Which of the following is gram-positive bacillus-

Listeria is gram-positive bacillus. Staphylococcus and streptococcus are also gram-positive, but they are cocci (not bacilli). Meningococci are gram-negative cocci. Also know Clinically important spore-forming bacteria are gram-positive → Clostridium, Bacillus. Listeria is the only gram-positive bacteria that has endotoxin. (Endotoxin is present only in gram-negative organisms). Of the gram-negative organisms, only two groups are cocci - Neisseria (meningococcus & gonococcus), veillonella. All other gram-negative organisms are bacilli (including coccobacilli). Amongst medically important bacilli '6' are gram (+)ve → Actinomycetes, clostridium, mycobacteria, Bacillus, Listeria, Corynebacterium. All other medically important bacilli are gram-negative.