Staphylococcus Aureus
Also written as MSSA.
Cavitation is typically due to Staphylococcus aureus (or TB).
What our notes say
- Cavitation is typically due to Staphylococcus aureus (or TB). (Paediatrics end of fourth year special supplementary exam: August 2019, Paper On)
- Staphylococcus aureus is now the commonest cause on native valves. (Paediatrics main exam (MBPE 4300): 24 January 2022, Paper One, 100 MCQs, 2 short)
- Right-sided endocarditis in people who inject drugs is commonly caused by Staphylococcus aureus and involves the tricuspid valve. (Cardiology Question Bank: 15 Clinical MCQs)
- Explain the differences between cellulitis and erysipelas caused by Staphylococcus aureus. (5 Marks) (Bacteriology and Entomology Main Exam)
- b) What is the typical epidemiology of this category of Staphylococcus aureus and how does it compare with MRSA that has been traditionally found in hospital settings. (FAIMSmicro 1 2006 — Past Paper Questions & Answers)
- | Flucloxacillin | Anti-staphylococcal penicillin | Staphylococcus aureus (septic emboli, post-influenza) | Cholestatic jaundice | (Lung Abscess)
Study material on Staphylococcus Aureus
- Medical Bacteriology and Entomology MCQs
- Respiratory system pathology mcqs
- Medical Bacteriology and Entomology
- MBPL3822 Chemotherapy CAT 1 MCQs
- Junior Clerkship in Internal Medicine (MBIM4100) main exam, Paper One: 31 January 2024
- Skin & Breast Pathology CAT: MKU Year 3 Medicine Exam
- Medical Bacteriology And Parasitology End Year 2024/2025
- Paediatrics end of second semester exam (MBPE 4300): 4 October 2022, cardiology, hepatology and gastroenterology, 47 of 50 MCQs
- Paediatrics main exam (MBPE 4300): 24 January 2022, Paper One, 100 MCQs, 2 short essays and 2 long essays
- Bacteriology and Entomology Main Exam
- Weekly Year 2: Microbiology Exam - June 12, 2026 (Section A: MCQs)
- Weekly Year 2: Microbiology Exam - May 15, 2026 (Sections B & C)
- Weekly Year 2: Microbiology Exam - April 21, 2026 (Section A: MCQs)
Practice questions on Staphylococcus Aureus
A 31-year-old man has a puncture wound to his thumb, which becomes secondarily infected with Staphylococcus aureus organisms. Which of the following functions is most likely to be served by lymphatics at the site of his injury to produce a specific immune response to these organisms?
- Carry lymphocytes to peripheral tissue sites
- Remove extravascular tissue fluid
- Transport antigen presenting cells
- Serve as a route for dissemination of infection
- Provide an emigration point for neutrophils
Answer: C. Antigen presenting cells such as dendritic cells and macrophages which have trapped antigen in peripheral tissues can be transported to lymph nodes where they encounter specific clones of memory cells capable of responding to those specific antigens, and this typically happens within a day. ---
An outbreak of sepsis caused by Staphylococcus aureus has occurred in the newborn nursery. What is the most likely source of the organism?
- Contaminated intravenous fluids
- Contaminated respiratory equipment
- Nasal carriage by healthcare workers
- A contaminated milk formula
Answer: C. Staphylococcus aureus is a common colonizer of the nasal passages. Healthcare workers with nasal carriage can transmit the organism to vulnerable newborns, leading to sepsis.
An outbreak of sepsis caused by Staphylococcus aureus has occurred in the newborn nursery. What is the most likely source of the organism?
- Nose
- Colon
- Hand
- Throat Answer:
Answer: A. The anterior nares are the classic carriage site (reservoir) for *S. aureus* in both patients and healthcare workers, and a common outbreak source in nurseries. --- ---
A 10-year-old child presents with fever and severe pain in the metaphysis of the tibia. Blood culture grows Staphylococcus aureus. Which diagnosis is most likely?
- Osteosarcoma
- Osteoid osteoma
- Pyogenic osteomyelitis
- Ewing sarcoma
- Chondroma ✅ Answer: A
Answer: A. Fever, severe pain in the metaphysis of a long bone, and positive blood culture for *Staphylococcus aureus* are classic signs of pyogenic osteomyelitis (C). Osteosarcoma (A) is a malignant tumor and does not typically present with fever or positive blood cultures.
An outbreak of sepsis caused by Staphylococcus aureus has occurred in the newborn nursery. You are called upon to investigate. According to your knowledge of the normal flora, what is the most likely source of the organism?
- Nose
- Colon
- Hand
- Throat
- Mostly unchanged in early disease
Answer: A. The anterior nares (nose) is the primary reservoir for S. aureus colonization, occurring in 20-40% of healthy adults. Healthcare workers can transmit the organism from their nose to patients via hands, making nasal carriage the most likely source in nosocomial outbreaks. ---
An outbreak of sepsis caused by Staphylococcus aureus has occurred in the newborn nursery. What is the most likely source of the organism?
- Nose
- Colon
- Hand
- Throat
- Primarily an incidental laboratory finding
Answer: A. S. aureus is commonly carried asymptomatically in the anterior nares (nose) of 20-40% of healthy individuals. Healthcare workers' nasal carriage is often the source of nosocomial outbreaks in nurseries. ---