Question

A child presents with sepsis. The bacteria isolated showed beta hemolysis on blood agar, resistance to bacitracin, and a positive CAMP test. The most likely organism is:

• A. Streptococcus agalactiae (Group B Streptococcus)
• B. Streptococcus pyogenes (Group A Streptococcus)
• C. Streptococcus pneumoniae
• D. Enterococcus faecalis

Hint:

Beta hemolytic, bacitracin resistant, CAMP positive equals Group B Streptococcus.

Answer 1

The Correct Option is A

Note: The block file truncated this stem and gave no printed key. The reconstructed lab profile (beta hemolytic, bacitracin resistant, with the classic CAMP reaction in a septic child) points clearly to Group B Streptococcus, so options and answer are filled from standard microbiology.
Step 1: Beta hemolysis on blood agar narrows the list to Group A and Group B streptococci among the common pyogenic cocci.
Step 2: Bacitracin sensitivity separates them. Group A Streptococcus (S. pyogenes) is bacitracin sensitive, while Group B Streptococcus (S. agalactiae) is bacitracin resistant. The isolate here is bacitracin resistant, which fits Group B and rules out S. pyogenes.
Step 3: The CAMP test is positive for Group B Streptococcus. S. agalactiae produces the CAMP factor, which enhances the hemolysis of Staphylococcus aureus and gives an arrowhead zone. This confirms Group B.
Step 4: Clinical fit. Group B Streptococcus is the leading cause of neonatal and early infant sepsis and meningitis, which matches a child presenting with sepsis.
Step 5: Why the others are wrong. S. pyogenes is bacitracin sensitive and CAMP negative. S. pneumoniae is alpha hemolytic and optochin sensitive. Enterococcus is usually non hemolytic or alpha and is bile esculin and salt tolerant, not CAMP defined.
Conclusion: The organism is Streptococcus agalactiae, option A.