In -vitro Biofilm Formation of Vaginal Isolates of Streptococcus agalactiae; Effect of pH and Culture Media

Staphylococcus aureus (S. aureus) causes persistent biofilm-related infections. Biofilm formation by S. aureus is affected by the culture conditions and is associated with certain genotypic characteristics. Here, we show that glucose and sodium chloride (NaCl) supplementation of culture media, a common practice in studies of biofilms in vitro, influences both biofilm formation by 40 S. aureus clinical isolates (methicillin-resistant and methicillin-sensitive S. aureus) and causes variations in biofilm quantification. Methicillin-resistant strains formed more robust biofilms than methicillin-sensitive strains in tryptic soy broth (TSB). However, glucose supplementation in TSB greatly promoted and stabilized biofilm formation of all strains, while additional NaCl was less efficient in this respect and resulted in significant variation in biofilm measurements. In addition, we observed that the ST239-SCCmec (Staphylococcal Cassette Chromosome mec) type III lineage formed strong biofilms in TSB supplemented with glucose and NaCl. Links between biofilm formation and accessory gene regulator (agr) status, as assessed by δ-toxin production, and with mannitol fermentation were not found. Our results show that TSB supplemented with 1.0% glucose supports robust biofilm production and reproducible quantification of S. aureus biofilm formation in vitro, whereas additional NaCl results in major variations in measurements of biofilm formation.

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Acidic pH Strongly EnhancesIn VitroBiofilm Formation by a Subset of Hypervirulent ST-17 Streptococcus agalactiae Strains

Applied and Environmental Microbiology ◽

10.1128/aem.03627-13 ◽

2014 ◽

Vol 80 (7) ◽

pp. 2176-2185 ◽

Cited By ~ 44

Author(s):

Nunzia D'Urzo ◽

Manuele Martinelli ◽

Alfredo Pezzicoli ◽

Virginia De Cesare ◽

Vittoria Pinto ◽

...

Keyword(s):

Streptococcus Agalactiae ◽

Biofilm Formation ◽

Medium Composition ◽

Proteinase K ◽

Neonatal Meningitis ◽

Neonatal Infections ◽

Content Type ◽

Acidic Conditions ◽

Group B

ABSTRACTStreptococcus agalactiae, also known as group BStreptococcus(GBS), is a primary colonizer of the anogenital mucosa of up to 40% of healthy women and an important cause of invasive neonatal infections worldwide. Among the 10 known capsular serotypes, GBS type III accounts for 30 to 76% of the cases of neonatal meningitis. In recent years, the ability of GBS to form biofilm attracted attention for its possible role in fitness and virulence. Here, a newin vitrobiofilm formation protocol was developed to guarantee more stringent conditions, to better discriminate between strong-, low-, and non-biofilm-forming strains, and to facilitate interpretation of data. This protocol was used to screen the biofilm-forming abilities of 366 GBS clinical isolates from pregnant women and from neonatal infections of different serotypes in relation to medium composition and pH. The results identified a subset of isolates of serotypes III and V that formed strong biofilms under acidic conditions. Importantly, the best biofilm formers belonged to serotype III hypervirulent clone ST-17. Moreover, the abilities of proteinase K to strongly inhibit biofilm formation and to disaggregate mature biofilms suggested that proteins play an essential role in promoting GBS biofilm initiation and contribute to biofilm structural stability.

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P45: Glucose stimulates Streptococcus agalactiae biofilm formation and promotes in vitro vaginal cell colonization

American Journal of Reproductive Immunology ◽

10.1111/aji.43_13420 ◽

2021 ◽

Vol 85 (S1) ◽

pp. 84-84

Keyword(s):

Streptococcus Agalactiae ◽

Biofilm Formation ◽

Cell Colonization

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Analysis of the bacterial biofilm formation in different models of the in vitro culture

European Journal of Clinical and Experimental Medicine ◽

10.15584/ejcem.2021.1.6 ◽

2021 ◽

Vol 19 (1) ◽

pp. 40-45

Author(s):

Agnieszka Bogut ◽

◽

Agnieszka Magryś ◽

Keyword(s):

Biofilm Formation ◽

Culture Media ◽

Microtiter Plate ◽

Bacterial Biofilm ◽

Atmospheric Conditions ◽

Experimental Conditions ◽

Microtiter Plate Assay ◽

Biofilm Production ◽

Strain Type

Introduction. Microtiter plate assay (MPA) remains one of workhorses of in vitro biofilm research but it requires optimization of experimental conditions to fulfill the biofilm formation requirements of different bacterial pathogens. Aim. The aim was to determine the effect of TSB and RPMI1640 culture media and selected culture variables (O2 vs. 5% CO2, extended incubation time) on the biofilm production by bacteria commonly involved in biofilm-related infections: Enterococcus faecalis (EF), Escherichia coli (EC), Staphylococcus aureus (SA), Pseudomonas aeruginosa (PA), Klebsiella pneumoniae (KP). Material and methods. The investigation was performed using the MPA with crystal violet. Results. Statistically significant (p<0.05) increase in biofilm production between 24h and 72h time points was observed for EF (TSB o2, RPMIo2 and RPMIco2), EC (TSBo2), SA (TSBo2, TSBco2), KP (TSBo2, TSBco2), PA (RPMIco2, TSBco2). The TSB caused a significantly greater stimulation of biofilm production compared to RPM1640. It outcompeted RPMI1640 irrespective of the atmospheric conditions for SA and KP and under aerobic conditions for EF. Conclusion. Although the TSB provided the most optimal conditions for biofilm production, the process was influenced by the strain type, atmospheric conditions and period of cultivation which limits the ability to design a single universal model of the in vitro biofilm investigation.

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Influence of Laboratory Culture Media on in vitro Growth, Adhesion, and Biofilm Formation of Pseudomonas aeruginosa and Staphylococcus aureus

Medical Principles and Practice ◽

10.1159/000494757 ◽

2018 ◽

Vol 28 (1) ◽

pp. 28-35 ◽

Cited By ~ 14

Author(s):

Gayan Wijesinghe ◽

Ayomi Dilhari ◽

Buddhika Gayani ◽

Nilwala Kottegoda ◽

Lakshman Samaranayake ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Culture Media ◽

Brain Heart Infusion ◽

Sem Images ◽

Planktonic Growth ◽

Initial Adhesion ◽

And Staphylococcus Aureus

Objective: Pseudomonas aeruginosa and Staphylococcus aureus dual-species biofilm infections are notoriously difficult to manage. This study aimed at investigating the influence of four different culture media on the planktonic growth, adhesion, and biofilm formation of P. aeruginosa and S. aureus. Materials and Methods: We monitored four different culture media including Nutrient Broth, Brain Heart Infusion (BHI) broth, Luria-Bertani broth, and RPMI 1640 medium on the planktonic growth, adhesion, and biofilm formation of P. aeruginosa (ATCC 27853) and S. aureus (ATCC 25923) using MTT assay and scanning electron microscopy (SEM). Results: The most robust growth of the mono- and dual-species cultures was noted in BHI broth. On the contrary, RPMI 1640 medium promoted maximal initial adhesion of both the mono- and dual-species, but BHI broth fostered the maximal biofilm growth. SEM images showed profuse extracellular polysaccharide production in biofilms, particularly in coculture, in BHI medium. Conclusion: Our data demonstrate that BHI broth, relative to the other tested media, is the most conducive for in vitro evaluation of biofilm and planktonic growth kinetics of these two pathogens, both in mono- and coculture.

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Influence of Culture Media on Biofilm Formation byCandidaSpecies and Response of Sessile Cells to Antifungals and Oxidative Stress

BioMed Research International ◽

10.1155/2015/783639 ◽

2015 ◽

Vol 2015 ◽

pp. 1-15 ◽

Cited By ~ 27

Author(s):

Isela Serrano-Fujarte ◽

Everardo López-Romero ◽

Georgina Elena Reyna-López ◽

Ma. Alejandrina Martínez-Gámez ◽

Arturo Vega-González ◽

...

Keyword(s):

Biofilm Formation ◽

Culture Media ◽

Planktonic Cells ◽

Human Immune System ◽

Xtt Assay ◽

Nutritional Conditions ◽

Complex Process ◽

Sessile Cells

The aims of the study were to evaluate the influence of culture media on biofilm formation byC. albicans, C. glabrata, C. krusei,andC. parapsilosisand to investigate the responses of sessile cells to antifungals and reactive oxygen species (ROS) as compared to planktonic cells. For biofilm formation, theCandidaspecies were grown at different periods of time in YP or YNB media supplemented or not with 0.2 or 2% glucose. Sessile and planktonic cells were exposed to increasing concentrations of antifungals, H2O2, menadione or silver nanoparticles (AgNPs). Biofilms were observed by scanning electron microscopy (SEM) and quantified by the XTT assay.C. albicansformed biofilms preferentially in YPD containing 2% glucose (YPD/2%),C. glabratain glucose-free YNB or supplemented with 0.2% glucose (YNB/0.2%), whileC. kruseiandC. parapsilosispreferred YP, YPD/0.2%, and YPD/2%. Interestingly, onlyC. albicansproduced an exopolymeric matrix. This is the first report dealing with thein vitroeffect of the culture medium and glucose on the formation of biofilms in fourCandidaspecies as well as the resistance of sessile cells to antifungals, AgNPs, and ROS. Our results suggest that candidiasisin vivois a multifactorial and complex process where the nutritional conditions, the human immune system, and the adaptability of the pathogen should be considered altogether to provide an effective treatment of the patient.

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In vitro effect of pH on resistance of ruminal bacteria to intracellular potassium depletion, and effect of pH and ionophores on ammonia and microbial protein production

Arquivo Brasileiro de Medicina Veterinária e Zootecnia ◽

10.1590/s0102-09352005000600012 ◽

2005 ◽

Vol 57 (6) ◽

pp. 778-783 ◽

Cited By ~ 1

Author(s):

W.M. Leopoldino ◽

R.P. Lana ◽

A.C. Borges ◽

H.C. Mantovani ◽

R.M.A. Teixeira ◽

...

Keyword(s):

Protein Production ◽

Culture Media ◽

Low Ph ◽

Potassium Depletion ◽

Ammonia Production ◽

Microbial Protein ◽

Ruminal Bacteria ◽

Effect Of Ph ◽

Vitro Effect

Ruminal fluid from steers fed on pasture was incubated with artificial media at pH 5.5 and 7.0 in two experiments. In the first, the effect of monensin level on resistance of ruminal bacteria to potassium depletion was evaluated; in the second, effects of the ionophores monensin and lasalocid on ammonia and protein production were quantified. In experiment 1, culture media affected potassium level. The monensin concentration needed to cause half maximal potassium depletion was 2.77µM at pH 5.5 but was 0.056µM at pH 7.0, showing that bacteria incubated at pH 5.5 were more tolerant to monensin than those incubated at pH 7.0. Both ionophores as well as increased acidity caused decreased ammonia production. Both ionophores inhibited ammonia production by 56%, independently of pH. In cultures incubated at pH 5.5 compared to pH 7.0, ammonia production was decreased by 50.5%, independently of the ionophores. Therefore, effects of ionophores and acidity were additive, and the maximum inhibition occurred in the presence of an ionophore at low pH (75.2%). Microbial protein production was lowest when lasalocid was present in a low pH culture medium, causing inhibition of microbial growth.

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