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Article ; Online: Methods to monitor bacterial growth and replicative rates at the single-cell level.

Marro, Florian C / Laurent, Frédéric / Josse, Jérôme / Blocker, Ariel J

2022 Volume 46, Issue 6

Abstract: The heterogeneity of bacterial growth and replicative rates within a population was proposed a century ago notably to explain the presence of bacterial persisters. The term "growth rate" at the single-cell level corresponds to the increase in size or ... ...

Abstract	The heterogeneity of bacterial growth and replicative rates within a population was proposed a century ago notably to explain the presence of bacterial persisters. The term "growth rate" at the single-cell level corresponds to the increase in size or mass of an individual bacterium while the "replicative rate" refers to its division capacity within a defined temporality. After a decades long hiatus, recent technical innovative approaches allow population growth and replicative rates heterogeneity monitoring at the single-cell level resuming in earnest. Among these techniques, the oldest and widely used is time-lapse microscopy, most recently combined with microfluidics. We also discuss recent fluorescence dilution methods informing only on replicative rates and best suited. Some new elegant single cell methods so far only sporadically used such as buoyant mass measurement and stable isotope probing have emerged. Overall, such tools are widely used to investigate and compare the growth and replicative rates of bacteria displaying drug-persistent behaviors to that of bacteria growing in specific ecological niches or collected from patients. In this review, we describe the current methods available, discussing both the type of queries these have been used to answer and the specific strengths and limitations of each method.
MeSH term(s)	Humans ; Microfluidics/methods ; Microscopy ; DNA Replication ; Bacteria
Language	English
Publishing date	2022-06-27
Publishing country	England
Document type	Review ; Journal Article
ZDB-ID	283740-7
ISSN	1574-6976 ; 0168-6445
ISSN (online)	1574-6976
ISSN	0168-6445
DOI	10.1093/femsre/fuac030
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Article ; Online: How Do the Virulence Factors of

Mattock, Emily / Blocker, Ariel J

Frontiers in cellular and infection microbiology

2017 Volume 7, Page(s) 64

Abstract: ... ...

Abstract	Shigella
MeSH term(s)	Adaptive Immunity ; Animals ; Bacterial Adhesion/genetics ; Bacterial Adhesion/immunology ; Dysentery, Bacillary/immunology ; Dysentery, Bacillary/metabolism ; Dysentery, Bacillary/microbiology ; Epithelium/immunology ; Epithelium/metabolism ; Epithelium/microbiology ; Epithelium/pathology ; Host-Pathogen Interactions/genetics ; Host-Pathogen Interactions/immunology ; Humans ; Immunity, Innate ; Immunomodulation ; Intestinal Mucosa/immunology ; Intestinal Mucosa/metabolism ; Intestinal Mucosa/microbiology ; Intestinal Mucosa/pathology ; Plasmids/genetics ; Shigella/physiology ; Type III Secretion Systems ; Virulence ; Virulence Factors/genetics ; Virulence Factors/metabolism
Chemical Substances	Type III Secretion Systems ; Virulence Factors
Language	English
Publishing date	2017
Publishing country	Switzerland
Document type	Journal Article ; Review
ZDB-ID	2619676-1
ISSN	2235-2988 ; 2235-2988
ISSN (online)	2235-2988
ISSN	2235-2988
DOI	10.3389/fcimb.2017.00064
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Article ; Online: In vitro antibiotic activity against intraosteoblastic Staphylococcus aureus: a narrative review of the literature.

Marro, Florian C / Abad, Lélia / Blocker, Ariel J / Laurent, Frédéric / Josse, Jérôme / Valour, Florent

The Journal of antimicrobial chemotherapy

2021 Volume 76, Issue 12, Page(s) 3091–3102

Abstract: Staphylococcus aureus - a major aetiological agent of bone and joint infection (BJI) - is associated with a high risk of relapse and chronicity, in part due to its ability to invade and persist in non-professional phagocytic bone cells such as ... ...

Abstract	Staphylococcus aureus - a major aetiological agent of bone and joint infection (BJI) - is associated with a high risk of relapse and chronicity, in part due to its ability to invade and persist in non-professional phagocytic bone cells such as osteoblasts. This intracellular reservoir protects S. aureus from the action of the immune system and most antibiotics. To date, the choice of antimicrobial strategies for BJI treatment mostly relies on standard susceptibility testing, bone penetration of antibiotics and their 'antibiofilm' activity. Despite the role of intracellular persistent S. aureus in the development of chronic infection, the ability of antibiotics to target the S. aureus intraosteoblastic reservoir is not considered in therapeutic choices but might represent a key determinant of treatment outcome. This review provides an overview of the intracellular pharmacokinetics of antistaphylococcal drugs used in the treatment of BJI and of their ability to target intraosteoblastic S. aureus. Thirteen studies focusing on the intraosteoblastic activity of antibiotics against S. aureus were reviewed, all relying on in vitro models of osteoblast infection. Despite varying incubation times, multiplicities of infection, bacterial strains, and the types of infected cell lines, rifamycins and fluoroquinolones remain the two most potent antimicrobial classes for intraosteoblastic S. aureus eradication, consistent with clinical data showing a superiority of this combination therapy in S. aureus orthopaedic device-related infections.
MeSH term(s)	Anti-Bacterial Agents/pharmacology ; Anti-Bacterial Agents/therapeutic use ; Humans ; Persistent Infection ; Rifamycins ; Staphylococcal Infections/drug therapy ; Staphylococcus aureus
Chemical Substances	Anti-Bacterial Agents ; Rifamycins
Language	English
Publishing date	2021-08-30
Publishing country	England
Document type	Journal Article ; Review
ZDB-ID	191709-2
ISSN	1460-2091 ; 0305-7453
ISSN (online)	1460-2091
ISSN	0305-7453
DOI	10.1093/jac/dkab301
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Article ; Online: MxiA, MxiC and IpaD Regulate Substrate Selection and Secretion Mode in the T3SS of Shigella flexneri.

Shen, Da-Kang / Blocker, Ariel J

PloS one

2016 Volume 11, Issue 5, Page(s) e0155141

Abstract: Type III secretion systems (T3SSs) are central virulence devices for many Gram-negative bacterial pathogens of humans, animals & plants. Upon physical contact with eukaryotic host cells, they translocate virulence-mediating proteins, known as effectors, ... ...

Abstract	Type III secretion systems (T3SSs) are central virulence devices for many Gram-negative bacterial pathogens of humans, animals & plants. Upon physical contact with eukaryotic host cells, they translocate virulence-mediating proteins, known as effectors, into them during infection. T3SSs are gated from the outside by host-cell contact and from the inside via two cytoplasmic negative regulators, MxiC and IpaD in Shigella flexneri, which together control the effector secretion hierarchy. Their absence leads to premature and increased secretion of effectors. Here, we investigated where and how these regulators act. We demonstrate that the T3SS inner membrane export apparatus protein MxiA plays a role in substrate selection. Indeed, using a genetic screen, we identified two amino acids located on the surface of MxiA's cytoplasmic region (MxiAC) which, when mutated, upregulate late effector expression and, in the case of MxiAI674V, also secretion. The cytoplasmic region of MxiA, but not MxiAN373D and MxiAI674V, interacts directly with the C-terminus of MxiC in a two-hybrid assay. Efficient T3S requires a cytoplasmic ATPase and the proton motive force (PMF), which is composed of the ΔΨ and the ΔpH. MxiA family proteins and their regulators are implicated in utilization of the PMF for protein export. However, our MxiA point mutants show similar PMF utilisation to wild-type, requiring primarily the ΔΨ. On the other hand, lack of MxiC or IpaD, renders the faster T3S seen increasingly dependent on the ΔpH. Therefore, MxiA, MxiC and IpaD act together to regulate substrate selection and secretion mode in the T3SS of Shigella flexneri.
MeSH term(s)	Bacterial Proteins/metabolism ; Bacterial Secretion Systems ; Mutant Proteins/metabolism ; Mutation/genetics ; Protein Binding ; Proton-Motive Force ; Shigella flexneri/metabolism ; Substrate Specificity ; Two-Hybrid System Techniques
Chemical Substances	Bacterial Proteins ; Bacterial Secretion Systems ; Mutant Proteins
Language	English
Publishing date	2016-05-12
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2267670-3
ISSN	1932-6203 ; 1932-6203
ISSN (online)	1932-6203
ISSN	1932-6203
DOI	10.1371/journal.pone.0155141
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Article: The COVID-19 pandemic: a threat to antimicrobial resistance containment.

Founou, Raspail C / Blocker, Ariel J / Noubom, Michel / Tsayem, Cedrice / Choukem, Siméon P / Dongen, Maarten Van / Founou, Luria L

Future science OA

2021 Volume 7, Issue 8, Page(s) FSO736

Abstract: As of 23 April 2021, the outbreak of COVID-19 claimed around 150 million confirmed cases with over 3 million deaths worldwide. Yet, an even more serious but silent pandemic, that of antimicrobial resistance (AMR), is likely complicating the outcome of ... ...

Abstract	As of 23 April 2021, the outbreak of COVID-19 claimed around 150 million confirmed cases with over 3 million deaths worldwide. Yet, an even more serious but silent pandemic, that of antimicrobial resistance (AMR), is likely complicating the outcome of COVID-19 patients. This study discusses the current knowledge on the emergence of the SARS-CoV-2 and highlights the likely contribution of the COVID-19 pandemic on the escalation of AMR. COVID-19 engenders extensive antibiotic overuse and misuse, and will undoubtedly and substantially increase AMR rates worldwide. Amid the expanding COVID-19 pandemic, policymakers should consider the hidden threat of AMR much more, which may well be enhanced through improper use of antibiotics to treat patients with severe COVID-19 infection.
Language	English
Publishing date	2021-06-10
Publishing country	England
Document type	Journal Article ; Review
ISSN	2056-5623
ISSN	2056-5623
DOI	10.2144/fsoa-2021-0012
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Article ; Online: The COVID-19 pandemic

Raspail C Founou / Ariel J Blocker / Michel Noubom / Cedrice Tsayem / Siméon P Choukem / Maarten Van Dongen / Luria L Founou

Future Science OA, Vol 7, Iss

a threat to antimicrobial resistance containment

2021 Volume 8

Abstract	As of 23 April 2021, the outbreak of COVID-19 claimed around 150 million confirmed cases with over 3 million deaths worldwide. Yet, an even more serious but silent pandemic, that of antimicrobial resistance (AMR), is likely complicating the outcome of COVID-19 patients. This study discusses the current knowledge on the emergence of the SARS-CoV-2 and highlights the likely contribution of the COVID-19 pandemic on the escalation of AMR. COVID-19 engenders extensive antibiotic overuse and misuse, and will undoubtedly and substantially increase AMR rates worldwide. Amid the expanding COVID-19 pandemic, policymakers should consider the hidden threat of AMR much more, which may well be enhanced through improper use of antibiotics to treat patients with severe COVID-19 infection.
Keywords	antimicrobial resistance ; antimicrobial stewardship ; COVID-19 pandemic ; COVID-19 vaccines ; SARS-CoV-2 ; Medicine ; R ; Medicine (General) ; R5-920
Language	English
Publishing date	2021-09-01T00:00:00Z
Publisher	Future Science Ltd
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: MxiA, MxiC and IpaD Regulate Substrate Selection and Secretion Mode in the T3SS of Shigella flexneri.

Da-Kang Shen / Ariel J Blocker

PLoS ONE, Vol 11, Iss 5, p e

2016 Volume 0155141

Abstract	Type III secretion systems (T3SSs) are central virulence devices for many Gram-negative bacterial pathogens of humans, animals & plants. Upon physical contact with eukaryotic host cells, they translocate virulence-mediating proteins, known as effectors, into them during infection. T3SSs are gated from the outside by host-cell contact and from the inside via two cytoplasmic negative regulators, MxiC and IpaD in Shigella flexneri, which together control the effector secretion hierarchy. Their absence leads to premature and increased secretion of effectors. Here, we investigated where and how these regulators act. We demonstrate that the T3SS inner membrane export apparatus protein MxiA plays a role in substrate selection. Indeed, using a genetic screen, we identified two amino acids located on the surface of MxiA's cytoplasmic region (MxiAC) which, when mutated, upregulate late effector expression and, in the case of MxiAI674V, also secretion. The cytoplasmic region of MxiA, but not MxiAN373D and MxiAI674V, interacts directly with the C-terminus of MxiC in a two-hybrid assay. Efficient T3S requires a cytoplasmic ATPase and the proton motive force (PMF), which is composed of the ΔΨ and the ΔpH. MxiA family proteins and their regulators are implicated in utilization of the PMF for protein export. However, our MxiA point mutants show similar PMF utilisation to wild-type, requiring primarily the ΔΨ. On the other hand, lack of MxiC or IpaD, renders the faster T3S seen increasingly dependent on the ΔpH. Therefore, MxiA, MxiC and IpaD act together to regulate substrate selection and secretion mode in the T3SS of Shigella flexneri.
Keywords	Medicine ; R ; Science ; Q
Subject code	571 ; 570
Language	English
Publishing date	2016-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Characterization of soluble complexes of the Shigella flexneri type III secretion system ATPase.

Johnson, Steven / Blocker, Ariel

FEMS microbiology letters

2008 Volume 286, Issue 2, Page(s) 274–278

Abstract: The conserved ATPase of type III secretion systems is critical to the export of substrates through the apparatus. We present a characterization of the native T3SS ATPase, Spa47, from the cytoplasm of Shigella flexneri, demonstrating it to be in two ... ...

Abstract	The conserved ATPase of type III secretion systems is critical to the export of substrates through the apparatus. We present a characterization of the native T3SS ATPase, Spa47, from the cytoplasm of Shigella flexneri, demonstrating it to be in two distinct high-molecular-weight complexes with Spa33: MxiN and MxiK.
MeSH term(s)	Adenosine Triphosphatases/chemistry ; Adenosine Triphosphatases/isolation & purification ; Adenosine Triphosphatases/metabolism ; Chromatography, Affinity ; Chromatography, Gel ; Membrane Transport Proteins/chemistry ; Membrane Transport Proteins/isolation & purification ; Membrane Transport Proteins/metabolism ; Molecular Weight ; Protein Binding ; Shigella flexneri/enzymology
Chemical Substances	Membrane Transport Proteins ; Adenosine Triphosphatases (EC 3.6.1.-) ; Spa47 protein, Shigella flexneri (EC 3.6.1.-)
Language	English
Publishing date	2008-07-23
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	752343-9
ISSN	1574-6968 ; 0378-1097
ISSN (online)	1574-6968
ISSN	0378-1097
DOI	10.1111/j.1574-6968.2008.01284.x
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Article ; Online: The interaction of

Wolfson, Eliza B / Elvidge, Johanna / Tahoun, Amin / Gillespie, Trudi / Mantell, Judith / McAteer, Sean P / Rossez, Yannick / Paxton, Edith / Lane, Fiona / Shaw, Darren J / Gill, Andrew C / Stevens, Jo / Verkade, Paul / Blocker, Ariel / Mahajan, Arvind / Gally, David L

Microbiology (Reading, England)

2020 Volume 166, Issue 10, Page(s) 947–965

Abstract: Bacterial flagella have many established roles beyond swimming motility. Despite clear evidence of flagella-dependent adherence, the specificity of the ligands and mechanisms of binding are still debated. In this study, the molecular basis ... ...

Abstract	Bacterial flagella have many established roles beyond swimming motility. Despite clear evidence of flagella-dependent adherence, the specificity of the ligands and mechanisms of binding are still debated. In this study, the molecular basis of
MeSH term(s)	Actins/chemistry ; Actins/metabolism ; Actins/ultrastructure ; Animals ; Bacterial Adhesion ; Cell Membrane/metabolism ; Cell Membrane/microbiology ; Cell Membrane/pathology ; Cell Membrane/ultrastructure ; Cells, Cultured ; Cytoskeleton/metabolism ; Cytoskeleton/ultrastructure ; Escherichia coli O157/genetics ; Escherichia coli O157/metabolism ; Escherichia coli O157/physiology ; Flagella/genetics ; Flagella/metabolism ; Flagella/ultrastructure ; Host-Pathogen Interactions ; Humans ; Microscopy, Electron ; Mutation ; Polymerization ; Salmonella typhimurium/genetics ; Salmonella typhimurium/metabolism ; Salmonella typhimurium/physiology
Chemical Substances	Actins
Language	English
Publishing date	2020-07-06
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	1180712-x
ISSN	1465-2080 ; 1350-0872
ISSN (online)	1465-2080
ISSN	1350-0872
DOI	10.1099/mic.0.000959
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Article ; Online: Shigella IpaD has a dual role: signal transduction from the type III secretion system needle tip and intracellular secretion regulation.

Roehrich, A Dorothea / Guillossou, Enora / Blocker, Ariel J / Martinez-Argudo, Isabel

Molecular microbiology

2013 Volume 87, Issue 3, Page(s) 690–706

Abstract: Type III secretion systems (T3SSs) are protein injection devices essential for the interaction of many Gram-negative bacteria with eukaryotic cells. While Shigella assembles its T3SS when the environmental conditions are appropriate for invasion, ... ...

Abstract	Type III secretion systems (T3SSs) are protein injection devices essential for the interaction of many Gram-negative bacteria with eukaryotic cells. While Shigella assembles its T3SS when the environmental conditions are appropriate for invasion, secretion is only activated after physical contact with a host cell. First, the translocators are secreted to form a pore in the host cell membrane, followed by effectors which manipulate the host cell. Secretion activation is tightly controlled by conserved T3SS components: the needle tip proteins IpaD and IpaB, the needle itself and the intracellular gatekeeper protein MxiC. To further characterize the role of IpaD during activation, we combined random mutagenesis with a genetic screen to identify ipaD mutant strains unable to respond to host cell contact. Class II mutants have an overall defect in secretion induction. They map to IpaD's C-terminal helix and likely affect activation signal generation or transmission. The Class I mutant secretes translocators prematurely and is specifically defective in IpaD secretion upon activation. A phenotypically equivalent mutant was found in mxiC. We show that IpaD and MxiC act in the same intracellular pathway. In summary, we demonstrate that IpaD has a dual role and acts at two distinct locations during secretion activation.
MeSH term(s)	Antigens, Bacterial/genetics ; Antigens, Bacterial/metabolism ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Bacterial Secretion Systems ; DNA Mutational Analysis ; Gene Expression Regulation, Bacterial ; Models, Molecular ; Mutagenesis ; Mutant Proteins/genetics ; Mutant Proteins/metabolism ; Shigella flexneri/genetics ; Shigella flexneri/metabolism ; Shigella flexneri/pathogenicity ; Signal Transduction ; Virulence Factors/metabolism
Chemical Substances	Antigens, Bacterial ; Bacterial Proteins ; Bacterial Secretion Systems ; IpaD protein, Shigella flexneri ; Mutant Proteins ; Virulence Factors
Language	English
Publishing date	2013-01-11
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	619315-8
ISSN	1365-2958 ; 0950-382X
ISSN (online)	1365-2958
ISSN	0950-382X
DOI	10.1111/mmi.12124
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