MSK Infections

Question 1

what is osteomyelitis

Answer 1

inflammation or bone and medullary cavity usually in one of long bones

Question 2

what are symptoms of osteomyelitis

Answer 2

fever, chills, fatigue, lethargy or irritability classic signs of inflammation include local pain, swelling or redness if you can see tendon or probe bone - deffs osteomyelitis

Question 3

what are most common causes of osteomyelitis in newborns (<4 months)

Answer 3

staph aureus

enterobacter sp

group A and B strep

Question 4

what are most common causes of osteomyelitis in children (aged 4 months to 4 years)

Answer 4

staph aureus

group A strep

haemophilus influenzae

enterobacter sp

Question 5

what are most common causes of osteomyelitis in children / adolescents (aged 4 years to adult)

Answer 5

staph aureus (80%)

group A strep

H influenzae enterobacter sp

Question 6

what are most common causes of osteomyelitis in adults

Answer 6

staph aureus

occasionally enterobacter or streptococcus

Question 7

what are most common causes of osteomyelitis in sickle cell anaemia patients

Answer 7

staph aureus most common

salmonella species common and unique to SCA

Question 8

what causes prosthetic joint osteomyelitis

Answer 8

mostly staph aureus or epidermis

rarely: propionibacterium acnes (upper limb), e coli, pseudomonas aeruginosa

Question 9

what are causes of contiguous osteomyelitis

Answer 9

open fractures diabetes / venous insufficiency

Question 10

what are haematogenous causes of osteomyelitis

Answer 10

PWID (viridans common here, pseudomonas, candida in heroin, eikenella corrodens in needle lickers and M tuberculosis)

Dialysis

Gauchers disease (lysosomal storage disorder)

Vertebral (most common, associated w epidural, psoas abscess, PWID, IV site infection, GU infection, SSTI, post op)

Question 11

what causes skeletal osteomyelitis

Answer 11

vertebral TB (potts) = often no systemic symptoms

kids = check reduced receptors for IFN-gammma R1, IL12 beta 1

adults = offer HIV test

causes gibbous deformity

Question 12

how is osteomyelitis diagnosed

Answer 12

indirect (scan) or direct (bone biopsy is gold standard)

might want to do MRI to make sure

Question 13

how is osteomyelitis treated

Answer 13

debridement / drainage / removal of joint

antibiotics for 6 weeks = do not give empirically, wait for results

acute = flucloxacillin IV (2 weeks) then 4 weeks oral therapy

chronic = oral flucloxacillin (if MRSA or allergy = doxycycline or co-trimoxazole)

if coliforms = seek advice

Question 14

what is septic arthritis

Answer 14

inflammation of joint space caused by infection

Question 15

what causes septic arthritis

Answer 15

can be blood borne organisms, extension of local infection, or by direct inoculation (following injection of joint or trauma)

*previously damaged joints ie RA more susceptible

Question 16

what are causative organisms in septic arthritis

Answer 16

staph aureus

streptococci

coagulase -ve staph (epidermis) = prosthetic joint

neisseria gonorrheae = sexually active patients

haemophillus influenze = pre school, not common now

Question 17

what are symptoms of septic arthritis

Answer 17

severe pain, red, hot, swollen plus limited movement

Question 18

how is septic arthritis diagnosed

Answer 18

clinical picture

joint fluid = yellow-green due to elevated nucleated cells

blood culture if pyrexial

exclude crystals

Question 19

how is septic arthritis treated

Answer 19

presumptive treatment to cover staph aureus = flucloxacillin clindamycin if allergic

if <5 years old, add cefriaxone for H influenzae cover

adjust when organisms confirmed

Question 20

what is knee bursitis

Answer 20

inflammation of small fluid filled sac (bursa) situated near knee joint

Question 21

what is pyomyositis

Answer 21

bacterial infection in skeletal muscles which results in pus-filled abscesses

Question 22

what causes pyomyositis

Answer 22

90% staph aureus

perineum = GNB

immunosuppressed = pseudomonas

B haemolytic strep

enterococcus clostridial infection = contaminated wounds (inject heroin)

Question 23

what are symptoms of pyomyositis

Answer 23

common in tropical areas but can also occur in temperate zones

Question 24

how is pyomyositis diagnosed

Answer 24

pus discharge culture and sensitivity

xray to rule out osteomyelitis

creatine phosphokinase (when muscle damaged, this leaks into blood)

MRI useful

Question 25

how is pyomyositis treated

Answer 25

drained surgically and antibiotics

Question 26

what is tetanus

Answer 26

serious muscle bacterial disease that is a neurotoxin (binds to inhibitory neurons, preventing release of neurotransmitters)

Question 27

what causes tetanus

Answer 27

clostridium tetani

(gram +ve anaerobic bacillus rods, spores found in soil, house dust, animal intestines, gardens etc, incubation time is 4 days - several weeks)

Question 28

what are symptoms of tetanus

Answer 28

painful contractions (particularly of jaw and neck) known as lock-jaw

Question 29

how is tetanus diagnosed

Answer 29

clinical picture (spastic paralysis)

culture (very hard! perhaps terminal spore - drumstick shape)

Question 30

how is tetanus treated

Answer 30

surgical debridement

antitoxin

supportive measures

antibiotics = penicillin / metronidazole

booster vaccination = toxoid

Question 31

how can tetanus be prevented

Answer 31

toxoid vaccine (2, 3, 4 months)