Mature Pseudomonas aeruginosa Biofilms Prevail Compared to Young Biofilms in the Presence of Ceftazidime

Eravacycline (formerly TP-434) was evaluated in vitro against pre-established biofilms formed by a uropathogenic Escherichia coli strain. Biofilms were eradicated by 0.5 g/ml eravacycline, which was within 2-fold of the MIC for planktonic cells. In contrast, colistin and meropenem disrupted biofilms at 32 and 2 g/ml, respectively, concentrations well above their respective MICs of 0.5 and 0.03 g/ml. Gentamicin and levofloxacin eradicated biofilms at concentrations within 2-fold of their MICs. Many bacterial pathogens associated with chronic infections can persist as inherently antibiotic-and host defensetolerant biofilms, embedded in complex extracellular matrices attached to inert surfaces, dead or living tissue, and medical devices during mild or serious infections (1-5). Biofilm-like intracellular bacterial communities have also been observed within infection sites, such as bladder cells in urinary tract infections and epithelial cells in respiratory infections (6-8).Restricted antibiotic diffusion across the extracellular matrix, upregulation of intrinsic efflux pumps, generally lower metabolic activity, and the presence of persister cells are all thought to be significant factors contributing to increased antimicrobial tolerance of bacteria growing in biofilms (5, 7, 9 10).Eravacycline is a novel broad-spectrum fluorocycline with in vitro activity against emerging multidrug-resistant Gramnegative pathogens, including carbapenem-resistant and extended-spectrum ␤-lactamase (ESBL)-producing Enterobacteriaceae and Acinetobacter baumannii (11). Eravacycline is currently in phase 3 clinical studies for complicated urinary tract infections and complicated intra-abdominal infections. The present study was undertaken to characterize the activity in vitro of eravacycline, and several other antibiotics commonly used in treatment of infections caused by Gram-negative bacteria against biofilms formed by a uropathogenic, tetracycline-resistant, ␤-lactamase-producing Escherichia coli isolate, EC200 (ATCC BAA-1161) [tet(B) bla TEM ].For biofilm assays, cells from a fresh tryptic soy agar (TSA; BBL BD no. 221283) plate grown overnight at 35°C were suspended in 0.9% saline to a 0.5 McFarland standard, diluted 10-fold into tryptic soy broth (TSB)-1% yeast extract (YE) medium (Bacto BD no. 211825 [TSB] and no. 210929 [YE]) and grown at 35°C to log phase for 2 h. The culture was diluted 1/100 in TSB-YE to ϳ10 6 CFU/ml, and 500 l of culture was added to 5-ml round-bottom polystyrene tubes (BD Falcon no. 352054; BD, Franklin Lakes, NJ). After 24 h of stationary incubation at 35°C, the EC200 biofilm formed as a ring of growth on the walls of the tube at the liquid-air interface (Fig. 1A). All subsequent manipulations of tubes for biofilm staining and CFU quantification (see below) were done with care to avoid disrupting the adhered biofilm. After 24 h of growth,

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“…2B and E and Table 1). Results with comparator antibiotics were similar to findings reported for Pseudomonas aeruginosa biofilms (15)(16)(17).…”

supporting

confidence: 79%

Eravacycline (TP-434) Is Active In Vitro against Biofilms Formed by Uropathogenic Escherichia coli

Grossman

O’Brien

Kerstein

et al. 2015

Antimicrob Agents Chemother

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“…aeruginosa, some considered 4 h biofilm as young and 24 h as mature (22), while others considered 24 h as young and 12 days biofilm as mature (20). Similarly, 6 h S. aureus biofilm was considered as young and 24 h as mature (23), whereas some considered 7 days old biofilm as mature (24).…”

Section: Biofilm Agementioning

confidence: 99%

Influence of biofilm growth age, media and antibiotics exposure time on Staphylococcus aureus and Pseudomonas aeruginosa biofilm removal in vitro

Chen¹,

Xu²,

Winkler³

et al. 2020

Preprint

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Biofilm is known to be tolerant towards antibiotics and difficult to eradicate. Numerous studies have reported Minimum Biofilm Eradication Concentration (MBEC) values of antibiotics for many known biofilm pathogens. However, the experimental parameters applied in these studies differ considerably, and often the rationale behind the experimental design are not well described. This makes it difficult to compare the findings. To demonstrate the importance of experimental parameters, we investigated the influence of biofilm growth age, antibiotic treatment duration and growth media on biofilm eradication in this study. The commonly used biofilm model Calgary biofilm device was used to grow 24 h and 72 h biofilms of Staphylococcus aureus and Pseudomonas aeruginosa , which were treated with time-dependent vancomycin and concentration-dependent tobramycin, respectively. Two common bacteriological growth media Tryptic Soy Broth (TSB) and Cation-adjusted Mueller Hinton Broth (CaMHB) were tested. We found for both species that biofilms were more difficult to kill in TSB than in CaMHB. Furthermore, young biofilms (24 h) were easier to eradicate than old biofilms (72 h). In agreement with vancomycin being time-dependent, extension of the vancomycin exposure increased killing of S. aureus biofilms. Tobramycin treatment of 24 h P. aeruginosa biofilms was found concentration-dependent and time-independent, however, increasing killing was indicated for 72 h P. aeruginosa biofilms. This study demonstrated biofilm removal efficacy was influenced by media, biofilm age and antibiotics treatment duration. It is therefore necessary to taking these parameters into consideration when designing experiments.

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“…The increased tolerance of mature biofilm against antibiotics has emphasized the importance of early treatment and correct choice of antibiotics for P. aeruginosa biofilm infections (Bowler et al, 2012). Three-day-old biofilms were significantly more tolerant to treatment with 8 mg L À1 ciprofloxacin than one-day-old biofilms: the surviving fraction 38% compared with 19%, P < 0.001).…”

Section: Introductionmentioning

confidence: 99%

Formation of hydroxyl radicals contributes to the bactericidal activity of ciprofloxacin againstPseudomonas aeruginosabiofilms

et al. 2014

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Antibiotic-tolerant, biofilm-forming Pseudomonas aeruginosa has long been recognized as a major cause of chronic lung infections of cystic fibrosis patients. The mechanisms involved in the activity of antibiotics on biofilm are not completely clear. We have investigated whether the proposed induction of cytotoxic hydroxyl radicals (OH˙) during antibiotic treatment of planktonically grown cells may contribute to action of the commonly used antibiotic ciprofloxacin on P. aeruginosa biofilms. For this purpose, WT PAO1, a catalase deficient ΔkatA and a ciprofloxacin resistant mutant of PAO1 (gyrA), were grown as biofilms in microtiter plates and treated with ciprofloxacin. Formation of OH˙ and total amount of reactive oxygen species (ROS) was measured and viability was estimated. Formation of OH˙ and total ROS in PAO1 biofilms treated with ciprofloxacin was shown but higher levels were measured in ΔkatA biofilms, and no ROS production was seen in the gyrA biofilms. Treatment with ciprofloxacin decreased the viability of PAO1 and ΔkatA biofilms but not of gyrA biofilms. Addition of thiourea, a OH˙ scavenger, decreased the OH˙ levels and killing of PAO1 biofilm. Our study shows that OH˙ is produced by P. aeruginosa biofilms treated with ciprofloxacin, which may contribute to the killing of biofilm subpopulations.

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Mature Pseudomonas aeruginosa Biofilms Prevail Compared to Young Biofilms in the Presence of Ceftazidime

Cited by 52 publications

References 14 publications

Eravacycline (TP-434) Is Active In Vitro against Biofilms Formed by Uropathogenic Escherichia coli

Eravacycline (TP-434) Is Active In Vitro against Biofilms Formed by Uropathogenic Escherichia coli

Influence of biofilm growth age, media and antibiotics exposure time on Staphylococcus aureus and Pseudomonas aeruginosa biofilm removal in vitro

Formation of hydroxyl radicals contributes to the bactericidal activity of ciprofloxacin againstPseudomonas aeruginosabiofilms

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