A 28-year-old woman from West Bengal presents with severe watery diarrhea and dehydration following consumption of contaminated water 16 hours ago. Stool culture on TCBS agar yields colonies that are oxidase-positive, ferment sucrose, and produce a positive string test (cells elongate and move together when mixed with specific antiserum). Biochemical testing shows the organism is Gram-negative, curved rod, and produces acid from glucose and sucrose but not from arabinose. The patient's serum shows vibriocidal antibodies. Which serotype of Vibrio cholerae is most likely responsible for this infection, and what is the clinical significance of the serotype in terms of pandemic potential?