Dataset Information

New genetic context of lnu(B) composed of two multi-resistance gene clusters in clinical Streptococcus agalactiae ST-19 strains.

ABSTRACT: Background:Clindamycin is a lincosamide antibiotic used to treat staphylococcal and streptococcal infections. Reports of clinical Streptococcus agalactiae isolates with the rare lincosamide resistance/macrolide susceptibility (LR/MS) phenotype are increasing worldwide. In this study, we characterised three clinical S. agalactiae strains with the unusual L phenotype from China. Methods:Three clinical S. agalactiae strains, Sag3, Sag27 and Sag4104, with the L phenotype were identified from 186 isolates collected from 2016 to 2018 in Shanghai, China. The MICs of clindamycin, erythromycin, tetracycline, levofloxacin, and penicillin were determined using Etest. PCR for the lnu(B) gene was conducted. Whole genome sequencing and sequence analysis were carried out to investigate the genetic context of lnu(B). Efforts to transfer lincomycin resistance by conjugation and to identify the circular form by inverse PCR were made. Results:Sag3, Sag27, and Sag4104 were susceptible to erythromycin (MIC ?0.25?mg/L) but resistant to clindamycin (MIC ?1?mg/L). lnu(B) was found to be responsible for the L phenotype. lnu(B) in Sag3 and Sag27 were chromosomally located in an aadE-spw-lsa(E)-lnu(B) resistance gene cluster adjacent to an upstream 7-kb tet(L)-cat resistance gene cluster. Two resistance gene clusters were flanked by the IS6-like element, IS1216. Sag4104 only contained partial genes of aadE-spw-lsa(E)-lnu(B) resistance gene cluster and was also flanked by IS1216. Conclusion:These results established the presence of the L phenotype associated with lnu(B) in clinical S. agalactiae isolates in China. The lnu(B)-containing multi-resistance gene cluster possibly acts as a composite transposon flanked by IS1216 and as a vehicle for the dissemination of multidrug resistance among S. agalactiae.

SUBMITTER: Zhou K

PROVIDER: S-EPMC6632187 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

New genetic context of <i>lnu(B)</i> composed of two multi-resistance gene clusters in clinical <i>Streptococcus agalactiae</i> ST-19 strains.

Zhou Kaixin K Zhu Dongan D Tao Ying Y Xie Lianyan L Han Lizhong L Zhang Yibo Y Sun Jingyong J

Antimicrobial resistance and infection control 20190715

<h4>Background</h4>Clindamycin is a lincosamide antibiotic used to treat staphylococcal and streptococcal infections. Reports of clinical <i>Streptococcus agalactiae</i> isolates with the rare lincosamide resistance/macrolide susceptibility (L<sup>R</sup>/M<sup>S</sup>) phenotype are increasing worldwide. In this study, we characterised three clinical <i>S. agalactiae</i> strains with the unusual L phenotype from China.<h4>Methods</h4>Three clinical <i>S. agalactiae</i> strains, Sag3, Sag27 and ...[more]

PMID: 31346458

Similar Datasets

Project description:The widely spread Streptococcus agalactiae (also known as Group B Streptococcus, GBS) "hypervirulent" ST17 clone is strongly associated with neonatal meningitis. The PI-2b locus is mainly found in ST17 strains but is also present in a few non ST17 human isolates such as the ST-7 prototype strain A909. Here, we analysed the expression of the PI-2b pilus in the ST17 strain BM110 as compared to the non ST17 A909. Comparative genome analyses revealed the presence of a 43-base pair (bp) hairpin-like structure in the upstream region of PI-2b operon in all 26 ST17 genomes, which was absent in the 8 non-ST17 strains carrying the PI-2b locus. Deletion of this 43-bp sequence in strain BM110 resulted in a 3- to 5-fold increased transcription of PI-2b. Characterization of PI-2b promoter region in A909 and BM110 strains was carried out by RNAseq, primer extension, qRT-PCR and transcriptional fusions with gfp as reporter gene. Our results indicate the presence of a single promoter (Ppi2b) with a transcriptional start site (TSS) mapped 37 bases upstream of the start codon of the first PI-2b gene. The large operon of 16 genes located upstream of PI-2b codes for the group B carbohydrate (also known as antigen B), a major constituent of the bacterial cell wall. We showed that the hairpin sequence located between antigen B and PI-2b operons is a transcriptional terminator. In A909, increased expression of PI-2b probably results from read-through transcription from antigen B operon. In addition, we showed that an extended 5' promoter region is required for maximal transcription of gfp as a reporter gene in S. agalactiae from Ppi2b promoter. Gene reporter assays performed in Lactococcus lactis strain NZ9000, a related non-pathogenic Gram-positive species, revealed that GBS-specific regulatory factors are required to drive PI-2b transcription. PI-2b expression is up-regulated in the BM110?covR mutant as compared to the parental BM110 strain, but this effect is probably indirect. Collectively, our results indicate that PI-2b expression is regulated in GBS ST17 strains, which may confer a selective advantage in the human host either by reducing host immune responses and/or increasing their dissemination potential.

Project description:BACKGROUND:MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression at the post-transcriptional level and play a key role in the control of innate and adaptive immune responses. For a subclinical infection such as bovine streptococcal mastitis, early detection is a great challenge, and miRNA profiling could potentially assist in the diagnosis and contribute to the understanding of the pathogenicity and defense mechanisms. We have examined the miRNA repertoire and the transcript level of six key immune genes [tumor necrosis factor alpha (TNF?), interleukin-1 beta (IL-1?), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10) and transforming growth factor beta 1 (TGF?1)] during the early phase response of bovine immature macrophages to in vitro infection with live Streptococcus agalactiae. Next generation sequencing of small RNA libraries from 20 cultures of blood monocyte-derived macrophages exposed to either one of two sequence types of S. agalactiae (ST103 or ST12) for 6 h in vitro and unchallenged controls was performed. RESULTS:Analyzes of over 356 million high quality sequence reads, revealed differential expression of 17 and 44 miRNAs (P?<?0.05) in macrophages infected with ST103 and ST12, respectively, versus unchallenged control cultures. We also identified the expression of 31 potentially novel bovine miRNAs. Pathway analysis of the differentially regulated miRNAs and their predicted target genes in the macrophages infected with ST12 revealed significant enrichment for inflammatory response and apoptosis, while significant enrichment for integrin and GABA signaling were found in ST103 infected macrophages. Furthermore, both bacterial strains regulated miRNAs involved in the alternative activation of macrophages. The transcript levels of TNF-?, IL-1?, IL-6, IL-8 and IL-10 were significantly up-regulated by both bacterial strains, however the expression of TGF?1 was significantly down-regulated only by ST12. CONCLUSIONS:Our study identified pathogen-induced differential regulation of miRNAs controlling inflammation and polarization in bovine macrophages. This implies that miRNAs have potential to serve as biomarkers for early detection of bacterial infection.

Project description:Streptococcus agalactiae (Group B Streptococcus; GBS) is a major contributor to obstetric and neonatal bacterial sepsis. Serotype III strains cause the majority of late-onset sepsis and meningitis in babies, and thus appear to have an enhanced invasive capacity compared with the other serotypes that cause disease predominantly in immunocompromised pregnant women. We compared the serotype III and V whole genome sequences, strains NEM316 and 2603VR respectively, in an attempt to identify genetic attributes of strain NEM316 that might explain the propensity of strain NEM316 to cause late-onset disease in babies. Fourteen putative pathogenicity islands were described in the strain NEM316 whole genome sequence. Using PCR- and targeted microarray- strategies, the presence of these islands were assessed in a diverse strain collection including 18 colonizing isolates from healthy pregnant women, and 13 and 8 invasive isolates from infants with early- and late-onset sepsis, respectively.Side-by-side comparison of the strain NEM316 and strain 2603VR genomes revealed that they are extremely similar, with the only major difference being the capsulation loci and mobile genetic elements. PCR and Comparative Genome Hybridization (CGH) were used to define the presence of each island in 39 GBS isolates. Only islands I, VI, XII, and possibly X, met criteria of a true pathogenicity island, but no significant correlation was found between the presence of any of the fourteen islands and whether the strains were invasive or colonizing. Possible associations were seen between the presence of island VI and late-onset sepsis, and island X and early-onset sepsis, which warrant further investigation.The NEM316 and 2603VR strains are remarkable in that their whole genome sequences are so similar, suggesting that the capsulation loci or other genetic differences, such as pathogenicity islands, are the main determinants of the propensity of serotype III strains to cause late-onset disease. This study supports the notion that GBS strain NEM316 has four putative pathogenicity islands, but none is absolutely necessary for disease causation, whether early- or late-onset sepsis. Mobile genetic elements are a common feature of GBS isolates, with each strain having its own peculiar burden of transposons, phages, integrases and integrated plasmids. The majority of these are unlikely to influence the disease capacity of an isolate. Serotype associated disease phenotypes may thus be solely related to differences in the capsulation loci.

Dataset Information

New genetic context of lnu(B) composed of two multi-resistance gene clusters in clinical Streptococcus agalactiae ST-19 strains.

Publications

New genetic context of <i>lnu(B)</i> composed of two multi-resistance gene clusters in clinical <i>Streptococcus agalactiae</i> ST-19 strains.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets