Diseases of the Skin Skin Healthy intact 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 m. L. of saliva • Stomach, small interesting – acidic p. H – 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 17 th 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 • p. H 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 1 wk. , 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 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