Quinolone Susceptibility in Salmonella Isolates Based on Minimum Inhibitory Concentration Determination

Introduction Typhoid fever, caused by Salmonella typhi and paratyphi , is a generalized infection with case fatality of about 10%. The symptoms may be severe, with life threatening sequelae of infection in a proportion of cases. Antimicrobial agents are the mainstay of therapy in enteric fever so as to prevent the complications associated with severe illness and mortality in the patients. Fluoroquinolones (e.g., ciprofloxacin) are very effective against completely susceptible Salmonella bacteria. However, their efficacy is doubtful once any resistance is detected. Pefloxacin testing has ultimately helped in the accurate identification of quinolone susceptibility for a better therapeutic success rate. In the present study we have tried to evaluate the quinolone susceptibility in Salmonella isolates based on minimum inhibitory concentration (MIC) determination. Materials and Methods  The method used in the study is quinolone susceptibility in Salmonella isolates based on MIC determination. Salmonella isolates show intermediate susceptibility to ciprofloxacin using disk diffusion. Both ciprofloxacin and pefloxacin MIC evaluation has been done to corroborate the results with pefloxacin disk diffusion testing. Results There was a positive correlation between the susceptibility to ciprofloxacin and pefloxacin. However, the isolates with intermediate susceptibility had variations in terms of susceptibility to pefloxacin. MIC values for pefloxacin and our findings suggested that pefloxacin susceptible on disk diffusion as per Clinical and Laboratory Standards Institute guidelines showed lower values for MIC using Pefloxacin HICOMB test and pefloxacin resistant isolates showed higher MIC values.