Antibiotic Resistant Bacteria Isolated From The Monocacy River

Abstract

Twenty-two tetracycline (Te) resistant, gram-negative, rod-shaped bacteria were isolated from the Monocacy River in Frederick County, Maryland. Based on standard isolation procedures, this represents 0.2% of the bacterial populationisolated from the river water. The Te-resistant organisms were identified as P/Lovidencia 4tuantii (10 isolates), SuLtatia malice4cenz (7 isolates), and one isolate each of Ptoteuz vutganiz, Ezchetichia coti, Atcatigene4 odman4 and Acinetobactem_ catcoaceticuz. One additional Te-resistant isolate was identified tentatively as a member of the generaof EntelLobactet or Ha6nia. Supplementary antibiotic resistance testing on the Te-resistant isolates yielded varied resistance patterns; however, all exhibited a uniform resistance pattern to erythromycin, methicillin, novobioc in, penicillin and tetracycline. Curing with acridine orange suggested that the Te-resistance for single representative isolates of P. ztuattii, S. manceiscen4 (non-pigmented), E. coti and P. vutganiz were plasmid mediated. The same isolate of P. 4tuaAtii yielded six plasmids of the following approximate sizes; 3.2, 5.5, 8.9, 10.3, 29.4 and 39.8 kilobases (kb). Transformation of the standard strain E. coti HB101 with the isolated plasmid DNA (pDNA) from the P. 4tuctAtii isolate indicated that the Te-resistant marker resided in the 29.4 kb plasmid.