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Genome-Wide Transposon Mutagenesis Screens Identify Group A Streptococcus Genes Affecting Susceptibility to β-Lactam Antibiotics. J Bacteriol 2022; 204:e0028722. [PMID: 36374114 PMCID: PMC9765115 DOI: 10.1128/jb.00287-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Group A streptococcus (GAS) is a Gram-positive human bacterial pathogen responsible for more than 700 million infections annually worldwide. Beta-lactam antibiotics are the primary agents used to treat GAS infections. Naturally occurring GAS clinical isolates with decreased susceptibility to beta-lactam antibiotics attributed to mutations in PBP2X have recently been documented. This prompted us to perform a genome-wide screen to identify GAS genes that alter beta-lactam susceptibility in vitro. Using saturated transposon mutagenesis, we screened for GAS gene mutations conferring altered in vitro susceptibility to penicillin G and/or ceftriaxone, two beta-lactam antibiotics commonly used to treat GAS infections. In the aggregate, we found that inactivating mutations in 150 GAS genes are associated with altered susceptibility to penicillin G and/or ceftriaxone. Many of the genes identified were previously not known to alter beta-lactam susceptibility or affect cell wall biosynthesis. Using isogenic mutant strains, we confirmed that inactivation of clpX (Clp protease ATP-binding subunit) or cppA (CppA proteinase) resulted in decreased in vitro susceptibility to penicillin G and ceftriaxone. Deletion of murA1 (UDP-N-acetylglucosamine 1-carboxyvinyltransferase) conferred increased susceptibility to ceftriaxone. Our results provide new information about the GAS genes affecting susceptibility to beta-lactam antibiotics. IMPORTANCE Beta-lactam antibiotics are the primary drugs prescribed to treat infections caused by group A streptococcus (GAS), an important human pathogen. However, the molecular mechanisms of GAS interactions with beta-lactam antibiotics are not fully understood. In this study, we performed a genome-wide mutagenesis screen to identify GAS mutations conferring altered susceptibility to beta-lactam antibiotics. In the aggregate, we discovered that mutations in 150 GAS genes were associated with altered beta-lactam susceptibility. Many identified genes were previously not known to alter beta-lactam susceptibility or affect cell wall biosynthesis. Our results provide new information about the molecular mechanisms of GAS interaction with beta-lactam antibiotics.
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Chang JC, Wilkening RV, Rahbari KM, Federle MJ. Quorum Sensing Regulation of a Major Facilitator Superfamily Transporter Affects Multiple Streptococcal Virulence Factors. J Bacteriol 2022; 204:e0017622. [PMID: 35938850 PMCID: PMC9487453 DOI: 10.1128/jb.00176-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/19/2022] [Indexed: 01/04/2023] Open
Abstract
Cell-cell signaling mediated by Rgg-family transcription factors and their cognate pheromones is conserved in Firmicutes, including all streptococci. In Streptococcus pyogenes, or group A strep (GAS), one of these systems, the Rgg2/3 quorum sensing (QS) system, has been shown to regulate phenotypes, including cellular aggregation and biofilm formation, lysozyme resistance, and macrophage immunosuppression. Here, we show the abundance of several secreted virulence factors (streptolysin O, SpyCEP, and M protein) decreases upon induction of QS. The main mechanism underlying the changes in protein levels appears to be transcriptional, occurs downstream of the QS circuit, and is dysregulated by the deletion of an Rgg2/3 QS-regulated major facilitator superfamily (MFS) transporter. Additionally, we identify this MFS transporter as the factor responsible for a previously observed increase in aminoglycoside sensitivity in QS-induced cells. IMPORTANCE The production of virulence factors is a tightly regulated process in bacterial pathogens. Efforts to elucidate the mechanisms by which genes are regulated may advance the understanding of factors influencing pathogen behavior or cellular physiology. This work finds expression of a major facilitator superfamily (MFS) transporter, which is governed by a quorum sensing (QS) system, impacts the expression of multiple virulence factors and accounts for QS-dependent antibiotic susceptibility. Although the mechanism underlying this effect is not clear, MFS orthologs with high sequence similarity from S. pneumoniae and S. porcinus were unable to substitute indicating substrate specificity of the GAS MFS gene. These findings demonstrate novel associations between expression of a transmembrane transporter and virulence factor expression and aminoglycoside transport.
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Affiliation(s)
- Jennifer C. Chang
- Department of Pharmaceutical Sciences, University of Illinois Chicago, Chicago, Illinois, USA
| | - Reid V. Wilkening
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
| | - Kate M. Rahbari
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
| | - Michael J. Federle
- Department of Pharmaceutical Sciences, University of Illinois Chicago, Chicago, Illinois, USA
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
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Chiarot E, Pizza M. Animal models in vaccinology: state of the art and future perspectives for an animal-free approach. Curr Opin Microbiol 2021; 66:46-55. [PMID: 34953265 DOI: 10.1016/j.mib.2021.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 11/28/2022]
Abstract
Vaccine discovery and development is mainly driven by studies on immunogenicity and safety based on the appropriate animal models. In this review we will describe the importance of animal models in vaccinology, from research and development to pre-licensure and post-licensure commitments with particular emphasis on the advantages and limitations of each animal species. Finally, we will describe the most modern technologies, the new in vitro and ex vivo models and the new advances in the field which may drive into a new era of 'animal free' vaccinology.
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Opoku-Temeng C, Malachowa N, Kobayashi SD, DeLeo FR. Innate Host Defense against Klebsiella pneumoniae and the Outlook for Development of Immunotherapies. J Innate Immun 2021; 14:167-181. [PMID: 34628410 DOI: 10.1159/000518679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/14/2021] [Indexed: 11/19/2022] Open
Abstract
Klebsiella pneumoniae (K. pneumoniae) is a Gram-negative commensal bacterium and opportunistic pathogen. In healthy individuals, the innate immune system is adept at protecting against K. pneumoniae infection. Notably, the serum complement system and phagocytic leukocytes (e.g., neutrophils) are highly effective at eliminating K. pneumoniae and thereby preventing severe disease. On the other hand, the microbe is a major cause of healthcare-associated infections, especially in individuals with underlying susceptibility factors, such as pre-existing severe illness or immune suppression. The burden of K. pneumoniae infections in hospitals is compounded by antibiotic resistance. Treatment of these infections is often difficult largely because the microbes are usually resistant to multiple antibiotics (multidrug resistant [MDR]). There are a limited number of treatment options for these infections and new therapies, and preventative measures are needed. Here, we review host defense against K. pneumoniae and discuss recent therapeutic measures and vaccine approaches directed to treat and prevent severe disease caused by MDR K. pneumoniae.
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Affiliation(s)
- Clement Opoku-Temeng
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Natalia Malachowa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Scott D Kobayashi
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Frank R DeLeo
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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Fabri LV, Azzopardi KI, Osowicki J, Frost HR, Smeesters PR, Steer AC. An emm-type specific qPCR to track bacterial load during experimental human Streptococcus pyogenes pharyngitis. BMC Infect Dis 2021; 21:463. [PMID: 34020607 PMCID: PMC8138111 DOI: 10.1186/s12879-021-06173-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 05/12/2021] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Streptococcus pyogenes causes a profound global burden of morbidity and mortality across its diverse clinical spectrum. To support a new controlled human infection ('challenge') model seeking to accelerate S. pyogenes vaccine development, we aimed to develop an accurate and reliable molecular method for quantifying bacterial load from pharyngeal swabs collected during experimental human pharyngitis. METHODS Combined sequential RNA + DNA extraction from throat swabs was compared to traditional separate RNA-only and DNA-only extractions. An emm-type specific qPCR was developed to detect the emm75 challenge strain. Results from the qPCR were compared to culture, using throat swab samples collected in a human challenge study. RESULTS The qPCR was 100% specific for the emm75 challenge strain when tested against a panel of S. pyogenes emm-types and other respiratory pathogens. Combined RNA + DNA extraction had similar yield to traditional separate extractions. The combined extraction method and emm75 qPCR had 98.8% sensitivity compared to culture for throat swabs collected from challenge study participants. CONCLUSIONS We have developed a reliable molecular method for measuring S. pyogenes bacterial load from throat swabs collected in a controlled human infection model of S. pyogenes pharyngitis. TRIAL REGISTRATION NCT03361163 on 4th December 2017.
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Affiliation(s)
- Loraine V Fabri
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, Université Libre de Bruxelles, Brussels, Belgium
| | - Kristy I Azzopardi
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Joshua Osowicki
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.
- Infectious Diseases Unit, Department of General Medicine, The Royal Children's Hospital Melbourne, Melbourne, Victoria, Australia.
| | - Hannah R Frost
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Pierre R Smeesters
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, Université Libre de Bruxelles, Brussels, Belgium
- Academic Children Hospital Queen Fabiola, Université Libre de Bruxelles, Brussels, Belgium
- Molecular Bacteriology Laboratory, Université Libre de Bruxelles, Brussels, Belgium
| | - Andrew C Steer
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Infectious Diseases Unit, Department of General Medicine, The Royal Children's Hospital Melbourne, Melbourne, Victoria, Australia
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Weckel A, Guilbert T, Lambert C, Plainvert C, Goffinet F, Poyart C, Méhats C, Fouet A. Streptococcus pyogenes infects human endometrium by limiting the innate immune response. J Clin Invest 2021; 131:130746. [PMID: 33320843 DOI: 10.1172/jci130746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 12/10/2020] [Indexed: 11/17/2022] Open
Abstract
Group A Streptococcus (GAS), a Gram-positive human-specific pathogen, yields 517,000 deaths annually worldwide, including 163,000 due to invasive infections and among them puerperal fever. Before efficient prophylactic measures were introduced, the mortality rate for mothers during childbirth was approximately 10%; puerperal fever still accounts for over 75,000 maternal deaths annually. Yet, little is known regarding the factors and mechanisms of GAS invasion and establishment in postpartum infection. We characterized the early steps of infection in an ex vivo infection model of the human decidua, the puerperal fever portal of entry. Coordinate analysis of GAS behavior and the immune response led us to demonstrate that (a) GAS growth was stimulated by tissue products; (b) GAS invaded tissue and killed approximately 50% of host cells within 2 hours, and these processes required SpeB protease and streptolysin O (SLO) activities, respectively; and (c) GAS impaired the tissue immune response. Immune impairment occurred both at the RNA level, with only partial induction of the innate immune response, and protein level, in an SLO- and SpeB-dependent manner. Our study indicates that efficient GAS invasion of the decidua and the restricted host immune response favored its propensity to develop rapid invasive infections in a gynecological-obstetrical context.
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Affiliation(s)
- Antonin Weckel
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France.,Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France
| | - Thomas Guilbert
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France
| | - Clara Lambert
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France.,Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France
| | - Céline Plainvert
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France.,Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France.,Centre National de Référence des Streptocoques.,Hôpitaux Universitaires Paris Centre, Cochin, Assistance Publique Hôpitaux de Paris
| | - François Goffinet
- Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France.,Faculté de Médecine, Université Paris Descartes, and.,Service de Gynécologie Obstétrique I, Maternité Port Royal, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Claire Poyart
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France.,Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France.,Centre National de Référence des Streptocoques.,Hôpitaux Universitaires Paris Centre, Cochin, Assistance Publique Hôpitaux de Paris
| | - Céline Méhats
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France.,Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France
| | - Agnès Fouet
- Université de Paris, Institut Cochin, INSERM, U1016, CNRS, UMR8104, Paris, France.,Département Hospitalo-Universitaire Risk & Pregnancy, Port Royal Maternity, Paris, France.,Centre National de Référence des Streptocoques
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