Evidence of gyrA mutations in nalidixic acid-resistant Salmonella enterica serotype Enteritidis

Abstract

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 qui-nolone 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.