MORPHOLOGY

Cocci arranged in clusters

Staphylococci

Cocci arranged in chains

Streptococci

Cocci arranged in pairs

Diplococci

A Gram-positive coccus that appears in grape-like clusters

Staphylococcus

A Gram-positive coccus that appears in chains

Streptococcus

A Gram-negative diplococcus that causes meningitis

Neisseria meningitidis

A Gram-negative diplococcus that causes gonorrhea

Neisseria gonorrhoeae

A Gram-positive coccus that is catalase-positive and associated with skin infections

Staphylococcus aureus

A Gram-positive coccus that is catalase-negative and involved in respiratory tract infections

Streptococcus pneumoniae

A Gram-positive coccus that is part of normal gut flora and can cause opportunistic infections

Enterococcus

A Gram-negative diplococcus that requires increased CO₂ for optimal growth

Neisseria species

A Gram-positive bacillus that forms endospores and causes anthrax

Bacillus anthracis

A Gram-positive bacillus that forms endospores and is associated with food poisoning

Bacillus cereus

A Gram-positive, spore-forming bacillus that causes tetanus

Clostridium tetani

A Gram-positive, spore-forming bacillus that causes botulism

Clostridium botulinum

A Gram-positive, spore-forming bacillus that causes gas gangrene

Clostridium perfringens

A Gram-positive, non-spore-forming bacillus that can cause meningitis in neonates

Listeria monocytogenes

A Gram-positive, acid-fast bacillus that causes tuberculosis

Mycobacterium tuberculosis

A Gram-positive, acid-fast bacillus that causes leprosy

Mycobacterium leprae

A Gram-negative bacillus that is a major cause of foodborne illness and gastroenteritis

Salmonella species

A Gram-negative bacillus that is a common cause of urinary tract infections

Escherichia coli

A Gram-negative bacillus that produces a blue-green pigment and is associated with hospital-acquired infections

Pseudomonas aeruginosa

A Gram-negative bacillus that causes whooping cough

Bordetella pertussis

A Gram-negative bacillus that is a common cause of pneumonia and otitis media

Haemophilus influenzae

A Gram-negative bacillus that is an opportunistic pathogen and part of the normal gut flora

Klebsiella pneumoniae

A Gram-negative bacillus that causes bubonic plague

Yersinia pestis