MSS Important Questions Flashcards
(438 cards)
[Old PP]
In diagnosis of tuberculous spondylitis, which investigation is MOST USEFUL clinically?
A. Biopsy of bone
B. Blood culture for acid-fast bacilli
C. Sputum for acid-fast bacilli
D. Tuberculin skin test
E. X-ray of spine
A
B, D: not specific to TB of bone
C: pulmonary TB
E: radiological diagnosis of spondylitis only, X microbiological diagnosis
[Old PP]
A cirrhotic patient develops symptoms of necrotising fasciitis. What is the most common causative agent?
A. Bacteroides
B. Klebsiella pneumoniae
C. Staphylococcus aureus
D. Vibrio cholerae
E. Vibrio vulnificus
C
[Old PP]
Which of the following is the earliest sign of necrotising fasciitis?
A. Blue discolouration
B. Blister formation
C. Local numbness
D. Local tenderness
E. Fever
D
Spreading edge: tender
Centre: anaesthetic later
Late: septic shock
[Old PP]
Which of the following is the most common cause of necrotising fasciitis?
A. Streptococcus agalactiae
B. Streptococcus dysgalactiae
C. Streptococcus iniae
D. Streptococcus pyogenes
E. Streptococcus bovis
D
Most common cause (type II - monomicrobial, streptococcal):
- GAS (most common) OR beta-hemolytic streptococci +/- others (e.g. S. aureus)
GBS: S. agalactiae
Group C/G: S. dysgalactiae
GDS: S. bovis, Enterococci (formerly) => rarely cause Type II necrotising fasciitis
Beta-hemolytic: GAS, GBS, Group C/G, S. iniae
Gamma-hemolytic: GDS
[Self-assessment]
Which layer of skin does impetigo involve?
Upper epidermis
[Self-assessment]
Which layers are involved in cellulitis?
Skin and subcutaneous tissue
[PP]
What is the most common pathogen involved in necrotising fasciitis following exposure to seawater?
Vibrio vulnificus
Type III necrotising fasciitis (monomicrobial)
1. Vibrio vulnificus
2. Aeromonas hydrophila (fresh / brackish water)
[PP]
Which of the following skin and soft tissue infections is characterised by a diffuse inflammation of the soft tissue without pus collections?
A. Carbuncle
B. Cellulitis
C. Furuncle
D. Impetigo
B
Lower extremities most involved
[PP]
A 57-year-old woman developed a rapidly progressive cellulitis of the thigh after a minor injury by a lobster at the fish market. What is the most likely pathogen(s) involved?
Vibrio vulnificus
Clues: seawater, raw or undercooked seafood e.g. shellfish
[PP]
Necrotising fasciitis of the trunk in a child following a recent episode of chickenpox. What is the most likely pathogen(s) involved?
Streptococcus pyogenes
Children who had chickenpox (varicella) are more likely to develop serious GAS infections, though uncommon.
[PP]
Dermatophytes are fungi that require keratin for growth and hence causes infection of skin and skin appendages. Which of the following fungi is a dermatophyte?
A. Aspergillus
B. Cryptococcus
C. Histoplasma
D. Trichophyton
D
Dermatophytosis / Ringworm / Tinea
1. Skin (stratum corneum) e.g. tinea pedis (athletes’s foot), tinea faciei, tinea corporis
2. Hair e.g. tinea capitis
3. Nail e.g. tinea unguium
Dermatophytes:
1. Epidermophyton floccosum
2. Trichophyton
3. Microsporum
[PP]
What is the most common pathogen involved in furuncle?
S. aureus
Other causative agents: Pseudomonas aeruginosa
[PP]
What is the most common pathogen involved in onychomycosis?
Dermatophytes (e.g. Trichophyton rubrum)
Non-dermatophyte moulds
Yeasts
(fungi)
[PP]
What is the most common pathogen involved in diaper rash?
Candida albicans
[PP]
Until a few years ago the inflammation in gout was thought to be due to mechanical damage by neutrophils. In recent years this view has changed. Outline the role of cathepsins (3 marks) and the inflammasome (2 marks) in the pathogenesis of gout.
- Monosodium urate crystals are phagocytosed by neutrophils.
- They are incorporated into phagosomes where they combine with cathepsins.
- Rupture of the membrane leads to cathepsin release.
& ROS production from mitochondria
=> dissociation of TXNIP from TRX-TXNIP complex
=> TXNIP activates NLRP3 inflammasome - The inflammasome is formed and activated.
- This leads to caspase activation and secretion of proinflammatory IL-1.
[PP]
Which of the following joint conditions has the greatest disease burden in the Hong Kong population?
A. Ankylosing spondylitis
B. Gout
C. Osteoarthritis
D. Rheumatoid arthritis
C
[PP]
A synovial biopsy from a 35-year-old lady shows a papillary architecture with increased lymphocytes and plasma cells in the stroma. What is the most likely diagnosis?
A. Ankylosing spondylitis
B. Gout
C. Osteoarthritis
D. Rheumatoid arthritis
D
Histology;
Papillary synovium with cell hyperplasia
Neovascularisation
Fibrin
Edema
Nodules of lymphocytes, plasma cells, mast cells
[PP]
A 55-year-old Chinese man presents with a well demarcated erythematous patch below his umbilicus. You suspect contact dermatitis to nickel. What type of hypersensitivity reaction does allergic contact dermatitis belong to?
Type 4 hypersensitivity reaction
[Old PP]
Joints can be classified according to the type of binding tissues that connect bones to each other. Which type of joint is pubic symphysis?
Secondary cartilaginous joint (immovable)
[Old PP]
Axis of femoral neck is at an angle of 8-14° with reference to transcondylar axis. What is the name of this angle which is important in maintaining hip stability and normal walking?
Angle of anteversion / femoral torsion
(inferior view) between line joining 2 femoral condyle & line along femoral neck
Measured by surgical transepicondylar axis
Too large
-> intoeing (excessive hip internal rotation)
[Old PP]
A patient had a deformity of hip where angle between neck and shaft of femur in frontal plane is decreased. Name this angle.
Angle of inclination
Between line along shaft & line along neck
Too large (>125°): coxa valga
Too small (<125°): coxa vara
[Old PP]
A school teacher has torn his medial meniscus in a skiing accident. What structure does medial meniscus bind to which makes it more prone to damage than lateral meniscus?
Tibial / Medial collateral ligament
Unhappy triad:
valgus (lateral) force injures
- ACL
- Medial meniscus
- MCL / tibial collateral ligament Unhappy triad
[Old PP]
Head and shaft of femur made an angle of 125°. What is the name of this angle?
Angle of inclination
Angle of anteversion / femoral torsion: 8-14°
[Old PP]
Which of the following statements most appropriately describes ligaments of knee joint?
A. ACL prevents posterior displacement of femur in relation to tibia.
B. ACL & PCL act synergistic to each other
C. LCL tear will most likely be associated with a tear in lateral meniscus.
D. Sudden change in direction at high speeds will likely cause PCL injury.
E. MCL resists force pushing from medial side.
A