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two main phyla of gram-positive bacteria
firmicutes and acintobacteria
characteristics of Staphylococcus
catalase positive, salt tolerant (up to 10% NaCl)
two species commonly associated with staphylococcal disease
Staphylococcus aureus, Staphylococcus epidermidis
pathogenicity of Staphylococcus
defense: Protein A enzymes: coagulase, hyaluronidase, staphylokinase, lipase, penicillinase (beta-lactamase) toxins: cytolytic toxins, exfoliative toxins, TSS toxins, enterotoxin
protein A
a protein that coats S. aureus that interferes with the antibody immune responses by binding to the stems of IgG; inhibits opsonization
coagulase
triggers blood clotting
hyaluronidase
hydrolyzes hyaluronic acid, a major component of the matrix between cells
staphylokinase
dissolves fibrin threads in blood clots, allowing S. aureus to free itself from clots
lipase
digests lipids, allowing staphylococci to grow on the surface of the skin and in cutaneous oil glands
penicillinase (beta-lactamase)
breaks down penicillin to help, allowing bacteria to survive antimicrobial treatment
cytolytic toxins
work by degrading cytoplasmic membrane integrity, causing cell lysis and death
exfoliative toxins
cause skin cells to separate and slough off
TSS toxins
protein that causes TSS
enterotoxins
cause intestinal disturbance
three categories of staphylococcal diseases
noninvasive, cutaneous, systemic
noninvasive disease of Staphylococcus
food poisoning
three cutaneous diseases of Staphylococcus
scalded skin syndrome, impetigo, folliculitis
scalded skin syndrome
pyogenic lesions whereby epidermal layers peel off--does not contain staph cells, just the toxin
impetigo
staph infection (contains cells)
folliculitis
inflammation of the hair follicle
six systemic diseases of Staphylococcus
TSS, bacteremia, endocarditis, pneumonia, empyema, osteomyelitis
toxic shock syndrome (TSS)
potentially fatal condition characterized by fever, vomiting, red rash, low blood pressure, and loss of sheets of skin
bacteremia
presence of bacteria in the blood
endocarditis
inflammation stemming from bacterial invasion of the outer layers of the heart and heart valves
pneumonia
inflammation of the alveoli and bronchioles and the accumulation of fluid
empyema
accumulation of pus in the space between the lung and chest wall
osteomyelitis
inflammation of the bone marrow and bone tissue
characteristics of Streptococcus
catalase negative, cocci arranged in chains or pairs
specie differentiation of Streptococcus
hemolysis reactions and serological reactions (Lancefield antigens). group A streptococci (ex. Streptococcus pyogenes) have large zones of beta-hemolysis, group B streptococci (ex. Streptococcus agalactiae) have small zones of beta-hemolysis. viridans group have alpha-hemolysis
pathogenicity of group A Streptococcus
defense: M protein, hyaluronic acid capsule toxins: pyrogenic toxins, streptolysins
M protein
interferes with complement; prevents opsonization; allows strep to adhere to cells
hyaluronic acid capsule
protects/hides from phagocytosis
pyrogenic toxins
stimulate fever
streptolysins
lyse RBC, WBC, and platelets--interfering with the oxygen-carrying capacity of the blood, immunity, and blood clotting
diseases of group A Streptococcus
pharyngitis, scarlet fever, pyoderma and erysipelas, toxic-shock-like syndrome, rheumatic fever, glomerulonephritis, necrotizing fasciitis
pharyngitis
inflammation of the pharynx; "strep throat"
scarlet fever
rash and systemic toxemia following pharyngitis
pyoderma and erysipelas
pus-filled lesions on skin (pyoderma); localized swelling and inflammation (erysipelas)
toxic-shock-like syndrome
bacteremia and multi-system inflammation and failure
rheumatic fever
damage to heart valves following pharyngitis
glomerulonephritis
inflammation of the glomeruli and nephrons
necrotizing fasciitis
"flesh-eating" bacteria disease
pathogenicity of group B Streptococcus
capsules (not very effective); mainly infect newborns and now the elderly
diseases of group B Streptococcus
neonatal bacteremia, meningitis, pneumonia
meningitis
inflammation of the meninges
diseases of viridans streptococci
dental caries
dental caries
cavities
pathogenicity of Streptococcus pneumoniae
capsules, adhesins, pneumolysins
pneumolysins
bind cholesterol and make holes in host cells
diseases of Streptococcus pneumoniae
sinusitis, otitis media, bacteremia, endocarditis, pneumococcal meningitis
sinusitis
acute infection of the paranasal sinuses
otitis media
acute infection of the ear
characteristics of Enterococcus
catalase negative, Lancefield group D (but unencapsulated) and are not hemolytic
two types of Enterococcus
E. faecalis and E. faecium (both found in the human colon)
pathogenicity of Enterococcus
bacteriocins
bacteriocins
cytolysins that inhibit growth of Gram-positives
diseases of Enterococcus
10% of nosocomial infections, bacteremia, endocarditis and wound infections
characteristics of Bacillus
soil dwelling organisms that produce endospores, arranged single, in pairs, or in chains; most notable pathogenic species is Bacillus anthracis
pathogenicity of Bacillus
anthrax toxins
anthrax toxins
create holes in host cells; stimulate apoptosis
diseases of Bacillus
anthrax (GI anthrax, cutaneous anthrax, inhalation anthrax)
anthrax
can be fatal without aggressive treatment; caused by ingestion, inoculation, or inhalation of spores of Bacillus anthracis
characteristics of Clostridium
ubiquitous in the soil, water and GI tract of animals, produces endospores
four notable species of Clostridium
Clostridium perfringens (gas gangrene) Clostridium difficile (pseudomembranous colitis) Clostridium botulinum (botulism) Clostridium tetani (tetanus)
pathogenicity of Clostridium botulinum
produces 7 distinct botulism toxins, which are very deadly and prevent neurotransmitter release resulting in flaccid paralysis
pathogenicity of Clostridium tetani
produces tetanospasmin (tetanus toxin) that causes both muscles in an antagonistic pair to contract
characteristics of Listeria
low G + C, Gram-positive, non-endospore-forming, rod-shaped bacterium with end-over-end, tumbling motility outside the body. It is found in soil, water, and animals, including insects. It enters the body through consumption of contaminated drink or food, typically deli meats, hot dogs, soft cheeses, and yogurt
pathogenicity of Listeria monocytogenes
enters body through contaminated food/drink and causes listeriosis; rarely pathogenic in health adults, but can infect pregnant women, fetuses, newborns, the elderly, and immunocompromised people resulting in meningitis. Listeria is tolerant of cold temperatures, so it can
signs and symptoms of listeriosis
nonspecific flulike symptoms in healthy, nonpregnant adults. In contrast, infection in pregnant women, fetuses, newborns, the elderly, and immunocompromised patients can be severe, causing bacterial meningitis and possibly death
treatment of listeriosis
ampicillin and other antimicrobials
characteristics of Corynebacterium
high G + C, pleomorphic, non-endospore forming, snapping division; all species are pathogenic--Corynebacterium diptheriae
pathogenicity of C. diptheriae
lysogenic bacteriophage in cell that produces the diptheria toxin; cells lacking bacteriophage are non-pathogenic
diptheria toxin
blocks polypeptide synthesize; formation of pseudomembrane
characteristics of Mycobacterium
high G + C, non-endospore-forming pathogen; cell walls with waxlike mycolic acid; two notable disease in humans are M. tuberculosis and M. leprae (tuberculosis and leprosy)
tuberculosis
a respiratory disease caused by infection with M. tuberculosis; its disseminated form can result in wasting away of the body and death
leprosy
disease caused by infection with M. leprae that produces either a non-progressive tuberculoid form or a progressive lepromatous form that destroys tissue, including facial features, digits, and other structures
characteristics of Propionibacterium
non-endospore forming, found on skin, produce propionic acid as a byproduct of fermentation; causative agent of acne in 85% of adolescents and young adults
characteristics of Nocardia
common inhabitor of soils rich in organic matter; mycolic acid in cell wall; acid fast stain
characteristics of Actinomyces
hypha-like cells; causes actinomycosis
actinomycosis
characterized by formation of multiple, interconnected abscesses in skin or mucous membrane