Microbiology Flashcards
most common organisms in MSK infections
Staph aureus
Streptococci
Coliforms
Common organisms in prosthetic joint infections
CoNS, proprionobacteria (diphtheroids)
less common but severe bugs
pseudomonas aeruginosa
kingella in under 5s
features of kingella
gram -ve
usually sensitive to amoxicillin
features of SIRS
2+ of
- temp >38
- HR>90
- Resp rate >20 or PaCO2 12000 or
- WCC >12000 or
what is septic arthritis
infection of the joint space
main organisms in septic arthritis
MSSA and Strep
Diagnosis in septic arthritis
arthroscopic washout/joint aspirate
Blood cultures
Treatment of septic arthritis
IV flucloxacillin
if
What is osteomyelitis
inflammation of bone and medullary cavity
what method of spread is most likely in acute osteomyelitis
haematogenous
Where is CoNS usually found
skin flora
what feature of CoNS infection makes it difficult to treat with antibiotics alone
biofilm
treatment of PJI
remove prosthesis and cement
what is necrotising fasciitis
acute and severe infection of the subcutaneous soft tissues
what is the clinical picture in necrotising fasciitis
pain disproportionately high to superficial inflammation
what causes Type 1 Necrotising fasciitis
anaerobes plus multiple other bacteria
what causes type 2 necrotising fasciitis
flesh eating bacteria
group A strep
treatment of necrotising fasciitis
surgical debridement
penicillin and clindamycin
what does penicillin do
kills actively multiplying bacteria in their exponential growth phase
what does clindamycin do
stops bacterial protein production
what bug causes gas gangrene
clostridium perfringens
features of clostridium perfringens
part of normal bowel flora
gram +ve strictly anaerobic rods
what causes gangrene crepitus
spore germination and accumulation of gas bubbles in tissue space
treatment of gas gangrene
urgent theatre debridement
high dose antibiotics - penicillin, metronidazole, hyperbaric oxygen
what bug causes tetanus
clostridium tetani
features of clostridium tetani
gram +ve strictly anaerobic rods
where is clostridium tetani found
spores found in soil, gardens, animal bites etc
features of tetanus
spastic paralysis
lock jaw
treatment of tetanus
anti-toxin (immunoglobulin), penicillin, metronidazole, surgical debridement, booster vaccine
What/When is the tetanus booster vaccine given
toxoid at 2/3/4m
antibiotics used for staphs and streps
flucloxacillin, vancomycin, clindamycin
antibiotics used for coliforms
gentamicin
cephalosporin like ceftriaxone
sometimes ciprofloxacin
which bacteria are phenotypically resistant to antibiotics
bacteria in abscesses and biofilm
what is the protocol for surgical prophylaxis
first dose given within 60mins of start of surgery, it should not be continued >24hr after surgery
prophylaxis in orthopaedics
co-amoxiclav 1.2g peri-op and 2 post-op doses
when do most cases of acute osteomyelitis occur
post-traumatic or in open fractures
may also occur in children or the immunosuppressed
common organism to infect kids
haemophilus
what causes osteomyelitis
trauma causing blood vessel wall damage which acts as a petri dish for passing bacteria
what is an involucrum
new bone which forms around central dead bone
most common site for chronic osteomyelitis
tibia
how is gas seen on xray
little dark spots
what does necrotising fasciitis cause?
surgical emphysema
what bug usually causes discitis
staph
common bugs which infect arthroplasty
staph aureus, staph epidermidis
