Phenotypic susceptibility to antibiotics gram-negative bacteria in the middle Adriatic

Cilj ovog rada je ispitati fenotipsku osjetljivost na antibiotike gram-negativnih bakterija izoliranih sa šest postaja pod različitim antropogenim utjecajem u srednjem Jadranu (Kaštelanski zaljev, Kaštel Sućurac, Jadro, Splitski kanal, Vranjic i Stončica na otoku Visu). Ispitana je razina fekalnog onečišćenja na postajama i određena učestalost rezistencije na pet antibiotika (cefotaksim, azitromicin, tetraciklin, gentamicin i sulfometaksazol). Metodom disk-difuzije na Mueller-Hinton agaru utvrđena je fenotipska osjetljivost na 17 antibiotika kod 93 izolata, svrstanih u 9 porodica i 32 bakterijske vrste. Najveći broj izolata bio je rezistentan na cefoksitin (74,19 %) i cefotaksim (63,44 %), a najmanji na gentamicin (8,60 %), ciprofloksacin i kolistin (3,23 %). Učestalost rezistencije na postajama posljedica je sastava bakterijskih populacija, među kojima prevladavaju vrste s prirodnom rezistencijom na antibiotike. Rezultati ukazuju i na povezanost stupnja fekalnog onečišćenja sa stopom rezistencije, naročito za cefotaksim i tetraciklin na postajama Jadro i Kaštel Sućurac. Potrebna su daljnja istraživanja morskog ekosustava koji su pod antropogenim utjecajem u svrhu boljeg razumijevanja cjelokupnog širenja bakterijske rezistencije na antibiotike i smanjenja rizika za ljudsko zdravlje.The aim of this study was to examine the phenotypic susceptibility to antibiotics of gram-negative bacteria isolated from six stations under different anthropogenic influence in central Adriatic (Kaštela Bay, Kaštel Sućurac, Jadro, Split Channel, Vranjic and Stončica-Vis). The level of fecal contamination at the stations and the frequency of resistance to five antibiotics (cefotaxime, azithromycin, tetracycline, gentamicin, and sulfamethoxazole) were determined. The phenotypic susceptibility to 17 antibiotics for 93 isolates, classified into 9 families and 32 bacterial species, was determined by the disk diffusion method on Mueller-Hinton agar. The highest number of isolates was resistant to cefoxitin (74,19 %) and cefotaxime (63.44 %), and the lowest to gentamicin (8,60 %), ciprofloxacin and colistin (3,23 %). The frequency of resistance at stations is due to the composition of bacterial populations, among which species with intrinsic antibiotic resistance predominate. The results also indicate an association between the degree of fecal contamination and the resistance rate, especially for cefotaxime and tetracycline at Jadro and Kaštel Sućurac stations. Further research is needed on marine ecosystems that are under anthropogenic influence to better understand the overall spread of bacterial resistance to antibiotics and reduce the risk to human health