Term
| What are the functional differences between Staph and Strep along with the differences between their subspecies? What are all the members? (See 239 mainly) |
|
Definition
-Hit the cat with the Staph (Staph are catalase+)
-Staph aureus is the only one with coagulase
-Hemolysis is more complicated
-Know the three antibiotic resistances |
|
|
Term
| What are alpha, beta, and gamma hemolysis? |
|
Definition
| -Beta is total, alpha some, gamma none |
|
|
Term
| What defines Staph epidermidis and saprophyticus in terms of distinguishing the two? |
|
Definition
-In both we're concerned about UTI's more than anything
-Epi is more with older women with catheters
-Sapro is more with young women who just started having sex (Think sapphic)
-Additionally, epi is sensitive to *novobiocin, and sapro is resistant
-Epi can also cause endocarditis; mostly in IVDUs, and in patients with prosthetic valves (likes plastic apparently) |
|
|
Term
| How do we test for staph aureus/identify it? |
|
Definition
-A coagulase test is very telling (only gram+ cocci with it)
-It makes **yellow colonies on *blood agar (and also clears the blood because of the beta-hemolysis)
-It also ferments *mannitol and is *salt tolerant (grows on *mannitol-salt agar) |
|
|
Term
| Where do we usually find Staph aureus? How is it transmitted? |
|
Definition
-In the boogies
-Then it gets on the fingies lol
-Can be from hand contact, sneezing, and often in foods (namely; custards, potato salad, and canned meats) |
|
|
Term
| What are the risk factors for S. aureus? |
|
Definition
-*Surgery/wounds (one of most common)
-TSS from leaving tampons in back in the day
-Also, *CGD because all Staph species are *catalase+ |
|
|
Term
| What does staph aureus have that makes it virulent? |
|
Definition
1. Major is **TSST
2. Also has enterotoxins (important in food poisoning... from the boogies haha)
3. Exfolatins; cause the scalded skin syndrome in babies
4. Protein A binds to Fc portion
5. Coagulase - causes it to be more localized |
|
|
Term
| What diseases do we see with S. aureus (9)? |
|
Definition
1. Gastroenteritis; 2-6 hours after eating the toxin (not bacteria, bc the enterotoxin is heat stable)
2. *Endocarditis (acute); usually from **IV drug use (most common cause in druggies; otherwise is second to **viridans Strep (subacute))
3. Abscesses, boils, mastitis (breasts), etc.
4. *TSS; fever, sunburn like rash, peeling palms and soles, hypotension, multiorgan failure, and death (from TSST-1)
5. Impetigo; patchy erythematous papules/bullae, can be Staph or Strep (catalase test needed), often school kids
6. Scalded skin syndrome; in infants from exfoliatins
7. Pneumonia; nosocomial from ventilators with high fatality rate, salmon color (less common cause of pne)
8. Surgery infection; **most common cause of
9. Osteomyelitis; bone infection, more in children, **most common cause of (unless they have sickle cell, then it's salmonella) |
|
|
Term
| How do we treat staph aureus infections? |
|
Definition
-We usually treat with **penicillin drugs such as nafcillin, oxacillin, *methacillin, etc. (all end in -cillin and are B-lactamase resistant)
-However, *MRSA is resistant even to these beta-lactams, so for it we prefer **vancomycin (binds D-ala, D-ala), which is even getting some resistance |
|
|
Term
| Shapewise, what is the diff. b/t staph and strep? |
|
Definition
-Staph are in clusters, strep is in chains (usually)
-Think strep = strip = chains
-Plus staph has coagulase, so it stays concentrated, as another memory tool |
|
|
Term
| What can help us distinguish Strep pyogenes from the other Strep members? |
|
Definition
-It is beta hemolytic (so is group B)
-It is bacitracin sensitive (group B is not)
-Also it is PYR positive (Enterococcus faecalis/faecium is the only other member that is) |
|
|
Term
| Where do we find it on the body and what is transmission? |
|
Definition
-Throat (it is strep after all)--->respiratory droplets
-Skin--->contact |
|
|
Term
| What are the virulence factors for S. pyogenes? |
|
Definition
1. Major is **M-protein; antiphagocytic,
-*M12 strains associated with post strep. glomerulonephritis (PSGN)
2. Exotoxins A-C; act as *superantigens and cause the *fever and rash we see in scarlet fever
3. Capsule; anti phags (of hyaluronic acid)
-Also has streptokinase, a DNAse, and hyaluronidase which all serve to break down tissue enabling spread |
|
|
Term
| What are the diseases for Strep pyogenes (4)? |
|
Definition
1. Pharyngitis; duh
2. Scarlet fever; pharyngitis followed by *sandpaper rash, *strawberry tongue, nausea/vomiting
3. Pyoderma/impetigo; with "honey crusted lesions" (same as with staph and have to use catalase to diff) (impetigo is a type of pyoderma; pus producing cutaneous lesion)
4. Necrotizing fascitis and other skin infections |
|
|
Term
| What are the **sequellae to the primary S. pyogenes infections**? |
|
Definition
-Often secondary to simple Strep throat
5. Rhematic fever; antibodies to heart 2 weeks after
-Hypersensitivity type II (antibody attack of cells)
6. Acute glomerulonephritis (M12 serotype); edema, hypertension, smokey urine
-Type III hypersensitivity (complex mediated) |
|
|
Term
| What is the antibody that leads to the rheumatic fever? |
|
Definition
-Antibodies to streptolysin O (ASO)
-We can test this in a titer |
|
|
Term
| How do we treat Strep pyogenes? |
|
Definition
-B-lactams
-Macrolides in case of penicillin allergy |
|
|
Term
Define (class);
Folliculitis
Boil
Furuncle
Carbuncle
Osteomyelitis
Erysipelas
Cellulitis
Impetigo (pyoderma) |
|
Definition
Caused mostly by Staph aureus;
-Folliculitis; infection of the hair follicle
-Boil; deep coalesced folliculitis
-Furuncle; a boil
-Carbuncle; same but larger
-Osteomyelitis; bone infection
Caused mostly by Strep pyogenes;
-Erysipelas; dermis infection with blockage of lymphatics (commonly on the cheeks)
-Cellulitis; fat/subQ infections
-Impetigo is caused by both; erythematous with pus |
|
|
Term
| What should we know about Strep agalactiae? |
|
Definition
-***#1 cause of neonatal septicemia and meningitis***; from vagina, esp. with harsh labor
For ID;
-Beta hemolytic
-Bacitracin resistant
-CAMP test positive (arrow head on blood agar)
-Major virulence is capsule and hemolysin |
|
|
Term
| What are the characteristics of Streptococcus pneumoniae? Where do we find it and how is it transmitted? |
|
Definition
-alpha-hemolytic
-*Optochin sensitive (to diff from viridans; also viridans has no capsule)
-Lancet shaped **diplococci with **capsule
-Lysed by bile
-Found in the upper resp. (often normally) and transmitted by droplets (but is not considered highly communicable) |
|
|
Term
| What is the virulence of Strep. pneumoniae? |
|
Definition
1. *Capsule; by far the most important
Also;
2. IgA protease; helps in invasion
3. Pneumolysin; pore forming |
|
|
Term
| What are the predisposing factors for Strep. pneumoniae? |
|
Definition
-Influenza
-COPD
-CHF
-Alcoholism
-Asplenia; susceptible to all the capsular antigens |
|
|
Term
| What are the diseases for Strep. pneumoniae? |
|
Definition
1. Typical pneumonia; blood tinged (*rusty) sputum, fever and chills, *lobar consolidated infection (for X-ray)
2. Adult meningitis; CSF will have high WBC, low glucose, and high protein contents
3. Otitis media and sinusitis in children
-***Most common cause of all three*** |
|
|
Term
| How do we diagnose and treat Strep. pneumoniae infections? How can we prevent? |
|
Definition
-*Quellung reaction; positive (shows capsule with addition of type specific antibodies)
-Latex particle agglutination is new and better
-Pneumonia; macrolides (like erythromycin)
-Meningitis; a cephalosporin (B lactam for meningitis)
-Otitis media; B lactams
Pediatric vaccine; PCV (pneumococcal capsular vaccine)
-With seven serotypes
Adult; PPV (pneumococcal polysaccharide vaccine)
-23 serotypes |
|
|
Term
| What are Viridans Streptococci? What differentiates them? |
|
Definition
-They are Strep that endogenous to the **mouth that fall outside of the grouping system (Lancefield serotyping)
-The important ones are *S. mutans & sanguis
-They are differentiated from the rest of Strep because they are *alpha hemolytic (S. pneumoniae is too) and *optochin resistant |
|
|
Term
| What are the diseases, symptoms, and predisposing factors for Viridans Streptococci? |
|
Definition
1. **Endocarditis (*subacute); is the number one cause and is often associated with damaged/prosthetic heart valves, and also with dental work or very poor dental hygiene (and often with both together)
-Is often associated with *splinter hemorrhages under the nails, clubbing, spots on hands, feet, retina, fatigue, etc.
2. Dental caries; S. mutans is the one that makes *plaque |
|
|
Term
| What is the pathogenesis of Viridans Streptococci? How do we treat it? |
|
Definition
-It has *dextran which allows it to form its thick biofilm; on teeth and damaged heart valves
-Treat with penicillin G and aminoglycosides
-Must prophalax patients getting dental work who have damaged heart valves |
|
|
Term
Define (class);
Endarteritis
Phlebitis
Osler nodes |
|
Definition
-Endarteritis; artery infection (S. aureus)
-Phlebitis; vein infection (S. aureus)
-Osler nodes; painful spots on pads of fingers ant toes, disappear within hours; associated with *endocarditis
-Janeway lesions; same, but painless and days
-Roth spots; on retina; endocarditis sign |
|
|
Term
| (Random for class); What are the top three causes of acute otitis media and acute bacterial rhinosinusitis (sinus infections)? |
|
Definition
1st. Strep pneumoniae
2nd. Haemophilus influenzae
3rd. Moraxella catarrhalis |
|
|
Term
| What are the members and identification strategy for the Enterococcus genus? |
|
Definition
Members; E. faecalis & faecium, both in GI, urethra, & vag.
-Also known as group D Strep.
Identification; Cat neg, PYR+, varied hemolysis (usually *gamma), ***hydrolyzes esculin and is bile and salt tolerant*** (turns **bile esculing agar black) |
|
|
Term
| What diseases do the Enterococci cause? How do we treat and what are the problems with treatment? How do they arise? |
|
Definition
1. *Urinary and biliary infections; because bile/salt tolerant
2. **Infective (subacute) endocarditis; damaged heart valves + GI surgery (Viridans Strep are + dental work)
-Very resistant, and some **vancomycin resistant strains are impossible to treat
-VanA strains have a D-ala-D-lac instead of D-ala-D-ala
-Best to prophylax with penicillin prior to GI/urinary work |
|
|
