MICROBIO (Intro)

Normal flora (human microbiota or microbiome)

Microorganisms that normally live on or inside the human body, including bacteria, fungi, viruses, and protozoa.

Colonization

The presence of microorganisms in the body without tissue invasion or symptoms.

Infectious dose

The number of organisms needed to cause infection.

Virulence

The ability of an organism to produce harmful factors and cause disease.

Gram-positive bacteria

Bacteria with a thick peptidoglycan layer that stain purple in Gram staining.

Gram-negative bacteria

Bacteria with a thin peptidoglycan layer and an outer membrane that contain LPS, staining pink in Gram staining.

Chemical functions of the cytoplasmic membrane

Active transport of molecules, energy generation, and synthesis of cell wall precursors in bacterial cells.

Bacterial spores

Formed inside vegetative bacterial cells to survive nutrient depletion, resistant to heat, dehydration, and chemicals.

Exotoxins

Secreted proteins produced by bacteria that can damage host tissues.

Endotoxins

Components of the outer membrane of Gram-negative bacteria, specifically LPS, which can cause fever and shock.

Mycoplasma pneumoniae

A bacterium that lacks a cell wall, making it resistant to beta-lactam antibiotics; diagnosed typically by PCR.

Acid-fast stain

A diagnostic test used for bacteria like Mycobacterium tuberculosis, which retains the stain due to its mycolic acid-rich cell wall.

Cytoplasm of bacteria

An amorphous matrix that houses ribosomes, plasmids, and the nucleoid.

Pili

Hair-like structures on bacteria that facilitate attachment to host cells.

Pathogenicity

The ability of a microorganism to cause disease.

Clinical significance of anaerobic bacteria

Anaerobic bacteria play roles in infections and are characterized by their growth in the absence of oxygen.

Streptococcus pyogenes

Group A Streptococcus, known for causing pharyngitis and other infections.

E. coli O157:H7

A strain of E. coli associated with severe foodborne disease, commonly found in undercooked beef.

Chlamydia trachomatis

An obligate intracellular bacterium, its NAAT is commonly used for diagnosis of STIs.

Treatment for MRSA (Methicillin-resistant Staphylococcus aureus)

Typically treated with Vancomycin.