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Characterization of in vitro-generated and clinical optochin-resistant strains of Streptococcus pneumoniae isolated from Argentina.

ABSTRACT: Optochin susceptibility is a key test used for pneumococcal diagnosis, but optochin-resistant (Opt(r)) pneumococci have been reported in the last 2 decades. In this work, we characterized eight Opt(r) clinical strains which presented a new mutation, G47V, a predominant A49S mutation (recently reported in Brazil) and A49T. These mutations were found in the c subunit of the F(0)F(1) ATPase encoded by the atpC gene, and W206C was found in the a subunit encoded by the atpA gene. The Opt(r) clinical isolates were analyzed by BOX PCR, multilocus sequence typing, and serotype and antimicrobial resistance profiles, and they showed no epidemiological relationship. To characterize the Opt(r) mutations that could emerge among clinical strains, we studied a pool of spontaneous Opt(r) colonies obtained in vitro from the virulent D39 strain. We compared the atpAC mutations of these Opt(r) pneumococci (with or without passage through C57BL/6 mice) with those described in the clinical isolates. This analysis revealed three new mutations, G47V and L26M in the c subunit and L184S in the a subunit. Most of the mutations identified in the laboratory-generated Opt(r) strains were also found in clinical strains, with the exception of the L26M and L184S mutations, and we suppose that both mutations could emerge among invasive strains in the future. Considering that atpAC are essential genes, we propose that all spontaneous mutations that confer in vitro optochin resistance would not present severe physiological alterations in S. pneumoniae and may be carried by circulating pneumococcal strains.

SUBMITTER: Cortes PR

PROVIDER: S-EPMC2446823 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

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Characterization of in vitro-generated and clinical optochin-resistant strains of Streptococcus pneumoniae isolated from Argentina.

Cortes Paulo R PR Orio Andrea G Albarracín AG Regueira Mabel M Piñas Germán E GE Echenique José J

Journal of clinical microbiology 20080416 6

Optochin susceptibility is a key test used for pneumococcal diagnosis, but optochin-resistant (Opt(r)) pneumococci have been reported in the last 2 decades. In this work, we characterized eight Opt(r) clinical strains which presented a new mutation, G47V, a predominant A49S mutation (recently reported in Brazil) and A49T. These mutations were found in the c subunit of the F(0)F(1) ATPase encoded by the atpC gene, and W206C was found in the a subunit encoded by the atpA gene. The Opt(r) clinical ...[more]

PMID: 18417665

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Project description:Bovine herpesvirus 4 (BoHV-4) is increasingly considered as responsible for various problems of the reproductive tract. The virus infects mainly blood mononuclear cells and displays specific tropism for vascular endothelia, reproductive and fetal tissues. Epidemiological studies suggest its impact on reproductive performance, and its presence in various sites in the reproductive tract highlights its potential transmission in transfer-stage embryos. This work describes the biological and genetic characterization of BoHV-4 strains isolated from an in vitro bovine embryo production system. BoHV-4 strains were isolated in 2011 and 2013 from granulosa cells and bovine oocytes from ovary batches collected at a local abattoir, used as "starting material" for in vitro production of bovine embryos. Compatible BoHV-4-CPE was observed in the co-culture of granulosa cells and oocytes with MDBK cells. The identity of the isolates was confirmed by PCR assays targeting three ORFs of the viral genome. The phylogenetic analyses of the strains suggest that they were evolutionary unlinked. Therefore it is possible that BoHV-4 ovary infections occurred regularly along the evolution of the virus, at least in Argentina, which can have implications in the systems of in vitro embryo production. Thus, although BoHV-4 does not appear to be a frequent risk factor for in vitro embryo production, data are still limited. This study reveals the potential of BoHV-4 transmission via embryo transfer. Moreover, the high variability among the BoHV-4 strains isolated from aborted cows in Argentina highlights the importance of further research on the role of this virus as an agent with the potential to cause reproductive disease in cattle. The genetic characterization of the isolated strains provides data to better understand the pathogenesis of BoHV-4 infections. Furthermore, it will lead to fundamental insights into the molecular aspects of the virus and the means by which these strains circulate in the herds.

Project description:INTRODUCTION:Pakistan has one of the highest burdens of pneumococcal diseases in the world, but unfortunately studies in this demanding research area are limited in the region. Pneumococcal surface protein A (PspA) is the next generation pneumococcal vaccine candidate as the protein locates on the Streptococcus pneumoniae surface. Its gene, pspA, might be encoded by all pneumococci, and the protein has proven immunogenicity. The molecular characterization of PspA, pneumococcal serotype distribution and antibiotic susceptibility are important for regional diversity studies. METHODS:In this study, we examined 38 pneumococcal isolates from pneumococcal diseased (pneumonia/meningitis) patients blood or cerebrospinal fluid. There were no specific inclusion or exclusion criteria, but all the individuals [ages 1 month to 12 years (male/female)] had undergone no antibiotic treatment in at least the past 3 months and had no vaccination history. We investigated the serotype distribution, antibiotic susceptibility, prevalence of the PspA family and its active domain's fusion, expression and antigenicity. RESULTS:Our finding shows that serotype 19F is the most prevalent (23.6%) followed by 18B (15.78%) (non-vaccine type) in all isolated pneumococcal strains. All strains were susceptible to chloramphenicol and linezolid, while 80% were resistant to gentamycin. Genotyping revealed that ~ 80% (N = 31/38) of pneumococcal strains produce PspA belonging to family 2 and clade 3. We further selected three active domains of PspA (family 2 and clade 3) by in silico analysis, merged together into a fusion gene for expression study, and its antigenicity was analyzed by Western blotting. CONCLUSION:Serotypes 19F and 18B (non-vaccine type) are the most prevalent in the Pakistani pneumococcal isolates. The PspA family 2 proteins produced by Pakistani pneumococcal isolates have high sequence homologies with each other and differ from those produced by strains isolated in the rest of the world. The PspA fusion peptide had a proven antigenic response in western blotting, with no considerable correlation among pneumococcal serotypes, antibiotic susceptibility and PspA family/clade distribution.

Dataset Information

Characterization of in vitro-generated and clinical optochin-resistant strains of Streptococcus pneumoniae isolated from Argentina.

Publications

Characterization of in vitro-generated and clinical optochin-resistant strains of Streptococcus pneumoniae isolated from Argentina.

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