Antimicrobial susceptibility patterns and macrolide resistance genes of viridans group streptococci from blood cultures in Korea

Uh, Young; Shin, Dong Hoon; Jang, In Ho; Hwang, Gyu Yel; Lee, Mi Kyung; Yoon, Kyung Joong; Kim, Hyo Youl

doi:10.1093/jac/dkh219

Cited by 26 publications

(15 citation statements)

References 7 publications

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“…Although antimicrobial resistance is an increasing problem with many bacterial groups (43,44), SAG remain susceptible to most antibiotic classes, as was observed in the present study. The only significant resistance found was to clindamycin, erythromycin, and tetracycline.…”

Section: Discussionsupporting

confidence: 72%

Comparing Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Phenotypic and Molecular Methods for Identification of Species within the Streptococcus anginosus Group

et al. 2015

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The heterogeneity of members of the Streptococcus anginosus group (SAG) has traditionally hampered their correct identification. Recently, the group was subdivided into 6 taxa whose prevalence among human infections is poorly described. We evaluated the accuracy of the Rapid ID32 Strep test, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and a PCR multiplex method to identify 212 SAG isolates recovered from human infections to the species and subspecies level by using multilocus sequence analysis (MLSA) as the gold standard. We also determined the antimicrobial susceptibilities of the isolates. Representatives of all SAG taxa were found among our collection. MALDI-TOF MS and the Rapid ID32 Strep test correctly identified 92% and 68% of the isolates to the species level, respectively, but showed poor performance at the subspecies level, and the latter was responsible for major identification errors. The multiplex PCR method results were in complete agreement with the MLSA identifications but failed to distinguish the subspecies Streptococcus constellatus subsp. pharyngis and S. constellatus subsp. viborgensis. A total of 145 MLSA sequence types were present in our collection, indicating that within each taxon a number of different lineages are capable of causing infection. Significant antibiotic resistance was observed only to tetracycline, erythromycin, and clindamycin and was present in most taxa. MALDI-TOF MS is a reliable method for routine SAG species identification, while the need for identification to the subspecies level is not clearly established. Initially included in the viridans group streptococci, the species now recognized as the Streptococcus anginosus group (SAG) were first described as Streptococcus milleri in 1956 (1), but their taxonomic classification has remained in flux. Currently, the group includes three species, Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius (2-5) with unique genome signature regions (5). The species S. constellatus was subdivided into the subspecies S. constellatus subsp. pharyngis and S. constellatus subsp. constellatus (6). Recently, Jensen et al., based on multilocus sequence analysis (MLSA), divided S. anginosus into two subspecies-S. anginosus subsp. anginosus (the isolates formerly classified as S. anginosus) and S. anginosus subsp. whileyi-and they described the novel subspecies S. constellatus subsp. viborgensis (7).Most SAG strains share common features, such as small colony size, low growth rate, and a distinctive caramel smell (8, 9). However, SAG also present diversity in their other characteristics. These organisms may be nonhemolytic or display beta-or alphahemolysis when grown on blood agar plates (4, 5, 10), and they may present any of the A, C, F, or G Lancefield group antigens or lack Lancefield group antigen altogether (4,5,8,10). SAG, as with other members of the viridans group streptococci, are part of the human microbiota, colonizing the oral cavity, nasopharynx, and g...

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Section: Discussionsupporting

confidence: 72%

Comparing Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Phenotypic and Molecular Methods for Identification of Species within the Streptococcus anginosus Group

et al. 2015

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“…Historically, these organisms have been relatively susceptible to most antibiotics. However, the frequency of multidrug resistance has been increasing (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Much of the resistance and virulence associated with these organisms can be exchanged among multiple streptococcal species via horizontal transfer of genetic material (13,18,19).…”

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confidence: 99%

“…Much of the resistance and virulence associated with these organisms can be exchanged among multiple streptococcal species via horizontal transfer of genetic material (13,18,19). Antibiotic resistance has been reported primarily for penicillin, macrolides, and fluoroquinolones (4,6,7,9,12). The resistance related to the mef and erm genes, which confer resistance to macrolides, lincosamides, and streptogramin B, has been well characterized in VGS (3,4,7,12).…”

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confidence: 99%

“…Antibiotic resistance has been reported primarily for penicillin, macrolides, and fluoroquinolones (4,6,7,9,12). The resistance related to the mef and erm genes, which confer resistance to macrolides, lincosamides, and streptogramin B, has been well characterized in VGS (3,4,7,12). More recently, reports of daptomycin and linezolid resistance have also been published; these reports include both in vitro studies and in vivo studies with 2 clinical cases for each agent (20)(21)(22)(23)(24)(25).…”

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confidence: 99%

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Characterization of High-Level Daptomycin Resistance in Viridans Group Streptococci Developed upon In Vitro Exposure to Daptomycin

Akins

Katz

Monahan

et al. 2015

Antimicrob Agents Chemother

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cViridans group streptococci (VGS) are part of the normal flora that may cause bacteremia, often leading to endocarditis. We evaluated daptomycin against four clinical strains of VGS (MICs ‫؍‬ 1 or 2 g/ml) using an in vitro-simulated endocardial vegetation model, a simulated bacteremia model, and kill curves. Daptomycin exposure was simulated at 6 mg/kg of body weight and 8 mg/kg every 24 h for endocardial and bacteremia models. Total drug concentrations were used for analyses containing protein (albumin and pooled human serum), and free (unbound) drug concentrations (93% protein bound) were used for analyses not containing protein. Daptomycin MICs in the presence of protein were significantly higher than those in the absence of protein. Despite MICs below or at the susceptible breakpoint, all daptomycin regimens demonstrated limited kill in both pharmacodynamic models. A reduction of approximately 1 to 2 log 10 CFU was seen for all isolates and dosages except daptomycin at 6 mg/kg, which achieved a reduction of 2.7 log 10 CFU/g against one strain (Streptococcus gordonii 1649) in the endocardial model. Activity was similar in both pharmacodynamic models in the presence or absence of protein. Similar activity was noted in the kill curves over all multiples of the MIC. Regrowth by 24 h was seen even at 8؋ MIC. Postexposure daptomycin MICs for both pharmacodynamic models increased to >256 g/ml for all isolates by 24 and 72 h. Despite susceptibility to daptomycin by standard MIC methods, these VGS developed high-level daptomycin resistance (HLDR) after a short duration following drug exposure not attributed to modification or inactivation of daptomycin. Further evaluation is warranted to determine the mechanism of resistance and clinical implications.

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“…The predominance of the cMLS B phenotype in VGS isolated from blood has been reported from Korea (61.1%), France (77%), and Holland (73%) (3,9,22). However, in the United States, Canada, and Latin America (6,8), the M phenotype was the most common.…”

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confidence: 96%

In Vitro Activity of Telithromycin against Viridans Group Streptococci and Streptococcus bovis Isolated from Blood: Antimicrobial Susceptibility Patterns in Different Groups of Species

Rodríguez-Avial

Culebras

et al. 2005

Antimicrob Agents Chemother

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The in vitro activities of penicillin, erythromycin, clindamycin, and telithromycin were determined against 155 viridans group streptococci (VGS) and 18 Streptococcus bovis blood isolates. Heterogeneity in the susceptibility patterns and macrolide resistance phenotypes and genotypes in the different groups of VGS was detected. We found seven telithromycin-resistant S. bovis isolates all harboring the erm(B) gene.Viridans group streptococci (VGS) are the main commensals of the oropharyngeal cavity in humans. They are the leading cause of subacute bacterial endocarditis and have also emerged as important pathogens causing sepsis in neutropenic cancer patients. Streptococcus bovis is frequently found as part of the commensal bowel flora. These organisms are also agents of endocarditis. Bacteremia caused by S. bovis isolates is associated with malignancies of the gastrointestinal tract.Recent studies have shown that VGS are becoming increasingly resistant to many antibiotics, and it seems that antimicrobial resistance is not homogeneous among the different members of the group (1,7,8,20). Most studies of VGS report that Streptococcus mitis, in addition to being the most frequently isolated group, is also the group that shows the highest rates of penicillin resistance (1,7,8,10,17). However, reports about the susceptibility of other VGS and S. bovis are scarce. The aim of our study was to determine overall rates of VGS susceptibility to penicillin, macrolides, and telithromycin and also to determine whether there are any differences in the susceptibility patterns and erythromycin resistance mechanisms of the different species that make up this group.A total of 155 VGS and 18 S. bovis strains isolated from blood were collected between 1998 and 2003. Of the 173 isolates, 111 were isolated from 1998 to 2002 and were previously characterized in terms of their macrolide resistance (15). All strains were identified by standard methods (16) and by the Rapid ID32 Strep system (bioMérieux, Marcy l'Étoile, France) and then classified according to the review of Coykendall (4).Susceptibility to penicillin, erythromycin, clindamycin, and telithromycin was determined by the agar dilution method. MICs were interpreted using NCCLS criteria for Streptococcus other than Streptococcus pneumoniae. For telithromycin, since no NCCLS breakpoints have been established, we used those defined for S. pneumoniae (12). Macrolide resistance phenotypes were determined using a double-disk diffusion method (18). The presence of erm and mef genes was determined by PCR amplification with previously described primers specific for erm(A), erm(B), erm(C), and mef(A) (18,19). Of the 155 VGS, 72 isolates belonged to the S. mitis group; other groups included Streptococcus anginosus (49 isolates), Streptococcus sanguis (21 isolates), Streptococcus salivarius (11 isolates), and Streptococcus mutans (2 isolates).The in vitro activities of the antibiotics tested for the different streptococci, except for the two S. mutans group isolates, which were susceptible ...

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Antimicrobial susceptibility patterns and macrolide resistance genes of viridans group streptococci from blood cultures in Korea

Cited by 26 publications

References 7 publications

Comparing Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Phenotypic and Molecular Methods for Identification of Species within the Streptococcus anginosus Group

Comparing Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Phenotypic and Molecular Methods for Identification of Species within the Streptococcus anginosus Group

Characterization of High-Level Daptomycin Resistance in Viridans Group Streptococci Developed upon In Vitro Exposure to Daptomycin

In Vitro Activity of Telithromycin against Viridans Group Streptococci and Streptococcus bovis Isolated from Blood: Antimicrobial Susceptibility Patterns in Different Groups of Species

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