Aerobic and Facultatively Anaerobic Gram-Positive Cocci 4.38/5 (13)

Aerobic and Facultatively Anaerobic Gram-Positive Cocci

Enterococcus faecalis and Enterococcus faecium

Clinical Features

Urinary tract infections, peritonitis, bacteremia, endocarditis

Virulence Factors

Relatively avirulent

Aerobic and Facultatively Anaerobic Gram-Positive Cocci


Staphylococcus aureus

Clinical Features

Suppurative infections: impetigo, folliculitis, furuncles, carbuncles, wounds

Disseminated infections: bacteremia, endocarditis, pneumonia, empyema, osteomyelitis, septic arthritis

Toxin-mediated infections: toxic shock syndrome, scalded skin syndrome, food poisoning

Virulence Factors

Possess thick peptidoglycan layer, capsule, protein A, various toxins (cytotoxins, exfoliative toxins, enterotoxins, toxic shock syndrome toxin, Panton- Valentine leukocidin) and hydrolytic enzymes

Staphylococcus, coagulase-negative

Clinical Features

Wound infections, urinary tract infections, catheter and shunt infections, prosthetic device infections

Virulence Factors

Possess thick peptidoglycan layer and loose polysaccharide slime layer; Staphylococcus saprophyticus
produces high concentrations of urease

Streptococcus pyogenes (group A)

Clinical Features

Suppurative infections: pharyngitis, scarlet fever, sinusitis, skin and softtissue infection (impetigo,
erysipelas, cellulitis, necrotizing fasciitis), toxic shock–like syndrome; bacteremia

Nonsuppurative infections: rheumatic fever, glomerulonephritis

Virulence Factors

Capsule, M protein, M-like protein, F protein, pyrogenic exotoxins, streptolysin S and O, streptokinase,
deoxyribonuclease, C5a peptidase

Streptococcus agalactiae (group B)

Clinical Features

Neonatal disease (early onset, late onset): bacteremia, pneumonia, meningitis; postpartum endometritis, wound infection, skin and soft-tissue infection, urinary tract infections, pneumonia

Virulence Factors

Similar to group A but no capsule

Viridans streptococci

Clinical Features

Abscess formation; septicemia in neutropenic patients; subacute endocarditis; odontogenic infections; dental caries

Virulence Factors

Relatively avirulent

Streptococcus pneumoniae

Clinical Features

Pneumonia, sinusitis, otitis media, meningitis, bacteremia, endocarditis, spontaneous bacterial peritonitis, septic arthritis

Virulence Factors

Polysaccharide capsule; teichoic acid; immunoglobulin A protease; pneumolysin O

Aerobic and Facultatively Anaerobic Gram-Positive Cocci

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