Transcript LOCAL LESIONS IN RESPONSE TO BACTERIAL INFECTIONS

Very few microbes are
always pathogenic
Many microbes are
potentially pathogenic
Most microbes are
never pathogenic
A lesion anywhere on the
body that does not spread.
An
infection is the detrimental
of a host
by a
foreign
The infecting organism, or
interferes with the normal
functioning of the host and can lead
to
,
loss of
an infected limb, and even
Symptoms of bacterial infection are
localized Redness, Heat, Swelling and
 Includes local pain, pain that is in a
specific part of the body.
 For example, if you get cut and the cut
gets infected with a bacterium, it will
be painful right where the infection is.
If you have a sore throat and the
infection is bacterial, one side of the
throat is often more sore than the other.
An ear infection is usually bacterial if
one ear hurts and the other doesn't. An
infection that produces pus is always
bacterial.

Impetigo is a common bacterial infection of the upper
layers of the skin caused by Streptococcus pyogenes
and Staphylococcus aureus. It is highly contagious and
usually treated with a topical antibiotic.
 Impetigo tends to occur in areas of minor breaks in the
skin such as insect bites, cuts, or abrasions. Impetigo
can also occur in breaks in the skin caused by skin
conditions such as scabies, herpes, chickenpox.
 Often people harbor the Staphylococcus bacteria inside
their nose and don't even know it because it does not
cause an infection inside the nose. However, direct
contact with infected nasal fluid can infect other parts
of the body or other people. The following are common
contributing factors: Warm, humid climate or
environment

 Dental
caries, also known as
or cavity, is a disease wherein bacterial
processes damage hard tooth structure
(enamel, dentin, )
 These tissues progressively break down,
producing dental caries (cavities, holes in
the teeth).
 Two groups of bacteria are responsible
for initiating caries: Streptococcus
mutans and Lactobacillus.
 If left untreated, the disease can lead to
pain, tooth loss, infection, and, in severe
cases,
 Tooth
decay is caused by specific types of acidproducing bacteria that cause damage in the presence
of fermentable carbohydrates such as sucrose,
fructose, and glucose.
 The
mineral content of teeth is sensitive to increases
in acidity from the production of lactic acid
 A person
experiencing caries may not be aware of the
disease. The earliest sign of a new carious lesion is the
appearance of a chalky white spot on the surface of
the tooth, indicating an area of demineralization of
enamel. This is referred to as incipient decay.
 As
the lesion continues to demineralize, it can turn
brown but will eventually turn into a cavitation
("cavity").
 Before the cavity forms, the process is reversible,
but once a cavity forms, the lost tooth structure
cannot be regenerated
 A lesion which appears brown and shiny suggests
dental caries was once present but the
demineralization process has stopped, leaving a
stain.
 A brown spot which is dull in appearance is
probably a sign of active caries.
 is
a chronic bacterial
infection caused by Treponema
pertenue,
 Yaws is contagious via direct skin
contact with an infective skin
lesion.
 The bacteria typically gains entry
through a cut, bite or
scratch. Yaws mainly infects your
skin, bones and joints.
 Yaws
bacteria gains entry, an itchy, raspberry
looking skin lesion develops at the site of entry.
This typically painless lesion is known as the
and this symptom may persist for
months. Any nearby lymph nodes may swell as
well.
 If the bacteria is left untreated, more skin infection
lesions may develop shortly after the mother yaw
heals. These sores are highly infectious.
 Over several years, the lesions on your skin and
bones can cause severe and permanent destruction.
Yaws causes deformities of legs, nose, palate and
upper jaw. But most often, yaws symptoms are
limited to
 Staphylococcal
scalded skin
syndrome (SSSS), also called
Lyell's disease or toxic epidermal
necrolysis,
 starts as a localized lesion,
followed by widespread erythema
and exfoliation of the skin.
 This disorder is caused by phage
group II staphylococci which
elaborate an epidermolytic toxin.
The disease is more common in
infants than in adults.
 The
most superficial form of skin infection is
staphylococcal folliculitis, manifested by minute
erythematous follicular pustules without
involvement of the surrounding skin.
 The scalp and extremities are favorite sites. Gramnegative folliculitis occurs mainly as a
superinfection in acne vulgaris patients receiving
long-term, systemic antibiotic therapy.
 These pustules are often clustered around the
nose. The agent is found in the nostril and the
pustules.
 The
primary lesion is a white to yellow follicular
pustule, flat or domed. Gram stain of pus reveals
numerous intracellular and extracellular Grampositive pleomorphic rods.
 The lesions are more common in men than in
women. The process may start at the age when
acne usually appears, yet most cases occur years
late
 Pitted
keratolysis is a superficial infection
of the plantar surface, producing a
punched-out appearance.
 The pits may coalesce into irregularly
shaped areas of superficial erosion.
 The pits are produced by a lytic process
that spreads peripherally. The areas most
often infected are the heels, the ball of the
foot, the volar pads, and the toes.
Humidity and high temperature are
frequent aggravating factors. Grampositive coryneform bacteria have been
isolated from the lesions.
A common disorder, occurs most often in
the beard area of black people who shave.
 The characteristic lesions are usually
erythematous papules or, less commonly,
pustules containing buried hairs.
 This occurs when a strongly curved hair
emerging from curved hair follicles
reenters the skin to produce an ingrown
hair.
 Gram-positive microorganisms that
belong to the resident flora are associated
with this disorder.

 Localized
skin tuberculosis may follow inoculation
of Mycobacterium tuberculosis into a wound in
individuals with no previous immunologic
experience with the disease.
 The course starts as an inflammatory nodule
(chancre) and is accompanied by regional
lymphangitis and lymphadenitis.
 The course of the disease depends on the patient's
resistance and the effectiveness of treatment. In an
immune or partially immune host, two major
groups of skin lesions are distinguished:
and
.
.
Skin Tuberculosis
 Many
cases of M marinum skin
disease occur in children and
adolescents who have a history of
using swimming pools or cleaning
fish tanks.
 Often, there is a history of trauma,
but even in the absence of trauma the
lesions appear frequently on the sites
most exposed to injury.
 The usually solitary lesions are
tuberculoid granulomata that rarely
show acid-fast organisms. The skin
tuberculin test is positive.
Lesions in M ulcerans skin disease occur
most often on the arms or legs and
occasionally elsewhere, but not on the
palms or soles.
 Most patients have a single, painless
cutaneous ulcer with characteristic
undermined edges.
 Geographic association of the disease
with swamps and watercourses has been
reported. In some tropical areas, chronic
ulcers caused by this organism are
common.
 In scrofuloderma, tuberculosis of lymph
nodes or bones is extended into the skin,
resulting in the development of ulcers.
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Actinomyces israelii usually is the agent of human
actinomycosis.
The characteristic appearance of the lesion is a hard, red,
slowly developing swelling. The hard masses soften and
eventually drain, forming chronic sinus tracts with little
tendency to heal. The sinus tracts discharge purulent
material containing “sulfur” granules.
In about 50 percent of cases, the initial lesion is
cervicofacial, involving the tissues of the face, neck, tongue,
and mandible.
About 20 percent of cases show thoracic actinomycosis,
which may result from direct extension of the disease from
the neck or from the abdomen or as a primary infection
from oral aspiration of the organism.
In abdominal actinomycosis, the primary lesion is in the
cecum, the appendix, or the pelvic organs.