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Darby EM, Moran RA, Holden E, Morris T, Harrison F, Clough B, McInnes RS, Schneider L, Frickel EM, Webber MA, Blair JMA. Differential development of antibiotic resistance and virulence between Acinetobacter species. mSphere 2024:e0010924. [PMID: 38578105 DOI: 10.1128/msphere.00109-24] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 03/13/2024] [Indexed: 04/06/2024] Open
Abstract
The two species that account for most cases of Acinetobacter-associated bacteremia in the United Kingdom are Acinetobacter lwoffii, often a commensal but also an emerging pathogen, and Acinetobacter baumannii, a well-known antibiotic-resistant species. While these species both cause similar types of human infection and occupy the same niche, A. lwoffii (unlike A. baumannii) has thus far remained susceptible to antibiotics. Comparatively little is known about the biology of A. lwoffii, and this is the largest study on it conducted to date, providing valuable insights into its behaviour and potential threat to human health. This study aimed to explain the antibiotic susceptibility, virulence, and fundamental biological differences between these two species. The relative susceptibility of A. lwoffii was explained as it encoded fewer antibiotic resistance and efflux pump genes than A. baumannii (9 and 30, respectively). While both species had markers of horizontal gene transfer, A. lwoffii encoded more DNA defense systems and harbored a far more restricted range of plasmids. Furthermore, A. lwoffii displayed a reduced ability to select for antibiotic resistance mutations, form biofilm, and infect both in vivo and in in vitro models of infection. This study suggests that the emerging pathogen A. lwoffii has remained susceptible to antibiotics because mechanisms exist to make it highly selective about the DNA it acquires, and we hypothesize that the fact that it only harbors a single RND system restricts the ability to select for resistance mutations. This provides valuable insights into how development of resistance can be constrained in Gram-negative bacteria. IMPORTANCE Acinetobacter lwoffii is often a harmless commensal but is also an emerging pathogen and is the most common cause of Acinetobacter-derived bloodstream infections in England and Wales. In contrast to the well-studied and often highly drug-resistant A. baumannii, A. lwoffii has remained susceptible to antibiotics. This study explains why this organism has not evolved resistance to antibiotics. These new insights are important to understand why and how some species develop antibiotic resistance, while others do not, and could inform future novel treatment strategies.
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Affiliation(s)
- Elizabeth M Darby
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Robert A Moran
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Emma Holden
- Quadram Institute Bioscience, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Theresa Morris
- Centre for Electron Microscopy, University of Birmingham, Birmingham, United Kingdom
| | - Freya Harrison
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Barbara Clough
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ross S McInnes
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ludwig Schneider
- Centre for Electron Microscopy, University of Birmingham, Birmingham, United Kingdom
| | - Eva M Frickel
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Mark A Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, Norfolk, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Jessica M A Blair
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
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Troth TD, McInnes RS, Dunn SJ, Mirza J, Whittaker AH, Goodchild SA, Loman NJ, Harding SV, van Schaik W. Differences in the gut microbiota between Gurkhas and soldiers of British origin. PLoS One 2023; 18:e0292645. [PMID: 38113233 PMCID: PMC10729956 DOI: 10.1371/journal.pone.0292645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/26/2023] [Indexed: 12/21/2023] Open
Abstract
Previous work indicated that the incidence of travellers' diarrhoea (TD) is higher in soldiers of British origin, when compared to soldiers of Nepalese descent (Gurkhas). We hypothesise that the composition of the gut microbiota may be a contributing factor in the risk of developing TD in soldiers of British origin. This study aimed to characterise the gut microbial composition of Gurkha and non-Gurkha soldiers of the British Army. Recruitment of 38 soldiers (n = 22 Gurkhas, n = 16 non-Gurkhas) and subsequent stool collection, enabled shotgun metagenomic sequencing-based analysis of the gut microbiota. The microbiota of Gurkhas had significantly (P < 0.05) lower diversity, for both Shannon and Simpson diversity indices, using species level markers than the gut microbiota of non-Gurkha soldiers. Non-metric Multidimensional Scaling (NMDS) of the Bray-Curtis distance matrix revealed a significant difference in the composition of the gut microbiota between Gurkhas and non-Gurkha soldiers, at both the species level (P = 0.0178) and the genus level (P = 0.0483). We found three genera and eight species that were significantly enriched in the non-Gurkha group and one genus (Haemophilus) and one species (Haemophilus parainfluenzae) which were enriched in the Gurkha group. The difference in the microbiota composition between Gurkha soldiers and soldiers of British origin may contribute to higher colonization resistance against diarrhoeal pathogens in the former group. Our findings may enable further studies into interventions that modulate the gut microbiota of soldiers to prevent TD during deployment.
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Affiliation(s)
- Thomas D. Troth
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ross S. McInnes
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Steven J. Dunn
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Jeremy Mirza
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Annalise H. Whittaker
- CBR Division, Defence and Science Technology Laboratory, Salisbury, Wiltshire, United Kingdom
| | - Sarah A. Goodchild
- CBR Division, Defence and Science Technology Laboratory, Salisbury, Wiltshire, United Kingdom
| | - Nicholas J. Loman
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Sarah V. Harding
- CBR Division, Defence and Science Technology Laboratory, Salisbury, Wiltshire, United Kingdom
- School of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Willem van Schaik
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
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McInnes RS, McCallum GE, Lamberte LE, van Schaik W. Horizontal transfer of antibiotic resistance genes in the human gut microbiome. Curr Opin Microbiol 2020; 53:35-43. [PMID: 32143027 DOI: 10.1016/j.mib.2020.02.002] [Citation(s) in RCA: 137] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/28/2020] [Accepted: 02/02/2020] [Indexed: 01/05/2023]
Abstract
Infections caused by antibiotic-resistant bacteria are a major threat to public health. The pathogens causing these infections can acquire antibiotic resistance genes in a process termed horizontal gene transfer (HGT). HGT is a common event in the human gut microbiome, that is, the microbial ecosystem of the human intestinal tract. HGT in the gut microbiome can occur via different mechanisms of which transduction and conjugation have been best characterised. Novel bioinformatic tools and experimental approaches have been developed to determine the association of antibiotic resistance genes with their microbial hosts and to quantify the extent of HGT in the gut microbiome. Insights from studies into HGT in the gut microbiome may lead to the development of novel interventions to minimise the spread of antibiotic resistance genes among commensals and opportunistic pathogens.
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Affiliation(s)
- Ross S McInnes
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Gregory E McCallum
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Lisa E Lamberte
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
| | - Willem van Schaik
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
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