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