Microbiology Flashcards
Which colour do gram-positive bacteria stain?
Purple/blue
Which colour do gram-negative bacteria stain?
Pink
Is staphylococcus gram-positive or negative?
Gram-positive
Which staphylococcus bacteria is coagulase positive?
Staph. aureus
golden border in petri dish
Which antibiotic is used against staph. aureus?
Flucloxacillin
Which toxins can be produced by staph. aureus?
Enterotoxin
SSSST
PVL
What is osteomyelitis?
Inflammation of the bone and medullary cavity, usually located in one of the long bones?
Which bacteria commonly cause osteomyelitis in newborns and children?
Staph. aureus
Group B strep
Which bacteria commonly causes osteomyelitis in adults?
Staph. aureus
What is the gold standard investigation for osteomyelitis?
Bone biopsy
Which classification system is used in osteomyelitis?
Gustilo Classification
Which investigations are used for diabetic foot ulcers?
Plain radiograph
MRI
What is the treatment for diabetic foot?
Debridement
Antimicrobials
Which antibiotic is used in diabetic foot ulcer?
Flucloxacillin (IV)
MRSA cases = Doxycycline in mild and Vancomycin in moderate-severe cases
Severe cases - Flucloxacillin + Metronidazole
Why is oral doxycycline used instead of oral flucloxacillin when switching from IV to oral medication is osteomyelitis?
Flucloxacillin has poor bone penetration
Who is at risk of haematogeneous osteomyelitis?
Prepubertal children
PWID
Patients with central lines/dialysis
Elderly
Special conditions (e.g. sickle cell disease)
Which bone does Gaucher’s disease typically affect?
Tibia
What are the signs and symptoms of vertebral osteomyelitis?
Insidious pain and tenderness
Fever
Raised inflammatory markers
How is vertebral osteomyelitis treated?
Drain large paravertebral/epidural abscesses
Antimicrobials for 6 weeks minimum
What is Pott’s disease?
Vertebral tuberculosis
Is vertebral TB infectious?
No
What are some risk factors for infection in prosthetic joints?
Presence of comorbidities (e.g. rheumatoid arthritis, diabetics mellitus, malignancy)
Use of corticosteroids, TNF inhibitors
Prior arthroplasty or prior infection at the surgical site
Prolonged duration of surgery
Postoperative complications (e.g. haemato,a)
What is a biofilm?
A microbe-derived sessile community
Characterised by cells that are attached to a substratum, interface or each other.
The cells are embedded in a matrix of extracellular polymeric substance and exhibit an altered phenotype.
Which bacteria are msot commonly involved in prosethetic joint infections?
Staph. aureus
Staph. epidermidis
Cuttibacterium acnes (upper limb)
E. coli
pseudomonas aeruginosa
How are prosthetic joint infectios diagnosed?
Culture - perioperative tissue
Blood culture
CRP
Radiology
How is prosthetic joint infection treated?
Debridement
Antibiotics
Irrigation
Retention of the prosthesis
How is septic arthritis treated?
Flucloxacillin (high doses)
Less than 5 years old - add Ceftriaxone (for H. influenzae cover)
Which bacteria causes septic arthritis?
Staph. aureus
Which bacteria commonly causes pyomyositis?
Staphylococcal bacteria
What are some risk factors for pyomyositis?
IDU
Diabetes Mellitus
Contaminated wounds
What is pyomyositis?
A primary skeletal muscle abscess.
Associated with fever, muscle swelling and pain.
More common in tropical and sub-tropical regions.
What is myonecrosis?
Acute invasion of healthy tissue that can occur spontaneously or as a result of traumatic injury.
What is the treatment for myonecrosis?
Treatment surgery
AND
Antibiotics ( clindamycin + penicillin for clostridium)
Which bacteria causes tetanus?
Clostridium tetani
Which type of bacteria are clostridium tetani?
Gram-positive anaerobic rods
Spores found in soil, gardens etc.
What are the signs/symptoms of tetanus?
Lock jaw
Trismus
Risus sardonicus
Muscle spasm
What causes spastic paralysis in tetanus infection?
Neurotoxin release
Which investigations are used to diagnose tetanus?
Serum and urine toxin assays
How is tetanus treated?
Surgical debridement
Antitoxin
Supportive measures
Antibiotics for 7-10 days ( Penicillin, Metronidazole)
Booster vaccination
