So hand infections are covered quite extensively on the examinations, and so we'll try to get through all of this information in the next 25 minutes. We'll review the epidemiology, we'll discuss infections in specific anatomic locations, and anything within the slides with the handouts that has an asterisk has been covered on the selfless examination in the past. Hand infections can be subcutaneous, they can involve a tendon sheath, joint, or bone. They can be related to direct inoculation versus spread from local compartments versus hematogenous dissemination. The most common organism will be Staph aureus, followed by strep and gram negatives. MRSA now is the most common community-acquired Staph infection, and it's increasing in incidence. Risk factors include IVDA, living in close quarters, prior antibiotic use, as well as extremes of age or immunocompromised state. And community-acquired MRSA tends to be a more significant infection due to the associated tissue necrotic enzyme with these infections. In order to decolonize a patient preoperatively, you can use merpericin that does decrease the rate of surgical infection greater than chlorhexidine, and we tend to use it in the NAIRs for about five days preoperatively. If you have an MRSA infection, surgical drainage is the most important component when you develop an abscess. Treat them with IV vancomycin. If they're allergic, you can try leniazid. In the examination, if the infection occurs at home or workplace, it's typically a single gram positive. If it's an IV drug abuser, farm, or soil injury, or a bite, or a patient with diabetes, consider a polymicrobial infection. In patients, or on the examination, the question involves a chronic indolent infection, consider an atypical mycobacterium or a fungus. As an examination of all patients, we take a thorough history, determine the extent of the process, obtain a good past medical history to see if there's any immunocompromising process. And again, on the examination, if the patient is a medical care worker or a toddler, consider herpetic whitlow. A gardener, possibly sportricosis. If it's in a marine environment, and this is hit quite commonly on the exam, consider mycobacterium marinum. Whereas animal farmers, meat handlers, consider tularemia, anthrax, or brucellosis. Typically we'll assess swelling, erythema, systemically, regionally assess for acing lymphangitis or adenopathy. Workup with x-rays. We're assessing for a foreign body, gas. If they have advanced osteomyelitis, it'll show up on an x-ray. With early stages of osteomyelitis, we can see edema on the MRI, and MRI is very helpful for assessing for an abscess and the extent of the abscess. Quite often we'll use ultrasound now in order to assess whether an infectious process has led to an abscess. It's also very helpful to ensuring that for an aspiration of a wrist joint, that actually in that radial carpal joint when the aspiration is performed. With a bone scan, it's rare that you get a bone scan. A positive bone scan just means there's a positive bone scan. It's a very sensitive study, but if it's positive, I still have to perform further workup. So it's uncommon that I'll use that unless I'm concerned about a more diffused process. Differential diagnosis could be inflammatory arthritis like gout, and if you're concerned about gout, the specimen that you sent should be an absolute alcohol. It could be acute calcific periorthritis if you see a calcific deposit on the x-ray. If it's a dermatologic process, consider pyoderma gangrenosum, which is a progressive dermatologic ulceration from just minor trauma, and you treat that with systemic steroids. We send our specimens for aerobic, anaerobic, and gram stain. If you're concerned about an atypical mycobacteria, remember Zeal-Nielsen stain, culture at 28 to 32 degrees, and we use a Lowenstein-Jensen medium. If you're concerned about a fungus, it's KOH prep for a microscopic exam, and herpes, we do a Zank smear. We unroof the vesicle and obtain a Zank smear looking for giant cells. Initial treatment with antibiotics is really dependent on the locale and the prevalence. Like in our location, MRSA is so common that we'll certainly cover MRSA for our initial antibiotic treatment. It's also dependent on the severity of the infection, comorbidities, and then final treatment is dependent on the ultimate culture and sensitivities. Again, IV vancomycin or clinomycin is our first line if we're very concerned about MRSA. If minimal comorbidities and a more minor infection, we'll use Bactrim clinomycin doxycycline. Prophylactic antibiotics for many of our soft tissue procedures, if it's a short procedure, has not been shown to be required. But if it's a soft tissue procedure that has no implant, if it's greater than two hours, prophylactic antibiotics has been shown to reduce postoperative infections. Remember the patient that's on a fluoroquinolone, on Cipro or Levoquin, that they may develop a tenosynovitis. They'll have this sudden onset of a severe pain along a tendon sheath. These are the more elderly patients. It tends to happen more in men than women. And a third of these patients will be on some form of corticosteroid either before or during their treatment. Now to specific infections in the upper extremity, we'll start distally, running from paronychia to more proximally, with deep space infections. So acute paronychia, it's infection of the nail fold, the epinechial fold. You disrupt that tight seal between the nail fold and the nail plate. And as we heard earlier, the hyponychium is that area in the distal aspect of the nail plate. And it's that distal part of the nail plate and skin that has the best resistance to infection. Acute pyreneic is the most common hand infection. Staph aureus is the most common offending organism. It can occur from nail biting, poor hygiene. If it's a cellitic process, consider soaks or antibiotics. Once you have an abscess, you need to consider an incision or drainage. Chronic pyreneic is that erythema, swelling around the nail fold, usually from keeping your finger wet or direct trauma to the area. And it's important to differentiate between a chronic pyreneic, which typically initially is not related to infection, but more of an inflammatory process, and acute pyreneicia, which requires incision and drainage. Chronic pyreneicia typically is treated with limiting the immersion of the digit in water. In patients with diabetes, make sure that their glucose is well controlled. And if they have a chronic process, you can consider a marsupalization, where excise the skin proximal to the nail fold and allow that tissue to heal by secondary intention. Inichomycosis, the most common reason for a fungal infection, is a dermatophyte, trichophyton. If it is a yeast, it's typically candidiasis. We usually culture the nail plate prior to treatment. If the infection is mild, we use a topical antibiotic. If it's mild to moderate and it's a dermatophyte, consider flurconazole and Canada itraconazole. If it's a more severe fungal infection, remove the nail and provide systemic as well as topical treatment. Pulp space infections, called a felon, these are very difficult to treat and eradicate just because of the fibrous septae within the pulp. Present typically with severe pain, usually related to some type of penetrating injury. Staph aureus, again, is the most common offending organism. And early treatment may help with elevation, antibiotics, and soaking. But again, once you have an abscess, incise and drain to limit pulp deformation or necrosis. If it progresses, you can lead to an osteomyelitis and a septic flexor tenosynovitis. With the incision and drainage, if it's a vulvar abscess, do a midline pulp space incision. If it's within the digits, we incise the non-border aspect of the digit. But try to avoid a fish mouth incision, since that will tend to lead to pulp deformation. A septic pyogenic flexor tenosynovitis is a rapidly spreading bacterial infection that's a surgical emergency. Staph aureus is the most common offending organism. It's a chronic infection. Consider a mycobacterium marinum. You'll see this horseshoe abscess quite often on the exam, where a patient will have an infection of the thumb and then develop symptoms in the small finger or vice versa. And that's related to the extension of the process around the wrist at peroneus space and then into the ulnar bursa, leading to the process more to the adjacent digit due to that transmission of the infection. For septic flexor tenosynovitis, we all know cannabis signs. Patient will hold their digit in a flexed posture. Tenderness along the flexor sheath is considered the most sensitive of the four. They'll have diffuse swelling, exquisite pain on passive extension of the digit. Emergent incision drainage is important. We used to use an indwelling catheter in order to drain the digit after the procedure, even at the bedside. And Neumeister has shown that by using the catheter, it probably doesn't change the results. The results are just as good as with intraoperative irrigation. With severe chronic infection, it's a full-wide incision, typically a mid-lateral incision, to completely drain the flexor sheath. It's important to institute early immobilization with therapies since stiffness is one of the most common complications of the process. Deep space infections, it could be a thenar space infection. Thenar space lies radial to that septum along the third metacarpal. The mid-palmar space is the deep space below the flexor tenons, ulnar to that septum on the third metacarpal. And peroneus space is the space just underneath the flexor tenons above pronator quadratus. Collar bed abscess, typically there's an injury in the web space between the digits. It can be held in an abducted position. And the path of least resistance is dorsal. So you may see the infection dorsally, but in these infections, you need to make an incision both dorsally and volarly since most of the infection actually will lie on the volar aspect of the hand. Septic arthritis, typical mechanisms of infection. You have to differentiate from gout or calcific pararthritis. Staph aureus is the most common, but in adolescent, make sure that you rule out Neisseria gonorrhea. Early incision drainage is important, and antibiotic coverage for approximately two to four weeks. Human bites, beware of that clenched fist injury. Any injury on the dorsal aspect of the MP joint should be considered an intra-articular injury until proven otherwise. These seem to be initially innocuous injuries, and these can lead to a significant infectious process. The problem is we tend to examine the hand in extension. The injuries occur with the digit at an MP joint inflection. So the time of your incision drainage, retract the extensor distally, assess that cartilage surface, and scrape that area of injury to prevent progressive infection. Dog bites occur more often than cat bites, but cat bites tend to be a more significant process just because of the length of the teeth and the thinness of the teeth. They tend to go deeper. The dog and cat bacteria typically is pastorella. This is most common. And we typically treat empirically with penicillin and Ancef, or we'll put them on Unicin or Augmentin. Spider bites, a widow spider will have a venom that has some neurotransmitter release, whereas a rescue spider just has some local necrosis, may need antivenom for a widow spider, whereas recruit spiders typically are self-limiting and may require some delayed debridement. Necrotizing fasciitis is often seen on these examinations. It's a life-threatening emergency. 20% of upper extremity amputations required often occur with necrotizing fasciitis. Most commonly seen in IVD-A, alcoholic population. Most common offending organism, Group A beta-helminic strep, but it may be polymicrobial. Initial appearance is benign, but then if the patient develops some hemodynamic instability with just the mild cellulitis, consider this being an early necrotizing fasciitis. Rapid surgical intervention is most important. You'll find liquefaction of the fat, but usually the muscle's not involved. It's above the fascia, and rarely do you have compromised deeper. We'll use broad-spectrum antibiotics. We add clindamycin. Poor prognosis, age greater than 50, other chronic illness. And again, the most important factor in recovery is an urgent and thorough debridement. Mycobacterial infections. 75% of atypical mycobacterial infections occur in the hand. It's usually an indolent, progressive infection. They can present six months down the line. Mycobacterium marinum is the most common of the mycobacterial infections that we'll see. Again, usually it's some form of marine environment. They can occur in a saltwater or freshwater environment. The skin test, as well as acid-fast smears, are usually negative. And on histology, we'll typically see caseating and non-caseating granulomas. Treatment is surgical debridement. Antibiotics typically are long-term, between six weeks and two years. If it's a more mild infection, a single-drug infection, we usually use clarithromycin or Biaxin. And if it's a more severe infection, multiple medications are required. Viral infection, herpes simplex, if it's a cold sore, type 1, or general herpes, type 2, both can cause herpetic whitlow. And these are those small, pus-filled vesicles that have a surrounding area of erythema that occur most commonly on the fingertip. They're usually self-limiting, and it's important that you differentiate herpetic whitlow from an abscess, and that if you incise and drain a herpetic whitlow, that can lead to a superinfection or encephalitis. It's the most common, or it's very common, I should say, in healthcare professionals, but most common infection that we see in toddlers. Again, we confirm the diagnosis with a Zank smear, and we use Valtrex in order to decrease the extent of the process. Toxic shock syndrome is more of a toxemia rather than a septicemia. It's usually associated with Staph aureus toxin 1 treatment to breathe the wound, remove whatever implant that you may have, and clindamycin. Sportricosis is the most common subtenuous fungal infection in North America. We typically see it in the upper extremity, and they'll have that characteristic nodular formation along the forearm. They'll tend to ulcerate. We'll see these in gardeners. We need to culture the lesion, and then treatment typically is with potassium iodide. Mucormycosis is an opportunistic infection in more immunocompromised patients. Usually starts as a small blackish area adjacent to an IV. It can progress relatively quickly, and so wide surgical excision with antifungal medications are recommended. A pox virus. We'll see a painless central open area nodule. A pox virus is endemic in sheep and goats. In humans, it's considered the ORF infection. It's usually self-limited and usually resolves in about six weeks, just like cat scratch disease. It's caused by Bartonella. You'll have swollen, tender lymphadenopathy and, again, typically management is symptomatic. If a patient does have some systemic symptoms, they may treat with antibiotics, but some of the separative lymph nodes weaken IND, but typically it's symptomatic treatment. Lyme disease, the most common tick-borne disease in North America. Early stage will be the skin lesions, the erythema migrans. As it progresses, it can develop into neurologic symptoms, cardiac symptoms in late stages, arthritis and sometimes encephalopathy. We'll initially use an ELISA test, if that's positive, in a Western blot. And it's Eremonis hydrophilia, is the bacteria that's involved with an infection that may occur when we use leeches. We also see a certain bacteria that occurs infections with catfish stings. The Eremonis is endosymbiotic with a leech and it actually provides the enzyme to break down the red blood cell for the leech. Treatment typically is early debridement of whatever infectious process, and we usually treat or even prophylaxe patients with leeches with Cipro. Prothochosis is a disease mostly of animals, but occasionally you'll see a human infection. It's a green algae, most common in the skin and bursa. Again, treatment, a bursectomy, antifungal medications. We do see infections with open dystereas fractures. Highest incidence in the more contaminated wounds and it does correlate with Gastilo's classification. And timing within the first 24 hours tends to be not affecting the ultimate treatment or ultimate results of an open dystereas fracture. So in summary, MRSA is now the most common form of staph, septic flexor tenosynovitis, just irrigation debridement in the mild stages is just as good as the IV catheter that we used to use. Be vigilant for deep space infections. And Mycobacterium marinum is the most common atypical mycobacterial infection. And beware of that initially benign, say, lytic process that could be associated with necrotizing fasciitis, which requires urgent incision drainage. Why don't we just stop there and go on to the next talk and keep up with time.

hand infections

common organisms

diagnostic techniques

treatment options

necrotizing fasciitis

proper management