Musculoskeletal infections Flashcards by Sasha Murdoch

What are the 5 main types of oesteoarticular infections

Prosthetic-joint infection
Septic arthritis
Post-traumatic infection
Vertebral osteomyelitis
Diabetic foot infection

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What are the 3 most common causative pathogen of osteoarticular infections?

Staph aureus
Streptococci
Coliforms

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What are the most likely pathogens of a prosthetic joint infection

Coagulase negative staphylococci

Proprionobacteria (diptheroids)

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What are some less common pathogens

Pseudomonas aeruginosa

Kingella (in children

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What are 3 risk factors for developing an osteoarticular infection

Sickle cell
Immunocompromised
Diabetes

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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)

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What does SIRS stand for

Systemic Inflammatory Response Syndrome

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SIRS is present when there are 2 or more of what

Temperature >38 or 90bpm
RR >20bpm or
PaCO2 12000 cells/mm3 or

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What is septic arthritis

An infection of the joint space

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How are organisms introduced to the joint space

Haematogenous spread
Contiguous spread (infected bone)
Direct inoculation (injection / trauma)

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What are the main pathogens of Septic arthritis

MSSA

Streptococci

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What tests should be performed to diagnose acute septic arthritis

Blood cultures if pyrexial 
CRP, FBC, U&amp;E, lactase, ESR
Joint fluid aspirate/ washout for microscopy and culture 
cruystals white cells and gram stain 
US scan, XR, MRI, CT, bone scan

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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)

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Define osteomyelitis

Inflammation of bone and medullary cavity, usually long bones or vertabrae

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In which population is there an increasing incidence of osteomyelitis

Children

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Why might osteomyelitis recur

If the treatment is suboptimal

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In what 4 ways can acute osteomyelitis spread?

Haematogenous (most likely - often towards the knee - femur, tibia)
Contiguous
Peripheral vascular disease associated
Prosthesis associated

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Why are infants more at risk of septic arthritis

Due to vessels crossing metaphysis to epiphysis

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Where in the body is there most likely to be haematogenous spread

Femur/ tibia

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In what 4 joints may acute osteomyelitis spread into joint space and why?

Shoulder ankle hip elbow

because the metaphysis is intracapsular

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If there is a delay in treating acute infection what can this lead to

A high risk of abscess
permanent damage
septicaemia

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What are 4 risk factors for infections in prosthetic joints

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Rheumatoid arthritis
Diabetes
Malnutrition
Obesity

What are the 3 types of implant infection

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Early postoperative
Delayed (low grade)
Late

What is an ideal treatment for a prosthetic joint infection

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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

Musculoskeletal infections Flashcards

(53 cards)