3. Normal Microbiota of the Skin
Gram-positive cocci such as staphylococci and
micrococci predominate on the skin.
Diphtheroids (gram-positive pleomorphic rods), such
as Propionibacterium acnes and Corynebacterium
xerosis, are also present.
Pityrosporum ovale yeast grows on oily secretions and
responsible for the scaling skin condition known as
dandruff.
4.
5. The Antimicrobial Factors of the Skin:
keratinocytes or keratinized cells - physical barrier, prevent
water loss and entrance of microbes and toxins.
superficial layers of the skin are naturally acidic (4.8 to 6.2
depending on location)
Evaporation of sweat leaves behind a residue of solutes
including sodium chloride
skin creates antimicrobial peptides /called host defense
peptides
shedding of skin
saturated and unsaturated fatty acids or free fatty acids (FFAs)
in sebum - kill or inhibit the growth of bacterial
Perspiration and lysozyme
6. Once microbes have invaded the skin they have
various ways to avoid host defenses. They:
Hide their antigens to avoid an immune response
Kill infection-fighting cells (phagocytes)
Survive within host infection-fighting cells.
Develop resistance to antibiotics
Release toxins (intoxication)
8. Staphylococcal Skin Infections
(Bacterial Skin Disease)
gram-positive bacteria that often grow in clusters.
produce coagulase (an enzyme that causes blood
clot formation)
produce enterotoxins (toxin causing violent vomiting and
diarrhea)
Produce leukocidins (destroy or lyse white blood cells)
Produce exfoliative toxin (causes lysis of the intracellular
attachment between cells of granular layer of epidermis)
produce penicillinase (hydrolyze and inactivate penicillin)
Facultative anaerobe
pyogenic (pus-eliciting), tissue invasive and produces
purulent (pus-filled) lesions.
9. Streptococci
produce hemolysins (lyse not only red blood cells, but
almost any type of cell)
classified based on their hemolytic properties:
Alpha hemolytic species cause oxidization of iron in
hemoglobin molecules within red blood cells, giving it a
greenish color on blood agar.
Beta hemolytic species cause complete rupture of red
blood cells. On blood agar, this appears as wide areas clear
of blood cells surrounding bacterial colonies.
Gamma-hemolytic species cause no hemolysis.
10.
11. Propionibacterium acnes
aerotolerant anaerobic
Gram-positive bacterium (rod)
live deep within follicles and pores
use sebum, cellular debris and metabolic byproducts from the
surrounding skin tissue as their primary sources of energy and
nutrients
produces propionic acid (end product of
their anaerobic metabolism)
catalase (catalyzes the decomposition of hydrogen peroxide
into water and oxygen)
release lipases to digest a surplus of the skin oil, sebum, that
has been produced
Their activity is partially responsible for the odor of sweat.
12. Pseudomonas aeruginosa
Gram-negative rod measuring 0.5 to 0.8 µm by 1.5 to 3.0
µm
aerobic and anaerobic
opportunistic human pathogen
optimum temperature for growth is 37 degrees, and as
high as 42 degrees
secretes exotoxin A (toxic protein that catalyzes the ADP-
ribosylation to form ADP-ribosyl-EF-2, which inhibits the
protein synthesis of the host’s cells)
Elastase (an extracellular zinc protease, attacks eukaryotic
proteins such as collagen and elastin and destroys the
structural proteins of the cell; also breaks down human
immunoglobin and serum alpha proteins)
pyocyanin (blue-green)
Pyoverdine (yellow-green
pyorubin (red-brown)
13. P. aeruginosa groups tend to form biofilms, which are
complex bacterial communities that adhere to a variety
of surfaces, including metals, plastics, medical implant
materials, and tissue. Biofilms are characterized by
“attached for survival” because once they are formed,
they are very difficult to destroy.
14. Acne or Acne Vulgaris
caused by different factors such as clogged skin follicles,
production of an oily substance or sebum and a
bacterium called Propionibacterium acnes
strikes boys more often and more severely
inflammation of the sebaceous follicles are located on the
face, back, chest, and upper arms
during adolescene, a surge of androgen hormones causes
the sebaceous glands to make too much sebum and too
many skin cells within the hair follicles
sebum and dead skin cells combine with bacteria inside
the follicles form plugs :
called open comedones (blackheads)
closed comedones (whiteheads). Rupture of a
whitehead causes inflammation, producing papules
(rounded bumps), pustules (blister-like lesions),
nodules, and cysts.
ointments such as benzoyl peroxide, a powerful
antibacterial, or Retin-A
15.
16. FOLLICULITIS, BOILS, AND CARBUNCULOSIS
Folliculitis is a bacterial infection of the hair
follicle that causes formation of a pustule – a
collection of pus beneath the outer skin layer.
The infection can be :
Superficial – redness and pustule is in a single
follicle
Deep – extensive follicular involvement and
may be painful
furuncles/furunculosis or commonly known
as boils is a red, tender nodule surround a
follicle with one draining point
carbuncles/carbunculosis is extremely
painful, deep abscess that drain through
many openings onto the skin surface, usually
around several hair follicles
17. common cause is the bacterium called Staphylococcus
aureus; and could also be Pseudomonas
Cleaning the infected area thoroughly with soap and water
Applying warm, wet compresses to promote drainage from the
lesions
Topical antibiotics, such as Bactroban ointment
Extensive infection, systemic antibiotics (E-Mycin or Dynapen)
Never squeeze a boil because that may cause it to rupture
into the surrounding area
18. IMPETIGO (school sores)
tiny blisters that erupt, exposing the skin beneath
spreads easily among infants, young children, and the elderly
caused by bacterial infection including the S. aureus (Exfoliative toxin
A) end less commonly, group A beta-hemolytic streptococci.
2 types:
Nonbullous impetigo:
Caused Staphylococcus aureus, or Streptococcus pyogenes or
combinatio of both
typically begins with a small red macule that turns into a pus-filled
vesicle. When the vesicle breaks, a thick yellow crust forms the
discharge
Bullous impetigo:
Staphylococcus aureus
a thin-walled vesicle opens, and a thin, clear crust forms from the
discharge
19.
20. STAPHYLOCOCCAL SCALDED SKIN SYNDROME (SSS)
skin develops a scalded appearance marked by redness,
peeling, and necrosis (tissue cell death)
most common in infants ages 1 to 3 months but may
develop
Mortality is 2% to 3%
caused by Group II S. aureus
Skin changes pass through three stages:
Erythema: redness becomes visible, usually around the
mouth and other orifices. The skin becomes tender;
Nikolsky´s sign (slight rubbing of the skin results in
exfoliation of the outermost layer) may appear.
Exfoliation: (24 to 48 hours later): Superficial erosions
and minimal crusting occur. Large, flaccid, fluid-filled
blisters erupt and may spread over extensive areas of
the body.
Desquamation: In this final stage, affected areas dry up
and powdery scales form
21. Day 1
Day 5
Day 3
Staphylococcal Scalded Skin Syndrome - A Case
Report
Jayakar Thomas MD, PhD
Chennai, India
on March 10, 2005
1-year-old girl
A series of pictures are shown from day
1 to day 5 The child was treated with
parenteral antibiotics and supportive
measures.
22. TINEA/DERMATOPHYTOSIS
also called ringworm is a fungal infections that
are on the surface of the skin
Scalp (tinea capitis)- characterized by small,
spreading papules on the scalp, causing patchy
hair loss with scaling. These papules may
progress to inflamed, pus-filled lesions.
Body (tinea corporis) –produces flat lesions on
the skin at any site except the scalp, bearded
skin, or feet. These lesions may be dry and
scaly or moist and crusty; as they enlarge, their
centers heal, producing the classic ring shaped
appearance.
Bearded skin (tinea barbae)- It is uncommon
infection affects the bearded area of the face in
men.
23. Nails (tinea unguium) – Infection typically
starts at the tip of one or more toenails and
produces gradual thickening, discoloration,
and crumbling of the nail, with buildup of
debris under it. Eventually, the nail may be
destroyed completely.
Feet (tinea pedis) – The infection, commonly
known as athlete´s foot, causes scaling and
blisters between the toes. Severe infection
may lead to inflammation, with severe itching
and pain on walking.
Groin (tinea cruris) – It is commonly known
as jock itch. This infection produces red,
raised, sharply defined, itchy lesions in the
groin that may extend to the buttocks, inner
thighs, and external genitalia.
Topical agents: Ketoconazole cream, Naftin,
Loprox, Lamisil, Halotex, and Tinactin
24. Wart/ Verrucae
There are as many as 10 varieties of warts, the most
common considered to be mostly harmless.
Types:
Common wart (Verruca vulgaris), rounded surface
with roughened surface, most common on hands,
but can grow anywhere on the body. HPV types 2
and 4 (most common); also types 1, 3, 26, 29, and
57 and others.
Flat wart (Verruca plana), a small, smooth
flattened wart, flesh-coloured, which can occur in
clusters of up to several hundred; most common
on the face, neck, hands, wrists and knees; HPV
types 3, 10, and 28.
Filiform or digitate wart, a thread- or finger-like
wart, most common on the face, especially near
the eyelids and lips
25. Genital wart (venereal wart, Condyloma
acuminatum, Verruca acuminata), a wart that
occurs on the genitalia.
Periungual wart, a cauliflower-like cluster of
warts that occurs around the nails.
Plantar wart (verruca, Verruca plantaris), are
flat or slightly elevated. They occur singly or in
large clusters, a hard sometimes painful lump,
often with multiple black specks in the center;
usually only found on pressure points on the
soles of the feet; (myrmecia) - HPV type 1
(most common); also types 2, 3, 4, 27, 28, and
58 and others.
26. Treatment:
Electrodesication and curettage: Uses high-
frequency electric current to destroy the wart, then
surgically removes dead tissue at the base and
applies an antibiotic ointment. This method is
effective for common, filiform, and occasionally
plantar warts.
Cryotherapy: The doctor uses liquid nitrogen to kill
the wart. The resulting dried blister is peeled off
several days later. This method is used for
periungual warts and for common warts on the
face,arms and legs, penis, vagina and anus.
Acid therapy: The person applies acid drops or
plaster patches impregnated with acid every 12 to
24 hours for 2 to 4 weeks.
25% podophyllin in compound with tincture of
benzoin: this treatment is used for veneral warts.
27.
28. Shingles/Herpes Zoster
an acute inflammation of the dorsal root ganglia on one side of
the body, caused by infection with varicella –zoster herpes
The herpes zoster virus infects the nerves that send signals to the
skin, eyes, and ears. Each nerve emanates from the spine,
banding and branching about the body to send its signals to a
skin area called dermatome.
The shingles rash erupts along the effected nerve, covering the
skin in one or several of the dermatomes. The thoracic and
lumbar dermatomes are most commonly affected.
supportive treatment: calamine lotion or another drug to relieve
itching like aspirin or pain reliever
prophylactic use of the human hyperimmune globulin prepared
against the virus is useful for preventing the onset of symptoms of
shingles
Zovirax seems to stop progression of the rash and prevent visceral
complications.
29.
30. German Measles/Rubella
acute, mildly contagious viral disease that causes a distinctive 3-
day rash and swollen glands. It starts on the face and spreads
rapidly, often covering the trunk, arms, and legs within hours. A
slight fever may accompany the rash, but this usually disappears
after the first day of the rash.
It occurs most often among children ages 5 to 9, adolescents, and
young adults.
If pregnant woman gets this infection-especially during the first
trimester-her baby may have severe birth defects.
German measles virus is spread through contact with the blood,
urine, stools, or nasal or throat secretions of an infected person,
and possibly from contact with contaminated articles of clothing
Treatment consists of aspirin for fever and joint pain. The person
should be isolated until the rash disappears.
To prevent the measles, people can be immunized with live virus
vaccine RA 27/3
31.
32. Leprosy/Hansen´s disease
chronic systemic (generalized) infection characterized by
progressive skin lesions
the lepromatous form of the disease may lead to blindness and
deformities
it is caused by Mycobacterium leprae, a bacterium that attacks
skin tissue and peripheral nerves
continous close contact is needed to transmit it.
9 out of 10 persons have natural immunity to it
Transmission occurs through airborne respiratory droplets or
by inoculation through skin breaks
The incubation period is unusually long – 6 months to 8 years
It is prevalent in the underdeveloped areas in Asia especially
India nad China, Africa, South America and the islands of the
Carribean and Pacific.
33. It occurs in three distinct forms:
Lepromatous leprosy, the most serious
type, causes damage to the upper
respiratory tract, eyes, and testicles, as well
as the nerves and skin.
Tuberculoid leprosy affects peripheral
nerves and sometimes the surrounding
skin, especially on the face, arms, legs, and
buttocks.
Borderline (dimorphous) leprosy has
characteristics of both lepromatous and
tuberculoid leprosies. Skin lesions in this
type of leprosy are diffuse and poorly
defined.
34. caused by a virus called paramyxovirus. It
spread by direct contact or through the
air. The virus enters the body through
Koplik´s spots, the hallmark of the
disease, appear. These spots look like tiny,
bluish gray specks surrounded by a red
halo. They appear inside the mouth
opposite the molars and occasionally
bleed.
Severe infection may lead to seconadary
infection and to autoimmune reaction or
organ invasion by the virus, resulting in
ear infection, pneumonia, and brain
inflammation.the upper respiratory tract
37. Eye proteins have germ-killing power, could lead to new
antimicrobial drugs, study finds
discovery by UC Berkeley researchers
The small fragments of keratin protein in the eye play a key
role in warding off pathogens.
These new small proteins in the study were derived from
cytokeratin 6A, one of the filament proteins that connect to
form a mesh throughout the cytoplasm of epithelial cells.
The cytokeratins were primarily structural proteins, but the
study of the researchers shows that these fragments of
keratin also have microbe-fighting capabilities
Cytokeratin 6A can be found in the epithelial cells of the
human cornea as well as in skin, hair and nails. These are all
areas of the body that are constantly exposed to microbes, so
it makes sense that they would be part of the body’s defense
These keratin fragments are relatively easy to manufacture,
making them good candidates for low-cost therapeutics
38. Defense Mechanisms in the Eye
Blink Reflex
It is a mechanical defense against particles in the air or trauma.
Eyelashes and the sensitive cornea both participate in this
reflex. Tears, debris, allergens, microbes, etc. are moved over to
the lacrimal excretory system with the motion from the eyelid.
Barriers
The orbital septum, cornea and conjunctiva all provide a
protective barrier against pathogens. The orbit and the eyelid
are separated into preseptal and postseptal spaces by the orbital
septum which creates a physical barrier against infections. The
various layers of the cornea limit permeability of items into the
eye. Also, native flora of the lids and mucosal surface limit
possible pathogenic colonization.
39. Tears
Tears provide a mechanical defense via flushing of foreign
particles from the surface of the eye and transporting
antimicrobial agents to the surface as defensive measures.
Immune Response
The cornea, due to lack of a vascular system, contains limited
immune defenses. Immune defenses are provided by
Langerhans cells and immunoglobulins. Langerhans cells
modify B and T cell in the cornea while glycocalyx , a
transmembrane mucin made up of a mucin-like glycoprotein
adds protection by preventing adhesion of foreign molecules to
the surface of the eye.
Leukocyte Defense
Leukocytes consume and destroy microorganisms via and
oxygen-dependent pathway and an oxygen-independent
pathway (utilizes defensins which are peptides that have a
broad range of antibacterial, antifungal, and some antiviral).
40. Inflammation of the Cornea/Keratitis
inflammation of the cornea produces cloudy areas in
the corneal tissue, mild irritation, tearing and
sensitivity to light
It results from infection by herpes simplex virus type I
(known as dendritic inflammation of the cornea)or
from congenital syphilis (known as interstitial
inflammation of the cornea). Less commonly, it stems
from bacterial or fungal infections.
Herplex eyedrops and ointment or Vira-A Ophthalmic
ointment
41. Stye/Hordeolum
It is a localized red, swollen, and tender
abscess of the eyelid glands. A pus-filled
discharge is typically present. It can occur
outside or inside the eye.
It is caused by infection of the eyelid glands
by Staphylococcus bacteria.
Consists of warm compresses applied for 10
to 15 minutes, 4 times a day, for up to 4 days
to promote drainage of the abscess and to
relieve pain and inflammation.
Drug therapy includes a topical
sulfonamide or antibiotic eye drops or
ointment. If conservative treatment fails,
incision and drainage may be necessary.
43. Encephalitis
In this disorder, the person develops severe inflammation and
swelling of the brain tissue.
Usually the acute illness begins with sudden onset of fever,
headache, and vomiting. Later, the person may experience
neck and back stiffness. Many symptoms may result from
physiologic changes to the brain and nervous system:
drowsiness, coma, paralysis, seizures, inability to coordinate
voluntary muscular movements and, possibly psychotic
behavior. After the acute phase of illness, coma may persist
for days or weeks.
The most common causes of acute viral encephalitis
are rabies virus,Herpes simplex, poliovirus, measles virus
Bacterial causes could be Streptococci, staphylococci and
certain Gram-negative bacilli
The antiviral drug Avirax is effective in treating encephalitis
caused by herpesvirus, but it does not work against
encephalitis caused by other virus
44.
45. Inflammation of the Spinal Cord/Myelitis/acute
transverse myelitis
It could be caused by infectious diseases such as measles or
pneumonia, syphilis or hematomyelia. It may be result from
poliovirus, herpes zoster, herpesvirus B, or rabies virus.
No effective treatment exists. Some people with
postinfectious or multiple sclerosis-induced spinal cord
inflammation have received corticosteroid therapy, but its
benefits aren´t clear.
46. Inflammation of the spinal cord can result
from several diseases:
Poliomyelitis affects the cord´s gray mater
and produces motor dysfunction
leukomyelitis affects only the white mater
and produces sensory dysfunction
Acute transverse spinal cord inflammation
which affects the entire thickness of the
spinal cord, produces both motor and
sensory dysfunctions. May develop flaccid
paralysis of the legs (sometimes beginning
in just one leg)
47. Meningitis
The brain and the spinal cord meninges become inflamed
usually as a result of bacterial infection. Such inflammation
may involve all three meningeal membranes: the dura mater,
the arachnoid, and the pia mater.
Aseptic meningitis results from a virus, such as an
enterovirus (most common), arbovirus, herpes simplex virus,
mumps virus, or lymphocytic choriomeningitis virus.
Syndrome starts suddenly, with fever of up to 104oC (40oC),
drowsiness, confusion, and neck or spine stiffness, which is
slight at first. Other symptoms include headache, nausea,
vomiting, stomach pain, vague chest pain, and sore throat.
The person receives appropriate antibiotic therapy and
vigorous supportive care. Such antibiotic include Bicillin,
Omnipen, or Nafcil.
48.
49. Rabies
It is an acute infection of the brain and spinal cord.
It is caused by ribonucleic acid virus. Generally, the virus is
transmitted to a human through the bite of an infected animal.
The virus proliferates in muscle cells at the bite site, then spreads
along the affected nerve to the nervous system and multiplies in the
brain.
Finally, it moves through the nerves into other tissues, including the
salivary glands.
The risk of developing rabies depends on the location of the bite.
For instance, if you´re bitten on the face is 60%; on the arm, 15%
to 40% and on the leg, about 10%.
