Optochin resistance inStreptococcus pneumoniae strains isolated from blood and middle ear fluid

Kontiainen, Sirkka; Sivonen, Aulikki

doi:10.1007/bf02013101

Cited by 53 publications

(29 citation statements)

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“…Susceptibility to optochin is a cornerstone in the phenotypic identification of pneumococci and is often used in laboratories as the primary and sometimes the only identification method (21). The occurrence of optochin-resistant S. pneumoniae strains, which can result from mutations in the H ϩ -ATPase (11), is not uncommon (2,10,21,25,26,28), jeopardizing the detection and correct identification of pneumococci.…”

Section: Discussionmentioning

confidence: 99%

“…The occurrence of optochin-resistant S. pneumoniae strains, which can result from mutations in the H ϩ -ATPase (11), is not uncommon (2,10,21,25,26,28), jeopardizing the detection and correct identification of pneumococci. Other problems with optochin susceptibility testing may be caused by alpha-hemolytic streptococci and aerococci, which show small zones of inhibition around optochin disks (23).…”

Section: Discussionmentioning

confidence: 99%

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Comparison of Five Genotypic Techniques for Identification of Optochin-Resistant Pneumococcus-Like Isolates

et al. 2003

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Three PCR techniques (amplification of the psaA, ply, and lytA genes) and a commercial kit (AccuProbe [GenProbe, San Diego, Calif.], based on hybridization with the 16S rRNA gene), all four of which claimed to be specific for Streptococcus pneumoniae, were used to identify 49 alpha-hemolytic streptococcal isolates suspected of being pneumococci. The definite phenotypic identification of these organisms as S. pneumoniae was difficult when optochin susceptibility and the presence of a capsule were taken as markers. Furthermore, RsaI digestion of the amplified 16S rRNA gene was applied. All 49 strains were optochin resistant. Eleven of these were encapsulated and were identified as pneumococci by all tests. Twenty of the 38 unencapsulated strains were unambiguously identified as nonpneumococci by all tests. The identities of another 18 unencapsulated strains remained inconclusive due to highly variable reactions for all phenotypic and genotypic techniques applied. The AccuProbe test was positive for seven strains for which the results of the other tests were inconclusive. RsaI restriction of the amplified 16S rRNA gene confirmed the AccuProbe result for all strains, while the result of the psaA-specific PCR was in concordance with encapsulation for all strains. The results presented here indicate that identification problems continue to exist for some strains, despite the application of genotypic and phenotypic tests in combination. We found the psaA-specific PCR to be the genotypic technique best suited for the identification of genuine pneumococci and optochin-resistant pneumococci.Optochin susceptibility and encapsulation are the phenotypic characteristics that are the most frequently used to differentiate between Streptococcus pneumoniae and other streptococci (22). However, optochin-resistant S. pneumoniae strains are being isolated more frequently (2, 29) and are probably largely overlooked, since in many laboratories primary isolation of pneumococci on culture medium relies on optochin susceptibility itself. The occasional occurrence of encapsulated S. mitis and S. oralis strains and the fact that nontypeable, unencapsulated pneumococci have been reported to comprise 2% of the isolates from normally sterile sites (3) and up to 20% of the conjunctival isolates (12) further complicate the identification of pneumococci. Commercial systems like the API 20S and Vitek2 systems occasionally fail to identify pneumococcal isolates or identify other streptococci as pneumococci (4). Thus, even though the phenotypic identification of typical pneumococci is unambiguous, the existence of optochin-resistant isolates may increasingly cause problems in clinical bacteriological laboratories.In the last decade, new gene amplification methods, based on the detection of pneumococcal virulence factors, have been developed to identify pneumococcal strains (18,23,24,34) and to detect pneumococci directly from clinical samples (8, 13, 14, 19, 31-33, 35, 36). Hybridization methods (10, 30) have also been used for the identification ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Comparison of Five Genotypic Techniques for Identification of Optochin-Resistant Pneumococcus-Like Isolates

et al. 2003

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“…Nevertheless, 30 years after the introduction of the Opt susceptibility test as a diagnostic tool (5), the first optochin-resistant (Opt r ) S. pneumoniae isolate was described (6). Since then, the isolation of Opt r S. pneumoniae from a variety of clinical sources has sporadically been reported from different locations, with an apparent increasing incidence in the last decade (2,3,7,8,9,10,11,12).…”

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confidence: 99%

Phenotypic and Molecular Characterization of Optochin-Resistant Streptococcus pneumoniae Isolates from Brazil, with Description of Five Novel Mutations in the atpC Gene

et al. 2013

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“…Optochin-resistant pneumococcal strains were first reported in Finland in 1987 (10), and since then, sporadic reports of isolates from diverse geographic areas have appeared in the literature (1,3,9,12,14,15). In particular, Aguiar et al have recently reported the emergence of optochin-resistant pneumococci in Portugal, which accounted for 3.2% of all clinical isolates recovered from 30 laboratories across the country (1).…”

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confidence: 99%

Optochin Resistance among Streptococcus pneumoniae Strains Colonizing Healthy Children in Portugal

2008

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Optochin resistance inStreptococcus pneumoniae strains isolated from blood and middle ear fluid

Cited by 53 publications

References 3 publications

Comparison of Five Genotypic Techniques for Identification of Optochin-Resistant Pneumococcus-Like Isolates

Comparison of Five Genotypic Techniques for Identification of Optochin-Resistant Pneumococcus-Like Isolates

Phenotypic and Molecular Characterization of Optochin-Resistant Streptococcus pneumoniae Isolates from Brazil, with Description of Five Novel Mutations in the atpC Gene

Optochin Resistance among Streptococcus pneumoniae Strains Colonizing Healthy Children in Portugal

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