DNA Uptake by the Nosocomial Pathogen Acinetobacter baumannii Occurs during Movement along Wet Surfaces

Wilharm, Gottfried; Piesker, Janett; Laue, Michael; Skiebe, Evelyn

doi:10.1128/jb.00754-13

Cited by 114 publications

(172 citation statements)

References 55 publications

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“…Although bioinformatic studies have identified genes predicted to encode proteins required for the biogenesis of Tfp in A. baumannii, only Acinetobacter nosocomialis strain M2 has been shown conclusively to produce functioning Tfp (66,67), which is glycosylated by a TfpO-like oligosaccharyltransferase (30). Many A. baumannii isolates have been found to be naturally transformable and to exhibit twitching motility (63,(68)(69)(70), two classic Tfp-associated phenotypes, which strongly indicates their presence. Tfp-like structures were also identified on A. baumannii ATCC 17978 (71); furthermore, mutants in predicted Tfp biogenesis components of A. baumannii ATCC 17978 exhibited impaired biofilm formation (71) but the major pilin subunit, PilA, has not been shown to be surface exposed and/or associated with the pilin structures observed.…”

Section: Cell Surfacementioning

confidence: 99%

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

2016

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The genus Acinetobacter encompasses multiple nosocomial opportunistic pathogens that are of increasing worldwide relevance because of their ability to survive exposure to various antimicrobial and sterilization agents. Among these, Acinetobacter baumannii, Acinetobacter nosocomialis, and Acinetobacter pittii are the most frequently isolated in hospitals around the world. Despite the growing incidence of multidrug-resistant Acinetobacter spp., little is known about the factors that contribute to pathogenesis. New strategies for treating and managing infections caused by multidrug-resistant Acinetobacter strains are urgently needed, and this requires a detailed understanding of the pathobiology of these organisms. In recent years, some virulence factors important for Acinetobacter colonization have started to emerge. In this review, we focus on several recently described virulence factors that act at the bacterial surface level, such as the capsule, O-linked protein glycosylation, and adhesins. Furthermore, we describe the current knowledge regarding the type II and type VI secretion systems present in these strains.

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Section: Cell Surfacementioning

confidence: 99%

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

2016

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“…Uptake of free DNA from the medium also is unlikely, although some A. baumannii strains previously were shown to be capable of natural transformation. A. baumannii CIP 70.10 encodes a type IV pilus (T4P) system and a channel formed by the proteins ComA/ComEC implicated in DNA uptake from outside the cell (48). However, transformation efficiency was shown to be very low for strain CIP 70.10 (49).…”

Section: Figmentioning

confidence: 99%

Intraspecies Transfer of the Chromosomal Acinetobacter baumannii bla _NDM-1 Carbapenemase Gene

Krahn

Wibberg

Maus

et al. 2016

Antimicrob Agents Chemother

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The species Acinetobacter baumannii is one of the most important multidrug-resistant human pathogens. To determine its virulence and antibiotic resistance determinants, the genome of the nosocomial bla NDM-1 -positive A. baumannii strain R2090 originating from Egypt was completely sequenced. Genome analysis revealed that strain R2090 is highly related to the communityacquired Australian A. baumannii strain D1279779. The two strains belong to sequence type 267 (ST267). Isolate R2090 harbored the chromosomally integrated transposon Tn125 carrying the carbapenemase gene bla NDM-1 that is not present in the D1279779 genome. To test the transferability of the metallo-␤-lactamase (MBL) gene region, the clinical isolate R2090 was mated with the susceptible A. baumannii recipient CIP 70.10, and the carbapenem-resistant derivative R2091 was obtained. Genome sequencing of the R2091 derivative revealed that it had received an approximately 66-kb region comprising the transposon Tn125 embedding the bla NDM-1 gene. This region had integrated into the chromosome of the recipient strain CIP 70.10. From the four known mechanisms for horizontal gene transfer (conjugation, outer membrane vesicle-mediated transfer, transformation, and transduction), conjugation could be ruled out, since strain R2090 lacks any plasmid, and a type IV secretion system is not encoded in its chromosome. However, strain R2090 possesses three putative prophages, two of which were predicted to be complete and therefore functional. Accordingly, it was supposed that the transfer of the resistance gene region from the clinical isolate R2090 to the recipient occurred by general transduction facilitated by one of the prophages present in the R2090 genome. Hence, phage-mediated transduction has to be taken into account for the dissemination of antibiotic resistance genes within the species A. baumannii.

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“…For Acinetobacter spp., most of the studies focusing on this issue were performed by using Acinetobacter baylyi strain ADP1 (16)(17)(18)(19)(20), a bacterium not as threatening to human health as A. baumannii (18)(19)(20)(21)(22)(23). Data regarding A. baumannii and competence inducers are scarce (24)(25)(26)(27). Wilharm et al showed previously that several A. baumannii clinical isolates were able to acquire exogenous DNA depending on the expression of pilT, encoding an ATPase involved in type IV pilus retraction, and comEC, encoding the DNA uptake channel (26).…”

mentioning

confidence: 99%

“…Data regarding A. baumannii and competence inducers are scarce (24)(25)(26)(27). Wilharm et al showed previously that several A. baumannii clinical isolates were able to acquire exogenous DNA depending on the expression of pilT, encoding an ATPase involved in type IV pilus retraction, and comEC, encoding the DNA uptake channel (26). Another study showed that the natural competence of Acinetobacter nosocomialis strain M2 relies on the presence of pilA, pilD, and pilT (28).…”

mentioning

confidence: 99%

Serum Albumin and Ca ²⁺ Are Natural Competence Inducers in the Human Pathogen Acinetobacter baumannii

Traglia

Quinn

Schramm

et al. 2016

Antimicrob Agents Chemother

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The increasing frequency of bacteria showing antimicrobial resistance (AMR) raises the menace of entering into a postantibiotic era. Horizontal gene transfer (HGT) is one of the prime reasons for AMR acquisition. Acinetobacter baumannii is a nosocomial pathogen with outstanding abilities to survive in the hospital environment and to acquire resistance determinants. Its capacity to incorporate exogenous DNA is a major source of AMR genes; however, few studies have addressed this subject. The transformation machinery as well as the factors that induce natural competence in A. baumannii are unknown. In this study, we demonstrate that naturally competent strain A118 increases its natural transformation frequency upon the addition of Ca 2؉ or albumin. We show that comEA and pilQ are involved in this process since their expression levels are increased upon the addition of these compounds. An unspecific protein, like casein, does not reproduce this effect, showing that albumin's effect is specific. Our work describes the first specific inducers of natural competence in A. baumannii. Overall, our results suggest that the main protein in blood enhances HGT in A. baumannii, contributing to the increase of AMR in this threatening human pathogen.A cinetobacter baumannii has emerged as a severe nosocomial pathogen over the course of the last few decades, with high levels of morbidity and mortality associated with infections by this pathogen (1, 2). A. baumannii is considered to be a paradigm of multidrug resistance since it has developed resistance to almost all available antibiotics, leaving few or no treatment options left. The ability of A. baumannii to persist in the clinical setting even under desiccation and nutrient starvation, as well as its ability to accumulate several antibiotic resistance determinants, allowed its evolution as a successful pathogen in the hospital environment (3).The large number of available A. baumannii genomes (n ϭ 1,289) shows that foreign DNA is acquired at high frequencies (4-7).The transformation process has been well described for some species, such as Streptococcus pneumoniae, Vibrio cholerae, Neisseria meningitidis, and Helicobacter pylori (8-12). However, how natural competence is regulated has not been thoroughly studied, particularly for Gram-negative bacteria. Some well-characterized competence inducers are DNA damage in H. pylori (13), starvation, as was suggested for Haemophilus influenzae, and chitin metabolism in Vibrio cholerae (14,15). In most known examples, natural competence is a transitory state that is regulated by different internal and external signals. Often, these regulation networks are not completely understood. For Acinetobacter spp., most of the studies focusing on this issue were performed by using Acinetobacter baylyi strain ADP1 (16-20), a bacterium not as threatening to human health as A. baumannii (18-23). Data regarding A. baumannii and competence inducers are scarce (24-27). Wilharm et al. showed previously that several A. baumannii clinical isolates were a...

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DNA Uptake by the Nosocomial Pathogen Acinetobacter baumannii Occurs during Movement along Wet Surfaces

Cited by 114 publications

References 55 publications

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

Intraspecies Transfer of the Chromosomal Acinetobacter baumannii bla _NDM-1 Carbapenemase Gene

Serum Albumin and Ca ²⁺ Are Natural Competence Inducers in the Human Pathogen Acinetobacter baumannii

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DNA Uptake by the Nosocomial Pathogen Acinetobacter baumannii Occurs during Movement along Wet Surfaces

Cited by 114 publications

References 55 publications

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond

Intraspecies Transfer of the Chromosomal Acinetobacter baumannii bla NDM-1 Carbapenemase Gene

Serum Albumin and Ca 2+ Are Natural Competence Inducers in the Human Pathogen Acinetobacter baumannii

Contact Info

Product

Resources

About

Intraspecies Transfer of the Chromosomal Acinetobacter baumannii bla _NDM-1 Carbapenemase Gene

Serum Albumin and Ca ²⁺ Are Natural Competence Inducers in the Human Pathogen Acinetobacter baumannii