Verticalization of bacterial biofilms

Biofilms are communities of bacteria adhered to surfaces. Recently, biofilms of rod-shaped bacteria were observed at single-cell resolution and shown to develop from a disordered, two-dimensional layer of founder cells into a three-dimensional structure with a vertically-aligned core. Here, we elucidate the physical mechanism underpinning this transition using a combination of agent-based and continuum modeling. We find that verticalization proceeds through a series of localized mechanical instabilities on the cellular scale. For short cells, these instabilities are primarily triggered by cell division, whereas long cells are more likely to be peeled off the surface by nearby vertical cells, creating an "inverse domino effect". The interplay between cell growth and cell verticalization gives rise to an exotic mechanical state in which the effective surface pressure becomes constant throughout the growing core of the biofilm surface layer. This dynamical isobaricity determines the expansion speed of a biofilm cluster and thereby governs how cells access the third dimension. In particular, theory predicts that a longer average cell length yields more rapidly expanding, flatter biofilms. We experimentally show that such changes in biofilm development occur by exploiting chemicals that modulate cell length.Comment: Main text 10 pages, 4 figures; Supplementary Information 35 pages, 15 figure

Bacterial Biofilm and its Clinical Implications

Microbial biofilm created huge burden in treatment of both community and hospital infections. A biofilm is complex communities of bacteria attached to a surface or interface enclosed in an exopolysaccharide matrix and protected from unfavorable conditions such as presence of antibiotics, host defense or oxidative stresses. Biofilms are often considered hot spot for horizontal gene transfer among same or different bacterial species. Furthermore, bacteria with increased hydrophobicity facilitate biofilm formation by reducing repulsion between the extracellular matrix and the bacterium. There is a marked increase in the rate of persons nonresponsive to antibiotic therapy for infections of the Urinary Tract (UTIs), burns and upper respiratory tract due to biofilm formations. It is estimated that 90% of nosocomial infections are mediated by biofilm. The role of biofilm in infections has become so great that the treatment of such antibiotic resistance infections is proving difficult and costly to health care systems. The biofilm related infections varied from dental plaque, destruction of prosthetic valve to death of cystic fibrosis patients. This review aims to provide a summary of role of bacterial biofilm and its clinical implications for the patients

Persistence of porcine reproductive and respiratory syndrome virus and porcine circovirus type 2 in bacterial biofilms

The aim of this pilot project was to investigate association of viruses with bacterial biofilms. Our preliminary data indicate that important viral pathogens of swine, namely, porcine reproductive and respiratory syndrome virus and porcine circovirus type 2, can associate with and persist within bacterial biofilms for several days

Methods for eradication of the biofilms formed by opportunistic pathogens using novel techniques – A review

The inconvenient environmental conditions force microorganisms to colonize either abiotic surfaces or animal and plant tissues and, therefore, form more resistant structures – biofilms. The phenomenon of microbial adherence, opportunistic pathogens in particular, is of a great concern. Colonization of medical devices and biofilm formation on their surface, may lead to severe infections mainly in humans with impaired immune system. Although, current research consider various methods for prevention of microbial biofilms formation, still, once a biofilm is formed, its elimination is almost impossible. This study focuses on the overview of novel methods applied for eradication of mature opportunistic pathogens' biofilms. Among various techniques the following: cold plasma, electric field, ultrasounds, ozonated water treatment, phagotherapy, matrix targeting enzymes, bacteriocins, synthetic chemicals and natural origin compounds used for biofilm matrix disruption were briefly described

Persistent middle ear effusion presumably biofilm-related in a paediatric patient with common variable immunodeficiency

Bacterial biofilms play a role in upper respiratory tract diseases, including acute and chronic middle ear diseases, and are involved in chronic infections and resistance to antibiotic treatment. In particular, the nasopharynx and the surrounding tissues act as important reservoirs of resistant bacterial biofilms, which have been detected in biopsies taken from adenoid and/or middle ear mucosa of children with chronic middle ear effusion. Here we describe the management of a child with congenital immunodeficiency and a chronic middle ear effusion, resistant to traditional medical treatment and presumably due to nasopharyngeal colonization by bacterial biofilms, which has been successfully treated by means of medicated nasal douches delivering antibiotic and a biofilm-destroying compound

Resistance of S. Aureus Atcc 25923, E. Coli 055k59 No. 3912/41 and P. Aeruginosa 27/99 to the Wash-disinfectant «Milkodez»

The aim of the work – the article presents the results of determining of the resistance of S. aureus ATCC 25923, E. coli 055K59 No. 3912/4 and P. aeruginosa 27/99 test cultures in planktonic form and in biofilm to our developed «Milkodez» acid detergent.Materials and methods. Microbial biofilms were grown on MPB in 5 cm disposable plastic Petri dishes. To determine the effect of disinfectants on microbial biofilms, 3 Petri dishes with biofilms of each of the test cultures were used. One of the Petri dishes served as control and she had for 15 minutes made 5 cm3 of saline NaCl solution, in the second – 5 cm3 of hot water (t=70±5 °C), and in the third – 5 cm3 of acidic detergent «Milkodez». Microbial biofilms were fixed for 10 min. 96º with ethyl alcohol for 10 min. were stained with a 0.1 % solution of crystalline violet, and the remnants of the unabsorbed paint were removed with phosphate buffer. The biofilm dye was extracted with 96º of ethyl alcohol, which was photocolometrically investigated at 570 nm to establish the density of the formed biofilms. The density of the formed microbial biofilms was considered low in optical density of the extract up to 0.5 units, average – from 0.5 to 1.0 units; and high – over 1.0 unitsThe resistance of planktonic forms of test cultures of microorganisms to disinfectants was determined in sterile tubes, which made 10 cm3 (t=70±5 °C) of 0.5 % of their working solutions and 0.1 cm3 (1 billion microbial bodies) of the standard test – cultures. The culture was maintained for 15 min. and made ten – fold plantings on IPA in Petri dishes.Incubation of mesophilic microorganisms was carried out in a thermostat at a temperature of 30 °C, and psychrophilic – 20 °C. After 48 hours the calculation of the growing colonies were carried out. The results were expressed in colony forming units (CFU).Results. Due to the impact on microbial biofilms formed by the test cultures of S. aureus ATCC 25923, E. coli 055K59 No. 3912/41 and P. aeruginosa 27/99 for 15 min. 0.5 % solution of acid detergent «Milkodez» the optical density of the solutions was respectively 0.64, 0.72, 0.45 units. The results obtained indicate that the melkodez caused a decrease in the biofilm–forming ability of S. aureus ATCC 25923 3.2 times, in E. coli 055K59 No. 3912/41 – 1,7 times and in P. aeruginosa 27/99 – 2.8 times, compared to control. However, the density of one – day microbial biofilms formed by S. aureus ATCC 25923 and E. coli 055K59 No. 3912/41 was medium, and P. aeruginosa 27/99 was low. It has been proven that the «Milkodez» acid detergent developed is more effective than the prototype «Hypracid», since it caused the death of 100 % of planktonic test cultures and the number of S. aureus ATCC 25923, E. coli 055K59 No. 3912/41 and P. aeruginosa 27/99 formed in the biofilm that survived after its application was 2.7, 3.2 and 1.4 times lower, respectively.Conclusions. It was found that the test cultures were able to form high – density biofilms, since the optical density of the extract in the control was in the range from 1.28 to 2.05 units, which is greater than 1.0 units. Acid wash detergent «Milkodez» for 15 minutes of exposure causes the formation of S. aureus ATCC 25923, E. coli 055K59 No. 3912/41 and P. aeruginosa 27/99 biofilms of low and medium density and reduces their biofilm capacity by 3.2, 1.7 and 2.8 times, respectively. Its use provides the death of 100 % of the planktonic forms of the test cultures under study and reduces their number in the biofilm by 2.7, 3.2 and 1,4 times more, respectively, compared to «Hypracid» detergent