Bacterial Infections Flashcards
(31 cards)
How are bacteria classified? By shape
By shape, Gram stain reaction, growth characteristics, and antigenic structure.
What are the three common bacterial shapes?
Coccus (spherical), Bacillus (rod-shaped), Spiral.
What does Gram-positive mean?
Bacteria retain crystal violet dye due to think peptidoglycan layer in the cell wall
What does Gram-negative mean?
Bacteria do not retain violet dye and appear red/pink after counterstaining
What is modern bacterial taxonomy based on?
Genomic sequence especially 16S ribosomal RNA.
Where are Staphylococci commonly found?
On skin and in the nasal cavity.
What shape and Gram type are Staphylococci?
Gram-positive cocci in clusters.
Are Staphylococci normally harmful?
No they are opportunistic pathogens.
What toxins can Staphylococcus aureus produce?
Toxins causing vomiting and diarrhea, TSS, hemolysis, and tissue necrosis
What are some common Staphylococcus aureus infections? Skin infections
Skin infections, sepsis, pneumonia, osteomyelitis, endocarditis.
What is MRSA?
Methicillin-resistant Staphylococcus aureus — resistant to common antibiotics.
What shape and Gram type are Streptococci?
Gram-positive cocci in chains or pairs.
Where are Streptococci normally found?
Skin, mouth, pharynx, gut, female genital tract.
What types of infections do Streptococci cause?
Pyogenic (pharyngitis), toxigenic (scarlet fever), immunologic (rheumatic fever).
What are Clostridia?
Anaerobic spore-forming Gram-positive bacilli.
What does Clostridium tetani cause?
Tetanus — prevents muscle relaxation by blocking inhibitory neurotransmitters.
What does Clostridium botulinum cause?
Botulism — prevents muscle contraction by blocking acetylcholine.
What does Clostridium difficile cause?
Intestinal colitis (C. diff infection).
What shape and Gram type is Neisseria?
Gram-negative cocci.
What diseases are caused by Neisseria?
Meningitis (Neisseria meningitidis),
Gonorrhea (Neisseria gonorrhoeae).
What organism causes Lyme disease?
Borrelia burgdorferi.
How is Lyme disease transmitted?
By the bite of an infected tick.
What are the stages of untreated Lyme disease?
Early rash, followed by neurologic, cardiac, and joint symptoms, then chronic issues.
What are the general mechanisms of antibiotic action?
Inhibit cell wall, cell membrane, nucleic acid or protein synthesis.
