Bacterial Infections

Question 1

Sources of osteomyelitis

Answer 1

hematogenous
contiguous
trauma, fx or surgery

Question 2

Hematogenous - OA

Answer 2

spread through the blood (infection elsewhere in the body)
monomicrobial monomicrobial
Staphylococcus aureus

Question 3

Contiguous - OA

Answer 3

Puncture wound, foot ulcer (concern with diabetes)
Infection is adjacent or near a bone
Polymicrobial: Gram + cocci, Gram – rods, anaerobes

Question 4

Trauma, fx, or surgery

Answer 4

nosocomial infection

S. aureus

Question 5

Risk factors of OA

Answer 5

-Diabetics
Foot injury
-Surgery
-Artificial surfaces
Joints
Screws
-IV drug users

Question 6

Sx of OA

Answer 6

-Fever - develops in infection are hematogenous
-Chills
-Fatigue
-Localized pain** e.g. pt with hip replacement
-Inflammation (redness, swelling, heat, and pain)
-Infection due to trauma:
Purulent drainage from wound = cloudy and pus

Question 7

Dx of OA

Answer 7

Blood sample:
Gram stain & culture (grow it)
Positive identification in about 50% of cases*
CBC: increase in WBC
ESR (erythrocyte sedimentation rate): increased
take DRAINAGE
Bone Biopsy: Gram stain & culture
Imaging- what it looks like but won’t tell you how to tx

Question 8

Ab sensitivity test

Answer 8

what antibiotic the bacteria is sensitive to

NEED TO KNOW FOR MRSA

Question 9

Tx of OA

Answer 9

Drainage- want this to have the infection out
Debridement- scrape out infection as possible
Surgery-
Long term IV antibiotics

Question 10

Long term IV tx for OA

Answer 10

6 wks to 2 months
IV line

S. aureus 
-nafcillin
-oxacillin 
MRSA 
-vanco

Question 11

Staph a.

Answer 11

Most common cause of osteomyelitis

• hematogenous
• contiguous
• trauma/fracture/surgery

opportunistic pathogen
nosocomial infection
-device related
-postsurgical complications

Question 12

Stap A. characteristics

Answer 12

gram-positive cocci
gram stain - purple 
grape like clusters 
catalase +
Coagulase +

Question 13

why is biofilm important in OA?

Answer 13

allows it to attach to the surface

• difficult to grow in culture
• microbial community attached to a surface
• encased exopolysaccharide matrix or glycocalyx
• highly resistant to antibiotics and immune system

Question 14

Heart valves and teeth

Answer 14

biofilm can attach to these surfaces

Question 15

best tx of biofilm

Answer 15

debridement
replacement of the prosthetic
tx with antibiotics

GET RID OF BIOFILM right away!!!!

Question 16

MRSA

Answer 16

• Methicillin Resistant Staphylococcus aureus
• mecA gene encodes PBP2a (pencillin-binding protein)
• Methicillin (beta lactams) can not bind to PBP2a, cell wall synthesis is not inhibited.

Question 17

DOC for MRSA

Answer 17

vanco

Question 18

staph a and enterotoxin

Answer 18

affect GI system

Question 19

P. aeruginosa - OA

Answer 19

IV drug use

Puncture wounds

Question 20

Characteristics of P. aeruginosa

Answer 20

Gram-negative rod
Highly antibiotic resistant
Characteristic color
Characteristic sweet, grape like odor
Forms a biofilm
Alginate capsule

Question 21

Pott’s disease

Answer 21

OA caused by TB

Question 22

OA caused by salmonella

Answer 22

in children with sickle cell anemia

Question 23

Reactive arthritis

Answer 23

autoimmune condition due to an infection at a different location in the body.

no infection present at the joint
due to infection somewhere else in the body

Question 24

Reiter’s syndrome

Answer 24

classic reactive arthritis 
TRIAD: 
1. inflammation of joints, polyarticular, knee 
2. conjunctivitis 
3. urethritis/cervicitis

Question 25

Pathogens assoc. with Reactive arthritis

Answer 25

Usually presents 2-4 weeks after primary infection. GI infection Examples: Campylobacter jejuni, Salmonella, Shigella and Yersinia STD: Chlamydia- urethritis/cervicitis/conjuctivitis

Question 26

Disease association to reactive arthritis

Answer 26

HLA-B27

Question 27

Septic arthritis

Answer 27

inflammation due to infection of the joint. (suppurative, purulent, infectious) pus-producing organism synovial fluid will be cloudy - infection

Question 28

pathogens involved in septic arthritis

Answer 28

gonococcal | nongonococcal

Question 29

Sources of infection

Answer 29

Hematogenous Contiguous- near the joint Direct inoculation- antiinflammatory injection (unclean)

Question 30

Joints affected in septic arthritis

Answer 30

knee 40-50% hip 20-25% ankle/shoulder/elbow 10-15% wrist 10%

Question 31

Risk factors for septic arthritis

Answer 31

``` History of arthritis Prosthetic joint - 2-10% of all recipients Gonorrhea Trauma Immunosuppressed IV drug users ```

Question 32

Symptoms

Answer 32

``` Fever Joint pain -monoarticular -polyarticular- may be traveling Inflammation Limitation of movement- can't move joint ```

Question 33

Dx for septic arthritis

Answer 33

``` Patient history very important: gonorrhea, any issues at the joint? Joint Fluid -Gram stain -Culture CBC: increase in neutrophils ESR CRP Imaging Techniques ```

Question 34

Septic Arthritis : Gonorrhea

Answer 34

``` Neisseria gonorrhoeae -sexually transmitted Most common cause of septic arthritis in young, sexually active adults Gram negative, diplococci**** Fastidious Thayer-Martin Chocolate agar********* Pili: Attachment, Antigenic variation ```

Question 35

Thayer-Martin Chocolate Agar

Answer 35

blood is lysed to release heme | Ab added to help niserria grow

Question 36

Gonorrhea vs. stap a.

Answer 36

Most common cause of septic arthritis in young, sexually active adults Other than this population=> think stap a.

Question 37

Gonococcemia

Answer 37

spreading through blood stream why in females > males (1-3% of women, lower for men)? => women tend to be asymptomatic for gonorrhea

Question 38

Migratory joint - Gonoccemia

Answer 38

polyarticular | different joints at different times

Question 39

SA - Early prosthetic joint infections! | <3 months

Answer 39

staph a.

Question 40

SA - Delayed infection of prosthetic joint | >3 months

Answer 40

CoNs | -coagulase negative stapyloccocus e.g. staph epidermis

Question 41

Staph a. - Septic arthritis

Answer 41

nongonoccocal Adults Children > 2 years old Monoarticular

Question 42

Other Nongonococcal pathogens- SA

Answer 42

Steptococcus sp. | P. aeruginosa - IV drug users

Question 43

Gonorrhea in women - complication

Answer 43

PID | infertility

Question 44

Staph. a. no culture

Answer 44

why no growth ? biofilm

Question 45

SA - Lyme Disease

Answer 45

Pathogen: Borrelia burgdorferi Early: bull’s eye rash Disseminated: pain in joints, bones and muscles Late: recurring arthritis, large joints 60-80% of untreated individuals develop arthritis

Question 46

Tx of SA

Answer 46

``` Rapid destruction of the joint Drainage of infected joint Antibiotics Several weeks IV Gonococcal: ceftriaxone S. aureus: nafcillin or oxacillin MRSA: vancomycin ```

Question 47

Surgery related SA

Answer 47

Prosthetic | ---Tx: Surgery to replace joint + 6 weeks IV antibiotics