SUPERFICIAL, CUTANEOUS, SQ INFECTIONS Flashcards
organisms that get their energy
from dead or decaying organic matter.
Saprophytic organisms
lipophilic yeast living on the skin as part of the normal flora that causes Pityriasis versicolor/ Tinea versicolor / AN-AN
Malassezia furfur (Pityrosporum orbiculare)
Malassezia furfur (Pityrosporum orbiculare) exist as dimorphic form TRUE OR FALSE
TRUE
grow in normal body temp 37 degrees
Celsius
Yeast
grow at lesser temp around 25 degrees Celsius
Molds
Color of Malassezia furfur under Wood’s UV light
pale greenish color
procedure that uses transillumination
to detect any bacterial or fungal infections, or to examine the skin for any changes in pigmentation.
Wood’s lamp
clusters of thick-walled round,
budding yeast-like cells, and short angular hyphal forms
“Spaghetti and meatballs”
Tinea versicolor or “An-an” Caused by Malassezia furfur (Pityrosporum orbiculare)
A common saprophytic fungus that is found in humid countries around the world. Grows as yeast → Older hyphae with mycelia and conidia
Hortaea werneckii
Characterized by brown to black macules which usually occur in the hands and occasionally the plantar surface of the skin
Tinea nigra
Culture of Hortaea werneckii
Sabouraud’s dextrose agar (SDA)
Treatment Tinea nigra
Topical treatment with Whitfield’s ointment (benzoic acid compound) & Imidazole agent twice a day for 3-4 weeks is effective.
Forms hard black nodules on the shafts of the scalp, beard, moustache, and pubic hair. reported following the sharing of combs and sharing of combs and hairbrushes.
BLACK PIEDRA
BLACK PIEDRA caused by __________
Piedra hortae
asci sexual spore bearing cell of the fungi.
BLACK PIEDRA
TX black piedra
Terbinafine 250 mg tablet a day for 6 weeks.
Irregular, soft, white, or light brown nodules, 1.0 1.5 mm in length, firmly adhering to the hairs. caused by Trichosporon beigelii
WHITE PIEDRA
10% KOH and Parker ink or calcofluor white mounts shows hyphae that develops into arthroconidia.
WHITE PIEDRA
TX WHITE PIEDRA
Topical application of an imidazole agent may be used to prevent reinfection & Selenium sulfide shampoo
Conidia are large, pencil shaped, smooth, thin walled and septated (0 10 septa); colonies are a loose mycelium that grows in a variety of colors.
TRICHOPHYTON SP.
TRICHOPHYTON SP. infects
SKIN, HAIR, AND NAILS
MICROSPORUM Infect
SKIN AND HAIR RARELY NAILS
The loose, cottony mycelia produce macroconidia which are thick walled, spindle shaped, multicellular, and echinulate (spiny) “ spindle shaped with characteristic spine at the end.”
Microsporum
EPIDERMOPHYTON FLOCCOSUM Infect
SKIN AND NAILS AND RARELY HAIR
Form yellow colored, cottony cultures and are usually readily identified by the thick, bifurcated hyphae with multiple smooth, club shaped macroconidia. “similar to a cotton bud.”
EPIDERMOPHYTON FLOCCOSUM
associated with humans only. Transmission from man to man is by close contact or through contaminated objects.
ANTHROPOPHILIC
Associated with animals.
Transmission to man is by close contact with animals
ZOOphilic infection
Associated with animals.
Transmission to man is by close contact with animals
Zoophilic infection
usually found in the soil and are transmitted to man by direct exposure.
Geophilic infection
Most common, presents with scaling and redness between
the toes and may have maceration.
TINEA PEDIS: INTERDIGITAL PATTERN
Sharply marginated scale distributed along lateral borders of feet, heels, and soles.
TINEA PEDIS: MOCASSIN PATTERN / chronic hyperkeratotic type
Vesicles or bullae usually found on the instep of the foot.
TINEA PEDIS: VESICULOBULLOUS PATTERN
Fungistatic (stops fungi growth) Works by inhibiting ergosterol synthesis.
Imidazole:
Fungicidal (kills fungi) Works by interfering the squalene
monooxygenase.
Allylamines:
Fungicidal and fungistatic. Inhibits the aspects of the cell growth and fungi
metabolism.
Ciclopirox:
Fungal hyphae and spores (arthroconidia) cover the outside of the hair.
ECTOTHRIX INVASION
Cuticle of the hair remains intact and infected hairs do not fluoresce under Wood’s ultraviolet light.
ENDOTHRIX INVASION
Common agents include: ECTOTHRIX INVASION
Microsporum canis
Microsporum gypseum
Trichophyton equinum
Trichophyton verrucosum
ENDOTHRIX INVASION Caused by:
Trichophyton tonsurans
Trichophyton violaceum
caused by T. schoenleinii, produces favus-like crusts
or scutula and corresponding hair loss. A yellow, saucer-shaped crust that is formed in a mass of hyphae, pus, and scales found on the scalp which eventually leads to loss of hair.
FAVUS
hallmark of Cell-mediated immunity (CMI)
Granulomatous inflammation
Culture Tinea capitis: Selective media - Sabouraud’s dextrose agar containing _____________ and _____________ -> incubate at 25 ̊C
cycloheximide and chloramphenicol
Culture Tinea capitis: Selective media - Sabouraud’s dextrose agar containing _____________ and _____________ -> incubate at 25 ̊C
cycloheximide and chloramphenicol
isolates the fungi from other contaminating bacteria
Chloramphenicol
inhibit the saphrophytic fungi
Cycloheximide
Inhibits squalene epoxidase, which is an important
enzyme in the synthesis of ergosterol.
Tolfnatate (Tinactin)
Inhibits cytochrome 450 dependent enzyme systems at
the demethylation step from lanosterol to ergosterol.
Azole
Inhibits the squalene monooxygenase that blocks the
synthesis of ergosterol.
Terbinafine (Lamisil)
Inhibits the synthesis of beta (1,3)-D-Glucan of the fungal cell wall.
Echinocandins (Caspofungin)
Inhibits the microtubule assembly in the fungi. It is a
fungistatic agent and usually function is improved when
you use this in combination with selenium sulfide
shampoo.
Griseofulvin
It is a well-known pathogen in humans and animals.
* “Rose-gardener’s disease”
Sporothrix schenckii
fungi would usually be inoculated into the skin after being prick with a thorn from plants or flowers wherein the soil would contain these common fungi.
SPOROTRICHOSIS
Contaminated plant matter penetrates the skin, and the
pathogen forms a nodule, then spreads to nearby lymph
nodes; Most common
LYMPHANGITIC FORM; SPOROTRICHOSIS
Acneiform, nodular, ulcerated, verrucous. Infiltrated plaques, red scaly patches. appear similar to an acne or a wart.
FIXED/ ENDEMIC FORM; SPOROTRICHOSIS
Follows inhalation with Chronic lung nodules cavitation. The infection can occasionally involve the CNS,
the lungs and even the GIT. Fatal condition
SYSTEMIC FORM; SPOROTRICHOSIS
First choice of treatment for uncomplicated cutaneous
sporotrichosis
Potassium iodide:
is a chronic granulomatous infection of the skin and subcutaneous tissue caused by several dematiaceous fungi.
CHROMOBLASTOMYCOSIS
Fungi that have melanin or melanin-like pigment in the
walls of their hyphae and spores
Dematiaceous fungi
Slow growing Cauliflower-like lesions, which may
ulcerate later on.
CHROMOBLASTOMYCOSIS
produce thick- walled cells with multiple internal transversepta or chambers that are known as single or multicellular clusters called sclerotic of muriform bodies. They resemble copper pennies.
chromoblastomycosis
Chronic, infectious, inflammatory disease, slowly progressive granulomatous infection of skin & subcutaneous tissue with involvement of underlying fasciae, and bone in progression.
Maduromycosis (Madura foot)
Firm, painless nodule
Many nodules – lumpy appearance
Multiple sinus tracts draining purulent discharge.
Pus discharge containing granules and grains
(microcolonies)
MYCETOMA / Maduromycosis (Madura foot)
MYCETOMA / Maduromycosis (Madura foot) TRIAD
TDP:
Tumefaction (swelling of extremity)
Draining sinuses
Presence of granules/grains
Common in India and Sri Lanka. Diving and swimming in stagnant water. The classical lesion is pedunculated or polypoid mass that is found on the mucus membrane. Painless itching accompanied with mucoid discharge.
RHINOSPORIDIOSIS
Causes RHINOSPORIDIOSIS
Rhinosporidium seeberi
Causes RHINOSPORIDIOSIS
Rhinosporidium seeberi
TX RHINOSPORIDIOSIS
DAPSONE / Surgery
