Detection of antibiotic resistant bacteria inhabiting the sand of non-recreational marine beach.

The present study examined the antibiotic resistance of heterotrophic bacteria, which were isolated from the sand of the beach located in the National Park of the southern Baltic Sea coast. The bacteria demonstrated low levels of antibiotic resistance. These microorganisms were the most resistant to cefaclor and clindamycin and the most sensitive to clarithromycin, doxycycline, gentamycin and oxytetracycline. The majority of bacteria inhabiting the sand of the studied beach were resistant to only one antibiotic out of 18 tested antibiotics in this study. The bacteria inhabiting the middle part of the beach and the dune were more antibiotic resistant than bacteria isolated from the seawater and the shoreline-seawater contact zone. Generally, there was no significant difference in antibiotic resistance between bacteria isolated from the surface and the subsurface sand layers. The bacterial antibiotic resistance level depends on the chemical structure of antibiotics.

Bacterial pollution of the riverine surface microlayer and subsurface water.

The density and distribution of bacteria indicative of pollution in the surface microlayer and subsurface water of the River Slupia were estimated. The number of heterotrophic bacteria, total coliforms, fecal coliforms and fecal streptococci were higher in the surface microlayer than in the underlying water. The average bacterial enrichment factor (EF) of the parameters studied in the bacterioneuston was 1.7 to 1.8 times higher than in bacterioplankton. During the annual study cycle, bacterial pollution indicators inhabiting the surface microlayer and subsurface water showed considerable monthly changes.