Virulence characteristics of multidrug resistant biofilm forming  Acinetobacter baumannii  isolated from intensive care unit patients

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Abstract

Background

Nosocomial infections and persistence of multidrug resistant biofilm forming Acinetobacter baumannii in hospitals has made it as a serious problem in healthcare settings worldwide.

Methods

A total of 100 A. baumannii clinical isolates from immunocompromised patients hospitalized in ICU were investigated for biofilm formation, the presence of biofilm related genes ( bap, ompA, csuE, fimH, epsA, bla _PER-1 , bfmS, ptk, pgaB, csgA, kpsMII), integron characterization and molecular typing based on REP-PCR.

Results

All isolates were resistant to three or more categories of antibiotics and considered as multidrug resistant (MDR). A total of 32 isolates were resistant to all tested antibiotics and 91% were extensively drug-resistance (XDR). All isolates were able to produce biofilm and 58% of isolates showed strong ability to biofilm formation. All strong biofilm forming A. baumannii isolates were XDR. All A. baumannii isolates carried at least one biofilm related gene. The most prevalent gene was csuE (100%), followed by pgaB (98%), epsA and ptk (95%), bfmS (92%) and ompA (81%). 98% of isolates carried more than 4 biofilm related genes, simultaneously. Class I integron (67%) was more frequent in comparison with class II (10%) ( P < 0.05). The REP-PCR patterns were classified as 8 types (A-H) and 21 subtypes. The A1 (23%) and C1 (15%) clusters were the most prevalent among A. baumannii isolates ( P < 0.05). According to the REP-PCR patterns, 23% of all isolates had a clonal relatedness.

Conclusion

Our study revealed the high frequency of biofilm forming XDR A. baumannii in ICU patients, with a high prevalence of biofilm related genes of csuE and pgaB. It seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of XDR A. baumannii in our country.

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Most cited references 22

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Relationship between Antibiotic Resistance, Biofilm Formation, and Biofilm-Specific Resistance in Acinetobacter baumannii

Lihua Qi, Hao Li, CHUANFU ZHANG … (2016)

In this study, we aimed to examine the relationships between antibiotic resistance, biofilm formation, and biofilm-specific resistance in clinical isolates of Acinetobacter baumannii. The tested 272 isolates were collected from several hospitals in China during 2010–2013. Biofilm-forming capacities were evaluated using the crystal violet staining method. Antibiotic resistance/susceptibility profiles to 21 antibiotics were assessed using VITEK 2 system, broth microdilution method or the Kirby-Bauer disc diffusion method. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) to cefotaxime, imipenem, and ciprofloxacin were evaluated using micro dilution assays. Genetic relatedness of the isolates was also analyzed by pulsed-field gel electrophoresis (PFGE) and plasmid profile. Among all the 272 isolates, 31 were multidrug-resistant (MDR), and 166 were extensively drug-resistant (XDR). PFGE typing revealed 167 pattern types and 103 clusters with a similarity of 80%. MDR and XDR isolates built up the main prevalent genotypes. Most of the non-MDR isolates were distributed in a scattered pattern. Additionally, 249 isolates exhibited biofilm formation, among which 63 were stronger biofilm formers than type strain ATCC19606. Population that exhibited more robust biofilm formation likely contained larger proportion of non-MDR isolates. Isolates with higher level of resistance tended to form weaker biofilms. The MBECs for cefotaxime, imipenem, and ciprofloxacin showed a positive correlation with corresponding MICs, while the enhancement in resistance occurred independent of the quantity of biofilm biomass produced. Results from this study imply that biofilm acts as a mechanism for bacteria to get a better survival, especially in isolates with resistance level not high enough. Moreover, even though biofilms formed by isolates with high level of resistance are always weak, they could still provide similar level of protection for the isolates. Further explorations genetically would improve our understanding of these processes and provide novel insights in the therapeutics and prevention against A. baumannii biofilm-related infections.

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The enterococcal surface protein, Esp, is involved in Enterococcus faecalis biofilm formation.

B Amorena, D C Solano, C Cucarella … (2001)

The enterococcal surface protein, Esp, is a high-molecular-weight surface protein of unknown function whose frequency is significantly increased among infection-derived Enterococcus faecalis isolates. In this work, a global structural similarity was found between Bap, a biofilm-associated protein of Staphylococcus aureus, and Esp. Analysis of the relationship between the presence of the Esp-encoding gene (esp) and the biofilm formation capacity in E. faecalis demonstrated that the presence of the esp gene is highly associated (P < 0.0001) with the capacity of E. faecalis to form a biofilm on a polystyrene surface, since 93.5% of the E. faecalis esp-positive isolates were capable of forming a biofilm. Moreover, none of the E. faecalis esp-deficient isolates were biofilm producers. Depending on the E. faecalis isolate, insertional mutagenesis of esp caused either a complete loss of the biofilm formation phenotype or no apparent phenotypic defect. Complementation studies revealed that Esp expression in an E. faecalis esp-deficient strain promoted primary attachment and biofilm formation on polystyrene and polyvinyl chloride plastic from urine collection bags. Together, these results demonstrate that (i) biofilm formation capacity is widespread among clinical E. faecalis isolates, (ii) the biofilm formation capacity is restricted to the E. faecalis strains harboring esp, and (iii) Esp promotes primary attachment and biofilm formation of E. faecalis on abiotic surfaces.

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Capacity of multidrug-resistant clinical isolates of Acinetobacter baumannii to form biofilm and adhere to epithelial cell surfaces.

H Y Seol, D Cho, T. J. Kim … (2007)

This study evaluated the capacity of 23 multidrug-resistant (MDR) clinical isolates of Acinetobacter baumannii to adhere to respiratory epithelial cell surfaces and to form biofilm on a polystyrene surface. All 23 A. baumannii isolates were capable of adhering efficiently to respiratory epithelial cells, and biofilm production was positively associated with epithelial cell adhesiveness (r 0.80, p <0.0001). In the presence of the chelating agent EDTA, biofilm formation was markedly reduced. Cell adhesiveness and biofilm formation were significantly higher in isolates carrying the bla(PER-1) gene as compared with isolates without this extended-spectrum beta-lactamase gene (p <0.005 and p <0.001, respectively). Further examination by RT-PCR showed a positive correlation between the level of expression of the bla(PER-1) gene and the level of biofilm formation (r 0.89, p <0.0001) and cell adhesiveness (r 0.74, p <0.006). Overall, the study demonstrated a high capacity of clinical isolates of MDR A. baumannii to form biofilm and to adhere to respiratory epithelial cells. This feature, combined with multidrug resistance, might contribute to the survival of these organisms and their dissemination in the hospital environment.

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Author and article information

Contributors

Fakhri Haghi: +982433140296 , haghi@zums.ac.ir

Journal

Journal ID (nlm-ta): BMC Infect Dis

Journal ID (iso-abbrev): BMC Infect. Dis

Title: BMC Infectious Diseases

Publisher: BioMed Central (London )

ISSN (Electronic): 1471-2334

Publication date (Electronic): 17 July 2019

Publication date PMC-release: 17 July 2019

Publication date Collection: 2019

Volume: 19

Electronic Location Identifier: 629

Affiliations

[1 ]ISNI 0000 0004 0612 8427, GRID grid.469309.1, Department of Microbiology, School of Medicine, , Zanjan University of Medical Sciences, ; Zanjan, Iran

[2 ]Department of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran

Article

Publisher ID: 4272

DOI: 10.1186/s12879-019-4272-0

PMC ID: 6637494

PubMed ID: 31315572

SO-VID: a3587905-d566-4314-bb5d-9ab84b5ab164

License:

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.