Bone and joint infections: Kingella kingae septic arthritis: practice question

A Orthopaedics question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Orthopaedics · Bone and joint infections: Kingella kingae septic arthritis

Sample item

A 2-year-old attending day care has had low-grade fever and a limp for three days. The knee is mildly swollen, the leucocyte count is near normal, and routine culture of the joint aspirate on solid media is sterile. Which organism, recovered best when aspirate is inoculated into blood-culture bottles, is a recognised cause at this age?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Kingella kingae

Kingella kingae is a fastidious Gram-negative organism that causes mild skeletal infections in children aged about 6 months to 4 years and is often missed on plates. Inoculating synovial fluid into blood-culture bottles or using PCR improves yield. Group B streptococcus and E. coli belong to the neonatal period.

Option by option

  • A. Group B streptococcus

    Group B streptococcus causes bone and joint infection in neonates and grows readily on standard media.

  • B. Haemophilus influenzae type b

    Haemophilus influenzae type b is now uncommon after conjugate vaccination and grows on standard media.

  • C. Escherichia coli

    Escherichia coli is a neonatal pathogen and grows readily on routine culture.

  • D. Kingella kingae (correct)

    Correct. It is a fastidious organism of young children, grown best in blood-culture bottles.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is D, Kingella kingae. Kingella kingae is a fastidious Gram-negative organism that causes mild skeletal infections in children aged about 6 months to 4 years and is often missed on plates.

Why is "Group B streptococcus" not the answer?

Group B streptococcus causes bone and joint infection in neonates and grows readily on standard media.

Why is "Haemophilus influenzae type b" not the answer?

Haemophilus influenzae type b is now uncommon after conjugate vaccination and grows on standard media.

Why is "Escherichia coli" not the answer?

Escherichia coli is a neonatal pathogen and grows readily on routine culture.

What concept does this question test?

It tests Bone and joint infections: Kingella kingae septic arthritis in Orthopaedics. Inoculating synovial fluid into blood-culture bottles or using PCR improves yield. Group B streptococcus and E. coli belong to the neonatal period.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Bone and joint infections: Kingella kingae septic arthritis?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.