Term
General Features of Staphylococcus
- Distinctive Enzymes
- Growth characteristics
- Distribution
- Pathogenic species |
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Definition
Distinctive Enzymes:
- Catalase
Growth characteristics:
- grape-like morphology
- wide temp range (18-42°C)
- halophilic
Distribution:
- world-wide
- everyone colonized- skin, mucous membranes, nares
- transmisson is person-person, direct contact, clothing
Pathogenic Species:
- S. aureus
- S. epidermis
- S. saprophyticus
- other coagulase (-) staphylococci |
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Term
Staphylococcus aureus
- ID
- respiration
- hemolysis
- exclusive features |
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Definition
ID:
- catalase (+)
- coagulase (+)
- novobiocin resistant (diff. from S. epidermidis)
- ferments mannitol (diff. from other Staphylococci)
Hemolysis: β or γ
Capsule: yes
Respiration:
- aerobic
- facultative anaerobe via fermintation of pyruvate (or derivative) to lactate
Other:
- detect catalase via rabbit plasma coagulation
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Term
Staphylococcus aureus
- surface structures → virulence factors
- diseases |
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Definition
Surface structures & virulence factors:
- capsule (VF)
- peptidoglycan (VF) ~activates complement, stimulates inflammatory cytokines
- Techoic acid~ protective, control enzyme activity, binding receptors and surfaces
- surface protein adhesins
- Protein A~ *virulence factor*, binds Fc portion of Abs → ↓opsonization & clearance; Abs against it non-protective
- β-lactamase, leukocidins, enterotoxins, exfoliative toxins (A & B), Toxic shock syndrome toxin 1 (TSST-1) superantigen → binds MHC class 2 then stimulates T-cell to produce massive amount of IL-2 leading to widespread inflammation
Diseases:
- furuncle/carbuncle
- impetigo
- bacteremia and endocarditis
- bone and joint infectiosn
- wound infections
- pneumonia
- toxic shock syndrome
- staphylococcal scalded skin syndrome (SSSS) aka "Ritter's disease"; toxin attacking desmosomes |
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Term
Staphylococcus epidermidis
- infection routes
- special structure |
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Definition
Infection routes:
- prosthetic device infection (heart valves, knee joints etc)
- long IV durations
Special Structure:
- capsular polysaccharide adhesin |
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Term
Staphylococcus saprophyticus
- disease |
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Definition
Disease:
- cause of urinary tract infection in young women |
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Term
Streptococcaceae
- significant human pathogens
- general characteristics
- growth
- hemolysis
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Definition
Significant human pathogens:
- Streptococcus pyogenes (group A)
- Streptococcus agalactiae (group B)
- Streptococcus pneumoniae (Pneumococcus)
- virdians streptococci
- mutans streptococci
General characteristics:
- non-motile
- non-spore forming
- divide end-to-end (length depends on medium)
- catalase (-)
Growth:
- facultative anaerobes
- use variety of CHOs needing complex nutrition
- CO2 enhances growth
- ferment glucose to lactose and no further and makes no gas (homofermentive)
Hemolysis: all |
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Term
Streptococcus pyogenes
- Group
- hemolysis
- culture requirements for identification
- surface components and virulence
- extracellular enzymes of note
- diseases
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Definition
Group and Hemolysis:
- Group A, β-hemolytic
Culture requirements for identification:
- blood agar with 5% CO2
- bacitracin "A" disk (for ID)
Surface components:
- M-protein (major virulence factor)
- F-protein
- capsule
- lipotechoic acid
Extracellular enzymes:
- C5a peptidase
- streptokinase (includes Streptolysin O & S)
- spreading factors
Diseases:
- localized suppurative diseases
~ pharyngitis, tonsilitis, cellulitis, necrotizing fasciitis, puerperal sepsis, erysipelas
- toxin mediated diseases
~ scarlet fever, streptococcal TSS
- autoimmune disease
~ rheumatic fever, glomerulonephritis |
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Term
M-protein
-function
-disease
-organism |
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Definition
Function:
- inhibits phagocytosis and intracellular killing via opsonization inhibition
- synergistic with lipotechoic acid in binding to epithelial cells
Disease:
- rheumatic fever (serotypes 1,3,5)
- Abs are protective
Organism:
- S. pyogenes |
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Term
Strep pyrogenic exotoxins (SPE A & B)
- disease(s) |
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Definition
Diseases:
- scarlet fever
- involved in streptococcal toxic shock syndrome
*Superantigen and carried by bacteriophages |
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Term
Streptococcus agalactiae
- group
- hemolysis
- lab findings (ID)
- disease |
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Definition
Group and hemolysis:
- Group B and weakly β- or γ-hemolytic
Lab Findings for ID:
- CAMP test~ synergistic β-hemolysis with S. aureus
Diseases:
- puerperal sepsis (childbed fever)
~ post-partum endometritis/bacteremia/bacteriuria
- newborn infections
~ bacteremia, meningitis, pneumonia
- late-onset neonatal disease
~ 1-3 months post-partum bacteremia or meningitis
- infection in compromised host
~ diabetes, cirrhosis, renal disease, HIV
**66% not associated with pregnancy or immunocompromise** |
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Term
Viridans streptococci
- Group
- hemolysis
- ID
- examples |
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Definition
Group and Hemolysis:
- non-typable via Lancefield; α-hemolytic
ID:
- Optochin (P-disk) resistant
- catalase (-)
Examples:
- S. salivarius
- S. mitis
- mutans streptococci
- S. sanguis |
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Term
Mutans streptococci
- disease and process |
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Definition
Disease:
- dental caries
Process:
- has surface adhesins for enamel thus promoting plaque
- converts sucrose to acetic & lactic acid → tooth erosion |
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Term
Streptococcus pneumoniae
- growth and ID
- hemolysis
- surface structures
- enzymes
- diseases |
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Definition
Growth, hemolysis, and ID:
- blood agar; α-hemolysis
- ethylhydrocuprine hydrochloride (optochin) on filter paper disk inhibits growth of pneumococci
- bile soluble = activates autolysins of pneumococci → death of pneumococci
- spread by humans only via water/air droplets
Surface structures:
- capsule~ quellung rxn in presence of abs; VIRULENCE FACTOR (serotype 3 esp.)
Enzymes:
- pneumolysin
- IgA protease
- hyaluronidase
- neuraminadase
Diseases:
- pneumococcal pneumonia (50-80% of bacterial pneumonia)
- otitis media
- sinusitis
- endocarditis
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Term
Enterococcus
- group
- species of interest
- growth, hemolysis, ID
- surface components
- enzymes
- infections |
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Definition
Group:
- formerly Lancefield Group D streptococci
- GI, GU, biliary tract
Species:
- E. durans, E. faecium, E. Faecalis (80-90% of infections)
Growth, Hemolysis:
- α-, β-, or γ-hemolytic
- hydrolyzes esculin in presence of 40% bile
- growth in 6.5% NaCl
Surface components:
- lipotechoic acid→ TNF-α and interferon
- extracellular surface protein~ avoid Abs
- aggregation substance
Enzymes:
- cytolysin (toxin)
- bacteriocin (broad spectrum)
- gelatinase (biofilm and cleaves C3)
- hyaluronidase
Infections:
- UTIs
- bacteremia
- endocarditis
- intraabdominal infections
- wound infections
- neonatal sepsis
*not killed by cell wall antibiotics and highly antibiotic resistant |
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