Biology 134 – The Big Bacteria Exam Study Guide

A comprehensive vocabulary flashcard set based on Biology 134 Study Guides #C1 and #C2, covering Gram-positive and Gram-negative bacteria, major toxins, pathogenesis, and clinical conditions.

Staphylococcus

Gram-positive, facultative anaerobic cocci arranged in grape-like clusters that test positive for catalase.

Catalase test

Diagnostic biochemical test used to differentiate Staphylococcus ($\text{catalase positive}$) from Streptococcus ($\text{catalase negative}$).

Hemolysis

The breakdown of red blood cells (RBCs); differentiated into alpha (partial breakdown), beta (total breakdown), and gamma (no breakdown).

Exotoxin

A toxic protein secreted by living bacterial cells into their surrounding environment that causes harm to human hosts.

Superantigen

An antigen that stimulates a massive, overblown generalized immune response, producing a smokescreen effect that shields the microbe from specific immune targeting.

Bacteremia

An infection marked by the active presence of bacteria within the bloodstream, capable of leading to sepsis and septic shock.

Septic shock

A critical, sudden drop in blood pressure caused by widespread systemic inflammation following a massive immune response.

Toxic shock syndrome

A rapid-onset form of shock caused by bacterial exotoxins circulating in the blood, such as from the colonization of tampons by Staphylococcus aureus.

Staphylococcal food poisoning

An intoxication resulting from ingesting preformed Staphylococcus aureus exotoxins on contaminated food, hallmarked by a rapid onset of $30\,\text{m}$ to $8\,\text{hr}$ and violent vomiting.

MRSA

Methicillin-resistant Staphylococcus aureus; a pathogen of grave clinical concern because methicillin historically served as one of the most effective antimicrobial treatments against S. aureus.

Streptococcus

Gram-positive, facultative anaerobic cocci arranged in chains that test negative for catalase.

Lancefield groups

A classification scheme that categorizes Streptococcus species based on distinct carbohydrate antigens present within their cell walls.

Strep throat

A non-invasive pharyngeal infection (pharyngitis) caused by Group A Streptococcus; symptoms include severe sore throat, fever, and white spots on the throat.

Scarlet fever

A non-invasive Group A streptococcal throat infection presenting with the classic symptoms of strep throat alongside a characteristic diffuse red body rash.

Impetigo

A localized superficial skin infection marked by pustules that rupture, weep, and form honey-colored crusts.

Necrotizing fasciitis

An invasive 'flesh-eating' bacteremia wherein bacterial enzymes rapidly destroy subcutaneous fascia and muscular tissue, ultimately resulting in death via toxic shock.

Rheumatic fever

An advanced autoimmune sequela of untreated strep throat that attacks synovial joints and heart valves.

Streptococcus agalactiae

Group B Streptococcus, the leading cause of neonatal meningitis; prevented by prophylactic antibiotic administration to the mother prior to or during childbirth.

Pneumonia

A pulmonary infection in which inflammatory fluid accumulates within the alveoli, causing impaired respiratory gas exchange and difficulty breathing.

Streptococcus pneumoniae

Gram-positive lancet-shaped coccus (termed the pneumococcus) responsible for the most common form of bacterial pneumonia.

Expectorant

A pharmaceutical agent that thins and loosens respiratory mucus, reducing bacterial proliferation by enabling physical clearance from the lungs.

Meningitis

Inflammation of the protective meninges covering the brain and spinal cord, presenting with severe head and neck pain, fever, nausea, vomiting, convulsions, and coma.

Streptococcus mutans

Oral commensal bacterium that causes dental caries and can cause subacute bacterial endocarditis in patients with prosthetic heart valves.

Enterococcus

Gram-positive, bile-resistant, facultative anaerobic cocci; the only Gram-positive cocci commonly causing urinary tract infections ($\text{UTIs}$), frequently demonstrating high antibiotic resistance.

Nosocomial infection

An infection acquired by a patient inside a healthcare or hospital environment; accounts for approximately $13\%$ of all $\text{UTIs}$.

Lactococcus

Gram-positive cocci appearing primarily in pairs that ferment lactose to produce lactic acid (curdling milk to yield cheese) and secrete the bacteriocin nisin.

Nisin

An antimicrobial peptide produced by Lactococcus species that exhibits antibacterial activity, primarily inhibiting other Gram-positive bacteria.

Bacillus cereus

A spore-forming Gram-positive soil rod that colonizes starchy foods, causing either mild rapid-onset food poisoning or more severe long-onset food poisoning.

Bt toxin

An insecticidal protein derived from Bacillus thuringiensis that is lethal to specific insect orders but safe for mammalian consumption; integrated into genetically modified ($\text{GM}$) crops.

Bacillus anthracis

An endospore-forming, Gram-positive rod bacterium that serves as the etiologic agent of anthrax.

Cutaneous anthrax

The most common natural form of anthrax infection, marked by malaise, low-grade fever, and painless black necrotic ulcers (eschars) on the skin.

Pulmonary anthrax

Inhalation anthrax; characterized by mild fever, cough, and chest pain, followed by macrophage-mediated dissemination to the blood, culminating in severe septic shock with a $100\%$ untreated mortality rate.

Clostridium tetani

A Gram-positive, obligate anaerobic, endospore-forming rod that non-invasively secretes neurotoxins, resulting in rigid, spastic paralysis.

Tetanospasmin

A potent neurotoxic exotoxin produced by Clostridium tetani that binds permanently to inhibitory interneurons, precipitating lockjaw, bone-fracturing spastic contractions, and respiratory arrest.

Gas gangrene

An invasive clostridial infection in which microbial gas production displaces oxygen from neighboring healthy tissue, forming palpable subcutaneous gas bubbles.

Debridement

The surgical removal of dead or devitalized tissue; crucial in managing Clostridium infections because these obligate anaerobes rapidly proliferate through necrotic tissue.

Botulinum toxin

A neurotoxin produced by Clostridium botulinum that blocks peripheral acetylcholine release, inducing flaccid paralysis; recovery requires months because damaged nerve terminals must regenerate.

Infant botulism

An active true enteric infection occurring when ingested Clostridium botulinum spores germinate and synthesize neurotoxin within the infant gastrointestinal tract.

Antibiotic-associated diarrhea

Diarrhea precipitated by broad-spectrum antibiotic usage, which eradicates competitive normal gut microflora and allows Clostridioides difficile to proliferate.

Pseudomembranous colitis

Severe inflammatory disease of the colon caused by Clostridioides difficile, characterized by the development of pseudomembranous plaques along the intestinal mucosa.

Pseudomembrane

A thick, inflammatory fibrinous biofilm composed of dead epithelial cells, leukocytes, and bacterial debris; characteristic of C. difficile colitis and diphtheria.

Fecal Microbiota Transplantation (FMT)

A therapeutic procedure wherein processed stool containing healthy commensal bacteria from a donor is infused into a patient's colon to re-establish a balanced microbiome.

Corynebacterium diphtheriae

Gram-positive, pleomorphic, facultative anaerobic rod that non-invasively secretes a bacteriophage-encoded exotoxin that halts eukaryotic protein synthesis.

Listeria monocytogenes

A Gram-positive, non-spore-forming, psychrotrophic, and halophilic rod that evades the host immune system by using host actin polymerization to spread directly from cell to cell.

Mycobacterium tuberculosis

An obligate aerobic, slow-growing, acid-fast bacillus possessing a waxy mycolic acid cell wall that initially infects and persists inside alveolar macrophages.

Tubercles

Granulomatous concentric aggregates of macrophages, immune cells, and Mycobacterium tuberculosis bacilli formed in the lungs to wall off infection.

Tuberculosis infection progression

Inhaled droplets lead to no infection in $10\%-20\%$ of cases and macrophage engulfment in $80\%-90\%$ ($\text{TB test } +$). Of infected cases, $90\%-95\%$ clear the infection ($\text{TB test } -$) while $5\%-10\%$ develop primary active disease within $2\,\text{years}$; latent bacilli may remain dormant for decades or reactivate into recurrent disease and extrapulmonary dissemination.

Hansen's disease

Leprosy; a chronic infection of the peripheral nervous system and skin caused by Mycobacterium leprae, producing sensory loss, muscle weakness, and disfigurement, carried naturally by armadillos.

Streptomyces

Gram-positive, obligate aerobic, filamentous soil bacteria responsible for the earthy petrichor scent of soil and the biological source of approximately $\frac{2}{3}$ of naturally derived clinical antibiotics.

Enterobacteriaceae

A large taxonomic family of Gram-negative, facultative anaerobic bacilli indigenous to the gastrointestinal tract, including Escherichia, Salmonella, Klebsiella, Enterobacter, Shigella, Yersinia, and Proteus.

Hemolytic Uremic Syndrome (HUS)

A life-threatening clinical syndrome resulting from bacterial toxin damage to renal capillary beds, causing widespread microangiopathic red blood cell destruction and acute kidney failure.

Shiga toxin

A potent bacteriophage-encoded cytotoxin (verocytotoxin) produced by Shigella and STEC strains that halts eukaryotic protein synthesis by cleaving and inactivating ribosomal subunits.

Shigellosis

A dysenteric gastrointestinal infection caused by invasive Shigella species, marked by severe abdominal cramps, high fever, watery stool progressing to blood, and fecal pus.

Typhoid fever

A systemic bacterial illness caused by typhoidal Salmonella that invades mesenteric lymphatic tissue, multiplying within the liver, spleen, and gallbladder before entering the bloodstream.

Typhoid carrier

A clinically recovered, asymptomatic individual who chronically harbors and sheds typhoidal Salmonella from their gallbladder.

Vibrio cholerae

A comma-shaped (curved) Gram-negative bacillus that secretes an enterotoxin inducing severe, non-inflammatory, highly voluminous watery diarrhea ('rice-water stools') without fever.

Helicobacter pylori

An acidophilic, spiral Gram-negative rod that colonizes the gastric mucosa and utilizes urease to survive gastric acidity, contributing to peptic ulcers; up to $70\%$ of infected individuals remain asymptomatic.

Pseudomonas aeruginosa

A Gram-negative, obligate aerobic rod and opportunistic pathogen with broad intrinsic antibiotic resistance, known for colonizing burn wounds, cystic fibrosis patients, and immunocompromised hosts.

Fastidious organism

A microorganism possessing complex, highly specific nutritional and physiological requirements that make it exceptionally challenging to culture in standard in vitro conditions.

Legionnaire's disease

A severe atypical pneumonia caused by inhaling aerosolized Legionella pneumophila from environmental water sources, uniquely presenting with high fever, pulmonary fluid, and diarrhea.

Bordetella pertussis

A Gram-negative, obligate aerobic coccobacillus that causes whooping cough (pertussis) by binding to ciliated respiratory epithelium and paralyzing cilia with tracheal cytotoxin.

Pertussis toxin

An exotoxin secreted by Bordetella pertussis that causes host respiratory mucosal epithelial cells to oversecrete copious quantities of mucus.

Mycoplasma pneumoniae

A wall-less, highly pleomorphic bacterium that causes walking (atypical) pneumonia; intrinsically resistant to all beta-lactam and cell-wall-targeting antibiotics.

Haemophilus influenzae strain B (Hib)

A virulent Gram-negative coccobacillus historically responsible for severe infant meningitis, bacteremia, and epiglottitis, now nearly eradicated in the US by conjugate vaccination.

Neisseria meningitidis

A Gram-negative obligate aerobic diplococcus ('meningococcus') capable of causing epidemic meningitis spread via respiratory droplets; characterized by fever, stiff neck, and a non-blanching rash.

Non-blanching rash

A petechial or purpuric rash that fails to turn pale or white when localized pressure is applied (as in the glass test); an indicator of meningococcal bacteremia.

Neisseria gonorrhoeae

A Gram-negative diplococcus ('gonococcus') transmitted via sexual contact; causes purulent urethritis in males, cervicitis in females, and can ascend to cause pelvic inflammatory disease, sterility, or septic arthritis.

Septic arthritis

Direct infectious invasion and inflammatory destruction of a joint capsule and its synovial fluid by viable bacterial microorganisms.

Reactive arthritis

A sterile, autoimmune-mediated inflammatory arthropathy occurring as a secondary immune reaction following an infection located elsewhere in the body.

Elementary body (EB)

The small, extracellular, metabolically inert, rigid-walled infectious stage in the developmental cycle of Chlamydia.

Reticulate body (RB)

The larger, intracellular, metabolically active, replicating, but non-infectious stage in the developmental cycle of Chlamydia.

Trachoma

A chronic ocular infection caused by Chlamydia trachomatis transmitted by mechanical vectors (flies) and fomites; the leading cause of preventable infectious blindness.

SAFE strategy

The World Health Organization's public health protocol aimed at eliminating blinding trachoma: Surgery, Antibiotics, Facial cleanliness, and Environmental improvement.

Chancre

A hard, painless, highly infectious cutaneous ulcer that appears at the primary inoculation site during primary syphilis.

Gummas

Painful, soft, destructive granulomatous lesions of necrosis and inflammation that develop in bones, skin, and organs during tertiary syphilis.

Borrelia burgdorferi

A Gram-negative spirochete transmitted by Ixodes ticks from animal reservoirs to humans that causes Lyme disease, characterized by an early bullseye rash (erythema migrans).

Francisella tularensis

A highly infectious Gram-negative coccobacillus transmitted by small mammals ('rabbit fever') that infects macrophages; inhalation causes severe pneumonia with enlarged hilar lymph nodes on X-ray.

Yersinia pestis

A Gram-negative bacillus transmitted by fleas from rodents that causes bubonic plague, characterized by intensely swollen, necrotic lymph nodes called buboes.