No abstract

Biofilms play an essential role in chronic and healthcare-associated infections and are more resistant to antimicrobials compared to their planktonic counterparts due to their (1) physiological state, (2) cell density, (3) quorum sensing abilities, (4) presence of extracellular matrix, (5) upregulation of drug efflux pumps, (6) point mutation and overexpression of resistance genes, and (7) presence of persister cells. The genes involved and their implications in antimicrobial resistance are well defined for bacterial biofilms but are understudied in fungal biofilms. Potential therapeutics for biofilm mitigation that have been reported include (1) antimicrobial photodynamic therapy, (2) antimicrobial lock therapy, (3) antimicrobial peptides, (4) electrical methods, and (5) antimicrobial coatings. These approaches exhibit promising characteristics for addressing the impending crisis of antimicrobial resistance (AMR). Recently, advances in the micro- and nanotechnology field have propelled the development of novel biomaterials and approaches to combat biofilms either independently, in combination or as antimicrobial delivery systems. In this review, we will summarize the general principles of clinically important microbial biofilm formation with a focus on fungal biofilms. We will delve into the details of some novel micro- and nanotechnology approaches that have been developed to combat biofilms and the possibility of utilizing them in a clinical setting.

The present study focuses on the antimicrobial activity and safety aspect of lactobacilli strains isolated from the anogenital region. Sixty-two lactobacilli strains were isolated from 52 healthy, non-menstruating women from a local health clinic in Puchong, Selangor, Malaysia and confirmed by 16S rDNA sequencing. The samples were collected by sterile cotton swabs and directly streaked onto De Man, Rogosa, Sharpe agar prior to transportation to the lab on ice. A selective preliminary screening against several Candida albicans and Candida glabrata strains identified 5 promising lactobacilli strains for the subsequent assays; L. delbreuckii 45E, L. fermentum 28E, L. mucosae 28C, L. reuteri 29A and L. reuteri 29B. A follow-up antibacterial assay identified L. delbreuckii 45E, L. reuteri 29A and L. reuteri 29B as the lactobacilli strains with the highest inhibitory activity. Subsequent assays including haemolytic activity, susceptibility to antibiotics, quantification of D/l-lactic acid and H2O2 production as well as bile salt hydrolase (BSH activity) indicated that L. reuteri 29B was a promising probiotic candidate. An acute toxicity study in vivo involving the administration of 1 × 108, 1 × 109 and 1 × 1010 cfu/mouse/day demonstrated that L. reuteri 29B did not exert any adverse effects towards the mice which were evident through the absence of pathological changes in the histological examination and blood test. There was also a lack of bacterial translocation as confirmed by Random Amplified Polymorphic DNA (RAPD). The present study highlights the possibility of utilising L. reuteri 29B as a probiotic. It also demonstrates the possibility of isolating potential probiotics from the anogenital region.

No abstract

Candida-associated nosocomial infections are a persistent problem which has been steadily increasing over the years. The emergence of antimicrobial resistant strains has narrowed the spectrum of effective drugs that can be utilised and indicated the need for alternative therapeutics. Garlic is a spice often studied for its unique characteristics. Most of its antimicrobial properties have been attributed to the presence of allicin, which makes up more than 70% of thiosulfinates extracted from garlic. The present study aimed to determine the effects of fresh garlic extract (FGE) towards the expression of two major biofilm genes, Flo-8 and Ndt80 produced by C. albicans that enable the morphogenesis of yeast from planktonic cells to biofilm.  Minimum concentration required for FGE to inhibit C. albicans was determined through agar well and disc diffusion assay. Effect of FGE towards preformed C. albicans biofilms was evaluated at ¼× and ½× inhibitory concentrations of FGE and Amphotericin B, respectively by XTT assay. RNA from FGE-treated C. albicans was extracted, reverse transcribed and analysed by Real-Time Polymerase Chain Reaction (RT-PCR) to determine FGE effects towards the expression of Flo-8 and Ndt80. Inhibitory concentration of FGE was determined to be 100 mg/mL. Both genes appeared to be upregulated in the presence of FGE with a higher upregulation noted with Flo-8 (67.34 and 30.20-folds) when compared against Ndt80 (5.55 and 1.79-folds) at 5 mg/mL and 10 mg/mL, respectively. It is surmised that C. albicans upregulated these genes as a survival mechanism in the presence of FGE. The findings from this study indicate that FGE could inhibit C. albicans growth and biofilms. Further research is required to determine the minimum inhibitory concentration (MIC) through broth microdilution and to understand the mechanism behind this phenomenon before it can be utilised as a potential therapeutic to combat Candida-associated nosocomial infections.