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Doğan E, Sydow K, Heiden SE, Eger E, Wassilew G, Proctor RA, Bohnert JA, Idelevich EA, Schaufler K, Becker K. Klebsiella pneumoniae exhibiting a phenotypic hyper-splitting phenomenon including the formation of small colony variants. Front Cell Infect Microbiol 2024; 14:1372704. [PMID: 38601740 PMCID: PMC11004228 DOI: 10.3389/fcimb.2024.1372704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/07/2024] [Indexed: 04/12/2024] Open
Abstract
In this study, we characterized a Klebsiella pneumoniae strain in a patient with shrapnel hip injury, which resulted in multiple phenotypic changes, including the formation of a small colony variant (SCV) phenotype. Although already described since the 1960s, there is little knowledge about SCV phenotypes in Enterobacteriaceae. The formation of SCVs has been recognized as a bacterial strategy to evade host immune responses and compromise the efficacy of antimicrobial therapies, leading to persistent and recurrent courses of infections. In this case, 14 isolates with different resisto- and morpho-types were distinguished from the patient's urine and tissue samples. Whole genome sequencing revealed that all isolates were clonally identical belonging to the K. pneumoniae high-risk sequence type 147. Subculturing the SCV colonies consistently resulted in the reappearance of the initial SCV phenotype and three stable normal-sized phenotypes with distinct morphological characteristics. Additionally, an increase in resistance was observed over time in isolates that shared the same colony appearance. Our findings highlight the complexity of bacterial behavior by revealing a case of phenotypic "hyper-splitting" in a K. pneumoniae SCV and its potential clinical significance.
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Affiliation(s)
- Eyüp Doğan
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Katharina Sydow
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
| | - Stefan E. Heiden
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
| | - Elias Eger
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
| | - Georgi Wassilew
- Center for Orthopedics, Trauma Surgery and Rehabilitation Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Richard A. Proctor
- Departments of Medical Microbiology/Immunology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Jürgen A. Bohnert
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Evgeny A. Idelevich
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Katharina Schaufler
- Department of Epidemiology and Ecology of Antimicrobial Resistance, Helmholtz Institute for One Health, Helmholtz Centre for Infection Research Helmholtz Center for Infection Research (HZI), Greifswald, Germany
- University Medicine Greifswald, Greifswald, Germany
| | - Karsten Becker
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
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Mayer K, Kucklick M, Marbach H, Ehling-Schulz M, Engelmann S, Grunert T. Within-Host Adaptation of Staphylococcus aureus in a Bovine Mastitis Infection Is Associated with Increased Cytotoxicity. Int J Mol Sci 2021; 22:8840. [PMID: 34445550 DOI: 10.3390/ijms22168840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/04/2021] [Accepted: 08/10/2021] [Indexed: 11/17/2022] Open
Abstract
Within-host adaptation is a typical feature of chronic, persistent Staphylococcus aureus infections. Research projects addressing adaptive changes due to bacterial in-host evolution increase our understanding of the pathogen’s strategies to survive and persist for a long time in various hosts such as human and bovine. In this study, we investigated the adaptive processes of S. aureus during chronic, persistent bovine mastitis using a previously isolated isogenic strain pair from a dairy cow with chronic, subclinical mastitis, in which the last variant (host-adapted, Sigma factor SigB-deficient) quickly replaced the initial, dominant variant. The strain pair was cultivated under specific in vitro infection-relevant growth-limiting conditions (iron-depleted RPMI under oxygen limitation). We used a combinatory approach of surfaceomics, molecular spectroscopic fingerprinting and in vitro phenotypic assays. Cellular cytotoxicity assays using red blood cells and bovine mammary epithelial cells (MAC-T) revealed changes towards a more cytotoxic phenotype in the host-adapted isolate with an increased alpha-hemolysin (α-toxin) secretion, suggesting an improved capacity to penetrate and disseminate the udder tissue. Our results foster the hypothesis that within-host evolved SigB-deficiency favours extracellular persistence in S. aureus infections. Here, we provide new insights into one possible adaptive strategy employed by S. aureus during chronic, bovine mastitis, and we emphasise the need to analyse genotype–phenotype associations under different infection-relevant growth conditions.
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