scholarly journals Imipenem Treatment Induces Expression of Important Genes and Phenotypes in a Resistant Acinetobacter baumannii Isolate

2015 ◽  
Vol 60 (3) ◽  
pp. 1370-1376 ◽  
Author(s):  
Ghulam Nasser Dhabaan ◽  
Sazaly AbuBakar ◽  
Gustavo Maia Cerqueira ◽  
Mohammed Al-Haroni ◽  
Sui Ping Pang ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Clinical Success ◽  
Multidrug Resistant ◽  
Type Iv Pili ◽  
Control Measures ◽  
Content Type ◽  
Type Iv ◽  
Abiotic Surfaces ◽  
Colonization Factors

Acinetobacter baumanniihas emerged as a notorious multidrug-resistant pathogen, and development of novel control measures is of the utmost importance. Understanding the factors that play a role in drug resistance may contribute to the identification of novel therapeutic targets. Pili are essential forA. baumanniiadherence to and biofilm formation on abiotic surfaces as well as virulence. In the present study, we found that biofilm formation was significantly induced in an imipenem-resistant (Impr) strain treated with a subinhibitory concentration of antibiotic compared to that in an untreated control and an imipenem-susceptible (Imps) isolate. Using microarray and quantitative PCR analyses, we observed that several genes responsible for the synthesis of type IV pili were significantly upregulated in the Imprbut not in the Impsisolate. Notably, this finding is corroborated by an increase in the motility of the Imprstrain. Our results suggest that the ability to overproduce colonization factors in response to imipenem treatment confers biological advantage toA. baumanniiand may contribute to clinical success.

scholarly journals Microbicides Alter the Expression and Function of RND-Type Efflux Pump AdeABC in Biofilm-Associated Cells of Acinetobacter baumannii Clinical Isolates

2015 ◽  
Vol 60 (1) ◽  
pp. 57-63 ◽  
Author(s):  
Suvarna Krishnamoorthy ◽  
Bhavikkumar P. Shah ◽  
Hiu Ham Lee ◽  
Luis R. Martinez
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Efflux Pump ◽  
Acquired Resistance ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Content Type ◽  
Abiotic Surfaces ◽  
Hospital Environments ◽  
And Function

ABSTRACTAcinetobacter baumanniiis a Gram-negative bacterium that causes nosocomial infections worldwide. This microbe's propensity to form biofilms allows it to persist and to survive on clinical abiotic surfaces for long periods. In fact,A. baumanniibiofilm formation and its multidrug-resistant nature severely compromise our capacity to care for patients in hospital environments. In contrast, microbicides such as cetrimide (CT) and chlorhexidine (CHX) play important roles in the prevention and treatment of infections. We assessed the efficacy of CT and CHX, either alone or in combination, in eradicatingA. baumanniibiofilms formed by clinical isolates, by using stainless steel washers to mimic hard abiotic surfaces found in hospital settings. We demonstrated that increasing amounts of each microbicide, alone or in combination, were able to damage and to reduce the viability ofA. baumanniibiofilms efficaciously. Interestingly, theadeBgene of the resistance-nodulation-cell division (RND) family is predominantly associated with acquired resistance to antimicrobials inA. baumannii. We showed that CT and CHX adversely modified the expression and function of the RND-type efflux pump AdeABC in biofilm-associatedA. baumanniicells. Furthermore, we established that these microbicides decreased the negative charges onA. baumanniicell membranes, causing dysregulation of the efflux pump and leading to cell death. Our findings suggest that CT and CHX, alone or in combination, can be used efficaciously for eradication ofA. baumanniifrom hospital surfaces, in order to reduce infections caused by this nosocomial agent.

scholarly journals Biofilm-Formation in Clonally Unrelated Multidrug-Resistant Acinetobacter baumannii Isolates

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 630 ◽  
Author(s):  
Aisha M. Alamri ◽  
Afnan A. Alsultan ◽  
Mohammad A. Ansari ◽  
Amani M. Alnimr
Keyword(s):  
Tissue Culture ◽  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Congo Red ◽  
Biofilm Formation ◽  
Multidrug Resistant ◽  
Control Measures ◽  
Infection Control Measures ◽  
Culture Plate ◽  
Tissue Culture Plate

This study analyzed the genotype, antibiotic resistance, and biofilm formation of Acinetobacter baumannii strains and assessed the correlation between biofilm formation, antibiotic resistance, and biofilm-related risk factors. A total of 207 non-replicate multi-drug-resistant A. baumannii strains were prospectively isolated. Phenotypic identification and antimicrobial susceptibility testing were carried out. Isolate biofilm formation ability was evaluated using the tissue culture plate (TCP), Congo red agar, and tube methods. Clonal relatedness between the strains was assessed by enterobacterial repetitive intergenic consensus-PCR genotyping. Of the 207 isolates, 52.5% originated from an intensive care unit setting, and pan resistance was observed against ceftazidime and cefepime, with elevated resistance (99–94%) to piperacillin/tazobactam, imipenem, levofloxacin, and ciprofloxacin. alongside high susceptibility to tigecycline (97.8%). The Tissue culture plate, Tube method, and Congo red agar methods revealed that 53.6%, 20.8%, and 2.7% of the strains were strong biofilm producers, respectively, while a significant correlation was observed between biofilm formation and device-originating respiratory isolates (p = 0.0009) and between biofilm formation in colonized vs. true infection isolates (p = 0.0001). No correlation was detected between antibiotic resistance and biofilm formation capacity, and the majority of isolates were clonally unrelated. These findings highlight the urgent need for implementing strict infection control measures in clinical settings.

scholarly journals Molecular Analysis of the Acinetobacter baumannii Biofilm-Associated Protein

2013 ◽  
Vol 79 (21) ◽  
pp. 6535-6543 ◽  
Author(s):  
H. M. Sharon Goh ◽  
Scott A. Beatson ◽  
Makrina Totsika ◽  
Danilo G. Moriel ◽  
Minh-Duy Phan ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Multidrug Resistant ◽  
Hospital Environment ◽  
Biofilm Growth ◽  
Content Type ◽  
Amino Acid Region ◽  
Carbapenem Resistant ◽  
C Terminus ◽  
And Function

ABSTRACTAcinetobacter baumanniiis a multidrug-resistant pathogen associated with hospital outbreaks of infection across the globe, particularly in the intensive care unit. The ability ofA. baumanniito survive in the hospital environment for long periods is linked to antibiotic resistance and its capacity to form biofilms. Here we studied the prevalence, expression, and function of theA. baumanniibiofilm-associated protein (Bap) in 24 carbapenem-resistantA. baumanniiST92 strains isolated from a single institution over a 10-year period. Thebapgene was highly prevalent, with 22/24 strains being positive forbapby PCR. Partial sequencing ofbapwas performed on the index case strain MS1968 and revealed it to be a large and highly repetitive gene approximately 16 kb in size. Phylogenetic analysis employing a 1,948-amino-acid region corresponding to the C terminus of Bap showed that BapMS1968clusters with Bap sequences from clonal complex 2 (CC2) strains ACICU, TCDC-AB0715, and 1656-2 and is distinct from Bap in CC1 strains. By using overlapping PCR, thebapMS1968gene was cloned, and its expression in a recombinantEscherichia colistrain resulted in increased biofilm formation. A Bap-specific antibody was generated, and Western blot analysis showed that the majority ofA. baumanniistrains expressed an ∼200-kDa Bap protein. Further analysis of three Bap-positiveA. baumanniistrains demonstrated that Bap is expressed at the cell surface and is associated with biofilm formation. Finally, biofilm formation by these Bap-positive strains could be inhibited by affinity-purified Bap antibodies, demonstrating the direct contribution of Bap to biofilm growth byA. baumanniiclinical isolates.

scholarly journals Synergistic Effects and Antibiofilm Properties of Chimeric Peptides against Multidrug-Resistant Acinetobacter baumannii Strains

2013 ◽  
Vol 58 (3) ◽  
pp. 1622-1629 ◽  
Author(s):  
Ramamourthy Gopal ◽  
Young Gwon Kim ◽  
Jun Ho Lee ◽  
Seog Ki Lee ◽  
Jeong Don Chae ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Synergistic Effects ◽  
Antibacterial Activities ◽  
Multidrug Resistant ◽  
Drug Resistant ◽  
Antibacterial Effects ◽  
Content Type ◽  
Chimeric Peptides ◽  
Novel Antibiotics

ABSTRACTThe increasing prevalence of drug-resistant pathogens highlights the need to identify novel antibiotics. Here we investigated the efficacies of four new antimicrobial peptides (AMPs) for potential drug development. The antibacterial activities, synergistic effects, and antibiofilm properties of the four chimeric AMPs were tested againstAcinetobacter baumannii, an emerging Gram-negative, nosocomial, drug-resistant pathogen. NineteenA. baumanniistrains resistant to ampicillin, cefotaxime, ciprofloxacin, tobramycin, and erythromycin were isolated at a hospital from patients with cholelithiasis. All four peptides exhibited significant antibacterial effects (MIC = 3.12 to 12.5 μM) against all 19 strains, whereas five commercial antibiotics showed little or no activity against the same pathogens. An exception was polymyxin, which was effective against all of the strains tested. Each of the peptides showed synergy against one or more strains when administered in combination with cefotaxime, ciprofloxacin, or erythromycin. The peptides also exhibited an ability to prevent biofilm formation, which was not seen with cefotaxime, ciprofloxacin, or erythromycin, though polymyxin also inhibited biofilm formation. Indeed, when administered in combination with ciprofloxacin, the AMP HPMA exerted a potent synergistic effect againstA. baumanniibiofilm formation. Collectively, our findings indicate that the AMPs tested have no cytotoxicity but possess potent antibacterial and antibiofilm activities and may act synergistically with commercial antibiotics.

scholarly journals Regulation of Type IV Pili Contributes to Surface Behaviors of Historical and Epidemic Strains of Clostridium difficile

2015 ◽  
Vol 198 (3) ◽  
pp. 565-577 ◽  
Author(s):  
Erin B. Purcell ◽  
Robert W. McKee ◽  
Eric Bordeleau ◽  
Vincent Burrus ◽  
Rita Tamayo
Keyword(s):  
Clostridium Difficile ◽  
Biofilm Formation ◽  
The United States ◽  
Type Iv Pili ◽  
Flagellar Motility ◽  
Content Type ◽  
Type Iv ◽  
Intestinal Pathogen ◽  
Surface Motility ◽  
Pilin Gene

ABSTRACTThe intestinal pathogenClostridium difficileis an urgent public health threat that causes antibiotic-associated diarrhea and is a leading cause of fatal nosocomial infections in the United States.C. difficilerates of recurrence and mortality have increased in recent years due to the emergence of so-called “hypervirulent” epidemic strains. A great deal of the basic biology ofC. difficilehas not been characterized. Recent findings that flagellar motility, toxin synthesis, and type IV pilus (TFP) formation are regulated by cyclic diguanylate (c-di-GMP) reveal the importance of this second messenger forC. difficilegene regulation. However, the function(s) of TFP inC. difficileremains largely unknown. Here, we examine TFP-dependent phenotypes and the role of c-di-GMP in controlling TFP production in the historical 630 and epidemic R20291 strains ofC. difficile. We demonstrate that TFP contribute toC. difficilebiofilm formation in both strains, but with a more prominent role in R20291. Moreover, we report that R20291 is capable of TFP-dependent surface motility, which has not previously been described inC. difficile. The expression and regulation of thepilA1pilin gene differs between R20291 and 630, which may underlie the observed differences in TFP-mediated phenotypes. The differences inpilA1expression are attributable to greater promoter-driven transcription in R20291. In addition, R20291, but not 630, upregulates c-di-GMP levels during surface-associated growth, suggesting that the bacterium senses its substratum. The differential regulation of surface behaviors in historical and epidemicC. difficilestrains may contribute to the different infection outcomes presented by these strains.IMPORTANCEHowClostridium difficileestablishes and maintains colonization of the host bowel is poorly understood. Surface behaviors ofC. difficileare likely relevant during infection, representing possible interactions between the bacterium and the intestinal environment. Pili mediate bacterial interactions with various surfaces and contribute to the virulence of many pathogens. We report that type IV pili (TFP) contribute to biofilm formation byC. difficile. TFP are also required for surface motility, which has not previously been demonstrated forC. difficile. Furthermore, an epidemic-associatedC. difficilestrain showed higher pilin gene expression and greater dependence on TFP for biofilm production and surface motility. Differences in TFP regulation and their effects on surface behaviors may contribute to increased virulence in recent epidemic strains.

scholarly journals The Acinetobacter baumannii Biofilm-Associated Protein Plays a Role in Adherence to Human Epithelial Cells

2011 ◽  
Vol 80 (1) ◽  
pp. 228-233 ◽  
Author(s):  
Kari A. Brossard ◽  
Anthony A. Campagnari
Keyword(s):  
Epithelial Cells ◽  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Bacterial Colonization ◽  
Water Channel ◽  
Cell Surface Hydrophobicity ◽  
Health Care Facilities ◽  
Content Type ◽  
Abiotic Surfaces ◽  
Normal Human

ABSTRACTAcinetobacter baumanniiis a significant source of nosocomial infections worldwide. This bacterium has the ability to survive and persist on multiple abiotic surfaces in health care facilities, and once a focus has been established, this opportunistic pathogen is difficult to eradicate. This paper demonstrates that theA. baumanniibiofilm-associated protein (Bap) is necessary for mature biofilm formation on medically relevant surfaces, including polypropylene, polystyrene, and titanium. Scanning electron microscopy analyses of biofilms show that Bap is required for three-dimensional tower structure and water channel formation. In conjunction with persistence on abiotic surfaces, adherence to eukaryotic cells is an important step in bacterial colonization resulting in infection of the host. We have described Bap as the surface structure involved in adherence ofA. baumanniito both normal human bronchial epithelial cells and normal human neonatal keratinocytes. However, Bap is not involved in internalization of the bacterium in these two cell lines. Furthermore, this study shows that the presence of Bap increases the bacterial cell surface hydrophobicity. The results of this study are pertinent, as the data lead to a better understanding of the role of Bap in biofilm formation on medical surfaces and in colonization of the host.

scholarly journals Subinhibitory Concentrations of Trimethoprim and Sulfamethoxazole Prevent Biofilm Formation by Acinetobacter baumannii through Inhibition of Csu Pilus Expression

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Ki Hwan Moon ◽  
Brent S. Weber ◽  
Mario F. Feldman
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Laboratory Strain ◽  
Multidrug Resistant ◽  
Microbial Interactions ◽  
Host Cells ◽  
Content Type ◽  
Bacterial Diseases ◽  
Enzymatic Systems ◽  
Subinhibitory Concentrations

ABSTRACT Acinetobacter baumannii is emerging as a multidrug-resistant nosocomial pathogen of increasing threat to human health worldwide. Pili are important bacterial virulence factors, playing a role in attachment to host cells and biofilm formation. The Csu pilus, which is assembled via the chaperone-usher secretion system, has been studied in A. baumannii ATCC 19606. Here we show that, in opposition to previous reports, the common laboratory strain ATCC 17978 produces Csu pili. We found that, although ATCC 17978 was resistant to sulfamethoxazole (Smx) and trimethoprim (Tmp), subinhibitory concentrations of these antibiotics abolished the expression of Csu and consequently produced a dramatic reduction in biofilm formation by ATCC 17978. Smx and Tmp acted synergistically to inhibit the enzymatic systems involved in the bacterial synthesis of tetrahydrofolate (THF), which is required for the synthesis of nucleotides. The effects of these antibiotics were partially relieved by exogenous THF addition, indicating that Smx and Tmp turn off Csu assembly by inducing folate stress. We propose that, for Acinetobacter, nanomolar concentrations of Smx and Tmp represent a “danger signal.” In response to this signal, Csu expression is repressed, allowing biofilm dispersal and escape from potentially inhibitory concentrations of antibiotics. The roles of antibiotics as signaling molecules are being increasingly acknowledged, with clear implications for both the treatment of bacterial diseases and the understanding of complex microbial interactions in the environment.

scholarly journals Study of genetic diversity, biofilm formation, and detection of Carbapenemase, MBL, ESBL, and tetracycline resistance genes in multidrug-resistant Acinetobacter baumannii isolated from burn wound infections in Iran

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Reza Ranjbar ◽  
Abbas Farahani
Keyword(s):  
Antimicrobial Resistance ◽  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Tetracycline Resistance ◽  
Multidrug Resistant ◽  
Control Measures ◽  
Wound Infections ◽  
Burn Wound ◽  
Cross Sectional

Abstract Background Antimicrobial resistance in multidrug-resistant Acinetobacter baumannii (MDR-AB) isolated from burn wound infections is a major concern in intensive care or burns units worldwide, and molecular studies are considered critical strategies for control of MDR-AB outbreaks in this regard. Thus, in this study, antibiotic resistance, biofilm-forming ability, molecular epidemiology of MDR A. baumannii strains recovered from patients with burns were investigated in three major hospital centers of Iran. Methods In this cross-sectional research, 163 non-repetitive A. baumannii strains were tested for susceptibility to antimicrobial agents. Polymerase chain reaction (PCR) was performed to characterize ambler classes A, B, and D β-lactamases, ISAba1 and integrons, biofilm formation was also investigated. Clonal relatedness was analyzed using Pulsed-Field Gel Electrophoresis (PFGE). Results Among 163 A. baumannii strains collected, 94.5% of them were Carbapenem-Non-Susceptible A. baumannii (CNSAB) and also 90.1 and 52.2% of them were Metallo-β-Lactamases (MBL) and Extended-Spectrum β-Lactamases (ESBL) producing isolates, respectively. Colistin and polymyxin B exhibited excellent activity against CNSAB strains. High prevalence of blaOXA − 23-like (85.1%), blaVIM (60.5%), blaPER − 1 (42.3%), tetB (67.8%), and Class 1 integrons (65.6%) were identified in CNSAB strains. ISAba1 element was associated with 42 (25.8%) and 129 (98.5%) of blaOXA-51-like and blaOXA-23-like genes, respectively. 6 clusters with the ability to form strong biofilms were found to be dominant and endemic in our entire areas. Conclusions Results of the present study show that antimicrobial resistance in CNSAB isolates from burn wound infections in monitored hospitals in Iran is multifactorial, and also findings of the study suggested that local antibiotic prescription policies should be regularly reviewed, and efficient infection control measures should be observed. Therefore, further strengthening of surveillance of antimicrobial resistance is urgently needed in these regions.

scholarly journals Significance of a Posttranslational Modification of the PilA Protein of Geobacter sulfurreducens for Surface Attachment, Biofilm Formation, and Growth on Insoluble Extracellular Electron Acceptors

2017 ◽  
Vol 199 (8) ◽  
Author(s):  
Lubna V. Richter ◽  
Ashley E. Franks ◽  
Robert M. Weis ◽  
Steven J. Sandler
Keyword(s):  
Electron Transfer ◽  
Amino Acid ◽  
Posttranslational Modification ◽  
Biofilm Formation ◽  
Electron Acceptors ◽  
Type Iv Pili ◽  
Geobacter Sulfurreducens ◽  
Surface Attachment ◽  
Content Type ◽  
Type Iv

ABSTRACT Geobacter sulfurreducens, an anaerobic metal-reducing bacterium, possesses type IV pili. These pili are intrinsic structural elements in biofilm formation and, together with a number of c-type cytochromes, are thought to serve as conductive nanowires enabling long-range electron transfer (ET) to metal oxides and graphite anodes. Here, we report that a posttranslational modification of a nonconserved amino acid residue within the PilA protein, the structural subunit of the type IV pili, is crucial for growth on insoluble extracellular electron acceptors. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of the secreted PilA protein revealed a posttranslational modification of tyrosine-32 with a moiety of a mass consistent with a glycerophosphate group. Mutating this tyrosine into a phenylalanine inhibited cell growth with Fe(III) oxides as the sole electron acceptor. In addition, this amino acid substitution severely diminished biofilm formation on graphite surfaces and impaired current output in microbial fuel cells. These results demonstrate that the capability to attach to insoluble electron acceptors plays a crucial role for the cells' ability to utilize them. The work suggests that glycerophosphate modification of Y32 is a key factor contributing to the surface charge of type IV pili, influencing the adhesion of Geobacter to specific surfaces. IMPORTANCE Type IV pili are bacterial appendages that function in cell adhesion, virulence, twitching motility, and long-range electron transfer (ET) from bacterial cells to insoluble extracellular electron acceptors. The mechanism and role of type IV pili for ET in Geobacter sulfurreducens is still a subject of research. In this study, we identified a posttranslational modification of the major G. sulfurreducens type IV pilin, suggested to be a glycerophosphate moiety. We show that a mutant in which the glycerophosphate-modified tyrosine-32 is replaced with a phenylalanine has reduced abilities for ET and biofilm formation compared with those of the wild type. The results show the importance of the glycerophosphate-modified tyrosine for surface attachment and electron transfer in electrode- or Fe(III)-respiring G. sulfurreducens cells.

scholarly journals Complete Genome Sequence of Multidrug-Resistant Acinetobacter baumannii Strain 1656-2, Which Forms Sturdy Biofilm

2011 ◽  
Vol 193 (22) ◽  
pp. 6393-6394 ◽  
Author(s):  
Jin Yeol Park ◽  
Shukho Kim ◽  
Sung-Min Kim ◽  
Sun Ho Cha ◽  
Si-Kyu Lim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Biofilm Formation ◽  
Complete Genome ◽  
Multidrug Resistant ◽  
Negative Bacterium ◽  
Content Type ◽  
Multiple Drugs ◽  
Insight Into

Acinetobacter baumanniiis a Gram-negative bacterium causing nosocomial infections worldwide. To gain quick insight into the molecular basis of biofilm formation inA. baumannii, we determined the complete genome sequence ofA. baumanniistrain 1656-2, which forms sturdy biofilm and is resistant to multiple drugs.

Sign in / Sign up

Export Citation Format

Share Document