1
|
Cao L, Yang H, Huang Z, Lu C, Chen F, Zhang J, Ye P, Yan J, Zhang H. Direct prediction of antimicrobial resistance in Pseudomonas aeruginosa by metagenomic next-generation sequencing. Front Microbiol 2024; 15:1413434. [PMID: 38903781 PMCID: PMC11187003 DOI: 10.3389/fmicb.2024.1413434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Accepted: 05/27/2024] [Indexed: 06/22/2024] Open
Abstract
Objective Pseudomonas aeruginosa has strong drug resistance and can tolerate a variety of antibiotics, which is a major problem in the management of antibiotic-resistant infections. Direct prediction of multi-drug resistance (MDR) resistance phenotypes of P. aeruginosa isolates and clinical samples by genotype is helpful for timely antibiotic treatment. Methods In the study, whole genome sequencing (WGS) data of 494 P. aeruginosa isolates were used to screen key anti-microbial resistance (AMR)-associated genes related to imipenem (IPM), meropenem (MEM), piperacillin/tazobactam (TZP), and levofloxacin (LVFX) resistance in P. aeruginosa by comparing genes with copy number differences between resistance and sensitive strains. Subsequently, for the direct prediction of the resistance of P. aeruginosa to four antibiotics by the AMR-associated features screened, we collected 74 P. aeruginosa positive sputum samples to sequence by metagenomics next-generation sequencing (mNGS), of which 1 sample with low quality was eliminated. Then, we constructed the resistance prediction model. Results We identified 93, 88, 80, 140 AMR-associated features for IPM, MEM, TZP, and LVFX resistance in P. aeruginosa. The relative abundance of AMR-associated genes was obtained by matching mNGS and WGS data. The top 20 features with importance degree for IPM, MEM, TZP, and LVFX resistance were used to model, respectively. Then, we used the random forest algorithm to construct resistance prediction models of P. aeruginosa, in which the areas under the curves of the IPM, MEM, TZP, and LVFX resistance prediction models were all greater than 0.8, suggesting these resistance prediction models had good performance. Conclusion In summary, mNGS can predict the resistance of P. aeruginosa by directly detecting AMR-associated genes, which provides a reference for rapid clinical detection of drug resistance of pathogenic bacteria.
Collapse
Affiliation(s)
- Lichao Cao
- Shenzhen Nucleus Gene Technology Co., Ltd., Shenzhen, Guangdong Province, China
| | - Huilin Yang
- Department of Laboratory Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong Province, China
| | - Zhigang Huang
- Department of Laboratory Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong Province, China
| | - Chang Lu
- Department of Laboratory Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong Province, China
| | - Fang Chen
- Shenzhen Nucleus Gene Technology Co., Ltd., Shenzhen, Guangdong Province, China
| | - Jiahao Zhang
- Shenzhen Nucleus Gene Technology Co., Ltd., Shenzhen, Guangdong Province, China
| | - Peng Ye
- Department of Laboratory Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong Province, China
| | - Jinjin Yan
- Department of Laboratory Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong Province, China
| | - Hezi Zhang
- Shenzhen Nucleus Gene Technology Co., Ltd., Shenzhen, Guangdong Province, China
| |
Collapse
|
2
|
Otun SO, Graca R, Achilonu I. Combating Aminoglycoside Resistance: From Structural and Functional Characterisation to Therapeutic Challenges with RKAAT. Curr Protein Pept Sci 2024; 25:454-468. [PMID: 38314602 DOI: 10.2174/0113892037278814231226104509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/04/2023] [Accepted: 12/07/2023] [Indexed: 02/06/2024]
Abstract
A comprehensive knowledge of aminoglycoside-modifying enzymes (AMEs) and their role in bacterial resistance mechanisms is urgently required due to the rising incidence of antibiotic resistance, particularly in Klebsiella pneumoniae infections. This study explores the essential features of AMEs, including their structural and functional properties, the processes by which they contribute to antibiotic resistance, and the therapeutic importance of aminoglycosides. The study primarily examines the Recombinant Klebsiella pneumoniae Aminoglycoside Adenylyl Transferase (RKAAT), particularly emphasizing its biophysical characteristics and the sorts of resistance it imparts. Furthermore, this study examines the challenges presented by RKAAT-mediated resistance, an evaluation of treatment methods and constraints, and options for controlling infection. The analysis provides a prospective outlook on strategies to address and reduce antibiotic resistance. This extensive investigation seeks to provide vital insights into the continuing fight against bacterial resistance, directing future research efforts and medicinal approaches.
Collapse
Affiliation(s)
- Sarah Oluwatobi Otun
- Department of Molecular and Cell Biology, Protein Structure-function Unit, University of Witwatersrand, Johannesburg, South Africa
| | - Richard Graca
- Department of Molecular and Cell Biology, Protein Structure-function Unit, University of Witwatersrand, Johannesburg, South Africa
| | - Ikechukwu Achilonu
- Department of Molecular and Cell Biology, Protein Structure-function Unit, University of Witwatersrand, Johannesburg, South Africa
| |
Collapse
|
3
|
Erdmann MB, Gardner PP, Lamont IL. The PitA protein contributes to colistin susceptibility in Pseudomonas aeruginosa. PLoS One 2023; 18:e0292818. [PMID: 37824582 PMCID: PMC10569645 DOI: 10.1371/journal.pone.0292818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 09/28/2023] [Indexed: 10/14/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes a wide range of problematic infections in individuals with predisposing conditions. Infections can be treated with colistin but some isolates are resistant to this antibiotic. To better understand the genetic basis of resistance, we experimentally evolved 19 independent resistant mutants from the susceptible laboratory strain PAO1. Whole genome sequencing identified mutations in multiple genes including phoQ and pmrB that have previously been associated with resistance, pitA that encodes a phosphate transporter, and carB and eno that encode enzymes of metabolism. Individual mutations were engineered into the genome of strain PAO1. Mutations in pitA, pmrB and phoQ increased the minimum inhibitory concentration (MIC) for colistin 8-fold, making the bacteria resistant. Engineered pitA/phoQ and pitA/pmrB double mutants had higher MICs than single mutants, demonstrating additive effects on colistin susceptibility. Single carB and eno mutations did not increase the MIC suggesting that their effect is dependent on the presence of other mutations. Many of the resistant mutants had increased susceptibility to β-lactams and lower growth rates than the parental strain demonstrating that colistin resistance can impose a fitness cost. Two hundred and fourteen P. aeruginosa isolates from a range of sources were tested and 18 (7.8%) were colistin resistant. Sequence variants in genes identified by experimental evolution were present in the 18 resistant isolates and may contribute to resistance. Overall our results identify pitA mutations as novel contributors to colistin resistance and demonstrate that resistance can reduce fitness of the bacteria.
Collapse
Affiliation(s)
| | - Paul P. Gardner
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Iain L. Lamont
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| |
Collapse
|
4
|
Thacharodi A, Hassan S, Singh T, Mandal R, Chinnadurai J, Khan HA, Hussain MA, Brindhadevi K, Pugazhendhi A. Bioremediation of polycyclic aromatic hydrocarbons: An updated microbiological review. CHEMOSPHERE 2023; 328:138498. [PMID: 36996919 DOI: 10.1016/j.chemosphere.2023.138498] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/08/2023] [Accepted: 03/21/2023] [Indexed: 06/19/2023]
Abstract
A class of organic priority pollutants known as PAHs is of critical public health and environmental concern due to its carcinogenic properties as well as its genotoxic, mutagenic, and cytotoxic properties. Research to eliminate PAHs from the environment has increased significantly due to awareness about their negative effects on the environment and human health. Various environmental factors, including nutrients, microorganisms present and their abundance, and the nature and chemical properties of the PAH affect the biodegradation of PAHs. A large spectrum of bacteria, fungi, and algae have ability to degrade PAHs with the biodegradation capacity of bacteria and fungi receiving the most attention. A considerable amount of research has been conducted in the last few decades on analyzing microbial communities for their genomic organization, enzymatic and biochemical properties capable of degrading PAH. While it is true that PAH degrading microorganisms offer potential for recovering damaged ecosystems in a cost-efficient way, new advances are needed to make these microbes more robust and successful at eliminating toxic chemicals. By optimizing some factors like adsorption, bioavailability and mass transfer of PAHs, microorganisms in their natural habitat could be greatly improved to biodegrade PAHs. This review aims to comprehensively discuss the latest findings and address the current wealth of knowledge in the microbial bioremediation of PAHs. Additionally, recent breakthroughs in PAH degradation are discussed in order to facilitate a broader understanding of the bioremediation of PAHs in the environment.
Collapse
Affiliation(s)
- Aswin Thacharodi
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Saqib Hassan
- Division of Non-Communicable Diseases, Indian Council of Medical Research (ICMR), New Delhi, 110029, India; Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry, 605014, India
| | - Tripti Singh
- Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, 201309, India
| | - Ramkrishna Mandal
- Department of Chemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Jeganathan Chinnadurai
- Department of Research and Development, Dr. Thacharodi's Laboratories, No. 24, 5th Cross, Thanthaiperiyar Nagar, Ellapillaichavadi, Puducherry, 605005, India
| | - Hilal Ahmad Khan
- Department of Chemistry, Pondicherry University, Puducherry, 605014, India
| | - Mir Ashiq Hussain
- Department of Chemistry, Pondicherry University, Puducherry, 605014, India
| | - Kathirvel Brindhadevi
- Center for Transdisciplinary Research (CFTR), Department of Pharmacology, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, India
| | - Arivalagan Pugazhendhi
- School of Engineering, Lebanese American University, Byblos, Lebanon; University Centre for Research & Development, Department of Civil Engineering, Chandigarh University, Mohali,140103, India.
| |
Collapse
|
5
|
Atassi G, Medernach R, Scheetz M, Nozick S, Rhodes NJ, Murphy-Belcaster M, Murphy KR, Alisoltani A, Ozer EA, Hauser AR. Genomics of Aminoglycoside Resistance in Pseudomonas aeruginosa Bloodstream Infections at a United States Academic Hospital. Microbiol Spectr 2023; 11:e0508722. [PMID: 37191517 PMCID: PMC10269721 DOI: 10.1128/spectrum.05087-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 04/22/2023] [Indexed: 05/17/2023] Open
Abstract
Pseudomonas aeruginosa frequently becomes resistant to aminoglycosides by the acquisition of aminoglycoside modifying enzyme (AME) genes and the occurrence of mutations in the mexZ, fusA1, parRS, and armZ genes. We examined resistance to aminoglycosides in a collection of 227 P. aeruginosa bloodstream isolates collected over 2 decades from a single United States academic medical institution. Resistance rates of tobramycin and amikacin were relatively stable over this time, while the resistance rates of gentamicin were somewhat more variable. For comparison, we examined resistance rates to piperacillin-tazobactam, cefepime, meropenem, ciprofloxacin, and colistin. Resistance rates to the first four antibiotics were also stable, although uniformly higher for ciprofloxacin. Colistin resistance rates were initially quite low, rose substantially, and then began to decrease at the end of the study. Clinically relevant AME genes were identified in 14% of isolates, and mutations predicted to cause resistance were relatively common in the mexZ and armZ genes. In a regression analysis, resistance to gentamicin was associated with the presence of at least one gentamicin-active AME gene and significant mutations in mexZ, parS, and fusA1. Resistance to tobramycin was associated with the presence of at least one tobramycin-active AME gene. An extensively drug-resistant strain, PS1871, was examined further and found to contain five AME genes, most of which were within clusters of antibiotic resistance genes embedded in transposable elements. These findings demonstrate the relative contributions of aminoglycoside resistance determinants to P. aeruginosa susceptibilities at a United States medical center. IMPORTANCE Pseudomonas aeruginosa is frequently resistant to multiple antibiotics, including aminoglycosides. The rates of resistance to aminoglycosides in bloodstream isolates collected over 2 decades at a United States hospital remained constant, suggesting that antibiotic stewardship programs may be effective in countering an increase in resistance. Mutations in the mexZ, fusA1, parR, pasS, and armZ genes were more common than acquisition of genes encoding aminoglycoside modifying enzymes. The whole-genome sequence of an extensively drug resistant isolate indicates that resistance mechanisms can accumulate in a single strain. Together, these results suggest that aminoglycoside resistance in P. aeruginosa remains problematic and confirm known resistance mechanisms that can be targeted for the development of novel therapeutics.
Collapse
Affiliation(s)
- Giancarlo Atassi
- Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rachel Medernach
- Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Marc Scheetz
- Department of Pharmacy Practice, Pharmacometrics Center of Excellence, Chicago College of Pharmacy, Midwestern University, Downers Grove, Illinois, USA
| | - Sophia Nozick
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nathaniel J. Rhodes
- Pharmacometrics Center of Excellence, College of Graduate Studies, Department of Pharmacology, Midwestern University, Downers Grove, Illinois, USA
| | - Megan Murphy-Belcaster
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Katherine R. Murphy
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Arghavan Alisoltani
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Egon A. Ozer
- Department of Medicine (Division of Infectious Diseases), Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Alan R. Hauser
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Department of Medicine (Division of Infectious Diseases), Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| |
Collapse
|
6
|
Thacharodi A, Hassan S, Hegde TA, Thacharodi DD, Brindhadevi K, Pugazhendhi A. Water a major source of endocrine-disrupting chemicals: An overview on the occurrence, implications on human health and bioremediation strategies. ENVIRONMENTAL RESEARCH 2023; 231:116097. [PMID: 37182827 DOI: 10.1016/j.envres.2023.116097] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/24/2023] [Accepted: 05/09/2023] [Indexed: 05/16/2023]
Abstract
Endocrine disrupting chemicals (EDCs) are toxic compounds that occur naturally or are the output of anthropogenic activities that negatively impact both humans and wildlife. A number of diseases are associated with these disruptors, including reproductive disorders, cardiovascular disorders, kidney disease, neurological disorders, autoimmune disorders, and cancer. Due to their integral role in pharmaceuticals and cosmetics, packaging companies, agro-industries, pesticides, and plasticizers, the scientific awareness on natural and artificial EDCs are increasing. As these xenobiotic compounds tend to bioaccumulate in body tissues and may also persist longer in the environment, the concentrations of these organic compounds may increase far from their original point of concentrations. Water remains as the major sources of how humans and animals are exposed to EDCs. However, these toxic compounds cannot be completely biodegraded nor bioremediated from the aqueous medium with conventional treatment strategies thereby requiring much more efficient strategies to combat EDC contamination. Recently, genetically engineered microorganism, genome editing, and the knowledge of protein and metabolic engineering has revolutionized the field of bioremediation thereby helping to breakdown EDCs effectively. This review shed lights on understanding the importance of aquatic mediums as a source of EDCs exposure. Furthermore, the review sheds light on the consequences of these EDCs on human health as well as highlights the importance of different remediation and bioremediation approaches. Particular attention is paid to the recent trends and perspectives in order to attain sustainable approaches to the bioremediation of EDCs. Additionally, rigorous restrictions to preclude the discharge of estrogenic chemicals into the environment should be followed in efforts to combat EDC pollution.
Collapse
Affiliation(s)
- Aswin Thacharodi
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand; Thacharodi's Laboratories, Department of Research and Development, Puducherry, 605005, India
| | - Saqib Hassan
- Future Leaders Mentoring Fellow, American Society for Microbiology, Washington, 20036, USA; Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry, 605014, India
| | - Thanushree A Hegde
- Civil Engineering Department, NMAM Institute of Technology, Nitte, Karnataka, 574110, India
| | - Dhanya Dilip Thacharodi
- Thacharodi's Laboratories, Department of Research and Development, Puducherry, 605005, India
| | - Kathirvel Brindhadevi
- Emerging Materials for Energy and Environmental Applications Research Group, School of Engineering and Technology, Van Lang University, Ho Chi Minh City, Viet Nam
| | - Arivalagan Pugazhendhi
- Emerging Materials for Energy and Environmental Applications Research Group, School of Engineering and Technology, Van Lang University, Ho Chi Minh City, Viet Nam.
| |
Collapse
|
7
|
Papa-Ezdra R, Cordeiro NF, Outeda M, Garcia-Fulgueiras V, Araújo L, Seija V, Ayala JA, Bado I, Vignoli R. Novel Resistance Regions Carrying Tn aphA6, blaVIM-2, and blaPER-1, Embedded in an IS Pa40-Derived Transposon from Two Multi-Resistant Pseudomonas aeruginosa Clinical Isolates. Antibiotics (Basel) 2023; 12:antibiotics12020304. [PMID: 36830215 PMCID: PMC9952335 DOI: 10.3390/antibiotics12020304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/27/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
Antibiotic resistance is an alarming problem throughout the world and carbapenem-resistant Pseudomonas aeruginosa has been cataloged as critical in the World Health Organization list of microorganisms in urgent need for the development of new antimicrobials. In this work, we describe two novel resistance regions responsible for conferring a multidrug resistance phenotype to two clinical isolates of P. aeruginosa (Pa873 and Pa6415) obtained from patients hospitalized in the ICU of University Hospital of Uruguay. Bacterial identification and antibiotic susceptibility tests were performed using MALDI-TOF and the Vitek 2 system, respectively. WGS was performed for both isolates using Oxford Nanopore Technologies and Illumina and processed by means of hybrid assembly. Both isolates were resistant to ceftazidime, cefepime, piperacillin-tazobactam, aztreonam, and imipenem. Strain Pa6415 also showed resistance to ciprofloxacin. Both strains displayed MICs below the susceptibility breakpoint for CAZ-AVI plus 4 mg/L of aztreonam as well as cefiderocol. Both resistance regions are flanked by the left and right inverted repeats of ISPa40 in two small regions spanning 39.3 and 35.6 kb, for Pa6415 and Pa873, respectively. The resistance region of Pa6415 includes TnaphA6, and the new Tn7516 consists of IRi, In899, qacEΔ1-sul1-ISCR1, qnrVC6-ISCR1-blaPER-1-qacEΔ1-sul1, araJ-like, IS481-like tnpA, ISPa17, and IRR. On the other hand, the resistance region of Pa873 includes Tnaph6 and the new Tn7517 (IRi, In899, qacEΔ1-sul1, ISCR1-blaPER-1-qacEΔ1-sul1, araJ-like, IS481-like tnpA, ISPa17, and IRR). It is necessary to monitor the emergence of genetic structures that threaten to invalidate the available therapeutic resources.
Collapse
Affiliation(s)
- Romina Papa-Ezdra
- Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Av. Alfredo Navarro 3051, Montevideo 11600, Uruguay
| | - Nicolás F. Cordeiro
- Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Av. Alfredo Navarro 3051, Montevideo 11600, Uruguay
| | - Matilde Outeda
- Departamento de Laboratorio Clínico, Área Microbiología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Av. Italia s/n, Montevideo 11600, Uruguay
| | - Virginia Garcia-Fulgueiras
- Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Av. Alfredo Navarro 3051, Montevideo 11600, Uruguay
| | - Lucía Araújo
- Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Av. Alfredo Navarro 3051, Montevideo 11600, Uruguay
| | - Verónica Seija
- Departamento de Laboratorio Clínico, Área Microbiología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Av. Italia s/n, Montevideo 11600, Uruguay
| | - Juan A. Ayala
- Centro de Biología Molecular “Severo Ochoa” (CBMSO)-CSIC, C. Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Inés Bado
- Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Av. Alfredo Navarro 3051, Montevideo 11600, Uruguay
- Correspondence: (I.B.); (R.V.)
| | - Rafael Vignoli
- Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Av. Alfredo Navarro 3051, Montevideo 11600, Uruguay
- Correspondence: (I.B.); (R.V.)
| |
Collapse
|
8
|
Gene-Gene Interactions Reduce Aminoglycoside Susceptibility of Pseudomonas aeruginosa through Efflux Pump-Dependent and -Independent Mechanisms. Antibiotics (Basel) 2023; 12:antibiotics12010152. [PMID: 36671353 PMCID: PMC9854422 DOI: 10.3390/antibiotics12010152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/10/2023] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
Pseudomonas aeruginosa causes a wide range of acute and chronic infections. Aminoglycosides are a cornerstone of treatment, but isolates are often resistant. The purpose of this research was to better understand the genetic basis of aminoglycoside resistance in P. aeruginosa. Bioinformatic approaches identified mutations in resistance-associated genes in the clinical isolates of P. aeruginosa. The common mutations were then engineered into the genome of P. aeruginosa reference strain PAO1. Mutations in the elongation factor gene fusA1 caused the biggest reduction in aminoglycoside susceptibility, with mutations in the two-component regulator gene amgS and the efflux pump regulator gene mexZ having less impact. This susceptibility was further reduced by combinations of mutations. Mutations in fusA1, amgS and mexZ all increased the expression of the mexXY efflux pump that is strongly associated with aminoglycoside resistance. Furthermore, the fusA1 amgS mexZ triple mutant had the highest efflux pump gene expression. Engineering fusA1 and amgS mutants lacking this efflux pump showed that fusA1 and amgS also reduce aminoglycoside susceptibility through additional mechanisms. The fusA1 and amgS mutations reduced bacterial growth, showing that these mutations have a fitness cost. Our findings demonstrate the complex interplay between mutations, efflux pump expression and other mechanisms for reducing the susceptibility of P. aeruginosa to aminoglycosides.
Collapse
|