Intro, Staph, and Strep Flashcards
Specificity
The Percentage of people correctly diagnosed as negative for a disease;
High specificity= Low false positives
Sensitivity
Percentage of people correctly diagnosed as positive for a disease;
High Sensitivity= Low false negatives
Routes of Transmission
Congenital Transfer (Mom to Fetus or Newborn)
Direct Contact (skin-to-skin contact)
Fomites (Inanimate objects)
Food and Water
Airborne (Aerosol)
Animals
Virulence Factor
A bacterial product that contributes to virulence or pathogenicity for the microorganism
Virulence (Pathogenicity)
The ability of a microorganism to cause infection and disease
Asymptomatic Infection (Carriage)
An infection by a disease-causing microorganism that causes no discernable symptoms in the host
Nosocomial Infection
An infection acquired in a hospital
Zoonoses
A disease transferred from an animal to humans
Colonization
Long-term persistence of a microorganism at a particular body site that does not lead to disease (e.t. Normal gut flora)
Disease
An infection that produces symptoms in the host
Infection
What a bacterium that causes disease becomes established in the host
Predictive Value
The positive predictive value is a way of measuring how accurate a specific test is
Sensitivity= (TP/TP+FN)) x100
Specificity= (TN/(TN+FP)) x100
Positive Predictive Value=
(TP/TP+FP) X100
Negative Predictive Value= (TN/(TN+FN) X100
Direct Agglutination
Blood test that looks for antibodies in a patient’s serum using whole organisms
Indirect (Passive) Agglutination)
Soluble antigens are bound to an insoluble particle such as latex to make the reaction visible
Reverse Passive Agglutination
Particle agglutination test in which the antibody is coated on a carrier molecule that detects antigen in the patient’s serum
Coagglutination
The technique used to detect specific antigens by utilizing the binding properties of protein A on S. aureus
Direct Immunofluorescence
A Test used to detect abnormal protein deposits by using fluorescent-tagged antibodies
Indirect Immunofluorescence
A Technique using a primary and fluorescent-tagged secondary antibody to detect antigens in cells or tissue (detects autoantibodies)
Staphylococcus
appears opaque, smooth, circular, convex colonies with butyrous consistency
Gram Positive cocci
Irregular Clusters
Catalase (+)
Ferments Glucose (no gas)
Facultative anaerobes
High NaCl tolerance
Selective media for Staphylococcus
Sheeps Blood Agar (SBA)
Mannitol salt agar (MSA)
Phenylethyl alcohol agar (PEA)
Columbia nalidixic acid agar (CNA)
S. aureus
Off-white to yellow, medium to large, Beta-hemolytic on SBA
Coagulase Positive
Pigment (+)
Mannitol (+)
Phosphatase (+)
Novobiocin Sensitive (-)
S. epidermidis
Pale, gray-white, medium, nonhemolytic on SBA
Coagulase Negative
Phosphatase (+)
S. saprophyticus
White (sometimes yellow), large, nonhemolytic on SBA
Coagulase Negative
Mannitol (+)
Novobiocin Resistant
S. aureus Diseases
Can infect nearly every organ and tissue in the human body:
Folliculitis
Furnucle
Boil
Cellulitis
Impetigo
Scolded Skin Syndrome
Toxic Shock Syndrome
Pneumonia
Osteomyelitis
Endocarditis
UTI
Arthritis
Blood
Food Poisoning
Enteritis
Wound Infection
S. epidermidis Diseases
Nosocomial bloodstream
Endocarditis
S. saprophyticus Diseases
UTIs (2nd most frequent in women)
S. haemolyticus Diseases
Endocarditis
Bloodstream
Peritonitis
UTIs
Irregular Staphylococcus species, Coagulase Negative
S. lugdunensis Diseases
Bloodstream
Endocarditis
Osteitis
Soft tissue infections
Uncommon Staphylococcus Coagulase Negative
S. aureus Virulence Factors- Capsule
Sugar capsule prevents phagocytic ability by immune system
S. aureus Virulence Factors- Toxins
Hemolysis (Alpha, Beta, Gamma, Delta)
Panton-Valentine Leukocidin- Kills WBCs
Exfoliative (epidermolytic) Toxin- Causes skin sloughing
Enterotoxins (food poisoning)
Pyrogenic Toxins (enterotoxins; stimulates hypersensitivity to toxin)
Toxic Shock Syndrome Toxin (TSST-1)
S. aureus Virulence Factors- Enzymes
Coagulase
Proteases
Lipases
Hyaluronidase- allows spreading of toxin through tissue cells
Staphylokinase- Helps Staph establish infection
S. aureus Virulence Factors- Adherhance Mechanisms
Fibronectin-binding protein-bridge between pathogen and host
Fibrinogen-binding protein- attaches to epithelial cells
Biofilm Formation- extracellular glycoconjugate
Protein A- bind to IgG Fc block
Toxic Shock Syndrome
localized infection
Symptoms: Fever, erythematous rash, skin shedding (soles and palms), hypotension (low blood pressure)
TSST-1 (pyrogenic toxin C)
Triggers production of proinflammatory cytokines acting as a superantigen (Stimulates T cells)
Damage from toxin and cytokine-stimulated host response
Methicillin-resistant S. aureus (MRSA) Antimicrobial Therapies
Clindamycin, doxycycline, rifampin, vancomycin, linezolid, daptomycin, tigecycline
Methicillin-sensitive S. aureus (MSSA) Antimicrobial Therapies
Clindamycin, quinolones, dicloxacillin, cephalosporins, SXT, macrolides
Coagulase Negative Staphylococcus (CNS) Antimicrobial Therapies
Quinolones, Augmentin, imipenem, vancomycin, cephalosporins
Vancomycin-resistant S. aureus (VRSA) Antimicrobial Therapies
Linezolid, daptomycin, tigecycline
Antibiotic
A metabolic byproduct of a microbe that inhibits growth or destroys microorganisms
Chemotherapeutic Agent
Chemically synthesized product that kills or inhibits the growth of a microbe
Bacteriostatic
An agent that prevents the growth of bacteria
Bacteriocidal
An agent that kills bacteria
Sulfa Drugs (Sulfonamides/Trimethoprim)
Synthetic agent to treat bacterial disease.
Inhibits folic acid production (nutrient needed by bacteria to grow)
Beta-lactams
Bactericidal- inhibits peptidoglycan biosynthesis
Penicillins
Cephalosporins
Monobactems
Carbapenems
Glycopeptides
Bactericidal- inhibits peptidoglycan biosynthesis
Vancomycin
Teicoplanin
Polymyxins
Bactericidal- targets gram (-), destabilizes phospholipids and LPS on outer membrane, Affect cell membrane permiability
Polymyxin B
Colistin
Macrolides
Bacteriostatic- inhibit bacterial protein synthesis
Erythromycin
Clarithromycin, Azithromycin
Tetracyclines
Bacteriostatic- Inhibit bacterial protein synthesis
Tetracycline
Doxycycline
Chloramphenicol
Bacteriostatic- Inhibit bacterial protein synthesis
Lincosamides
Bacteriostatic- Inhibit bacterial protein synthesis
Clindamycin
Streptogramins
Bacteriostatic- Inhibit bacterial protein synthesis
Quinupristin/Dalfopristin
Aminoglycosides
Bactericidal- interfere with protein synthesis (gram (-) bacteria)
Streptomycin
gentamicin
tobramycin
amikacin
kanamycin
Oxazonlidinones
Bacteriostatic- Inhibits bacterial protein synthesis
Linezolid
Glycylcycline
Bacteriostatic- Inhibits bacterial protein synthesis
Tigecycline
Metronidazole
Bactericidal- Disrupts DNA by generating cytotoxic intermediates
Fluoroquinolones
Bactericidal- Inhibits DNA gyrase
Lipopeptide
Bactericidal
Daptomycin
Nitrofurantoin
Bactericidal
Ansamycins
Bactericidal- inhibits transcription through RNA polymerase
Rifampin/Rifampicin
Isoniazid
Bactericidal- Treats TB by affecting the production of mycolic acid (makes up cell wall)
Ethambutol
Bacteriostatic- Affects arabinogalactan synthesis (integral part of cell wall structure)
Microbial Resistance
1) decrease the permeability of cell
2) alter the target site
3) enzyme inactivation
4) active transport out of the cell (efflux pump)
