Isolation, Characterization and Antibiotic Susceptibility Studies of Clinical Isolates of Steptocococcus mutans Obtained from Patients Visiting Major Dental Clinics in Nsukka, Nigeria

Abstract

The antibiotic susceptibility studies of clinical isolates of Streptococcus mutans obtained from dental patients was evaluated. The susceptibility patterns of the Streptococcus mutans isolates to a variety of antibiotics namely: Augmentin^R [Amoxicillin-clavulanic acid], amoxicillin, erythromycin, tetracycline, cotrimoxazole, chloramphenicol, gentamicin and cloxacillin were determined using the disc diffusion method.  In addition, the minimum inhibitory concentrations (MICs) of four selected antibiotics against the Streptococcus mutans isolates were determined. Finally the IZD₉₅, IZD₉₀ and IZD₅₀ were determined for all the antibiotics used. The Streptococcus mutans isolates were most susceptible to all the antibiotics except erythromycin with a percentage susceptibility of 0% using the break point IZD for susceptibility. Among the four selected antibiotics for MIC studies, gentamicin and cotrimoxazole had lower MIC values as low as 0.8700 and 1.3893 µg/ml respectively against these isolates, than amoxicillin and augmentin with values of 4.4045 and 6.3460 µg/ml respectively.The highest activity for IZD₉₅, IZD₉₀ and IZD₅₀ was recorded for the following antibiotics; amoxicillin, augmentin and augmentin respectively. Their order of activity was AMX _(IZD95)> AUG _(IZD90)>AUG _(IZD50).