can diagnose these dirt matta Finnick infections with the Koh exam this potassium hydroxide exam is essentially taking a piece of the affected area dissolving it with Koh which kind of dissolves the keratinocytes then observing under the microscope for any kind of hyphae or other indicators of Jim mattifies so again you see septate and branching – on the microscopy and it’s important to note that these septae are branching – need to extend past the length of one cell and that’s to help you differentiate the

actual fungus the actual hyphae from common fibers that might be seen in the outer layers of the skin and these demenna fights usually are limited to the epidermis so they do not cause systemic infections from where you see them here another disease is tinea versicolor also known as pityriasis versicolor this is an eruption of macules and patches on the skin and as the name implies versicolor they can be many colors they can be tan salmon hypo pigmented patches or macules they’re usually appearing on the trunk as you see in this image at the bottom they’re not visibly scaly but if you can feel them you would feel that they are a little rough and you might be able to see some scale if you rub it these are seen better in the summer with tan or pigmented skin or in darker skinned individuals these are caused by yeast the malassezia yeast which is not actually in dermatophyte which is a bit confusing those are called tinea versicolor but it’s caused by a yeast not an errata fight to diagnose tinea versicolor you can confirm that there’s an actual fungus there with the Koh exam you would see short hyphae and small round spores of malassezia on microscopy treatment for tinea versicolor is anti dandruff shampoo hazel creams or one oral dose of a nasal scaling stops quickly and you clear the infection pretty quickly but the repigmentation of the skin might take a bit longer lastly we’re going to talk about candidal intertrigo which is a burning red rash usually occurs under large skin folds such as the groin the armpits under the breasts the buttocks the abdominal folds and especially happens in obese people you can also happen between the finger and the toes predisposing factors are hot humid weather and in people who are obese with low motility who can move around much we might get hot sweaty moist in those areas diagnosed with koh exam like the other fungal infections treat this with topical antifungals like polyenes imidazole you prevent chemical intertrigo with better hygiene and you want to limit steroid use one more disease that’s caused by fungus is diaper candidiasis this is presents in infants with red erosions to the diaper area you often see satellite lesions in diaper candidiasis because it’s caused by Candida a fungus that can kind of spread out to other areas from the diaper area this involves the skin folds and it’s important to note that it involved the skin folds because that helps you differentiate it from contact dermatitis or diaper dermatitis pathogenesis in kenton diaper candidiasis is that the urease and the feces breaks down urea from urine to ammonia so you’re breaking down urea into ammonia ammonia then irritates the skin and the Canada that is present in the feces can then enter the skin you treat diaper candidiasis with a nice Dutton or midazolam Zoran mints again you want to limit your steroid use you don’t really want to treat any kind of fungus with steroids you want to use anti-fungal agents steroids tend to spread a fungal infection if you apply steroids to those areas so again to differentiate diaper candidiasis from other disorders you want to know that canna diocese has satellite lesions Kenna diocese does not improve with barrier creams because it’s not a contact dermatitis can a diocese involves the skin folds whereas irritant dermatitis would spare the skin folds and of course Koh examined fungal culture can reveal diapered candidiasis this has been video on infectious diseases and infestations involving the skin I hope this was helpful and thank you for listening