SEMR: Gram (+) cocci Flashcards by JHOANNA LYNN LUMBOY

peptidoglycan layer:
gram +=
gram -= single layered

multilayered

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peptidoglycan layer:
gram += multilayered
gram -=

single layered

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teichoic acids:
gram +=
gram -= absent

present in many

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teichoic acids:
gram += present in many
gram -=

absent

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GRAM +
peptidoglycan layer:
teichoic acids:
periplasmic space:
outer membrane:
LPS content:
lipid and lipoprotein:

multilayered
present in many
absent
absent
none
low

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GRAM -
peptidoglycan layer:
teichoic acids:
periplasmic space:
outer membrane:
LPS content:
lipid and lipoprotein:

single layered
absent
present
present
high
high

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gram +
catalase +
2 families

micrococcaceae
staphylococcaceae

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gram +
catalase -
2 families

streptococcaceae
enterococcus

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determinant in development of staphylococcal infections (3)

virulence
size of inoculum
status of host’s immune system

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Gram (+) cocci arranged in tetrads or clusters
Facultative anaerobes
Catalase positive
Oxidase Negative
Non-motile
Grows in 7.5-10% NaCl

Staphylococci

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only Staphylococci that is obligate anaerobe

s. saccharolyticus

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Test the ability of the organism to breakdown of H2O2(3%) into oxygen and water.

Catalase Test

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result of test: Copious bubble formation

catalase test

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-Most clinically significant specie of Staphylococci
-Present in various skin surfaces
-Cause of nosocomial or hospital-acquired infections

Staphylococcus aureus

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Virulence Factor: S. aureus

Enterotoxins that are associated to food poisoning
(diarhea, vomiting); reheating contaminated food
will not prevent disease

A, B, D

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Virulence Factor: S. aureus

heat stable exotoxins: include

A-E
G-J

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Virulence Factor: S. aureus

Formerly known as Enterotoxin F (superantigen-activate aggressive immune response)

TSST-1

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Virulence Factor: S. aureus

Causes menstruating-associated TSS (Tampon use)
absorbed through vaginal mucosa

TSST-1

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Virulence Factor: S. aureus

-Also known as epidermolytic toxin
-Causes SSS (Scalded Skin Syndrome or Ritter
disease) and bullous impetigo (large pustules
with erythema

Exfoliative Toxin

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large pustules with erythema

bullous impetigo

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Virulence Factor: S. aureus

Cytolytic Toxins
Destruction of neutrophils and macrophages

Panton-Valentine Leukocidin(γ-Hemolysin)

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Virulence Factor: S. aureus

Cytolytic Toxins
Lyse erythrocytes

Hemolysins (α, β, δ)

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Virulence Factor: S. aureus

Enzymes
Conversion of fibrinogen to fibrin
Bound Coagulase & Free Coagulase

Coagulase (Staphylocoagulase)

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Virulence Factor: S. aureus

Enzymes
Dissolve fibrin clots and may enable spread of
infection.

Fibrinolysin (Staphylokinase)

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Virulence Factor: S. aureus Enzymes Cleaves protein

Protease

Virulence Factor: S. aureus Enzymes Hydrolyzes hyaluronic acid in connective tissues

Hyaluronidase

Virulence Factor: S. aureus Enzymes Hydrolyzes lipids in the skin

Lipase

Virulence Factor: S. aureus Enzymes Binds to the Fcportion of IgG, neutralizes it and block phagocytosis

Protein A

Virulence Factor: S. aureus Enzymes Breakdown of beta-lactamring in penicillin molecule

Beta lactamase (Penicillinase)

infections or Associated Disease mild inflammation of hair follicle

Folliculitis Staphylococcus aureus

infections or Associated Disease large, raised, superficial abscess

Furuncles (boils) Staphylococcus aureus

infections or Associated Disease invasive lesions develop from multiple furuncles, may progress into deeper tissues

Carbuncles Staphylococcus aureus

infections or Associated Disease pustules are larger and surrounded by a small zone of erythema

Bullous Impetigo Staphylococcus aureus

infections or Associated Disease extensive exfoliative (profuse peeling) dermatitis caused by staphylococcal exfoliative or epidermolytic toxin.

Scalded Skin Syndrome (Ritter disease) Staphylococcus aureus

infections or Associated Disease fatal disease characterized by sudden onset of fever, chills, vomiting, diarrhea, muscle aches, and rash, w/c could lead to hypotension and shock.

Toxic Shock Syndrome Staphylococcus aureus

infections or Associated Disease clinical manifestation w/ multiple causes; it is most commonly drug induced, but some cases may have been linked to infections and vaccines.

Toxic Epidermal Necrolysis (TEN) Staphylococcus aureus

Virulence Factor: S. epidermidis Enhances organisms adhesion to implanted medical devices and provides refractoriness to host defense.

Exopolysaccharide “slime” or biofilm

Staphylococci infection and associated disease: Hospital acquired UTI and prosthetic valve endocarditis

Staphylococcus epidermidis

-Adheres to the epithelial cells lining the urogenital tract -Causes UTI in sexually active, young females and in older women with indwelling catheters

Staphylococcus saprophyticus

Coagulase negative (can give (+) slide, but tube negative)

Staphylococcus lugdunensis

Virulence Factor - encodes for oxacillin resistance

Gene mecA Staphylococcus lugdunensis

Virulence Factor Vancomycin resistance

Staphylococcus haemolyticus

Culture Media Enriched isolation of Staphylococci

Blood Agar

Culture Media Selective medium for Gram-positive cocci

Colistin-nalidixic acid or PEA agar

Culture Media Selective and differential for Staphylococcus

Mannitol Salt Agar

catalase + microdase - aerobic growth + anaerobic growth +

staphylococcus

catalase + microdase + aerobic growth + anaerobic growth -

micrococcus

bacitracin, furazolidone, lysostaphin: RESISTANT

staphylococcus

bacitracin, furazolidone, lysostaphin: SENSITIVE

micrococcus

coagulase + DNAse + MSA +

s. aureus

coagulase - DNAse - MSA - novobiocin- SENSITIVE

s. epidermidis

coagulase - DNAse - MSA - novobiocin- RESISTANT

s. saprophyticus

lab test to differentiate s. epidermidis from s. saprophyticus

novobiocin

Bacitracin Susceptibility (Taxo A) Test for the susceptibility to --U Bacitracin.

0.04

Test for the ability of bacteria to convert fibrinogen into fibrin

Coagulase Test

Differentiate Staphylococcus aureusfrom coagulase negative staphylococci

Coagulase Test

Detects bound coagulase “clumping factor”.

Coagulase Slide Test

Coagulase Slide Test S. aureus S. lugdunensis S. schleiferi

Positive

Coagulase Slide Test S. epidermidis S. saprophyticus

negative

Detects free coagulase (staphylocoagulase)

Coagulase Tube Test

-Selective for gram-positive bacteria -inhibit Gram (-) Bacteria.

Colistin-Nalidixic Agar (CNA)/ Phenylethyl Alcohol Agar (PEA)

Colistin-Nalidixic Agar (CNA)/ Phenylethyl Alcohol Agar (PEA) No growth: total inhibition --

E. coli

Colistin-Nalidixic Agar (CNA)/ Phenylethyl Alcohol Agar (PEA) No growth: partial inhibition --

P. mirabilis

-Selective and differential Medium -Contains NaCl (7.5%), D-mannitol, phenol red

Mannitol Salt Agar

Test for the position of cytochrome to produce a dark- blue end product when reacted with Microdase Reagent

Microdase Test (Modified oxidase)

Microdase test:+

micrococcus

Microdase test:-

staphylococcus

Novobiocin Susceptability test for susceptibility to -- μg novobiocin.

5 μg novobiocin.

Test for the ability of the organism to hydrolyze the substrate L-pyrrolidonyl-β-naphthylamide

Miscellaneous (PYR Test)

Positive: Bright color within 5 minutes (pink to cherry-red color after addition of color developer)

Miscellaneous (PYR Test)

Miscellaneous (PYR Test) S. epidermidis S. saprophyticus

Miscellaneous (PYR Test) S. haemolyticus S. lugdunensis

Most -- isolates produce Beta-lactamases (penicillinases) therefore are resisitantto penicillin

S. aureus

Isolates that are resistant to nafcillinor oxacillin

MRSA/MRSE (methicillin-resistant staphylococci)

gold standard for MRSA detection (detection of mecA gene)

Nucleic acid probes/ PCR amplification

(borderline oxacillin-resistant S. aureus)

BORSA

(vancomycin-intermediate S. aureus)

VISA

(vancomycin-resistant S.aureus)

VRSA

Gram (+) cocci arranged in pairs or chains Aerotolerant anaerobes Catalase negative Some are capnophilic Non-motile

Streptococci

stretococci based on Cell Wall Structure

Lancefield grouping

Lancefield: A Common term: group A strep

s. pyogenes

Lancefield: B Common term: group B strep

s. agalactiae

Lancefield: C Common term: group C strep

s. dysagalactiae, s. equi

Lancefield: D Common term: group D NONenterococcus

s, bovis

Lancefield: D Common term: group D ENTEROcoccus

e. faecalis, e. faecium

Common term: pneumococcus

s. pneumoniae

Lancefield: A,C,F,G,N Common term: viridans strep

anginosus, mutans, mitis

streptococci based on Pattern of hemolysis

Brown’s Classification

Syreptococci hemolysis: beta

group a,b,c s. pyogenes s. agalactiae s. dysagalactiae, s. equi

Syreptococci hemolysis: alpha

pneumococcus/ s. pneumoniae

Syreptococci hemolysis: alpha, beta, gamma

group D enterococcus e. faecalis, e. faecium

Syreptococci hemolysis: alpha, gamma

group D nonenterococcus s. bovis

Syreptococci hemolysis: beta, alpha, gamma

viridans strep anginosus, mutans, mitis

Pattern of hemolysis (Brown’s Classification) Partial lysis of RBC’s around colony Greenish discoloration of area around colony

Alpha (α)

Pattern of hemolysis (Brown’s Classification) Complete lysis of RBC’s around colony Clear area around colony

Beta (β)

Pattern of hemolysis (Brown’s Classification) No lysis of RBC’s around colony. No change in agar

Gamma(γ)

Pattern of hemolysis (Brown’s Classification) Small area of intact RBC around colony surrounded by a wider zone of complete hemolysis

Alpha-prime (α’)

Virulence Factor: Streptococcus pyogenes -Antiphagocytic -For adherence to mucosal cells

M Protein

Virulence Factor: Streptococcus pyogenes Mediates adherence to host epithelial cells

Protein F (Fibronectin-binding protein)

Virulence Factor: Streptococcus pyogenes Mediates attachment to mucosal cells

Lipoteichoic acid

Virulence Factor: Streptococcus pyogenes -Prevents opsonized phagocytosis -Mask bacterial antigens

Hyaluronic acid Capsule

Virulence Factor: Streptococcus pyogenes -Group of four enzymes with nuclease activity -Degrade host DNA (DNase) and RNA

Streptodornase (DNases)

Virulence Factor: Streptococcus pyogenes -Subsurface hemolysin (Oxygen labile) -Toxic to RBC’s, WBC’s and platelets -Induces antibody response -anti-streptolysinO

Streptolysin O

Virulence Factor: Streptococcus pyogenes -Surface hemolysin (Oxygen stable) -Lysis WBC’s and is non immunogenic

Streptolysin S

Virulence Factor: Streptococcus pyogenes Causes lysis of fibrin clots

Streptokinase (Fibrinolysin)

Virulence Factor: Streptococcus pyogenes Solubilizes hyaluronic acid in connective tissues

Hyaluronic acid

Virulence Factor: Streptococcus pyogenes Exotoxin A is associated with Scarlet Feverand Streptococcal Toxic shock-like syndrome

Streptococcal pyrogenic exotoxins A, B, C (SPE)

Clinical Infections: Bacterial Pharyngitis and Tonsilitis

streptococcus pyogenes

Clinical Infections: Pyodermal Infections superficial and localized

Impetigo streptococcus pyogenes

Clinical Infections: Pyodermal Infections acute spreading erythematous lesion

Erysipelas Streptococcus pyogenes

Clinical Infections: Pyodermal Infections involves deeper tissue invasion

Cellulitis Streptococcus pyogenes

Clinical Infections: Pyodermal Infections diffuse red rashes (chest to extremities)

Scarlet Fever

Clinical Infections Necrotizing Fasciitis Streptococcal Toxic Shock Syndrome

streptococcus pyogenes

Clinical Infections Post-Streptococcal Sequelae a. Rheumatic Heart b. Acute glomerulonephrits (AGN)

Streptococcus pyogenes

-Capsular material interferes with phagocyticactivity and complement cascade activation. -Transmission occurs vertically or during delivery (associated with obstetric complications) -

-Transmission occurs VERTICALLY or during delivery (associated with obstetric complications) -Causes pneumonia and meningitis

Streptococcus agalactiae

-In adult, causes endometritis and wound infections -Capsular material interferes with phagocytic activity and complement cascade activation.

Streptococcus agalactiae

-Large-colony forming β-hemolytic isolates -Resembles S. pyogenes infections

Groups C and G Streptococci S. dysgalactiae subsp. equisimilis

-small-colony forming β-hemolytic isolates -resembles S. pyogenes infections

Groups C and G Streptococci S. anginosus group

Virulence Factor -Capsular polysaccharide -Antigenic polysaccharide resulting to 80 serogroup -Antiphagocytic -Pneumonia (lobar and community acquired) -Sinusitis, Otitis Media, Bacteremia, Meningitis

streptococcus pneumoniae

Gram-positive diplococci (lancet or bullet shape)

streptococcus pneumoniae

Neufeld reaction (Quellung, capsular swelling) positive

streptococcus pneumoniae

Associated Disease 1. SUBACUTE BACTERIAL ENDOCARDITIS from patients with damaged heart valves. 2. Bacteremia, septicemia and cavities

Viridans Streptococci (A,C,F, G,N)

Associated Disease 1. Nosocomial infection 2. UTI (catheterization), bacteremia (hemodialysis, surgery), endocarditis (prosthetic heart valves)

Enterococcus

Streptococci Disease Associations Pharyngitis, PYODERMAL infections, NECROTIZING FASCIITIS, STREPTOCOCCAL TOXIC SHOCK SYNDROME, POST SEPSIS SYNDROME (Rheumatic fever, AGN)

S. pyogenes

Streptococci Disease Associations NEONATAL SEPSIS (pneumonia, meningitis) PUERPERAL fever, pyogenic infections

S. agalactiae

Streptococci Disease Associations Pharyngitis, IMPETIGO, pyogenic infections

S. dysgalactiae, S. equi

Streptococci Disease Associations UTI, endocarditis, pyogenic infections, BACTEREMIA

E. faecalis, E. faecium

Streptococci Disease Associations PNEUMONIA, MENINGITIS, pyogenic infections

S. pneumoniae

Streptococci Disease Associations Pyogenic infections, endocarditis, DENTAL CARIES

Anginosus, mutans, mitis

Colony Characteristics Grayish white (pinpoint), transparent to translucent, matte or glossy; large zone of βhemolysis

Group A strep

Colony Characteristics Larger that Group A streptococci; translucent to opaque; flat glossy; narrow zone of β hemolysis

Group B strep

Colony Characteristics Minute to small, gray, domed, smooth; α, β,γ hemolytic

Viridans

Colony Characteristics Small, cream or white, smooth; α, β,γ hemolytic

Group D strep

Colony Characteristics Small, round, glistening, dome-shaped, mucoid colonies. Colonies tend umbilicated as they age; α hemolytic

Pneumococci

Physiologic Characteristics Produce pus, mostly β-hemolytic

Pyogenic

Physiologic Characteristics Nonhemolyticorganism with lancefield group N, often found in dairy products

Lactococci

Physiologic Characteristics Normal biota of the human intestine

Enterococci

Physiologic Characteristics Found as normal biota in the upper respiratory tract of humans

Viridans

Culture Media for Streptococcus Enriched isolation of Streptococci

Blood Agar

Culture Media for Streptococcus Selective medium for Beta-hemolytic Streptococci

Blood Agar with trimethoprim and sulfamethoxazole

Taxo A susceptible and SXT Resistant

Group A

Taxo A resistant and SXT resistant

Group B:

Taxo A resistant and SXT susceptible

Group C, F, G

Test for the synergistic hemolysis between group B Streptococcus and β-hemolytic S. aureus.

CAMP Reaction

is a diffusible, proteinlike compound produced by Group B

CAMP factor

CAMP Reaction Positive: Enhanced hemolysis in arrowhead pattern Strep group ?

group B

Test for the ability to hydrolyze hippuric acid (Sodium hippurate ) to benzoic acid and glycine

Hippurate Hydrolysis

Glycine can be detected with Ninhydrin reagent

Hippurate Hydrolysis

Hippurate Hydrolysis Positive: Deep blue (purple) color group ?

group B

Hippurate Hydrolysis Negative: Colorless or very slight purple group ?

group A

Detects for the ability of the bacteria to hydrolyze Leucine-β-naphthylamide by enzyme leucine aminopeptidase to β-naphthylamide.

LAP Test

Positive: Development of a red color within 1 minute after adding cinnamaldehyde (DMACA) reagent

LAP Test

LAP Test S. Pneumoniae and S. pyogenes, Enterococcus, Pediococcus

LAP Test Aerococcus and Leuconostoc

Detects for the ability of the bacteria to grow in the presence of 40% bile and hydrolyze esculin.

Bile Esculin Hydrolysis

Positive: Blackening of the agar

Bile Esculin Hydrolysis

Bile Esculin Hydrolysis Group D Streptococcus

Bile Esculin Hydrolysis Viridans Streptococcus

Test the ability of the organism to grow in 6.5% NaCl

salt Tolerance Test (6.5% NaCl)

Positive: Visible turbidity in broth and color change

salt Tolerance Test (6.5% NaCl)

salt Tolerance Test (6.5% NaCl) (Group D Enterococcus)

salt Tolerance Test (6.5% NaCl) (Group D Non Enterococcus)

-Used to differentiate Streptococcus pneumoniae from other α-hemolytic streptococci -Ethylhydrocupreine hydrochloride

Optochin (Taxo P) Susceptibility

Optochin (Taxo P) Susceptibility Positive: Zone of inhibition is >14mm (using 6 mm P disk) or >16mm (using a 10 mm P disk)

S. pneumoniae

Test for the solubility to bile salt (2% sodium deoxycholate or sodium taurocholate)

Bile Solubility Test

Positive: Colony disintegrates

Bile Solubility Test

alpha hemolytic optochin resistant bile esculin hydrolysis + =GROUP D PYR or 6.5% broth +

enterococcus

alpha hemolytic optochin resistant bile esculin hydrolysis + =GROUP D PYR or 6.5% broth

non enterococcus

alpha hemolytic optochin SUSCEPTIBLE bile esc, pyr, 6.5%-

s. pneumoniae

alpha hemolytic optochin RESISTANT bile esc, pyr, 6.5%-

s. viridans

all streptococci are bacitracin RESISTANT except

group A

all streptococci are SXT RESISTANT except

group C,F,G viridans

betahemolytic Group ? Bacitracin: S SXT: R CAMP: - Bile-Esculin: - 6.5% NaCl: - PYR: +

betahemolytic Group ? Bacitracin: R SXT: R CAMP: + Bile-Esculin: - 6.5% NaCl: - PYR: -

betahemolytic Group ? Bacitracin: R SXT: S CAMP: - Bile-Esculin: - 6.5% NaCl: - PYR: -

C, F, G viridans

betahemolytic Group ? Bacitracin: R SXT: R CAMP: - Bile-Esculin: + 6.5% NaCl: - PYR: -

D streptococcus

betahemolytic Group ? Bacitracin: S SXT: R CAMP: - Bile-Esculin: + 6.5% NaCl: + PYR: +

D enterococcus

gamma hemolytic group ? bile esculin: - 6.5% salt broth: - PYR: -

viridans

gamma hemolytic group ? bile esculin: + 6.5% salt broth: + PYR: +

D enterococcus

gamma hemolytic group ? bile esculin: + 6.5% salt broth: - PYR: -

D non enterococcus

SEMR: Gram (+) cocci Flashcards

(181 cards)