19 Flashcards
Normal Flora - YEAST
(fungi)
Malassezia
Normal Flora - Bacteria
Staphylococcus, Micrococcus, Diptheroids
Normal Flora
- normally harmless
- CANNOT be completely removed thru cleansing
- may produce disease if they penetrate the epidermis or if the immune system is suppressed
Wounds
- trauma to any tissue of the body
- allows microbes to infect the deeper tissues
ex) cuts, scrapes, surgery, burns, bites
Folliculitis - signs + symptoms
- infection of the hair follicle
- aka pimple
- called a STY when it occurs at the eyelid base
- spread of infection into surrounding tissues can produce furuncles
- carbuncles occur when multiple furuncles grow together
Sty
folliculitis at the eyelid base
furuncles
- boils
- occurs when the infection spreads into surrounding tissues
carbuncles
when multiple furuncles grow together
folliculitis and its variations
pimple=folliculitis>furuncles>carbuncles
folliculitis is most commonly caused by…
staphylococcus
Staphylococcus
- gram pos bacteria
- facultative anaerobes
- cocci typically arranged in clusters
- tolerant of salt + desiccation
2 common types of Staphylococcus found on skin
1 Staphylococcus EPIDERMIS
2 Staphylococcus AUREUS
-differ by beta-lactamase production + toxin production
which is more pathogenic? staph. epidermis or staph aureus?
Staphylococcus aureus is more pathogenic
staph. epidermis vs staph aureus
Virulence Factors
COAGULASE [+ aureus][-epiderm]
B-Lactamase [90% of aureus][-epiderm]
Folliculitis - diagnosis
-isolation of gram-pos bacteria in grapelike clusters from PUS
Folliculitis - treatment
1 DICLOXACILLIN (semi synth penicillin) (drug of choice) 2 VANCOMYCIN used to treat resistant strains
Folliculitis - prevention
- hand antisepsis
- proper procedures in hospitals to minimize MRSA infections
Staphylococcal Scalded Skin Syndrome
[SSSS]
pathogen + virulence factors
- some Staph. AUREUS strains
- 1 or 2 different EXFOLIATIVE TOXINS cause SSSS
Staphylococcal Scalded Skin Syndrome
[SSSS]
pathogenesis
- no scarring bc dermis is unaffected
- death is rare but may occur due to secondary inifections
Staphylococcal Scalded Skin Syndrome
[SSSS]
epidemiology
- disease occurs PRIMARILY IN INFANTS
- transmitter by person-to-person spread of bacteria
Staphylococcal Scalded Skin Syndrome
[SSSS]
diagnosis
characteristic sloughing of skin
Staphylococcal Scalded Skin Syndrome
[SSSS]
treatment
- administer antimicrobial drugs
- widespread presence of S. aureus makes prevention difficult
what causes the skin to slough off in SSSS?
the release of EXFOLIATIVE TOXINS by staph. aureus
Impetigo [Pyoderma] + Erysipelas
pathogens + virulence factors
- most caused by S. AUREUS
- some caused by Streptococcus pyogenes
Streptococcus pyogenes
- gram pos coccus in chains
- similar virulence factors to staph. aureus:
- -M protein
- -hyaluronic acid
- -pyrogenic toxins
Impetigo [Pyoderma] + Erysipelas
pathogenesis
bacteria invade where skin is compromised
Impetigo [Pyoderma] + Erysipelas
epidemiology
- Impetigo [mostly childten]
- Erysipelas [mostly elderly]
-transmitted person-to-person contact or via formites
Impetigo [Pyoderma] + Erysipelas
diagnosis
-presence of vesicles is diagnosis for Impetigo
Impetigo [Pyoderma] + Erysipelas
treatment
penicillin + careful cleaning of infected areas
Impetigo [Pyoderma] + Erysipelas
prevention
proper hygiene + cleanliness
Necrotizing Fasciitis
[flesh eating bacteria]
pathogen + virulence factors
- most caused by Strep. pyogenes
- Exotoxin A + Streptolysin S are secreted
- various enzymes facilitate invasion of tissues
Necrotizing Fasciitis (flesh eating bacteria)
pathogenesis
Step. pyogenes enters thru breaks in skin
Necrotizing Fasciitis (flesh eating bacteria)
epidemiology
person-to-person
Necrotizing Fasciitis (flesh eating bacteria)
diagnosis
-difficult to diagnose early bc symptoms are nonspecific
Necrotizing Fasciitis (flesh eating bacteria)
treatment
1 clindamycin
2 Penicillin
Acne
pathogen + virulence factors
commonly caused by Propionibacterium acnes
Acne
epidemiology
- propionibacteria are normal bacteria
- typically begins in adolescence but may occur later
Acne
diagnosis
visual examination of skin
Acne
treatment
- antimicrobial drugs
- drugs that exfoliate dead skin cells
- ACCUTANE
- BLUE-LIGHT WAVELENGTH to destroy bacteria
Propionibacterium acnes
- gram pos
- ROD SHAPED diphtheroid
- normal flora
Pseudomonas
pathogen + virulence factors
Pseudomonas aeruginosa
-virulence factors: adhesins, toxins, + polysaccharide capsule
Pseudomonas
pathogenesis
- can occur in burn victims
- bacteria kills cells, destroys tissue, + triggers shock
- PYOCYANIN discoloration indicates massive infections
pyocyanin discoloration
greenish pigment seen in pseudomonas that indicates massive infection
Pseudomonas
epidemiology
- P. aeruginosa is not normal microbiota
- can cause infections throughout the body once inside
Pseudomonas aeruginosa
- found in soil, decaying matter, + moist environments
- not normal flora
- multidrug resistance
Pseudomonas
diagnosis
- difficult diagnosis
- pyocyanin discoloration
Pseudomonas
treatment
-difficult to treat due to multidrug resistance
Pseudomonas
prevention
-p. aeruginosa is widespread but infection usually doesn’t occur in healthy individuals
Cutaneous Anthrax
- caused by Bacillus anthracis
- occurs when anthrax spores get into the skin (cut + scrape)
- characterized by ESCHAR
- bioterrorism tool (spores in mail)
ESCHAR
black, painless, ulcer
Gas Gangrene
signs + symptoms
- blackening of infected skin + muscle
- presence of gas bubbles
Gas Gangrene
pathogens + virulence factors
caused by several CLOSTRIDIUM species
-C. perfringens
-
Gas Gangrene
pathogenesis + epidimiology
- traumatic even must introduce endospores into dead tissue
- mortality rate exceeds 40%
Gas Gangrene
diagnosis
appearance
Gas Gangrene
treatment + prevention
rapid treatment is crucial
- surgical removal of dead tissue
- administer ANTITOXIN + penicillin
- prevents w proper cleaning of wounds
Clostridium perfringens
endospore-forming bacteria
-vegetative cells secrete 11 toxins
Poxviruses
- smallpox aka VARIOLA
rare: orf, cowpox, monkeypox - first human disease eradicated globally
Poxviruses
signs + symptoms
-diseases progress through a series of stages
Poxviruses
pathogens + virulence factors
caused by ORTHOPOVIRUS aka VARIOLA virus
Poxviruses
pathogenesis
inhalation of virus
Poxviruses
epidemiology
-increase in monkeypox cases over the past decade
Poxviruses
diagnosis, treatment + prevention
- treatment is immediate vaccination
- vaccines discontinued in 80’s since eradicated
- bioterrorism scare
Herpes
signs + symptoms
- slow + spreading skin lesions
- recurrence of lesions is common
Herpes
pathogens + virulence factors
- caused by human herpesviruses 1 + 2
- virulence factors: various proteins produced
Herpes
pathogenesis
- painful lesions caused by inflammation + death cell
- causes fusions of cells to form SYNCYTIA
Herpes
epidemiology
- spread bw mucous membranes of mouth + genitals
- herpes infections in adult are not life threatening
Herpes
diagnosis
- presence of characteristic lesions
- IMMUNOASSAY reveals presence of viral antigen
Herpes
treatment + prevention
chemotherapeutic drugs help control the disease but do not cure it
-ACYCLOVIR
Chickenpox + Shingles
signs + symptoms
[chickenp]characterized by lesions on back + trunk that spreads across the body
[shingles]lesions localized to skin along w infected nerve
Chickenpox + Shingles
pathogen
VARIVELLA-ZOSTER VIRUS [VZV] causes both
Chickenpox + Shingles
pathogenesis
- infected dermal cells cause rash characteristics of chickenpox
- virus becomes latent in nerve ganglia
- –reactivation causes shingles
Chickenpox + Shingles
epidemiology
[chknpx]mostly infants/young kids. more severe in adults
[shingles]risk increases w age
Chickenpox + Shingles
diagnosis
based on characteristic lesions
Chickenpox + Shingles
treatment + prevention
- vaccines available against both
- treatment is for relief of symptoms
Warts
- benign epithelial growth on skin or mucous membranes
- Papillomaviruses cause warts
- most are harmless
- transmitted via direct contact + formites
Papillomavirus
- may cause warts
- some are ONCOGENIC due to ability to integrate into host cell DNA
Rubella (german measles)
- mostly infants/young kids; only humans
- children develop mild rash
- cased by rubella virus
- spread via respiratory secretions
- diagnosis: rash or serological testing
congenital infection of rubella can result in…
- teratogenic birth defects; or
- death of fetus
rubella vaccine is aimed for…
preventing rubella in pregnant women
Measles [Rubeola]
signs + symptoms
KOPLIK’S SPOTS
Measles [Rubeola]
pathogen + virulence factors
- caused by measles virus
- adhesion + fusion proteins help virus avoid immune recognition
Measles [Rubeola]
pathogenesis
-immune response to infected cells causes most symptoms
Measles [Rubeola]
epidemiology
- occurs mostly in infants/young kids; humans only
- measles is highly contagious
- spread via respiratory droplets
Measles [Rubeola]
diagnosis
based on signs of measles
Measles [Rubeola]
treatment + prevention
- no treatments
- MMR vaccine has measles immunization
- very rare due to vaccination
Mycoses
- caused by fungi
- most are OPPORTUNISTIC pathogens
- mycoses is classified by infection locations
Mycoses Class by infection locations
1 SUPERFICIAL
2 SUBCUTANEOUS
3 SYSTEMIC
Superficial Mycoses
signs + symptoms
- RINGWORM, dermatophytes (fungal agent) growing in upper dead tissue layers of skin
- NOT a parasitic worm
- white or black PIEDRA
- Pityriasis versicolor
Piedra
irregular nodules on hair shaft
-white piedra is dandruff
Pityriasis versicolor
hypo or hyperpigmented patches of scaly skin
Superficial Mycoses
pathogens
Piedraia hortae[cause black piedra]
Trichosporon beigelii[cause white piedra]
Malassezia furfur[cause pityriasis]
Superficial Mycoses
pathogenesis + epidemiology
- superficial fungi produce KERATINASE
- fungi transmitted via shared hair brushes/combs
Superficial Mycoses
diagnosis + treatment
piedra: diagnosed by appears; treated by shaving hair
pityriasis: ID by green color under UV light; treated w topical or oral drugs
