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Mechanism of Action of Diphtheria Toxin

• Diphtheria toxin's mechanism of action involves the ribosylation and inactivation of elongation factor EF2.

Variability in Microbial Populations

• Variability involves repeated changes in the genotype at the molecular level.
• These changes are shown through a change in the phenotypic characteristics of microorganisms.

Ziehl-Neelsen Staining

• Mycobacterium species, when stained with Ziehl-Neelsen, appears red.

Key Factors of Bacterial Pathogenicity

• Bacterial pathogenicity factors include the capsule, which inhibits phagocytosis.
• Another factor is the bacterium’s capacity to produce toxins.
• Forming biofilms is another key attribute, including on medical devices.

Mechanisms of Resistance to Beta-Lactam Antibiotics

• Resistance can occur via modification of the antibiotic's target.
• Resistance can also occur through the production of beta-lactamases.
• Modification of bacterial permeability can also cause resistance.

Microscopic Identification of Gonorrhea

• A urethral secretion smear stained with methylene blue shows diplococci.
• The diplocci appear as coffee bean-shaped, positioned both inside and outside the cells.
• This is indicative of Neisseria gonorrhoeae (gonococcus).

Bacterial Conjugation via Sex Pili

• Conjugation occurs via F and R conjugative plasmids.
• This allows the transfer of plasmidic and chromosomal genetic material.

Clinical Signs of Infection

• Fever, chills, hypotension, and hypoventilation can suggest the release of bacterial components.
• These manifestations are common signs of infection.
• Lipopolysaccharide release due to the presence of gram-negative bacilli can cause severe symptoms.

Lysogenized Bacteria

• A lysogenized bacterium produces pathogenicity factors passed to descendants.
• It receives new genetic information allowing endotoxin production.

Bacterial Growth Requirements

• Growth factors are added to minimal culture media.
• Auxotrophic bacteria cannot synthesize them.

Pneumococcal Pathogenicity

• A non-encapsulated pneumococcus strain can become pathogenic if transformed by encapsulated strains.

Identifying Aromatic Bacteria

• Pseudomonas aeruginosa is a bacteria that emanates an aromatic odor
• A gram stain of Pseudomonas aeruginosa wil show gram negative under microscopy

Bacterial Growth Patterns on Culture Plates

• The propagation of a bacterial culture beyond the streak indicates flagella is active.

Key Differences between Bacterial and Eukaryotic Cytoplasm

• The structure and involvement of ribosomes in protein synthesis is a marked difference

Bacterial Mutation

• Mutations can result in bacterial resistance to various antibiotics.
• Mutations involve alterations in the nucleotide sequence.
• These occur spontaneously.

Bacterial Spores

• Bacterial spores are characterized by multiple layers.
• Spores are not actively metabolic
• Spores are resistant to boiling, but can be destroyed by steam autoclaving
• Spores are for multiplying bacteria

Composition and Role of the Outer Membrane

• The outer membrane is found in Gram-negative bacteria.
• The external membrane is lipopolysaccharide in nature

Antibiotics Active Against Gram-Negative Bacilli

• Ceftriaxone, a third-generation cephalosporin, is effective against Gram-negative bacilli.
• Ciprofloxacin is also effective against Gram-negative bacilli

Characteristics of Bacterial Glycocalyx

• Bacterial glycocalyx facilitates bacterial adhesion to surfaces.

Polysaccharide Capsules in Bacteria

• Streptococcus pneumoniae (pneumococcus) produces a capsule of polysaccharide nature.

Treating MRSA (Methicillin-Resistant Staphylococcus Aureus)

• Vancomycin can be used
• Linezolid can be used

Properties of R Plasmids

• R plasmids can transfer resistance to multiple antibiotics simultaneously.

Cell Wall Structure in Gram-Positive Bacteria

• Teichoic acids are present in Gram-positive bacteria's cell walls.
• However these are absent in Gram-negative bacteria.
• Gram-positive bacteria possess peptidoglycans in many layers

Action of Aminoglycoside Antibiotics

• Aminoglycoside antibiotics inhibit protein synthesis.
• They target the 30S ribosomal subunit.

Bacterial Structures for Colonization and Infection

• Bacterial pili (fimbriae) act as pathogenicity factors.
• These are involved in the colonization of mucosal surfaces and initial stages of infection.

Antibiotics for Tuberculosis Treatment

• Isoniazid, rifampicin, and ethambutol are used in tuberculosis treatment.

Obligate Aerobic Bacteria

• Obligate aerobes cannot develop without oxygen.
• Strict aerobes use molecular oxygen as the final electron acceptor.
• They have catalase and superoxide dismutase enzymes.

Transduction in Bacteria

• Transduction constitutes the transfer of genetic material
• Generalized transduction allows for the transfer of any gene from the donor cell's DNA.

What happens during the exponential phase of bacterial growth?

• During the exponential or log growth phase of bacteria a high degree of sensitivity to agents is observed

Appropriate use of Antibiotics

• Macrolides are suited to treat pneumonia due to mycoplasma