wk 10 - bone and soft tissue infections Flashcards
erysipelas is
bacterial infection of the upper half of dermis
cellulitis is
bacterial infection of the lower half of dermis into the subcutaneous fat
if someone has systemic symptoms where should you refer to?
emergency department
patient characteristics of cellulitis and erysipelas (differences)
Age
How fast does it progress
Line of demarcation
Organism
cellulitis
-occurs in middle age/older
-slowly increases
-line of demarcation ill defined
-organism: strep pyogenes 2/3, staph aureus 1/3
erysipelas
-occurs in children
–rapidly
-clear line of demarcation
-can have vesicles
-organism: strep pyogenes
risk factors of skin infection
impaired barrier function
weakened immune system
iV drug use
complications of cellulitis
progression to
lymphangitis
abscess formation
gangenous cellulitis
necrotising fascitis
sepsis
death
treatment guidelines for erysipelas without systemic features
referral for IV:
- phenoxymethylpenicllin
OR - brocaine benzylpenicillin
if delayed nonserve hypersensitivity
2. cefalexin
if immediate nonsevere/severe or delayed severe
2. clindamycin
signs in cellulitis to be concerned about
soft, fluctuant areas - abscess formation
red streak from area of cellulitis or fast spreading of redness
significant pain not aleviating by medications
inability to move joint because of pain
patients with diabetes, cancer, immunosuppressant
systemically unwell
main role of podiatrist in management /prevention of these infections?
maintain barrier function of the skin
spetic arthritis organisms involved and how many joints affected?
presents usually as single joint infection
organisms:
1. staph aureus or
2. gonorrhoeae (recent STI?)
how to diagnose septic arthritis/investigations
joint aspiration for:
- cell count
- crystals
-MC and S
blood culture
radiograph
what monoarthritis presenting condition should be considered in ATSI populations
acute rheumatic fever
management of septic arthritis in hospital
-drainge of pus and joint irrigation
-synvoectomy to remove pathogens and help with diffusion of antibiotic into joint
-early treat will reduce joint damage
osteomyelitis
inflammation/ infection of the bone or bone marrow
organism: staph aureus can also by fungi
red fag: probe to bone in ulcers
signs and symptoms of osteomyelitis (acute v chronic)
acute
-pain at site
fevers
chronic
-weight loss
-prolonged systemic signs
radiographic signs of osteomyelitis
deep soft tissue swelling
periosteal reaction
cortical irregularity
bone demineralisation
how does infection get to bone
20% of people dont carry staph aureus
60% are intermittent carriers
20% of people always carry staph aureus (reservoirs) (1/5)
opportunistic infections- typically staph present in nose, is same as skin infection and osteomyelitic infections
how does bacteria reach bone?
- spread via blood (haematogenous)- infection in somewhere else in body
- contiguous spread- overlying wound (common in podiatry- ulcers)
- direct implantation secondary to trauma or surgery
how can staph in the nose get to a distal site ?
doesnt have to be through contact but can be via blood
bacteria that cna remain undetected and not raising and inflammatory response can do this
they can also convert to SCV cells to tolerate antimicrobials
can staph aureus enter osteophytes?
yes as a SCV cell, which acts as a resivoir for pressitent infection. often when the host is compromised is when they revert back to staph aureus
if someone is immunocompromised what does that mean for infections
they are at high risk and their body is unlikely to provide large signs to show that there is an infection, more discrete signs
IV antibiotics is necessary when?
adults with two or more of the follow systemic symptoms of infection
-temp more than 38deg or less than 36 deg
-heart rate more than 90bpm
-respiratory rate more than 20 breaths a min
-white cell count more than 12 x 10^9 L or less than 4 x 10^9L
-contact GP and refer to hospital for IV
local signs of infection
tenderness
warmth
redness - erythema
swelling
probe to bone-osteomyelitis
if someone has an infected diabetic foot and youre deciding what antibiotics to use where would you go?
IWGDF guidelines
process of diabetic foot infection and antibiotic treatment
swab and send for MC and S
refer to gp for renal function, BGLs
consider medical history (allergies, drug interactions)
IWGDF guidelines based off degree of infection
-empiracal therapy
-directed therapy
refer to hospital if there is
-systemic signs of infection
-unresolving infection
-osteomyelitis
diagnosing osteomyelitis and monitoring
probe to bone test
bone biopsy- gold standard but rarely done
radiograph
blood tests
elevated:
-ESR
-CRP
-WCC
culture
monitoring -blood tests and renal function tests
IWGDF guidelines on determining if there is an infection
needs to have two of the following features
-local swelling/induration
-erythema extending more than 0.5
-local tenderness/pain
-local warmth
-purulent discharge
IWDGF gudelines on infection classification (mild, mod, sev)
mild- only the skin/subcutaneous tissue
erythema extends no more than 2cm
no systemic features
mod- involves structures deeper than skin/subcutaneous tissue (muscle, bone, tendon, joint) or erythema extends more than 2cm. no systemic features
sev- systemic inflammtory response syndrome
how long should antibiotic treatment take for mild/mod infection
duration: 1-2 weeks for mild/mod
-infection should be reolsved by this time but not wound
pathology results may change antibiotic treatment
key steps to assessing and treating an infection
- rule out serious pathology
-refer to hospital if theres signs of
septic arthritis
ostoemyleities
unresolving infection
severe infection that requires IV
systemic symptoms (2 or more signs) - is there signs of infection (2 or more)
- what degree of infection (mild, mod, sev)- wound?no wound?
- TG or IWGDF guidelines for treatment
- management
-swab
-GP blood tests to diagnose/monitor
-empiracal treatment based of EBP
-directed therapy
what type of antibiotic for mild, mod,sev dibetic foot infections
mild-oral
mod-IV
sev-IV
antimicrobial resistance types
- multi-drug resistant- non susceptible to 1 or more agents in 3 or more categories
- extensively drug resistant - non susceptible to 1 agent in all but less than 2 categories
- pan-drug ressitant - non susceptible to all approved anti microbial agents (eg pseudomonoas)
ways that selective pressure has caused evolution of bacteria
- indiscriminate use of antibiotics
- insufficient dosages
- insufficient length of courses
other ways resistance has occurred
- broad spectrum
- empiracal treatment without switching to narrow
- non compliance
- inadequate dosage/length
- easy access to prescription
- hospital/nursing homes allowing spread
- over exposure to antibiotics
- animal husbandry- antibiotics on farm animals
types of antimicrobial resistance in humans
- innate - species are naturally resistant
- acquired- bacteria that was once sensitive to a drug becomes resistant (gene codes for resistance is transferred from one bacterium to another by mutation or transfer genetic material)
mechanisms of antimicrobial resistance
- enzymes produced by bacteria destroy the drug
- bacterial cell walls become impermeable to a drug or rapidly removed
- drug binding sites within abcteria become altered
- alternative metabolic pathway in bacteria using enzymes not affected by the drug
How long do corticosteroids work for
Everyone responds differently but usually around a few weeks to just over a month
How do you store corticosteroids in clinic
S4 med-
Secure location
Room temperature
Only endorsed prescribers can access location
Documentations for purchasing for 2 years
