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

General Information Cause human infections Recover from various clinical specimens Found in many places Spread by direct contact Elaborate an inflammatory response Produce pathogenic effects Gram Positive Cocci

Family Micrococcaceae Gram Stain: Gram positive cocci Catalase: Positive

Gram Stain Gram Positive Cocci in tetrads Micrococcus species

Growth Characteristics Aerobic Colony morphology –Smooth, raised, opaque –Pigment Micrococcus species

Biochemical Characteristics Non-motile Non-spore forming Glucose oxidizer Modified oxidase + Bacitracin sensitive Furazolidine Resistant Lysostaphin Resistant Micrococcus species

Bacitracin Sensitive Zone size > 10 mm around disk 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) Micrococcus species

Clinical Significance Rarely produces disease Normal flora Opportunistic infection –Immunocompromised Micrococcus species

Antibiotic Therapy Test methods and therapeutic guidelines do not exist Susceptible to beta-lactam antimicrobics Micrococcus species

Gram Stain Gram Positive Cocci in clusters Staphylococcus species

Growth Characteristics Facultative anaerobes Staphylococcus species Colony morphology –Opaque, smooth, circular –Gray-white, white, cream, yellow –Hemolysis S. aureus beta-hemolytic

Biochemical Characteristics 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) Staphylococcus species

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

Colony morphology Opaque, smooth Raised colony with smooth border White-gold (cream) in color Beta hemolytic Staphylococcus aureus

Biochemical Characteristics Coagulase + Staphylococcus aureus Mannitol salt + DNase +

Mechanisms of Pathogenicity Capsule Enzymes –Catalase –Coagulase –Staphylokinase –Hyaluronidase –DNase –Beta-lactamase Toxins –Hemolysin –Leukocidin –Exfoliatin –Enterotoxin TSST-1 Staphylococcus aureus

Clinical Significance Staphylococcus aureus

Impetigo Scalded Skin Syndrome

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

Methicillin Resistant S. 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 Staphylococcus aureus

Clinical Significance Coagulase Negative Staphylococcus

Colony morphology Opaque Smooth, raised Staphylococcus epidermidis Gray- white in color

Biochemical Characteristics Coagulase - Staphylococcus epidermidis Mannitol salt - DNase – Novobiocin “S”

Mechanisms of Pathogenicity Staphylococcus epidermidis Capsule Extracellular slime substance

Clinical Significance Normal flora Subacute bacterial endocarditis Meningitis Bacteremia / Septicemia Wound infections Urinary tract infections Post-operative infections Staphylococcus epidermidis

Antibiotic Therapy More resistant than Staph aureus Susceptibility testing done if presumed pathogen Drugs of choice –Methicillin –Vancomycin (if methicillin “R”) Staphylococcus epidermidis

Biochemical Characteristics Coagulase - Staphylococcus saprophyticus Mannitol salt variable DNase – Novobiocin “R” (<16 mm)

Clinical Significance Urinary tract infections –Cystitis in young women –Frequency - 2 nd to E. coli Staphylococcus saprophyticus

Antibiotic Therapy Susceptibility testing not routinely done Drugs of choice –Nitrofurantoin –Trimethoprim/sulfamethoxizole –Fluoroquinolone Lack correlation between in vitro and in vivo response Staphylococcus saprophyticus

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