LG3.6 Microbiology of Joint Infections – Dr. Pettit

Question 1

What type of hemolysis does S. aureus cause?

Answer 1

Beta

Question 2

Is S. aureus gram +/-?

Answer 2

positve

Question 3

What is the catalase, coagulase, and fermenter type of S. aureus?

Answer 3

Catalase positive, coagulase positive, and it is a mannitol fermentor

Question 4

What are the main virulence factors of S. aureus?

Answer 4

• Protein A: Binds to Fc region of IgG
• Fibronectin-binding protein
• Cytolytic Exotoxins: PVL

Question 5

What type of hemolysis does S. epidermis have?

Answer 5

Gamma hemolysis

Question 6

What is the catalase, coagulase, and fermenter type of S. epidermis?

Answer 6

Catalase positive, coagulase negative, and mannitol fermentor negative

Question 7

What are the main virulence factors of S. epidermis

Answer 7

• Slime layer (attachement to tissues/prosthetics)
• Adhesins (collagen, fibrinogen, elastin)
• Lipases, proteases
• Biofilms

Question 8

What is the gram stain and shape of Kingella kingae?

Answer 8

Gram negitive and coccobacillus

Question 9

Where is Kingella kingae normal microbiota?

Answer 9

oropharynx

Question 10

What type of oxygen use does Kingella kingae have?

Answer 10

Facultative anaerobe

Question 11

What type of hemolysis does Kingella kingae cause?

Answer 11

Beta hemolytic

Question 12

Is Kingella kingae oxidase positive or negative?

Answer 12

Positive

Question 13

What is a leading cause of septic arthritis?

Answer 13

Kingella kingae

Question 14

What are the virulence factors of Kingella kingae?

Answer 14

• Pili

- Beta-hemolysin: lysis epithelial cells, synovial cells, macrophages

Question 15

What is the Gram stain and shape of Neisseria gonorrhoeae?

Answer 15

Small Gram Negative diplococcus

Question 16

What is the oxygen use of Neisseria gonorrhoeae?

Answer 16

Aerobe to facultative anaerobe

Question 17

What are the oxidase and catalase of Neisseria gonorrhoeae?

Answer 17

Oxidase positive and Catalase positive

Question 18

What are the main virulence factors of Neisseria gonorrhoeae?

Answer 18

• Adhesins
• Opa
• pili
• IgA1 protease
• Antibiotic resistance

Question 19

What types of antibiotic resistance does Neisseria gonorrhoeae?

Answer 19

• Efflux pumps
• Naturall competent for transformation
• Conjugation plasmids
• Evidence for biofilm formation

Question 20

What do Neisseria gonorrhoeae do to avoid the immune system?

Answer 20

• Bind sialic acid to their LOS
• Facilitated intracellular
• Antigenic and phase variation of Opa’s, pili, LOS
• Outer membrane blebbing

Question 21

What are the main symptoms of Gonococcal?

Answer 21

• low-grade fever
• petechial skin lesions
• migratory polyarthralgia
• Septic arthritis with increased pain and swelling of joints, purulent synovial fluids, and tenosynovitis

Question 22

Where and how many joints does Gonococcal normally infects?

Answer 22

-Polyarticular (can be mono)
-Knee, wrist, ankle and elbow
(less damage than non-gonococclal arthritis.

Question 23

What are the symptoms of nongonococcal infections?

Answer 23

• Fever, joint pain (hot, swollen)
• Impaired ranged of motion
• Usually monoarticular
• Knee most common

Question 24

What are the symptoms of prothetic joint infection?

Answer 24

• Sudden local joint pain

- Mechanical joint failure

Question 25

What are the three ways that a joint can become septic?

Answer 25

• Hematogenous spread
• Direct inoculation (bite,trauma)
• Extension of osteomyelitis

Question 26

What are the two major classes of septic arthritis?

Answer 26

• Nongonococcal (50% death rate)

- Gonococcal (low mortality rate)

Question 27

What is the role of white footed mice in the life cycle of Ixodes Scapularis?

Answer 27

• 2 year cycle of Ixodes scapulars
• Eggs uninfected
• Rodent reservoir (White footed mice) (Eats the eggs)
• Deer are not reservoirs but needed for completion of life cycle.

Question 28

What is the shape and gram stain of Borrelia burgdorferi?

Answer 28

• Gram negitive and spirochete

- Large size

Question 29

What type of oxygen use does Borrelia burgdorferi have?

Answer 29

microaerophile

Question 30

What is the vector of Borrelia burgdorferi?

Answer 30

• Blacklegged tick Ixodes
• Forest dweller
• All stages require blood meal.

Question 31

How is Borrelia burgdorferi cultured?

Answer 31

• Fastidious and slow growing
• Limited metabolic capabilities
• Generation time under optimal conditions 12-24 hours

Question 32

What are the virulence factors of Borrelia burgdorferi?

Answer 32

• Seems to suppress immune response in patients
• Blebs, biofilms, antigenic variation surface proteins.
• Very motile via axial filaments.

Question 33

What type of rash is indicative of lyme disease?

Answer 33

The bulls eye rash or erythema migraines.

Question 34

What are the main components of Early disseminated lyme disease?

Answer 34

• Dissemination to skin, heart, CNS, joints.
• Multiple erythema migrans
• Cardiac/neurologica complications. (Bell’s palsy, peripheral neuropathy)
• Ocular manifestations

Question 35

What are the main components of late lyme?

Answer 35

• Usually manifests as chronic arthritis

- Less often CNS problems

Question 36

Why is it less useful staining/culture for lyme disease?

Answer 36

Few spirochetes in blood/tissues

Question 37

What does it mean to do direct testing for lyme disease?

Answer 37

Looking for presence of microbe antigens uses known antibody

Question 38

What does it mean to do indirect testing for lyme diseases?

Answer 38

Looking for host antibodies directed against microbe antigens uses known antigens current exposure, previous exposure.

Question 39

What is the typical synovial WBC count for lyme arthritis?

Answer 39

Less than other bacterial arthritis etiologies, 20,000 to 60,000 cells/uL.