MSK Infections Flashcards
gram positive penicillin allergic
vancomycin
staph epididermis treatment
vancomycin
h influenzae treatment
ceftriaxone
anaerobes treatment
metronidazole
anaerobes example
clostridium and bacteriocides
gram negative treatment
gentamicin
gram negative examples
bordatella, h influenza, coliforms, h pylori, campylobacter
adult osteomyelitis
inflammation of the bone and medullary cavity, usually located in one of the long bones
how can adult osteomyelitis be classified
acute/chronic conitguous/haematogenous host status eg presence of vascular insufficiency
what forms of adult osteomyelitis can progress to chronic
ALL
how long must the antibiotic course for adult osteomyelitis be
minimum 6 weeks as can recur after treatment
clinical approach to infection
clinical suspicion - history is key examination confirmation treatment
how can infection be confirmed
indirect - CT scan and MRI (best) direct - bone biopsy gold standard, also surgical sample, histology wound swabs and blood cultures are not very useful except in septic patients
what is the gold standard direct investigation for infection
bone biopsy
what is the best indirect investigation for infection
MRI
predispoing conditions
- Sickle cell anaemia
- IV drug user
- DM
- Immunosuppression
- alcohol excess
open fractures
early management is key - debridement, fixation and soft tissue cover the clinical clue is non union and poor wound healing
infection of open fractures
3-25% get infected - tends to be S aureus and aerobic gram negative bacteria
name 2 aerobic gram negative bacterias
pseudomonas and legionella
diabetes/vascular insufficiency
are often polymicrobial and the diagnosis can be challenging are difficult to clear once infection is established
CF of diabetes/vascular insufficiency
Microneurovascular dysfunction with loss of nociceptive reflex and inflammatory response - diminished sensation in feet - ischaemic toes - pressure ulcers - diabetic foot ulcer
treatment of diabetic foot ulcers
debridement and antimicrobials
what is the likely bacteria in mild to moderate diabetic foot ulcer
s aureus - flucloxacillin
who is haematogenous osteomyelitis seen in
prepubertal children, PWID,, central lines/dialysis/elderly
haematogenous osteomyelitis - PWID
can be contiguous, haematolgoical or direct inoculation. often seen at unusual sites
haematogenous osteomyelitis - PWID organisms
staph and strep and often unusual pathogens
dialysis patients with haematogenous osteomyelitis
high staphlocccal colonisation rates there are often co morbidities present
osteitis pubis
inflammation of the pubic symphysis. well known complication of invasive procedure about pelvis, may also occur as an inflammatory procedure in athletes
clavicle osteomyelitis
v unusual, risk factors are neck surgery or subclavian vein catheterisation
typical causative organism of sickle cell osteomyelitis
12% of people with sickle cell disease get it
salmonella
gaucher’s disease
lysosomal storage disease that may mimic bone crisis and often affects the tibia
bone crisis
severe bone pain as a result of infarction
pathogens in gaucher’s disease
if it is bone crisis - sterile if infected - s aureus
SAPHO and CRMO
SAPHO in adults, CRMO in kids causes general constitutional symptoms and multifocal osteitis. there is a genetic role
how does vertebral osteomyelitis occur
mostly haematogenous, but can be associated with local spread from epidural or psoas abscess
how does one confirm vertebral osteomyelitis
MRI
CF of vertebral osteomyelitis
fever and inc WCC and inflammatory markers insidious pain and tenderness neurological symptoms and signs
clinical approach to infection: treatment
debridement antimicrobials - AFTER microbial diagnosis unless there s acute presentation or sepsis
treatment of vertebral osteomyelitis
large abscesses need to be drained 6 week minimum antimicrobials
when to repeat MRI in vertebral osteomyelitis
increasing pain, inc in inflammatory markers or new signs/symptoms
skeletal TB
pott’s disease - often no systemic symptoms - some have skin and soft tissue infection - less than half have pulmonary TB
treatment of pott’s disease
check reduced receptors in kids for IFN gamma etc offer HIV test in adults
what are the risk factors for infection in prosthetic joints
rheumatoid arthritis (IS drugs?), diabetes, malnutrition and obesity
why are prosthetic joints difficult to treat
a biofilm (layer of bugs lying on top of joint) forms and antibiotics struggle to penetrate it
how do bugs get into joints
during surgery (can take a month to present) or through blood stream
when is s epididmeris colonisation considered serious
only when multiple showings of it - normal commensal of skin
planktonic bacteria
free in the blood - causes bacteraemia
sessile bacteria
sits on joint/metal/plastic and forms a biofilm a phenotypic transformation of planktonic bacteria
diagnosis of prosthetic joint infection
is difficult as it is caused by organisms that are common contaminants culture of tissue is taken
treatment of prosthetic joints
epididmeris- vancomycin ideally the prosthetic joint is removed, in some elderly people it is just derided but this has a poor prognosis
septic arthritis
inflammation of the joint space caused by infection
when should septic arthritis be considered
in any acutely inflamed joint as it can destroy a joint in under 24 hours
where does septic arthritis commonly affect
knee - 50% cases
how does the joint become infected in septic arthritis
blood borne, direct inoculation, or extension of local infection
what severe thing is occasionally seen in septic arthritis
PVL producing S aureus - increases virulence
cause of septic arthritis in prosthetic joints
coagulase negative staphylococci eg staph epidermidis
cause of septic arthritis in sexually active ppl
Neissera gonorrhoea (aerobic gram negative diplococci)
cause of septic arthritis in pre school children
H influenzae - less common now due to vaccination
key investigation for septic arthritis
joint aspiration for synovial fluid microscopy and culture
what must be excluded in septic arthritis
gout - can present in same way
<5 with septic arthritis treatment
Ceftriaxone (h infuenzae)
pyomyositis
bacterial infection of the skeletal muscles that result in a pus filled abscess
cause of pyomyositis
90% staphylococcal
what is often the cause of pyomyositis in contaminated wounds
clostridial infection
myositis
canbe viral, protozoic or fungal
what is tetanus caused by
clostridium tetani - gram postiive anaerobic rods forms spores
clinical features of tetanus
exotoxin causes muscle spasms and rigidity spasms can be induced by bright lights and loud noises
classical description of tetanus
locked jaw
incubation period for tetanus
4 days to several weeks
tetanus treatment
surgical debridement antitoxin supportive measure antibiotics not that useful as due to toxin
what do tetanus survivors need
booster vaccine - not immune
