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Flashcards in Bacteria- Gram Positives Deck (28):

What are the characteristics of Staph aureus

Gram positive, bundle of grapes, golden appearance, catalase positive, coagulase positive, beta hemolytic, ferments mannitol salt agar, colonizes the nose, and Protein A prevents opsonization


What are the inflammatory infections of Staph aureus

Post-viral pneumonia, septic arthritis, osteomyelitis, and acute tricuspid endocarditis


What are the toxic infections of Staph aureus

Scalding skin syndrome- skin falls off due to toxin protease
TSS- TSST (superAg) causes non specific binding of MCHII and TRC causing cytokine storm (tampon in for too long)
Food poisoning- rapid onset with more vomit than diarrhea


Explain MRSA; why is it resistant and how do you treat

Methylcilline resistant staph aureus

Resistant to methylcillin by binding PGP (penicillin binding protein)

Treat with vancomycin


How do you treat Staph aureus normally



Staph epidermidis

Gram positive, catalase positive, urease positive, normal flora of skin, forms biofilms, novobiocin sensitive, enemy of ortho surgeons because it infects prosthetics, causes endocarditis of artificial heart valves, treat with vancomycin


Staph saprophyticus

Gram positive, catalase positive, urease positive, novobiocin resistant, causes UTI in sexually active females


Group A Strep pyogenes- characteristics, virulence factors, and treatment

Gram positive, beta hemolytic, HA capsule

Virulence factors- Streptolycin O (beta hemolysis), streptokinase (activate plasmin), and DNase

Group A strep is bacitracin sensitive


Group A Strep- infections, exotoxin infections

Impetigo (honey crusted skin), pharyngitis, and erysipelas cellulitis
Scarlet fever- strawberry swollen tongue, pharyngitis, and rash sparing the face (Spe A and C)
Necrotizing fasciitis- Spe B


Group A Strep- post strep infections

Rheumatic fever- M protein (molecular mimicry of myosin causing mitral valve stenosis), JONES (joint polyarthritis, heart murmur and myocarditis, nodules of knee of elbows, erythema marginatum, syndenham chorea (jerking hands and face)

Post strep glomerulonephritis- brown cola colored urine and facial edema treat with penicillin


Group B Strep agalactiae

Gram positive, polysaccharide capsule, hipporate positive, CAMP arrowhead positive, beta hemolytic, bacitracin resistant

Transmitted via vaginal delivery

Neonatal meningitis, sepsis, and pneumonia


Strep pneumoniae

Gram positive, diplococci, encapsulated, alpha hemolysis, bile soluble/sensitive, optochin sensitive, and IgA protease

Rusty bacterial MOPS- bacterial meningitis, otitis media, lower lobar pneumonia with rusty color sputum, and sinusitis

Treat with macrolides and ceftriaxone

Vaccine- adulti (T independent IgM) and childhood (IgG)


Strep viridians

Gram positive, alpha hemolysis, bile insoluble/resistant, optochin resistant

Dental caries (s mutans)
Subacute mitral endocarditis by binding platelets via dextrans


Enterococcus faecalis and faecium

Gram positive and grow on 6.5% NaCl
E. Faecium- superbug, bile insoluble, vancomycin resistant
Cause UTI, biliary tree infections, and endocarditis


Bacillus anthracis- characteristics and toxins

Gram positive, obligate aerobe, spore forming, polyD glutamate capsule

Lethal factor- cleaves MAPK- black eschar necrosis
Edema factor- inc cAMP- causes edema


Bacillus anthracis- infections and treatment

Pulmonary anthrax/wool sorters disease- dry cough, pulmonary hemorrhage, and hemorrhagic mediastinitis (widened mediastinum on X ray)

Treat with flouroquinolones and tetracycline


Bacillus cereus

Fried rice syndrome- vomit and diarrhea


Clostridium tetani- characteristics and toxin

Gram positive, obligate anaerobe, spore forming

Rusty metal wound allows spore to enter, germinates and releases toxin, travels retrograde up motor neuron to spinal cord, cleaves snare protein, prevents release of GABA and glycine from renshaw cells


Clostrium tetani- infection and vaccine

Spastic paralysis
Risus sardonicus

Vaccine- toxoid


Clostridium botulinum- characteristics and toxin

Gram positive, obligate anaerobe, spore forming

Botulinum toxin cleaves snare proteins preventing the release of Ach from motor neurons affecting the PNS


Clostridium botulinum- infection

Botulism- flaccid descending paralysis

Childhood botulism- infant ingests spore in honey which germinates in anaerobic infant gut causing floppy baby syndrome

Adult botulism- ingest preformed toxin from contaminated canned food


Clostridium difficile- characteristics and toxins

Gram positive, anaerobic, spore forming, nosocomial

Exotoxin A- binds brush border enzymes -> watery diarrhea
Exotoxin B- depolymerizes actin -> enterocyte death -> pseudomembranous colitis (greyish yellow exudate lining colonic mucosa)


Clostridium difficile- diagnosis and treatment

Presence of pseudomembranes in colon, PCR detects toxin in stool sample

Treat via oral vancomycin and metronadizole


Cornybacterium diptheriae- general and exotoxin

Gram positive, rod shaped like a Y or V, metachromatin granules, transmitted via resp droplets

Exotoxin subunit A (active) and subunit B (binding) inhibits translation via ribosylation of elongating factor 2


Cornybacterium diptheriae- infections and diagnosis

Greyish yellow pseudomembrane in oropharynx leads to LAD and thick bull neck

Arrhythmia, myocarditis, and heart block

Damage myeline of nerve fibers leading to pharyngeal paralysis

Culture pseudomembrane on tellurite agar and loefflers medium and positive eleks test


Listeria monocytogenes- general and motility

Gram positive, motile, bacillus, catalase positive, narrow zone of beta hemolysis, survives low temp (found in milk and soft tissue)

EC tumbling motility via flagella
IC actin rocket propulsion


Listeria monocytogenes- infection and treatment

Meningitis in newborns and adults over 60

Treat with ampicillin


Actinomyces israelii- general, infection, and treatment

Gram positive, anaerobe, branching filamentous rod, normal flora of oral cavity

Infect due to jaw trauma or dental work
Cervicofacial actinomyces- nontender lump on jaw and sinus draining yellow pus with sulfur granules

Treat with penicillin