Evaluation of PCR primers to screen for Streptococcus pneumoniae isolates and β-lactam resistance, and to detect common macrolide resistance determinants

Pneumococcal isolates (n = 148) from various countries (mostly from the USA) were tested by a primer set for PCR. Thirty-eight (86.4%) of the 44 penicillin G-susceptible isolates (MIC ≤ 0.06 mg/L) had unaltered pbps, while six isolates (13.6%) had either one or two alterations in pbps. Of 47 penicillin G-resistant strains (MIC ≥ 2 mg/L), 41 isolates (87.2%) had all three pbps altered, six isolates (12.8%) had altered pbp1a + 2x. Various combinations of altered pbp were seen in penicillin G-intermediate isolates. Prevalence of macrolide resistance genes mef(A) and erm(B) in isolates was clearly reflected by their MICs. All isolates were positive for lytA. The primers were useful for screening for Streptococcus pneumoniae and β-lactam resistance, and for detection of common macrolide resistance determinants.