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Streptococcus Flashcards (Mostly Repiratory)


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5 human pathogenic species of Strep.
Strep A (pyogenes), Strep B (agalactiae), Strep D (faecalis, fecium, bovis, equines), Strep pneumoniae
Stain for Strep
Gram positive
Strep morphology
Spherical cocci in Strips/Chains or paired (diplococci)
Strep that completely lyses RBCs
Are most beta-hemolytic Strep bacitracin resistant? Yes or No What is the exception?
Yes, S. pyogenes (bacitracin inhibits growth)
Result of Strep catalase test
Catalase negative
Strep that leaves a greenish discouration of the culture medium surrounding the colony; indicating only partial lysing of RBCs
Classification of bacerteria that is non-hemolytic
Antigens found on C carbohydrate of the cell wall
Lancefield antigens
Major virulence factor of S. pyogenes that inhibits the activation of complement and protects it from phagocytosis by aiding in adherence to epithelial cells
M protein
S. pyogenes virulence factor that binds fibronectin and is important for adherence
Protein F
S. pyogenes virulence factor that binds Fc portion of antibodies, which may lead to a covering of antibodies on the bacterial surface facing outward (the “wrong way”) interfering with host diction and completment activation
Protein G
Most common bacterial cause of pharyngitis
S. pyogenes
Superantigen causing TSS-like syndrome
Exotoxin A
Pore forming proteins that lyse host cells
Oxygen labile(sensitive) hemolysin
Streptolysin O
Oxygen stable hemolysin
Streptolysin S
Responsible for beta-hemolysis
Streptolysin O and Streptolysin S
Protein that is the basis for ASO titer testing for recent strep infection
Streptolysin O
Superantigens that can cause scarlet fever
Pyrogenic exotoxins
Lyses fibrin blood clots, can be used in treatment of myocardial infarctions
Degrades C5a
C5a peptidase
Hydrolyzes the ground substance of connective tissue
Depolymerizes DNA in necrotic tissue
S. pyogenes transmission
Direct mucosal contact, large droplets produced by coughing, sneezing, or conversation. (Asymptomatic carrier rate <5%)
S. pyogenes diagnosis
Gram + cocci pairs/chain, catalase (-), beta-hemolytic, culture: bacitracin sensitive
S. pyogenes treatment
T or F: There is a viable vaccine for S. pyogenes
Another name for Group A Streptococcus
S. pyogenes
T or F: On the basis of symptoms, pharyngitis caused by S. pyogenes can be distinguished from pharyngitis caused by other organisms
Caused by exotoxin A superantigen excreted by S. pyogenes. Clinical findings include shock, renal impairment, rash, repiratory failure, and diarrhea
Toxic Shock-like Syndrome
Rare group A streptococci infection of the endometrium at or near delivery
Puerperal infection
Drug that shuts down Strep metabolism and toxin production
Penicillin G
Characterized by strep throat with sandpaper rash; caused by pyrogenic exotoxin
Scarlet Fever
S. pyogenes skin infections
Impetigo (localized skin disease, generally in children), Erysipelas (skin and subcutaneous tissue), Wound/Burn infections, Scarlet Fever
Characterized by fever, carditis, subcutaneous nodules, migratory arthritis, rash, chorea.
Rheumatic Fever
Delayed antibody mediated diseases caused by S. pyogenes
Rheumatic Fever and Acute Glomerulonephritis
Can cause cardiac enlargement, valvular murmurs, effusions, and heart failure secondary to antibody mediated attack of the heart.
Rheumatic Fever
Follows untreated pharyngitis but not after skin infection or any other non-repiratory or non-Group A infections.
Rheumatic Fever
Autoimmune disease caused by antigenic similarities between streptococcal and human tissue antigens leading to cross reactivity
Rheumatic Fever
Patients can have recurrent episodes of ______ leading to progressive heart damage
Rheumatic Fever
History of this disease requires profilactic penicillin when undergoing predures known to cause transient bacteremia such as dental extraction.
Rheumatic Fever
Disease primarily associated with children, characterized by edema, hypertension, hematuria and proteinurea, and pathologically by diffuse proliferative lesions of the glomeruli.
Acute Glomerulonephritis
Disease mechanism includes deposition of antigen-antibody complexes on the .glomerular basement memberane with complement activation and consequent inflammation
Acute Glomerulonephritis
Disease may follow either skin or repiratory group A strep infections, and is only caused by nephritogenetic strains.
Acute Glomerulonephritis
Most common cause of community acquired bacterial pneumonia
S. pneumoniae
Gram (+), alpha-hemolytic streptococci, lancet-shaped cocci in pairs (diplococci)
S. pneumoniae
S. pneumoniae virulence factor that prevents phagocytosis and contains IgA proteases that cleave antibody
Polysacchride Capsule
Disease mechanism of this streptococcus involves no toxins and massive multiplication leading to inflammation
S. pneumoniae
S. pneumoniae transmission
Normal flora of oropharynx
S. pneumoniae diagnosis
Gram + diplococci, Quelling reaction (capsular swelling), alpha hemolytic, culture (does not grow with presence of bile or optochin)
S. pneumoniae treatment
Penicillin G, erythromyocin
Recommended vaccine for people over the age of 65
S. pneumoniae vaccine
Diseases associated with S. pneumoniae
Pneumonia and Meningitis in adults, Otitis Media in children, Sepsis, Bronchitis, and Sinusitis among other URTIs.
Main streptococci that cause URTIS
S. pyogenes, S. pneumoniae, S.agalactiae, Enterococcus faecalis, S.bovis, Viridans group strep
Of the 5 major human pathogenic streps, which 2 have no Lancefield antigen
Virdans Group Strep and S. pneumoniae
Babies acquire from mothers during delivery, causes neonatal meningitis, pneumonia and sepsis
Group B Strep (S. agalactiae)
Alpha-hemolytic group of strep that causes dental infections (S. mutans), subacute bacterial endocarditis, and absesses (S. inermedius)
Viridans Group Strep
Enterococcous faecalis, Enterococcous faecium, Streptococcous bovis, Streptococcus equinus
Group D Streptococci (alpha-hemolytic)
Associated with 50% of colon malignancies
S. bovis (Group D strep non-enterococcal)
Gram (+) bacteria that can cause pneumonia
S. pyogenes, S. pneumoniae, S. aureus, TWAR strain of C. pneumoniae
Gram (-) bacteria that can cause pneumonia
Haemophilus influenzae, Klebsiella (encapsulated), Enterobacter, Serratia, Proteus/Morganella/Provedencia, Pseudomonas (CF), and Legionella pneumophila
Characterized by acute onset, high fever, chills, productive cough, pleuritic chest pain, high WBCs, pulmonary infiltrates, and pulmonary consolidation on PE.
Acute Pneumonia
Causes of Acute Pneumonia (in order of importance)
S. pneumoniae, H. influenzae, K. pneumoniae, S. aureus, Anerobic bacteria, Myobacterium TB
Marked by gradual onset, low grade fever, non-productive cough, and normal WBCs
Chronic/Atypical Pneumonia
Causes of Chronic Pneumonia
Mycoplasma pneumoniae, Legionella pneumophila, Coxiella burnetti (Q fever), TWAR strain of C. pneumoniae, Chlamydia psittaci, Viral and Fungal
Hospital-acquired pneumonia
Klebsiella/Enterobacter/Serratia, E. coli, Pseudomonas aeruginosa, Acintobacter, Anaerobic bacteria
Common Lower Respiratory Pathogens in Neonates
E. coli, S. agalactiae
Common Lower Respiratory Pathogens in Infants
Chlamydia, RSV
Common Lower Respiratory Pathogens in Children
Common Lower Respiratory Pathogens in Teens/Young Adults
Mycoplasma, S. pneumoniae, B. pertussis
Common Lower Respiratory Pathogens in Adults
S. pneumoniae, Chlamydia, Mycoplasma, Viruses
Common Lower Respiratory Pathogens in the Elderly
E. coli, Klebsiella, S. aureus, Legionella, H. influenzae type B
Common Lower Respiratory Pathogens in HIV+/AIDS patients
S. pneumoniae, C. neofomans, Pneumocystis jiroveci (P. carinii)
Common Lower Respiratory Pathogens in Organ Transplant patients
Common Lower Respiratory Pathogens in patients on chemotherapeutic or immunosuppressant drugs
Aspergillus, other fungi

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