Prevalence and diversity of extended-spectrum-β-lactamase-producing Enterobacteriaceae from marine beach waters

Abstract A total of 1351 Enterobacteriaceae isolates from 144 seawater samples were collected over a four-year period from three public beaches in the eastern Adriatic Sea in Croatia. Approximately 35% of the strains were multidrug-resistant. Bla ESBL genes were detected in 4.2% of the isolated Enterobacteriaceae , the main species of which were Escherichia coli , Enterobacter cloacae and Klebsiella pneumoniae. Bla TEM-1+SHV-12 was the most dominant genotype, followed by bla CTX-M-15. Raoultella terrigena and E. intermedius simultaneously harboured bla TEM-1, bla SHV-11/12 and bla CTX-M-15 . Isolate fingerprinting revealed that marine E. coli isolates were clonally related to CTX-M-producing strains from a regional university hospital. These results indicate that marine beach waters are reservoirs of ESBL-producing Enterobacteriaceae and thus constitute a public health problem with further potential to act as mediators in gene flow between marine coastal areas and clinical settings.