Transcript Diseases of the Skin

Diseases of the Skin
Skin
• Healthy, intact skin keeps microbes out of the
body
• Sebum, sweat effect bacteria
• Skin cells are keratinized
• Dead skin cells are a food source for some
bacteria
• Microbes like it warm and moist
Normal skin bacteria
• Staphylococcus G+
• Micrococcus G+
• Propionibacterium G+
Bacterial Skin Infections
Acne
• Propionibacterium acnes (primarily)
• Many different types
– Anaerobic
– Uses sebum as food source
– Affects 85% of teens
– Many causes: hormones, stress, sweat, genetics
– Not transmissible
Impetigo
Staphylococcus aureus (children)
Streptococcus pyogenes (adults)
• Thin walled vesicles rupture and crust
• Always carry risk of infection in the blood or
below epidermis
Scalded Skin Syndrome
• Staphylococcus aureus
• Produces an endotoxin that causes the skin to
peel off
• Frequently a complication of Staphylococcus
infection
Toxic Shock Syndrome
• Staphylococcus aureus
• “Sunburn” rash
• Toxin causes capillaries to become permeable,
causing a life threatening drop in blood
pressure
• Originally liked to highly absorbent tampons in
the 1980’s
Nectotizing Fascitiis
• Streptococcus aureus
• When a bacterial infection spreads deeper
into the skin.
• Mortality is 40%
• Hyperbaric chamber, surgical removal
Dermatitis
• Pseudomonas
• Found in soil, water
• Rash associated with swimming pools, hot
tubs, saunas
• Nosocomial
• Also causes Otitis media
Viral Skin Infections
Chicken pox
• Varicella virus
• Highly contagious
• Mild childhood disease, 95% of population has
been exposed,100 deaths per year
• Spread through the respiratory droplet
• Vaccine since 1995 (live, attenuated)
Shingles
•
•
•
•
Another manifestation of chicken pox
Virus is latent in the dorsal root ganglion
Reactivated by stress, low immune system capability
Virus moves along peripheral nerves (unilateral) where it
causes blister rash
• Communicable – can cause chicken pox in persons that have
not had the disease
Smallpox
• Variola virus
• 80% of the population had disease during the
middle ages
• Transmitted by respiratory droplet
• First human disease to be eradicated
Reyes Syndrome
• Occasional, severe complication of a viral
infection
• A few days after original infection – vomiting,
brain dysfunction, coma, death
• Associated with aspirin
Cold sores
• Herpes simplex virus, type 1 (HSV-1)
• Provocative stimuli include fever, UV radiation, stress or
mechanical injury
• Prodromal stage
• The virus is reactivated and migrates to the surface where it
causes lesions
• Spread by direct contact, droplet transmission
Warts
• Human papillomavirus
•
•
•
•
Plantar warts – painful, deep, feet
Common/seed warts – painless, flat, fingers
Flat warts – smooth, develop everywhere
Genital warts – common STD
• Wart is not contagious but the virus can be
passed to another individual
Rubeola (measles virus)
Big red disease, 7- day measles
• Transmitted by respiratory droplet
• Macular rash
• Incubation is 2-3 weeks so subject is infectious
before the rash is visible
• Lesions in the mouth called Koplik’s Spots –
red spots with white centers
Rubella
3-day, German Measles, Little red measles
• Milder measles disease
• Humans are the only reservoir
• Causes severe birth defects if infected in
first 3 months
• MMR vaccine
Fungal Skin Infections
Tinea
•
•
•
•
•
Tinea capsis, ringworm
Tinea cruris, jock itch
Tinea pedis, athlete’s foot
Tinea unguinum, nail fungus
Tinea versicolor, a skin rash
Candida albicans
• Candidiasis or thrush
• Vaginal infection
• Found anywhere there is damp skin, normally
suppressed by local flora (bacteria)
Parasites of the Skin
Eyebrow mite
• Dermodex follicularum
• Lives in the eyebrows and eyelashes
Head lice
• Insect
• Predominantly found in Anglo hair
• Very contagious, direct or indirect
Scabies
• Insect
• Burrow into the skin and cause intense itching
• Very contagious, direct or indirect
Diseases of the Nervous System
Nervous System Structure
• Central Nervous system
– Brain
– Spinal cord
• Peripheral Nervous system
– Nerves
Diseases of the eye
• Conjunctivitis
– Inflammation of the conjunctiva or Pinkeye
– Haemophilus influenzae, Adenovirus
– Contact lenses
• Gonorrheal ophthalmia
– Neisseria gonorrhoeae
– Silver nitrate, antibiotics
• Trachoma
– Chlamydia trachomatis
– Can lead to permanent scarring, blindness
Bacterial Nervous Disease
Meningitis
• Can be caused by virus (most common),
fungus, protozoa, bacteria (most deadly)
• Microbe enters through lungs
Meningitis
• Normal throat bacterial inhabitants
• Haemophilus influenzae
– Also causes pneumonia, otitis media, epiglottitis
– Hib vaccine
• Neisseria meningitidis
– Meningitis vaccine for military, college populations
• Streptococcus pneumoniae
– Leading cause of bacterial meningitis
– New vaccine also decreases the amount of otitis media
Tetanus
• Clostridium tetani
– Obligate anaerobe, endospore forming, G+
– Produces tetanospasmin (neurotoxin) blocks
the relaxation pathway of muscles
– Jaw (lockjaw), back muscles, respiratory
muscles
• Neonatal Tetanus
– Most often the result of infected umbilical
stump where the site has been covered with
mud.
Botulism
• Obligate anaerobe, endospore forming, G+
• Neurotoxin produced by Clostridium
botulinum blocks release of acetylcholine
• Occurs most often in home-canned foods
• Also called the ‘sausage disease’
• Infant Botulism or Floppy Baby Syndrome
– Often transmitted by contaminated honey
Viral Nervous Disease
Poliomyelitis
• Seen in areas with poor sanitary conditions
• Caused by the polio virus, transmitted by ingestion of
contaminated water
– Multiplies in throat, tonsils, viremia
– Enters the CNS, affects the motor nerve cells where it replicates
and kills the nerves, causing paralysis
• Causes paralysis of the motor nerves less than 1% of the
cases
Timeline
• 1908 virus discovered
• 1938 March of dimes
• 1955 Salk IPV clinical trials, 90% effective
– Killed virus
• 1957 Sabin OPV, tested abroad
– Attenuated virus
– Licensed in 1962 and became preferred vaccine as it has
higher effectiveness
– Virus can back-mutate and spread the disease
• 1970 Return to Salk using Salk vaccine
• 1978 New, improved vaccine
Rabies
• A specific type of encephalitis
• uninique bullet shaped virus
• Almost always fatal
• Uniquely long incubation period
– Localizes in muscle, connective tissues
– Travels slowly along peripheral nerves to CNS
• 90% cases caused by skunk, raccoon, bat, fox
• Vaccination after a bite is determined by
presence of rabies in the area
– A series of antirabies vaccine + immune globulin
antibodies
– 5 to 6 injections over 28 days
• Pre-exposure vaccine available
Encephalitis
• Arbovirus
• Chills, headache, fever, mental confusion,
coma, death can occur
•
•
•
•
Eastern Equine Encephalitis
Western Equine Encephalitis
St. Louis encephalitis
West Nile virus
Circulatory & Lymph Diseases
Circulatory System
• Blood
– Formed elements, plasma
• Vessels, capillaries and heart
• Lymph system
Hemolysis
• β-hemolysis on blood agar is a clear window
• α-hemolysis on blood agar is green
• Hemolysis – bacteria use the RBC’s for iron
• Transferrins bind extra iron in the bloodstream
• Staphalycoccus aureus
Terminology
• Septicemia
• Lymphangitits
• G+ sepsis
• G- sepsis
Bacterial Circulatory Disease
Gangrene
• Clostridium perfringes – anaerobic, produces
toxins
• Blood supply to tissue is interrupted causing
ischemia (anaerobic wound condition).
• Leads to tissue death or necrosis
• Hyperbaric chamber, amputation
Rheumatic Fever
• Streptococcus pyogenes
• Causes arthritis-like joint inflammation,
possible heart valve damage
Rocky Mountain Spotted Fever
• Rickettsia rickettsi
• Passed by tick vector
• Characteristic rash on body, soles of feet and
hands
• Prevalent in Southeastern and Southern USA,
not in Rocky Mountains
Lyme Disease
• Borrelia burgdorfei - a spirochete
• Vector is a tick, reservoir is field mouse
• First identified in 1975 in Lyme county, Connecticut
• Diagnosed as rheumatoid arthritis
• Seasonal occurrence
• Bulls eye rash, flulike symptoms
Viral Cardiovascular Disease
Epstein Barr Virus
• Mononucleosis, Burkett’s Lymphoma, Chronic
Fatigue Syndrome
• Virus replicates in salivary glands
• Spread by droplet
• Causes Lyphocytes with unusual nuclei to
proliferate
• In the US infection happens more frequently
in young adulthood
Parasitic Cardiovascular Disease
Malaria
• Plasmodium, a parasite with four
separate species
– Plasmodium falciparum is the most
dangerous
• Anopheles mosquito (female) – vector
• Associated with Sickle Cell Anemia
Epidemiology
• Prevalent in tropical and subtropical climates
• 2 million victims yearly, mostly children
• Medications are less effective, parasite is
resistant
Swimmer’s Itch
• A form of dermatitis caused by an allergic
reaction to a parasite picked up in a
freshwater swimming area.
• Parasite is normally a snail parasite, carried by
domestic waterfowl
• Short term infection, itchy
Respiratory Disease
Diseases of the Respiratory System
• Separated into upper and lower respiratory
diseases
Normal Microbiota
• Upper – many potentially pathogenic
microbes
• Lower – sterile
• Pharyngitis, laryngitis, tonsillitis, sinusitis,
epiglottitis
Bacterial Respiratory Disease
Strep Throat
• Streptococcus pyogenes
• Inflammation, fever, tonsillitis, swollen lymph
glands, otitis media
– Penicillin is drug of choice
Scarlet Fever
• Streptococcus pyogenes, which causes strep
throat can also develop into Scarlet fever
– Toxin is result of bacteriophage incorporating
information into the bacterial chromosome
– Causes red skin rash, swollen spotted tongue
Pertussis or Whooping cough
• Bordatella pertussis
• Attach to ciliated cells in trachea, Produces toxins which
destroy ciliary escalator movement and violent coughing
Pneumonia
• Bacterial, viral, protozoan, fungi, etc.
– Lobar, bronchial, pleural
• Streptococcus pneumoniae – typical bacterial
pneumonia
– Alveoli fill with RBC, WBC, fluid – can enter blood
stream and spread
– Vaccine is made from 23 different types of pneumonia capsules
•
•
•
•
•
Mycoplasmal pneumonia, walking pneumonia
Legionnaire’s disease
Pneumocystis pneumonia
Viral pneumonia
Respiratory Syncytial virus (RSV)
Otitis media
• Occurs frequently in children under 2 years
because the Eustachian tube is shorter.
• S. pneumoniae causes the majority of these
middle ear infections
• Can easily progress to meningitis
• Vaccine is available
– Older vaccine made of 23 capsular antigens
suggested for older adults
– Newer conjugate vaccine for infants
Tuberculosis
• Mycobacterium tuberculosis
• 20 hour generation time
• Often resistant to antimicrobial disinfectants
and antiseptics
• TB test, chest x-ray
Tuberculin sensitivity Testing
• Used to screen school children, healthcare
workers, public employees.
• A positive reaction is reliable evidence that
the individual has been exposed or has had
TB.
• An individual with a positive reaction will be
asked to have a chest x ray.
Diphtheria
• Corynebacterium diphtheriae
• G+, endospore-forming, rod
– Sore throat, fever, malaise
– Tough grayish membrane forms at back of throat
– Can produce exotoxin when lysogenized by
bacteriophage, toxin interferes with protein
synthesis and often causes death
• transduction
Viral Respiratory Disease
Common Cold
• Rhino virus, +110 types, Corona virus
• Accumulate immunity for each type
• Can be caused by a single virus
Influenza
• Influenza virus A, B, C (A can cause pandemics)
– Also cause influenza in pigs, horses, mammals, birds
• Spikes mutate year to year
– No single vaccine works, usually a combination of at
least three
• 1918 – 1919 Single highest demographic shock of human race in 6
months
Fungal Respiratory Disease
Histoplasmosis or Ohio Valley Fever
• Histoplasma capsulatum
• An important disease around as long as man has practiced
agriculture
• Dimorphic
• Endemic on all continents except Australia
• Moist soils high in nitrogen, especially where bird/bat guano
• 500,000 cases/year and only few deaths, mostly adult males
Infection and Pathogenesis
• Inhalation of spores into the depths of
the lung, spores establish infection that is
asymptomatic.
• Aches, pains, coughing, fever, night
sweats, weight loss
• Most serious forms occur in patients that
are immunocompromised
Digestive Disease
Anatomy
• Gastrointestinal tract – one long tube through
the body – mouth, pharynx, esophagus,
stomach, small and large intestine
– All produce large amounts of mucous
• Accessory structures - teeth, tongue, salivary
glands, liver, gall bladder, pancreas
Microbial Inhabitants
• Mouth has millions of bacteria in each mL. of
saliva
• Stomach, small interesting – acidic pH – few
microbes
• Large intestine – millions of bacteria, mostly
anaerobic or facultative
Bacterial Digestive Disease
Tooth Decay
• Dental Caries
• Teeth are hard and do not shed surface cells so
bacteria can attach easily
• Oral bacteria convert sucrose to fructose (lactic acid
which attacks the enamel surface) and glucose
(dextrose which is sticky)
• Streptococcus mutans
• Lactobacillus
• Bacteria do not adhere to clean teeth
• One of the most common infections today
• If unattended can cause abscesses
• Scarce before the 17th century
• Disease started with the introduction of table
sugar (sucrose)
• Sugar alcohols in sugarless gum are
preventative
Gum Disease
• Periodontal disease – inflammation and
degeneration of the structures that support
the teeth
• Characterized by bleeding gums
• Gingivitis
Food Contamination
• Infection – pathogen enters the GI tract and
multiplies.
– Characterized by delay
• Intoxication – ingestion of toxins from bacteria
– Characterized by sudden appearance of symptoms
• Dysentery – diarrhea and blood in the stool
Food Contamination
•
•
•
•
Staphalococcus aureus
Enterotoxin
Normally inhabits the nasal passages
Can grow in things prepared in advance and
not kept chilled
• Toxin not destroyed when food is reheated
Food Contamination
•
•
•
•
•
Shigella
Produces shiga toxin – destroys mucosal tissue
Severe diarrhea, “Travelers Diarrhea”
Oral fecal route of contamination
Found in vegetables fertilized with human
waste
Food Contamination
• Salmonella
• Normal inhabitant of the human, animal
intestinal tract
• Can pass through the mucosa into lymph and
cardiovascular systems, can affect many
organs
• Poultry, eggs, pets
Food Contamination
• E. coli
• Generally regarded as a lab pet
• Pathogenic forms have special fimbrae that
allow them to bind to cells
• Produces enterotoxin which causes watery
diarrhea
• Found in cattle intestines, can be spread to
meat
Ulcers
• Helicobacter pylori
• Peptic ulcer disease – bacteria discovered as a
cause in 1982
• pH in stomach is 2.0, cells have a protective
layer to prevent inflammation
• Bacteria disrupts this layer, allowing damage
to the tissue
• Connection to type ) blood?
Viral Digestive Disease
Hepatitis
• Inflammation of the liver
• Caused by 5 different viruses: A, B, C, D, E
Hepatitis A
• Transmitted by the oral fecal route
• Greatest danger is before symptoms are
visible so food handlers can infect others
before they know they have the disease
• Inactive virus vaccine available called gamma
globulins
Hepatitis B
•
•
•
•
Transmitted through blood or sexually
Difficult to differentiate between A and B
Vaccine available (grown in yeast)
90% cure rate, 10% chronic carrier
Hepatitis C
• Identified in 1960
• Transmitted by blood
• Aprox. 70 days between infection and
detection
• Called the Silent Epidemic, killing more in the
US than AIDS
• High % develop cirrhosis of the liver, liver
cancer
• α Interferon
Parasitic Digestive Disease
Roundworm
• Ascaris lumbricoides
• Eggs ingested - hatch into larvae in the small
intestine - burrow to lung or throat where are
swallowed - move to the small intestine where
they mature and lay eggs - passed through
feces and ingested by another host
Tapeworm
• Consumption of undercooked beef, pork, fish
• Adult beef tapeworm can live 25 years and
grow to 6 m. in length in human intestines
• Eggs are released with feces, stick to the grass
and are eaten by animals.
• Larvae lodge in muscle and are eaten by
humans.
• Few symptoms – bloating, belching
Pinworms
• Enterobius
• Female migrates out the anus at night to lay
eggs
• Severe anal itching
• Entire households can become infested
Hookworms
• Attaches to the intestinal wall and feeds on
blood and tissues
• Requires bare skin contact to spread
• Wearing shoes has stopped the spread.
Trichinosis
• Small roundworm
• Transmitted by eating raw meat, especially
pork or other animals that eat garbage
• Larvae encyst in animal muscle – cyst wall is
digested in stomach – larvae invade tissue and
move to eye muscle, diaphragm
Diseases of the Urinary and
Reproductive Systems
Anatomy
• Urethra – bladder – ureter – kidneys
• 30 separate STD’s
• Most can be prevented with condom use
• Viral diseases have no cure
• Female
– Urethra conveys only urine
– Opening between ovary and uterine tube
– Urethra is short and close to the rectum
– Bacterial population is influenced by hormone
levels
– Sores that are indicative of disease often appear
only on the cervix
• Male
– Urethra conveys urine and sperm
– Infection is often more visible
Fungal Diseases
Candidiasis
• Candida albicans – yeast
• Opportunistic infection
• NGU in males
• Candidiasis in females
Viral Reproductive Disease
Genital Herpes
• Herpes Simplex Virus 2 (HSV-2)
• Incubation 1wk., burning sensation and vesicles,
painful walking and urination
• Disease can be transmitted without the presence of
vesicles
• HERPES IS FOREVER
• Condoms do not protect you against Herpes
• Causes serious fetal damage
Genital Warts
• Human Papilloma virus
• Greatest danger is connection to cancer
Bacterial Urinary, Reproductive
Disease
Urinary Tract Infection
• Almost always bacterial
• E. coli, Stpahyalococcus
• Why??
•
•
•
•
•
Dystitis
Urethritis
Polynepritis
Dysuria
Pyruia
Non-Gonococcal Urethritis
• A general term for any inflammation of the
urethra not caused by Neisseria gonorrheaeae
• Chlamydia trachomatis - most prevalent STD
in the US
• Symptoms
– Male – epididymis inflammation, mild
– Female – asymptomatic, leads to PID
Pelvic Inflammatory Disease
• General term for an extensive bacterial
infection of the female pelvic organs
• Causes pain, infertility
• 60% of patients with PID have three or more
episodes
Syphilis
• Treponema palladium – the teflon pathogen
• Lacks enzymes to build complex molecules
that the bacteria needs to survive outside the
host
• Three stages
• Stage 1
– Initial hard based sore called a chancre
– Fluid is highly infectious
– Not seen in female because it is on the cervix
• Stage 2
– Characterized by a skin rash, widely distributed
– Lesions are contagious
– Disease now enters latent period where there are
no symptoms
– Congenital syphilis – transmitted across the
placenta resulting in severe fetal damage
• Stage 3
– Less than 50% of cases reach this stage
– Lesions or gummas form on affected organs
– Not usually harmful but it depends on the location
of the lesion. Can cause tissue death
Gonorrhea
• Neisseria gonorrhoeae
• “flow of semen”
• Bacteria attaches to the epithelial cell walls via
fimbrae
• Inflammatory reaction of the body results in
WBC’s moving to the site, pus forms
• One exposure results in the disease 35% in
males, 90% in females
Male Symptoms
• Painful urination, discharge
• Scarred urethra if ignored
• Sterility results if infection reaches the testes
or when ductus is blocked
• Most often identified and antibiotics are given
Female Symptoms
•
•
•
•
Females unaware of the infection
Cervix is infected
Pain from PID (later)
Can become systemic – meningitis, eye
infection, gonorrheal arthritis
Caution
• Can be acquired by any sort of sexual contact
• Antibiotic resistance is increasing
• Coinfections are frequent
• The bacteria cannot live outside the human
body