Infection Flashcards
What is the name given to inflammation of bone and medullary cavity, usually located in one of the long bones?
Osteomyelitis
In what ways can osteomyelitis be classified?
- Acute / chronic
- Contiguous /haematogeneous
- Host status eg. Sickle cell = more likely to get salmonella in bone
Can osteomyelitis recur after treatment?
Yes
What is contiguous spread?
Spread of infection to structures adjacent to where it started
e.g. in open fracture
Who is most likely to get haematogenous osteomyelitis?
IVDUs
Prepubertal children
Central lines/ dialysis/ elderly
What can predispose to osteomyelitis?
- Open fractures
- Diabetes/ Vascular insufficiency
- Prosthetic joint infection
- Specific hosts and pathogens
What is the treatment for an open fracture?
aggressive debridement
fixation
soft tissue cover
What is the difference between direct and indirect confirmations of infection?
Direct = sample
Indirect = scan
Antibiotics can get into areas where pus collects TRUE/FALSE
FALSE
=> you have to debride the bone and THEN use antimicrobials
What types of bacteria usually infect open fractures?
Staphylococcus aureus
aerobic gram negative bacteria
How is osteomyelitis diagnosed in diabetes/vascular insufficiency?
Probe to bone (60% sens, 90% specific)
What joints are commonly affected in ostoemyelitis in PWIDs?
Unusual sites Sternoclavicular Joint Sternochondral Joint sacroiliac joint pubic symphysis
What uncommon infections can be seen in haematogenous osteomyelitis of PWIDs?
Pseudomonas
Candida
Eikenella corrodens (needle lickers)
Mycobacterium tuberculosis
What type of bacteria are most likely to infect dialysis patients?
Staphylococcus aureus (most common) Aerobic gram negatives
What is Osteitis pubis?
Urogynae procedures predispose to bacterial causes
Aseptic osteitis pubis
Triggered by surgery
What are the risk factors for osteomyelitis in the clavicle?
Neck surgery
Subclavian vein catheterisation
What do SAPH and CRMO stand for and in what age groups do they occur?
Synovitis Acne Pustolosis Hyperostosis Osteitis
- usually in ADULTS
Chronic Recurrent Multifocal Osteomyelitis
- usually in KIDS
How do SAPHO and CRMO present on an X-Ray?
Lytic lesions
note these conditions are NOT osteomyelitis
What type of abscess may predispose to vertebral osteomyelitis?
Epidural abscess
Psoas abscess
What symptoms can be present if a patient is thought to have vertebral osteomyelitis?
fever insidious pain tenderness neurological signs/ symptoms raised inflammatory markers
How sensitive is the first vs the second biopsy when testing for osteomyelitis?
60-80% 1st biopsy
90% 2nd biopsy
If still no answer consider open biopsy
Whilst waiting on a biopsy result from the lab, the patient must be given empirical antibiotics TRUE/FALSE?
FALSE
osteomyelitis = not a medical emergency
=> wait for lab results before antibiotics
How is vertebral osteomyelitis treated?
Drain large paravertebral/ epidural abscesses
Antimicrobials for 6 weeks
When would you repeat and MRI in vertebral osteomyelitis?
only if :
- Unexplained increase in inflammatory markers
- Increasing pain
- New anatomically related signs/ symptoms
What factors increase the risk of prosthetic joint infection?
- Rheumatoid arthritis
- Diabetes
- Malnutrition
- Obesity
What is the difference between planktonic and sessile infection?
Planktonic = bacteraemia Sessile = biofilm grows slowly very close to prosthesis and allows bacteria to aggregate
How is infection of a prosthetic joint usually treated?
Ideally removal of prosthesis and cement
Therapy for at least 6 weeks
Re-implantation of the joint after aggressive antibiotic therapy.
What microbes are often responsible for infection of a prosthetic limb?
Gram + - staph aureus - Staph epidermidis - Propionibacterium acnes (upper limb prostheses) RARE: streptococcus/enterococcus
Gram -
- E-coli
- Pseudomonas aeruginosa
(Also Fungi/mycobacteria sp.)
How can infection spread to cause septic arthritis?
- from infectious focus in adjacent tissue (e.g. abscess)
- from focus of osteomyelitis in adjacent bone
- direct invasion from penetrating wound
- haematogeneous spread
What organisms are most likely to cause septic arthritis?
- Staphylococcus aureus
- Streptococci
- Coag neg staphylococci (prosthetic joints)
- Neisseria gonorrheae (If sexually active)
When is it okay to give patient empirical antibiotics?
When there is suspicious of SEPSIS
What is polymyositis?
bacterial infection of the skeletal muscles which results in a pus-filled abscess
What symptoms of tetanus make it a muscular disease?
Neurotoxin it releases causes spastic paralysis.
Binds to inhibitory neurones
=> preventing release of neurotransmitters
What treatment can be given in tetanus?
Surgical debridement. Antitoxin. Supportive measures Antibiotics (Penicillin / Metronidazole) Booster vaccination
What microbes often cause myositis?
Viral – diffuse
= HIV, Influenza, Rabies, Chikungunya etc
Protozoa
fungal
