Occurrence of β-Lactamase-Producing Gram-Negative Bacterial Isolates in Water Sources in Cali City, Colombia.

These results indicate that β-lactamase-producing Gram-negative bacteria are widespread in the environment in the aquatic ecosystem of Cali city. The artificial and natural waters that cross the city are finally discharged into the Rio Cauca; this river can then be considered as a medium for the spread of bacterial antibiotic resistance genes.