Staphylococcus Flashcards by Kyra Catedral

• ^ peptidoglycan; + v level of lipid (cell wall)

Gram Positive Cocci

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Gram + cocci

Lead to accumulation of neutrophils, bacterial cells, and fluids at the site
> ___________

Pyogenic infection

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All gram positive cocci (14)

Staphylococcus
1. Streptococcus
2. Stomatococcus
3. Salinicoccus
4. Leuconostoc
5. Lactococcus
6. Aerococcus
7. Alloiococcus
8. Planococcus
9. Pediococcus
10. Micrococcus
11. Macrococcus
12. Gemella
13. Rothia

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Reclassification of Gram Positive Cocci
• In 1996:

Bergey’s Manual of Systematic Bacteriology

• Family Micrococcaceae includes 4 genera:
• Micrococcus
• Planococcus
• Staphylococcus
• Stomatococcus

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In 1996: Bergey’s Manual of Systematic Bacteriology
• Family Micrococcaceae includes 4 genera:

• Micrococcus
• Planococcus
• Staphylococcus
• Stomatococcus

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• Ribosomal RNA & DNA Hybridization Analysis
• Recent Edition:
• 2 families:

• Family Staphylococcaceae
• Family Micrococcoceae

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Family Staphylococcaceae
• Includes :

• Genus Gemella
• Genus Staphylococcus
• Genus Salinicoccus
• Genus Macrococcus

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Family Micrococcaceae
• Includes:

• Genus Micrococcus
• Genus Arthrobacteria
• Genus Kocuria

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Stomatococcus mucilaginosus
• Only member of the Genus Stomatococcus
• Reclassified under the Genus Rothia
_____________

Rothia mucilaginosus

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Mucilanigosus

• [can/cannot] grow in the presence of 5% NaCl

• Weakly_____ (+),______ (-) and has a_____

• Emerging pathogen in______

Cannot

catalase, coagulase; capsule

immunosuppressed patients

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M vs S

Bacitracin (0.04 unit)

Micrococcus
Staphylococcus

Susceptible
Resistant

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M vs S

Furazolidone (100 ug/mL)

Micrococcus
Staphylococcus

Resistant
Susceptible

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M vs S

Lysostaphin (200 ug/mL)

Micrococcus
Staphylococcus

Resistant
Susceptible

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M vs S

Carbohydrate Utilization (OF Medium)

Oxidative
Fermentative

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M vs S

Modified Oxidase (Microdase) test

Micrococcus
Staphylococcus

Positive
Negative

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M vs S

Growth on Furoxone-Tween 80-oil red 0 agar

Micrococcus
Staphylococcus

Positive
Negative

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Staphylococcus
Significant human species: SHHEAW

S. saprophyticus
1. S. hominis
2. S. hemolyticus
3. S. epidermidis
4. S. aureus
5. S. warneri

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Staphylococcus: General Characteristics
Clinically Significant:

• S. aureus
• S. epidermidis
• S. saprophyticus

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Staphylococcus

• Catalase____
• G (+) соссі
• motile? Spore forming?
• O2 requirement???
• Modified oxidase___
• Reduces___ to ____
• Grows in ____ to ____NaCl
• Lysostaphin____
• Bacitracin____

(+)

Nonmotile & Non-spore forming

Facultative anaerobes

(-)

nitrates to nitrites

7.5% to 10%

sensitive

resistant

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Staphylococcus

• Transmission:

• Infections:

Direct contact
Fomites
poor hygiene

virulence of strain
size of inoculum
Immune status

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Staphylococcus aureus
VIRULENCE FACTORS

• Surface structures
• Enzymes
• Toxins

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Staphylococcus aureus
SURFACE STRUCTURES

Protein A
Capsular polysaccharide
Peptidoglycan & Teichoic acid*

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SAU Enzymes

Enzymes
• Catalase
• Bound coagulase
• Staphylokinase
• Lipase
• Hyaluronidase
• DNase
• Beta lactamase

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SAU toxins

Toxins
• Exfoliatin
• Leukocidin
• Hemolysins
• Enterotoxins
• Superantigens

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Staphylococcus aureus SURFACE STRUCTURES • binds to Fc region of IgG • affects the immediate & delayed hypersensitivity reactions

Protein A

SAU surface structure • Anti-phagocytic •Enhance binding to host cells & prosthetics protein A antibody.

Capsular polysaccharide

SAU • Chemoattractant for neutrophils; Activates complement • Elicits production of IL-1 & opsonic Abs by monocytes • mediates adhesion by binding to tissue fibronectin*

Peptidoglycan & Teichoic acid*

Staphylococcus aureus DISEASE PROCESS

• SAU → invades tissues & produce toxins • Organism spread (site of carriage) → site of infection (breaks on the skin) • Organism → blood → lungs, bones, liver, brain, or heart

Staphylococcus aureus DISEASES Types of Staphylococcal Diseases:

• Local Abscesses • Focal Suppuration • Diseases caused by toxin elaboration

SAU LOCAL ABSCESSES

• Folliculitis • Furuncles (Boils) • Carbuncles • Sty

SAU FOCAL SUPPURATION

• Osteomyelitis • Pneumonia • Meningitis • Empyema • Endocarditis • Sepsis • Impetigo / Pyoderma

EXOTOXIN ELABORATION • Enterotoxins A & B Nausea, vomiting & abdominal pain

• FOOD POISONING

EXOTOXIN ELABORATION • Enterotoxins A & B Nausea, vomiting & abdominal pain

• FOOD POISONING

EXOTOXIN ELABORATION Epidermolytic toxin/ exfoliatin = Exfoliation

• SCALDED SKIN SYNDROME

EXOTOXIN ELABORATION • multisystemic disease • TSST-1 producing strains of SAU

• TOXIC SHOCK SYNDROME

GENERAL CHARACTERISTICS • Normal flora of skin & mucous membranes • G (+) cocci in clusters

Staphylococcus epidermidis

Staphylococcus epidermidis GENERAL CHARACTERISTICS • Virulence factor

• Biofilm production • cell surface & extracellular compounds • promote adherence of bacteria to surfaces of prosthetic devices.

Staphylococcus epidermidis •______ growth on BAP •____ growth on CNA • _______on MSA • Coagulase___ • DNase___ •____ to Novobiocin

White creamy non-hemolytic + Can grow but lacks fermentation (-) Susceptible (-)

Staphylococcus epidermidis DISEASES catheters prosthetic heart valve implantation prosthetic devices: CNS shunts, intravascular catheters vimmunosuppression

HOSPITAL ACQUIRED

GENERAL CHARACTERISTICS • Contaminant • important cause of UTI among sexually active females • Catheter-associated UTI

Staphylococcus saprophyticus

Staphylococcus saprophyticus • Catalase___ • Coagulase___ • DNase___ • ___on BAP • MSA____ •____ to 5 ug NOVOBIOCIN

(+) (-) (-) Non-hemolytic fermentation variable Resistant

• Strains of SAU that are resistant to beta lactams

Methicillin Resistant Staphylococcus aureus (MRSA)

• Many SAU strains produce______ and are _____

B-lactamase & are penicillin-resistant

• Significant nosocomial infection (HA-MRSA) • CA-MRSA

Methicillin Resistant Staphylococcus aureus (MRSA)

Methicillin Resistant Staphylococcus aureus (MRSA) Antibiotics

Oxacillin, cloxacillin & methicillin

Staphylococcus Specimen Collection & Processing Specimens: + NOTED

• Wound • Blood • Sputum • Urine • Do direct gram stain from specimen • Gram (+) cocci & neutrophils are noted

Staphylococcus: Culture Medium

Sheep's Blood Agar Plate Colistin Nalidixic Acid Agar (CNA) Growth on MSA Chromogenic Agar (Hardy Chrome Staph aureus agar)

• Medium, convex, creamy, dome shaped • Pigment: white to golden yellow

Sheep's Blood Agar Plate

• Selective medium for growth of G(+) bacteria • The medium is blood agar base with Antibiotics

Colistin Nalidixic Acid Agar (CNA)

• Selective & differential medium • 1 salt (7.5%) = selective • Mannitol & phenol red

Growth on MSA

Chromogenic Agar (Hardy Chrome Staph aureus agar) ______ appears deep pink to fuchsia colonies ______partially or completely inhibited ______appears turquoise colonies

• SAU • S. epidermidis • S. saprophyticus

Staphylococcus aureus MACROSCOPIC CHARACTERISTICS COLONIES

• Medium to large smooth, butyrous, creamy • Margin is entire • Staphyloxanthin (yellow pigment) • Narrow zone of B-hemolysis (SBA

Test for Differentiation: Catalase Test

• Differentiate Staphylococcus from Streptococcus

Test for Differentiation: Coagulase Test

• Differentiate Staphylococcus aureus from CoNS

• Latex agglutination • Latex particle (coated with human plasma fibrinogen & IgG) → reacts with clumping factor & protein A of SAU

Rapid Detection of Coagulase Activity

Ex. BBL Staphyloslide Latex Test • _____________→ cross-linking → agglutination w/ latex particle

Blue Latex reagent + SAU colonies

Test for Differentiation: Modified Oxidase Test

• Differentiate Micrococcus from Staphylococcus

Modified oxidase test reagent

Reagent: • 6% tetramethyl-p-phenylenediamine dihydrochloride in dimethyl sulfoxide

Modified Oxidase Test Result: • (+) = • (-) =

dark blue - purple color (Cytochrome C) no change in color

Test for Differentiation: Bacitracin Susceptibility Test • Differentiate_______ _____ and ______

Micrococcus & Rothia from Staphylococcus

Test for Differentiation: Bacitracin Susceptibility Test • Differentiate _____ and _____ to _____ •____ u Bacitracin disk • Interpretation: •_____ = Susceptible • _____= Resistant

Micrococcus & Rothia from Staphylococcus 0.04 Zones > 10 mm Zones < 10 mm or no zone of inhibition

Test for Differentiation: Bacitracin____ • Differentiate Micrococcus & Rothia from Staphylococcus • 0.04 u Bacitracin disk • Interpretation: • Zones > 10 mm = Susceptible • Zones < 10 mm or no zone of inhibition = Resistant

Susceptibility Test

Test for Differentiation: Bacitracin Susceptibility Test Micrococcus & Rothia : Staphylococcus :

S R

MOT Result: (Cytochrome C)

• (+) = dark blue - purple color

Test for Differentiation: Novobiocin Susceptibility Test

• Differentiate S. saprophyticus from other CoNS

Test for Differentiation: Novobiocin Susceptibility Test • S. saprophyticus:_____ • other CoNS :_____ • Place____ of Novobiocin

Resistant Sensitive 5ug

Novobiocin Susceptibility Test Interpretation:

• Susceptible = zone > than 16 mm • Resistant = zone < or = to 16 mm

Test for Differentiation: • For the presumptive identification of S. aureus and differentiates it from CoNS. • Methyl Green: • Toluidine Blue O: • Detection of thermostable nuclease

DNAse Test colorless bright pink color.

Detection of Antibiotic Resistant SAU MRSA

1. Cefoxitin Disk Screen Test 2. Latex agglutination for PBP2a 3. MH agar with NaCl & 6 ug/mL of Oxacillin 4. Chromogenic Agar 5. Detection of mecA gene or its product PBP2a

Treatment and Prevention • Handwashing; local antisepsis • Drainage of pus • Surgical drainage, removal of tissue

-For S. aureus:

SAU Antimicrobial Therapy:

• Methicillin, nafcillin, cloxacillin • Vancomycin • Tetracyclines

For • Difficult to treat. Removal of the prosthetics may be done. • 40% of CoNS are resistant to B-lactamase resistant antibiotics

S. epidermidis:

S. epidermidis: • Treatment:

• Penicillin G • semisynthetic penicillinase-resistant penicillins • cephalosporins • Vancomycin

• The majority of _______infections can be adequately treated with antibiotics. • Untreated → progress to pyelonephritis.

S. saprophyticus

S. saprophyticus • The antibiotic of choice: v Nitrofurantoin (Macrobid) ~ Trimethoprim-sulfamethoxazole (TMP-SMX)

• The antibiotic of choice: v Nitrofurantoin (Macrobid) ~ Trimethoprim-sulfamethoxazole (TMP-SMX)

will break down Hydrogen peroxide into water and oxygen (Bubble formation) ***Hydrogen peroxide*** is needed by the immune cells to function properly - no H202 means no immune action - no opsonization,

Catalase

will convert Fibrinogen into Fibrin which will result in a clot. A clot in the body is toxic to the immune cells

Coagulase

Clotting factor

Bound Coagulase

TWO TYPES OF COAGULASE (Clotting Factor) (Tube Coagulase)

1. Bound coagulase 2. Free coagulase

Enzyme that dissolves the clot. The clot becomes small particles - these STILL become toxic for the immune cells Spreads infection throughout the body

Staphylokinase

Hydrolyze lipids in the skin / if ever the lipids have been hydrolyzed, this manifests SKIN INFECTIONS caused by the Staphylococcus boils, carbuncles, furuncles

Lipase

Hydrolyzes hyaluronic acid - it is responsible for the spread infection

Hyaluronidase

Also known as Penicillinase Breaks down B-lactam rings in which these are found in antibiotics, specifically in penicillin making penicillin ineffective for Staphylococcus aureus

Beta lactamase

Cleave stratum granulosum of the skin Excessive peeling of skin Associated with Staphylococcal Scalded Skin Syndrome

Exfoliatin

Toxin responsible for continuously puncturing holes in the immune cells rendering them dead and inhibit phagocytosis

Leukocidin

Toxin responsible for continuously puncturing holes in the immune cells rendering them dead and inhibit phagocytosis

Hemolysins

Among the seven heat stable, only two are very common that can cause food poisoning → ***A and B***

Enterotoxins

Responsible for making cytokines in the body - too much cytokines will let them accumulate, and increased cytokines will cause havoc

Superantigens

→ Inflammation of hair follicles - where it is supposed to grow → Back, arms, buttocks

Folliculitis

→ Presence of pus → a.k.a Abscess

Furuncles (Boils)

→ Collection of boils left untreated → Common at the region of the nape

Carbuncles

→ Skin is affected, then the bone is inflamed next → Left untreated, will require amputation → Common in patients with diabetes

Osteomyelitis

→ Presence of pus in the lungs

Empyema

→ Common in toddlers/infants that are yet to develop immunity

Impetigo/ Pyoderma

• Medium-large in size, convex, creamy, dome shaped Beta-hemolytic, some Staphylococcus spp. have no hemolysis Pigment: white to golden yellow

Sheep's Blood Agar Plate

Selective medium for growth of G(+) bacteria The medium is blood agar base with Antibiotics

Columbia Colistin Nalidixic Acid Agar (CNA)

Selective & differential medium 1 salt (7.5%) = selective Mannitol and phenol red

Growth on MSA

Staphylococcus Flashcards

(97 cards)