ABSTRACT
A total of 1042 strains of Streptococcus mutans and Streptococcus sobrinus isolated between 1985 and 1989 were tested to study the evolution of their sensitivity to penicillin, amoxycillin, amoxycillin/clavulanic acid, cefuroxime, tetracycline, erythromycin, spiramycin, acetyl spiramycin, lincomycin and clindamycin. The strains were taken from stock cultures and isolated from human saliva and dental plaque. The minimal inhibitory concentration (MIC) was determined by an agar dilution method. Except for spiramycin and acetyl spiramycin, all the antibiotics inhibited 100% of the strains with concentrations less than or equal to 2 micrograms/ml. Microorganisms from both species underwent a slow progressive loss of sensitivity to all the antibiotics over a 5-year period of study, showing statistically significant results in most cases.
Subject(s)
Drug Resistance, Microbial , Streptococcus mutans/drug effects , Streptococcus sobrinus/drug effects , Dental Plaque/microbiology , Humans , Penicillin Resistance , Tetracycline ResistanceABSTRACT
Using the Vitek card for identification of gram-positive agents, 244 strains of Streptococcus agalactiae were studied. Twenty five out of these strains were studied during 3 consecutive days. The study also involved 25 pairs of maternal and neonatal strains. The system gave correct identification of only 52 out of 244 strains of S. agalactiae. Due to the low reproducibility of the system it is suggested that the bionumbers used in the codification of a microorganism should be avoided.
Subject(s)
Bacterial Typing Techniques , Reagent Kits, Diagnostic , Streptococcal Infections/microbiology , Streptococcus agalactiae/isolation & purification , Evaluation Studies as Topic , Humans , Species SpecificityABSTRACT
A methotrexate-containing medium for the detection of beta-hemolytic group B streptococci from clinical specimens on the basis of detection of pigment is described. The medium contained peptone, starch, serum, MgSO4, glucose, pyruvate, methotrexate (as pigment enhancer), phosphate-morpholine-propanesulfonic acid buffer, and selective agents. The recovery of beta-hemolytic group B streptococci was comparable to that obtained with selective broth.