title: Capsular transformation of a multidrug-resistant Streptococcus pneumoniae in vivo.
abstract: Several multidrug-resistant (MDR) isolates of Streptococcus pneumoniae recovered from a variety of clinical sources and expressing serotypes 9N, 14, 19F, and 3 could not be distinguished from the capsular type 23 Spanish/USA epidemic clone in antibiotype, pulsed-field gel electrophoretic pattern, and restriction fragment length polymorphism types of their penicillin binding protein genes 1A, 2X, and 2B. When tested in a mouse model of virulence, isolates expressing capsular type 3 were lethal for 100% of infected animals within 2 days after intraperitoneal injection of 10(2) cfu/mouse. In contrast, several capsular type 23F isolates belonging to the MDR Spanish/USA clone and recovered from the same site were not lethal, even when injected at the dose of 10(7) cfu/mouse. These data suggest that the pneumococcal isolates expressing serotypes 9N, 14, 19F, and 3 represent products of in vivo capsular transformation events in which the MDR epidemic capsular type 23F Spanish/USA clone was the recipient.
authors.affiliation: Laboratory of Microbiology, Rockefeller University, New York, New York 10021, USA.
authors.forename: M
authors.initials: M
authors.lastname: Nesin
authors.forename: M
authors.initials: M
authors.lastname: Ramirez
authors.forename: A
authors.initials: A
authors.lastname: Tomasz
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000235:genetics*; D004269:DNA, Bacterial; D018432:Drug Resistance, Multiple / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D051379:Mice; D008826:Microbial Sensitivity Tests; D012150:Polymorphism, Restriction Fragment Length; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D014169:Transformation, Bacterial
chemical_list: D004269:DNA, Bacterial