Introduction to Bacteriology II:

Question 1

List the following related to Staphylococcus aureus:
-description:
-reservoir:
mode of transmission:
-virulence factors:

Answer 1

• desc: GP, cocci, aerobic, clusters
• reservoir: skin (axillae, perineum), nares
• mode of transmission: contact
• virulence factors: adhesin, protein A, capsule, leukocidin, hemolysin, catalase, DNAse, hyaluronidase, exotoxins: toxic shock syndrome toxin, exfoliatin, enterotoxin

Question 2

Describe the spectrum of disease for Staph aureus:

Answer 2

Diverse:

• skin and soft tissue infx (abscesses)
• bacteremia
• endocarditis
• pneumonia
• staphylococcal toxic shock syndrome
• staphylococcal scalded skin syndrome
• food poisoning

Question 3

Describe the following for Coagulase-negative staphylococci:

• most common species:
• description:
• reservoir:
• mode of transmission:
• virulence factors:
• spectrum of disease:

Answer 3

• commonly: S epidermidis
• desc: GP, cocci, clusters
• reservoir: skin
• mode of transmission: contact
• virulence factors: adhesin, capsule, biofilm
• spectrum of disease: bacteremia (catheter-associated), endocarditis (prosthetic-valve), prosthetic infections

Question 4

List 2 coagulase-negative GP bacteria:

Answer 4

1. Staphylococcus lugdunensis (similar to S aureus though)
   - disease: skin + soft tissue infx/abscesses
   - bacteremia, endocarditis, osteomyelitis
2. Staphylococcus saprophyticus
   - causes UTIs mostly

Question 5

Describe the following for Streptococcus pyogenes (Group A strep):

• description:
• reservoir:
• mode of transmission:
• virulence factors:

Answer 5

• desc: GP, cocci, chains
• reservoir: skin, pharynx
• mode of transmission: contact, droplet
• virulence fx: adhesin, M protein, capsule, hemolysins, hyaluronidase, streptokinase, streptococcal pyrogenic exotoxins (SPEs)

Question 6

Describe the spectrum of disease for Streptococcus pyogenes (Group A strep):

Answer 6

• pharyngitis: quinsy (tonsilar abscess)
• skin and soft tissue infx: impetigo, erysipelas, cellulitis, necrotizing fasciitis
• bacteremia
• TSS
• Septic arthritis
• Non-suppurative (rheumatic fever, glomerulonephritis)–> due to cross reactive Abs raised

Question 7

Describe the following for Streptococcus pneumoniae:

• description:
• reservoir
• mode of transmission
• virulence factors
• spectrum of disease:

Answer 7

• desc: GP, diplococci
• reservoir: oral-pharyngeal flora
• mode of transmission: droplet, contact
• virulence fx: capsule, autolysin, pneumolysin, protein A

-Spectrum of disease:
pneumonia, sinusitis, otitis media, meningitis, bacteremia

Question 8

What are the two most important species of Enterococcus?

Answer 8

1. E. faecium

2. E. faecalis

Question 9

Describe the following for Enterococcus spp. (E. faecium, E. faecalis):

• description
• reservoir
• mode of transmission
• virulence fx
• spectrum of disease

Answer 9

• desc: GP, cocci, chains
• reservoir: GI tract
• mode of transmission: contact
• virulence fx: adhesin, hemolysin (some)
• spectrum of disease: UTI, intra-abdominal infx

Question 10

Describe the following for Escherichia coli:

• descrip
• reservoir
• mode of tx
• virulence fx
• spectrum of disease

Answer 10

desc: GN, bacilli, aerobic
reservoir: GI tract

MoT: contact

VF: fimbriae, hemolysin, flagella, cytotoxin, enterotoxin

Disease: UTI, hospital-acquired pneumonia, intra-abdominal infx, gastroenteritis, hemolytic uremic syndrome

Question 11

List the enteric pathogens and describe them, their reservoir and MoT:

Answer 11

1. Enteric pathogens include:
   - enterotoxigenic E. coli (ETEC)
   - enterohemorrhagic E. coli (EHEC- O157:H7)
   - Salmonella spp
   - Shigella spp
   - Campylobacter spp (curved*)
   - Yersinia enterocolitica
2. desc: GN bacilli
3. reservoir: GI tract
4. MoT: contact

Question 12

What are the virulence fx and spectrum of disease for the enteric pathogens (GN bacilli)?

Answer 12

VF: enterotoxin, cytotoxin

SoD:

• gastroenteritis: water diarrhea (ETEC), bloody diarrhea (others)
• Hemolytic uremic syndrome (E coli 0157:H7)
• Bacteremia

Question 13

List the following for Neisseria meningiditis:

• desc
• Res
• MoT
• VF
• SoD

Answer 13

• desc: GN diplococci
• res: oral pharynx
• MoT: contact, droplet
• VF: capsule, IgA protease, endotoxin
• SoD: meningitis, meningococcemia (skin)

Question 14

Describe Neisseria gonorrhoeae:

desc, res, MoT, VF, SoD

Answer 14

desc: GN diplococci
res: genital tract

MoT: contact

VF: pili, antigenic variation, IgA protease

SoD: cervicitis, urethritis, pharyngitis, pelvic inflammatory disease, disseminated gonococcemia

Question 15

Describe Chlamydia trachomatis: desc, res, MoT, VF, SoD

Answer 15

• desc: intracellular pathogen
• res: genital tract
• MoT: contact
• VF: intracellular survival
• SoD: cervicitis, urethritis, pelvic inflammatory disease

Question 16

List the following for Clostridium spp. :

• Desc
• Res
• MoT
• VF
• SoD

Answer 16

• desc: GP bacilli (anaerobic)
  res: soil (C. tetani, C. botulinum , C. perfringens), hospital/GI tract (C. difficile)
• MoT: contact

VF: spores, exotoxins

SoD:

• Tetanus: C. tetani, neurotoxin
• Botulism: C. botulinum, neurotoxin
• Gas gangrene: C. perfringens, lecithinase
• Diarrhea (C. difficile, toxin A and B)

Question 17

List the following for Bacteroides spp.:

• desc
• res
• MoT
• VF
• SoD

Answer 17

• desc: GN bacilli (anaerobic)
• res: GI tract
• MoT: contact
• VF: lipase, protease, capsule
• SoD: intrabdominal abscesses, bacteremia