Figure. Number of erythromycin-resistant blood and cerebro- spinal fluid isolates of pneumococci. DNA was extracted from pneumococcal isolates by using a lysis solution consisting of 0.1% sodium deoxycholate as described in (11), except that we used plate rather than broth cultures. Seventy-eight MLS strains were probed for the ermAM gene by using dot blots. The probe (supplied by P. Courvalin, Pasteur Institute, Paris, France) (Escherichia coli JM83/pUC19 560bp Ssp1 intragenic fragment of ermB) was labeled with digoxygenin by using random primed labeling (DIG DNA Labeling and Detection Kit; Boeringer, Mannheim, Germany). Hybridization and detection were performed following manufacturer's instructions (DIG DNA Labeling and Detection Kit; Boeringer, Mannheim, Germany). PCR was also used to detect ermAM in 30 strains according to standard conditions, with an annealing temperature of 58°C. We used the following primers: forward primer, 5'-CGAGTGAAAAAGTACTCAACC, reverse primer, 5'-GGCGTGTTTCATTGCTTGATG). Published primers for the mefE gene (5'-AGTATCATTAATCACTAGTGC, and 5'-TTCTTCTGGTACTAAAAGTGG) (12) were used to detect mefE through PCR amplification in 13 M strains. Amplification was performed in a Perkin Elmer Cetus DNA Thermal Cycler under standard reaction conditions, with an annealing temperature of 56oC.
The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.