Effects of lipid emulsions on the formation of Escherichia coli-Candida albicans mixed-species biofilms on PVC.

Patients receiving lipid emulsions are at increased risk of contracting catheter-related bloodstream infections (CRBSIs) in the clinic. More than 15% of CRBSIs are polymicrobial. The objective of this study was to explore the effects of lipid emulsions on the formation of Escherichia coli (E. coli)-Candida albicans (C. albicans) mixed-species biofilms (BFs) on polyvinyl chloride (PVC) surfaces and the underlying mechanism. Mixed-species BFs were produced by coculturing E. coli and C. albicans with PVC in various concentrations of lipid emulsions. Crystal violet staining and XTT assays were performed to test the mixed-species BF biomass and the viability of microbes in the BFs. The microstructures of the BFs were observed by an approach that combined confocal laser scanning microscopy, fluorescence in situ hybridization, and scanning electron microscopy. The study found that lipid emulsions could promote the formation of E. coli-C. albicans mixed-species BFs, especially with 10% lipid emulsions. The mechanism by which lipid emulsions promote mixed-species BF formation may involve significant upregulation of the expression of the flhDC, iha, HTA1, and HWP1 genes, which are associated with bacterial motility, adhesion, and BF formation. The results derived from this study necessitate strict aseptic precautions when handling lipid emulsions and avoiding the use of high concentrations of lipid emulsions for as long as possible.

Antibiotic-induced black hairy tongue: two case reports and a review of the literature.

Black hairy tongue (BHT) is characterized by a discolored, hairy tongue. We herein report two cases of BHT associated with antibacterial agents and review previous cases. In Case 1, a 17-year-old girl with a central neurocytoma was administered intravenous piperacillin-tazobactam for postoperative infection, and BHT developed 12 days later. Her symptoms resolved 8 days after she discontinued the piperacillin-tazobactam and brushed her tongue three times daily. In Case 2, a 65-year-old man was administered intravenous piperacillin-tazobactam and levofloxacin to treat multidrug-resistant Pseudomonas aeruginosa, and BHT developed 15 days later. The piperacillin-tazobactam was discontinued and the patient brushed his tongue, and the discoloration gradually subsided thereafter. However, the BHT reappeared after linezolid treatment. The patient had adverse drug reactions to both the piperacillin-tazobactam and linezolid treatments. The BHT might have been related to antibiotic use in both cases. We identified 19 cases of antibiotic-related BHT in a literature search, but none were related to piperacillin-tazobactam use. In all cases, symptoms resolved after discontinuation of the drug and brushing of the tongue. BHT may be a rare adverse effect of antibiotics. Treatment strategies include removal of the causative agents, mechanical debridement, and good oral hygiene.

Study on the Structure of Candida Albicans-Staphylococcus Epidermidis Mixed Species Biofilm on Polyvinyl Chloride Biomaterial.

The objective of the study was to establish an in vitro model of Candida albicans-Staphylococcus epidermidis mixed species biofilm (BF) on polyvinyl chloride (PVC) material, and to investigate the formation and the structure of mixed species BF formation using a combined approach of confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), and 3D image reconstruction technique. Mixed species BF is achieved by co-incubating Staphylococcus epidermidis bacteria (ATCC35984) and Candida albicans fungal (ATCC10231) with PVC pieces in Tris-buffered saline. BF formation was examined at 2, 6, 12, 24, 48, and 72 h of co-culture. Thickness of these BFs and the number, and percentage of viable cells in BFs were measured. CT scan images of BFs were obtained using CLSM and SEM and reconstructed 3D images of mixed species BF were acquired, in an effort to examine structure of the BF. Staphylococcus epidermidis attached to various forms of candida albicans (spores, pseudohyphae, and hyphae), formed complex and dense mesh arrays. The BF is constituted of a large number of viable and dead pathogens, the surface of mixed species BF is uneven, with living pathogens predominating protrusive portions and dead pathogens aggregating in concaves. Mixed species BF formation on the surface of PVC material was found to be a dynamic process, with rapid growth being at 24 h of co-culture, maximal thickness peaked at 48 h. These mixed species BF matured at 48-72 h. Significant differences were observed in the proportion of viable cells between interior, middle, and outer layers of BFs (p < 0.05). Mixed species BF Candida albicans-Staphylococcus epidermidis is sophisticated in structure. The combined approach involving CLSM, SEM, and 3D image reconstruction technique is ideal for the investigation of mixed species BF on PVC material.