Gram-positive bacteria

Gram-positive bacteria are a type of bacteria that are classified by the color they turn after a chemical called Gram stain is applied to them. Gram-positive bacteria turn blue when this stain is applied, while Gram-negative bacteria do not.

Characteristics

Gram-positive bacteria have a thick cell wall that is rich in peptidoglycan. This cell wall is responsible for the bacteria's ability to retain the Gram stain. In addition to the cell wall, some Gram-positive bacteria have a layer of polysaccharide or teichoic acid on their surface.

Types of Gram-positive bacteria

There are many types of Gram-positive bacteria, including:

• Staphylococcus
• Streptococcus
• Enterococcus
• Listeria
• Bacillus
• Clostridium

Diseases caused by Gram-positive bacteria

Gram-positive bacteria can cause a variety of diseases, including:

• Staphylococcus aureus can cause skin infections, pneumonia, and food poisoning.
• Streptococcus pneumoniae can cause pneumonia, meningitis, and otitis media.
• Enterococcus faecalis and Enterococcus faecium can cause urinary tract infections, bacteremia, and endocarditis.
• Listeria monocytogenes can cause listeriosis, a serious infection usually caused by eating food contaminated with the bacteria.
• Bacillus anthracis causes anthrax, a rare but serious illness.
• Clostridium difficile causes infections that can range from diarrhea to life-threatening inflammation of the colon.

Treatment

Gram-positive bacteria are usually sensitive to penicillin and other beta-lactam antibiotics. However, some Gram-positive bacteria have developed resistance to these antibiotics, making treatment more difficult.

See also

• Gram-negative bacteria
• Bacterial cell structure
• Antibiotic resistance

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  Gram stain of Bacillus anthracis
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  Gram stain showing Gram-positive bacteria
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  Diagram of Gram-positive cell wall
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  Schematic of Gram-positive cell wall
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  Classification of Gram-positive bacteria
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  Structure of murein in Gram-positive bacteria
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  Actinomyces species under microscope