MCQ of the Day: 10 November 2026

Answer: C. Streptococcus agalactiae (Lancefield group B streptococcus, GBS). GBS colonises the maternal genital tract and is a leading cause of early-onset neonatal sepsis, pneumonia and meningitis. It forms narrow-zone beta-haemolytic colonies, is bacitracin resistant and PYR negative, hydrolyses hippurate and is CAMP positive: its CAMP factor completes lysis of sheep red cells already damaged by staphylococcal beta-lysin, giving the arrowhead. Group B antigen testing confirms it.

A. Streptococcus pyogenes (group A) is usually bacitracin sensitive and PYR positive, with a wider zone of haemolysis.

B. Listeria monocytogenes is also CAMP positive and causes neonatal sepsis, but it is a catalase-positive Gram-positive bacillus with tumbling motility, not a coccus in chains.

D. Enterococcus faecalis is PYR positive, grows in 6.5% NaCl and hydrolyses aesculin in bile; it is usually non-haemolytic and CAMP negative.