scholarly journals K2 Capsule Depolymerase Is Highly Stable, Is Refractory to Resistance, and Protects Larvae and Mice from Acinetobacter baumannii Sepsis

2019 ◽  
Vol 85 (17) ◽  
Author(s):  
Hugo Oliveira ◽  
Ana Mendes ◽  
Alexandra G. Fraga ◽  
Alice Ferreira ◽  
Andreia I. Pimenta ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Bacterial Infections ◽  
Multidrug Resistant ◽  
Host Immune System ◽  
Dependent Manner ◽  
Bacterial Cells ◽  
Capsular Type ◽  
Nosocomial Pathogen ◽  
Content Type

ABSTRACT Acinetobacter baumannii is emerging as a major nosocomial pathogen in intensive care units. The bacterial capsules are considered major virulence factors, and the particular A. baumannii capsular type K2 has been associated with high antibiotic resistance. In this study, we identified a K2 capsule-specific depolymerase in a bacteriophage tail spike C terminus, a fragment that was heterologously expressed, and its antivirulence properties were assessed by in vivo experiments. The K2 depolymerase is active under a broad range of environmental conditions and is highly thermostable, with a melting point (Tm) at 67°C. In the caterpillar larva model, the K2 depolymerase protects larvae from bacterial infections, using either pretreatments or with single-enzyme injection after bacterial challenge, in a dose-dependent manner. In a mouse sepsis model, a single K2 depolymerase intraperitoneal injection of 50 μg is able to protect 60% of mice from an otherwise deadly infection, with a significant reduction in the proinflammatory cytokine profile. We showed that the enzyme makes bacterial cells fully susceptible to the host complement system killing effect. Moreover, the K2 depolymerase is highly refractory to resistance development, which makes these bacteriophage-derived capsular depolymerases useful antivirulence agents against multidrug-resistant A. baumannii infections. IMPORTANCE Acinetobacter baumannii is an important nosocomial pathogen resistant to many, and sometimes all, antibiotics. The A. baumannii K2 capsular type has been associated with elevated antibiotic resistance. The capsular depolymerase characterized here fits the new trend of alternative antibacterial agents needed against multidrug-resistant pathogens. They are highly specific, stable, and refractory to resistance, as they do not kill bacteria per se; instead, they remove bacterial surface polysaccharides, which diminish the bacterial virulence and expose them to the host immune system.

scholarly journals Functional Characterization of AbaQ, a Novel Efflux Pump Mediating Quinolone Resistance inAcinetobacter baumannii

2018 ◽  
Vol 62 (9) ◽  
Author(s):  
María Pérez-Varela ◽  
Jordi Corral ◽  
Jesús Aranda ◽  
Jordi Barbé
Keyword(s):  
Acinetobacter Baumannii ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Functional Characterization ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Nosocomial Pathogen ◽  
Content Type ◽  
Mfs Transporter

ABSTRACTAcinetobacter baumanniihas emerged as an important multidrug-resistant nosocomial pathogen. In previous work, we identified a putative MFS transporter, AU097_RS17040, involved in the pathogenicity ofA. baumannii(M. Pérez-Varela, J. Corral, J. A. Vallejo, S. Rumbo-Feal, G. Bou, J. Aranda, and J. Barbé, Infect Immun 85:e00327-17, 2017,https://doi.org/10.1128/IAI.00327-17). In this study, we analyzed the susceptibility to diverse antimicrobial agents ofA. baumanniicells defective in this transporter, referred to as AbaQ. Our results showed that AbaQ is mainly involved in the extrusion of quinolone-type drugs inA. baumannii.

scholarly journals DNA Microarray for Genotyping Antibiotic Resistance Determinants in Acinetobacter baumannii Clinical Isolates

2013 ◽  
Vol 57 (10) ◽  
pp. 4761-4768 ◽  
Author(s):  
Simon Dally ◽  
Karin Lemuth ◽  
Martin Kaase ◽  
Steffen Rupp ◽  
Cornelius Knabbe ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Predictive Value ◽  
Handling Time ◽  
Multidrug Resistant ◽  
Testing System ◽  
Content Type ◽  
Resistance Determinants ◽  
Epidemiologic Surveillance ◽  
National Reference Center

ABSTRACTIn recent decades,Acinetobacter baumanniihas emerged as an organism of great concern due to its ability to accumulate antibiotic resistance. In order to improve the diagnosis of resistance determinants inA. baumanniiin terms of lead time and accuracy, we developed a microarray that can be used to detect 91 target sequences associated with antibiotic resistance within 4 h from bacterial culture to result. The array was validated with 60 multidrug-resistant strains ofA. baumanniiin a blinded, prospective study. The results were compared to phenotype results determined by the automated susceptibility testing system VITEK2. Antibiotics considered were piperacillin-tazobactam, ceftazidime, imipenem, meropenem, trimethoprim-sulfamethoxazole, amikacin, gentamicin, tobramycin, ciprofloxacin, and tigecycline. The average positive predictive value, negative predictive value, sensitivity, and specificity were 98, 98, 99, and 94%, respectively. For carbapenemase genes, the array results were compared to singleplex PCR results provided by the German National Reference Center for Gram-Negative Pathogens, and results were in complete concordance. The presented array is able to detect all relevant resistance determinants ofA. baumanniiin parallel. The short handling time of 4 h from culture to result helps to provide fast results in order to initiate adequate anti-infective therapy for critically ill patients. Another application would be data acquisition for epidemiologic surveillance.

scholarly journals Whole-Genome Sequences of Two Multidrug-Resistant Acinetobacter baumannii Strains Isolated from Patients with Urinary Tract Infection in Ghana

2019 ◽  
Vol 8 (31) ◽  
Author(s):  
Nicholas Agyepong ◽  
Usha Govinden ◽  
Alex Owusu-Ofori ◽  
Mushal Allam ◽  
Arshad Ismail ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Urinary Tract Infection ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Multiple Resistance ◽  
Whole Genome ◽  
Nosocomial Pathogen ◽  
Genome Sequences ◽  
Content Type ◽  
Multiple Resistance Genes

Multidrug-resistant Acinetobacter baumannii is a major nosocomial pathogen. We describe the whole-genome sequences of two multidrug-resistant Acinetobacter baumannii strains isolated from hospitalized patients in the intensive care unit at Komfo Anokye Teaching Hospital in Ghana. The isolates carry multiple resistance genes, including those for β-lactams, sulfonamides, aminoglycosides, and tetracycline.

scholarly journals Simple Method for Markerless Gene Deletion in Multidrug-Resistant Acinetobacter baumannii

2015 ◽  
Vol 81 (10) ◽  
pp. 3357-3368 ◽  
Author(s):  
Man Hwan Oh ◽  
Je Chul Lee ◽  
Jungmin Kim ◽  
Chul Hee Choi ◽  
Kyudong Han
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Gene Deletion ◽  
Multidrug Resistant ◽  
Simple Method ◽  
Content Type ◽  
Overlap Extension Pcr ◽  
Overlap Extension ◽  
Restriction Sites ◽  
Selection Of

ABSTRACTThe traditional markerless gene deletion technique based on overlap extension PCR has been used for generating gene deletions in multidrug-resistantAcinetobacter baumannii. However, the method is time-consuming because it requires restriction digestion of the PCR products in DNA cloning and the construction of new vectors containing a suitable antibiotic resistance cassette for the selection ofA. baumanniimerodiploids. Moreover, the availability of restriction sites and the selection of recombinant bacteria harboring the desired chimeric plasmid are limited, making the construction of a chimeric plasmid more difficult. We describe a rapid and easy cloning method for markerless gene deletion inA. baumannii, which has no limitation in the availability of restriction sites and allows for easy selection of the clones carrying the desired chimeric plasmid. Notably, it is not necessary to construct new vectors in our method. This method utilizes direct cloning of blunt-end DNA fragments, in which upstream and downstream regions of the target gene are fused with an antibiotic resistance cassette via overlap extension PCR and are inserted into a blunt-end suicide vector developed for blunt-end cloning. Importantly, the antibiotic resistance cassette is placed outside the downstream region in order to enable easy selection of the recombinants carrying the desired plasmid, to eliminate the antibiotic resistance cassette via homologous recombination, and to avoid the necessity of constructing new vectors. This strategy was successfully applied to functional analysis of the genes associated with iron acquisition byA. baumanniiATCC 19606 and toompAgene deletion in otherA. baumanniistrains. Consequently, the proposed method is invaluable for markerless gene deletion in multidrug-resistantA. baumannii.

scholarly journals Phage Therapy for a Multidrug-Resistant Acinetobacter baumannii Craniectomy Site Infection

2018 ◽  
Vol 5 (4) ◽  
Author(s):  
Stephanie LaVergne ◽  
Theron Hamilton ◽  
Biswajit Biswas ◽  
M Kumaraswamy ◽  
R T Schooley ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Alternative Treatment ◽  
Bacterial Infections ◽  
Phage Therapy ◽  
Treatment Options ◽  
Multidrug Resistant ◽  
Site Infection ◽  
Bacteriophage Therapy

Abstract In the era of antibiotic resistance, alternative treatment options for multidrug-resistant bacterial infections are being explored. We present a case of multidrug-resistant Acinetobacter baumannii infection treated with bacteriophages. Clinical trials are needed to further investigate bacteriophage therapy as an option to treat multidrug-resistant bacterial infections.

scholarly journals Genomic Analysis of the Multidrug-Resistant Acinetobacter baumannii Strain MDR-ZJ06 Widely Spread in China

2011 ◽  
Vol 55 (10) ◽  
pp. 4506-4512 ◽  
Author(s):  
Hua Zhou ◽  
Tongwu Zhang ◽  
Dongliang Yu ◽  
Borui Pi ◽  
Qing Yang ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Genomic Analysis ◽  
Multidrug Resistant ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Content Type ◽  
Resistance Island

ABSTRACTWe previously reported that the multidrug-resistant (MDR)Acinetobacter baumanniistrain MDR-ZJ06, belonging to European clone II, was widely spread in China. In this study, we report the whole-genome sequence of this clinically important strain. A 38.6-kb AbaR-type genomic resistance island (AbaR22) was identified in MDR-ZJ06. AbaR22 has a structure similar to those of the resistance islands found inA. baumanniistrains AYE and AB0057, but it contained only a few antibiotic resistance genes. The region of resistant gene accumulation as previously described was not found in AbaR22. In the chromosome of the strain MDR-ZJ06, we identified the geneblaoxa-23in a composite transposon (Tn2009). Tn2009shared the backbone with otherA. baumanniitransponsons that harborblaoxa-23, but it was bracketed by two ISAba1elements which were transcribed in the same orientation. MDR-ZJ06 also expressed thearmAgene on its plasmid pZJ06, and this gene has the same genetic environment as thearmAgene of theEnterobacteriaceae. These results suggest variability of resistance acquisition even in closely relatedA. baumanniistrains.

scholarly journals Conjugative Delivery of CRISPR-Cas9 for the Selective Depletion of Antibiotic-Resistant Enterococci

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Marinelle Rodrigues ◽  
Sara W. McBride ◽  
Karthik Hullahalli ◽  
Kelli L. Palmer ◽  
Breck A. Duerkop
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Infections ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Conjugative Plasmid ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Resistance Determinants

ABSTRACT The innovation of new therapies to combat multidrug-resistant (MDR) bacteria is being outpaced by the continued rise of MDR bacterial infections. Of particular concern are hospital-acquired infections (HAIs) that are recalcitrant to antibiotic therapies. The Gram-positive intestinal pathobiont Enterococcus faecalis is associated with HAIs, and some strains are MDR. Therefore, novel strategies to control E. faecalis populations are needed. We previously characterized an E. faecalis type II CRISPR-Cas system and demonstrated its utility in the sequence-specific removal of antibiotic resistance determinants. Here, we present work describing the adaption of this CRISPR-Cas system into a constitutively expressed module encoded on a pheromone-responsive conjugative plasmid that efficiently transfers to E. faecalis for the selective removal of antibiotic resistance genes. Using in vitro competition assays, we show that these CRISPR-Cas-encoding delivery plasmids, or CRISPR-Cas antimicrobials, can reduce the occurrence of antibiotic resistance in enterococcal populations in a sequence-specific manner. Furthermore, we demonstrate that deployment of CRISPR-Cas antimicrobials in the murine intestine reduces the occurrence of antibiotic-resistant E. faecalis by several orders of magnitude. Finally, we show that E. faecalis donor strains harboring CRISPR-Cas antimicrobials are immune to uptake of antibiotic resistance determinants in vivo. Our results demonstrate that conjugative delivery of CRISPR-Cas antimicrobials may be adaptable for future deployment from probiotic bacteria for exact targeting of defined MDR bacteria or for precision engineering of polymicrobial communities in the mammalian intestine.

scholarly journals Unravelling mechanisms of meropenem induced persistence facilitates identification of GRAS compounds with anti-persister activity against Acinetobacter baumannii

2020 ◽  
Author(s):  
Timsy Bhando ◽  
Ananth Casius ◽  
Siva R. Uppalapati ◽  
Ranjana Pathania
Keyword(s):  
Acinetobacter Baumannii ◽  
Bacterial Infections ◽  
Drug Tolerance ◽  
World Health Organisation ◽  
Screening Strategy ◽  
World Health ◽  
Bacterial Cells ◽  
Nosocomial Pathogen ◽  
Compound Libraries ◽  
Mechanisms Of Persistence

ABSTRACTAcinetobacter baumannii is recognized as one of the “critical” pathogens by the World Health Organisation (WHO) due to its unprecedented ability to acquire resistance genes and undergo genetic modifications. Carbapenem classes of antibiotics are considered as the “drugs of choice” against A. baumannii infections, although increasing incidence of carbapenem resistant isolates have greatly limited their efficacy in clinical settings. Nonetheless, the phenomenon of multi-drug tolerance or persistence exhibited by A. baumannii has further led to therapeutic failure of carbapenems against chronic and recurring infections. Exploring the underlying mechanisms of persistence hosted by the nosocomial pathogen, A. baumannii can facilitate the development of effective anti-persister strategies against them. Accordingly, this study investigates the characteristics and mechanisms responsible for meropenem induced persistence in A. baumannii. Furthermore, it describes the adaptation of a screening strategy for identification of potent anti-persister compounds that cumulatively act by targeting the A. baumannii membrane, inhibiting antibiotic efflux and inducing oxidative stress mediated killing. The screen identified the phytochemical compound, thymol to display excellent activity against persisters of mechanically distinct antibiotics. While meropenem exposed A. baumannii persisters exhibited multi-drug tolerance and indicated the ability to enter a Viable But Non Culturable (VBNC) state, thymol efficiently eradicated all persister cells, irrespective of their culturability. Thymol exhibited no propensity for resistance generation and also inhibited persisters of other Gram-negative pathogens, Pseudomonas aeruginosa and Klebsiella pneumoniae. Collectively, our results establish thymol to have immense potential to act either alone or as an adjunct in combination therapies against persistent infections.IMPORTANCEApart from the global catastrophe of antibiotic resistance, the phenomenon of “antibiotic tolerance” exhibited by a subpopulation of bacterial cells known as “persisters” ensue a major clinical threat. Eradication of the persister populations holds extreme importance for an improved long-term recovery from chronic and recurring bacterial infections. This study addresses the problem of antibiotic persistence prevailing in clinics and investigates its associated mechanisms in the nosocomial pathogen, Acinetobacter baumannii in reference to the antibiotic meropenem. It further describes the use of a mechanism-based screening approach for the identification of potent multi-targeting anti-persister compounds, thereby leading to the identification of GRAS (Generally Regarded As Safe) molecules exhibiting promising activity against A. baumannii persisters. This strategy can further be utilized for repurposing of FDA approved drugs or other available compound libraries, in order to identify novel anti-persister compounds.

scholarly journals Functional Analysis and Antivirulence Properties of a New Depolymerase from a Myovirus That Infects Acinetobacter baumannii Capsule K45

2018 ◽  
Vol 93 (4) ◽  
Author(s):  
Hugo Oliveira ◽  
Ana Rita Costa ◽  
Alice Ferreira ◽  
Nico Konstantinides ◽  
Sílvio B. Santos ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Therapeutic Potential ◽  
Host Immune System ◽  
Promising Alternative ◽  
Content Type ◽  
A Genome ◽  
Wide Range

ABSTRACT Acinetobacter baumannii is an important pathogen causative of health care-associated infections and is able to rapidly develop resistance to all known antibiotics, including colistin. As an alternative therapeutic agent, we have isolated a novel myovirus (vB_AbaM_B9) which specifically infects and makes lysis from without in strains of the K45 and K30 capsule types, respectively. Phage B9 has a genome of 93,641 bp and encodes 167 predicted proteins, of which 29 were identified by mass spectrometry. This phage holds a capsule depolymerase (B9gp69) able to digest extracted exopolysaccharides of both K30 and K45 strains and remains active in a wide range of pH values (5 to 9), ionic strengths (0 to 500 mM), and temperatures (20 to 80°C). B9gp69 was demonstrated to be nontoxic in a cell line model of the human lung and to make the K45 strain fully susceptible to serum killing in vitro. Contrary to the case with phage, no resistance development was observed by bacteria targeted with the B9gp69. Therefore, capsular depolymerases may represent attractive antimicrobial agents against A. baumannii infections. IMPORTANCE Currently, phage therapy has revived interest for controlling hard-to-treat bacterial infections. Acinetobacter baumannii is an emerging Gram-negative pathogen able to cause a variety of nosocomial infections. Additionally, this species is becoming more resistant to several classes of antibiotics. Here we describe the isolation of a novel lytic myophage B9 and its recombinant depolymerase. While the phage can be a promising alternative antibacterial agent, its success in the market will ultimately depend on new regulatory frameworks and general public acceptance. We therefore characterized the phage-encoded depolymerase, which is a natural enzyme that can be more easily managed and used. To our knowledge, the therapeutic potential of phage depolymerase against A. baumannii is still unknown. We show for the first time that the K45 capsule type is an important virulence factor of A. baumannii and that capsule removal via the recombinant depolymerase activity helps the host immune system to combat the bacterial infection.

scholarly journals Complete Genome Sequence of Collection Strain Acinetobacter baumannii ATCC BAA-1790, Used as a Model To Study the Antibiotic Resistance Reversion Induced by Iodine-Containing Complexes

2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Ilya S. Korotetskiy ◽  
Monique Joubert ◽  
Sade M. Magabotha ◽  
Ardak B. Jumagaziyeva ◽  
Sergey V. Shilov ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Genomic Islands ◽  
Circular Chromosome ◽  
Content Type ◽  
Genome Methylation ◽  
Long Read ◽  
Collection Strain

The strain Acinetobacter baumannii ATCC BAA-1790 was sequenced as a model for nosocomial multidrug-resistant infections. Long-read PacBio sequencing revealed a circular chromosome of 3,963,235 bp with two horizontally transferred genomic islands and a 67,023-bp plasmid. Multiple antibiotic resistance genes and genome methylation patterns were identified.

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