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Bacteria Disease
Folliculitis:
Signs and symptoms-
Pathogen and Virulence factors-
Pathogenesis-
Epidemiology-
Prevention-MRSA
- –Infection of hair follicle, becomes red, swollen, pus-filled
- –Staphylococcus –Salt-tolerant, tolerant of drying, solar radiation and heat –Two major genera – S. aureus and S. epidermidis- Virulence factors: 1) enzymes, 2) anti phagocytic factors, and 3) toxins
- –Via direct contact and via fomites–May grow down into hair follicle resulting in pus and spread, even to blood, causing bacteremia, and carried to heart, lungs and bones
- –S. epidermidis lives everywhere on your skin- S. aureus is not a permanent resident
- •Methicillin-resistant S.aureus(MRSA)–very common in hospitals–moving out into the community•Avoid MRSA by –Cleansing wounds carefully –Aseptic techniques –Appropriate use of antibiotics
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Bacterial Diseases
Necrotizing Fasciitis:“Flesh-eating bacteria”
Signs and symptoms-
Pathogen and Virulence factors-
Pathogenesis and Epidemiology-
Prevention
- –Very painful to touch, area feels hot, and sunburn-like rash may appear –Patients may get fevers, nausea, and become mentally confused
- –Mostly by Streptococcus pyogenes(group A) –Enzymes allows invasion of body tissue Exotoxins trigger overreaction by immune system
- –Enters through wounds to the skin, spreads rapidly along muscle fascia – several centimeters per hour, if reaches organs, 50% of patients die •Can enter through needlesticks, papercuts and other seemingly harmless wounds
- •Affected tissue must be removed completely and aggressively to prevent spread •Broad-spectrum antibiotics are given by IV
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Bacterial Diseases
Pseudomonas Infection:
Signs and symptoms-
Pathogen and Virulence factors-
- •The most commonly seen bacterium in burn patients–When it invades the bloodstream, it causes chills, fever, and shock –Produces a blue-green pigment - pyocyanin
- •Found in soil, decaying matter, almost everywhere–Grows in hot tubs, on sponges, washcloths, toilets, contact lens solution, dialysis machines, and respirators •Has many virulence factors –toxins and enzymes that cause tissue damage •Despite living everywhere, it rarely causes diseases!
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Bacterial Diseases
Gas Gangrene:
Pathogen and Virulence factors-
Pathogenesis and epidemiology-
Diagnosis, treatment and prevention
- –When tissue is wounded and becomes anaerobic, necrosis (death) sets in. If the wound has endospores of the anaerobe Clostridium perfringens, gas gangrene can develop –Produces many toxins that kill cells
- –Doesn’t infect healthy tissue – has to get there after a traumatic event, when tissue is dead –Despite therapeutic care, the mortality rate is beyond 40%
- –Seeing blackened, gaseous tissue is enough •And finding large G+ bacilli is confirmatory–Aggressive intervention is critical – surgically removing the dead tissue, giving large doses of antitoxin, and large doses of penicillin. Putting the patient in a hyperbaric chamber with oxygen may also work
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Viral Diseases
Herpes:
Signs and symptoms-
Pathogen and Virulence factors-
Pathogenesis-Epidemiology-
- –The virus produces painful, itchy skin lesions on the lips or genitalia. First outbreak, may have flu-like symptoms-Lesions recur in about 2/3 of patients because virus remains latent for life
- –Two viral species cause herpes: human herpesvirus 1 (HHV-1) and human herpesvirus 2 (HHV-2) •HHV-1 is usually associated with cold sores; HHV-2 with genital herpes
- –Even asymptomatic carriers can shed the HHV-2 genitally –HHV-1 infections occur most often during childhood; HHV-2 infections are acquired between the ages of 15-29 mostly- –Herpes is spread by contact with mucous membrane in either the mouth or genitals, and remain latent
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Viral Diseases
Warts:
Signs and symptoms-
Pathogen and Virulence factors-
Pathogenesis-
- –Canform anywhere, but often on fingers or toes•Plantar warts are deep in sole of foot and may hurt•Generally,warts do not hurt
- •Almost 60 strains of Papillomavirus cause warts
- •Unsightly, but most are harmless•Strong evidence that papillomaviruses can cause head, neck, anal, vaginal, penile, and oral cancers•Papillomaviruses of genital warts cause almost all cervical cancer
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Viral Diseases
Chickenpox and Shingles:
Signs and symptoms-
Pathogen-
Pathogenesis-
- –Fever,lesions on the back and trunk that spread to face, neck and limbs
- •varicella-zoster virus
- •highly infectious –Inhaled, enters mucous membranes, spreads to blood, lymph, nervous tissue–The virus may become latent in nerve tissue for years
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Viral Diseases
Rubella:
Signs and symptoms-
Epidemiology-
Diagnosis, treatment and prevention-
- •Commonly known in USA as German measles or three-day measles–Generally harmless in children causing a rash that lasts for 3 days –Infections in adults are more severe and may result in arthritis or encephalitis•Death of the fetus is common
- –Spreads through respiratory secretions and only infects humans •Patients shed virus for 2 weeks before and after rash
- –No treatment is available, but immunization is very effective at reducing the incidence of rubella in industrialized countries
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Viral Diseases
Measles:
Signs and symptoms-
Pathogen and Epidemiology-
Prevention-
- •One of the 5 classical childhood diseases that produce rashes–Also known as rubeola or red measles–Lesions called Koplik’s spots appear on the mucous membrane of the mouth- Rare complications include pneumonia, encephalitis and the extremely serious subacute sclerosing panencephalitis
- –Infects cells of respiratory tract, then spreads throughout the body –Most patients recover within 2-3 weeks, but 1-5% of children will die–Measles is highly contagious
- –A vaccine was introduced in 1963 –To eliminate measles requires a 2-dose immunization of at least 95% of the population
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Eukaryotic Pathogen Diseases:
Cutaneous mycoses (dermatophytoses):
Signs and symptoms-
Diagnoses, treatment and prevention-
- –Fungi that grow in skin are dermatophytoses
- –Often called ringworm–Athlete’s foot
- –Clinical observation is sufficient –Limited infections can be treated effectively with topical antifungal agents
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Eukaryotic Pathogen Diseases:
Leishmaniasis (caused by protozoan):
Signs and symptoms-
Pathogen and Virulence factors-
Pathogenesis and Epidemiology-
Diagnosis, treatment and prevention-
- –Several kinds, but visceral leishmaniasis is 100% fatal –Becoming increasingly problematic among AIDS patients
- –Leishmania is a protozoan hosted by wild dogs and domestic dogs and small rodents.Infected sand flies transmit the protozoan from animals to humans through bites–There are 21 species that can infect humans
- –Endemic in parts of the tropics and subtropics –2 million new cases occur each year, with 45,000 deaths
- –Most cases heal by themselves, but with scars–Prevention is about reducing reservoir host and sand fly populations- no vaccine
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Eukaryotic Pathogen Diseases:
Scabies (caused by mites- type of arachnid)
Signs and symptoms-
Pathogen and Virulence factors-
Pathogenesis and Epidemiology-
- –Intense itching, esp. at night, and a rash localized to infested areas of the skin
- –The mite Sarcoptes scabiei causes scabies
- –Female mites live in the skin and burrow to lay their eggs, producing itching blisters –Infested patients spread mites from one part of body to another, and pass the parasite to others by sharing clothing (you can get it at the mall in the dressing room!), towels, bedding, and by having sex.–300 million people develop scabies each year in the world; most are children under 15
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