Opportunistic Gram-negative rods' capability of creating biofilm structures on polivynyl chloride and styrene-acronitrile copolymer surfaces.

Biofilms are highly organized microbial communities displaying high resistance to disinfectants and other external environmental factors. Medical equipment, such as stents and catheters, can be colonized by a variety of bacteria including opportunistic pathogens circulating in the environment and dangerous to immunocompromised patients. Application of materials resistant to biofilm formation will minimize the risk of patients' infection. Hence, the aim of this research was to determine the biofilm growth of environmental bacteria isolates on polyvinyl chloride and styrene-acronitrile copolymer surfaces. Nine strains (Pseudomonas aeruginosa, Burkholderia cepacia and Serratia liquefacies) isolated from cosmetics, and a reference P. aeruginosa strain ATCC 15442, were tested. The ability and dynamics of biofilm formation on intubation catheters (30°C, up to 24 h) in bacterial growth cultures (10(7)-10(8) CFU/ml) was investigated, with subsequent sonication and quantification by agar plate count method. The results indicated that all the tested bacteria expressed a strong ability for the polymer surface adhesion, reaching 4.6 to 6.7 log CFU/cm(2) after 30 minutes. Moreover, for the majority of strains, the level of 24-hour biofilm production was from 6.67-7.61 log CFU/cm(2). This research indicates that the environmental strains circulating between the cosmetics and patients may pose a threat of biofilm formation on medical equipment surfaces, and presumably in the clinical surroundings as well.

Evaluation of hydrophobicity and quantitative analysis of biofilm formation by Alicyclobacillus sp.

Alicyclobacillus sp. are acidothermophilic bacteria frequently contaminating fruit based products (juices and juice concentrates). These sporulating bacteria are able to survive at elevated temperatures and highly acidic environments which causes difficulties in their removal from industrial environments. Although numerous literature data examine Alicyclobacillus sp. presence in fruit based products and methods of their elimination, there is still a limited knowledge on ability of these bacteria to adhere to abiotic surfaces. Therefore, the objective of this study was to determine Alicyclobacillus sp. cells' hydrophobicity and capability of biofilm formation on a glass surface. The degree of cells hydrophobicity, according to Microbial Adhesion to Hydrocarbon (MATH) and Salt Aggregation Test (SAT), was investigated for eleven environmental isolates from natural Polish habitats, identified as Alicyclobacillus sp., and a Alicyclobacillus acidoterrestris DSM 3922 reference strain. The dynamics of biofilm formation within 3-day incubation on a glass surface was evaluated and quantified by a plate count method both, for cultures with and without agitation. All of the bacterial strains tested expressed ability to colonize a glass surface and four environmental isolates were classified as fast-adherent strains. The mature biofilm structures were predominantly formed after 48 hours of incubation. Dynamic culturing conditions were observed to accelerate the biofilm formation. The majority of strains expressed a moderate hydrophobicity level both, in SAT (41.7%) and MATH-PBS (75.0%), as well as MATH-PUM (91.7%) tests. However, no correlation between hydrophobicity and cell adherence to a glass slide surface was observed.