Gastrointestinal Dissemination and Transmission of Staphylococcus aureus following Bacteremia

Mutations that alter virulence and antibiotic susceptibility arise and persist duringStaphylococcus aureusbacteremia. However, an experimental system demonstrating transmission following bacteremia has been lacking, and thus implications of within-host adaptation for between-host transmission are unknown. We report thatS. aureusdisseminates to the gastrointestinal tract of mice following intravenous injection and readily transmits to cohoused naive mice. Both intestinal dissemination and transmission were linked to the production of virulence factors based on gene deletion studies of thesaeandagrtwo-component systems. Furthermore, antimicrobial selection for antibiotic-resistantS. aureusdisplaced susceptibleS. aureusfrom the intestine of infected hosts, which led to the preferential transmission and dominance of antibiotic-resistant bacteria among cohoused untreated mice. These findings establish an animal model to investigate gastrointestinal dissemination and transmission ofS. aureusand suggest that adaptation during the course of systemic infection has implications beyond the level of a single host.

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Redox Balance via Lactate Dehydrogenase Is Important for Multiple Stress Resistance and Virulence in Enterococcus faecalis

Infection and Immunity ◽

10.1128/iai.01299-12 ◽

2013 ◽

Vol 81 (8) ◽

pp. 2662-2668 ◽

Cited By ~ 13

Author(s):

Nosheen Fatima Rana ◽

Nicolas Sauvageot ◽

Jean-Marie Laplace ◽

YinYin Bao ◽

Ingolf Nes ◽

...

Keyword(s):

Lactate Dehydrogenase ◽

Enterococcus Faecalis ◽

Drug Target ◽

Systemic Infection ◽

Opportunistic Pathogen ◽

Redox Balance ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Content Type ◽

Hostile Environments

ABSTRACTEnterococcus faecalisis a highly stress resistant opportunistic pathogen. The intrinsic ruggedness of this bacterium is supposed to be the basis of its capacity to colonize the hostile environments of hospitals and to cause several kinds of infections. We show in this work that general resistance to very different environmental stresses depends on the ability ofE. faecalisto maintain redox balance via lactate dehydrogenase (LDH). Furthermore, LDH-deficient mutants are less successful than the wild type at colonizing host organs in a murine model of systemic infection. Taken together, our results, as well as those previously published forStaphylococcus aureus(A. R. Richardson, S. J. Libby, and F. C. Fang, Science 319:1672–1676, 2008), identify LDH as an attractive drug target. These drugs may have additional applications, as in the fight against glycopeptide antibiotic-resistant bacteria and even cancer.

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Comparative Mechanistic Studies of Brilacidin, Daptomycin, and the Antimicrobial Peptide LL16

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02955-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5136-5145 ◽

Cited By ~ 85

Author(s):

Bruk Mensa ◽

Gabriella L. Howell ◽

Richard Scott ◽

William F. DeGrado

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Peptide ◽

Stress Responses ◽

Protein Misfolding ◽

Transcriptional Profiling ◽

Gram Positive ◽

Cationic Antimicrobial Peptide ◽

Content Type ◽

Component Systems ◽

Two Component Systems

ABSTRACTBrilacidin (PMX30063) has shown potent bactericidal activity against drug-resistant and -susceptible strains of multiple Gram-negative and Gram-positive pathogens. In this study, we demonstrate that brilacidin causes membrane depolarization in the Gram-positive bacteriumStaphylococcus aureus, to an extent comparable to that caused by the lipopeptidic drug daptomycin. Transcriptional profiling ofStaphylococcus aureusby deep sequencing shows that the global response to brilacidin treatment is well correlated to those of treatment with daptomycin and the cationic antimicrobial peptide LL37 and mostly indicates abrogation of cell wall and membrane functions. Furthermore, the upregulation of various chaperones and proteases by brilacidin and daptomycin indicates that cytoplasmic protein misfolding stress may be a contributor to the mechanism of action of these drugs. These stress responses were orchestrated mainly by three two-component systems, GraSR, VraSR, and NsaSR, which have been implicated in virulence and drug resistance against other clinically available antibiotics.

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Regulation of virulence and β-lactamase gene expression in Staphylococcus aureus isolates: cooperation of two-component systems in bloodstream superbugs

BMC Microbiology ◽

10.1186/s12866-021-02257-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Sanaz Dehbashi ◽

Hamed Tahmasebi ◽

Behrouz Zeyni ◽

Mohammad Reza Arabestani

Keyword(s):

Staphylococcus Aureus ◽

Real Time ◽

Real Time Pcr ◽

Quantitative Real Time Pcr ◽

Gene Expressions ◽

Resistance Development ◽

Component Systems ◽

Two Component ◽

Two Component Systems ◽

Lactamase Gene

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA)-bloodstream infections (BSI) are predominantly seen in the hospital or healthcare-associated host. Nevertheless, the interactions of virulence factor (VFs) regulators and β-lactam resistance in MRSA-BSI are unclear. This study aims to characterize the molecular relationship of two-component systems of VFs and the expression of the β-lactamase gene in MRSA-BSI isolates. In this study, 639 samples were collected from BSI and identified by phenotypic methods. We performed extensive molecular characterization, including SCCmec type, agr type, VFs gene profiles determinations, and MLST on isolates. Also, a quantitative real-time PCR (q-RT PCR) assay was developed for identifying the gene expressions. Results Ninety-one (91) S. aureus and 61 MRSA (67.0%) strains were detected in BSI samples. The presence of VFs and SCCmec genes in MRSA isolates were as follows: tst (31.4%), etA (18.0%), etB (8.19%), lukS-PVL (31.4%), lukF-PV (18.0%), lukE-lukD (16.3%), edin (3.2%), hla (16.3%), hlb (18.0%), hld (14.7%), hlg (22.9%), SCCmecI (16.3%), SCCmecII (22.9%), SCCmecIII (36.0%), SCCmecIV (21.3%), and SCCmecV (16.3%). Quantitative real-time PCR showed overexpression of mecRI and mecI in the toxigenic isolates. Moreover, RNAIII and sarA genes were the highest expressions of MRSA strains. The multi-locus sequence typing data confirmed a high prevalence of CC5, CC8, and CC30. However, ST30, ST22, and ST5 were the most prevalent in the resistant and toxigenic strains. Conclusion We demonstrated that although regulation of β-lactamase gene expressions is a significant contributor to resistance development, two-component systems also influence antibiotic resistance development in MRSA-BSI isolates. This indicates that resistant strains might have pathogenic potential. We also confirmed that some MLST types are more successful colonizers with a potential for MRSA-BSI.

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A Putative Cro-Like Repressor Contributes to Arylomycin Resistance in Staphylococcus aureus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04597-14 ◽

2015 ◽

Vol 59 (6) ◽

pp. 3066-3074 ◽

Cited By ~ 9

Author(s):

Arryn Craney ◽

Floyd E. Romesberg

Keyword(s):

Staphylococcus Aureus ◽

Ex Vivo ◽

Transcriptional Regulator ◽

Signal Peptidase ◽

Health Concern ◽

Resistant Bacteria ◽

Type I ◽

Wall Teichoic Acid ◽

Content Type ◽

Wide Range

ABSTRACTAntibiotic-resistant bacteria are a significant public health concern and motivate efforts to develop new classes of antibiotics. One such class of antibiotics is the arylomycins, which target type I signal peptidase (SPase), the enzyme responsible for the release of secreted proteins from their N-terminal leader sequences. Despite the essentiality, conservation, and relative accessibility of SPase, the activity of the arylomycins is limited against some bacteria, including the important human pathogenStaphylococcus aureus. To understand the origins of the limited activity againstS. aureus, we characterized the susceptibility of a panel of strains to two arylomycin derivatives, arylomycin A-C16and its more potent analog arylomycin M131. We observed a wide range of susceptibilities to the two arylomycins and found that resistant strains were sensitized by cotreatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. To further understand howS. aureusresponds to the arylomycins, we profiled the transcriptional response ofS. aureusNCTC 8325 to growth-inhibitory concentrations of arylomycin M131 and found that it upregulates the cell wall stress stimulon (CWSS) and an operon consisting of a putative transcriptional regulator and three hypothetical proteins. Interestingly, we found that mutations in the putative transcriptional regulator are correlated with resistance, and selection for resistanceex vivodemonstrated that mutations in this gene are sufficient for resistance. The results begin to elucidate howS. aureuscopes with secretion stress and how it evolves resistance to the inhibition of SPase.

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Manipulation of Autophagy in Phagocytes Facilitates Staphylococcus aureus Bloodstream Infection

Infection and Immunity ◽

10.1128/iai.00358-15 ◽

2015 ◽

Vol 83 (9) ◽

pp. 3445-3457 ◽

Cited By ~ 43

Author(s):

Kate M. O'Keeffe ◽

Mieszko M. Wilk ◽

John M. Leech ◽

Alison G. Murphy ◽

Maisem Laabei ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Systemic Infection ◽

Critical Factor ◽

Intracellular Survival ◽

Autophagic Flux ◽

Content Type ◽

Bactericidal Effects ◽

Staphylococcus Aureus Bloodstream Infection ◽

Direct Killing

The capacity for intracellular survival within phagocytes is likely a critical factor facilitating the dissemination ofStaphylococcus aureusin the host. To date, the majority of work onS. aureus-phagocyte interactions has focused on neutrophils and, to a lesser extent, macrophages, yet we understand little about the role played by dendritic cells (DCs) in the direct killing of this bacterium. Using bone marrow-derived DCs (BMDCs), we demonstrate for the first time that DCs can effectively killS. aureusbut that certain strains ofS. aureushave the capacity to evade DC (and macrophage) killing by manipulation of autophagic pathways. Strains with high levels of Agr activity were capable of causing autophagosome accumulation, were not killed by BMDCs, and subsequently escaped from the phagocyte, exerting significant cytotoxic effects. Conversely, strains that exhibited low levels of Agr activity failed to accumulate autophagosomes and were killed by BMDCs. Inhibition of the autophagic pathway by treatment with 3-methyladenine restored the bactericidal effects of BMDCs. Using anin vivomodel of systemic infection, we demonstrated that the ability ofS. aureusstrains to evade phagocytic cell killing and to survive temporarily within phagocytes correlated with persistence in the periphery and that this effect is critically Agr dependent. Taken together, our data suggest that strains ofS. aureusexhibiting high levels of Agr activity are capable of blocking autophagic flux, leading to the accumulation of autophagosomes. Within these autophagosomes, the bacteria are protected from phagocytic killing, thus providing an intracellular survival niche within professional phagocytes, which ultimately facilitates dissemination.

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Hypochlorite-Activated Fluorescence Emission and Antibacterial Activities of Imidazole Derivatives for Biological Applications

Frontiers in Chemistry ◽

10.3389/fchem.2021.713078 ◽

2021 ◽

Vol 9 ◽

Author(s):

Thanh Chung Pham ◽

Van-Nghia Nguyen ◽

Yeonghwan Choi ◽

Dongwon Kim ◽

Ok-Sang Jung ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Stokes Shift ◽

Fluorescence Emission ◽

Antibacterial Activities ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Fluorogenic Probe ◽

High Fluorescence

The ability to detect hypochlorite (HOCl/ClO−) in vivo is of great importance to identify and visualize infection. Here, we report the use of imidazoline-2-thione (R1SR2) probes, which act to both sense ClO− and kill bacteria. The N2C=S moieties can recognize ClO− among various typical reactive oxygen species (ROS) and turn into imidazolium moieties (R1IR2) via desulfurization. This was observed through UV–vis absorption and fluorescence emission spectroscopy, with a high fluorescence emission quantum yield (ՓF = 43–99%) and large Stokes shift (∆v∼115 nm). Furthermore, the DIM probe, which was prepared by treating the DSM probe with ClO−, also displayed antibacterial efficacy toward not only Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) but also methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum ß-lactamase–producing Escherichia coli (ESBL-EC), that is, antibiotic-resistant bacteria. These results suggest that the DSM probe has great potential to carry out the dual roles of a fluorogenic probe and killer of bacteria.

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Antibacterial Peptides Resistance in Staphylococcus aureus: Various Mechanisms and the Association with Pathogenicity

Genes ◽

10.3390/genes12101527 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1527

Author(s):

Miki Kawada-Matsuo ◽

Mi Nguyen-Tra Le ◽

Hitoshi Komatsuzawa

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Peptides ◽

Antibacterial Peptides ◽

Low Concentrations ◽

Component Systems ◽

Two Component Systems ◽

Resistant Strains ◽

Resistant Mutants ◽

High Concentrations

Staphylococcus aureus is a bacterium that mainly colonizes the nasal cavity and skin. To colonize the host, it is necessary for S. aureus to resist many antibacterial factors derived from human and commensal bacteria. Among them are the bacteria-derived antimicrobial peptides (AMPs) called bacteriocins. It was reported that some two-component systems (TCSs), which are signal transduction systems specific to bacteria, are involved in the resistance to several bacteriocins in S. aureus. However, the TCS-mediated resistance is limited to relatively low concentrations of bacteriocins, while high concentrations of bacteriocins still exhibit antibacterial activity against S. aureus. To determine whether we could obtain highly bacteriocin-resistant mutants, we tried to isolate highly nisin A-resistant mutants by exposing the cells to sub-minimum inhibitory concentrations (MICs) of nisin A. Nisin A is one of the bacteriocins produced by Lactococcus lactis and is utilized as a food preservative worldwide. Finally, we obtained highly nisin A-resistant mutants with mutations in one TCS, BraRS, and in PmtR, which is involved in the expression of pmtABCD. Notably, some highly resistant strains also showed increased pathogenicity. Based on our findings, this review provides up-to-date information on the role of TCSs in the susceptibility to antibacterial peptides. Additionally, the mechanism for high antimicrobial peptides resistance and its association with pathogenicity in S. aureus is elucidated.

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Elucidation of Regulatory Modes for Five Two-Component Systems in Escherichia coli Reveals Novel Relationships

mSystems ◽

10.1128/msystems.00980-20 ◽

2020 ◽

Vol 5 (6) ◽

Author(s):

Kumari Sonal Choudhary ◽

Julia A. Kleinmanns ◽

Katherine Decker ◽

Anand V. Sastry ◽

Ye Gao ◽

...

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Target Gene ◽

Target Genes ◽

Rna Seq ◽

Content Type ◽

E Coli ◽

Component Systems ◽

Two Component ◽

Two Component Systems

ABSTRACT Escherichia coli uses two-component systems (TCSs) to respond to environmental signals. TCSs affect gene expression and are parts of E. coli’s global transcriptional regulatory network (TRN). Here, we identified the regulons of five TCSs in E. coli MG1655: BaeSR and CpxAR, which were stimulated by ethanol stress; KdpDE and PhoRB, induced by limiting potassium and phosphate, respectively; and ZraSR, stimulated by zinc. We analyzed RNA-seq data using independent component analysis (ICA). ChIP-exo data were used to validate condition-specific target gene binding sites. Based on these data, we do the following: (i) identify the target genes for each TCS; (ii) show how the target genes are transcribed in response to stimulus; and (iii) reveal novel relationships between TCSs, which indicate noncognate inducers for various response regulators, such as BaeR to iron starvation, CpxR to phosphate limitation, and PhoB and ZraR to cell envelope stress. Our understanding of the TRN in E. coli is thus notably expanded. IMPORTANCE E. coli is a common commensal microbe found in the human gut microenvironment; however, some strains cause diseases like diarrhea, urinary tract infections, and meningitis. E. coli’s two-component systems (TCSs) modulate target gene expression, especially related to virulence, pathogenesis, and antimicrobial peptides, in response to environmental stimuli. Thus, it is of utmost importance to understand the transcriptional regulation of TCSs to infer bacterial environmental adaptation and disease pathogenicity. Utilizing a combinatorial approach integrating RNA sequencing (RNA-seq), independent component analysis, chromatin immunoprecipitation coupled with exonuclease treatment (ChIP-exo), and data mining, we suggest five different modes of TCS transcriptional regulation. Our data further highlight noncognate inducers of TCSs, which emphasizes the cross-regulatory nature of TCSs in E. coli and suggests that TCSs may have a role beyond their cognate functionalities. In summary, these results can lead to an understanding of the metabolic capabilities of bacteria and correctly predict complex phenotype under diverse conditions, especially when further incorporated with genome-scale metabolic models.

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Fighting Antibiotic-Resistant Klebsiella pneumoniae with “Sweet” Immune Targets

mBio ◽

10.1128/mbio.00874-18 ◽

2018 ◽

Vol 9 (3) ◽

Cited By ~ 4

Author(s):

Roberto Adamo ◽

Immaculada Margarit

Keyword(s):

Klebsiella Pneumoniae ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Therapeutic Approaches ◽

Antibiotic Resistant ◽

Content Type ◽

Carbapenem Resistant ◽

Surface Polysaccharides ◽

Resistant Strains ◽

Murine Monoclonal Antibodies

ABSTRACT Antibiotics and vaccines have greatly impacted human health in the last century by dramatically reducing the morbidity and mortality associated with infectious diseases. The recent challenge posed by the emergence of multidrug-resistant bacteria could possibly be addressed by novel immune prophylactic and therapeutic approaches. Among the newly threatening pathogens, Klebsiella pneumoniae is particularly worrisome in the nosocomial setting, and its surface polysaccharides are regarded as promising antigen candidates. The majority of Klebsiella carbapenem-resistant strains belong to the sequence type 158 (ST258) lineage, with two main clades expressing capsular polysaccharides CPS1 and CPS2. In a recent article, S. D. Kobayashi and colleagues (mBio 9:e00297-18, 2018, https://doi.org/10.1128/mBio.00297-18) show that CPS2-specific IgGs render ST258 clade 2 bacteria more sensitive to human serum and phagocytic killing. E. Diago-Navarro et al. (mBio 9:e00091-18, 2018, https://doi.org/10.1128/mBio.00091-18) generated two murine monoclonal antibodies recognizing distinct glycotopes of CPS2 that presented functional activity against multiple ST258 strains. These complementary studies represent a step toward the control of this dangerous pathogen.

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HAMLET, a Protein Complex from Human Milk, Has Bactericidal Activity and Enhances the Activity of Antibiotics against Pathogenic Streptococci

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01193-19 ◽

2019 ◽

Vol 63 (12) ◽

Cited By ~ 5

Author(s):

Feiruz Alamiri ◽

Kristian Riesbeck ◽

Anders P. Hakansson

Keyword(s):

Human Milk ◽

Bactericidal Activity ◽

Combination Treatment ◽

Bacterial Species ◽

Penicillin G ◽

Resistant Bacteria ◽

Tumoricidal Activity ◽

Antibiotic Resistant ◽

Content Type ◽

Transport Inhibitors

ABSTRACT HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a protein-lipid complex derived from human milk that was first described for its tumoricidal activity. Later studies showed that HAMLET also has direct bactericidal activity against select species of bacteria, with highest activity against Streptococcus pneumoniae. Additionally, HAMLET in combination with various antimicrobial agents can make a broad range of antibiotic-resistant bacterial species sensitive to antibiotics. Here, we show that HAMLET has direct antibacterial activity not only against pneumococci but also against Streptococcus pyogenes (group A streptococci [GAS]) and Streptococcus agalactiae (group B streptococci [GBS]). As with pneumococci, HAMLET treatment of GAS and GBS resulted in depolarization of the bacterial membrane, followed by membrane permeabilization and death, which was able to be inhibited by calcium and sodium transport inhibitors. Treatment of clinical antibiotic-resistant isolates of S. pneumoniae, GAS, and GBS with sublethal concentrations of HAMLET in combination with antibiotics decreased the MICs of the antibiotics into the sensitive range. This effect could also be blocked by ion transport inhibitors, suggesting that HAMLET’s bactericidal and combination treatment effects used similar mechanisms. Finally, we show that HAMLET potentiated the effects of erythromycin against erythromycin-resistant bacteria more effectively than penicillin G potentiated killing bacteria resistant to erythromycin. These results show that HAMLET effectively (i) kills three different species of pathogenic streptococci by similar mechanisms and also (ii) potentiates the activities of macrolides and lincosamides more effectively than combination treatment with beta-lactams. These findings suggest a potential therapeutic role for HAMLET in repurposing antibiotics currently causing treatment failures in patients.

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