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Wu X, Alibayov B, Xiang X, Lattar SM, Sakai F, Medders AA, Antezana B, Keller L, Vidal AGJ, Tzeng YL, Robinson DA, Stephens D, Yu Y, Vidal JE. Ultrastructural, metabolic and genetic determinants of the acquisition of macrolide resistance by Streptococcus pneumoniae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.27.573471. [PMID: 38234816 PMCID: PMC10793443 DOI: 10.1101/2023.12.27.573471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Aim Streptococcus pneumoniae (Spn) acquires genes for macrolide resistance, MEGA or ermB, in the human host. These genes are carried either in the chromosome, or on integrative conjugative elements (ICEs). Here, we investigated molecular determinants of the acquisition of macrolide resistance. Methods and Results Whole genome analysis was conducted for 128 macrolide-resistant pneumococcal isolates to identify the presence of MEGA (44.5%, 57/128) or ermB (100%), and recombination events in Tn916-related elements or in the locus comCDE encoding competence genes. Confocal and electron microscopy studies demonstrated that, during the acquisition of macrolide resistance, pneumococcal strains formed clusters of varying size, with the largest aggregates having a median size of ~1600 μm2. Remarkably, these pneumococcal aggregates comprise both encapsulated and nonencapsulated pneumococci, exhibited physical interaction, and spanned extracellular and intracellular compartments. We assessed the recombination frequency (rF) for the acquisition of macrolide resistance by a recipient D39 strain, from pneumococcal strains carrying MEGA (~5.4 kb) in the chromone, or in large ICEs (>23 kb). Notably, the rF for the acquisition of MEGA, whether in the chromosome or carried on an ICE was similar. However, the rF adjusted to the acquisition of the full-length ICE (~52 kb), compared to that of the capsule locus (~23 kb) that is acquired by transformation, was three orders of magnitude higher. Finally, metabolomics studies revealed a link between the acquisition of ICE and the metabolic pathways involving nicotinic acid and sucrose. Conclusions Extracellular and intracellular pneumococcal clusters facilitate the acquisition of full-length ICE at a rF higher than that of typical transformation events, involving distinct metabolic changes that present potential targets for interventions.
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Affiliation(s)
- Xueqing Wu
- Department of Infectious Diseases, Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310052, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou 310052, China
| | - Babek Alibayov
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS 39056, United States
| | - Xi Xiang
- Department of Clinical Laboratory, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua 321000, China
| | - Santiago M. Lattar
- Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta GA 30322, United States
| | - Fuminori Sakai
- Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta GA 30322, United States
| | - Austin A. Medders
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS 39056, United States
| | - Brenda Antezana
- Department of Medicine, School of Medicine, Emory University, Atlanta GA 30322, United States
| | - Lance Keller
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS 39056, United States
| | - Ana G. J. Vidal
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS 39056, United States
| | - Yih-Ling Tzeng
- Department of Medicine, School of Medicine, Emory University, Atlanta GA 30322, United States
| | - D. Ashley Robinson
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS 39056, United States
| | - David Stephens
- Department of Medicine, School of Medicine, Emory University, Atlanta GA 30322, United States
| | - Yunsong Yu
- Department of Infectious Diseases, Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310052, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou 310052, China
| | - Jorge E. Vidal
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson MS 39056, United States
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Antezana BS, Lohsen S, Wu X, Vidal JE, Tzeng YL, Stephens DS. Dissemination of Tn 916-Related Integrative and Conjugative Elements in Streptococcus pneumoniae Occurs by Transformation and Homologous Recombination in Nasopharyngeal Biofilms. Microbiol Spectr 2023; 11:e0375922. [PMID: 36912669 PMCID: PMC10101023 DOI: 10.1128/spectrum.03759-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 02/02/2023] [Indexed: 03/14/2023] Open
Abstract
Multidrug resistance in Streptococcus pneumoniae (or pneumococcus) continues to be a global challenge. An important class of antibiotic resistance determinants disseminating in S. pneumoniae are >20-kb Tn916-related integrative and conjugative elements (ICEs), such as Tn2009, Tn6002, and Tn2010. Although conjugation has been implicated as the transfer mechanism for ICEs in several bacteria, including S. pneumoniae, the molecular basis for widespread dissemination of pneumococcal Tn916-related ICEs remains to be fully elucidated. We found that Tn2009 acquisition was not detectable via in vitro transformation nor conjugative mating with donor GA16833, yielding a transfer frequency of <10-7. GA16833 Tn2009 conjugative gene expression was not significantly induced, and ICE circular intermediate formation was not detected in biofilms. Consistently, Tn2009 transfer efficiency in biofilms was not affected by deletion of the ICE conjugative gene ftsK. However, GA16833 Tn2009 transfer occurred efficiently at a recombination frequency (rF) of 10-4 in dual-strain biofilms formed in a human nasopharyngeal cell bioreactor. DNase I addition and deletions of the early competence gene comE or transformation apparatus genes comEA and comEC in the D39 recipient strain prevented Tn2009 acquisition (rF of <10-7). Genome sequencing and single nucleotide polymorphism analyses of independent recombinants of recipient genotype identified ~33- to ~55-kb donor DNAs containing intact Tn2009, supporting homologous recombination. Additional pneumococcal donor and recipient combinations were demonstrated to efficiently transfer Tn916-related ICEs at a rF of 10-4 in the biofilms. Tn916-related ICEs horizontally disseminate at high frequency in human nasopharyngeal S. pneumoniae biofilms by transformation and homologous recombination of >30-kb DNA fragments into the pneumococcal genome. IMPORTANCE The World Health Organization has designated Streptococcus pneumoniae as a priority pathogen for research and development of new drug treatments due to extensive multidrug resistance. Multiple strains of S. pneumoniae colonize and form mixed biofilms in the human nasopharynx, which could enable exchange of antibiotic resistance determinants. Tn916-related integrative and conjugative elements (ICEs) are largely responsible for the widespread presence of macrolide and tetracycline resistance in S. pneumoniae. Utilizing a system that simulates colonization of donor and recipient S. pneumoniae strains in the human nasopharynx, efficient transfer of Tn916-related ICEs occurred in human nasopharyngeal biofilms, in contrast to in vitro conditions of planktonic cells with exogenous DNA. This high-frequency Tn916-related ICE transfer between S. pneumoniae strains in biofilms was due to transformation and homologous recombination, not conjugation. Understanding the molecular mechanism for dissemination of Tn916-related ICEs can facilitate the design of new strategies to combat antibiotic resistance.
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Affiliation(s)
- Brenda S. Antezana
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Emory University Laney Graduate School, Atlanta, Georgia, USA
| | - Sarah Lohsen
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Xueqing Wu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University College of Medicine, Hangzhou, China
| | - Jorge E. Vidal
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Yih-Ling Tzeng
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - David S. Stephens
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
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