Micrococcaceae

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Micrococcaceae

• Student Lab
• Division of Laboratory Sciences
• Michele Jurgensmeier MT(ASCP)

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General Information
Gram Positive Cocci

• Cause human infections
• Recover from various clinical specimens
• Found in many places
• Spread by direct contact
• Elaborate an inflammatory response
• Produce pathogenic effects

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Family Micrococcaceae
Gram Stain Gram positive cocci
Catalase Positive
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Gram Stain
Micrococcus species

• Gram Positive Cocci in tetrads

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Growth Characteristics
Micrococcus species

• Aerobic
• Colony morphology
• Smooth, raised, opaque
• Pigment

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Biochemical Characteristics
Micrococcus species

• Non-motile
• Non-spore forming
• Glucose oxidizer
• Modified oxidase
• Bacitracin sensitive
• Furazolidine Resistant
• Lysostaphin Resistant

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Micrococcus species

• Bacitracin Sensitive
• Zone size gt 10 mm around disk

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Micrococcus species

• Glucose Oxidizer
• Tube on left shows glucose oxidation by the
  presence of yellow color (No oil overlay)
• Tube on right shows no fermentation of glucose
  (oil overlay)

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Clinical Significance
Micrococcus species

• Rarely produces disease
• Normal flora
• Opportunistic infection
• Immunocompromised

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Antibiotic Therapy
Micrococcus species

• Test methods and therapeutic guidelines do not
  exist
• Susceptible to beta-lactam antimicrobics

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Gram Stain
Staphylococcus species

• Gram Positive Cocci in clusters

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Growth Characteristics
Staphylococcus species

• Facultative anaerobes

• Colony morphology

• Opaque, smooth, circular
• Gray-white, white, cream, yellow
• Hemolysis
• S. aureusbeta-hemolytic

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Biochemical Characteristics
Staphylococcus species

• Non-motile
• Non-spore forming
• Glucose fermenter
• Modified oxidase -
• Bacitracin resistant
• Furazolidine sensitive
• Most are sensitive to Lysostaphin
• Variable growth in 6.5 Salt (Salt tolerance)

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Micrococcus Staphylococcus species
species

• Gram positive cocci
• Catalase Positive
• Bacitracin Sens.
• Mod. Oxidase Pos
• Glucose Oxidizer

• Gram Positive cocci
• Catalase Positive
• Bacitracin Sens.
• Mod. Oxidase Neg
• Glucose Fermenter

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Colony morphology
Staphylococcus aureus

• Opaque, smooth
• Raised colony with smooth border
• White-gold (cream) in color
• Beta hemolytic

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Biochemical Characteristics
Staphylococcus aureus

• Coagulase

• Mannitol salt

• DNase

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Mechanisms of Pathogenicity
Staphylococcus aureus

• Capsule
• Enzymes
• Catalase
• Coagulase
• Staphylokinase
• Hyaluronidase
• DNase
• Beta-lactamase

• Toxins
• Hemolysin
• Leukocidin
• Exfoliatin
• Enterotoxin
• TSST-1

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Clinical Significance
Staphylococcus aureus
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Impetigo
Scalded Skin Syndrome
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Antibiotic Therapy
Staphylococcus aureus

• Penicillinase (beta-lactamase)
• Agents resistant to penicillinase
• Methicillin
• Oxacillin
• Nafcillin
• Methicillin Resistant Staph aureus
• Drug of choice - vancomycin

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Methicillin Resistant S. aureus
Staphylococcus aureus

• S R strains coexist
• R strains grow more slowly
• Growth requirements
• Media with neutral pH
• Cooler temperature (30-35 C)
• 2-4 NaCl
• Incubate full 24 hours

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Clinical Significance
Coagulase Negative Staphylococcus
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Colony morphology
Staphylococcus epidermidis

• Opaque
• Smooth, raised

• Gray- white in color

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Biochemical Characteristics
Staphylococcus epidermidis

• Coagulase -

• Mannitol salt -

• DNase

• Novobiocin S

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Mechanisms of Pathogenicity
Staphylococcus epidermidis

• Capsule
• Extracellular slime substance

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Clinical Significance
Staphylococcus epidermidis

• Normal flora
• Subacute bacterial endocarditis
• Meningitis
• Bacteremia / Septicemia
• Wound infections
• Urinary tract infections
• Post-operative infections

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Antibiotic Therapy
Staphylococcus epidermidis

• More resistant than Staph aureus
• Susceptibility testing done if presumed pathogen
• Drugs of choice
• Methicillin
• Vancomycin (if methicillin R)

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Biochemical Characteristics
Staphylococcus saprophyticus

• Coagulase -

• Mannitol salt variable

• DNase

• Novobiocin R (lt16 mm)

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Clinical Significance
Staphylococcus saprophyticus

• Urinary tract infections
• Cystitis in young women
• Frequency - 2nd to E. coli

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Antibiotic Therapy
Staphylococcus saprophyticus

• Susceptibility testing not routinely done
• Drugs of choice
• Nitrofurantoin
• Trimethoprim/sulfamethoxizole
• Fluoroquinolone
• Lack correlation between in vitro and in vivo
  response

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GPC - Catalase Positive
Micrococcaceae
Modified oxidase Bacitracin OF Glucose
Positive Sensitive Oxidizer
Negative Resistant Fermenter
Coagulase -
Micrococcus species
Staph aureus
R Novobiocin S
Coag neg Staph
ProbableStaph sapro