Bone, Joint, and Muscle Infection - Cross Flashcards Preview

Derm Rheum > Bone, Joint, and Muscle Infection - Cross > Flashcards

Flashcards in Bone, Joint, and Muscle Infection - Cross Deck (63):
1

Septic arthritis definition?

Typically refers to bacterial infection in a joint.

2

Septic Arthritis main route of infection? Others?

Usually hematogenously acquired

Other routes: Direct inoculation of bacteria into joint through surgery, trauma; contiguous spread from adjacent infected soft tissue or bone

3

Most common bug in "Step on a Nail" septic arthritis

Pseudomonas Aeruginosa

4

Most common bug in "Bit by my dog/cat" septic arthritis

Pasteurella Multocida

5

Most common bug in sickle cell septic arthritis

Salmonella

6

Pseudomonas Aeruginosa seen in these patients with septic arthritis?

IVDU (IV Drug Use), iatrogenic septic joint post surgical procedure/injection

7

Most common bug causing septic arthritis?

Staph aureus

8

Most important risk factor in septic arthritis?

preexisting abnormal joint architecture (i.e. RA, osteoarthritis, gout)

9

Risk factors for septic arthritis?

Abnormal joint architecture (most important), RA, osteoarthritis, gout, advanced age, diabetes, IVDU, immunosuppression, endocarditis

10

2nd most frequent cause of septic arthritis?

Strep; GAS, GCS, GGS

11

Neonate has septic arthritis. What bug? This bug causes septic arthritis in what other patients?

Group B strep, also in diabetics, those with malignances

12

Sacroiliac joint arthritis. Bug? Source?

Brucella from unpasteurized milk. Super rare. Dr. Cross hasn't seen it. 

13

Sternoclavicular septic arthritis or clavicular osteomyelitis. Most likely in what patients?

IV drug users

14

RA patients most likely to get septic arthritis from what bug?

Staph aureus

15

Most common joint affected in septic arthritis? 

The knee ( around 50%), mono-articular in 80-90% of cases

16

Most common joint affected in septic arthritis in children?

The hip

17

What bug causes gas gangrene?

Clostridium perfringens

18

Typical clinical presentation of a patient with septic arthritis

Intense pain and loss of function of that joint over 1-2 weeks; swelling, erythema, and increased joint warmth

19

What is characteristic of children with a septic hip?

they hold the hip in a flexed and externally rotated position, resist all ROM

20

Dx of septic arthritis requires what?

arthrocentesis of affected joint

21

Arthrocentesis facts

> how many cells usually required to make dx?

What type of cells are most abundant?

> how many cells pretty much is a dead giveaway for septic arthritis

Blood culture usually +?

> 50,000 usually septic

mostly neutrophils

> 100,000 = "you can pretty much bet this is a septic joint"

Blood cultures not often +

22

Most important thing to look for when aspirating a joint that is suspected to be septic?

The presence of crystals, if crystals are present then it's gout, not septic arthritis

23

Nonspecific lab findings seen in septic arthritis

Leukocytosis, elevated ESR and/or CRP

24

Early X-ray findings in septic arthritis

periarticular soft tissue swelling, nml osseous structures

25

Late X-ray findings in septic arthritis

Joint space loss, bony erosion/destruction

26

Ultrasound of septic joint is useful for what?

assess for presence of effusion and to guide needle aspiration if needed

27

Who are you going to immediately call if pt has septic arthritis?

Future drew aka ortho to come for drainage +/- irrigation and debridement

28

What bug causes a migrating arthritis

Gonococcus

29

Presentation of gonococcal arthrits

Triad of dermatitis (this is key), tenosynovitis, and migratory polyarthralgia

30

Epidemiology of Gonococcal arthritis. List a few

4x more common in women; <40 years old, lower socioeconomic status, multiple sex partners, illicit drug use

31

Pathogenesis of Gonococcal arthritis

Results due to occult bacteremia; infection could have been contracted days to months prior to dissemination

32

 Risk factors for gonococcal arthritis?

Women during menstruation, pregnancy, or postpartum; complement deficiencies (C5-C8)

33

General outcome of blood cultures

around 25% are positive; don't be fooled by negative blood cultures

34

Joints that gonococcal arthritis normally affects

Knees, wrists, ankles

35

What is this? What disease is this associated with? Early or late in progression of disease?

Q image thumb

Erythema migrans aka Bullseye rash = Early Infection Stage 1 Lyme disease

36

Common bug that causes lyme disease?

Borrelia burgdorferi

37

Lyme disease common where (geography)?

Common in northern states; NOT common in TN or Missouri.

- Hey lets go picket in front of the Infectious disease convention. Theyll start listening to us then. 

38

Stages of Lyme disease?

Stage 1 (early infection): erythema migrans; classic "bullet" rash

Stage 2 (early infection): Secondary skin lesions similar to initial lesions, but smaller; malar rash and conjunctivitis

Stage 3 (Persistent infection): intermittent attacks of joint swelling, especially large joints like the knee; even in untreated patients persistent arthritis normally resolves completely over several years

39

Test used to diagnose Lyme disease

Lyme western blot test

40

Alpha toxin associated with what bug? Main effect? 

clostridium perfringens, causes hemolysis leading to anemia

41

Gas gangrene in a patient causes what?

myonecrosis, necrotizing fasciitis

42

Leukocyte threshold for diagnosis of prosthetic joint infection

Threshold is much lower for leukocytosis in the synovial fluid when compared to a nml joint; prosthetic joints don't have the amount of vascular access for inflammatory cells

43

Treatment for prosthetic joint infection

REMOVE THE PROSTHESIS; prolonged abx therapy

44

Conjunctivitis, palsies, and meningitis are associated with what disease?

Early Infection Stage II of Lyme Disease

Features: include secondary skin lesions similar to initial lesions, but smaller; malar rash and conjunctivitis

- heart and nervous system including palsies and meningitis

45

Pt has abscess on spine, whats your likely dx?

Pott's disease (MTB osteomyelitis of spine)

46

Likely source and route leading to Pott's Disease

TB of lung spread hematogenously to spine

47

What bug causes double zone of hemolysis on blood agar?

clostridium perfringens

48

Osteomyelitis due to candida infection seen in what patients? Other bugs common to this subset of patients?

IV drug users. Staph aureus, pseudomonas, candida, and serratia

49

Causes of viral arthritis?

Rubella, Parvo B19, HCV, HBV

50

Characteristic course of viral arthritis?

short duration, most resolve spontaneously; small joints of the hands most commonly affected

51

How is the inflammation caused in viral arthritis

Immune complex formation; deposition in the joints causes inflammation

52

Most common causes of osteomyelitis

Common (>50% of cases) = Staph aureus, coag - staph (S. epidermidis, etc)

Less common (>25% of cases) = streptococci, enterococci, gram - (pseudo in someone stepped on a nail), anaerobes, MTB

53

Pathogenesis of staph aureus causing osteomyelitis?

Expresses high affinity adhesions to components of bone matrix that express fibronectin, laminin, collagen, etc

- it was bolded in her notes. 

54

Presentation of osteomyelitis

Nonspecific pain around the involved site with absence of systemic signs/symptoms

55

In osteomyelitis, what usually alerts you to the source?

Location, location, location

56

Osteomyelitis as a result of hematogenous seeding in adults is usually what type?

vertebral osteomyelitis

57

Hematogenous long bone osteomyelitis: mono or polymicrobial?

monobacterial

58

Contiguous infection osteomyelitis: mono or polymicrobial?

polymicrobial

59

Foot osteomyelitis in diabetics is usually due to what route of infection?

result of contiguous spread

60

Foot osteomyelitis after nail puncture usually due to what route of infection?

Result of direct inoculation

61

Long bones of the lower extremity are the most common location of infection in what subset of patients with osteomyelitis?

Acute hematogenous osteomyelitis in children, obviously a result of hematogenous seeding

62

Patient comes in with neck/back pain symptoms. What is an important question to ask?

Have you had recent injections in your back/neck. Rare but could be vertebral osteomyelitis due to iatrogenic cause (like injecting a long ass needle in someones neck)

63

Complement deficiency risk factor for what? What complements specifically?

gonococcal arthritis, C5-C8