{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T23:58:29Z","timestamp":1775174309132,"version":"3.50.1"},"reference-count":42,"publisher":"Microbiology Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2006,2,1]]},"abstract":"<jats:p>The authors aimed to get insights into the population structure of non-(sero)typable pneumococci (NTPn), a specific group of natural atypical pneumococci whose identification is often difficult, and which has remained insufficiently studied. A total of 265 presumptive NTPn, isolated between 1997 and 2003 from the nasopharynx of children, were characterized. Strains were confirmed to be pneumococci on the basis of bile solubility, and PCR detection or Southern blotting hybridization of<jats:italic>lytA<\/jats:italic>and<jats:italic>psaA<\/jats:italic>, genes ubiquitous in this species. Multilocus sequence typing (MLST) was used to exclude two isolates that gave ambiguous results. Non-typability was confirmed by the Quellung reaction using Omniserum. A total of 213 isolates were considered to be true NTPn. The molecular analysis of the true NTPn by PFGE and MLST showed that this population was genetically diverse, although a dominant cluster, accounting for 66\u200a% of the isolates, was identified. Antimicrobial resistance was observed in most genetic backgrounds, and multidrug resistance to penicillin, erythromycin, clindamycin, tetracycline and sulfamethoxazole-trimethoprim was associated with strains belonging to the dominant cluster. Comparison with PFGE fingerprints and sequence types of large collections of serotypable strains showed that the genetic backgrounds of all but two NTPn were different from those found in serotypable strains. In addition, we found that NTPn strains with similar genetic backgrounds to those identified in our study had been isolated from disease sources in other countries. These observations seem to indicate that NTPn have diverse genetic backgrounds and may have evolved as a distinct group of pneumococcal isolates.<\/jats:p>","DOI":"10.1099\/mic.0.28596-0","type":"journal-article","created":{"date-parts":[[2006,1,25]],"date-time":"2006-01-25T06:22:47Z","timestamp":1138170167000},"page":"367-376","source":"Crossref","is-referenced-by-count":40,"title":["Identification, prevalence and population structure of non-typable Streptococcus pneumoniae in carriage samples isolated from preschoolers attending day-care centres"],"prefix":"10.1099","volume":"152","author":[{"given":"Raquel","family":"S\u00e1-Le\u00e3o","sequence":"first","affiliation":[{"name":"Molecular Genetics Laboratory, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica da Universidade Nova de Lisboa, Rua da Quinta Grande, 6, 2780-106 Oeiras, Portugal"}]},{"given":"Alexandra S.","family":"Sim\u00f5es","sequence":"additional","affiliation":[{"name":"Molecular Genetics Laboratory, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica da Universidade Nova de Lisboa, Rua da Quinta Grande, 6, 2780-106 Oeiras, Portugal"}]},{"given":"S\u00f3nia","family":"Nunes","sequence":"additional","affiliation":[{"name":"Molecular Genetics Laboratory, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica da Universidade Nova de Lisboa, Rua da Quinta Grande, 6, 2780-106 Oeiras, Portugal"}]},{"given":"Natacha G.","family":"Sousa","sequence":"additional","affiliation":[{"name":"Molecular Genetics Laboratory, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica da Universidade Nova de Lisboa, Rua da Quinta Grande, 6, 2780-106 Oeiras, Portugal"}]},{"given":"Nelson","family":"Fraz\u00e3o","sequence":"additional","affiliation":[{"name":"Molecular Genetics Laboratory, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica da Universidade Nova de Lisboa, Rua da Quinta Grande, 6, 2780-106 Oeiras, Portugal"}]},{"given":"Herm\u00ednia","family":"de Lencastre","sequence":"additional","affiliation":[{"name":"Laboratory of Microbiology, The Rockefeller University, NY, USA"},{"name":"Molecular Genetics Laboratory, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica da Universidade Nova de Lisboa, Rua da Quinta Grande, 6, 2780-106 Oeiras, Portugal"}]}],"member":"345","reference":[{"key":"R1","doi-asserted-by":"crossref","first-page":"4039","DOI":"10.1128\/JCM.37.12.4039-4041.1999","article-title":"Genetic relatedness among nontypeable pneumococci implicated in sporadic cases of conjunctivitis","volume":"37","author":"Barker","year":"1999","journal-title":"J Clin Microbiol"},{"key":"R2","doi-asserted-by":"crossref","first-page":"1694","DOI":"10.1128\/JCM.43.4.1694-1698.2005","article-title":"Analysis of the genetic structure of nontypeable pneumococcal strains isolated from conjunctiva","volume":"43","author":"Berron","year":"2005","journal-title":"J Clin Microbiol"},{"key":"R3","doi-asserted-by":"crossref","first-page":"2378","DOI":"10.1128\/JCM.41.6.2378-2384.2003","article-title":"Serotyping Streptococcus pneumoniae by multiplex PCR","volume":"41","author":"Brito","year":"2003","journal-title":"J Clin Microbiol"},{"key":"R4","doi-asserted-by":"crossref","first-page":"1424","DOI":"10.1086\/374624","article-title":"Clonal relationships between invasive and carriage Streptococcus pneumoniae and serotype- and clone-specific differences in invasive disease potential","volume":"187","author":"Brueggemann","year":"2003","journal-title":"J Infect Dis"},{"key":"R5","doi-asserted-by":"crossref","first-page":"4415","DOI":"10.1128\/JCM.41.9.4415-4417.2003","article-title":"Confirmation of nontypeable Streptococcus pneumoniae -like organisms isolated from outbreaks of epidemic conjunctivitis as Streptococcus pneumoniae","volume":"41","author":"Carvalho","year":"2003","journal-title":"J Clin Microbiol"},{"key":"R6","first-page":"1","article-title":"Preventing pneumococcal disease among infants and young children. 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