Musculoskeletal infections Flashcards
What are the 5 main types of oesteoarticular infections
Prosthetic-joint infection Septic arthritis Post-traumatic infection Vertebral osteomyelitis Diabetic foot infection
What are the 3 most common causative pathogen of osteoarticular infections?
Staph aureus
Streptococci
Coliforms
What are the most likely pathogens of a prosthetic joint infection
Coagulase negative staphylococci
Proprionobacteria (diptheroids)
What are some less common pathogens
Pseudomonas aeruginosa
Kingella (in children
What are 3 risk factors for developing an osteoarticular infection
Sickle cell
Immunocompromised
Diabetes
What are the clinical presentation of acute bone and joint infections
Temperature / systemic signs
Pain/ swelling/ redness over area
Reduced mobility/ movement of joint/ held in flexed position
Children (not feeding/ playing/ cranky)
What does SIRS stand for
Systemic Inflammatory Response Syndrome
SIRS is present when there are 2 or more of what
Temperature >38 or 90bpm
RR >20bpm or
PaCO2 12000 cells/mm3 or
What is septic arthritis
An infection of the joint space
How are organisms introduced to the joint space
Haematogenous spread Contiguous spread (infected bone) Direct inoculation (injection / trauma)
What are the main pathogens of Septic arthritis
MSSA
Streptococci
What tests should be performed to diagnose acute septic arthritis
Blood cultures if pyrexial CRP, FBC, U&E, lactase, ESR Joint fluid aspirate/ washout for microscopy and culture cruystals white cells and gram stain US scan, XR, MRI, CT, bone scan
What is the antibiotic treatment for septic arthritis and by what route should it be given
How long should the treatment be for?
Staph aureus –> FLUCLOXACILLIN (high dose to get into the joint)
Usually needs to be IV for joints
2-4 weeks (2 minimum)
Define osteomyelitis
Inflammation of bone and medullary cavity, usually long bones or vertabrae
In which population is there an increasing incidence of osteomyelitis
Children
Why might osteomyelitis recur
If the treatment is suboptimal
In what 4 ways can acute osteomyelitis spread?
Haematogenous (most likely - often towards the knee - femur, tibia)
Contiguous
Peripheral vascular disease associated
Prosthesis associated
Why are infants more at risk of septic arthritis
Due to vessels crossing metaphysis to epiphysis
Where in the body is there most likely to be haematogenous spread
Femur/ tibia
In what 4 joints may acute osteomyelitis spread into joint space and why?
Shoulder ankle hip elbow
because the metaphysis is intracapsular
If there is a delay in treating acute infection what can this lead to
A high risk of abscess
permanent damage
septicaemia
What are 4 risk factors for infections in prosthetic joints
Rheumatoid arthritis
Diabetes
Malnutrition
Obesity
What are the 3 types of implant infection
Early postoperative
Delayed (low grade)
Late
What is an ideal treatment for a prosthetic joint infection
Removal of prosthesis and cement
Re implantation of the joint after antibiotic treatment
What is necrotising fasciitis
Uncommon but acute and severe infection of the subcutaneous soft tissues
What areas of the body can be affected by necrotising fasciitis
Limbs
Abdominal wall
perineal and groin area
post operative wound
Describe the clinical picture of Necrotising fasciitis
Highly painful
some signs of inflammation
spread through tissues very raidly
systemic toxicity
What is type 1 necrotising fasciitis
Anaerobes plus multiple other bacteria (synergistic gangrene)
What is type 2 necrotising fasciitis
Flesh eating bacteria
Group A streptococcus
How can we diagnose necrotising fasciitis
Pain disporportionate to superficial appearances
Swabs and tissues biopsy for microbiology gram stain and culture
Blood cultures
CRP, FBC, clotting U&E
What are the infection control procedures for a patient with necrotising fasciitis
Standard precautions Single room gloves aprons risk assess need for droplet precautions
What is gas gangrene
Clostridium perfringens (part of normal bowel flora) Gram positive strictly anaerobic rods
What is the causative organism of tetanus
Clostridium tetani
Gram positive strictly anaerobic rods
Where is tetanus found
Soil
gardens
animal bites
What happens in tetanus
Neurotoxin causes spastic paralysis
It binds to inhibitory neurones, preventing release of neurotransmitters
What is the incubation period of tetanus
4 days to several weeks
What is the treatment for tetanus
Clinical suspicion Surgical debridement Antitoxin Supportive measure Penicillin/ metronidazole Booster vaccination.... toxoid
When is the tenaus vaccination given
2,3,4 months
What might be the cause of sepctic arthritis if the patient is sexually active
Gonnorhoea
What is PVL? And what effect does it have on a patient
A toxin - poisonous protein
Toxin can be quite damaging to patients
Aggressive infection
More commonly found in younger people
What are coliforms
A group of organisms which normally live in the bowel - they can give rise to an osteomyelitis
What can be a sign of a PVL infection
Recurrent boils
How do we measure treatment
CRP response - should be decreasing if the treatment is working
Why do we look for crystals in the diagnosiss of acute septic arthritis
To rule out gout and pseudogout
What should be added in for children antibiotic treatment and why?
Ceftriaxone (for H influenzae/ Kingella cover)
What type of patients are more likely to get salmonella osteomyelitis
Those with sickel cell
When do we start antibiotics of chronic osteomyelitis
When SIRS is absent and when cultures have been taken so we know the exact antibiotic to use
Necrotising Fascitis is a medical emergency - true or false
True - can be minutes - hours before mortality
How does clindomycin work?
It stops Strep A producing a toxin as well as fighting the infection
What are Clostridium perfringens
Part of the normal bowel flora
Gram positive strictly anaerobic rods
How does Gas Gangrene cause an infection
The spores get into the tissue.
This causes the tissue to die and anaerobic conditions
WHat happens if the the spores germinate
There is an accumulation of gas bubbles in tissues space gas gangrene (crepitus
What is the treatment for Gas gangrene
Urgent debridement in theatre
Antibiotic in high doses (penicillin, metronidazole - either or both)
Possibly hyperbaric oxygen
