Bacteriology: The Basics Flashcards
Name 2 reasons that bacteria infections are on the rise
- Advancements in medicine have created large populations of immunocompromised people (elderly, chemotherapy patients, HIV-infected individuals, transplant recipients)
- The increasing spread of antibiotic resistant bacteria, facilitated by international travel and the misuse of available antibiotics
* Main cause of mortality during human evolution has been infectious disease, up until the 20th century.
How can relationships among Bacteria be surmised?
By comparing 16S rRNA sequences
Name and describe the different shapes of bacteria
- COCCI: spherical, singular is coccus
- BACILLI: Rods (Short bacilli are called coccobacilli). Singular is bacillus
- SPIRAL FORMS: comma shaped, S-shaped, spiral-shaped
- PLEOMORPHIC: lacking a distinct shape
What is Diplococci, Streptococci, Tetrad, Sarcinae, and Staphylococci? Give examples of each
- DIPLOCOCCI:
- two cocci together
- Neisseria sp, Moraxella catarrhalis
- STREPTOCOCCI:
- Chain of cocci
- Streptococci sp
- TETRAD:
- 4 cocci together forming a square
- Micrococcus luteus; soil, skin
- SARCINAE:
- cocci together forming a cube
- Sacina sp; skin, intestines
- STAPHYLOCOCCI:
- Clusters of Cocci
- Staphylococcus aureus
Give examples of single bacillus, Diplobacilli, streptobacilli, Coccobacilus
- SINGLE BACILLUS and DIPLOBACILLI:
- Bacillus sp
- Escherichia sp
- Mycobacterium sp
- Salmonella sp
- Klebsiella sp
- Pseudomonas sp
- Yersinia sp
- Porphyromonas gingivalis
- STREPTOBACILLI:
- Bacillus anthracis
- Bacillus megaterium; ubiquitous in the environment
- COCCOBACILLUS:
- Haemophilus Influlenzae
- Chlamydia trachomatis
- Bordetella pertussis (whooping cough agent)
Give examples of Vibrio, Spirilium, and Spirochetes
- VIBRIO:
- Vibrio Cholerae
- SPIRILIUM
- Spirillum sp; rat bite fever (sudoku) agent
- SPIROCHETE:
- Borellia
- Brachyspira
- Treponemonas
- Leptospira
- Lyme disease, relapsing fever, syphilis, leptospirosis
What are the key unique features of bacteria?
- Usually single, circular chromosome (haploid, no histones)
- May have plasmids
- No internal organelles, no nucleus
- Cell wall components
- 70S ribosomes
- Unique metabolic pathways
- Mode of replication (binary fission)
Why are unique features of bacteria important to our immune system?
They provide the basis for recognition by innate and adaptive immunity and for antibiotic-based therapies
How to Bacteria Replicate?
Binary Fission
What limits Bacterial growth?
- Availability of nutrients from the environment and competition from other bacteria
- If they are in a host they will face other limitations such as immune/ defense systems of the host
Bacteria are often associated with ________
Biofilms
**free swimming bacteria are called planktonic
What makes up Extra cellular matrix in a biofilm?
Polysaccharides, DNA, Proteins
Where can biofilms form?
- In the environment: Legionella Pneumophila forms biofilms within air conditioning towers
- On Medical devices: catheters, valve implants, replacement joints
- On body surfaces: lungs of cystic fibrosis patients, burned tissue, wounds, guns and teeth (dental plaque)
What does it mean for bacteria to be refractory to antibiotic treatment?
Resistant to antibiotics
What is quorum sensing?
- What regulates biofilm
2. system of stimuli and response correlated to population density
What are bacteria with no cell wall called?
Mycoplasma
T/F Once a bacteria is in a biofilm that is where it stays for the duration of its life.
FALSE: bacteria within bioflims can persist for long periods, but can break off to cause systemic or distant infecions
Name basic components of Gram + and Gram - cell walls
GRAM +
-Thick peptidoglycan layer outside the plasma membrane
GRAM -
- Thinner peptidoglycan layer covering plasma membrane
- Existence of a outer membrane
- Existence of periplasmic space
Give 2 examples of acid fast bacteria
- Mycobacteria
2. Nocardia
What is the purpose for bacterial cell walls?
-Maintains cell shape, controls influx and efflux of materials, protects against osmotic lysis
Bacterial cell walls are the site for what?
- Respiratory chains
- Secretion systems
- Adhesins
What targets the bacterial cell wall?
Lysozyme and many antibiotics
What are cell walls the basis for?
Stereotyping pathogens
Antigens: O (LPS), K (Capsule), H (flagellin)
Bacteriall cell walls contain _________ that are recognized by _______
- Ligands
2. Innate and adaptive immune systems
In more detail what are the components of a Gram + cell wall?
Thick peptidoglycan layer interspersed with Teichoic acid and Lipoteichoic acid.
What is teichoic acid?
Polymers of either glycerol phosphate or ribitol phosphate with various sugars, amino acids, and amino sugars as substituents
- they help anchor wall to membrane
How can peptidoglycan stimulate inflammatory responses?
Binding of it by the Pattern Recognition Receptor (PRR) Toll-like Receptor 2 (TLR2)
Loss of cell wall in gram + leads to what?
Production of Protoplasts (L-form bacteria)
Biosynthesis of Peptidoglycan structure is inhibited by what?
Various antibiotics including beta-lactams like penicillin
What cleaves peptidoglycan structure?
Lysozyme
In more detail, what makes up Gram - cell wall and how does it differ from gram positive?
- Has a thinner peptidoglycan layer and a periplasmic space.
- Has an outer membrane often associated with Porins
- Contains LPS
How can LPS stimulate inflammatory responses?
Binding of it by PRR Toll-like Receptor 4
Bacteria with no cell wall are linked to what diseases?
- Pelvic inflammatory disease
- Pneumoniae
- Meningitis (perinatal)
- Abortions
- Urethritis
- Infertility
- Premature birth
- some cancers
In addition to mycoplasama, what other bacteria have no cell wall?
Ureaplasma
What is required by bacteria with no cell wall to stabilize the membrane?
Sterols (like cholesterol from the hose)
Name some other factors associated with cell walls
- Electron transport chains (aerobic bacteria and facultative anaerobes versus anaerobes)
- Protein secretion systems (General, Types I-VII)
- Flagella
- Adhesisns (Fimbrial and afimbrial
- Capsules
- Spores
Describe energy production routes of bacteria
- PHOTOTROPHS: Use light to generate energy
- AUTOTROPHS: use chemicals to generate energy (ammonium and sulfide for example)
- HETEROTROPHS: Use organic (carbon) sources
- CHEMOHETEROTROPHS: most medically important bacteria
- FERMENTATION: used by many bacteria to breakdown glucose to pyruvate, creating ATP
Chart slide 25
Memorize this but don’t make it a huge priority
Describe Gram - secretion systems
Type I, II, V secretion systems deliver proteins like toxins, siderophores to the extracellular environment
Type III, IV, VI, VII secretion systems can inject factors (effectors proteins or toxins) directly into target host cells
Describe bacterial flagella
Promote bacteria dissemination within host environments, and facilitate chemotaxis towards or away from specific stimuli
How can bacteria manipulate flagella to escape immune detection and responses?
- Some bacteria can swap different flagella
2. Expression of flagella is frequently down regulated within a host to avoid triggering immune response
What are the different forms of flagella
- Peritrichous
- Monotrichous and polar
- Lophotrichous and polar
- Amphitrichous and polar
What are axial filaments?
- Flagella present with the periplasmic space
2. Similar to flagella except they wrap around the cell
What cells move by way of axial filaments?
Spirochetes
What is another name for axial filaments?
Endoflagellum
What are bacterial adhesins and what are they associated with?
- cell-surface components or appendages of bacteria that facilitate adhesion or adherence to other cells or to surfaces. Adhesins are a type of virulence factor.
- Often associated with hairlike fibers called pili or fimbriae, can have unique receptor specificites
- Can act as receptors for phage, promote conjugation (genetic exchange), and mediate biofilm formation
What is tissue tropism?
the cells and tissues of a host which support growth of a particular virus or bacteria. Some bacteria and viruses have a broad tissue tropism and can infect many types of cells and tissues.
Slide 36
May have examples worth committing to memory
What are Type IV pili implicated in?
- Conjugation (bacterial Mating)
- DNA binding/uptake (competence)
- Motility
What are capsules and what do they do?
- Layers of polysaccharide (or polypeptide associated with the bacterial surface
- Provides protection against desiccation, phage, detergents, antimicrobial peptides
- Protects bacteria from phagocytes (neutrophils and mactrophages)
What is the relationship between antibodies and capsules?
Antibodies against specific capsule (K antigen) are opsonic, and for this reason capsular antigens area main component in some vaccines
