Aerobic Cocci Flashcards
Pathogenicity of Strep agalactiae
Group B specific antigen, infections in newborns and women who become ill after childbirth-endometritis and wound infections.
Pathogenicity of Strep pyogenes
Bacterial pharyngitis, pyoderma infections, rheumatic fever invasive Streptococcal infections
Pathogenicity of Strep pneumoniae
CA - Pneumonia, sinusitis, otitis media, bacteremia and meningitis
Pathogenicity of Strep viridians
subacute bacterial endocarditis, immunocompromised meningitis, abscesses, osteomyelitis
Pathogenicity of Enterococcus
UTI’s, wound infections, interabdominal abscesses
Pathogenicity of Pedicoccus
Isolated from saliva, stool, urine, and wounds, rarely causes disease but septicemia and bacteremia have been reported
Pathogenicity of Strep milleri (anginosus)
Abscesses and other pyogenic infections
Pathogenicity of Staph aureus
Skin and wound infections, food poisoning, scalded skin syndrome, toxic shock syndrome
Pathogenicity of Staph epidermidis
Predominantly hospital-acquired, with catheterization prosthetic heart valve implantation
Pathogenicity of Staph saprophyticus
UTI’s in young sexually active females
Pathogenicity of Micrococcus
Rarely causes infections
Pathogenicity of Stomatococcus
Opportunistic pathogen isolated most often from drug abuse
Colony and microscopic morphology of staphylococcus
White, smooth colonies, may or may not produce pigment or hemolysis, GPC in clusters or tetrads
Colony and microscopic morphology of beta Strep groups A & B
Group A - large zone of beta hemolysis, tiny PP colonies, gram pos. cocci in chains. Group B - narrow zone of beta hemolysis, small white colonies, gram pos. cocci in chains
Colony and microscopic morphology of Enterococcus
Small white colonies with disappearing borders, can show any hemolysis, gram pos cocci in chains
List tests to distinguish between Staphylococcus aureus and other Staphylococcus species
Staph aureus has a positive coagulase test and latex
What test distinguishes Staphylococci from Streptococci
Catalase
Discuss the types of hemolysis and what is happening to the RBCs
Beta - complete clearing of RBCs (clear, yellow)
Alpha - partial lysis of RBCs (Green)
Gamma - No change in background
Does beta hemolysis always indicate the presence of Streptococci
no
3 ways to identify enterococcus
Automated systems, PYR, Bile esculin and 6.5% NaCl
Describe the leucine aminopeptidase test (LAP) and list the organisms it differentiates.
Leucine aminopeptiase is a peptidase that hydrolyzes peptide bonds adjacent to a free amino group. Because LAP reacts most quickly with Leucine. The addition of DMACA causes a red color to develop in pos. tests.
- LAP differentiates Aerococcus and Leuconostoc from other GPC.
- LAP positive for strept, entero, and pediococcus spp.
Significance of vancomycin resistant Enterococcus, including how the genetic material is acquired
Widespread use of vancomycin has led to VRE. There are two choices for VRE: synercid and linezolid. Proteins encoded by vanA and vanB genes give its resistance. Enterococcus spp containing the Van A phenotype are highly resistant. Modify peptidoglycan termini, N-acyl-D-Ala-D-Ala, involved in cross-linking to N-Acyl-D-Ala-D-Lactate.
Compare and contrast hospital aquired MRSA and community aquired MRSA
Hospital: HA-MRSA is the name for infections acquired while in the hospital recently, long term care, dialysis, or indwelling devices
Community: CA-MRSA is the name for infections amongst people who lack traditional healthcare associated risk factors. Outbreaks have been among athletes, correctional facility inmates, military recruits in barracks, pediatric patients and tattoo recipients.
Virulence factors for Streptococcus
- M protein
- Enzymes (Streptolysin O and S)
- DNAase A-D
- Streptokinase A and B
- Pyrogenic toxins A-C
- Capsule
Virulence factors for Staphylococcus
- Enterotoxins A, D, F
- Exfoliative toxin
- Cytolytic toxin (affect WBCs and RBCs)
- Enzymes (coagulase, hyaluronidase, lipase)
- Protein A (bind to Igs)
- Mec A gene/PBP₂
Give the principle of the rapid direct antigen Streptococcal test for beta-hemolytic group A Streptococcus done on throat swabs for slide agglutination and ELISA
Slide agglutination: Extracts C carbohydrate, which is a specific group antigen. This is done by heat or acid and it agglutinates with specific antisera.
ELISA: Uses specific antibodies which matches to strep groups and another antibody with enzyme tag is added to enhance.
The historical capsular swelling used for the rapid ID of Strep pneumoniae is also know as
Quellung or Neufeld reaction
With Strep pneumoniae, virulence is directly proportional to the?
The polysaccharide capsule and its antiphagocytic activity
Name 3 tests used in identifying Streptococcus pneumoniae. Strep pneumonia is A BOSS mnemonic
Optochin, automated procedures, bile solubility, Quellung, Antigen typing
What substance present on the cell wall of Group A Beta Strep is responsible for virulence of the organism?
M protein
What role does Strep pyogenes play in rheumatic fever?
- Antibodies attach to heart valves, and tissue damage occurs
- Exotoxin damage
- Invasion of heart tissue
Why does someone who has had a Strep throat infection get another?
80 different M protein serotypes (each with a unique Ab response)
Describe a secondary condition to a Strep throat infection.
Glomerulonephritis
What is the antibiotic of choice in treating group A beta-hemolytic Streptococci infections? What if the patient is allergic to the drug of choice?
Penicillin, Erythromycin
Describe Staphylococcal food poisoning.
Enterotoxins A and D cause symptoms to appear in 2 to 8 hours and resolve within 6-8 hours
Explain the difference between the slide and tube coagulase tests and which type of coagulase does each measure?
Bound Coagulase or slide coagulase: detects enzyme that connects fibrinogen to fibrin on surface of cell, clumping factor.
Free Coagulase or tube - Detects enzyme that is excreted away from cell wall, staphylocoagulase.
Discuss the different testing methodologies used in the ID of MRSA.
Agglutination-PBP₂ Automated for Mec A gene Oxacillin Cefotoxin MRSA media (CHROM agar)
What is the gram stain and morphology of Neisseria?
Gram Neg diplococci
What antibiotics are in Modified Thayer Martin plates and what is the purpose of each?
Vancomycin: inhibits GPC
Colistin: inhibits GNR
Trimethoprim: Prevents Proteus swarming
Nystatin: Prevents growth of Fungi
What tests are commonly used to differentiate species of Neisseria?
N. gonorrhoeae: growth only on chocolate plate, glucose pos, other sugars neg.
N. meningitidis: growth on BAP and chocolate plate, glucose/maltose pos, other sugars neg.
Discuss the pathogenicity of Neisseria meningitidis
May have a capsule, endotoxin production, pili and IgA protease, all of which contribute to the virulence and pathogenicity.
Indicate the significance of the meningocococcus vaccination. Discuss the serogroups that covered by the vaccination and those that are not.
Used on people ages 11 to 55 years and covers all serogroups except B.
Associate the specific serogroup of Neisseria meningitidis with Waterhouse-Frederichsen syndrome.
Serogroup B
What non-culture tests are available to detect Neisseria gonorrhoeae.
Fluorescent test, direct micro exam, immunologic, nucleic acid probe
Describe two methods of performing the oxidase test and the chemicals involved
Filter paper or direct plate, using the reagent 1% dimethyl or tetra methyl-p-phenylene diamine dihydrochloride.
-put organism on filter paper followed by reagent or vice versa
Pathogenicity of Moraxella catarrhalis
Upper respiratory, middle ear, and eye infections.
Identify tests and their methodology used in the ID of Moraxella catarrhalis
Organisms will grow on BAP and CHOC, smooth hockey puck colonies, asaccharolytic and may be differentiated by positive DNase and butyrate esterase reactions.
Compare and Contrast the different Neisseria meningitidis serogroups and disease states they cause.
There are 13 meningococcal encapsulated serogroups, but strains A, B, C, Y and W-135 are most often associated with epidemics.
Serogroup A-
Serogroup B and C-
Serogroup Y-
Serogroup W-135-
Serogroup A- Pandemics
Serogroup B and C- Most common in USA, with group B involved in community acquired
Serogroup Y- Primarily causes menigococcal pneumonia
Serogroup W-135- Often responsible for invasive disease
Describe the principle of the Superoxol test and organize the different organisms it tests for and their expected results.
The superoxol test uses 30% H₂O₂ and is the same as the catalase test. Colonies of N. gonorrhoeae produce immediate vigorous bubbling (positive)
Colonies of N. meningitidis and N. lactamica produce weak delayed bubbling (negative).
Principle of catalase test
The enzyme catalase mediates the breakdown of hydrogen peroxide into oxygen and water. Bubbles is positive
Principle of hippurate hydrolysis test
Detect the ability of bacteria to hydrolyse substrate hippurate into glycine and benzoic acid by action of hippuricase enzyme. Purple = positive
Serological Strep grouping
Grouping Streptococcus depending on catalase-negative, coagulase-negative bacteria based on the carbohydrate composition
Principle of PYR test
Enzyme L-pyrrolidonyl arylamidase hydrolyzes the L-pyrrolidonyl- β-naphthylamide substrate to produce a β-naphthylamine. Pink = positive (enterococcus)
Principle of Bile solubility test
Based on the observation that Streptococcus pneumoniae will visibly lyse with 2% or 10% sodium. Clear = positive
Principle of Optochin test
Inhibits the growth of Streptococcus pneumoniae at very low concentration. No growth around disk = suseptible
Principle of 6.5% NaCl test
This test determines whether the microbe can grow in a medium containing 6.5% sodium chloride (NaCl). Yellow is positive (Enterococcus) . Purple is neg (nonenterococcus)
Principle of Bile esculin test
Based on the hydrolysis of esculin into glucose and esculetin. More than half the media is brown = positive.
Principle of CAMP test
Produce a diffusible extracellular hemolytic heat-stable protein (CAMP factor) that acts synergistically with the beta-lysin. Arrowhead is positive
What is the principle behind the latex agglutination testing for Staphylococcus species:
Plasma coated latex particles that contain fibrinogen and non-specific IgG on surface. Staph aureus has clumping factor that reacts with the fibrinogen and Protein A that will react non-specifically with the FC portion of the IgG.
Morphology of Staph aureus
large, round, golden-yellow colonies, GPC, beta hemolysis
Morphology of Staph saprophyticus
Glossy, smooth, and convex. Buttery colony that may be white, cream, yellow, or orange. Gamma
Morphology of Beta hemolytic strep
White-greyish color and are surrounded by a zone of β-hemolysis
Morphology of Alpha hemolytic strep
White-greyish color and are surrounded by a zone of alpha (green) hemolysis
Morphology of non hemolytic strep
White-greyish color and are surrounded by a zone of gamma(no lysis) hemolysis
Morphology of Enterococci
similar to strep colonies
Morphology of Strep pneumoniae
Small grey, dip down like donut, alpha hemolysis
Organisms most frequently isolated from Premature baby
Staphylococcus aureus and Candida
Differentiate between community and hospital acquired pneumonia and organism associated with each.
Community - Strep pneumoniae
Hospital - P. aeruginosa, Enterobacter
Strep pyogenes tests
Hemolysis: Bacitracin: SXT: CAMP test: Hippurate Hydrolysis: LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Hemolysis: Beta Bacitracin: S SXT: R CAMP test: = Hippurate Hydrolysis: = LAP: + PYR: + Bile Esculin: = NaCl(6.5%): = Optochin: R Vancomycin: S Bile Solubility: =
Strep agalactiae tests
Hemolysis: Bacitracin: SXT: CAMP test: Hippurate Hydrolysis: LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Hemolysis: Beta Bacitracin: R SXT: R CAMP test: + Hippurate Hydrolysis: + LAP: + PYR: = Bile Esculin: = NaCl(6.5%): V Optochin: R Vancomycin: S Bile Solubility: =
Enterococcus tests
Hemolysis: Bacitracin: SXT: CAMP test: Hippurate Hydrolysis: LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Hemolysis: Beta/Alpha/Gamma Bacitracin: R SXT: R CAMP test: = Hippurate Hydrolysis: V LAP: + PYR: + Bile Esculin: + NaCl(6.5%): + Optochin: R Vancomycin: S/R Bile Solubility: =
Strep equines/bovis tests
Hemolysis: Bacitracin: SXT: CAMP test: Hippurate Hydrolysis: LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Hemolysis: Beta Bacitracin: V SXT: S CAMP test: = Hippurate Hydrolysis: = LAP: + PYR: = Bile Esculin: = NaCl(6.5%): = Optochin: R Vancomycin: S Bile Solubility: =
Strep pneumoniae tests
Hemolysis:
Bacitracin:
SXT:
Hippurate Hydrolysis: LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Hemolysis: Alpha
Bacitracin: R
SXT: S
Hippurate Hydrolysis: = LAP: + PYR: = Bile Esculin: = NaCl(6.5%): = Optochin: S Vancomycin: S Bile Solubility: +
Strep viridians tests
Hemolysis:
Bacitracin:
SXT:
LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Hemolysis: Alpha
Bacitracin: V
SXT: S
LAP: + PYR: = Bile Esculin: = NaCl(6.5%): = Optochin: R Vancomycin: S Bile Solubility: =
Strep milleri tests
Bacitracin:
LAP: PYR: Bile Esculin: NaCl(6.5%): Optochin: Vancomycin: Bile Solubility:
Bacitracin: R
LAP: + PYR: = Bile Esculin: = NaCl(6.5%): = Optochin: R Vancomycin: S Bile Solubility: =
Abiotrophia tests
Hemolysis:
LAP:
PYR:
Vancomycin:
Hemolysis: Alpha/Gamma
LAP: +
PYR: +
Vancomycin: S
Granulicatella tests
Hemolysis:
LAP:
PYR:
Vancomycin:
Hemolysis: Alpha/Gamma
LAP: +
PYR: +
Vancomycin: S
Aerococcus tests
Hemolysis:
Hippurate Hydrolysis:
LAP:
PYR:
Bile Esculin:
Vancomycin:
Hemolysis: Alpha
Hippurate Hydrolysis: V
LAP: =
PYR: +
Bile Esculin: V
Vancomycin: S
Helocococcus tests
Hemolysis:
Hippurate Hydrolysis:
LAP:
PYR:
Bile Esculin:
Vancomycin:
Hemolysis: Alpha/Gamma
Hippurate Hydrolysis: =
LAP: =
PYR: +
Bile Esculin: =
Vancomycin: S
Leuconostoc tests
Hemolysis: LAP: PYR: Bile Esculin: Vancomycin:
Hemolysis: Gamma LAP: = PYR: = Bile Esculin: + Vancomycin: R
Gemella tests
Hemolysis:
Hippurate Hydrolysis: LAP: PYR: Bile Esculin: NaCl(6.5%):
Vancomycin:
Hemolysis: Alpha/Gamma
Hippurate Hydrolysis: = LAP: + PYR: + Bile Esculin: = NaCl(6.5%): =
Vancomycin: S
Pediococcus tests
Hemolysis:
Hippurate Hydrolysis:
LAP:
Vancomycin:
Hemolysis: Alpha
Hippurate Hydrolysis: +
LAP: =
Vancomycin: R
Tetragenococcus tests
Hemolysis:
Hippurate Hydrolysis:
LAP:
Vancomycin:
Hemolysis: Alpha
Hippurate Hydrolysis: +
LAP: =
Vancomycin: S
Lactococcus tests
Hippurate Hydrolysis:
LAP:
Vancomycin:
Hippurate Hydrolysis: +
LAP: +
Vancomycin: S
Staph aureus tests
Hemolysis: Catalase: Coagulase: Polymyxin B: Novobiocin: PYR: Oxidase: Lysosome: Lysostaphin: Bacitracin:
Hemolysis: BETA Catalase: + Coagulase: + Polymyxin B: S Novobiocin: S PYR: = Oxidase: = Lysosome: R Lysostaphin: S Bacitracin: R
Staph saprophyticus tests
Catalase: Coagulase: Polymyxin B: Novobiocin: PYR: Oxidase:
Catalase: + Coagulase: = Polymyxin B: S Novobiocin: R PYR: = Oxidase: =
Staph epidermidis tests
Catalase: Coagulase: Polymyxin B: Novobiocin: PYR: Oxidase:
Catalase: + Coagulase: = Polymyxin B: R Novobiocin: S PYR: = Oxidase: =
Staph haemolyticus tests
Catalase: Coagulase: Polymyxin B: Novobiocin: PYR: Oxidase:
Catalase: + Coagulase: = Polymyxin B: S Novobiocin: S PYR: + Oxidase: =
Staph hominis tests
Catalase: Coagulase: Polymyxin B: Novobiocin: PYR: Oxidase:
Catalase: + Coagulase: = Polymyxin B: S Novobiocin: S PYR: = Oxidase: =
Staph warneri tests
Catalase: Coagulase: Polymyxin B: Novobiocin: PYR: Oxidase:
Catalase: + Coagulase: = Polymyxin B: S Novobiocin: S PYR: = Oxidase: =
Micrococcus tests
Catalase: Coagulase: Oxidase: Lysosome: Bacitracin:
Catalase: + Coagulase: = Oxidase: + Lysosome: S Bacitracin: S
Strep pyogenes
Bacitracin:
SXT:
Bacitracin: S
SXT: R
Strep agalactiae
Bacitracin:
SXT:
Bacitracin: R
SXT: R
Strep equines/bovis
Bacitracin:
SXT:
Bacitracin: V
SXT: S
Enterococcus
Bacitracin:
SXT:
Bacitracin: R
SXT: R
Strep pneumoniae
Bacitracin:
SXT:
Bacitracin: R
SXT: S
Strep viridians
Bacitracin:
SXT:
Bacitracin: V
SXT: S
Strep pneumoniae colony morphology
Alpha hemolysis, older colonies-coinlike appearance, mucoid, gram pos. diplococci-lancet.
Principle of bacitracin test
Used to determine the effect of a small amount of bacitracin on an organism. Strep pyogenes is usually susceptible.
Principle of Carbohydrate utilization test
Carbohydrate utilization test is used to determine whether or not a bacteria can utilize a certain carbohydrate which produces acid. Red = negative
Principle of Cefinase test
Rapid testing of isolated colonies of Neisseria gonorrhoeae, Staphylococcus and Enterococcus species as well as Hameophilus influenzae.
Detects beta lactamases
Principle of beta lactamase test
Detects the enzyme beta-lactamase, which confers penicillin resistance to various bacterial organisms
