Gram+ bacteria

Staphylococcus aureus — infections & key traits

• gram pos

• Skin/wound infections, sepsis, endocarditis;

• coagulase+, toxins (superantigen/exfoliative), biofilm;

• treat with oxacillin or 1st/2nd gen cephalosporin.

Staphylococcus epidermidis — infection & key trait

• gram pos

• Intravascular catheters/prosthesis infections;

• biofilm formation;

• coagulase−;

• treat with vancomycin.

Streptococcus pyogenes — diseases & virulence

• gram pos

• Tonsillitis, scarlet fever, erysipelas; M protein, streptolysin, superantigen; treat with penicillin G.

Streptococcus pneumoniae — infection & features

• gram pos

• Pneumonia, meningitis, otitis media; capsule, sputum diplococci; treat with penicillin G (or cephalosporin if resistant).

Clostridium difficile — infection & key trait

• gram pos

• Pseudomembranous colitis after antibiotics; toxin A/B, spores; treat with oral vancomycin or metronidazole.

Clostridium tetani — disease & mechanism

• gram pos

• Tetanus with muscle spasms/lockjaw; neurotoxin blocks inhibitory neurotransmitters; treat with tetanus immunoglobulin + benzodiazepines.

Clostridium perfringens — disease & toxin

• gram pos

• Gas gangrene, food poisoning; alpha toxin, spores; treat surgically + penicillin.

Listeria monocytogenes — infection & features

• gram pos

• Meningitis in neonates/pregnant; intracellular, actin rockets; treat with ampicillin.

Mycobacterium tuberculosis — disease & key trait

• gram pos

• Tuberculosis (cough, fever, night sweats); intracellular survival in macrophages; treat with isoniazid + rifampicin + ethambutol + pyrazinamide.