CH 6 BACTERIA Flashcards
What class of cells are bacteria under?
Prokaryotes
What are 2 domains of bacteria?
Archaebacteria and eubacteria
What are three structures found in the cytoplasm of prokaryotic cells?
Nucleoid, ribosomes, organelle-like structures
What compound makes up the bacterial cell wall?
Peptidoglycans
What is unique about the prokaryotic cell wall?
Resists osmotic pressure changes
What are 2 kinds of hair-like projections that allow bacteria to adhere to surfaces?
Fimbriae and pili
What bacterial structure protects from phagocytosis?
Glycocalyx
Why are unique bacterial structures significant to medicine?
They are the targets of certain drugs
What process do bacteria use to reproduce?
Binary fission
What bacterial structures contain genes that are capable of being transmitted to other bacterial cells?
Plasmids
What is the term for particles produced by some bacteria under harsh conditions?
Endospores
What do endospores germinate into under favourable conditions?
Vegetative bacterial cells
What are 6 ways of identifying and classifying species of bacteria?
- Growth rate
- Nutritional requirements
- Staining
- Shape
- Pathogenicity
- Antibiotic resistance
What are 2 ways bacteria resist phagocytosis?
- Producing enzymes and toxins
- Taking refuge in host cells
What are 2 classes of bacterial toxins?
Proteins and lipopolysaccharides
True or false: Bacterial toxins always act at the site of bacterial proliferation
False
Secreted exotoxins are usually what complex molecule?
Proteins
Endotoxins are usually what complex molecule?
Lipopolysaccharides
How do toxins benefit bacteria?
Promote their growth and invasion into tissues.
What gram positive cocci resemble a cluster of grapes?
Staphylococci
What disease caused by s. aureus results in a 50% mortality?
Pneumonia
Name 4 toxins produced by s. aureus
- coagulase
- hemolysin
- exfoliatin B
- beta lactamase
What are the effects of exfoliatin B?
Separation of skin layers
What are the effects of beta lactamase?
Hydrolyzes penecillin
What are 3 syndromes associated with s. aureus?
- Scalded skin syndrome
- Toxic shock syndrome
- Food poisoning
What staphylococcus is normal human flora and causes nosocomial infections?
S. epidermidis
What gram positive cocci resemble bead-like chains?
Streptococci
Which streptococci cause strep throat?
S. pyogenes, group C & G
If strep throat is left untreated, what will result?
Rheumatic fever, glomerulonephritis
What 2 toxins are produced by s. pyogenes?
Hemolysin, pyrogenic toxin
Which type of streptococcus colonizes the GI and GU tracts, and can be lethal to newborns?
Group B
Which streptococcus is a leading cause of pneumonia?
S. pneumoniae / pneumococcus
Which gram negative coccus causes urethritis and pelvic inflammatory disease?
Neisseria gonorrheae
If PID is left untreated, what will result?
Obstruction to salpinx, infertility
Which gram negative coccus causes epidemic meningitis?
Neisseria meningitidis
Which gram positive rod causes diphtheria?
Corynebacteria diphtheria
Diphtheria toxin has what effects?
Protein synthesis inhibition, development of pseudomembrane
How is diphtheria transmitted?
Respiratory aerosol
Which gram positive rod causes anthrax?
Bacillus anthracis
Name 3 kinds of anthrax
- Cutaneous
- Gastrointestinal
- Pulmonary
Why is bacillus anthracis so resilient?
Endospores in soil are resistant to environmental factors.
What does anthrax toxin cause?
Cytokine secretion
Which gram positive rod causes myonecrosis and gas gangrene?
Clostridium perfringens
What may precede a c. perfringens infection?
Septic abortion, crushing injury, compound fracture, gunshot/knife wounds, malignancy
Which gram positive rod causes food poisoning and flaccid paralysis?
Clostridium botulinum
What is the action of c. botulinum toxin?
Inhibits ACH at neuromuscular junction
What is a therapeutic use for c. botulinum toxin?
Botox
Which gram positive rod causes tetanus?
Clostridium tetani
What toxin does c. tetani produce?
Tetanospasmin
What is the action of tetanospasmin?
Inhibits release of glycine and GABA, causing rigid paralysis
Where can c. tetani be found?
In soil and GI tract
Which gram negative rod is a common opportunistic infection, and can be identified by a grapey odor and fluorescent blue-green colour?
Pseudomonas aeriginosa
What gram negative rod is normally found in the GI tract?
Escherichia coli
What toxin is produced by the 0157:H7 strain of e. coli, and what are its effects?
Shiga toxin, diarrhea
What are possible consequences of e. coli infection?
Hemolytic uremic syndrome, acute kidney failure
Which gram negative rod causes typhoid?
Salmonella enterica
How is s. enterica transmitted?
Fecal-oral
What are common effects of s. enterica infection?
Attacks liver, causes diarrhea
What gram negative rod causes undulating fever in humans, and is common to people who work with animals?
Brucella
What gram negative rod causes whooping cough?
Bordetella pertussis
What is the action of pertussis toxin?
Inhibits adenylyl cyclase to reduce phagocytosis
What gram negative rod causes plague?
Yersinia pestis
What site does y. pestis colonize?
Lymph nodes
Which gram negative rods are characterized by helical shape and propelling filaments?
Spirochetes
Name 3 examples of spirochetes
- Leptospiro spp
- Borrelia burgdorferi
- Treponema pallidum
What unique features are of interest in identifying acid fast bacteria?
- Mycolic acid in cell wall makes staining difficult
- Slow cell division makes culture growth difficult
What other advantage does mycolic acid give acid fast bacteria?
Resist phagocytosis
What acid fast bacteria causes tuberculosis?
Mycobacterium tuberculosis
Name 4 kinds of TB
- Primary TB
- Secondary TB
- Pulmonary TB
- Disseminated/miliary TB
Why are many cases of TB latent?
After phagocytosis, bacteria survive
What 2 symptoms characterize primary TB?
Granulomata, caseous necrosis
What characterizes secondary TB?
Severe respiratory complications
What appearance characterizes disseminated/miliary TB?
Grain like appearance on x-ray
Which bacteria causes leprosy/Hansen’s disease?
Mycobacterium leprae
What are some early symptoms of leprosy?
Loss of sensation, macules, papules
What is unique about the transmission of m. leprae?
Requires repeated contact
What is unique about the incubation of m. leprae?
Long period–3-5 years
What bacteria causes cholera?
Vibrio cholerae
What is the action and effect of cholera toxin?
Activates adenylyl cyclase–promotes intestinal secretion of fluid and electrolytes causing diarrhea