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Yaeger LN, Ranieri MRM, Chee J, Karabelas-Pittman S, Rudolph M, Giovannoni AM, Harvey H, Burrows LL. A genetic screen identifies a role for oprF in Pseudomonas aeruginosa biofilm stimulation by subinhibitory antibiotics. NPJ Biofilms Microbiomes 2024; 10:30. [PMID: 38521769 PMCID: PMC10960818 DOI: 10.1038/s41522-024-00496-7] [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: 09/06/2023] [Accepted: 03/05/2024] [Indexed: 03/25/2024] Open
Abstract
Biofilms are surface-associated communities of bacteria that grow in a self-produced matrix of polysaccharides, proteins, and extracellular DNA (eDNA). Sub-minimal inhibitory concentrations (sub-MIC) of antibiotics induce biofilm formation, potentially as a defensive response to antibiotic stress. However, the mechanisms behind sub-MIC antibiotic-induced biofilm formation are unclear. We show that treatment of Pseudomonas aeruginosa with multiple classes of sub-MIC antibiotics with distinct targets induces biofilm formation. Further, addition of exogenous eDNA or cell lysate failed to increase biofilm formation to the same extent as antibiotics, suggesting that the release of cellular contents by antibiotic-driven bacteriolysis is insufficient. Using a genetic screen for stimulation-deficient mutants, we identified the outer membrane porin OprF and the ECF sigma factor SigX as important. Similarly, loss of OmpA - the Escherichia coli OprF homolog - prevented sub-MIC antibiotic stimulation of E. coli biofilms. Our screen also identified the periplasmic disulfide bond-forming enzyme DsbA and a predicted cyclic-di-GMP phosphodiesterase encoded by PA2200 as essential for biofilm stimulation. The phosphodiesterase activity of PA2200 is likely controlled by a disulfide bond in its regulatory domain, and folding of OprF is influenced by disulfide bond formation, connecting the mutant phenotypes. Addition of reducing agent dithiothreitol prevented sub-MIC antibiotic biofilm stimulation. Finally, activation of a c-di-GMP-responsive promoter follows treatment with sub-MIC antibiotics in the wild-type but not an oprF mutant. Together, these results show that antibiotic-induced biofilm formation is likely driven by a signaling pathway that translates changes in periplasmic redox state into elevated biofilm formation through increases in c-di-GMP.
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Affiliation(s)
- Luke N Yaeger
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Michael R M Ranieri
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Jessica Chee
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Sawyer Karabelas-Pittman
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Madeleine Rudolph
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Alessio M Giovannoni
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Hanjeong Harvey
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Lori L Burrows
- Biochemistry and Biomedical Sciences and the Michael G. DeGroote Centre for Infectious Disease Research, McMaster University, Hamilton, ON, Canada.
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Ching C, Brychcy M, Nguyen B, Muller P, Pearson AR, Downs M, Regan S, Isley B, Fowle W, Chai Y, Godoy VG. RecA levels modulate biofilm development in Acinetobacter baumannii. Mol Microbiol 2024; 121:196-212. [PMID: 37918886 DOI: 10.1111/mmi.15188] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 10/06/2023] [Accepted: 10/17/2023] [Indexed: 11/04/2023]
Abstract
Infections caused by Acinetobacter baumannii, a Gram-negative opportunistic pathogen, are difficult to eradicate due to the bacterium's propensity to quickly gain antibiotic resistances and form biofilms, a protective bacterial multicellular community. The A. baumannii DNA damage response (DDR) mediates the antibiotic resistance acquisition and regulates RecA in an atypical fashion; both RecALow and RecAHigh cell types are formed in response to DNA damage. The findings of this study demonstrate that the levels of RecA can influence formation and dispersal of biofilms. RecA loss results in surface attachment and prominent biofilms, while elevated RecA leads to diminished attachment and dispersal. These findings suggest that the challenge to treat A. baumannii infections may be explained by the induction of the DDR, common during infection, as well as the delicate balance between maintaining biofilms in low RecA cells and promoting mutagenesis and dispersal in high RecA cells. This study underscores the importance of understanding the fundamental biology of bacteria to develop more effective treatments for infections.
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Affiliation(s)
- Carly Ching
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Merlin Brychcy
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Brian Nguyen
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Paul Muller
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | | | - Margaret Downs
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Samuel Regan
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Breanna Isley
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - William Fowle
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Yunrong Chai
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Veronica G Godoy
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
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Pharmacokinetic and Pharmacodynamic Optimization of Antibiotic Therapy in Cystic Fibrosis Patients: Current Evidences, Gaps in Knowledge and Future Directions. Clin Pharmacokinet 2021; 60:409-445. [PMID: 33486720 DOI: 10.1007/s40262-020-00981-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2020] [Indexed: 10/22/2022]
Abstract
Antibiotic therapy is one of the main treatments for cystic fibrosis (CF). It aims to eradicate bacteria during early infection, calms down the inflammatory process, and leads to symptom resolution of pulmonary exacerbations. CF can modify both the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of antibiotics, therefore specific PK/PD endpoints should be determined in the context of CF. Currently available data suggest that optimal PK/PD targets cannot be attained in sputum with intravenous aminoglycosides. Continuous infusion appears preferable for β-lactam antibiotics, but optimal concentrations in sputum are unlikely to be reached, with some possible exceptions such as meropenem and ceftolozane. Usual doses are likely suboptimal for fluoroquinolones and linezolid, whereas daily doses of 45-60 mg/kg and 200 mg could be convenient for vancomycin and doxycycline, respectively. Weekly azithromycin doses of 22-30 mg/kg could also be appropriate for its anti-inflammatory effect. The difficulty with achieving optimal concentrations supports the use of combined treatments and the inhaled administration route, as very high local concentrations, concomitantly with low systemic exposure, can be obtained with the inhaled route for aminoglycosides, colistin, and fluoroquinolones, thus minimizing the risk of toxicity.
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Ciofu O, Tolker-Nielsen T, Jensen PØ, Wang H, Høiby N. Antimicrobial resistance, respiratory tract infections and role of biofilms in lung infections in cystic fibrosis patients. Adv Drug Deliv Rev 2015; 85:7-23. [PMID: 25477303 DOI: 10.1016/j.addr.2014.11.017] [Citation(s) in RCA: 206] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 11/11/2014] [Accepted: 11/23/2014] [Indexed: 02/08/2023]
Abstract
Lung infection is the main cause of morbidity and mortality in patients with cystic fibrosis and is mainly dominated by Pseudomonas aeruginosa. The biofilm mode of growth makes eradication of the infection impossible, and it causes a chronic inflammation in the airways. The general mechanisms of biofilm formation and antimicrobial tolerance and resistance are reviewed. Potential anti-biofilm therapeutic targets such as weakening of biofilms by quorum-sensing inhibitors or antibiotic killing guided by pharmacokinetics and pharmacodynamics of antibiotics are presented. The vicious circle of adaptive evolution of the persisting bacteria imposes important therapeutic challenges and requires development of new drug delivery systems able to reach the different niches occupied by the bacteria in the lung of cystic fibrosis patients.
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Involvement of stress-related genes polB and PA14_46880 in biofilm formation of Pseudomonas aeruginosa. Infect Immun 2014; 82:4746-57. [PMID: 25156741 DOI: 10.1128/iai.01915-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Chronic infections of Pseudomonas aeruginosa are generally established through production of biofilm. During biofilm formation, production of an extracellular matrix and establishment of a distinct bacterial phenotype make these infections difficult to eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behind P. aeruginosa biofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genes polB and PA14_46880 reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the ΔpolB and ΔPA14_46880 strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression of algR, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation of polB and PA14_46880 may inhibit transition of P. aeruginosa from a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding of P. aeruginosa biofilm formation and chronic biofilm infections.
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Ciofu O, Mandsberg LF, Wang H, Høiby N. Phenotypes selected during chronic lung infection in cystic fibrosis patients: implications for the treatment ofPseudomonas aeruginosabiofilm infections. ACTA ACUST UNITED AC 2012; 65:215-25. [DOI: 10.1111/j.1574-695x.2012.00983.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 04/23/2012] [Accepted: 04/24/2012] [Indexed: 12/18/2022]
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Gotoh H, Kasaraneni N, Devineni N, Dallo SF, Weitao T. SOS involvement in stress-inducible biofilm formation. BIOFOULING 2010; 26:603-611. [PMID: 20603726 DOI: 10.1080/08927014.2010.501895] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Bacterial biofilm formation can be induced by antimicrobial and DNA damage agents. These agents trigger the SOS response, in which SOS sensor RecA stimulates auto-cleavage of repressor LexA. These observations lead to a hypothesis of a connection between stress-inducible biofilm formation and the RecA-LexA interplay. To test this hypothesis, three biofilm assays were conducted, viz. the standard 96-well assay, confocal laser scanning microscopy, and the newly developed biofilm-on-paper assay. It was found that biofilm stimulation by the DNA replication inhibitor hydroxyurea was dependent on RecA and appeared repressed by the non-cleavable LexA of Pseudomonas aeruginosa. Surprisingly, deletion of lexA led to reduction of both normal and stress-inducible biofilm formation, suggesting that the wild-type LexA contributes to biofilm formation. The decreases was not the result of poor growth of the mutants. These results suggest SOS involvement in hydroxyurea-inducible biofilm formation. In addition, with the paper biofilm assay, it was found that degradation of the biofilm matrix DNA by DNase I appeared to render the biofilms susceptible to the replication inhibitor. The puzzling questions concerning the roles of LexA in DNA release in the biofilm context are discussed.
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Affiliation(s)
- H Gotoh
- Department of Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA
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Gotoh H, Zhang Y, Dallo SF, Hong S, Kasaraneni N, Weitao T. Pseudomonas aeruginosa, under DNA replication inhibition, tends to form biofilms via Arr. Res Microbiol 2008; 159:294-302. [PMID: 18434096 DOI: 10.1016/j.resmic.2008.02.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Revised: 01/10/2008] [Accepted: 02/01/2008] [Indexed: 11/29/2022]
Abstract
Bacteria infecting eukaryotic hosts often encounter therapeutic antimicrobial and DNA damaging agents and respond by forming biofilms. While mechanisms of biofilm response are incompletely understood, they seem to involve bacterial second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) signaling. We hypothesized that DNA replication inhibition induces bacterial biofilm formation via c-di-GMP signaling. Evidently, we found that Pseudomonas aeruginosa mounted a biofilm response to the subinhibitory DNA replication inhibitors hydroxyurea and nalidixic acid, but planktonic proliferation was inhibited. The biofilm response was suppressed either genetically by mutations causing planktonic resistance or biochemically by reversal of replication inhibition. Biofilms were induced by a mechanism of stimulated adhesion of planktonic filaments having impaired DNA replication, as examined under fluorescence microscopy. Induction was suppressed by either inhibition or mutation of Arr-a c-di-GMP phosphodiesterase. These results suggest that P. aeruginosa, under DNA replication stress, tends to form biofilms via Arr. The profound implications of the SOS response, planktonic-sessile and bacteria-cancer relationships are discussed.
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Affiliation(s)
- Hideo Gotoh
- Department of Biology, The University of Texas at San Antonio, 6900 North Loop 1604 West, San Antonio, TX 78249, USA.
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Kaneko Y, Thoendel M, Olakanmi O, Britigan BE, Singh PK. The transition metal gallium disrupts Pseudomonas aeruginosa iron metabolism and has antimicrobial and antibiofilm activity. J Clin Invest 2007; 117:877-88. [PMID: 17364024 PMCID: PMC1810576 DOI: 10.1172/jci30783] [Citation(s) in RCA: 419] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2006] [Accepted: 01/23/2007] [Indexed: 11/17/2022] Open
Abstract
A novel antiinfective approach is to exploit stresses already imposed on invading organisms by the in vivo environment. Fe metabolism is a key vulnerability of infecting bacteria because organisms require Fe for growth, and it is critical in the pathogenesis of infections. Furthermore, humans have evolved potent Fe-withholding mechanisms that can block acute infection, prevent biofilm formation leading to chronic infection, and starve bacteria that succeed in infecting the host. Here we investigate a "Trojan horse" strategy that uses the transition metal gallium to disrupt bacterial Fe metabolism and exploit the Fe stress of in vivo environments. Due to its chemical similarity to Fe, Ga can substitute for Fe in many biologic systems and inhibit Fe-dependent processes. We found that Ga inhibits Pseudomonas aeruginosa growth and biofilm formation and kills planktonic and biofilm bacteria in vitro. Ga works in part by decreasing bacterial Fe uptake and by interfering with Fe signaling by the transcriptional regulator pvdS. We also show that Ga is effective in 2 murine lung infection models. These data, along with the fact that Ga is FDA approved (for i.v. administration) and there is the dearth of new antibiotics in development, make Ga a potentially promising new therapeutic for P. aeruginosa infections.
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Affiliation(s)
- Yukihiro Kaneko
- Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
Cincinnati VA Medical Center, Cincinnati, Ohio, USA
| | - Matthew Thoendel
- Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
Cincinnati VA Medical Center, Cincinnati, Ohio, USA
| | - Oyebode Olakanmi
- Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
Cincinnati VA Medical Center, Cincinnati, Ohio, USA
| | - Bradley E. Britigan
- Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
Cincinnati VA Medical Center, Cincinnati, Ohio, USA
| | - Pradeep K. Singh
- Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, Washington, USA.
Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
Cincinnati VA Medical Center, Cincinnati, Ohio, USA
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Bagge N, Schuster M, Hentzer M, Ciofu O, Givskov M, Greenberg EP, Høiby N. Pseudomonas aeruginosa biofilms exposed to imipenem exhibit changes in global gene expression and beta-lactamase and alginate production. Antimicrob Agents Chemother 2004; 48:1175-87. [PMID: 15047518 PMCID: PMC375275 DOI: 10.1128/aac.48.4.1175-1187.2004] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lungs of cystic fibrosis (CF) patients are commonly colonized with Pseudomonas aeruginosa biofilms. Chronic endobronchial P. aeruginosa infections are impossible to eradicate with antibiotics, but intensive suppressive antibiotic therapy is essential to maintain the lung function of CF patients. The treatment often includes beta-lactam antibiotics. How these antibiotics influence gene expression in the surviving biofilm population of P. aeruginosa is not clear. Thus, we used the microarray technology to study the effects of subinhibitory concentrations of a beta-lactam antibiotic, imipenem, on gene expression in biofilm populations. Many genes showed small but statistically significant differential expression in response to imipenem. We identified 34 genes that were induced or repressed in biofilms exposed to imipenem more than fivefold compared to the levels of induction or repression for the controls. As expected, the most strongly induced gene was ampC, which codes for chromosomal beta-lactamase. We also found that genes coding for alginate biosynthesis were induced by exposure to imipenem. Alginate production is correlated to the development of impaired lung function, and P. aeruginosa strains isolated from chronically colonized lungs of CF patients are nearly always mucoid due to the overproduction of alginate. Exposure to subinhibitory concentrations of imipenem caused structural changes in the biofilm, e.g., an increased biofilm volume. Increased levels of alginate production may be an unintended adverse consequence of imipenem treatment in CF patients.
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Affiliation(s)
- Niels Bagge
- Department of Clinical Microbiology, Rigshospitalet, and Department of Bacteriology, Institute for Medical Microbiology and Immunology, Panum Institute, University of Copenhagen, Denmark.
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