Microbiology Flashcards
What is endospores?
Dormant highly resistant bodies formed by some bacteria in adverse environmental conditions
Produced inside bacterial cell
Resistance of endospores is due to…?
Layered structure Dehydrated state Low metabolic activity High levels of small acid-solubleproteins High content of dipicolinic acid
How is endospores produced?
DNA replication
Cytoplasmic membrane invaginates creating forespore=first membrane
Cytoplasmic membrane engulfs forespore=second membrane
Calcium and dipicolinic add deposited btw membranes
Maturation=completion of spore coat
Release
Function of capsule?
Protection
Increase adherence
Antiphagocytic
Antigenic
Function of cell wall?
Layer of Peptidoglycans Protects from mechanical damage Protects from osmotic lysis Influence pathogenicity Influence staining propertiesq
Cell wall in gram+ Bacteria
Thick layer of pepridoglycans
No outer membrane
Stains blue
Cell wall in gram- bacteria
Thin layer of peptidoglycans
Outer membrane with lipopolysaccharides (endotoxic)
Stains pink
Cell Wall in mycoplasms
No cell wall only membrane
Flagella
“Tail” of protein confers motility
Pili
Protein covering cell body
On gram- bacteria
For attachment or conjugation
Monotrichous flagella
One flagella
Lophotrichous flagella
Several flagella on one end
Amphitrichous flagella
One flagella in each end
Peritrichous flagella
Flagella all over
Curve of bacterial growth
Lag phase-no initial growth, constant number
Exponential growth-high growth, number increases
Stationary phase-constant number
Decline phase-growth decreases, numbers decreases
Mesophiles
Grow in body temperature
Psychrophiles
Grow in cold temperatures
Termophiles
Grow in warm temperatures
Aerobes
Needs oxygen
Capnophiles
Needs CO2
Anaerobes
Needs no oxygen
Facultative anaerobes
Can grow both with/without oxygen
Microaerophils
Requires low amount of oxygen
Preservation of microorganisms
Cryovials-freezing in liquid nitrogen
Lyophilization-freeze drying
Active culture- kept alive providing nutrients etc
Endogenous infections
From inside body Damaged epithelial barriers Weakened immune system Microbial imbalance Access to where normally not present
Exogenous infections
From outside body Ingestion Inhalation Infusion/transplant Sexual Congenital
Stages of infectious disease
Host infection
Colonization and growth
Dissemination of pathogens in host
Tissue damage
Colonization strategies
Iron-chelating compounds (taking iron from transferrin/lactoferrin)
Erythrocyte lysis (taking iron from Hb)
Must tolerate micro environmental conditions
Avoid immune system
Exotoxins
Produced by live bacteria, both gram+ and - Proteins Heat labile Potent toxins Not pyrogenic Highly antigenic Extrachromosomally determined synthesis
Endotoxins
Component of cell wall in gram- bacteria Lipopolysaccharide Heat stable Moderate non-specific toxins Pyrogenic Not antigenic Encoded in chromosome
Acute infection
Short severe clinical course
Cleared from body (or death)
Chronic infection
Host fails to eliminate pathogen
Persistent shedding
Long lasting/ongoing
Latent infection
Presence of pathogen without shedding
What is an antibiotic?
Microbial metabolites that kill or inhibit growth of bacteria
Bactericidal-kills
Bacteriostatic-inhibit growth
What is an antimicrobial agent?
Includes both antibiotics and synthetic compounds with antimicrobial activity
