SEMR: Gram (+) cocci Flashcards
peptidoglycan layer:
gram +=
gram -= single layered
multilayered
peptidoglycan layer:
gram += multilayered
gram -=
single layered
teichoic acids:
gram +=
gram -= absent
present in many
teichoic acids:
gram += present in many
gram -=
absent
GRAM +
peptidoglycan layer:
teichoic acids:
periplasmic space:
outer membrane:
LPS content:
lipid and lipoprotein:
multilayered
present in many
absent
absent
none
low
GRAM -
peptidoglycan layer:
teichoic acids:
periplasmic space:
outer membrane:
LPS content:
lipid and lipoprotein:
single layered
absent
present
present
high
high
gram +
catalase +
2 families
- micrococcaceae
- staphylococcaceae
gram +
catalase -
2 families
- streptococcaceae
- enterococcus
determinant in development of staphylococcal infections (3)
- virulence
- size of inoculum
- status of host’s immune system
Gram (+) cocci arranged in tetrads or clusters
Facultative anaerobes
Catalase positive
Oxidase Negative
Non-motile
Grows in 7.5-10% NaCl
Staphylococci
only Staphylococci that is obligate anaerobe
s. saccharolyticus
Test the ability of the organism to breakdown of H2O2(3%) into oxygen and water.
Catalase Test
result of test: Copious bubble formation
catalase test
-Most clinically significant specie of Staphylococci
-Present in various skin surfaces
-Cause of nosocomial or hospital-acquired infections
Staphylococcus aureus
Virulence Factor: S. aureus
Enterotoxins that are associated to food poisoning
(diarhea, vomiting); reheating contaminated food
will not prevent disease
A, B, D
Virulence Factor: S. aureus
heat stable exotoxins: include
A-E
G-J
Virulence Factor: S. aureus
Formerly known as Enterotoxin F (superantigen-activate aggressive immune response)
TSST-1
Virulence Factor: S. aureus
Causes menstruating-associated TSS (Tampon use)
absorbed through vaginal mucosa
TSST-1
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
large pustules with erythema
bullous impetigo
Virulence Factor: S. aureus
Cytolytic Toxins
Destruction of neutrophils and macrophages
Panton-Valentine Leukocidin(γ-Hemolysin)
Virulence Factor: S. aureus
Cytolytic Toxins
Lyse erythrocytes
Hemolysins (α, β, δ)
Virulence Factor: S. aureus
Enzymes
Conversion of fibrinogen to fibrin
Bound Coagulase & Free Coagulase
Coagulase (Staphylocoagulase)
Virulence Factor: S. aureus
Enzymes
Dissolve fibrin clots and may enable spread of
infection.
Fibrinolysin (Staphylokinase)
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: +
A
betahemolytic
Group ?
Bacitracin: R
SXT: R
CAMP: +
Bile-Esculin: -
6.5% NaCl: -
PYR: -
B
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
