MTLE Review - Clinical Bacteriology (Video) Flashcards

A comprehensive set of flashcards covering key concepts in clinical bacteriology from the MTLE notes, including prokaryotic structure, growth, genetics, safety, and control methods.

What is a prokaryotic cell characterized by having no true nucleus called?

Nucleoid; prokaryotes lack a membrane-bound nucleus and organelles.

Where is energy production typically located in prokaryotic cells?

In the cytoplasmic (plasma) membrane, equivalent to mitochondria in eukaryotes.

What is the typical haploid genetic state of prokaryotes?

Haploid with a single chromosome; plasmids may be present.

Which organisms lack a cell wall of peptidoglycan (as noted in the notes)?

Mycoplasma and Ureaplasma.

What is the hallmark of bacterial cell wall composition that is the main target of many antibiotics?

Peptidoglycan (glycan chains of NAG-NAM).

What are the two major toxin types produced by bacteria?

Exotoxins and endotoxins.

What virulence factor enables bacteria to attach to surfaces and form biofilms?

Biofilms.

Differentiate virulence from pathogenicity.

Virulence: degree of pathogenicity; pathogenicity: ability to cause disease. Virulence is often measured by infectious dose.

What test identifies encapsulated organisms by causing capsule swelling?

Neufeld-Quellung test.

Which capsular antigens are used in serotyping, and which organisms are commonly referenced?

Somatic O antigen (heat-stable); Vi antigen (Salmonella) and K antigen (E. coli) (heat-labile).

What staining method is used to demonstrate encapsulated bacteria?

Acid-fast? No. Capsule swelling tests like Quellung. Capsule visualization often uses specific staining and background contrast.

Which toxins are released by living gram-positive bacteria and do not require cell death for release?

Exotoxins; mainly protein in nature.

Which toxin is part of the lipopolysaccharide (LPS) and is released upon bacterial cell death?

Endotoxin (LPS) from Gram-negative bacteria.

Name two tetanus and botulism toxins and their organisms.

Tetanus toxin (tetanospasmin) from Clostridium tetani; Botulinum toxin from Clostridium botulinum.

What is the composition and characteristic of endotoxins in terms of stability and immunogenicity?

Part of LPS; heat-stable, poorly immunogenic, not easily neutralized by antitoxin; cannot be converted into toxoid.

Which component is characteristic of Gram-positive cell walls and absent in Gram-negative cell walls?

Teichoic acids present in Gram-positive walls; absent from Gram-negative walls.

What is the key component that gives acid-fast bacteria their acid-fast property?

Mycolic acid in the cell wall.

Which organism is known for producing a poly-D-glutamic acid capsule?

Bacillus anthracis.

What are L-forms in bacteria?

Organisms that temporarily lack their cell wall due to environmental conditions.

Which bacteria lack a cell wall and are often used as examples in labs?

Mycoplasma and Ureaplasma.

What is the basic basis for Gram staining and why?

Cell wall structure; Gram-positive (thick peptidoglycan with teichoic acids) retains crystal violet; Gram-negative (thin peptidoglycan; no teichoic acid) does not.

What are the two major sections of the bacterial cell wall that are commonly discussed (capsule, pili, etc.)?

Capsule, cell wall (peptidoglycan), cell membrane; pili; endospore; flagella.

What test detects encapsulated organisms by inducing capsule swelling due to antigen-antibody reactions?

Capsular swelling test (Quellung reaction).

What is the term for the structure that aids in adhesion and gene transfer in bacteria?

Pili (Fimbriae); includes sexual (conjugation) pili for DNA transfer.

Which structural feature is the site of attachment for bacteria to host cells and the site of conjugation?

Pili/fimbriae; sex pili facilitate DNA transfer between bacteria.

What stain is used to visualize endospores (Schaeffer-Fulton method)?

Schaeffer-Fulton staining method.

Which bacteria genera commonly form endospores?

Bacillus and Clostridium (e.g., B. anthracis, C. tetani, C. botulinum).

What are the motility classifications based on flagella arrangement?

Atrichous, Monotrichous, Amphitrichous, Lophotrichous, Peritrichous.

What antigen is associated with the flagellum and serves as an important antigenic marker?

H antigen (flagellin protein).

Which motility patterns are observed in bacteria?

Tumbling, Gliding, Twitching, Darting, Corkscrew, Shooting star motility.

Name a method used to demonstrate bacterial motility aside from observing growth patterns.

Flagellar stain with tannic acid; hanging drop; semi-solid media.

What are metachromatic (volutin) granules and give examples of bacteria that form them?

Inclusions/granules used for energy storage (polyphosphates); examples: Corynebacterium, M. tuberculosis (among others).

Where is bacterial DNA primarily located and is it surrounded by a nuclear membrane?

Nucleoid region; not enclosed by a nuclear membrane.

What is the bacterial ribosome type and its subunit composition?

70S ribosome; 50S and 30S subunits.

What is the general fluid interior of the bacterial cell called that contains no organelles?

Cytosol.

Differentiate autotrophs and heterotrophs in terms of carbon source.

Autotrophs use inorganic carbon (CO2); heterotrophs use organic carbon.

What is the difference between phototrophs and chemotrophs?

Phototrophs use light as an energy source; chemotrophs obtain energy from chemical compounds.

What are the main categories of temperature-based bacterial groups?

Psychrophilic (10-20°C), Mesophilic (20-40°C), Thermophilic (50-125°C).

What is capnophilic growth?

Organisms that require elevated CO2 for growth.

Which growth temperature ranges are typical for lab incubation of aerobes and anaerobes?

Aerobes: 35-37°C; Anaerobes: 35-37°C; fungi: 28-30°C; many bacteria incubated 24-48h.

What is a neutrophilic bacterium?

Organisms that require neutral pH for growth (around pH 7).

What is acidophilic growth?

Organisms requiring acidic pH for growth (low pH).

What is halophilic growth?

Organisms requiring high salt concentrations to grow.

Which medium and test are used to assess salt tolerance in Enterococci?

Salt tolerance test; growth on Mannitol Salt Agar (MSA) for Staphylococcus; Enterococci show growth.

What is the candle jar method used for in culture?

Creating a microaerophilic atmosphere with reduced oxygen and increased CO2; approximately 5% O2, 10% CO2, 85% N2.

What is the purpose of moisture in culture and what humidity level is mentioned?

Prevent drying; approximately 70% moisture for survival of organisms.

What are the major phases of bacterial growth and their characteristics?

Lag phase (no division, adaptation); Log/exponential phase (rapid growth); Stationary phase (growth equals death); Death phase (death exceeds growth).

What is conjugation in bacterial genetics?

DNA transfer between bacteria via the sex pilus forming a conjugative bridge.

What is transduction in bacterial genetics?

DNA transfer mediated by bacteriophages (phages) infecting bacteria.

What is transformation in bacterial genetics?

Uptake of free DNA by a competent recipient cell from the environment.

What are the risk levels described for individual and community risk in biosafety context?

No/low risk; Moderate individual risk; Low community risk; High individual risk; High community risk (risk matrix shown in notes).

What are the four basic biosafety levels and their general protections?

BSL-1: standard practices; BSL-2: PPE; BSL-3: negative pressure, specialized PPE; BSL-4: full-body suit with independent ventilation.

What are the three main classes of Biological Safety Cabinets (BSC) and their protections?

Class I: protects personnel; Class II: protects personnel and work surface; Class III: full enclosure with gloves, protects personnel and environment.

What agents fall under Category A of bioterrorism agents and give examples?

Great public health threat; examples include Bacillus anthracis, Francisella tularensis, variola (smallpox), Ebola, etc.

What agents fall under Category B and Category C in bioterrorism risk?

Category B: moderate morbidity and low mortality (easily transmitted); Category C: emerging pathogens with potential for mass dissemination.

What is sterilization and how does it differ from disinfection?

Sterilization: complete destruction/removal of all forms of microbial life including spores; Disinfection: destruction/removal of pathogens but not necessarily all microorganisms or spores.

Name physical methods of sterilization.

Moist heat (autoclaving), dry heat, filtration, exposure to ionizing radiation.

Name chemical methods of sterilization.

Ethylene oxide; formaldehyde vapor; hydrogen peroxide vapor; glutaraldehyde; peracetic acid.

Name chemical methods of disinfection.

Alcohols, iodophors, chlorhexidine, hexachlorophene, phenolics, quaternary ammonium compounds (quats), heavy metals, halogens, 10% hydrogen peroxide; aldehydes.

What does pasteurization accomplish?

Destruction of certain pathogens and reducing microbial load, without sterilization; used for foods and drinks.

Which two components are essential for the lance of the protective functions of capsules?

Capsule prevents phagocytosis; capsule swelling detectable by serotyping and Quellung reaction.

Which organism’s capsule swelling is used as indication of encapsulation by serotyping?

Klebsiella (through Quellung reaction).

What is the role of teichoic acid in Gram-positive bacteria?

Teichoic acids are present in Gram-positive cell walls and contribute to filamentous structure and antigenicity; absent in Gram-negative walls.

Which organism features a spirochete with axial filaments enabling motility?

Spirochetes use axial filaments (periplasmic flagella) for motility.

What is the function of the bacterial endospore and which organism groups form them?

Survival in harsh conditions; formed by Bacillus and Clostridium species.

What is the main function of the bacterial ribosome and its size class?

Protein synthesis; 70S ribosome (composed of 50S and 30S subunits).