MICP MIDTERMS: SKIN INFECTIONS

macule

flat lesions, change in color in the affected skin

papule

raised lesions, solid in consistency of less than 5 mm in diameter

plaque

flat with elevated surface (plateau-like) with more than 5 mm in diameter

nodules

rounded raised lesions with more than 5 mm in diameter

urticaria

annular or ring-like papules or plaques with pinkish color

vesicles

circumscribed fluid-filled lesions less than 5 mm in diameter

pustules

circumscribed, exudate-filled lesions

bullae

circumscribed fluid-filled lesions more than 5 mm in diameter

purpura

skin lesions due to bleeding into the skin

petechiae, purpura (skin lesions due to bleeding into the skin)

skin lesions due to bleeding into the skin, less than 3 mm in diameter

two answers

ecchymosis

skin lesions due to bleeding into the skin, more than 3 mm diameter

ulcer

crater-like lesion that may involve the deeper layers of the epidermis and dermis

eschar

necrotic ulcer covered with a blackened scab or crust

bacterial skin infection: staphylococcus aureus

common pathogen in humans, gram positive cocci usually arranged in pairs, short chains, but commonly in grape-like clusters

bacterial skin infection: staphylococcus aureus

it is found in the skin and nasopharynx. on culture they produce gray to golden yellow colonies. golden yellow colonies are best produced when cultured at 20-25*C

bacterial skin infection: staphylococcus aureus, coagulase

catalase (to differentiate it from streptococcus)

it is _____ positive, which differentiates it from other species of staphylococcus. it also produces enzymes and toxins responsible for its invasiveness and pathogenicity.

bacterial skin infection: staphylococcus aureus

mode of transmission: skin infections are transmitted through direct contact with a person having purulent lesions, from hands of healthcare or hospital workers, and through fomites like bed linens and contaminated clothing.

clinical findings of bacterial skin infection staphylococcus aureus: folliculitis

a pyogenic (pus producinh) infection involving the hair follicle. it is characterized by localized painful inflammation and heals rapidly after draining the pus.

clinical findings of bacterial skin infection staphylococcus aureus: furuncle

an extension of folliculitis and is also known as boil. it is characterized by larger and painful nodules with underlying collection of dead and necrotic tissue

clinical findings of bacterial skin infection staphylococcus aureus: carbuncle

represents a coalescence of furuncles that extends into the subcutaneous tissue with multiple sinus tracts

clinical findings of bacterial skin infection staphylococcus aures: sty or hordoleum

folliculitis occurring at the base of the eyelids

clinical findings of bacterial skin infection staphylococcus aureus: impetigo

infection is common in young children and primarily involves the face and limbs. initially, it starts as a flattened red spot (macule) which later becomes a pus-filled vesiccle that ruptures and forms crust (honey-colored crust). it may be caused by both S. aureus and S. pyogens

clinical findings of bacterial skin infection staphylococcus aureus: staphylococcal scalded skin syndrome (ritter’s disease), nikolsky, exfoliative toxin

primarily a dsz that is found in newborns and young children. it is manifested by sudden onset of perioral eryhthema (redness) thag covers the whole body within 2 days. when slight pressure is applied over the skin, it causes displacement of the skin. this is known as positive ________ sign. bullae and cutaneous blister formation will soon follow and and will later undergo desquamation. antibodies against the exfoliative toxin are produced within 7-10 days, enabling the skin to become intact again. the toxin responsible for these manifestations is the _________. only the outer layer of the epidermis is affected, hence there will be no scarring

laboratory diagnosis of bacterial skin infection staphylococcus aureus, gram-positive cocci, gray to golden yellow colonies

includes microscopic examination of gram stained specimen (________) and culture (____________). the organisms are catalase positive and coagulase positive

treatment and prevention of bacterial skin infection staphylococcus aureus, beta-lactam antibiotics, oxacillin

the treatment of choice is ________ such as penicillin. however, s aureus readily develop resistance to penicillin and other penicillin derivatives such as methicillin and nafcillin. ______ is the only penicillin derivative that has remained active against it. the incision and drainage of of localized skin and soft tissue infection is also necessary.

Staphylococcus Epidermidis

is part of the normal flora of the skin and is commonly associated with stitch abscess, UTI, and endocarditis. it also causes infecitons in individuals with prosthetic devices.

Streptococci: Streptococcus pyogenes, group A, lancefield classification, beta, M protein, phagocytosis

gram positive cocci arranged in pairs or in chains when seen under the microscope. it belongs to ________ streptococci based on _______. It is _____ hemolytic (complete hemolysis of blood). its major virulence factor is _____ which is anti phagocytic. they also produce enzymes and toxins responsible for the pathogenesis of infections caused by the organism. some strains are encapsulated which protect them from _______ and may be associated with severe systemic infections.

mode of transmission of Streptococcus pyogenes

some tissue infections are acquired through direct contact with infected persons or through fomites

pyoderma or impetigo, vesicles, pustules

clinical skin infection of streptococcus pyogenes: a purulent skin infection that is localized and commonly involves the face and the upper and lower extremities. It starts as _____ then progresses to _____. The lesions rupture and form honey-colored crusts. There may be enlargement of the regional lymph nodes but no sign of systemic infection.

caused by S. pyogenes, Erysipelas (St. Anthony's Fire)

follows a respiratory tract or skin infection caused by S. pyogenes. Patients manifest with localized raised areas associated with pain, erythema, and warmth. It is grossly distinct from normal skin. There is accompanying lymphadenopathy and systemic manifestations

caused by S. pyogenes, Cellulitis

involves the skin and subcutaneous tissue. Unlike erysipelas, the infected and the normal skin are not clearly differentiated. It is also manifested as local inflammation with systemic signs

caused by S. pyogenes, Necrotizing Fasciitis, streptococcal gangrene

involves the deep subcutaneous tissue and is also known as "flesh-eating" or_________. It starts as cellulitis then becomes bullous and gangrenous. It spreads to the fascia then the muscle and fat. It may become systemic and cause multi-organ failure leading to death.

skin and throat infections, S. pyogenes throat infection

Acute glomerulonephritis and rheumatic fever are non-suppurative, immune-mediated complications. Acute glomerulonephritis is associated with _________ while rheumatic fever is usually associated with _________.

gram-positive cocci in pairs and chains

lab diagnosis of streptococcus pyogenes: microscopy: Gram stain of samples of infected tissue will show _____________ associated with leukocytes

beta hemolysis

lab diagnosis of streptococcus pyogenes: culture: positive _______ in blood agar

positive (+) zone of inhibition growth

lab diagnosis of streptococcus pyogenes: bacitracin test: antiobiotic susceptibility test with ___________ around the bacitracin disc

Treatment and Prevention of streptococcus pyogenes

The drug of choice is penicillin. In case of penicillin allergy, macrolides (erythromycin, azithromycin) or cephalosporins are alternate drugs. The drainage of pus and thorough debridement of infected tissues must also be done.

Pseudomonas aeruginosa 

are gram-negative bacilli arranged in pairs that are encapsulated. They are capable of producing water-soluble pigments (e.g., pyocyanin - blue).

Pseudomonas aeruginosa 

It is an opportunistic pathogen, a common cause of nosocomial infections (hospital-acquired) and resistant to most antibiotics

Pseudomonas aeruginosa 

The virulence of _________ can be attributed to adhesins (flagella, pili, lipopolysaccharide, alginate), toxins (exotoxin A, pigments), and enzymes.

Mode of Transmission: Pseudomonas aeruginosa 

A common mode of transmission is through the colonization of previously injured skin. 

Pseudomonas aeruginosa

is commonly associated with colonization of burn wounds and characterized by blue-green pus that exudes a sweet grape-like odor. Other skin infections are folliculitis, and secondary infections in individuals with acne and nail infections resulting from immersion in contaminated water.

Pseudomonas aeruginosa, osteochondritis

It is also the most common cause of inflammation of the bone and cartilage of the foot called ________ following a penetrating injury.

Pseudomonas aeruginosa, Oxidase

Gram stain demonstrates gram-negative bacilli arranged individually or in pairs. Culture shows flat colonies with green pigmentation and characteristic sweet, grape-like odor. _______test is positive. 

Pseudomonas aeruginosa

is resistant to most antibiotics, hence culture and sensitivity must be done. Preventive measures for control of _______ should be focused on preventing contamination of sterile hospital equipments and instruments, and cross-contamination of patients by hospital personnel.

Clostridium perfringens 

are gram-positive bacilli that are anaerobic and rarely produce endospores.

Clostridium perfringens, alpha, beta, iota, and epsilon, alpha

It produces four lethal toxins namely: _________ toxins. Of the four toxins, ______ toxin is the most lethal because it acts as a lecithinase that cause lysis of erythrocytes, platelets, and leukocytes. This toxin also causes massive hemolysis and bleeding and tissue destruction. It is widely distributed in nature and particularly associated with soil and water contaminated with feces.

Clostridium perfringens 

is commonly transmitted by the colonization of the skin following physical trauma or surgery. 

Clostridium perfringens 

causes soft tissue infections such as cellulitis, suppurative myositis, and myonecrosis or gas gangrene

Gas gangrene (Clostridium perfringens)

is a life-threatening infection following physical trauma or surgery characterized by massive tissue necrosis with gas formation, shock, renal failure, and death within 2 days of onset.

state what bacteria causes this

Laboratory Diagnosis of Clostridium perfringens 

Diagnosis is based on microscopic detection of gram-positive bacilli in pairs and growth in culture under anaerobic condition.

Treatment and Prevention of Clostridium perfringens, high-dose penicillin therapy

Surgical wound debridement and ______ are the main approaches to the management of the disease.

Bacillus anthracis 

 are gram-positive bacilli arranged individually or in pairs or long serpentine chains giving them the characteristic "bamboo fishing rod" or "Medusa head" appearance.

Bacillus anthracis, polypeptide capsule

It is aerobic, spore-forming, and encapsulated. Virulence of the organism is due to its _______ which is responsible for evading phagocytosis and toxins-edema toxin and lethal toxin-both of which inhibit the host's immune responses.

Bacillus anthracis

can also be used in bioterrorism

B. anthracis mode of transmission

is transmitted through inoculation into open skin from either the soil or infected animal products, ingestion of infected meat or milk, and inhalation of aerosolized spores.

Bacillus anthracis clinical findings, cutaneous anthrax

_________ is a disease of herbivores. There are three forms: cutaneous gastrointestinal, or pulmonary. The skin infection, ________ , is the most common form

anthrax (Bacillus anthracis)

 It is characterized by painless papules at the site of inoculation that become ulcerative, and later develops necrotic eschar. This is also associated with painful lymphadenopathy and edema

peripheral, carbon dioxide, Dorner stain or Wirtz-Conklin

The ______ blood contains a large number of B. anthracis which is easily seen on Gram stain. Spores are only observed on culture in low ________ tension. Demonstration of the spores can be done using _________ stain

Treatment and Prevention of Bacillus anthracis, ciprofloxacin

Antibiotics such as penicillin or doxycycline are the drugs of choice. In resistant cases, _____ is recommended. Prevention is through vaccination of animals and individuals at risk such as animal handlers, veterinarians, military personnel, and those working in slaughterhouses.

Superficial Mycoses: Tinea versicolor (Pityriasis versicolor), sebaceous glands, tropical regions.

 is caused by Malassezia furfur (formerly known as Pityrosporum orbiculare). M. furfur is a normal flora of the skin particularly in areas rich in _________. The infection is worldwide in distribution but more common in ________. The lesions are irregular, discrete hypo- or hyperpigmented macules depending on the skin color of the affected individual. 

Superficial Mycoses: Tinea versicolor (Pityriasis versicolor),

The lesions are scaly, with a dry, chalky appearance and usually appear on the face, neck trunk, and arms.

Superficial Mycoses: Tinea versicolor (Pityriasis versicolor), M. furfur

Diagnosis is made by microscopic visualization of "spaghetti and meatballs" appearance of _____ with an alkaline stain (10% KOH or NaOH). It can also be demonstrated with periodic acid-Schiff stain (PAS stain) or hematoxyllin-eosin stain (H & E stain).

Superficial Mycoses: Tinea versicolor (Pityriasis versicolor), M. furfur

Treatment includes application of keratolytic agents containing selenium disulfide or salicylic acid and topical antifungal drugs such as ketoconazole. 

Superficial Mycoses: Tinea Nigra

is caused by Hortaea werneckii (formerly known as Exophiala werneckii), a dematiaceous fungus that produces melanin and grows as mold producing annelids or annelloconidia

Superficial Mycoses: Tinea Nigra

The lesions involve the palms and soles and are described as gray to black, well-demarcated macules. The infection is common in the tropical and subtropical regions, and is more frequently seen in adolescents, young adults, and females.

Superficial Mycoses: Tinea Nigra, potassium hydroxide, Sabouraud dextrose agar

Diagnosis is made by direct microscopic examination of skin scrapings with _______ and culture using _________ medium. Treatment is similar to the treatment for tinea versicolor

Cutaneous Mycoses, dermatophytes

are fungal infections involving the keratinized structures of the body such as the skin, hair, and nails. The infection is caused by a group of fungi collectively referred to as _______.

Cutaneous Mycoses: Dermatophytes, keratinophilic, keratinolytic

produce keratinase, an enzyme capable of breaking down keratin. They are ______ (organisms, particularly fungi, that prefer or thrive in keratin-rich environments) and ______ (Organisms that actively degrade and digest keratin using keratinase enzymes)

Cutaneous Mycoses or Dermatophytosis: Microsporum, Trichophyton, Epidermophyton

The three genera that cause these infections are: (1) ______ which infect the hair and nails only; (2) _______ which infect the skin, hair, and nails, and (3) _________ which infect only the skin and nails. 

both microconidia and macroconidia, microconidia, macroconidia

zoophile, geophilic, anthropophilic

Microsporum produces _______ with predominance of macroconidia, while Trichophyton predominantly produces ________. Epidermophyton, on the other hand, produces smooth-walled _______ in bundles of two or three. Based on their natural habitat, dermatophytes are classified as _______ (from animals to humans), _______ (from the soil to humans or animals), and ______ (from humans to humans).

tinea, tinea pedis, tinea capitis, tinea corporis, tinea cruris or jock itch, tinea manus, tinea barbae, tinea unguium

In cutaneous mycoses, The infections are referred to as ____ or ringworm. The name of the infection reflects the anatomic site involved, namely: (1) ______, also known as athlete's foot (feet); (2) _______ (scalp); (3) ________ (body); (4) _______ (groin); (5) _____ (hands); (6) ______ (beard); and (7) _________, also known as onychomycosis (nails). 

ring worm, ectothrix, endothrix, favic

Tinea involving the skin usually presents with a "_________" pattern. The lesions have reddish border with central clearing. There may be inflammatory scaling. Hair invasion can be ________ (arthroconidia are outside the hair shaft), ______ (arthroconidia are inside the hair shaft), or _____ (formed inside the hair but with "honeycomb" pattern or resembling a favic chandelier) depending on the dermatophyte species causing the infection.

Laboratory Diagnosis of Cutaneous Mycoses or Dermatophytosis

Specimens for diagnosis are skin or nail scrapings, or hair cuttings from the affected areas. More fungi can be obtained from the borders of the lesion rather than the center. Diagnosis is based on the clinical appearance of the lesions, direct microscopis examination and culture. 

Subcutaneous Mycoses 

The infection initially involves the deeper layers of the dermis and subcutaneous tissue then later the bones.

Subcutaneous Mycoses

The mode of transmission is through traumatic inoculation into the skin

Subcutaneous Mycoses 

 The infections are relatively rare with the exception of sporotrichosis. Other infections are chromoblastomycosis, phaeohyphomycosis, zygomycosis, and mycetoma (Madura Foot).

Subcutaneous Mycoses: rose gardener's disease, Sporothrix schenckii, small nodule, subcutaneous nodules, malignancy

Sporotrichosis, also known as ________, is caused by a dimorphic fungus, ______, which is found in the soil and decaying vegetation. The infection initially presents as a _____ which may later become ulcerative and pustular. Two weeks later, painless, _______ along the lymphatic drainage develops. Sometimes they may present as verrucous lesions and often misdiagnosed as ______ of the skin. 

Subcutaneous Mycoses: Chromoblastomycosis

is characterized by verrucous nodules or plaques

Subcutaneous Mycoses: Chromoblastomycosis

The infection is insidious and may become chronic. The etiologic agents are all dematiaceous fungi namely: Exophiala, Fonseca, Cladosporium, Phialophora, and Rhinocladiella. 

Subcutaneous Mycoses: Mycetoma or Madura foot, eumycotic, actinomycotic, feet and hands, characteristics of the granules. 

may be caused by true fungi (_________ mycetoma) or actinomycetes (______ mycetoma). The common causes of eumycotic mycetoma are Phaeoacremonium, Madurella, Curvularia, and Fusarium. It frequently involves the _______ . The infection is characterized by the clinical triad of tumefaction, granules, and draining sinus. Diagnosis is primarily based on the ________.

Viral Infections of the Skin: Warts, human papillomavirus (Family Papovavirila), 70

_____ are caused by a DNA virus, the ___________. There are at least ___ serotypes. The virus is capable of causing malignant transformation of the infected cell. 

HPV virus (Viral Infections of the Skin: Warts)

is acquired by (1) direct contact through mucosal or skin breaks (2) sexual contact; and (3) upon passage through infected birth canal.

Skin warts (common, plantar, and flat warts), 1-4, hands and feet ((Viral Infections of the Skin: Warts)

benign, self-limiting proliferation of the skin that undergoes spontaneous resolution. These warts may be flat, dome shaped, or plantar. 

HPV types ____ are the most common isolates from the lesions. Frequent affected sites are the _____ and common among children and adolescents 

Genital and anogenital warts

also known as condylomata acuminata (singular condyloma acuminatum

Laboratory Diagnosis of WARTS

Diagnosis is based on gross appearance of the lesions and histologic appearance on microscopic examination that includes hyperkeratosis. 

Treatment and Prevention  of WARTS

Treatment is removal of the lesion by: (1) surgical excision; (2) cryosurgery; (3) electrocautery; (4) application of caustic agents such as podophyllin; and (5) interferon for genital warts. Avoiding contact with infected tissue prevents spread of the infection.

Etiologic Agent (Herpes Simplex Infections)

herpes simplex virus (HSV) types 1 and 2, DNA viruses under the family of human Herpesviridae. These viruses are capable of latency in the neurons and are capable of recurrent infections.

Modes of Transmission ((Herpes Simplex Infections)

is present in oral and genital secretions and vesicle fluid. It can be transmitted through (1) oral contact (kissing); (2) fomites (sharing of glasses, toothbrushes, and other saliva-contaminated materials); (3) sexual contact; (4) transplacental (during pregnancy); and (5) during childbirth. 

Gingivostomatitis, gingivitis

the primary infection, primarily caused by HSV-1. It presents as vesicles that rupture and ulcerate. Lesions are seen in the buccal mucosa, palate, gingivae, pharynx, and the tongue. The most striking feature is _____. It is common during childhood. 

Herpes labialis (Fever Blister or Cold Sore)

represents recurrent mucocutaneous HSV infection. This is caused by HSV-1 and HSV-2. Lesions are usually located at the vermillion borders of the lips. Lesions are vesicular, they rupture then form an ulcer and later form crusts. Recurrences are less severe than the primary infection and often occur on the same site. 

Herpetic whitlow

HSV infection involving the fingers and caused by both HSV types 1 and 2. 

Eczema herpeticum

HSV infection occurring in children with eczema. This only shows that HSV can be an opportunistic pathogen. It can also cause a superimposed infection in burns.

Herpes gladiatorum

HSV infection of the body and is usually acquired during wrestling or playing rugby.

Laboratory Diagnosis (Herpes Simplex Infections)

Tzanck, Cowdry type A inclusions

Diagnosis is based mainly on the clinical presentation of the infection. Diagnosis can be made based on histopathologic changes and using the _______ smear to demonstrate the characteristic inclusion bodies known as the _______. Cell culture is also diagnostic but seldom requested. 

Treatment and Prevention of Herpes Simplex Infections

The recommended drug is acyclovir. There is currently no available vaccine for this.