Bacteria and Eucaryotic Pathogens

Question 1

Bacterial cell wall of gram (+) and gram (-) Bacteria:

Answer 1

(-)
outer plasma membrane with LPS
Periplasmic space
Peptidoglycan layer 2-8 nm (murein)
inner plasma membrane

(+)
Thick Peptidoglycan layer 20-80 nm with Teichoic acid
Inner plasma membrane

Question 2

What are the factors used to characterize bacterial species?

Answer 2

Shape, staining pattern (gram +, gram -), Biochemistry, Physiology (growth and metabolism), genetics

Question 3

Tree of bacteria: Proteobacteria

Answer 3

Gram-negative
Beneficial and pathogenic
Five groups: alpha, ß, gamma, delta, epsilon

Question 4

Proteobacteria -> Gammaproteobacteria

Answer 4

most diverse group, mostly gram negative
-Pseudomonas aeruginosa
-Haemophilus influenzae
-Vibrio cholera
-Legionella pneumophila
-Enterobacteriaceae (E coli, Salmonella)

Question 5

Gram Negative Pathogens (life cycle with spores)

Answer 5

Chlamydia trachomatis
-Eye infection, STI
-Obligate intracellular bacterium (require eukaryotic host to survive)

Question 6

Gram Negative Pathogens: Spirochetes

Answer 6

Treponema pallidum (syphilis)
Borrelia burgdorferi (Lyme disease)

-long spiral-shaped with axial filament (flagellum) for movement

Question 7

Gram-Negative Pathogens: CFB Group

Answer 7

Cytophaga, Fusobacterium, and Bacteroides (human gut)
anaerobic, fermenters (use substrate-level phosphorylation)

Question 8

What are two large gram-positive bacteria groups, and how are differentiated?

Answer 8

Actinobacteria (high GC Gram +)
Firmicutes (low GC Gram -)
both include pathogens and microbiota species

Question 9

Characteristics of Actinobacteria:

Answer 9

Mycobacterium (M. tuberculosis), Corynebacterium (C. diphtheria)
Bifidobacterium (commensal, probiotic)

aerobic, variety of cell walls

Question 10

Examples of Firmicutes: Clostridia

Answer 10

Clostridia:
-gram + and spore-forming
-hospital pathogen, found in soil
-make toxins
-> Clostridium tetani, Clostridium botulinum

Question 11

Examples of Firmicutes: Lactobacillales

Answer 11

includes cocci (round) and bacilli (long-shaped)
-> Streptococcus
some are beneficial Lactobacillus acidophilus (yogurt and cheese)
and some are pathogenic

Question 12

Similarities between Archaea and Bacteria; Archea and Eukaryotes

Answer 12

Bacteria:
No organelles, unicellular, usually 1 chromosome, binary fission (asexual), small cell size, DNA stored in the cytoplasm

Eukaryotes:
Genetics structure: some Introns, some histones, complex genome
insensitive to antibiotics, multiple RNA polymerases, similar ribosomes

Question 13

Bacterial characteristics beneficial for self-differentiation:

Answer 13

-Phosphatidylglycerol (lipid membrane): in all bacteria / humans have a lot
-Polysaccharide: in some bacteria / can also be found in human
-Lipopolysaccharide: in some bacteria / ….
-ds DNA: in all bacteria / easy to differentiate when found in cytoplasm
-Hexokinase: in most bacteria / amino acid seq. different in human different -> innate cant differentiate, adaptive can
-mRNA: n all bacteria; is not beneficial for differentiation
-Salmonella Typhi exopolysaccharide: ….

Question 14

What are the 4 kingdoms of eukaryotes?

Answer 14

Animals, Fungi, Plants, Protists

Question 15

What are examples of Protists?

Answer 15

-Amoeboid Protozoans
-Spore-Forming Protozoans (Apicomplexa)
-> Taxoplosmosis in cat litter, Malaria
->complex life cycle, asexual and sexual
-Flagellated Protozoans- free living (Euglena), parasitic (Trichomonas vaginalis)

Question 16

What are the characteristics of Fungal Diseases?

Answer 16

-Disease caused by fungi is called mycoses
Mostly in Immunocompromised individuals

-but also they are also true pathogens, f.e. Histoplasmosis,
Histoplasmosis grows in soil and the spores are inhaled

-some can produce mycotoxins and cause allergies (Claviceps purpurea)

Question 17

What are examples and characteristics of Parasites?

Answer 17

-Helminths: parasitic worms (flat or round (nematodes)
-complex life cycle, sexual reproduction
-spread in microscopic form -> Eggs ingested via fecal-oral route

Question 18

What are the cellular targets of antimicrobial drugs?

Answer 18

-Plasma membrane -> polymyxin targets LPS -> cause destabilization and cell lysis

-prokaryotic ribosomes - Chloramphenicol 50S, Aminoglycosides 30S, Tetracyclines 30 S

-metabolic pathways - Sulfonamides inhibits folic acid production, Isoniazid prevents synthesis of mycolic acid

-DNA/RNA synthesis -> Rifamycin bacterial RNA polymerase
-cell wall (peptidase blocked)

Question 19

Which type of drugs may cause side effects and why?

Answer 19

Drugs targeting Fungi and Protists, bc they are more similar to human than bacteria are

Question 20

What different steps of infection can antivirals block?

Answer 20

Attachment
Penetration
Uncoating
Replication and assembly
Release

Question 21

What agents are used by antivirals?

Answer 21

-Nucleotide analogs -> also target human system (limited time use)

-other immune components: Human rabies immunoglobin
(HRIG), interferon-alpha (cytokine shutting down protein synthesis of infected cells)

Question 22

What substance is found in fungi but not in humans and what antifungal agents?

Answer 22

A sterol called ergosterol in the fungal cell membrane

Anti-fungal drugs:
* Azoles (imidazoles and triazoles)
* Allyamines
* Polyenes

Question 23

What are drugs inhibiting cell wall synthesis of fungi?

Answer 23

Echinocandin drugs: target the enzyme making beta-glucan

Polyoxins and nikkomycins: target chitin synthesis

Question 24

Why is it difficult to develop antiprotozoal and
antihelminthic drugs?

Answer 24

-These parasites are eukaryotes, components are closer to human, and bc of complex life cycles

-All antimicrobials have increasing resistance issues

Question 25

LO: Protozoa

Answer 25

x)Amoeboid Protozoans
-free-living and pathogenic
x)Spore-Forming Protozoans (Apicomplexa)
-mostly obligate intracellular
-complex life cycles: sexual and asexual stages
-Toxoplasmosis, Malaria,

x)Flagellated Protozoans
-free-living, and parasitic

Question 26

LO: Fungal

Answer 26

Spore-forming: Histoplasma
-from fetes to the lungs of humans (lung disease: histoplasmosis)

Mycotoxin producing: Claviceps purpurea

Question 27

LO: Animals -> Helminths

Answer 27

Parasitic worms
-Sexual reproduction
-Usually spread in a microscopic form -> Eggs ingested via fecal-oral route