Microbiology- Basic Bacteriology

Question 1

Pilus/fimbria

Answer 1

Mediate adherence of bacteria to cell surface;

sex pilus forms during conjugation.

Question 2

Spore

Answer 2

Gram ⊕ only.

Survival: resist dehydration, heat, chemicals.

Question 3

Capsule

Answer 3

Protects against phagocytosis

Question 4

Outer membrane

Answer 4

Gram ⊝ only.
Endotoxin: lipid A induces TNF and IL-1; antigenic O polysaccharide component.
Most OMPs are antigenic.
Porins: transport across outer membrane.

Question 5

Cytoplasmic

membrane

Answer 5

Phospholipid bilayer sac with embedded
proteins and other enzymes.

Lipoteichoic acids (gram ⊕ only) extend from membrane to exterior.

PBPs involved in cell wall synthesis

Question 6

Gram ⊕ examples: Spherical (coccus)

Answer 6

Staphylococcus (clusters)
Streptococcus (chains or pairs)
Enterococcus (pairs or short chains)

Question 7

Gram ⊝ examples: Spherical (coccus)

Answer 7

Moraxella catarrhalis

Neisseria

Question 8

Gram ⊕ examples: Rod (bacillus) Bacillus

Answer 8

Clostridium
Corynebacterium
Gardnerella (gram variable)
Lactobacillus
Listeria
Mycobacterium (acid fast)
Cutibacterium (formerly Propionibacterium)

Question 9

Gram ⊝ examples: Respiratory Rod (bacillus) Bacillus

Answer 9

ƒƒ Acinetobacter baumannii
ƒƒ Bordetella
ƒƒ Burkholderia cepacia
ƒƒHaemophilus (pleomorphic)
ƒƒ Legionella (silver stain)

Question 10

Gram ⊝ examples: Enteric Rod (bacillus) Bacillus

Answer 10

ƒƒ Bacteroides
ƒƒ Campylobacter
ƒƒ E coli
ƒƒ Enterobacter
ƒƒ Fusobacterium
ƒƒHelicobacter
ƒƒ Klebsiella
ƒƒ Proteus
ƒƒ Pseudomonas
ƒƒ Salmonella
ƒƒ Serratia
ƒƒ Shigella
ƒƒ Vibrio
ƒƒ Yersinia

Question 11

Gram ⊝ examples: Zoonotic Rod (bacillus) Bacillus

Answer 11

ƒƒ Bartonella
ƒƒ Brucella
ƒƒ Francisella
ƒƒ Pasteurella

Question 12

Gram ⊕ examples: Branching filamentous

Answer 12

Actinomyces

Nocardia (weakly acid fast)

Question 13

Gram ⊝ examples: Pleomorphic (no cell wall)

Answer 13

Anaplasma, Ehrlichia
Chlamydiae (Giemsa)
Rickettsiae (Giemsa)
Mycoplasma (contains sterols, which do not Gram stain), Ureaplasma

Question 14

Gram ⊝ examples: Spiral Spirochetes:

Answer 14

ƒƒ Borrelia (Giemsa)
ƒƒ Leptospira
ƒƒ Treponema

Question 15

Cell wall

Answer 15

Peptidoglycan is a sugar backbone with peptide side chains cross-linked by transpeptidase

Gram + : thick
Gram - : Thin

Question 16

Wich bacterias dont stain well with gram

Answer 16

“These Little Microbes May Unfortunately Lack Real Color But Are Everywhere”

• Treponema, Leptospira: Too thin to be visualized.
• Mycobacteria Cell wall has high lipid content.
• Mycoplasma, Ureaplasma No cell wall.
• Legionella, Rickettsia, Chlamydia, Bartonella, Anaplasma, Ehrlichia Primarily intracellular; also, Chlamydia lack classic peptidoglycan because of lowmuramic acid.

Question 17

Giemsa stain

Answer 17

RICKiy got CHLAMYDIA as he TRIed to Please the
BORed “Geisha.”

Rickettsia, Chlamydia, Trypanosomes , Plasmodium, Borrelia

Question 18

Periodic acid–Schiff stain

Answer 18

used to diagnose Whipple disease (Tropheryma

whipplei)

Question 19

Ziehl-Neelsen stain

carbol fuchsin

Answer 19

Acid-fast bacteria (eg, Mycobacteria C , Nocardia; stains mycolic acid in cell wall); protozoa (eg, Cryptosporidium oocysts).

*Auramine-rhodamine stain is more often used for screening (inexpensive, more sensitive).

Question 20

India ink stain

Answer 20

Cryptococcus neoformans

Question 21

Silver stain

Answer 21

Fungi (eg, Coccidioides E , Pneumocystis jirovecii), Legionella, Helicobacter pylori

Question 22

Fluorescent antibody stain

Answer 22

Used to identify many bacteria and viruses. Example is FTA-ABS for syphilis

Question 23

Special culture requirements: H influenzae

Media used and content

Answer 23

Chocolate agar 
Factors V (NAD+) and X (hematin)

Question 24

Special culture requirements: N gonorrhoeae, N meningitidis

Media used and content

Answer 24

Thayer-Martin agar

“Very Typically Cultures Neisseria”: Vancomicina, Trimpethoprim, Colistin, Nistatin

Question 25

Special culture requirements: B pertussis Media used and content

Answer 25

Bordet-Gengou agar (Bordet for Bordetella) - Potato extract Regan-Lowe medium - Charcoal, blood, and antibiotic

Question 26

Special culture requirements: M pneumoniae Media used and content

Answer 26

Eaton agar | Requires cholesterol

Question 27

Special culture requirements: M tuberculosis

Answer 27

Löwenstein-Jensen agar

Question 28

Special culture requirements: C diphtheriae

Answer 28

Tellurite agar, Löffler medium

Question 29

Special culture requirements: Lactose-fermentin enterics

Answer 29

MacConkey agar Fermentation produces acid, causing colonies to turn pink

Question 30

Special culture requirements:

Answer 30

Fungi Sabouraud agar “Sab’s a fun guy!”

Question 31

Special culture requirements: E coli

Answer 31

Eosin–methylene blue (EMB) agar Colonies with green metallic sheen

Question 32

Anaerobes Examples

Answer 32

"Can’t Breathe Fresh Air" Clostridium, Bacteroides, Fusobacterium, and Actinomyces israelii.

Question 33

Facultative anaerobes Examples

Answer 33

Streptococci, staphylococci, and enteric gram ⊝ bacteria.

Question 34

Facultative intracellular bugs

Answer 34

"Some Nasty Bugs May Live FacultativeLY" Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis

Question 35

Obligate intracellular bugs

Answer 35

Stay inside (cells) when it is "Really CHilly and COld". Rickettsia, CHlamydia, COxiella

Question 36

Encapsulated bacteria

Answer 36

"Please SHiNE my SKiS"

Question 37

Asplenics need vaccines to protect against:

Answer 37

(No Spleen Here) ƒƒN meningitidis ƒƒ S pneumoniae ƒƒH influenzae

Question 38

Encapsulated bacteria vaccines

Answer 38

Pneumococcal vaccines: PCV13 (pneumococcal conjugate vaccine), PPSV23 (pneumococcal polysaccharide vaccine with no conjugated protein) H influenzae type b (conjugate vaccine) Meningococcal vaccine (conjugate vaccine)

Question 39

Urease-positive organism

Answer 39

"Pee CHUNKSS" Proteus, Cryptococcus, H pylori, Ureaplasma, Nocardia, Klebsiella, S epidermidis, S saprophyticus

Question 40

Pigment-producing bacteria

Answer 40

Actinomyces israelii—yellow “sulfur” granules S aureus—yellow pigment P aeruginosa—blue-green pigment (pyocyanin and pyoverdin). Serratia marcescens—red pigment.

Question 41

In vivo biofilmproducing bacteria

Answer 41

S epidermidis, Viridans streptococci, P aeruginosa, Nontypeable (unencapsulated) H influenzae

Question 42

Bacterial virulence factors

Answer 42

Protein A Binds Fc region of IgG. (S. auerus) IgA protease Enzyme that cleaves IgA (No Spleen Here) M protein Helps prevent phagocytosis, by Group A streptococci, Reumatic fever.

Question 43

Type III secretion system (injectismoe)

Answer 43

Needle-like protein appendage facilitating direct delivery of toxins from certain gram ⊝ bacteria (eg, Pseudomonas, Salmonella, Shigella, E coli)

Question 44

Bacterial genetics: Transformation

Answer 44

Competent bacteria can bind and import short pieces of environmental naked bacterial chromosomal DNA. (No Spleen Here)

Question 45

Bacterial genetics: Conjugation F+ × F–

Answer 45

``` F+ plasmid contains genes required for sex pilus and conjugation. Bacteria without this plasmid are termed F–. Sex pilus on F+ bacterium contacts F− bacterium. A single strand of plasmid DNA is transferred across the conjugal bridge (“mating bridge”). ```

Question 46

Bacterial genetics: Conjugation Hfr × F–

Answer 46

F+ plasmid can become incorporated into bacterial chromosomal DNA, termed highfrequency recombination (Hfr) cell.

Question 47

Bacterial genetics :Transduction (Generalized)

Answer 47

A packaging “error.” Lytic phage infects bacterium, leading to cleavage of bacterialDNA. Parts of bacterial chromosomal DNAmay become packaged in phage capsid. Phage infects another bacterium, transferring these genes.

Question 48

Bacterial genetics :Transduction (Specialized)

Answer 48

Lysogenic phage infectscbacterium; viral DNA incorporates into bacterial chromosome. When phage DNA is excised, flanking bacterial genes may be excised with it. DNA is packaged into phage capsid and can infect another bacterium.

Question 49

5 bacterial toxins are encoded in a lysogenic phage

Answer 49

(ABCD’S): Group A strep erythrogenic toxin, Botulinum toxin, Cholera toxin, Diphtheria toxin, Shiga toxin.

Question 50

Bacterial genetics: Transposition

Answer 50

Segment of DNA (eg, transposon) that can “jump” (copy/excise and reinsert) from one location to another, can transfer genes from plasmid to chromosome and vice versa. critical process in creating plasmids with multiple antibiotic resistance

Question 51

Spore-forming bacteria

Answer 51

``` Bacillus anthracis: Anthrax Bacillus cereus: Food poisoning Clostridium botulinum: Botulism Clostridium difficile: Pseudomembranous colitis Clostridium perfringens: Gas gangrene Clostridium tetani: Tetanus ```

Question 52

Endotoxin

Answer 52

LPS found in outer membrane of gram ⊝ bacteria (both cocci and rods). Composed of O antigen + core polysaccharide + lipid A (the toxic component). ``` ENDOTOXINS: Edema Nitric oxide DIC/Death Outer membrane TNF-α O-antigen + core polysaccharide + lipid A eXtremely heat stable IL-1 and IL-6 Neutrophil chemotaxis Shock ```

Question 53

Exotoxins which Inhibit protein synthesis: - Corynebacterium diphtheriae - Pseudomonas aeruginosa

Answer 53

Inactivate elongation factor (EF-2) - Diphtheria toxina - Exotoxin A

Question 54

Exotoxins which Inhibit protein synthesis: - Shigella spp. - Enterohemorrhagic E coli

Answer 54

Inactivate 60S ribosome by removing adenine from rRNA - Shiga toxin (ST)a - Shiga-like toxin (SLT)a

Question 55

Exotoxins which Increase fluid secretion: -Enterotoxigenic E coli

Answer 55

Heat-labile toxin (LT)a: Overactivates adenylate cyclase Heat-stable toxin (ST): Overactivates guanylate cyclase

Question 56

Exotoxins which Increase fluid secretion: - Bacillus anthracis - Vibrio cholerae

Answer 56

Edema toxina: Mimics adenylate cyclase ( cAMP). Cholera toxina: Overactivates adenylate cyclase ( cAMP).

Question 57

Exotoxins which inhibit phagocytic ability: - Bordetella pertussis

Answer 57

Pertussis toxina Overactivates adenylate cyclase ( cAMP)

Question 58

Exotoxis which Inhibit release of neurotransmitter: - Clostridium tetani - Clostridium botulinum

Answer 58

Both are proteases that cleave SNARE - Tetanospasmina: prevents release of GABA from Renshaw cells - Botulinum toxina: prevents release of ACh signals at neuromuscular junction.

Question 59

Exotoxins which Lyse cell membranes: - Clostridium perfringens - Streptococcus pyogenes

Answer 59

Alpha toxin: Phospholipase (lecithinase) that degrades tissue and cell membranes. Streptolysin O: Protein that degrades cell membrane

Question 60

Exotoxins which are Superantigens causing shock: - Staphylococcus aureus - Streptococcus pyogenes

Answer 60

Toxic shock syndrome toxin (TSST-1): Cross-links β region of TCR to MHC class II. Erythrogenic exotoxin A: overwhelming release of IL-1, IL-2, IFN-γ, and TNF-α.