Dermatophytes
Summary
TLDRThis presentation from Andy Alpa of Duke University's School of Medicine delves into dermatophyte fungi, the most common cause of superficial skin infections. These keratinophilic fungi infect keratinized tissues like skin, hair, nails, and feathers. The talk covers clinical manifestations, transmission through fomites, and the unique ecological niche of anthrophilic, zoophilic, and geophilic dermatophytes. It also discusses diagnosis through skin scrapings and microscopy, and treatment options ranging from topical antifungal agents to systemic therapy for conditions like tinea capitis and onychomycosis. The presentation highlights the importance of addressing these infections to prevent more serious complications.
Takeaways
- 🦠 Dermatophytes are a group of fungi that cause superficial skin infections, commonly known as ringworm, and are among the most widespread infectious agents globally.
- 🔬 Dermatophytes are classified into three ecological groups based on their preferred host: anthrophilic (human tissue), zoophilic (animal tissue), and geophilic (environment).
- 📚 The presentation's objectives are to review clinical manifestations of dermatophyte infections, discuss how they are acquired, and consider diagnosis and treatment methods.
- 👨⚕️ A typical patient case described involves a 70-year-old man with scaling, itching, and nail changes, indicative of athlete's foot and a fungal nail infection.
- 🌱 Dermatophytes are keratinophilic, meaning they primarily grow on keratinized tissue such as skin, hair, nails, and feathers, which is a remarkable adaptation.
- 🧬 In the lab, dermatophytes grow slowly on artificial media, and specific species can be identified by observing their growth and development.
- 🚫 Dermatophyte infections typically do not invade deep dermal structures, as they grow only in the most superficial skin layers, causing symptoms through their metabolic products.
- 🤝 Dermatophytes are transmitted by direct contact or indirectly through fomites, such as hotel carpets, locker rooms, swimming pools, and shared personal items.
- 🔍 Dermatophyte infections are diagnosed by their clinical appearance, skin scrapings under a microscope, and sometimes fungal culture or biopsy.
- 💊 Treatment for dermatophyte infections often involves topical antifungal agents for hands, feet, or body, with systemic therapy required for conditions like tinea capitis.
- 🛑 Onicomicosis, or nail infections, is particularly challenging to treat due to the deep location of fungi in nail structures, requiring prolonged treatment with potentially higher cure rates but also more side effects.
Q & A
What is the main topic of the presentation by Andy Alpa from Duke University?
-The presentation explores a group of fungi known as dermatophytes, which are the cause of superficial skin infections and are arguably the most common infectious agents in the world.
What are the learning objectives for the module on dermatophyte infections?
-The learning objectives are to review the clinical manifestations of infections due to these fungi, discuss how one might acquire dermatophyte infections, and consider how to diagnose and treat these common infections.
What is the typical presentation of a patient with dermatophyte infection affecting the feet?
-A typical patient may present with scaling, itching, thickening, and discoloration of the skin and nails on their feet, with no systemic symptoms, and the condition may have progressed over several months.
What does 'dermatophyte' mean in terms of the fungi's ecological niche?
-Dermatophytes are keratinophilic fungi, meaning they primarily grow on keratinized human and animal tissue such as skin, hair, nails, and feathers.
How are dermatophyte species categorized based on their preferred host?
-Dermatophyte species are categorized as anthrophilic (growing on human tissue), zoophilic (growing on certain animal species), and geophilic (growing in the environment).
What is the typical growth pattern of dermatophytes in a microbiology lab?
-Dermatophytes tend to grow very slowly on artificial growth medium, and specific species can be identified using the structures observed during various times of their growth and development.
How do dermatophyte infections usually present symptomatically, and what causes these symptoms?
-Symptoms of dermatophyte infections are typically due to the host's response to fungal metabolic products rather than fungal invasion, as these organisms typically only grow in the most superficial layers of the skin.
What are some common transmission sources for dermatophyte infections?
-Transmission sources include hotel carpets, locker rooms, swimming pools, shared hats and brushes, poorly washed bedding, and theater or airplane seats.
What are some common terms used to describe dermatophyte infections?
-Common terms include 'ringworm' for body infections, 'onychomycosis' for nail infections, 'tinea pedis' for foot infections, 'tinea manum' for hand infections, 'tinea cruris' for groin infections, 'tinea corporis' for body infections, and 'tinea capitis' for scalp infections.
How is the diagnosis of dermatophyte infections typically made, and what methods can be used for confirmation?
-Diagnosis is usually made by characteristic clinical appearance. Confirmation can be done by skin scrapings onto a microscope slide with potassium hydroxide to dissolve human skin and observe fungal forms, or by sending scrapings for fungal culture.
What are the general treatment approaches for dermatophyte infections involving different body parts?
-Most cases involving hands, feet, or body can be treated with topical antifungal agents. Tinea capitis often requires systemic therapy, and onychomycosis may require prolonged treatment with either topical or oral antifungal agents.
Why are dermatophyte infections considered important despite not invading deeper structures?
-Dermatophyte infections are important because they are common, can cause cosmetic changes and discomfort, and disrupt the protective skin barrier, increasing the risk for more serious infections.
Outlines
🦠 Dermatophytes: Causes and Characteristics
This paragraph introduces dermatophytes, a group of fungi responsible for skin infections, and discusses their ecological niche and adaptation to keratinized tissues. Andy Alpa from Duke University's School of Medicine presents a case study of a 70-year-old man with symptoms of athlete's foot and fungal nail infection. Dermatophytes are keratinophilic, meaning they grow on human and animal tissues like skin, hair, nails, and feathers. They are categorized into anthrophilic, zoophilic, and geophilic based on their preferred host. The paragraph also explains how dermatophyte infections are typically transmitted through fomites and the symptoms they cause, which are a result of the body's reaction to fungal metabolic products rather than invasion by the fungi themselves.
🌟 Clinical Terms and Treatment of Dermatophyte Infections
The second paragraph delves into the clinical terms used to describe dermatophyte infections and the methods for diagnosing and treating them. It explains the use of terms like 'ringworm' and 'onychomycosis' for nail infections, and how the site of infection influences the terminology (e.g., 'tinea pedis' for foot infections, 'tinea capitis' for scalp infections). The paragraph outlines the standard diagnostic process, which includes clinical appearance and skin scrapings analyzed under a microscope with potassium hydroxide. It also discusses various treatment options, emphasizing that while most infections can be treated topically with antifungal agents, some conditions like tinea capitis may require systemic therapy. The challenges of treating onychomycosis due to the deep penetration of fungi in the nail structures are highlighted, along with the considerations for using topical versus oral antifungal treatments.
🛡️ Importance and Prevention of Dermatophyte Infections
The final paragraph underscores the significance of dermatophyte infections due to their prevalence and potential to cause cosmetic issues and local irritation. It also points out that these infections can disrupt the skin's protective barrier, increasing the risk of more severe infections like cellulitis and diabetic foot infections. The paragraph concludes by emphasizing the importance of careful attention to dermatophyte infections to ensure a lasting cure and prevent long-term adverse outcomes, thus highlighting the need for proper diagnosis and treatment to maintain skin health and prevent secondary infections.
Mindmap
Keywords
💡Dermatophytes
💡Keratinophilic
💡Anthropophilic
💡Zoophilic
💡Geophilic
💡Tinea
💡Onychomycosis
💡Fomites
💡Topical antifungal agents
💡Systemic therapy
💡Pigment changes
Highlights
Introduction to dermatophytes, a group of fungi causing superficial skin infections.
Dermatophytes are the most common infectious agents worldwide.
Location of dermatophytes within the fungal Kingdom and their growth as hyaline molds.
Learning objectives: clinical manifestations, acquisition, diagnosis, and treatment of dermatophyte infections.
Case study of a 70-year-old man presenting with symptoms of athlete's foot and fungal nail infection.
Dermatophytes are keratinophilic, growing on keratinized human and animal tissue.
Ecological niches of dermatophytes: anthrophilic, zoophilic, and geophilic.
Slow growth of dermatophytes on artificial medium and identification through growth structures.
Symptoms of dermatophyte infections are due to local irritation and skin scaling caused by fungal metabolic products.
Transmission of dermatophytes through fomites and environmental sources like hotel carpets and swimming pools.
Common terms for dermatophyte infections: ringworm, onychomycosis, tinea pedis, and tinea capitis.
Diagnosis of dermatophyte infections through clinical appearance and skin scrapings.
Treatment of dermatophyte infections with topical antifungal agents for hands, feet, or body.
Tinea capitis often requires systemic therapy due to its deeper involvement in hair follicles.
Challenges in treating onychomycosis due to the deep nail structure and slow turnover.
Comparison of topical and oral antifungal agents for treating nail infections, including cure rates and side effects.
Tinea versicolor, a superficial skin infection caused by Malassezia fungi, responds to topical treatments.
Importance of treating dermatophyte infections to prevent more serious conditions and long-term outcomes.
Transcripts
this is Andy Alpa from Duke University
School of Medicine this presentation
we'll explore a fascinating group of
fungi known collectively as the dermatop
phyes the causes of superficial skin
infections and arguably the most common
infectious agents in the world in our
pathogen map the dryes are located
within the fungal Kingdom growing as
hyul
molds our learning objectives for this
module are first to review the clinical
manifestations of infections due to
these fungi second to discuss how one
might acquire dramafied infections and
third to consider how we diagnose and
treat these very common
infections let's begin with a simple and
exceedingly common patient case of a
70-year-old man who is otherwise well
but who comes to see you with scaling
and itching of his feet the symptoms
have progressed over several months and
include thickening and discoloration of
his nails he has absolutely no systemic
symptoms referable to this condition
your examination of the patient confirms
that he is healthy but that he has well
demarcated regions on his feet with
scaling of the skin and little
underlying inflammation the plantar
surfaces are prominently involved as
well as the regions between his toes he
also has nail changes with thickening
and discoloration of the nail plate this
is a classic case of what in common
parlance would be called athletes foot
with a fungal nail infection
all of these symptoms are caused by the
dermatophyte fungi dermatophytes are
keratinophilic fungi meaning that they
primarily grow on keratinized human and
animal tissue such as Skin hair nails
and Feathers this specific ecological
niche represents a remarkable adaptation
for these particular structures by these
fungi this adaptation also results in a
very narrow range of sites where
particular dropy species can be found
for example many of the causes of human
infections can only grow on human tissue
and they are therefore called anthropic
dermatophytes other species are able to
grow un certain animal species and they
are known as
zoophilic lastly a small group of these
agents can grow in the environment and
therefore they are referred to as
geophilic now mycologically these fungi
tend to grow very slowly on artificial
growth medium in the microbiology lab
specific species can be identified ifed
using the identification of structures
observed during various times of their
growth
development here we are demonstrating
various fungal features that distinguish
some of the most common dermatophytes
that cause infections in humans for the
sake of this presentation it is likely
sufficient that you just recognize a few
common
dermatophytic and troyen
once these fungi establish an infection
on human keratinized tissue such as Skin
how do they result in symptoms and
disease most of the symptoms of dery
infections are not due to fungal
Invasion since these organisms typically
only grow in the most superficial layers
of the skin such as the stratum corium
they rarely invade deep dermal
structures the local irritation and skin
scaling occur as a response to fungal
metabolic products produced during
microbial
growth although dermatophytes can be
transmitted by direct physical contact
these agents are typically transmitted
in what are refer to as fomites or the
desolated skin and Fallen hairs of
infected people and we can all come into
contact with these fomites in many areas
of of the environment however some of
the most famous sources for transmission
include Hotel carpets locker rooms and
swimming pools infected hairs are often
found in shared hats and brushes po
poorly washed bedding and either theater
or airplane
seats let's review some of the common
terms that patients and Physicians will
use to talk about dermaide infections
now patients will often refer to dery
Tois of the body as
ringworm now although this infection is
not truly caused by a worm this older
term does describe some of the most
prominent features of these
infections the infection will often
appear as a well demarcated patch with a
minimally inflammatory border containing
a region of Central clearing with skin
scaling thus the Ring of wi ringworm
demonstrated in this
image other terms include
onicomicosis indicating nail infection
due to the
dermatophytes as demonstrated in this
image anacom micosis typically presents
as a chronic and painless thickening of
the nail plate with an accumulation of
scaling debris in the nail bed this
debris often includes a mixture of human
and fungal
elements other terms will Define the
sight of infection using the word Tena
plus the Latin name of the involved body
part therefore ten angam refers to dropy
infection of the nail or
onicomicosis tenia pedus refers to
involvement of the feet or athletes foot
as demonstrated in the initial patient
case tenam manum indicates infection of
the skin of the hand a patient with dery
infection involving the inguinal region
and the inner aspect of the thigh has
tenia curus or joet a condition that is
almost exclusively observed in men dery
infection of the thorax or abdomen is
tenia corporis or
ringworm a particularly Troublesome type
of dermatophytosis is tenia capitis or
involvement of the head and scalp this
condition occurs most commonly in
children
it can be somewhat difficult to
completely eradicate and it can also
result in some degree of hair loss as
demonstrated in the top image on this
slide when the infection results in
tissue inflammation the lesion is called
a
Carion because of the deeper involvement
of the hair follicles in tiny capitus
this condition often requires systemic
therapy as opposed to simple topical
antifungal
agents the diagnosis of dropy infections
is usually made by its characteristic
clinical appearance however other
conditions can result in inflammatory
patches such as contact dermatitis and
reactions to various medicines one can
make a more definitive diagnosis by
scraping the involved skin onto a
microscope slide adding potassium
hydroxide to dissolve the human skin and
observing the fungal forms by direct
light
microscopy the skin scrapings can also
be sent for fungal culture if the
diagnosis is in doubt rarely biopsy and
histopath Analysis are needed to
diagnose this
condition on this slide I've attempted
to summarize some of the treatment
issues for D dery infections now most
cases involving the hands feet or body
can be treated with topical antifungal
agents such as the topical azol turbine
or napen treatment often requires at
least two weeks of therapy and should
extend for about one week after the
symptoms clear to ensure that all of the
fungi even those hiding in the dead
layers of the skin are well treated it's
important to note that topical NY Statin
a good agent for superficial candid
infections is not effective against
dermatophytes also patients will often
use topical steroids for many
non-specific skin eruptions but these
agents should be avoided if you are
treating dermaide
infections as I mentioned previously
tinia capitus often requires systemic
therapy to result in a cure historically
the oral antifungal agent Grizzy fulin
was used for this condition mostly due
to its acceptable safety profile in
children however Grizzy fulin must often
be used for 2 to 3 months in contrast
oral azol and oral turban likely require
much shorter courses of therapy however
cost and potential drug drug
interactions can be important issues
with these newer antifungal
agents one of the most difficult and
vexing issu of treatment is what to do
about onicomicosis or nail infections
since these fungi reside deep in the
nail structures and these structures
take many months to turn over one must
often treat onicomicosis for several
months to have any hope for
cure topical agents such as azil creams
topical turbin and various antifungal
nail lacers have a low cure rate for
this infection often less than 50% in
many clinical trials however there are
often few side effects effects from this
type of topical
therapy in contrast oral antifungal
agents have a higher cure rate but
prolonged or pulse do systemic
antifungal therapy can be very very
expensive and some serious side effects
have been noted including liver and
myocardial
toxicity one last superficial infection
of the skin that I want to mention is
not caused by a derhy fungus in contrast
to the intense scale observed with
matify infections tenia Versa color
often presents as simple pigment changes
in the skin without a significant amount
of scale or underlying inflammation it
is caused by the malisia group of fungi
organisms that require exogenous lipids
to grow such as those present on the
surface of your
body this condition is often
comparatively simple to treat responding
to topical azoles or anti dandruff
shampoos containing selenium sulfide
in conclusion we have discussed
superficial infections due to various
groups of fungi although these rarely
invade deeper
structures Derma ofy infections are
important for several reasons first they
are exceedingly common among your future
patients resulting in concerning
cosmetic changes in the skin potentially
hair loss dramatic nail changes and
local irritation also once these
infections cause A disruption of the
normally protective beer barrier of
intact skun your infected patients will
be at a higher risk for more serious
infections such as cellulitis diabetic
foot infections and bacterial infections
of the regions around the nails
therefore careful attention to these
infections can result in lasting cure
and prevention of long-term adverse
outcomes
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