NURS 0068: Pathogens, Virulence Mechanisms, and Infectious Diseases

Comprehensive vocabulary flashcards covering pathogens, virulence mechanisms, transmission routes, diagnostics, and therapeutics across all 15 course modules.

Salmonella enterica

A Gram-negative, flagellated, facultatively anaerobic rod-shaped bacillus that can survive acidic stomach conditions and invades epithelial cells to induce proinflammatory cytokines, causing mucosal destruction and diarrhea.

Type III Secretion System (T3SS) in Salmonella

A specialized needle-like protein delivery system (injectisome) that mediates adhesion, secretion, membrane ruffling, and internalization into intestinal epithelial cells.

Salmonellosis Treatment Strategy

Primary supportive care emphasizing oral rehydration and electrolyte replacement; antibiotics such as fluoroquinolones and cephalosporins are strictly reserved for severe disease or high-risk populations to prevent prolonged bacterial shedding and resistance.

Rabies Virus (RBV)

A negative-sense, single-stranded, unsegmented, enveloped RNA virus with a rod- or bullet-shaped morphology belonging to the Lyssavirus genus of the Rhabdoviridae family.

Rabies Neuropathogenesis

A mechanism by which viral surface glycoproteins bind to and block nicotinic acetylcholine receptors in the brain, impairing neurotransmission and triggering characteristic frenzied behavior and pharyngeal spasms.

Direct Fluorescent Antibody (DFA) Test for Rabies

The post-mortem diagnostic gold standard for animals that detects rabies antigens in brain tissue, appearing microscopically as distinct green fluorescent particles.

Rabies Post-Exposure Prophylaxis (PEP)

A post-exposure medical regimen comprising immediate wound cleansing with soap and water, application of povidone-iodine or alcohol, infiltration of Human Rabies Immune Globulin (HRIG), and vaccination on days $0$, $3$, $7$, and $14$ for unvaccinated patients.

Clostridioides difficile

A Gram-positive, anaerobic, non-motile, endospore-forming bacillus that colonizes the gastrointestinal tract following antibiotic disruption of the native microbiota, producing toxins that cause pseudomembranous colitis.

Toxin A (TcdA)

An enterotoxin produced by Clostridioides difficile that increases intestinal mucosal permeability, disrupts the epithelial brush border, stimulates fluid secretion, and provokes intense local inflammation.

Toxin B (TcdB)

A potent cytotoxin of Clostridioides difficile that enters host cells and inactivates small Rho GTPases, depolymerizing the actin cytoskeleton, destroying tight junctions, and initiating colonic epithelial apoptosis.

Fidaxomicin and Vancomycin for C. diff

First-line oral antibiotic treatments for Clostridioides difficile infections; oral vancomycin acts locally in the bowel lumen to kill Gram-positive pathogens, while fidaxomicin targets intestinal vegetative cells over a $7$ to $10\text{ day}$ regimen.

Hepatitis A Virus (HAV)

A non-enveloped, positive-sense single-stranded RNA virus of the Picornaviridae family (genus Hepatovirus) with an icosahedral capsid that replicates in the cytoplasm of hepatocytes.

HAV Dual Phenotypes

The coexistence of naked virions that provide environmental stability for fecal-oral spread and host-derived quasi-enveloped virions that facilitate stealth bloodborne transmission while evading circulating neutralising antibodies.

Anti-HAV IgM

A serum immunoglobulin M antibody whose detection confirms acute Hepatitis A infection, as HAV is not routinely cultured clinically due to low sensitivity and extended propagation times.

Measles morbillivirus

An enveloped, spherical, non-segmented negative-sense single-stranded linear RNA virus that infects respiratory epithelial cells and replicates within host cell cytoplasm.

Hemagglutinin (H) and Fusion (F) Proteins

Key surface virulence proteins of the measles virus; the H protein binds to host cell surface receptors, activating the F protein to mediate viral envelope-host membrane fusion and syncytia formation.

MMR Vaccine

A live-attenuated vaccine administered against measles, mumps, and rubella that demonstrates a protective efficacy rate of $93\%$ to $97\%$.

Borrelia burgdorferi

A microaerophilic Gram-negative spirochete characterized by periplasmic endoflagella, an outer membrane rich in surface lipoproteins rather than lipopolysaccharide (LPS), and a linear chromosome accompanied by linear and circular plasmids.

Erythema migrans

The expanding cutaneous rash associated with early localized Lyme disease occurring $3$ to $30\text{ days}$ post-tick bite, appearing as bullseye lesions with central clearing, blistering, uniformly red, or disseminated macules.

OspA and OspC

Outer surface proteins of Borrelia burgdorferi; OspA anchors the spirochete inside the tick midgut, whereas blood meal ingestion triggers OspA downregulation and OspC upregulation to facilitate salivary migration and mammalian infection.

Two-Tier Serologic Testing for Lyme Disease

The recommended diagnostic protocol comprising a sensitive first-tier enzyme immunoassay (EIA), followed by a confirmatory second-tier Western blot or modified immunoassay (STTT or MTTT) if the initial result is positive or equivocal.

Mycobacterium tuberculosis

A slow-growing, strictly aerobic, acid-fast rod whose complex cell wall contains arabinogalactan, peptidoglycan, and abundant mycolic acids that resist decolorization and chemical damage.

Cord Factor

A glycolipid virulence factor (trehalose 6,6'-dimycolate) produced by Mycobacterium tuberculosis that causes serpentine arrangement of bacterial cells, inhibits phagosome-lysosome fusion, and induces granuloma formation.

Interferon-Gamma Release Assay (IGRA)

An in vitro blood test that measures cell-mediated release of interferon-gamma by circulating T lymphocytes stimulated with specific Mycobacterium tuberculosis antigens.

Vibrio cholerae

A Gram-negative, comma-shaped motile rod with a single polar flagellum that is halotolerant and causes severe cholera via toxigenic $O1$ and $O139$ serogroups.

Cholera Toxin (CT)

An enterotoxin produced by Vibrio cholerae that targets small intestinal enterocytes, continuously activating adenylate cyclase to drive extensive fluid and ion outflow, generating profuse 'rice-water stool'.

TCBS Agar

Thiosulfate-citrate-bile salts-sucrose agar, a selective and differential growth medium formulated with high alkaline pH to isolate and identify Vibrio cholerae from clinical stool specimens.

Treponema pallidum

A microaerophilic spirochete with endoflagella, minimal exposed outer membrane proteins, and antigenically variable surface structures, serving as the causative agent of syphilis.

Chancre

A painless, indurated, highly infectious ulcerative skin lesion that develops at the portal of entry during primary syphilis approximately $3$ to $6\text{ weeks}$ after exposure.

Penicillin G

The definitive first-line beta-lactam antibiotic used across all stages of syphilis that kills Treponema pallidum by irreversibly inhibiting bacterial cell wall peptidoglycan synthesis.

Toxic Shock Syndrome Toxin-1 (TSST-1)

A pyrogenic superantigen exotoxin synthesized by Staphylococcus aureus that binds simultaneously to MHC class II molecules and T-cell receptor beta chains, causing massive systemic cytokine storms, severe hypotension, and shock.

Streptococcus pyogenes in TSS

A Gram-positive coccus that grows in chains and secretes pyrogenic exotoxin A, causing streptococcal toxic shock syndrome characterized by soft tissue infection and rapid organ collapse.

Staphylococcal Protein A

An immune-evasion cell wall protein expressed by Staphylococcus aureus that binds the Fc portion of IgG antibodies, preventing Fc receptor-mediated opsonization and phagocytic clearance.

Human Immunodeficiency Virus (HIV)

An enveloped retrovirus containing two identical positive-sense single-stranded RNA molecules, reverse transcriptase, integrase, and protease, using glycoproteins gp120 and gp41 to infect host $CD4^+$ T lymphocytes.

Acute HIV Infection Syndrome

The early phase of HIV infection occurring $2$ to $4\text{ weeks}$ post-transmission, characterized by high viral replication, lymphadenopathy, fever, chills, fatigue, sore throat, and mouth ulcers.

4th-Generation HIV Immunoassay

A diagnostic screening test that simultaneously detects circulating HIV-1 and HIV-2 antibodies along with the HIV-1 $p24$ viral capsid antigen in human blood specimens.

Yersinia pestis

A Gram-negative, facultatively anaerobic coccobacillus that causes bubonic, septicemic, and pneumonic plague, exhibiting bipolar 'safety-pin' staining when colored with Wright, Giemsa, or Wayson stains.

Yersinia Outer Proteins (Yops)

Effector proteins delivered directly into mammalian host immune cells via a plasmid-encoded Type III Secretion System to paralyze phagocytosis, disrupt actin filaments, and trigger host cell apoptosis.

Bubo

A markedly enlarged, intensely painful, and necrotic regional lymph node characteristic of bubonic plague that develops following the bite of an infected flea vector.

Clostridium botulinum

An obligately anaerobic, Gram-positive, endospore-forming rod bacterium found in soil and aquatic environments that secretes potent neurotoxins under low-acid, oxygen-depleted conditions.

Botulinum Neurotoxin (BoNT)

A zinc-dependent metalloprotease that specifically cleaves SNARE proteins at presynaptic neuromuscular junctions, arresting acetylcholine vesicle exocytosis and producing descending flaccid paralysis.

Infant Botulism

A toxicoinfection resulting from the ingestion of Clostridium botulinum endospores (frequently associated with raw honey) that colonize the immature infant gut and generate toxin in vivo.

SARS-CoV-2 Spike (S) Protein

A surface glycoprotein that features a furin cleavage site and binds with high affinity to human host cell angiotensin-converting enzyme 2 (ACE2) receptors to mediate viral entry and membrane fusion.

Nonstructural Protein 1 (Nsp1)

A virulence factor of SARS-CoV-2 that inserts into the host ribosomal mRNA entry channel, repressing host translation and stifling the early interferon-mediated innate immune response.

Plasmodium falciparum

The protozoan parasite responsible for the most severe and fatal cases of malaria in humans, transmitted via the parenteral bite of infected female Anopheles mosquitoes.

Hypnozoites

Dormant parasitic liver stages formed by Plasmodium vivax and Plasmodium ovale that can reactivate months or years post-primary infection to precipitate malaria relapses.

Artemisinin-Based Combination Therapy (ACT)

A dual-action antimalarial drug regimen combining an artemisinin derivative with a partner compound to disrupt parasite metabolic multiplication while mitigating drug resistance development.