bacteria resistant to three or four different classes of antibiotics were found in shellfish exposed to municipal sewage effluents but appear to be absent in shellfish and water originating from unpolluted aquatic environments.
Repeat this setence, but with the correct capitalization.
Bacteria resistant to three or four different classes of antibiotics were found in shellfish exposed to municipal sewage effluents but appear to be absent in shellfish and water originating from unpolluted aquatic environments.