CASE HISTORY Marianna and Julio,two Children in Oklahoma Aged 8 and 11,fell

Essay

CASE HISTORY
Marianna and Julio,two children in Oklahoma aged 8 and 11,fell ill with food poisoning after consuming commercially canned hot dog chili sauce.The children complained of double vision and an inability to move their facial muscles.
Examination showed normal vital signs,symmetrical weakness (equal on right and left sides),and fixed pupils due to cranial nerve palsy (paralysis).Upper body paralysis gradually spread downward,and breathing became labored.
Botulinum toxin was identified in their blood by fluorescent monoclonal antibodies (antibodies produced by a genetically uniform cell culture).
The children were placed on mechanical ventilation (a machine that assists breathing)and treated with botulinum antitoxin.After several days,the children were removed from mechanical ventilation.They underwent physical rehabilitation for a full recovery.
The chili sauce was traced to a canning facility where six swollen cans tested positive for botulinum toxin A.From the cans,inspectors cultured a bacterium that grew only without oxygen,as in a closed can.A microscope showed that the bacterium had a distinctive club-shaped appearance.The bacterium was Clostridium botulinum,which produces botulinum toxin,the cause of botulism.One end of the club-shaped cell contains an endospore,an inert form of the cell that can germinate and grow in a closed container of food.Growing cells produce botulinum toxin,leading to botulism,a life-threatening form of paralysis.Microscopy of the pathogen's unique form confirms the identification.
Why was fluorescence microscopy used to help identify the causative agent of the children's disease,rather than bright field?