BACTERIAL SKIN INFECTIONS

1. BACTERIAL SKIN INFECTIONS Yeditepe University School Of Medicine Dermatology Department MD. Ozlem Akın

2. Folliculitis • Bacterial skin infection of the hair follicles • Thin-walled pustules at the follicle orifices • S. aureus is the most frequent cause • Infection may secondarily arise in scratches, insect bites, or other skin injuries • Favorite locations extremities, scalp, face, eyelashes, axillae, pubis and thighs

4. Folliculitis • Treatment • Cleansing of the affected areas with antibacterial soap and water three times daily • Mupirocin ointment topically • If it fails a first generation cephalosporin, or a penicillinase resistant penicillin (oxacillin, cloxacillin, or dicloxacillin)

5. Furuncle • infection of the pilosebaceous unit, therefore is more extensive than a folliculitis because the infection also involves the sebaceous gland • frequently occurs on the neck, face, armpits, and buttocks • begins as a small, tender, red nodule that becomes painful and fluctuant. Frequently, pus will spontaneously drain, and often the furuncle will resolve on its own

7. Furuncle • Predisposing factors: • Obesity • Alcoholism • Malnutrition • Disorders of neutrophil function • Blood disorders • Iatrogenic or other immunosuppression, including AIDS • Diabetes • Atopic dermatitis • Irritation • Pressure • Friction • Hyperhidrosis • Shaving

8. Furuncle • Treatment: • Warm compressess • Incision and drainage (when the furuncle has become localized and shows definite fluctuation) • Penicillinase-resistant penicillin or a first generation cephalosporin 1-2 g/day • Methicillin-resistant and even vancomycin resistant strains occur. In unresponsive patients antibiotic resistant strains should be suspected and sensitivities should be checked. • Mupirocin cream to anterior nares daily for 5 days

9. Carbuncle • collection of multiple infected haif follicles • an abscess, just like a furuncle, but a much more serious infection • Whereas a furuncle is an infection of a hair follicle and the surrounding tissue, a carbuncle is actually several furuncles that are densely packed together. • usually extends into the deeper layers of the skin - the subcutaneous fat • forms into a broad, red, hot, painful nodule that often drains pus through multiple openings of the skin • Someone who has a carbuncle likely will feel sick and have a fever and fatigue • tend to occur in areas with thicker skin like the nape of the neck, the back, or the thighs

14. Carbuncle • Diagnosis • diagnosed based on their typical appearance, but sometimes they can be confused with a ruptured epidermoid cyst • There aren't any tests that are performed to decide if an infection is a carbuncle, but often the pus inside the carbuncle is tested with a gram stain or bacterial culture to determine if the bacteria causing the infection is a typical Staphylococcus aureus or one that is resistant to the usual penicillin-type antibiotics

15. Carbuncle • Because usually contain a significant amount of pus, they are usually first treated with a procedure called incision and drainage draining the pus and allowing the infection to heal from the inside out. • Carbuncles are typically caused by the bacteria, Staphylococcus aureus. The usual medications used to treat Staph infections include the antibiotics dicloxacillin or cephalexin. • Unfortunately, there is a new strain of Staph bacteria that is resistent to these antibiotics.

16. Carbuncles Caused by Methacillin Resistant Staphylococcus Aureus (MRSA) • In the past several years, there has been a sharp increase in the incidence of infections caused by a special strain of S. aureus that is resistant to the normal penicillin-based treatment. • Until recently, MRSA was an uncommon bacterial strain that occurred in nursing homes and other long-term care facilities. But with the overuse of antibiotics for conditions that don't require antibiotics, MRSA infections are common • These infections often occur spontaneously in the groin, buttock, and upper thigh region. Currently, there are antibiotics that do treat this resistant strain. The antibiotic of choice for MRSA infections that were not acquired from a hospital or long-term care facility is trimethoprim-sulfamethoxazole. The next option is clindamycin, especially for people who are allergic to sulfa.

17. Cellulitis • bacterial infection of the deeper layers of the skin, the dermis and the subcutaneous tissue. • In adults and children, most often caused by Streptococcus and Staphylococcus Aureus • Sometimes Haemophilus influenzae type B can cause cellulitis in children younger than 3, but this has become less common since we've been vaccinating against this bacteria. • Knowing the type of bacteria that commonly cause cellulitis helps doctors determine the best antibiotic to treat the infection.

18. Cellulitis • Bacteria are able to cause an infection if they can get into the skin through a break in the skin barrier (cuts, scrapes, ulcers, and surgical wounds) • Unfortunately, can also develop in skin that appears perfectly normal • Repeated infections often happen in areas where there is damage to the blood or lymph vessels that circulate fluid throughout the body. This damage can be caused by prior cellulitis infections, surgical removal of lymph nodes, removal of veins for vein grafts somewhere else in the body, and radiation to the area.

19. Cellulitis • Before skin changes occur, someone with cellulitis can have fever, chills, and fatigue. • The skin infection is usually red, swollen, warm to touch, and painful. • It's often difficult to tell exactly where the border is between normal and infected skin. • Red streaks coming out of the area and swollen lymph nodes can sometimes occur. • Children often get cellulitis on the head and neck, and adults often get cellulitis on the arms or legs.

20. Cellulitis • Diagnosis • usually diagnosed based on its typical appearance. • blood count • blood cultures • A cellulitis infection doesn't have pus that could be cultured to see what bacteria are involved. • Sometimes a doctor might do an "aspirate" which involves injecting sterile fluid into the infected tissue and drawing it back out, hoping that some of the bacteria get washed into the fluid. This fluid is then cultured to see what bacteria grow. • An aspirate is usually done in unusual situations where there is a high chance that the infection is caused by a different bacteria than expected.

21. Cellulitis • Treatment • Most infections require 10 days of an oral antibiotic. If the infection is on an arm or especially a leg, elevating the extremity often speeds healing. • IV antibiotics might be used in more severe cases such as: • Cellulitis of the face • Someone who is seriously ill • Infections in people who are immunocompromised • Infections that didn't improve or got worse with oral antibiotics

22. Cellulitis • Prevention • The best prevention is taking good care of any break in the skin. This can be done by: • Washing the wound daily with soap and water • Applying a topical antibiotic to the wound • Keeping it covered with a bandage to keep it clean • Changing the bandage every day or more often if the bandage gets dirty or wet

23. Erysipelas • a superficial infection of the skin, which typically involves the lymphatic system • most often caused by Group A Streptococcus • In a few cases, it can be caused by other types of Streptococcus or Staphylococcus bacteria • Some cases of erysipelas have an inciting wound such as trauma, an abrasion, or some other break in the skin that precede the fiery infection • However, in most cases, no break in the skin can be found

24. Erysipelas • was previously found mainly on the face • However, now it is seen most commonly on the lower extremities • tends to occur in areas where the lymphatic system is obstructed • A cluster of symptoms (fever, chills, fatigue, anorexia, and vomiting) typically precede the appearance of the rash by 4 to 48 hours • The rash then quickly appears as a bright red, hot, swollen, shiny patch that has clearly defined borders • The consistency of the rash is similar to an orange peel, also known as "peau d'orange"

26. Erysipelas • Diagnosis • mainly by the appearance of the rash • Blood tests and skin biopsies generally do not help make the diagnosis • In the past, saline solution was injected into the edge of the rash, aspirated back out, and cultured for bacteria. This method of diagnosis is not used anymore because bacteria were not found in the majority of cases • If the preceding symptoms such as fever and fatigue are significant enough, sometimes blood is drawn and cultured for bacteria to rule out sepsis.

27. Erysipelas • Treatment • A variety of antibiotics can be used including penicillin, dicloxacillin, cephalosporins, clindamycin, and erythromycin • Most cases can be treated with oral antibiotics • However, cases of sepsis, or infections that do not improve with oral antibiotics require IV antibiotics administered in the hospital.

28. Erysipelas • Recurrence of Erysipelas • Even after appropriate treatment with antibiotics, can recur in 18% to 30% of cases • People who are susceptible to recurrence are those with compromised immune systems or compromised lymphatic systems • Because erysipelas can damage the lymphatic system, the infection itself can be a setup for recurrence • Some people with recurrent infections must be treated daily with low-dose antibiotics as a prevention of further infections.

29. Impetigo • a common bacterial infection of the upper layers of the skin caused by Streptococcus pyogenes and Staphylococcus aureus • highly contagious and usually treated with a topical antibiotic • In industrialized countries most cases are caused by Staphylococcus aureus, but in developing countries Streptococcus pyogenes is the main causitive agent. • Mixed infections caused by both bacteria are common

30. Impetigo • tends to occur in areas of minor breaks in the skin such as insect bites, cuts, or abrasions • can also occur in breaks in the skin caused by skin conditions such as eczema, scabies, herpes, chickenpox, pediculosis capitis or contact dermatitis

31. Impetigo • common contributing factors: • Warm, humid climate or environment • Traumatized skin • Poor hygiene • Overcrowding • Nasal colonization with bacteria

32. Impetigo • Clinical findings • classified as bullous or non-bullous • both types have a distinct appearance and cause

33. Impetigo • Non-Bullous Impetigo • More common - 70% of impetigo infections • Caused by either Streptococcus or Staphylococcus species • Hallmark of appearance is a thick "honey-colored" crust • Occurs mainly on face or limbs • Only large lesions are painful • Generally does not cause a fever • Heals without scarring

35. Impetigo • Bullous Impetigo • Less common form of impetigo • Occurs mainly in newborns and younger children • Caused by a specific sub-group of Staphylococcus aureus • Blisters form in response to a toxin produced by the bacteria • Occurs on face, trunk, hands, and buttocks • Generally does not cause a fever • Heals without scarring

37. Impetigo • Diagnosis • often diagnosed clinically, based on the characteristic appearance. • Gram stain • Bacterial culture

38. Erythrasma • caused by Corynebacterium minutissimum • occurs most often between the third and fourth toes, but also frequently can be found in the groin, armpits, and under the breasts • more common in the following populations: • Overweight people • Elderly • Diabetics • People in warm, moist climates

39. Erythrasma • Clinical findings • starts as a pink to red patch with well-defined edges • patch has a finely wrinkled appearance with a very fine scale on it • after some time, the rash fades from pink to a uniform brown color (ddx from fungal infections)

41. Erythrasma • Differential diagnosis: • Inverse psoriasis • Tinea cruris • Intertrigo • Seborrheic dermatitis • Candidiasis • Tinea versicolor • Lichen simplex chronicus

42. Erythrasma • Diagnosis • Wood's Lamp examination: under the UV light of a Woods Lamp, erythrasma turns a bright coral red, but fungal infections do not. • Gram Stain: Unfortunately, this bacteria is difficult to get to stick to the slide so it requires a special technique. • KOH Test: to confirm that there is no fungus present • Skin Biopsy

45. Erythrasma • Treatment • Erythromycin 250 mg four times a day for 5 days • Clarithromycin 1gm once • The antifungal creams (clotrimazole) • Topical antibiotics like clindamycin or erythromycin twice a day for 2 weeks