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Microbiology > Gram (+) and Gram (-) Cocci > Flashcards

Gram (+) and Gram (-) Cocci Flashcards

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1
Q

Staphylococci

A

Gram Pos
Resistant to heat and drying
Persists on fomites
Bunch of Grapes
Found on skin/nasal flora, common wound or nosocomial infections
Faculative anaerobes
Distinguishing factor from streptococci: Pos catalase test (forms bubbles)

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2
Q

Streptococci

A

Gram pos
Divides in chains (snake of balls). Spherical cocci. COmmonly in pairs.
Distinguishing factor from streptococci: NEGATIVE catalase test
Fastidous (studpid weak…needs enriched media, sensitive to drying/heat)
Aerotolerant anaerobes (can grow anaerobically but prefer aerobic).
Classify based on hemolysis pattern on blood agar and cell wall antigen.
Categorize through hemolytic patterns (BAY) or Lancefield categorizations (A,B, D, None)

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3
Q

Enterococci

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A

Lancefield Group: D
Hemolysis: Gamma (Or alpha, tho more rare)
Gram: Pos
Hardiness:
Shape:
Found where: Normal GI flora
Aerobicity:
Distinguishing tests: Bile Esculin Hydrolysis slant: turns from red to black if enterococci grows in it. has 40% bile in it. It also lasts in high salt concentrations (6.5% NaCl broth survival differentiates S. bovis (Group D strep) from enterococci).
Antibiotic resistance: Is sensitive to ampicillin and gentamycin (or penicillin and streptomycin). Second line defence is vancomycin. Inc ase of vancomycin resistant enterococci (VRE), you must use linezolid, tigecycline, or pristinamycin
Clinical manifestations:
Virulence Factors: Not really virulent. However, can cause urinary or biliary infection or intraabdominal abscesses in immune compromised peoplez. It can also lead to endocarditis (or bacteremia/sepsis)
Antibiotic resistance: Resistant to Vancomycin (more so with E faecium than E faecalis), but also has inherent resistance.

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4
Q 
Staphylococci aureus
Gram:
Hardiness:
Shape/aestetic:
Found where:
Aerobicity:
Distinguishing tests:
Virulence Factors:
Clinical manifestations:
A

Gram: Pos
Hardiness: Resistant to heat and drying. Persists on fomites
Shape/aestetic: Bunch of Grapes (mic), yellow circles (agar)
Found Where: skin/NASAL flora, common wound or nosocomial infections
Aerobicitiy: Faculative anaerobes
Distinguishing factor from streptococci: Pos catalase test (forms bubbles). Coagulase positive (thickens fluid)
Virulence Factors: Capusule, protein A (inverse antibodies…bind via Fc), several adhesins, invasins to digest connective tissue (staphylokinase, collegase, lipase), cytotoxins (hemolysins punch hole into rbcs…..and PVL, produced by CA MRSA, lyses pmns), superantigen toxins (exotoxins…toxins secreted from bacteria and sent to rest of body) which activate polyclonal T cells…multiorgan impact
Clinical manifestations:Clinical manifestations: skin and soft tissue infections (ssti’s): Furuncles (small us-filled local infections)
Carbuncles: Larger skin abscesses
Impetigo: spreading, crusted skin infections
Cellulitis: deep skin infection
All will result in surgical debridement in addition to systemic antibiotic treatment fro abscesses. note A skin infection WILL defintiely spread (metastasis) to other organs…
1. Osteomyelitis (most common cause of bone infection in kiddies)
2. Septic joint (KIDDIE!!!!)
3. Pneumonia
4. Acute endocarditis (heart valve infection)
5. blood stream

Staph aureus can also cause infectionsvarious toxinoses:

  1. Toxic shock syndrome from TSST-1 (desquammation of hands and soles) leads to high fever, hypotension, rash, multiorgan failure
  2. Food poisoning (heat stable enterotoxins…acute gi distress….happens immediately)
  3. Scalded skin syndrome from exfoliatin…blisters (bullae) happen in newborn babies.
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5
Q 
Staphylococci epidermidis
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Virulence Factors:
Clinical manifestations:
Antibiotic resistance:
A

Gram: Pos
Hardiness: Resistant to heat and drying. Persists on fomites
Shape: Bunch of Grapes
Found Where: SKIN/nasal flora, common wound or nosocomial infections
Aerobicitiy: Faculative anaerobes
Distinguishing factor from streptococci: Pos catalase test (forms bubbles). Neg coagulase test.
Virulence factors: Not as virulen as s. aureus. Produces slime that adheres to bioprosthetic materials and acts as antibiotic barries. Catheter/edical device infections. Most resistant to penicillin and methicillin

Antibiotic resistance: Novobiocin sensitive.

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6
Q 
Staphylococci saprophyticus
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
A

Gram: Pos
Hardiness: Resistant to heat and drying. Persists on fomites
Shape: Bunch of Grapes
Found Where: skin/nasal flora, common wound or nosocomial infections. NORMAL VAGINAL FLORA
Aerobicitiy: Faculative anaerobes
Distinguishing factor from streptococci: Pos catalase test (forms bubbles). Neg coagulase test

Antibiotic resistance: Novobiocin resistant. Note that it is sensitive to penicillin G

Clinical manifestations: UTI, cystitis

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7
Q

Streptococcus pyogenes

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A

Lancefield Group: A
Hemolysis: Beta
Gram Pos
Hardiness:
Shape:
Found where: contact, droplets, food, throat..does not last on fomites long. Enters through pharynx
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
1. Streptococaal pharyngitis (strep throat) and scarlet fever on chest
2. Streptococcal skin infection (impetigo) or necrotizing fasciitis. Treat with penicillin. (if staph…naw)
3. Streptococcal toxic shock syntdrome due to superantigen pyrogranic exotoxin mediated organ failure.
4. Antibody mediated post-infection sequelae of Group A streptococcal infections:
A. Heart and joint: acute rheumatic fever (teh antibodies react to heart proteins since they resemble the M protein from s. pyrogenes.)
B. Kidney: Acute poststreptococcal glomerulonephritis (APSGN) ka type 3 hypersensitivity…ab-ag complex screws up kidneys. Will have blood in urine
Virulence Factors: M protein (80 types), which is needed for infection and each M protein can cause a infection (you can develop antibodies for one M protein, and still be susceptible to the other 79). Streptolysin O and S lyses rbcs (Antistreptolysin S and O titers (ASO)). Streptococcal pyrogenic exotoxins A, B, C. Streptokinase
Antibiotic resistance: Treat with penicillin. Sensitive to bacitracin

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8
Q

Streptococcus agalactiae

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A 
Lancefield Group: B
Hemolysis: Beta
Gram: Pos
Hardiness:
Shape:
Found where: female reproductive tract
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations: NEONATAL SEPSIS, meningitis, pneumonia. Treat during baby delivery (intrapartum) if positive for group B strep (s. agalactiae)
Virulence Factors:
Antibiotic resistance: Resistant to bacitracin
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9
Q

Streptococcus pnemoniae

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A

Lancefield Group:
Hemolysis Alpha
Gram:
Hardiness:
Shape: lancet shaped arrannged as diplococci. Shiny
Found where: Nasopharynx. Doens’t survive long in habitiat.
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations: Those who have compromised spleen…otherwise, pneumonia, otitis media (middle ear infection), meningitis, bacteremia and sepsis
Virulence Factors: POLYSACCHARIDE CAPSULE (helps it escape our immune system. More capsule = more severity in danger). It’s antiphagoctic and antigenic.
Antibiotic resistance: Sensitive to optochin. also note it has quellung (swelling) rection when put in sera. Resistance to penicillin. Resistance in general caused by PBP gene transmission. Sensitive to 3rd gen cephaosporins (cefotaxime and ceftriaxone). Vaccines used: PPV (polysach vaccine) and PCV13 (conjugate vaccine…more effective and newest).

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10
Q

Streptococcus viridans (S. mitis, S. mutans, S. oralis, S. salivarus, S. sanguis, S. milleri)

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A 
Lancefield Group:
Hemolysis:
Gram: Pos
Hardiness:
Shape:
Found where: mouth (gums, teeth)
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations: dental caries. otherwise not invasive. If enters blood through cut: subacute (slower) endocarditis...growth on heart lining or valves. Note that staph infections lead to acute version of it. 
Virulence Factors:
Antibiotic resistance:
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11
Q

Streptococcus bovis

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A 
Lancefield Group: D
Hemolysis: Gamma (and sometimes alpha)
Gram: Pos
Hardiness:
Shape:
Found where: NORMAL GI FLORA
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations: GI malignancy and colon cancer
Virulence Factors:
Antibiotic resistance: Gets wrecked by penicillin
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12
Q

Neisseria

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
A 
Lancefield Group:
Hemolysis:
Gram: Neg
Hardiness: Sensitive to heat and drying like pnemoncocci
Shape: kidney shaped, diplococci. 
Found where: Located with PMNs
Aerobicity: Aerobic
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
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13
Q

Neisseria gonorrhoeae

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
Epidemiology/pathogeneisis:
A

Second most common STI in US (chlamydia = number 1).

Lancefield Group:
Hemolysis:
Gram: Neg
Hardiness: Has FANCY gene conversion and phase, allowing them to easily evade our immune system variastion mechs
Shape: UNENCAPSULATED, has heterogenous antigens…Pili (attaches to host), OPA (opacity proteins), and LOS (endotoxin like LPS)…all 3 of these can be chaneged in sequence, allowing for immune system evasion
Found where:
Aerobicity:
Distinguishing tests: Pus specimens searching for gram neg diplococci. grow specifically in thayer-martin medium plate (chocolate agar mod that suppresses normal flora growth). Also note Oxidase positive. Can also use NAATs (nucleic acid amplification tests) (primary diagnosis method). Diagnose with oxidase positive, gram stain of csf, blood, skin, or nose. Also not is can use both glucose and maltose, but gonorrhea can only use glucose.
Antibiotic resistance:
Clinical manifestations:
1. Genitourinary tract infections (fallopian tube infection)
2. Opthalmia neonatorum (baby eye crust/grime infection)
3. Blood stream invation leads to disseminated gonoccoccal infection (DGI), which can lead to septic arthritis (SEPTIC JOINT, ADULT!!!!) in young sex active adults
4. Pharyngitis and rectal infections
Virulence Factors: Has IgA protease, which helps infect the mucosa
Antibiotic resistance: Treat with erythromycin or ceftriaxone for the opthalmia neonatorum
Epidemiology/pathogeneisis: STD. attacks mucous membranes (Eye, GI, Gut, rectum). Affects late teens/young adults. YOU WILL SEE PUS and fibrosis. Man, especially females, are asymptomatic
Treatment: Ceftriaxome, or doxycycline to cover possible chlamydial infection (they travel together)

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14
Q

Neisseria meningitidis

Lancefield Group:
Hemolysis:
Gram:
Hardiness:
Shape:
Found where:
Aerobicity:
Distinguishing tests:
Antibiotic resistance:
Clinical manifestations:
Virulence Factors:
Antibiotic resistance:
Treatment:
Epidemiology
A

One of most common cause of bacterial meningitis

Lancefield Group:
Hemolysis:
Gram: Neg
Hardiness:
Shape: ENCAPSULATED
Found where:
Aerobicity:
Distinguishing tests: Diagnose with oxidase positive, gram stain of csf, blood, skin, or nose. Also not is can use both glucose and maltose, but gonorrhea can only use glucose. Can also do latex agglutination test for capsule testing.
Antibiotic resistance:
Clinical manifestations: Menincococemia (petechial rash involved). Also expect meningitis (pus will be in CSF. Expect neuro effects, vomiting, altered mental state). Also expect fulminant septicEMIA (LOS-mediated septic shock…so, large purplish blotchy hemorrhages)
Virulence Factors: Pili, LOS, Opa, IgA protease, Iron extraction system (all like N. gonerria)
Antibiotic resistance:
Treatment: Ceftriaxone or cefotaxime. Large dose of penicillin or ampicillin. Also give propholactic rifampin to all those in contact with patient. Vaccine use = trumenba or Bexsero
Epidemiology: Occurs in waves. Affects young health individualts

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Microbiology (11 decks)

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