EVIDENCE OF gyrA MUTATIONS IN NALIDIXIC ACID- RESISTANT SALMONELLA ENTERICA SEROTYPE ENTERITIDIS

The goal of our research was to detect mutations on gyrA gene in a small collection of Salmonella enterica serovar Enteritidis (S. Enteritidis) isolated from stool specimens, food and poultry in quinolone resistant strains. Out of 60 randomly selected isolates, resistance to nalidixic acid was exhibited by 15%. Five isolates were from poultry, three isolates were from stools and one was found in a pastry collected from a biscuit factory. Polymerase chain reaction and sequencing revealed different mutations in gyrA gene. The following amino acid exchanges were found: Asp87Asn (in three isolates from stool and four isolates from poultry), Ser83Phe mutation was found in one isolate from poultry and Asp87Gly substitution was detected in one isolate from food. Multiple resistance in S. Enteritidis from a day-old chicken was attributed to ampicillin, cephalothin, nalidixic acid and tetracycline. In two strains from human stools the following resistotypes were noted: ampicillin, tetracycline, trimethoprim-sulfamethoxazole and ampicillin, tetracycline, trimethoprim-sulfamethoxazole and neomycin. This was the first research on distribution of gyrA mutations in S. Enteritidis in Serbia.