Microbiology Flashcards
Treatments of choice for osteomyelitis (2)
- Aggressive debridement
- Antimicrobials (IV)
Which % of all open fractures become infected?
Between 3-25%
Non-union and poor wound healing can indicate which condition?
Osteomyelitis
Common isolate in osteomyelitis
S. aureus
Osteomyelitis is only ever spread by direct inoculation. True/false?
False - can be haematogenous.
Needle-licking PWID are likely to develop which isolate?
Eikenella corrodens
Which % of dialysis patients develop infection?
7%
Most common pathogen in dialysis patients’ osteomyelitis?
S. aureus
Sickle Cell disease can predispose to osteomyelitis. True/false?
True
“A lysosomal storage disorder which can mimic bone crisis” is likely to describe which disease?
Gaucher’s Disease
Gaucher’s disease often affects which bone?
Tibia
Diabetic / vascular osteomyelitis is often polymicrobial. True/false?
True
The first-line investigation for a deep ulcer you suspect to cause osteomyelitis?
Probe-to-bone test + inflammatory markers
If there’s a positive probe to bone test in a deep ulcer, what is the next step in diagnosis of osteomyelitis?
Plain radiograph
In a deep ulcer which is an osteomyelitis concern, you check radiographs (2nd stage investigation) to find there’s no evidence of osteomyelitis. What’s the next step?
Osteomyelitis unlikely, consider soft tissue infection (2 weeks treatment)
If a radiograph is consistent with osteomyelitis, BUT not characteristic, what’s the next line of studies?
MRI
What is the definitive/ final investigation for diagnosis of osteomyelitis?
Bone biopsy
Haematogenous osteomyelitis presents in which 3 groups?
- Prepubertal children
- PWID
- Central lines/ dialysis patients
Urogynae procedures can predispose to which form of osteomyelitis?
Osteitis pubis
Neck surgery can predispose to which form of osteomyelitis?
Clavicle osteo
Which pathogens are common in sickle cell osteomyelitis? (2)
- Salmonella
- S. aureus
Gaucher’s disease is always infectious.
False
Plain X-rays are useful in diagnosing bone infection. True/false?
False
Which imaging modality could be useful in diagnosing bone infection?
Technetium bone scan (detects osteoblast activity)
Most common cause of acute osteomyelitis (1)
-Post trauma or open ounds
Most common organism causing acute osteomyelitis (2)
1) S. aureus
2) May also be haemophillus in children
Does vertebral OM always present with fever?
No, only 50% of cases do
What makes SAPHO/CRMO different from regular OM?
They are multifocal
SAPHO is adults/kids?
Adults
In OM, empiric antibiotics should be used ASAP. T/F?
False, wait until suggestive results
How is vertebral OM treated? (4)
1) Drain abscess
2) Antibiotics for 6 weeks
3) Monitor ESR (should decrease by >50%)
4) Repeat MRI if ESR raises, pain increases or new symptom
Skeletal TB is AKA
Pott’s Disease
Skeletal TB is often symptomatic, T/F?
False - often asymptomatic
Do skeletal TB / Pott’s Disease patients commonly have pulmonary TB?
Less than 50% have pulmonary TB
If prosthetic OM develops <1 month from insertion of prosthesis, what was the likely source?
Wound sepsis
If prosthetic OM develops >1 month from insertion of prothesis, what is the likely source?
Intraoperative
PVL treatment
Fluclox
What is a S. epidermidis virulence factor in OM?
Slime
Pyomyositis describes what kind of infection
Pus-forming muscle infection
Septic arthritis common cause
S. aureus
How is septic arthritis diagnosed? (3)
1) Joint aspirate
2) C&S
3) Blood cultures if pyrexial (30-60% sensitive)
What’s the standard treatment choices & route for acute OM or septic arthritis?
Flucloxacillin IV 2g QDS for 2 weeks, PO antibiotics for maximum 4 weeks
What’s the antibiotic treatment & route for chronic OM?
PO flucloxacillin
What’s the antibiotic treatment & route for MRSA-OM?
IV vancomycin
Tetanus gram stain profile & growth condition
Gram positive rod, strict anaerobe
“Drumstick shaped bacteria” is code for
C. tetani
Treatment of tetanus (4)
1) Antitoxin
2) Surgical debridement
3) Supportive antibiotics (penicillin, metronidazole)
4) Booster toxoid vaccine
Is the tetanus vaccine live?
No, it’s a toxoid
Which book is recommended for vaccine advice in children?
The Green Book
Children with skeletal TB should be offered which test? What should adults be offered?
Children -> IFNgamma assay
Adults -> HIV test
What are the cardinal signs of inflammation?
Rubor (redness) Calor (heat) Dolor (pain) Tumour (swelling) Functio lasea (loss of function)
What bloods are useful in OM diagnosis?
CRP, PV, WBC count, blood cultures, ESR
Technetium bone scan shows what kind of activity?
Osteoblastic
What organism causes OM in children?
Haemophillus
How is pus in OM treated?
Lancing, drainage
What is a Brodie’s abscess?
An abscess that develops within bone due to a deep OM. The outer bone dies and acts as sequestrum, protecting the infection.
What is a complication of Brodie’s abscess?
Involucrum formation.
What is involucrum?
A layer of bone which forms external to the periosteum of a bone with a deep OM
Are blood tests useful in diagnosis of COM?
No
Cellulitis common causative organisms?
Staphs & streps
How is cellulitis treated? (NHST antibiotic man)
Flucloxacillin 1g QDS, IV/PO for 7 days
“Bony sinus” is a keyword for what
A DEEP bone infection
2-step surgery is how successful in controlling infection in OM?
80-90%
