Detection and characterization of quorum sensing signal molecules in Acinetobacter strains

Gonzalez, Rodrigo; Nusblat, Alejandro D.; Nudel, B.C.

doi:10.1016/s0944-5013(01)80004-5

Cited by 60 publications

(44 citation statements)

References 22 publications

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“…Finally, quorum sensing has been shown to regulate a wide array of virulence mechanisms in many gram-negative organisms, particularly P. aeruginosa. Up to four different quorum-sensing signal molecules have been identified in Acinetobacter, indicating that this may be a central mechanism for autoinduction of multiple virulence factors (203,271).…”

Section: Host-pathogen Interactions Involving Acinetobactermentioning

confidence: 99%

Acinetobacter baumannii : Emergence of a Successful Pathogen

2008

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SUMMARY Acinetobacter baumannii has emerged as a highly troublesome pathogen for many institutions globally. As a consequence of its immense ability to acquire or upregulate antibiotic drug resistance determinants, it has justifiably been propelled to the forefront of scientific attention. Apart from its predilection for the seriously ill within intensive care units, A. baumannii has more recently caused a range of infectious syndromes in military personnel injured in the Iraq and Afghanistan conflicts. This review details the significant advances that have been made in our understanding of this remarkable organism over the last 10 years, including current taxonomy and species identification, issues with susceptibility testing, mechanisms of antibiotic resistance, global epidemiology, clinical impact of infection, host-pathogen interactions, and infection control and therapeutic considerations.

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Section: Host-pathogen Interactions Involving Acinetobactermentioning

confidence: 99%

Acinetobacter baumannii : Emergence of a Successful Pathogen

2008

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“…18 In A. baumannii, N-(3-hydroxydodecanoyl)-l-homoserine lactone (3-hydroxy-C12-HSL) is the only quorum sensing molecule identified, though mass spectrometry suggested that other AHL molecules are also present at significantly lower amounts. [19][20][21] However,contribution of quorum sensors and iron concentration to the overall pathogenic potential in the genus is currently unknown.…”

Section: Introductionmentioning

confidence: 99%

Iron limitation enhances acyl homoserine lactone (AHL) production and biofilm formation in clinical isolates ofAcinetobacter baumannii

Modaresi¹,

Azizi

Shakibaie³

et al. 2015

Virulence

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Acinetobacter baumannii is an important source of infections in intensive care units (ICUs) of our hospitals in Kerman, Iran and the most frequently isolated strains produce biofilm. There is a little information about role of iron (Fe) levels on acyl homoserine lactone (AHL) production and biofilm formation in this microorganism. In the present study, we investigated the influence of iron-III limitation on AHL, siderophore, catechol and virulence factors in the biofilm forming clinical strains of A. baumannii. A total of 65 non-duplicated multidrug resistance (MDR) strains of A. baumannii were isolated from patients in ICUs of 2 hospitals in Kerman, Iran. Antibiotic susceptibility, siderophore and other iron chelators, hemolysis, cell twitching motility, capsule, gelatinase and DNase were studied. Presence of quorum sensing, LuxI and LuxR genes was detected by multiplex-PCR. AHL activity quantified by colorimetric method and the functional groups were determined by Fourier Transform Infra-Red Spectroscopy (FT-IR). Biofilm formation was detected by microtiter plate technique. All of the isolates were resistant to third generation of cephalosporins, ciprofloxacin, levofloxacin, tetracycline, whereas, 78% and 81% were resistant to amikacin and carbapenems, respectively. The siderophore activity was highest at 20 mM Fe 3C (70%); however, it decreased to 45% as concentration of Fe 3C increased to 80 mM. Furthermore, screening of the isolates for LuxI and LuxR genes showed that presence of both genes required in the isolates with high AHL activity. FT-IR analysis indicated CDO bond of the lactone ring and primary amides. Significantly, a higher amount of AHL (70%) was detected in the presence of low concentration of iron-III (20 mM); as iron concentration increased to 80 mM, the AHL activity was reduced to 40% (P 0.05). All the isolates exhibited twitching motility and had a capsule. No any gelatinase or DNase activity was detected. Quantification of the biofilm formation introduced 23 isolates with efficient attachment to microplate wells and strong biofilm. We found that both the AHL production and biofilm formation were regulated by iron concentration in a dose dependent manner. These findings provide evidence that iron limitation plays an important regulatory role in AHL and siderophore production resulting in strong or weak biofilm, thereby helping the organism to persist in less available micronutrient environment.

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“…Using these biosensors, previous studies showed AHL production by Acinetobacter spp. (15). In a variety of gram-negative bacteria, it has also been demonstrated that biofilm development can be dependent on AHL signaling (7,18,26).…”

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confidence: 99%

Isolation and Characterization of an Autoinducer Synthase from Acinetobacter baumannii

et al. 2008

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The opportunistic human pathogen Acinetobacter baumannii strain M2 was found to produce distinct acyl-homoserine lactone (AHL) signals based on the use of an Agrobacterium tumefaciens traG-lacZ biosensor. An A. baumannii gene, designated abaI, was cloned and directed AHL production in recombinant Escherichia coli. The AbaI protein was similar to members of the LuxI family of autoinducer synthases and was predicted to be the only autoinducer synthase encoded by A. baumannii. The primary AHL signal directed by AbaI was identified by mass spectrometry as being N-(3-hydroxydodecanoyl)-L-HSL (3-hydroxy-C 12 -HSL). Minor amounts of at least five additional AHLs were also identified. The expression of abaI at the transcriptional level was activated by ethyl acetate extracts of culture supernatants or by synthetic 3-hydroxy-C 12 -HSL. An abaI::Km mutant failed to produce any detectable AHL signals and was impaired in biofilm development.

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Detection and characterization of quorum sensing signal molecules in Acinetobacter strains

Cited by 60 publications

References 22 publications

Acinetobacter baumannii : Emergence of a Successful Pathogen

Acinetobacter baumannii : Emergence of a Successful Pathogen

Iron limitation enhances acyl homoserine lactone (AHL) production and biofilm formation in clinical isolates ofAcinetobacter baumannii

Isolation and Characterization of an Autoinducer Synthase from Acinetobacter baumannii

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