CARTAGENA, Colombia (Reuters) - A prostitution scandal involving U.S. security personnel in Colombia and an unprecedented regional push to end the isolation of Cuba threatened on Saturday to eclipse President Barack Obama's charm offensive to Latin America.
              In a major 
embarrassment for Washington at the Summit of the Americas attended by 
more than 30 heads of state, 11 U.S. Secret Service agents were sent 
home and five military servicemen grounded over "misconduct" allegations
 in a hotel.
              Prostitutes were taken to the hotel, according to a Colombian police source.
              The widening 
controversy was overshadowing a host of weightier topics at the two-day 
summit that began on Saturday.