Bacteria Flashcards
Characteristics: gram stain, species, common infections, treatment
G+ cocci that inhabits intestinal tract
2 Species: Faecalis/Faecium
Grows in mediums up to 6.5% sodium chloride
Generally causes nosocomial infections that are resistant to most known antibiotics including vancomycin
Generally treat with Linezolid or Tigecycline
Name Pathogen
Enterococcus
Name pathogens represented and common features
Strep Pneumoniae and Strep Viridans
Both are Alpha-hemolytic
S. Agalactiae Illnesses
Known for serious infections of the newborn such as meningitis, sepsis, and pneumonia
All pregnant women are cultured at 35 weeks for presence of Group B strep infection and treated with intrapartum penicillin if positive.
Name the pathogen, describe characteristics including gram stain, specific tests, +/- capsule, hemolysis and other features
G+ positive cocci, + hippurate test, polysaccharide capsule, +CAMP Test, Beta-hemolytic, Bacitracin resistant
G+ cocci, catalase +, urease +, coagulase -, novobiocin sensitive
Staphylococcus Epidermidis
Common pathogen that infects artificial joints, implanted hardware (e.g. artificial heart valves), indwelling catheters
S. Epidermidis
Treatment
Due to resistance to many abx, requires Vancomycin
S. Pneumoniae
Pneumonia
Affects lower lobes, typically presents with rust colored sputum
Primary cause of CAP
S. Pneumoniae
IgA Protease
Cleaves IgA which allows it to colonize and invade mucosal tissues
S. Pneumoniae
Treatment
Susceptible to Erythromycin or Ceftriaxone
Also preventable with pneumonvax vaccines which bind polysaccharide capsule to a protein
S. Pneumoniae
Population most at risk of infection
Any individual who has had a splenectomy
Particularly high risk for sickle cell patients due to auto-splenectomy
S. Pneumoniae
General Characteristics and Virulence Factors
G+ lancet shaped diplococci that are optochin sensitive and bile soluble
Virulence: IgA Protease
S. Pyogenes
M Protein
Interferes with opsonization
Very antigenic and can cause molecular mimicry
S. Pyogenes
Streptolysin O
Lyses RBCs
Generates ASO antibodies
Diseases caused by Streptococcal Pyrogenic Exotoxin
Scarlet Fever
Toxic Shock Like Syndrome
Necrotizing Fasciitis
Rheumatic Fever Symptoms and Cause
Symptoms: after pharyngitis infection clears patient develops endocarditis, patient experiences type II hypersensitivity reaction:
J: Joint pain (polyarthritis)
O: myocarditis and pericarditis
N: Nodules
E: Erythema marginatum
S: Sydenham’s chorea
Generally causes mitral valve stenosis in later years.
Caused by molecular mimicry to M protein found in cell wall of S. Pyogenes
Post-streptococcal Glomerulonephritis
Type III Hypersensitivity Reaction
Circulating Ab-Ag complexes deposit in glomerulus
Sx: Cola-colored urine and facial swelling that occur 2 weeks after pharyngitis, impetigo, cellulitis, or erysipela infection
Can still occur despite antibiotic treatment of S. pyogenes infection
S. Pyogenes
Scarlet Fever Symptoms
Reddening or swelling of the tongue (strawberry tongue)
Pharyngitis - red, erythematous inflamed throat
Widespread rash that excludes the face
G+, catalase+, Urease+, Coagulase -, novobiocin resistant
Staphylococcus Saprophyticus
Common cause of UTIs in sexually active women
Staphylococcus Saprophyticus
S. Viridans
Endocarditis Pathogenesis
Occurs in damaged heart valves only
Generally patient has teeth cleaned leading to a transient bacteremia
Adheres to fibrin platelet aggregates on damaged heart valves by synthesizing dextrans from glucose
S. Viridans
General Characteristics
G+ cocci, alpha-hemolytic, unencapsulated, optochin resistant, bile insoluble
What two Staphylococcus bacteria are coagulase -?
What bacteria are in this image?
Staphylococcus Epidermidis and Saprophyticus
S. Aureus
What is TSST?
A super toxin found in S. aureus that has nonspecific binding to MHC class II positive T Cell receptors
Leads to a cytokine storm
What bacteria is this and describe general characteristics of this bacteria.
Staphylococcus aureus
G+ cocci in clusters, catalase +, coagulase +, beta-hemolytic
Grows on Mannitol Salt Agar and Blood Agar: Yellow colonies
Main Virulence Factor: Protein A
Toxins: TSST, exfoliative toxin
S. Aureus
What type of pneumonia occurs most commonly in what patient?
Patchy infiltrative pneumonia
Typically occurs as a superinfection post-viral LRI.
S. Aureus
Treatment
If Methicillin Sensitive - Nafcillin
MRSA - Vancomycin
S. Aureus
Endocarditis affects which valve and what patient population does it most commonly occur in?
Tricuspid valve - right sided
Typically found in IV Drug Users
S. Aureus
Symptoms and history of food poisoning related to this bacteria?
Typically causes vomiting without diarrhea
General history includes meat or cream based foods
S. Aureus
What is protein A?
Virulence factor that binds to Fc region of immunoglobulins preventing complement from binding and opsonizing/phagocytosing S. Aureus
S. Aureus
What is exfoliative toxin and what disease is it known for?
A protease toxin found in S. aureus. Primary cause of Staph Scalded Skin Syndrome.
S. Aureus
Toxic Shock Syndrome
Caused by leaving a foreign object in the body too long, such as a tampon or gauze after a rhinoplasty.
Mediated by TSST toxin
Name the pathogen and general characteristics including gram stain, shape, (un)encapsulated, hemolysis, and virulence factors
Streptococcus Pyogenes
G+ cocci in chains, encaspulated with hyaluronic acid
Beta-hemolytic
Virulence Factors: Streptolysin O, Streptokinase, DNAses, M protein, Streptococcal Pyrogenic Exotoxin
