Term
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Definition
• Stain purple when gram-stained
• Can be categorized into 2 major groups based on their DNA |
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Term
| Staphylococcus, Streptococcus, and Enterococcus |
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Definition
– Low G + C organisms
• Genera of cocci-shaped organisms |
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Term
| Bacillus, Clostridium, and Listeria |
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Definition
| • Genera of bacilli-shaped organisms |
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Term
| • Genera of bacilli-shaped organisms- |
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Definition
| Corynebacterium, Mycobacterium, Propionibacterium, Nocardia, and Actinomyces |
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Term
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Definition
• Normal members of every human’s microbiota
• Can be opportunistic pathogens |
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Term
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Definition
is most common organism on the surface of the skin
– Coagulase negative, usually mannitol negative; mostly opportunistic infections |
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Term
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Definition
is carried in 30-50% of healthy population (nose & perineum)
– Coagulase positive, by definition of species, usually mannitol positive; more virulent |
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Term
Staphylococcus aureus
Pathogenicity |
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Definition
Staph’ infections result when staphylococci breach the body’s physical barriers
• Entry of only a few hundred bacteria can result in disease
• Pathogenicity results from 3 features
– Structures that enable it to evade phagocytosis
– Production of enzymes
– Production of toxins |
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Term
| Structural Defenses Against Phagocytosis |
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Definition
• Protein A coats the cell surface
– Interferes with humoral immune responses by binding to IgG antibodies by Fc end
– Inhibits the complement cascade
• Bound coagulase
– Converts the soluble blood protein fibrinogen into insoluble fibrin molecules that form blood clots
– Fibrin clots hide the bacteria from phagocytic cells |
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Term
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Definition
• Cell-free coagulase
– Triggers blood clotting
• Hyaluronidase
– Breaks down hyaluronic acid, enabling the bacteria to spread between cells
• Staphylokinase
– Dissolves fibrin threads in blood clots, allowing S.aureus to free itself from clots |
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Term
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Definition
• Lipases
– Digest lipids, allowing staphylococci to grow on the skin’s surface and in cutaneous oil glands
• -lactamase
– Breaks down penicillin
– Allows the bacteria to survive treatment with -lactam antimicrobial drugs |
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Term
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Definition
• Staphylococcus aureus produces toxins more frequently than S.epidermidis
• Cytolytic toxins
– Disrupts the cytoplasmic membrane of a variety of cells
– Leukocidin can lyse leukocytes specifically
• Exfoliative toxins
– Causes the patient’s skin cells to separate from each other and slough off the body |
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Term
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Definition
• Toxic-shock-syndrome toxin
– Causes toxic shock syndrome
• Enterotoxins
– Stimulate the intestinal muscle contractions, nausea, and intense vomiting associated with staphylococcal food poisoning |
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Term
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Definition
• 3 categories
– Noninvasive Disease
• Food poisoning from the ingestion of enterotoxin-contaminated food
– Cutaneous Disease
• Various skin conditions including scalded skin syndrome, impetigo, folliculitis, and furuncles |
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Term
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Definition
– S. aureus is the number 1 cause in the U. S.
– Enterotoxin-producing strains contaminate food from the processor. If the food is not refrigerated, the organisms grow and produce the toxin that is ingested. Disease results.
– Symptoms include extreme nausea and vomiting, 2-4 hours after eating. Diarrhea may be present. |
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Term
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Definition
| – During broad-spectrum antibiotic treatment, resistant S. aureus may overgrow in the bowel. If they produces enterotoxin B, damage to intestinal mucosa results in cramps, pain, diarrhea, & fever |
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Term
Impetigo
Structure of a Boil: |
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Definition
| Furuncle on hand Carbuncle on neck |
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Term
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Definition
– Systemic Disease
• Toxic shock syndrome-TSS toxin is absorbed into the blood and causes shock
• Bacteremia-presence of bacteria in the blood
• Endocarditis-occurs when bacteria attack the lining of the heart
• Pneumonia-inflammation of the lungs in which the alveoli and bronchioles become filled with fluid
• Osteomyelitis-inflammation of the bone marrow and the surrounding bone |
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Term
| Toxic Shock Syndrome, U.S. ‘79-’94 |
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Definition
Staphylococcal TSST
functions as a “Super antigen”;
activating large numbers of
T cells nonspecifically. This
results in symptoms caused
by a toxic overdose of certain
immune cytokines, like IL-2.
Symptoms: high fever, rash,
vomiting, diarrhea, and renal,
liver, and blood involvement. |
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Term
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Definition
activating large numbers of
T cells nonspecifically |
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Term
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Definition
| the drug of choice to treat staphylococcal infections |
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Term
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Definition
– Proper food preparation and storage practices
– Hand antisepsis is the most important measure in preventing nosocomial infections
– Also important is the proper cleansing of wounds and surgical openings, aseptic use of catheters or indwelling needles, an appropriate use of antiseptics |
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