Lecture 2: Bacterial Infections of the Skin - Alkafeel University

Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two Bacterial infections of the skin The human body is covered in skin. One of its primary purposes is to prevent microbes in the surrounding environment from invading underlyin...

Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two Bacterial infections of the skin The human body is covered in skin. One of its primary purposes is to prevent microbes in the surrounding environment from invading underlying tissues and organs. But in spite of its role as a protective covering, skin is not itself immune from infection. Certain pathogens and toxins can cause severe infections or reactions when ‫تنتهز لفرصه‬ they come in contact with the skin. Other pathogens are " ‫اختراق الجلد الطبيعية‬ opportunistic, breaching the skin‟s natural defenses through cuts, wounds, or a disruption of normal microbiota resulting in an infection in the surrounding skin and tissue. Still other pathogens enter the body via different routes (through the respiratory or digestive systems) but cause reactions that manifest as skin rashes or lesions. Layers of the Skin (epidermis, dermic hypodermis) Normal Microbiota of the Skin for example: 1. Staphylococcus epidermidis 2. Staphylococcus aureus 3. Alpha hemolytic and non-hemolytic streptococcus 4. Micrococcus spp 5. Peptostreptococcus spp 6. Neisseria spp 7. Propionibacterium spp 8. Diphtheroids 9. Candida spp 10.Acinetobacter spp Medical Terms Associated with Skin Lesions and Rashes 1. Abscess localized collection of pus ‫بثرة‬ 2. Bulla (pl., bullae) fluid-filled blister no more than 5 mm in diameter 3. Carbuncle deep, pus-filled abscess generally formed from multiple furuncles ‫السوائل املجففة‬ 4. Crust dried fluids from a lesion on the surface of the skin 5. Cyst encapsulated sac filled with fluid, semi-solid matter, or gas, typically 6. Located just below the upper layers of skin 7. Folliculitis a localized rash due to inflammation of hair follicles 8. Furuncle (boil) pus-filled abscess due to infection of a hair follicle 9. Macules smooth spots of discoloration on the skin 10.Papules small raised bumps on the skin 11.Pseudocyst lesion that resembles a cyst but with a less defined boundary 12.Purulent pus-producing; suppurative 13.Pustules fluid- or pus-filled bumps on the skin 14.Pyoderma any suppurative (pus-producing) infection of the skin 15.Suppurative producing pus; purulent 16.Ulcer break in the skin; open sore 1 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two 17.Vesicle small, fluid-filled lesion 18.Wheal swollen, inflamed skin that itches or burns, such as from an insect bite Staphylococcal Infections The Staphylococcus genus includes at least 30 species. Most are harmless and reside normally on the skin and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora. Several species can cause a wide variety of infections in humans and other animals through infection or the production of toxins. The most common type is S.aureus. Cell morphology Staphylococci are gram positive spherical cocci, (0.8µm–1.0µm in diameter).‫عناقيد مثل العنب‬ arranged characteristically in grape like clusters. They are non-motile and non- spore forming and few strains are capsulated. They are aerobes and facultative anaerobe, optimal temperature is 37°C and optimum pH is 7.4–7.6. They have several unique properties: Virulence Factors 1. Peptidoglycan: It is a polysaccharide polymer. It activates complement and induces the release of inflammatory cytokines 2. Teichoic acid: it facilitates adhesion of cocci to the host cell surface. 3. Protein A: It is chemotactic, antiphagocytic, anticomplementary and induce platelet injury. Toxins: 1. Hemolysins: It is an exotoxin, those lysis red blood cells. They are of four types namely α-lysin, β-lysin, γ-lysin and delta lysin. 2. Leucocidin: It damages PMNL (polymorphonuclear leucocytes) and macrophages. ‫مظهر‬ 3. Enterotoxin: It is responsible for manifestations of Staphylococcus food poisoning. 4. Exfoliative toxin: This toxin causes epidermal splitting resulting in blistering diseases. 5. Toxic shock syndrome toxin: TSST is responsible for toxic shock syndrome. Enzymes: 1. Coagulase: It clots human plasma and converts fibrinogen into fibrin. 2. Staphylokinase: It has fibrinolytic activity. 3. Hyaluronidase: It hydrolyzes hyaluronic acid of connective tissue, thus facilitates the spread of the pathogens to adjacent cells. 4. Other enzymes : lipase, nucleases and proteases Laboratory environment 1. Sampling: skin lesion and wounds 2  Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two 2. Microscopically, gram-positive Staphylococcus species have cellular arrangements that form grapelike clusters. 3. Macroscopically, when grown on blood agar, colonies have a unique pigmentation ranging from opaque white to cream. 4. Biochemically:  Catalase test: The genus Staphylococci are catalase positive ((H2O2 H2O+O2). This test distinguishes Staphylococcus from Streptococcus (catalase negative)  Coagulase test: This test helps in differentiating a pathogenic strain from non-pathogenic strain. S. aureus is coagulase positive. Clinical demonstration Staphylococcus species are commonly found on the skin, with S. epidermidis and S. hominis being prevalent in the normal microbiota. S. aureus‫للعدوى‬ is ‫ناقل‬ also commonly found in the nasal passages and on healthy skin. S. aureus is quite contagious. It is spread easily through skin-to-skin contact, and because many people are chronic nasal carriers, the bacteria can easily be transferred from the nose to the hands and then to fomites or other individuals. 1. Superficial Staphylococcal Infections S. aureus is often associated with pyoderma (purulent). Pus formation occurs because many strains of S.aureus produce leukocidins, which kill white blood cells. These purulent skin infections may initially manifest as folliculitis, but can lead to furuncles or deeper abscesses called carbuncles.  Folliculitis (furuncles and carbuncles) Folliculitis generally presents as bumps and pimples that may be itchy, red, and/or pus-filled. In some cases, folliculitis is self-limiting, but if it continues for more than a few days, worsens, or returns repeatedly, it may require medical treatment. Sweat, skin injuries, ingrown hairs, tight clothing, irritation from shaving, and skin conditions can all contribute to folliculitis.  Furuncles (boils) are deeper infections. They are most common in young adults and teenagers, who play contact sports, share athletic equipment, have poor nutrition, live in close quarters, or have weakened immune systems. Good hygiene and skin care can often help to prevent furuncles from becoming more infective, and they generally resolve on their own.  Carbuncle is a multiple boils develop into a deeper lesion. Because carbuncles are deeper, they are more commonly associated with systemic symptoms and a general feeling of illness. Larger, recurrent, or worsening carbuncles require medical treatment, as do those associated with signs of illness such as fever. Carbuncles generally need to be drained and treated with antibiotics.  Staphylococcal scalded skin syndrome (SSSS) 3 Carbuncle Furuncles Folliculitis pyoderma (purulent).  Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two SSSS Impetigo Bacterial exotoxins first produce erythema (redness of the skin) and then severe peeling of the skin, as might occur after scalding. SSSS is diagnosed by examining ‫كما قد يحدث بعد الحروق‬ characteristics of the skin (which may rub off easily), using blood tests to check for elevated white blood cell counts, culturing, and other methods. Intravenous antibiotics and fluid therapy are used as treatment. 2. Impetigo ‫الحصف داء جلدي يصيب األطفال‬ The skin infection impetigo causes the formation of vesicles, pustules, and possibly bullae, often around the nose and mouth. Bullae are large, fluid-filled blisters that measure at least 5 mm in diameter. Impetigo can be diagnosed as either nonbullous or bullous. In nonbullous impetigo, vesicles and pustules rupture and become encrusted sores. Typically the crust is yellowish, often with exudate draining from the base of the lesion. In bullous impetigo, the bullae fill and rupture, resulting in larger, draining, encrusted lesions. Impetigo can be caused by S.aureus alone, by Streptococcus pyogenes alone, or by coinfection of S. aureus and S. pyogenes. Impetigo is often diagnosed through observation of its characteristic appearance. Topical or oral antibiotic treatment is typically effective.‫مستشفى‬ 3. Nosocomial S. epidermidis Infections S. epidermidis is usually a harmless resident of the normal skin microbiota. Health- care workers can inadvertently transfer S. epidermidis to medical devices that are inserted into the body, such as catheters, prostheses, and indwelling medical devices. Once it has bypassed the skin barrier, S. epidermidis can cause infections inside the body that can be difficult to treat. To reduce the risk of nosocomial (hospital-acquired) S. epidermidis, health-care workers must follow strict procedures for handling and sterilizing medical devices before and during surgical procedures. Streptococcal Infections Cell morphology The genus Streptococcus is a facultative, gram-positive anaerobe, 0.5 to 1.2 μm in‫العدوى‬ diameter and arranged in pairs or chains, the streptococci commonly encountered in infections in humans include S. pyogenes, S. agalactiae, S. pneumoniae, E. faecalis,E. faecium,. The most clinically important streptococcal species in humans is S.pyogenes, also known as group A streptococcus (GAS). The streptococci are differentiated based ‫اختياري‬ on: 1. Oxygen requirements (aerobic, facultative anaerobes, obligatory anaerobes) 2. Brown classification, Hemolytic patterns on sheep blood agar (beta, alpha, or gamma) 3. Lancefield Classification based on the distinguishing characteristics of their surface carbohydrates (A, B, C, D). 4  Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two 4. Sherman‟s classification, physiologic characteristics (pyogenic , lactococci, enterococci, viridans ). 5. Biochemical classification ( sugar fermentation, production of enzymes, AST, colony formation, hemolysis patterns) S. pyogenes produces a variety of extracellular enzymes, including: Enzymes that can aid in transmission and contribute to the inflammatory response:  streptolysins O and S  hyaluronidase  streptokinase  proteases ‫مثير‬ Virulence factors help the bacteria to avoid phagocytosis while provoking a substantial immune response that contributes to symptoms associated with streptococcal infections:  Capsule and M protein, a streptococcal cell wall protein. Laboratory environment 1. Sampling: swab from infected skin lesion 2. Microscopically, S. pyogenes appears as Gram-positive Cocci, arranged in chains 3. Macroscopically Colonies are typically small (1–2 mm in diameter), translucent, entire edge, with a slightly raised elevation that can be either non- hemolytic, alpha hemolytic, or beta-hemolytic when grown on blood agar. 4. Biochemically: the S.pyogenes are catalase negative, non-motile. Clinical demonstration 1. Cellulitis is an infection that develops in the dermis or hypodermis, which presents as a reddened area of the skin that is warm to the touch and painful. 2. Erysipelas, a condition that presents as a large, intensely inflamed patch of skin involving the dermis (often on the legs or face) 3. Erythema nodosum, characterized by inflammation in the subcutaneous fat cells of the hypodermis. Many immunological tests, including agglutination reactionsand ELISAs, can be used to detect streptococci. Penicillin is commonly prescribed for treatment of cellulitis and erysipelas because resistance is not widespread in streptococci at this time. In most patients, erythema nodosum is self-limiting and is not treated with antimicrobial drugs. Recommended treatments may include nonsteroidal anti-inflammatory drugs (NSAIDs), cool wet compresses, elevation, and bed rest. 4. Necrotizing Fasciitis Necrotizing fasciitis is a rapidly progressive inflammatory infection of the fascia, with secondary necrosis of the subcutaneous tissues. The speed of spread is 5 Necrotizing Fasciitis Cellulitis Erysipelas Erythema nodosum Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two directly proportional to the thickness of the subcutaneous layer. Necrotizing fasciitis moves along the facial plane. Streptococcal infections that start in the skin can sometimes spread elsewhere, resulting in a rare but potentially life-threatening condition called necrotizing fasciitis, sometimes referred to as flesh-eating bacterial syndrome. S. pyogenes is one of several species that can cause this rare but potentially-fatal condition; others include Klebsiella pneumonia, Clostridium (type III), Escherichia coli, S. aureus, and Aeromonas hydrophila. Bacterial proteases unique to S. pyogenes aggressively infiltrate and destroy host tissues, inactivate complement, and prevent neutrophil migration to the site of infection. The infection and resulting tissue death can spread very rapidly, as large areas of skin become detached and die. Treatment generally requires debridement (surgical removal of dead or infected tissue) or amputation of infected limbs to stop the spread of the infection; surgical treatment is supplemented with intravenous antibiotics and other therapies. Pseudomonas Infections‫بيئات‬ The bacteria distributed throughout different habitats in the world. The species name „aeruginosa„ is derived from the Latin term „aeruginosa‟ meaning full of copper rust or verdigris (green) indicating its fluorescence. One of the important classifications of Pseudomonas is based on the production of pigments and fluorescence. P. aeruginosa belongs to the fluorescent group of Pseudomonas species. P. aeruginosa commonly found in water and soil as well as on human skin. Cell morphology Pseudomonas aeruginosa is an aerobic microorganism that is a motile, aerobic, Gram-negative rod-shaped oxidase-positive, with a single flagellum inserted at the tip of the cell. The flagella yield heat-labile antigens (H antigens) acting as a virulence factor in pathogenic strains. Besides flagella, polar fimbriae or pili are also found in some strains of P. aeruginosa. These pili are usually 6 nm wide and act as a receptor for various phages and are even retractile. Laboratory environment 1. Sampling: infected skin(pus, drains) 2. Microscopically: The presence of Gram-negative rods on microscopic observation provides a piece of preliminary information on the diagnosis. 3. Macroscopically: It has a simple nutritional requirement and can grow in media containing acetate as a source of carbon and ammonium sulfate as the source of nitrogen.P. aeruginosa can be detected through the use of cetrimide agar, which is selective for Pseudomonas species. The growth is best observed at 37°C, but the growth can be observed at a temperature as high as 42°C.The colonies on different media help distinguish the organism from other similar 6 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two organisms. An important characteristic of P. aeruginosa is the production of fluorescein, which can be detected via visual examination under UV light. 4. Biochemically: catalase positive, oxidase positive, indole negative Clinical demonstration Wounds infected with P. aeruginosa have a distinctive odor resembling grape soda or fresh corn tortillas. This odor is caused by the 2-aminoacetophenone that is used by P. aeruginosa in quorum sensing and contributes to its pathogenicity. P. aeruginosa have virulence factors: 1. Blue-green pus due to the pigments pyocyanin and pyoverdin(siderophores that help P. aeruginosa survive in low-iron environments by enhancing iron uptake). 2. phospholipase C (a hemolysin capable of breaking down red blood cells), 3. exoenzyme S(involved in adherence to epithelial cells), 4. Exotoxin A (capable of causing tissue necrosis). 5. Slime that allows the bacterium to avoid being phagocytized 6. Fimbriae for adherence 7. Proteases that cause tissue damage. P. aeruginosa is a common cause of: 1. Opportunistic infections of wounds and burns 2. Hot tub rash, a condition characterized by folliculitis that frequently afflicts users of pools and hot tubs 3. Otitis externa (swimmer‟s ear), an infection of the ear canal that causes itching, redness, and discomfort, and can progress to fever, pain, and swelling Pseudomonas spp. tend to be resistant to most antibiotics (β-lactamases), Polymyxin B and gentamicin are effective. Otitis externa is typically treated with ear drops containing acetic acid, antibacterial, and/or steroids to reduce inflammation; ear drops may also include antifungals because fungi can sometimes cause or contribute to otitis externa. Propionibacterium acne (Cutibacterium acnes) Cutibacterium species (formerly termed Propionibacterium species) are members of the normal microbiota of the skin, living deep inside pores and follicles, oral cavity, large intestine, conjunctiva, and external ear canal. P. acnes ferment lactose into propionic acid under anaerobic conditions, from which the genus name derives. Cell morphology 7 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two Propionibacterium acnes, a gram-positive, non-spore-forming, aerotolerant anaerobic bacillus found on skin that consumes components of sebum. Laboratory environment 1. Sampling: infected skin lesions. ‫متعدد األشكال‬ 2. Microscopically: gram positive, they are highly pleomorphic; showing curved, clubbed, or pointed ends; long forms with beaded uneven staining; and occasionally coccid or spherical forms. 3. Macroscopically: P. acnes can be cultivated on different media, such as blood, brucella, chocolate, brain heart infusion agar, under anaerobic-to- Microaerophilic conditions. Colonies on blood agar are 1 to 2 mm in diameter, typically glistening, circular, and opaque. 4. Biochemically Most strains are catalase and indole positive (convert the amino acid tryptophan into indole) in the absence of glucose. Clinical demonstration ‫ممكن الي يسوي هاي البكتيريا هو الحبوب مثال‬ Excess sebum (oil) production due to overactive sebaceous glands or blockage of a follicle can cause this bacterium to multiply. P. acnes release digestive enzymes to break down sebum and aquire nutrients, which can sometimes destabilize the cell walls in the follicle. ‫تساقط الجلد‬ Acne occurs when hair follicles become clogged by shed skin cells and sebum, causing non-inflammatory lesions called comedones. Comedones (singular “comedo”) can take the form of whitehead and blackhead pimples. Whiteheads are covered by skin, whereas blackhead pimples are not; the black color occurs when lipids in the clogged follicle become exposed to the air and oxidize. P. acnes is frequently a cause of 1. Postsurgical wound infections, particularly those that involve insertion of devices, such as prosthetic joint infections, particularly of the shoulder, central nervous system shunt infections, osteomyelitis, endocarditis, and endophthalmitis. 2. Lacremal canaliculitis 3. Dental abscess Antibiotics, such as erythromycin, administered either topically or orally, are effective, especially when coupled with other agents such as benzoyl peroxide or retinoid. Bacillus anthracis (cutaneous) Cell morphology Bacillus anthracis, a gram-positive, endospore-forming, facultative anaerobe. The typical cells, measuring 1 × 3–4 μm, have square ends and are arranged in long chains; spores are located in the center of the bacilli. Laboratory environment 1. Sampling: Specimens to be examined are fluid or pus from a local lesion 8 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two Anthrax 2. Microscopically: a gram-positive rods occurring in long chains 3. Macroscopically: Colonies of B. anthracis are round and have a “cut glass” appearance in transmitted light. Colonies on blood agar typically have a characteristic flared “comet‟s tail” appearance. 4. Biochemically: catalase and indole positive, oxidase negative Clinical demonstration Transmission can occur via direct contact of infected animal tissue or products.‫الصوف أو الشعر‬ ‫خدش‬ such as wool or hair. Anthrax endospores enter the body through abrasions of the skin. This form of the disease is called cutaneous anthrax. The typical lesion of cutaneous anthrax is a painless ulcer with a black eschar (crust, scab). Local edema is striking. The lesion is called a malignant pustule. Untreated cases progress to bacteremia and death. Once in the skin tissues, B. anthracis endospores germinate and produce a capsule, which prevents the bacteria from being phagocytized, and two binary exotoxins that cause edema and tissue damage. Anthrax toxins are made up of three proteins: protective antigen (PA), edema factor (EF), and lethal factor (LF). The first of the two exotoxins consists of a combination of protective antigen (PA) and an enzymatic lethal factor (LF), forming lethal toxin (LeTX). The second consists of protective antigen (PA) and an edema factor (EF), forming edema toxin (EdTX). The localized infection can eventually lead to bacteremia and septicemia. If untreated, cutaneous anthrax can cause death in 20% of patients. Broad spectrum antibiotics such as penicillin, erythromycin, and tetracycline are often effective treatments. B. anthracis has been used as a biological weapon ‫فطريات الجلد‬ Mycoses of the Skin Many fungal infections of the skin involve fungi that are found in the normal skin microbiota. Some of these fungi can cause infection when they gain entry through a wound; others mainly cause opportunistic infections in immunocompromised patients. Other fungal pathogens primarily cause infection in unusually moist environments that promote fungal growth; for example, sweaty shoes, communal showers, and locker rooms provide excellent breeding grounds that promote the growth and transmission of fungal pathogens. ‫غرف تبديل املالبس أماكن خصبة ممتازة‬ Tineas (Dermatophytes) ‫الجلدية‬ Cell morphology Dermatophytes, fungal molds that require keratin, a protein found in skin, hair, and nails, for growth. There are three genera of dermatophytes, all of which can cause cutaneous mycoses: Trichophyton, Epidermophyton, and Microsporum. Laboratory environment 9 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two 1. Sampling: skin scraping 2. Microscopically: Microscopic morphology using either a slide culture or sticky tape prep stained with lactophenol cotton blue. Direct microscopic evaluation of specimens from skin scrapings, hair, or nails can be used to detect fungi. Generally, these specimens are prepared in a wet mount using a potassium hydroxide solution (10%–20% aqueous KOH), which dissolves the keratin in hair, nails, and skin cells to allow for visualization of the hyphae and fungal spores. 3. Macroscopically:  A Wood‟s lamp (black lamp) with a wavelength of 365 nm is often used. When directed on a tinea, the ultraviolet light emitted from the Wood‟s lamp causes the fungal elements (spores and hyphae) to fluoresce.  The specimens may be grown on Sabouraud dextrose CC (chloramphenicol/cyclohexamide), a selective agar that supports dermatophytes growth while inhibiting the growth of bacteria and saprophytic fungi. Clinical demonstration Dermatophytes are commonly found in the environment and in soils and are frequently transferred to the skin via contact with other humans and animals. Fungal spores can also spread on hair. Many dermatophytes grow well in moist, dark environments: 1. Tinea pedis (athlete‟s foot) commonly spreads in public showers, and the causative fungi grow well in the dark, moist confines of sweaty shoes and ‫ينتشر غالبًا في بيئات املعيشة املشتركة ويزدهر في املالبس‬ socks..‫الداخلية الدافئة والرطبة‬ 2. Tinea cruris (jock itch) often spreads in communal living environments and thrives in warm, moist undergarments. 3. Tineas on the body (tinea corporis) often produce lesions that grow radially and heal towards the center. This causes the formation of a red ring, leading to the misleading name of ringworm Allylamine ointments that include terbinafine are commonly used; miconazole and clotrimazole are also available for topical treatment, and griseofulvin is used orally. Cutaneous Aspergillosis Cell morphology 1. Foot cell: It is the vegetative structure of the cell called the vegetative hyphae. It is found attached to the substratum, through which the hypha absorbs the nutrient for its further growth. Foot cell is generally L or T shaped. When it grows, it gives rise to the conidiophore. 10 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two 2. Conidiophore: It is long, slender and perpendicular to the foot cell or vegetative hyphae. Conidiophore is the erect hyphal branch, which enlarges at an apex and gives rise to the vesicle. 3. Vesicle: It is rounded, elliptical or club-shaped, which develops a layer of cells called phialides. 4. Conidia: These are the exogenous reproductive structure evolving from the sterigmata. The conidia appear in chains and are having a basipetal arrangement, in which the youngest conidia present at its base and the oldest conidia at the top. Laboratory environment 1. Sampling: skin biopsy. 2. Microscopically: branching hyphae, budding yeast cells or both. 3. Macroscopically: Colonies are usually fast growing, white, yellow, yellow- brown, brown to black or shades of green Clinical demonstration Primary cutaneous aspergillosis usually occurs at the site of an injury and is most often caused by Aspergillus fumigatus or Aspergillus flavus. Opportunistic infections can occur in health-care settings, often at the site of intravenous catheters, venipuncture wounds, or in association with burns, surgical wounds, or occlusive dressing. Treatment involves the use of antifungal medications such as voriconazole (preferred for invasive aspergillosis), itraconazole. Candidiasis of the Skin and Nails Cell morphology 1. Small, oval, measuring 2-4 µm in diameter. 2. Yeast form, unicellular, reproduce by budding. 3. Single budding of the cells may be seen. 4. Both yeast and pseudo-hyphae are gram-positive. 5. Polymorphic fungus (yeast and pseudohyphal form) 6. 80-90% of cell wall is carbohydrate Laboratory environment 1. Sampling: Specimens can be Exudates, Tissues, and Scrapings. 2. Microscopically: Candidiasis of the skin and nails is diagnosed through clinical observation and through culture, Gram stain, and KOH wet mounts. 3. Macroscopically: Colonies are: Creamy white, smooth colonies on SDA, Green colonies on CHROM agar. Clinical demonstration 1. Candida folliculitis: infection and inflammation of hair follicles, rash may appear as pimples. 11 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two 2. Candidal intertrigo: infection of skin located between intertriginous folds of adjacent skin. 3. Candidal paronychia: inflammation of the nail fold. 4. Candidal onychomycosis: nail infection 5. Perianal candidiasis: irritation of the skin at the exit of the rectum. 6. Chronic mucocutaneous candidiasis: immune disorder of T cells, deficient of CMI. 7. Congenital cutaneous candidiasis: skin condition in new borne babies caused by premature rupture of membranes together with a birth canal infected with C. albicans..‫منطقة حفاضات الطفل‬ 8. Diaper candidiasis: infection of a child‟s diaper area. 9. Erosio interdigitalis blastomycetia: characterized by an oval shaped area of macerated white skin on the web between and extending onto the sides of the fingers. Cutaneous candidiasis can be treated with topical or systemic azole antifungal medications. Sporotrichosis Cell morphology 1. Sporothrix schenckii is a dimorphic fungus. 2. In the basic mycological culture at 25°C, it has a filamentous form that is composed of hyaline, septate hyphae 1 to 2 μm wide. 3. The fungal growth in the colonies is characterized by branched septate hyphae which produce small distinct asexual spores known as conidia of 3–5 μm, which are brown in color. 4. The conidia are produced by conidiophores, which arise at right angles from the septate hyphae. 5. The conidiophore, are tapered at the ends. 6. The formed conidia are clustered on tiny denticles at the apex of the conidiophore forming a flower-like appearance. Laboratory environment 1. Sampling: Pus, synovial fluid, sputum, blood, or tissue fragment 2. Microscopically: Microscopic morphology can be observed by staining a slide culture with lactophenol cotton blue. 3. Macroscopically: Incubation is performed at 25°C using Sabouraud dextrose agar or potato dextrose agar. Colonies usually appear within 3 to 5 days and present a creamy white color that, in a few days, convert into the characteristic brown-black leathery colonies. Clinical demonstration Commonly known as rose gardener‟s disease or rose thorn disease. Sporotrichosis is often contracted after working with soil, plants, or timber, as the fungus can gain 12 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two entry through a small wound such as a thorn prick or splinter. Sporotrichosis can generally be avoided by wearing gloves and protective clothing while gardening and promptly cleaning and disinfecting any wounds sustained during outdoor activities. Sporothrix infections initially present as small ulcers in the skin, but the fungus can spread to the lymphatic system and sometimes beyond. When the infection spreads, nodules appear, become necrotic, and may ulcerate. As more lymph nodes become affected, abscesses and ulceration may develop over a larger area (often on one arm or hand). In severe cases, the infection may spread more widely throughout the body, although this is relatively uncommon. Pityriasis versicolor Cell morphology ،‫ال تعد سعفة الجلد امللونة عدوى فطرية جلدية‬ Tinea versicolor is not a dermatophyte infection. The causative organisms are in the genus Malassezia (formerly known as Pityrosporum). The KOH preparation findings in tinea versicolor are considered diagnostic. The preparation demonstrates both short hyphae and yeast cells in a pattern that is often described as "spaghetti and meatballs" Malassezia species are difficult to grow in the laboratory so scrapings may be reported as culture negative Laboratory environment Pityriasis versicolor fluoresces blue-green on examination using a Wood lamp Clinical demonstration Malassezia is lipid dependent, and the greater sebum production by cutaneous sebaceous glands on the upper body may contribute to the predominance of tinea versicolor in this location. Tinea versicolor (pityriasis versicolor) is a common superficial fungal infection that typically presents with hypopigmented, hyperpigmented, or erythematous macules on the trunk and proximal upper extremities. The term "versicolor" refers to the variable changes in cutaneous pigmentation that occur. Tinea versicolor may persist for years without treatment. Recurrence is common after successful treatment. In temperate climates, tinea versicolor often recurs during the warmer months of the year. Spontaneous resolution is possible Tinea nigra Cell morphology Tinea nigra is an uncommon superficial mycosis, often grouped with the dermatophytes, but caused by the melanin-producing dimorphic yeast Hortaea 13 Alkafeel University- Bacteriology and mycology-Dr Ahmed Alshammari –lecture Two werneckii. The organism lives in soil, sewage, decaying vegetation, and also has been found on shower stalls in humid environments. Lab environment KOH preparation of skin scrapings reveals hyphae. If a skin biopsy is done, the pigmented organisms can be seen in the stratum corneum. Clinical demonstration The typical lesion is a well-demarcated, asymptomatic, and brown to black patch of the palmar or plantar skin, resembling a stain. Tinea nigra is treated with a topical antifungal preparation, such as miconazole, clotrimazole, or terbinafine cream. White pedra and Black pedra The Spanish word “piedra” means stone and justifies its usage to denote conditions characterized by presence of hard nodules along the hair shaft, namely white and black piedra Cell morphology and lab environment White piedra is caused by yeast-like fungi belonging to the genus Trichosporon, which has now been documented to be a part of human microbiome. Black piedra, caused by the dematiaceous filamentous fungus Piedraia hortae. In white piedra, microscopically reveals hyaline nodules consisting of arthroconidia and some blastoconidia. The culture is white-yellowish yeast-like, with a cerebriform aspect. In black piedra, microscopically reveals dark nodules attached to the shaft, containing several ascus, with two to eight fusiform, curved ascospores. The culture is dark, and its growth is slow Clinical demonstration White or beige in color and relatively softer than those of black piedra, which are black and stone hard. 14