Antifungal agents
Griseofulvin: Griseofulvin interact with microtubules and disrupt mitotic - spindle function
of the fungal cell (cause shrinkage of fungal hyphae).
hqve no role on fungi producing
systimc mycosis
Amphotericin B: belonging to polyenes group. Amphotericin B firmly bind to ergestrol
(sterol) in the cell membrane, such binding increase the permeability of the cell with leak
essential components It is nehortoxix and does not enter CSF
Flucytosine (5 flurocytosine): used in conjucation with Amph.B , The drug accumulated in
fungal cells and converted by cytosine deaminase to 5 fluorouracil, an inhibitor of the
thymidylate synthetase (this enzyme is essential for DNA synthesis).
pentreat well to all
tissues include CSF
Azoles compound: The azole used for systemic mycosis, include ketaconazole, fluconazole
and itraconzole. less toxic than Amph. B. Miconazole and clotrimazole which are toxic for
systemic administration, are used as topical agents.
All antifungal azole act by inhibition of fungal ergestrol biosynthesis which lead to
alterations in fungal membrane structure and function.
Echinocandins:act on a compound of fungal cell wall
Nystatin: Is a polyene antifungal. Related to amph.B , used in local and gastrointestinal
candida
Allylamines:The mechanism of action is inhibition of an essential step in fungal ergosterol
synthesis.
Other topical antifungal agents:
a) Tolnaftate: Its principal use is in tinea pedis,. It is inactive against Candida.
b) Whitfield's ointment: Is a mixture of benzoic and salicylic acid, the usual use for tinea
pedis.
c) Sodium thiosulfite for tinea versicolor.
Fungal diseases: known as mycosis devide into :
1. Superficial mycosis.
2. Cutaneous mycosis.
3. Subcutaneous mycosis.
4. Endemic (primary systemic) mycosis.
5. Opportunistic mycosis.
Two properties of fungi appear to be very important in the pathogenesis of the disease they
caused.
A. Tissue tropism.
B. The ability of many fungi to incite sensitivity especially delayed type sensitivity in the
host. account in large part for the pathologic effects produced.
Superfcial mycoses:
Include diseases of skin and hair that show few complaints. The invading pathogen is
confined to the stratum corneum with little or no tissue reaction.
A. Pityriasis versicolor
Pityriasis versicolor (Tinea versicolor)
-->
1. chronic mild infection of stratum corneum .
2. Present as varible asymptomatic patches of hypo or heyperpigmented maculen
3. Medical attention is only for cosmotic reason .
4. May show itching or burning at area of lesion
Etiological agent:
Malassezia furfur is a member of the normal flora of human skin.
The fungus cause catheter - aquired fungemia in adults, and specially neonates who are
receiving intravenous lipid.
Epidemiology
1. The distribution of the disease is Worldwide.
2. Malassezia furfur is a member of the normal flora of the skin. That cause disaese in
under certain effect ; The important predisposing factors are poor hygiene and excess
sweating, systemic corticosteroid also increase susceptibility to the disease.
3. The fungus has not been found as a free - living saprophyte.
4. Transsmited from human to human driectly or indirctly
Laboratory Diagnosis
a) Direct examination:
mounted with 20% KOH , apear as cluster of buding yeast cell
b) Isolation of M. furfur in culture on sabouraud agar .
c) A clinical diagnosis can be made in typical cases, and also by
d) the use of wood's light, that the infected lesions show a pale yellow fluorescence under
dark condition.
Treatment
1. The topical azoles antifungal work well in pityriasis versicolor.
2. Daily application of an aqueous solution of sodium hyposulfte or 3% salicylic acid in
70% alcohol is effective.
3. Selsun suspension may be applied in the form of shampoo.
4. Cloth should be boiled to prevent reinfection after cure.
B.Tines Nigra
Tines nigra is a
superficial chronic
and asymptomatic
fungal infection of the
epidermis
characterized by
brown to black
macules.
Etiological agent
The causative
orgarism is Exophiala
werneckii.
(dematiaceous
fungus).
Occur in soil infection
by contminated
matrial .
Laboratory Diagnosis
a) Direct
examination.
Mounted with 20%
KOH and apear as
1. Pigmented light
brown to green
2. Branching septate
hyphae
3. Chlamydospore
alao seen
b) Direct culture.
Treatment
A. Respond to the
topical application
of fungicidal
preparation such
as Benzoic acid
compound
ointments.
B. Topical azole
creams such as
econazole are
also effective.
C. Piedra
Infection limited to the hair shafts.
tow varites of piedra black and white
1. Black piedra is caused by piedraia
hortae.
2. produce hard black nodule on the hair
withtin the scalp
3. the nodule are firmly attatched to hair
shaft
4. growth occur on the hair so weaken and
break esaly .
1. White piedra is caused by the yeast
Trichosporon beigelii.
2. produce light colored nodule on bread
and mustache
3. the6 are less firmly attatched to hair shaft
4. however extensive growth may occur
and hair weaken and break .
Laboratory Diagnosis
Direct examination.
The crushed nodules (from black piedra)
show numerous asci containing two to eight
single - celled fusiform, ascospores.
In case of white piedra, the crused nodules
show only arthorspores and blastospores,
but no asci.
Culture.
on sabouraud's agar
Treatment:
1) By shaving the hair, clipping the hair
closely result in cure.
2) The use of a solution of bichloride
mercury .(for both piedra).