Genomic fitness profiling of Acinetobacter baumannii reveals modes of action for common biocides and mechanisms of biocide-antibiotic antagonism

Abstract Biocides, such as antiseptics and disinfectants, are used ubiquitously for hygiene in households and for life-saving infection control in hospitals. An increasing concern is that the widespread use of biocides may contribute to the emergence and spread of multidrug-resistant bacteria. We performed transposon directed insertion site sequencing (TraDIS) to identify genes and key cellular pathways of the multidrug resistant nosocomial pathogen Acinetobacter baumannii, that affect host fitness during exposure to a panel of ten structurally-diverse and clinically-relevant biocides: silver nitrate, benzalkonium, cetyltrimethylammonium bromide (CTAB), chlorhexidine, triclosan, chloroxylenol, polyvidone iodine, bleach, glutaraldehyde and ethanol. Multiple genes encoding proteins localised either in the cell envelope or in the cytoplasm were shown to affect biocide susceptibility. These proteins are involved in multiple processes including fatty acid biogenesis, multidrug efflux, the tricarboxylic acid cycle, cell respiration and cell division, suggesting that these biocides may have intracellular targets in addition to their known effects on the cell envelope. Based on the importance of cell respiration genes for A. baumannii fitness on biocides, we proposed and confirmed that apart from triclosan, the other 9 biocides at sub-inhibitory concentration can dissipate the membrane potential and lead to A. baumannii tolerance to antibiotics that have intracellular targets. Our results support the concern that residual biocides in clinical or community environments can promote the development of antibiotic resistance in pathogenic bacteria.

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Translocation of non-lytic antimicrobial peptides and bacteria penetrating peptides across the inner membrane of the bacterial envelope

Current Genetics ◽

10.1007/s00294-021-01217-9 ◽

2021 ◽

Author(s):

Jakob Frimodt-Møller ◽

Christopher Campion ◽

Peter E. Nielsen ◽

Anders Løbner-Olesen

Keyword(s):

Antimicrobial Peptides ◽

Pathogenic Bacteria ◽

Cytoplasmic Membrane ◽

Cell Envelope ◽

Multidrug Resistant ◽

Great Promise ◽

Strong Focus ◽

Gene Transcripts ◽

Phosphorodiamidate Morpholino Oligomers ◽

Intracellular Targets

AbstractThe increase in multidrug-resistant pathogenic bacteria has become a problem worldwide. Currently there is a strong focus on the development of novel antimicrobials, including antimicrobial peptides (AMP) and antimicrobial antisense agents. While the majority of AMP have membrane activity and kill bacteria through membrane disruption, non-lytic AMP are non-membrane active, internalize and have intracellular targets. Antimicrobial antisense agents such as peptide nucleic acids (PNA) and phosphorodiamidate morpholino oligomers (PMO), show great promise as novel antibacterial agents, killing bacteria by inhibiting translation of essential target gene transcripts. However, naked PNA and PMO are unable to translocate across the cell envelope of bacteria, to reach their target in the cytosol, and are conjugated to bacteria penetrating peptides (BPP) for cytosolic delivery. Here, we discuss how non-lytic AMP and BPP-PMO/PNA conjugates translocate across the cytoplasmic membrane via receptor-mediated transport, such as the cytoplasmic membrane transporters SbmA, MdtM/YjiL, and/or YgdD, or via a less well described autonomous process.

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Time-Resolved Transcriptional Profiling of Epithelial Cells Infected by Intracellular Acinetobacter baumannii

Microorganisms ◽

10.3390/microorganisms9020354 ◽

2021 ◽

Vol 9 (2) ◽

pp. 354

Author(s):

Nuria Crua Asensio ◽

Javier Macho Rendón ◽

Marc Torrent Burgas

Keyword(s):

Acinetobacter Baumannii ◽

Transcriptional Profiling ◽

Multidrug Resistant ◽

Host Cells ◽

Resistant Bacteria ◽

Multidrug Resistant Bacteria ◽

Time Resolved ◽

Antibiotic Resistant ◽

Common Features ◽

Profile Changes

The rise in the number of antibiotic-resistant bacteria has become a serious threat to health, making it important to identify, characterize and optimize new molecules to help us to overcome the infections they cause. It is well known that Acinetobacter baumannii has a significant capacity to evade the actions of antibacterial drugs, leading to its emergence as one of the bacteria responsible for hospital and community-acquired infections. Nonetheless, how this pathogen infects and survives inside the host cell is unclear. In this study, we analyze the time-resolved transcriptional profile changes observed in human epithelial HeLa cells after infection by A. baumannii, demonstrating how it survives in host cells and starts to replicate 4 h post infection. These findings were achieved by sequencing RNA to obtain a set of Differentially Expressed Genes (DEGs) to understand how bacteria alter the host cells’ environment for their own benefit. We also determine common features observed in this set of genes and identify the protein–protein networks that reveal highly-interacted proteins. The combination of these findings paves the way for the discovery of new antimicrobial candidates for the treatment of multidrug-resistant bacteria.

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Bacteriophages: the possible solution to treat infections caused by pathogenic bacteria

Canadian Journal of Microbiology ◽

10.1139/cjm-2017-0030 ◽

2017 ◽

Vol 63 (11) ◽

pp. 865-879 ◽

Cited By ~ 26

Author(s):

Ayman El-Shibiny ◽

Salma El-Sahhar

Keyword(s):

Bacterial Infections ◽

Pathogenic Bacteria ◽

Phage Therapy ◽

Multidrug Resistant ◽

Clinical Applications ◽

Western World ◽

Resistant Bacteria ◽

Vaccine Production ◽

Bacterial Populations ◽

Antibiotic Resistant

Since their discovery in 1915, bacteriophages have been used to treat bacterial infections in animals and humans because of their unique ability to infect their specific bacterial hosts without affecting other bacterial populations. The research carried out in this field throughout the 20th century, largely in Georgia, part of USSR and Poland, led to the establishment of phage therapy protocols. However, the discovery of penicillin and sulfonamide antibiotics in the Western World during the 1930s was a setback in the advancement of phage therapy. The misuse of antibiotics has reduced their efficacy in controlling pathogens and has led to an increase in the number of antibiotic-resistant bacteria. As an alternative to antibiotics, bacteriophages have become a topic of interest with the emergence of multidrug-resistant bacteria, which are a threat to public health. Recent studies have indicated that bacteriophages can be used indirectly to detect pathogenic bacteria or directly as biocontrol agents. Moreover, they can be used to develop new molecules for clinical applications, vaccine production, drug design, and in the nanomedicine field via phage display.

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Antibiotic adjuvants: a promising approach to combat multidrug resistant bacteria

Current Drug Targets ◽

10.2174/1389450122666210120084406 ◽

2021 ◽

Vol 22 ◽

Author(s):

Namita Sharma ◽

Anil K. Chhillar ◽

Sweety Dahiya ◽

Pooja Choudhary ◽

Aruna Punia ◽

...

Keyword(s):

Drug Targets ◽

Pathogenic Bacteria ◽

Antibacterial Agents ◽

Bacterial Resistance ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Antibacterial Drugs ◽

Effective Strategies ◽

The Impact ◽

Emergence Of Resistance

The escalating emergence and prevalence of infections caused by multi-drug resistant (MDR) pathogenic bacteria accentuate the crucial need to develop novel and effectual therapeutic strategies to control this threat. Recent past surprisingly indicates a staggering decline in effective strategies against MDR. Different approaches have been employed to minimize the effect of resistance but the question still lingers over the astounding number of drugs already tried and tested to no avail, furthermore, the detection of new drug targets and the action of new antibacterial agents against already existing drug targets also complicate the condition. Antibiotic adjuvants are considered as one such promising approach for overcoming the bacterial resistance. Adjuvants can potentiate the action of generally adopted antibacterial drugs against MDR bacterial pathogens either by minimizing the impact and emergence of resistance or improving the action of antibacterial drugs. This review provides an overview of mechanism of antibiotic resistance, main types of adjuvants and their mode of action, achievements and progression.

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Antimicrobial Activity of Five Apitoxins from Apis mellifera on Two Common Foodborne Pathogens

Antibiotics ◽

10.3390/antibiotics9070367 ◽

2020 ◽

Vol 9 (7) ◽

pp. 367

Author(s):

Alexandre Lamas ◽

Vicente Arteaga ◽

Patricia Regal ◽

Beatriz Vázquez ◽

José Manuel Miranda ◽

...

Keyword(s):

Antimicrobial Activity ◽

Foodborne Pathogens ◽

Food Chain ◽

Pathogenic Bacteria ◽

Inhibitory Concentration ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Public Health Challenges ◽

Alternative Agent ◽

Potential Alternative

Antimicrobial resistance is one of today’s major public health challenges. Infections caused by multidrug-resistant bacteria have been responsible for an increasing number of deaths in recent decades. These resistant bacteria are also a concern in the food chain, as bacteria can resist common biocides used in the food industry and reach consumers. As a consequence, the search for alternatives to common antimicrobials by the scientific community has intensified. Substances obtained from nature have shown great potential as new sources of antimicrobial activity. The aim of this study was to evaluate the antimicrobial activity of five bee venoms, also called apitoxins, against two common foodborne pathogens. A total of 50 strains of the Gram-negative pathogen Salmonella enterica and 8 strains of the Gram-positive pathogen Listeria monocytogenes were tested. The results show that the minimum inhibitory concentration (MIC) values were highly influenced by the bacterial genus. The MIC values ranged from 256 to 1024 µg/mL in S. enterica and from 16 to 32 µg/mL in L. monocytogenes. The results of this study demonstrate that apitoxin is a potential alternative agent against common foodborne pathogens, and it can be included in the development of new models to inhibit the growth of pathogenic bacteria in the food chain.

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Antimicrobial Resistance in Bacterial Pathogens and Detection of Carbapenemases in Klebsiella pneumoniae Isolates from Hospital Wastewater

Antibiotics ◽

10.3390/antibiotics8030085 ◽

2019 ◽

Vol 8 (3) ◽

pp. 85 ◽

Cited By ~ 5

Author(s):

Hercules Sakkas ◽

Petros Bozidis ◽

Afrodite Ilia ◽

George Mpekoulis ◽

Chrissanthy Papadopoulou

Keyword(s):

Staphylococcus Aureus ◽

Klebsiella Pneumoniae ◽

Pathogenic Bacteria ◽

Multidrug Resistant ◽

Rapid Identification ◽

Diffusion Method ◽

Resistant Bacteria ◽

Screening Methods ◽

Extended Spectrum Beta Lactamase ◽

Vancomycin Resistant

During a six-month period (October 2017–March 2018), the prevalence and susceptibility of important pathogenic bacteria isolated from 12 hospital raw sewage samples in North Western Greece was investigated. The samples were analyzed for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum beta-lactamase (ESBL) producing Escherichia coli, carbapenemase-producing Klebsiella pneumoniae (CKP), and multidrug-resistant Pseudomonas aeruginosa. Antimicrobial susceptibility testing was performed using the agar diffusion method according to the recommendations of the Clinical and Laboratory Standards Institute. The diversity of carbapenemases harboring K. pneumoniae was examined by two phenotyping screening methods (modified Hodge test and combined disk test), a new immunochromatographic rapid assay (RESIST-4 O.K.N.V.) and a polymerase chain reaction (PCR). The results demonstrated the prevalence of MRSA, vancomycin-resistant Staphylococcus aureus (VRSA), VRE, and CKP in the examined hospital raw sewage samples. In addition, the aforementioned methods which are currently used in clinical laboratories for the rapid identification and detection of resistant bacteria and genes, performed sufficiently to provide reliable results in terms of accuracy and efficiency.

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The Acinetobacter baumannii Znu System Overcomes Host-Imposed Nutrient Zinc Limitation

Infection and Immunity ◽

10.1128/iai.00746-19 ◽

2019 ◽

Vol 87 (12) ◽

Cited By ~ 4

Author(s):

Laura E. Hesse ◽

Zachery R. Lonergan ◽

William N. Beavers ◽

Eric P. Skaar

Keyword(s):

Acinetobacter Baumannii ◽

Defense Mechanisms ◽

Pathogenic Bacteria ◽

Bacterial Pathogen ◽

Multidrug Resistant ◽

World Health ◽

Content Type ◽

Nutritional Immunity ◽

Essential Nutrient ◽

Health Organization

ABSTRACT Acinetobacter baumannii is an opportunistic bacterial pathogen capable of causing a variety of infections, including pneumonia, sepsis, wound, and burn infections. A. baumannii is an increasing threat to public health due to the prevalence of multidrug-resistant strains, leading the World Health Organization to declare A. baumannii a “Priority 1: Critical” pathogen, for which the development of novel antimicrobials is desperately needed. Zinc (Zn) is an essential nutrient that pathogenic bacteria, including A. baumannii, must acquire from their hosts in order to survive. Consequently, vertebrate hosts have defense mechanisms to sequester Zn from invading bacteria through a process known as nutritional immunity. Here, we describe a Zn uptake (Znu) system that enables A. baumannii to overcome this host-imposed Zn limitation. The Znu system consists of an inner membrane ABC transporter and an outer membrane TonB-dependent receptor. Strains of A. baumannii lacking any individual Znu component are unable to grow in Zn-starved conditions, including in the presence of the host nutritional immunity protein calprotectin. The Znu system contributes to Zn-limited growth by aiding directly in the uptake of Zn into A. baumannii cells and is important for pathogenesis in murine models of A. baumannii infection. These results demonstrate that the Znu system allows A. baumannii to subvert host nutritional immunity and acquire Zn during infection.

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The Concerted Action of Two B3-Like Prophage Genes Excludes Superinfecting Bacteriophages by Blocking DNA Entry into Pseudomonas aeruginosa

Journal of Virology ◽

10.1128/jvi.00953-20 ◽

2020 ◽

Vol 94 (15) ◽

Author(s):

Marco Antonio Carballo-Ontiveros ◽

Adrián Cazares ◽

Pablo Vinuesa ◽

Luis Kameyama ◽

Gabriel Guarneros

Keyword(s):

Pseudomonas Aeruginosa ◽

Pathogenic Bacteria ◽

Phage Therapy ◽

Alternative Therapy ◽

Multidrug Resistant ◽

Open Reading Frames ◽

Resistant Bacteria ◽

Content Type ◽

Secondary Infections ◽

Genes Encoding

ABSTRACT In this study, we describe seven vegetative phage genomes homologous to the historic phage B3 that infect Pseudomonas aeruginosa. Like other phage groups, the B3-like group contains conserved (core) and variable (accessory) open reading frames (ORFs) grouped at fixed regions in their genomes; however, in either case, many ORFs remain without assigned functions. We constructed lysogens of the seven B3-like phages in strain Ps33 of P. aeruginosa, a novel clinical isolate, and assayed the exclusion phenotype against a variety of temperate and virulent superinfecting phages. In addition to the classic exclusion conferred by the phage immunity repressor, the phenotype observed in B3-like lysogens suggested the presence of other exclusion genes. We set out to identify the genes responsible for this exclusion phenotype. Phage Ps56 was chosen as the study subject since it excluded numerous temperate and virulent phages. Restriction of the Ps56 genome, cloning of several fragments, and resection of the fragments that retained the exclusion phenotype allowed us to identify two core ORFs, so far without any assigned function, as responsible for a type of exclusion. Neither gene expressed separately from plasmids showed activity, but the concurrent expression of both ORFs is needed for exclusion. Our data suggest that phage adsorption occurs but that phage genome translocation to the host’s cytoplasm is defective. To our knowledge, this is the first report on this type of exclusion mediated by a prophage in P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa is a Gram-negative bacterium frequently isolated from infected immunocompromised patients, and the strains are resistant to a broad spectrum of antibiotics. Recently, the use of phages has been proposed as an alternative therapy against multidrug-resistant bacteria. However, this approach may present various hurdles. This work addresses the problem that pathogenic bacteria may be lysogenized by phages carrying genes encoding resistance against secondary infections, such as those used in phage therapy. Discovering phage genes that exclude superinfecting phages not only assigns novel functions to orphan genes in databases but also provides insight into selection of the proper phages for use in phage therapy.

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