QuestionSBA
QuestionChoice
This patient is infected with streptococcus pneumoniae, likely causing pneumonia and necessitating his admission. His history of bronchiectasis puts him at increased risk of developing respiratory infections. S. pneumoniae is a gram-positive diplococci, which is alpha-haemolytic, and optochin sensitive. Optochin testing tests specifically for s.pneumoniae - with optochin sensitivity indicating the presence of s.pneumoniae.
10006971
a
Streptococcus pneumoniae
QuestionChoice
Staphylococcus aureus is a gram-positive cocci. However, it would not respond to haemolysis testing and would not be optochin-sensitive. It would also not typically cause a respiratory infection (likely in this patient due to the history of bronchiectasis).
10006973
c
Staphylococcus aureus
QuestionChoice
Neisseria meningitidis is a cause of meningitis. However, there is no evidence supporting a diagnosis of meningitis in this patient. Neisseria is a gram-negative diplococci.
10006975
e
Neisseria meningitidis
QuestionChoice
Mycoplasma pneumoniae can cause pneumonia in rare cases. However, it is a short rod, and does not have a cell wall, and therefore is not visible on gram-staining.
10006974
d
Mycoplasma pneumoniae
QuestionChoice
Haemophilus influenzae is the second most common cause of pneumonia following S. pneumoniae. However, it is a gram-negative rod, and would not respond to haemolysis or optochin testing.
10006972
b
Haemophilus influenzae
Concept
Chapter
2693
4555
Pneumonia
Topic
194
Infectious Diseases
13941
A 69-year-old male patient on a respiratory inpatient ward with a past medical history of bronchiectasis has sputum cultures analysed. Cultures demonstrate gram-positive diplococci. The organism is found to be alpha-haemolytic and optochin sensitive.

What is the most likely organism which has been identified on the patient's sputum culture?
a