Microbiology Lecture Series: The Bacterial Cell to Bacteriophages

Comprehensive vocabulary flashcards covering bacterial structure, specific pathogens (Plague, Cholera), opportunistic infections (VRSA, Necrotizing Fasciitis), antibiotic mechanisms, and bacteriophage biology based on the provided lecture notes.

Cytoplasm

The dense, enzyme- and ribosome-rich interior of the bacterial cell.

Nucleoid

The region in a bacterial cell containing chromosomal DNA that is not membrane-bound.

Cytoplasmic (plasma) membrane

A selective barrier involved in energy generation for the bacterial cell.

Cell wall

A rigid outer layer of the bacterial cell that maintains its shape and resists internal turgor pressure.

FtsZ

A protein that localizes to the midcell to organize bacterial cell division.

Peptidoglycan

A tough, stretchy fabric covering the bacterial cell composed of repeating NAG–NAM glycan chains with peptide crosslinks.

Cocci

Spherical bacterial cell shape.

Bacilli

Rod-like bacterial cell shape.

Spirilla

Curved bacterial cell shape.

Mur enzymes

Cytoplasmic enzymes that build the peptidoglycan precursor on a lipid carrier.

Lipid II

The complete peptidoglycan subunit consisting of NAG–NAM and a peptide attached to a lipid carrier.

Flippase

The enzyme responsible for transporting Lipid II across the cytoplasmic membrane.

Penicillin-binding proteins (PBPs)

Essential enzymes that extend glycan chains (transglycosylation) and crosslink peptides (transpeptidation) in the cell wall; key targets for antibiotics.

$\beta$-lactams

A class of antibiotics, including penicillins and cephalosporins, that disrupt cell wall assembly leading to bacterial lysis.

Virulence

The degree of damage caused to a host by a pathogen.

Outbreak

A small localized surge in morbidity and mortality in a single community.

Epidemic

A regional surge in disease over a large area, such as multiple cities.

Pandemic

An epidemic with transnational spread over multiple continents.

Yersinia pestis

The gram-negative, facultatively anaerobic, non-mobile bacterium that causes the plague.

F1 capsule

A virulence mechanism of Y. pestis that prevents phagocytosis by host immune cells.

Type III secretion system (Yops)

A mechanism that injects proteins into host immune cells to block phagocytosis and cytokine signaling.

Pla (plasminogen activator protease)

An enzyme that breaks down fibrin clots, allowing bacteria to spread through tissues and the bloodstream.

Disseminated Intravascular Coagulation (DIC)

A dangerous condition where the body’s clotting system becomes overactivated, often triggered by endotoxin (LPS) during plague.

Enzootic

A cycle of disease involving rodents and fleas where human risk remains low.

Epizootic

A cycle involving rodent die-offs, resulting in a high risk of disease spillover to humans.

Bubonic presentation

The most common clinical form of plague, characterized by painful, swollen lymph nodes (buboes) and transmitted through flea bites.

Septicemic presentation

A form of plague involving the bloodstream, characterized by fever, prostration, and acral gangrene.

Pneumonic presentation

A highly fatal form of plague involving overwhelming pneumonia and bloody sputum, transmitted via respiratory droplets.

Tc toxin complexes

Multi-component toxins where TcA delivers the toxin and TcB/TcC carry out cytotoxic activity by disrupting the host cell cytoskeleton.

Miasma theory

The historical belief that diseases were caused by "bad" or malodorous air.

Colonization factors

Bacterial traits, such as the toxin-coregulated pilus (TCP) in V. cholerae, that allow bacteria to attach, persist, and replicate without necessarily causing symptoms.

Virulence factors

Bacterial products, such as cholera toxin (CT), that directly cause host pathology and disease symptoms.

Vibrio cholerae

A gram-negative, motile, facultative anaerobe found in brackish water that causes severe diarrheal illness.

CTX$\phi$

A lysogenic bacteriophage that encodes the cholera toxin and inserts its DNA into the V. cholerae genome.

Horizontal gene transfer

The process by which an organism transfers genetic material to another organism that is not its offspring.

Lytic strategy

A bacteriophage life cycle where the virus replicates and then lyses the bacterial cell.

Lysogenic strategy

A bacteriophage life cycle where the viral DNA integrates into the bacterial genome.

Opportunistic infection

A disease caused by a microorganism (often a member of the normal flora) that occurs only when host defenses are compromised or the environment changes.

Staphylococcus aureus

A coagulase-positive, gram-positive cocci that is a common inhabitant of skin and a major opportunistic pathogen.

Biofilm

A viscous extracellular glycoconjugate (slime) that allows bacteria to adhere to surfaces and protected from neutrophils and antibiotics.

Vancomycin

A glycopeptide antibiotic that inhibits peptidoglycan crosslinking by binding to D-Ala-D-Ala residues.

VanA operon

A set of genes (vanH, vanA, vanX, vanY) often carried on the transposon Tn1546 that confers vancomycin resistance by altering peptidoglycan precursors to D-Ala-D-Lac.

Streptococcus pyogenes

A Group A streptococcus that can cause invasive infections like necrotizing fasciitis.

Necrotizing fasciitis

A catastrophic opportunistic infection resulting in the death of subcutaneous fat tissue and underlying fascia.

Carbon Catabolite Repression (CCR)

A regulatory mechanism mediated by CcpA that conserves energy by repressing certain operons; in Streptococcus, high glucose levels lead to less streptolysin (SLS) expression.

Salvarsan

The first synthetic drug development against syphilis, pioneered by Paul Ehrlich in 1910.

Macrolides

Antibiotics like erythromycin that bind to the 50S subunit of bacterial ribosomes to stop protein synthesis.

Tetracyclines

Antibiotics like doxycycline that bind to the 30S subunit of bacterial ribosomes to stop protein synthesis.

DNA gyrase inhibitors

Antibiotics that prevent bacteria from unwinding DNA, thereby blocking replication and division.

Resistome

The vast, interconnected pool of antibiotic resistance genes existing in pathogenic and non-pathogenic bacteria across various environments.

Bacteriophages

Viruses that specifically infect and replicate within bacteria; they are ubiquitous and highly host-specific.

CRISPR-Cas

An adaptive bacterial immune system that captures fragments of phage DNA (spacers) into an array to recognize and cleave invading nucleic acids during reinfection.