KMU Past Paper Practice
Topic 9 — Infectious Arthritis, Rheumatic Fever and Bone–Joint Infections
3rd Year MBBS • 20 A-Type Single Best Answer MCQs
MCQ 1
A 7-year-old child develops bacteremia followed by an acutely swollen knee. Which anatomical characteristic of the synovial membrane most facilitates entry of circulating organisms into the joint?
Rich vascular supply without a limiting basement membrane
The highly vascular synovium permits hematogenous organisms to enter the joint readily, initiating acute infectious synovitis.
MCQ 2
A child with untreated bacterial arthritis develops worsening pain despite no increase in the number of organisms recovered from the joint. Which local change most directly accelerates ischemic damage within the affected joint?
Increase in intra-articular pressure
Accumulating purulent fluid raises pressure inside the closed joint, compromises perfusion and adds ischemic injury to enzyme-mediated cartilage damage.
MCQ 3
A patient recovers from severe septic arthritis but the affected joint remains permanently immobile. Histology shows dense collagen bridging the opposing articular surfaces without mature bone formation. Which outcome has occurred?
Fibrous ankylosis
Organization of destructive inflammation by granulation tissue and collagen can fuse articular surfaces before later ossification produces bony ankylosis.
MCQ 4
A 28-year-old man with chronic hip infection develops a draining sinus. Several weeks later, the discharge becomes foul-smelling and the surrounding skin becomes acutely inflamed. Which additional process best explains this change?
Secondary pyogenic infection
A chronic tuberculous sinus may become secondarily infected by pyogenic organisms, producing increased warmth, erythema and purulent discharge.
MCQ 5
A patient with long-standing mycobacterial arthritis sustains a fracture after minor trauma. Imaging shows extensive destruction of the adjacent subchondral bone. Which mechanism best explains the fracture?
Granulomatous erosion weakening the bone
Chronic granulomatous inflammation progressively destroys cartilage and adjacent bone, reducing mechanical strength and permitting a pathological fracture.
MCQ 6
A 12-year-old boy with chronic tibial osteomyelitis has persistent drainage. Imaging shows an opening in the surrounding reactive bone through which pus reaches the skin. Which term describes this opening?
Cloaca
A cloaca is the channel or opening in the involucrum through which pus and necrotic material drain from chronic osteomyelitis.
MCQ 7
A 50-year-old man has had a draining sinus from chronic osteomyelitis for many years. The sinus margin becomes raised, ulcerated and bleeds on contact. Which complication should be suspected?
Squamous carcinoma in the sinus tract
Long-standing draining sinuses may undergo malignant epithelial transformation, classically to squamous-cell carcinoma.
MCQ 8
A febrile child has localized metaphyseal tenderness for two days. Plain radiographs show no definite abnormality, but clinical suspicion of osteomyelitis remains high. Which investigation is most useful for detecting early marrow involvement?
Magnetic resonance imaging
Early radiographs may be normal, whereas MRI can demonstrate marrow edema and associated soft-tissue extension at an earlier stage.
MCQ 9
A child with streptococcal pharyngitis develops fever and a diffuse erythematous rash due to widespread T-cell activation. Which bacterial product most directly causes this toxin-mediated effect?
Pyrogenic exotoxin
Streptococcal pyrogenic exotoxins can function as superantigens, producing widespread T-cell activation, fever and rash.
MCQ 10
A strain of Streptococcus pyogenes spreads rapidly through inflamed pharyngeal tissue by dissolving fibrin barriers. Which virulence factor mediates this effect?
Streptokinase
Streptokinase activates fibrinolysis, helping the organism break down fibrin barriers and spread through tissue.
MCQ 11
Pus from a streptococcal soft-tissue infection becomes less viscous as extracellular nuclear material is degraded. Which microbial factor is responsible?
Deoxyribonuclease
Streptococcal DNases digest extracellular DNA released from damaged cells, reducing pus viscosity and facilitating tissue spread.
MCQ 12
A child with acute rheumatic fever develops inflammation involving the valves, myocardium and pericardium. Which term best describes this cardiac pattern?
Pancarditis
Acute rheumatic fever may involve all three cardiac layers, producing endocarditis, myocarditis and pericarditis together.
MCQ 13
At autopsy, a patient with acute rheumatic carditis has small sterile vegetations on a valve. Where are these lesions most characteristically located?
Along the lines of leaflet closure
Rheumatic endocarditis produces small sterile verrucae along valve closure lines, unlike bulky destructive vegetations of infective endocarditis.
MCQ 14
A child with severe rheumatic carditis has small firm painless nodules over the elbows and spinous processes. Which interpretation is most appropriate?
They support systemic rheumatic inflammation
Subcutaneous nodules over extensor surfaces are a recognized manifestation of rheumatic fever and commonly accompany significant carditis.
MCQ 15
A child with suspected acute rheumatic fever has no audible murmur, but cardiac involvement remains clinically suspected. Which investigation can identify otherwise inapparent valvular inflammation?
Echocardiography
Echocardiography can detect valvular regurgitation and cardiac involvement even when auscultatory findings are subtle or absent.
MCQ 16
A patient with frontal sinusitis has impaired drainage through the frontal recess. Into which nasal passage do secretions normally pass?
Middle meatus
The frontal sinus drains through the frontal recess into the middle meatus, a region commonly affected by mucosal obstruction.
MCQ 17
A child with ethmoidal sinus infection develops painful swelling around the eye. Which anatomical relationship most directly permits this complication?
Ethmoidal cells are closely related to the orbit
The ethmoidal air cells lie between the nasal cavity and orbit, allowing infection to extend into orbital tissues.
MCQ 18
During nasal examination, a physician identifies the opening of the nasolacrimal duct beneath the lowest nasal concha. Which passage is being examined?
Inferior meatus
The nasolacrimal duct opens into the inferior meatus beneath the inferior nasal concha.
MCQ 19
A patient sustains injury to the superior nasal mucosa and subsequently loses the sense of smell. Which specialized region was most likely damaged?
Olfactory mucosa near the nasal roof
The olfactory epithelium occupies the superior nasal cavity near the roof, superior concha and upper septum.
MCQ 20
A patient with severe dryness of the mouth develops recurrent mucosal injury and dental infection. Loss of which normal function most directly contributed to this problem?
Salivary lubrication, buffering and antimicrobial defense
Saliva protects oral tissues by lubrication, buffering acids and providing antimicrobial activity; loss of these functions promotes dental and mucosal disease.