Virulence determinants and biofilm formation of Acinetobacter baumannii isolated from hospitalized patients

Aliramezani, Amir; Soleimani, Mohammad; Fard, Ramin Mazaheri Nezhad; Nojoomi, Farshad

doi:10.18683/germs.2019.1171

Cited by 19 publications

(13 citation statements)

References 19 publications

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“…Of these, the majority were due to Acinetobacter baumannii, similar to previous reports [13,35]. The importance of these bacteria has increased in recent years due to its great capacity to acquire mechanisms of resistance to different classes of antibiotics, great ability to survive and adapt to adverse conditions, and ability to adhere to different surfaces by the formation of bio lms [36]. This series con rms that Acinetobacter baumannii is resistant to several antimicrobials, except for imipenem.…”

Section: Discussionsupporting

confidence: 83%

Predictive factors of outcome following nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Santos

Hernandes

Montelli

et al. 2020

Preprint

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Background Peritonitis due to gram-negative bacilli (GNB), particularly nonfermenting GNB (NF-GNB), is a serious complication of peritoneal dialysis (PD) with a low resolution rate. Beyond the patient’s condition, microbiological properties such as antimicrobial resistance, biofilms and the production of other virulence factors can explain the bad outcomes. This study aimed to evaluate the influence of the patient’s condition, the microbiological characteristics, including biofilm production, and the treatment of peritonitis on peritonitis resolution.Methods We reviewed the records of 62 new peritonitis episodes caused by NF-GNB that occurred between 1997 and 2015 at a single university center. The influence of microbiological and clinical factors on resolution chance was analyzed by logistic regression.Results The etiologies were species of Pseudomonas (51.6%), Acinetobacter (32.2%), and others (16.1%). There was a high (72.9%) proportion of biofilm producers’ lineages. The in vitro susceptibility rate of Pseudomonas spp. to amikacin, ciprofloxacin, and ceftazidime was significantly greater than that of Acinetobacter spp. and other species; however, there was a similar low resolution rate (<45%) among the episodes attributable to Pseudomonas spp, Acinetobacter spp, and other NF-GNB. Pre-existent exit-site infection was independently associated with nonresolution. No other factor, including biofilm production, was associated with the outcome. Conclusions Peritonitis due to NF-GNB in PD is a severe infection with a reduced resolution rate, and pre-existent exit site infection negatively influences the chance of resolution. The higher in vitro susceptibility of Pseudomonas compared to that of other NF-GNB with a similar resolution rate, suggests bacterial virulence factors beyond biofilm and can act in concert, thereby worsening the outcome.

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Section: Discussionsupporting

confidence: 83%

Predictive factors of outcome following nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Santos

Hernandes

Montelli

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…Of these, the majority were due to Acinetobacter baumannii , similar to previous reports 13 , 30 . The importance of these bacteria has increased in recent years due to their great capacity to acquire mechanisms of resistance to different classes of antibiotics, great ability to survive and adapt to adverse conditions, and ability to adhere to different surfaces by the formation of biofilms 31 . This series confirms that Acinetobacter baumannii is resistant to several antimicrobials, except imipenem.…”

Section: Discussionmentioning

confidence: 99%

Clinical and microbiological factors predicting outcomes of nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Santos

Hernandes

Montelli

et al. 2021

Sci Rep

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Peritonitis due to gram-negative bacilli (GNB), particularly nonfermenting GNB (NF-GNB), is a serious complication of peritoneal dialysis with a low resolution rate. Beyond the patient’s condition, microbiological properties such as antimicrobial resistance, biofilm production and other virulence factors can explain the poor outcomes. This study aimed to evaluate the influence of patient condition, microbiological characteristics, including biofilm production, and treatment on peritonitis outcome. We reviewed the records of 62 index episodes caused by NF-GNB that occurred between 1997 and 2015 in our center. The etiologies were species of Pseudomonas (51.6%), Acinetobacter (32.2%), and other NF-GNB (16.1%). There was a high (72.9%) proportion of biofilm producer lineages. The in vitro susceptibility rate of Pseudomonas spp. to amikacin, ciprofloxacin, and ceftazidime was significantly greater than that of Acinetobacter spp. and other species; however, there was a similar low resolution rate (< 45%) among the episodes attributable to them. Preexisting exit-site infection was independently associated with nonresolution. No other factor, including biofilm production, was associated with the outcome. The higher in vitro susceptibility of Pseudomonas compared to other NF-GNB that presented a similar resolution rate suggests that bacterial virulence factors such as biofilms can act in concert, thereby worsening the outcome.

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“… 7 In recent years, the number of BP-AB infections has been climbing. 8 Due to the extremely limited number of antibiotics to treat BP-AB infections, mortality has increased. 8 …”

Section: Introductionmentioning

confidence: 99%

“… 8 Due to the extremely limited number of antibiotics to treat BP-AB infections, mortality has increased. 8 …”

Section: Introductionmentioning

confidence: 99%

“…7 In recent years, the number of BP-AB infections has been climbing. 8 Due to the extremely limited number of antibiotics to treat BP-AB infections, mortality has increased. 8 One of the major and pivotal characteristics of BP-AB is the ability to form biofilms on biotic and abiotic surfaces, which is the primary cause of its resistance and persistence.…”

Section: Introductionmentioning

confidence: 99%

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Myrtenol Inhibits Biofilm Formation and Virulence in the Drug-Resistant Acinetobacter baumannii: Insights into the Molecular Mechanisms

Liu¹,

Liu²,

Li³

et al. 2022

IDR

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Background blaNDM-1 -producing Acinetobacter baumannii (BP-AB) remains a critical problem in nosocomial infections, because of its resistance mediated by the biofilm formation and virulence factors. No studies have confirmed myrtenol’s efficacy in inhibiting the biofilm formation and virulence associated with biofilm of BP-AB. Methods The tested concentrations of myrtenol were wild type (A), 50 μg/mL (B), 100 μg/mL (C), 200 μg/mL (D), 250 μg/mL (E), and 300 μg/mL (F). Results The BP-AB biofilm inhibition was significantly higher in the D, E, and F groups than in the A, B, and C groups. Myrtenol significantly reduced the air-liquid interface ring formation in glass tubes. It also effectively inhibited the attachment of BP-AB strains on polystyrene surfaces as shown by crystal violet staining. Microscopy showed a significant reduction in biofilm formation with dispersed BP-AB strains. The confocal laser scanning microscopy analysis showed a significant reduction in the biofilm’s biomass, covered surface area, and thickness. The scanning electron microscopy analysis revealed significantly fewer BP-AB aggregates on the coverslip surface. In the CompStat analysis, the biofilm’s biomass, maximum thickness, and surface-to-volume ratio were significantly reduced. The qPCR analysis revealed a significant down-regulation of bfmR, bap, csuA/B, and ompA expression, which positively correlated with the biofilm’s biomass, maximum thickness, and surface-to-volume ratio in BP-AB strains. Myrtenol significantly improved the susceptibility of BP-AB to the antibiotics amikacin, piperacillin/tazobactam, cefoperazone/sulbactam, and ceftazidime. Conclusion Myrtenol attenuates the BP-AB biofilm formation and virulence by suppressing the expression of bfmR, bap, csuA/B, and ompA.

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Virulence determinants and biofilm formation of Acinetobacter baumannii isolated from hospitalized patients

Cited by 19 publications

References 19 publications

Predictive factors of outcome following nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Predictive factors of outcome following nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Clinical and microbiological factors predicting outcomes of nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Myrtenol Inhibits Biofilm Formation and Virulence in the Drug-Resistant Acinetobacter baumannii: Insights into the Molecular Mechanisms

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