Genotypic Survey of Recent β-Lactam-Resistant Pneumococcal Nasopharyngeal Isolates from Asymptomatic Children in Chile

Abstract

To assess pneumococcal strain variability among young asymptomatic carriers in Chile, we used serotyping, antibiotic susceptibility testing, and genotyping to analyze 68 multidrug-resistant pneumococcal isolates recovered from 54 asymptomatic children 6 to 48 months of age. The isolates represented capsular serotypes 19F (43 isolates), 14 (14 isolates), 23F (7 isolates), 6B (3 isolates), and 6A (1 isolate). Genotypic analysis, which included pulsed-field gel electrophoresis (PFGE) of chromosomal digests, penicillin binding protein (PBP) gene fingerprinting, and dhf gene fingerprinting, revealed that the isolates represented six different genetic lineages. Clear circumstantial evidence of capsular switching was seen within each of four of the genetically related sets. The majority of the isolates, consisting of the 43 19F isolates and 2 type 6B isolates, appeared to represent a genetically highly related set distinct from previously characterized pneumococcal strains. Each of three other genetically defined lineages was closely related to one of the previously characterized clones Spain 6B -2, France 9V -3, or Spain 23F -1. A fifth lineage was comprised of four type 23F isolates that, by the techniques used for this study, were genetically indistinguishable from three recent type 19F sterile-site isolates from the United States. Finally, a sixth lineage was represented by a single type 23F isolate which had a unique PFGE type and unique PBP and dhf gene fingerprints.

Penicillin-binding protein genotyping of penicillin-nonsusceptible Streptococcus pneumoniae isolates from the nasopharynx of healthy preschool children

“…Similar conclusions were reached by Sogstad et al [19], based on PBP analysis with an indication of the PBP2x determinant. Consistent with other studies [10,23], we have found reduced profile variation in the PBP genes among the majority of β-lactam-sensitive isolates.…”

Computational Studies on the Resistance of Penicillin‐Binding Protein 2B (PBP2B) of Wild‐type and Mutant Strains of Streptococcus pneumoniae Against β‐Lactam Antibiotics

“…The strains selected for this study, namely R6, 5204, G54, Hungary19A‐6, and SP195 have MIC values of penicillinG as <0.016 μg/mL (14,20), 6 μg/mL (14,20), 2–4 μg/mL (45), <1 μg/mL (46) and <1 μg/mL (46) respectively. According to penicillin, MIC range that ≤0.06 as susceptible, 0.12–1 as intermediate resistant, and >1 as highly resistant (20).…”

Molecular Epidemiology of Penicillin-Nonsusceptible Streptococcus pneumoniae among Children in Greece

“…In addition, novel drug-resistant clones have been reported in France, former Czechoslovakia, Spain, Hungary, Japan, South Africa, the United States, Chile, England, etc. which tend to spread in a nationwide manner (6,13,16,17,19,35,37,45). The risk for colonization with and spread of antibiotic-resistant strains is related to younger-age children, occurrence of refractory middle ear infections, previous antibiotic consumption, and day care attendance (9,28,32).…”