Melanins are high molecular weight hydrophobic pigments that have been studied for their role in the virulence of fungal pathogens. We investigated t

Klebsiella pneumoniae (Kp), is a frequent cause of hospital and community-acquired infections and WHO had declared it as a “priority pathogen”. Biofilm is a major virulence factor of Kp and yet the mechanism of strong biofilm formation in Kp is unclear. A key objective of the present study is to investigate the differences between strong and weak biofilms formed by clinical isolates of Kp on various catheters and in different media conditions and to identify constituents contributing to strong biofilm formation. Quantification of matrix components (extracellular DNA (eDNA), protein, exopolysaccharides (EPS), and bacterial cells), confocal laser scanning microscopy (CLSM), field emission gun scanning electron microscopy (FEG-SEM) and flow-cytometry analysis were performed to compare strong and weak biofilm matrix. Our results suggest increased biofilm formation on latex catheters compared to silicone and silicone-coated latex catheters. Higher amounts of eDNA, protein, EPS, and dead cells were observed in the strong biofilm of Kp. High adhesion capacity and cell death seem to play a major role in formation of strong Kp biofilms. The enhanced eDNA, EPS, and protein in the biofilm matrix appear as a consequence of increased cell death.

Purpose.Fusarium,Aspergillus, and Dematiaceous are the most common fungal species causing keratitis in tropical countries. Herein we report a prospective study on fungal keratitis caused by these three fungal species.Methodology. A prospective investigation was undertaken to evaluate eyes with presumed fungal keratitis. All the fungal isolates (n=73) obtained from keratitis infections were identified using morphological and microscopic characters. Molecular identification using sequencing of the ITS region and antifungal susceptibility tests using microdilution method were done. The final clinical outcome was evaluated in terms of the time taken for resolution of keratitis and the final visual outcome. The results were analyzed after segregating the cases into three groups, namely,Fusarium,Aspergillus, and Dematiaceous keratitis.Results. Diagnosis of fungal keratitis was established in 73 (35.9%) cases out of 208 cases. The spectra of fungi isolated wereFusariumspp. (26.6%),Aspergillusspp. (21.6%), and Dematiaceous fungi (11.6%). The sequence of the ITS region could identify theFusariumandAspergillusspecies at the species complex level, and the Dematiaceous isolates were accurately identified. Using antifungal agents such as fluconazole, natamycin, amphotericin B, and itraconazole, the minimum inhibitory concentrations (MICs) forFusariumspp. were >32 μg/mL, 4–8 μg/mL, 0.5–1 μg/mL, and >32 μg/mL, respectively. Antifungal susceptibility data showed thatCurvulariaspp. was highly resistant to all the antifungal agents. Overall, natamycin and amphotericin B were found to be the most effective antifungal agents. The comparative clinical outcomes in all cases showed that the healing response in terms of visual acuity of the Dematiaceous group was significantly good when compared with theFusariumandAspergillusgroups (P<0.05). The time required for healing in theFusariumgroup was statistically significantly less when compared with theAspergillusand Dematiaceous groups.Conclusion. This study demonstrates important differences in microscopic features of scraping material and antifungal susceptibility between the three groups. Early and accurate identification coupled with the MIC data, and thereby appropriate treatment is crucial for complete recovery.

Persister cell (PC) is dormant, tolerant to antibiotics, and a transient reversible phenotype. These phenotypes are observed in P. aeruginosa and cause bacterial chronic infection as well as recurrence of biofilm-mediated infection. PC formation requires stringent response and toxin-antitoxin (TA) modules. This study shows the P. aeruginosa PC formation in planktonic and biofilm stages on ceftazidime, gentamicin, and ciprofloxacin treatments. The PC formation was studied using persister assay, flow cytometry using Redox Sensor Green, fluorescence as well as Confocal Laser Scanning Microscopy, and gene expression of stringent response and TA genes. In the planktonic stage, ceftazidime showed a high survival fraction, high redox activity, and elongation of cells was observed followed by ciprofloxacin and gentamicin treatment having redox activity and rod-shaped cells. The gene expression of stringent response and TA genes were upregulated on gentamicin followed by ceftazidime treatment and varied among the isolates. In the biofilm stage, gentamicin and ciprofloxacin showed the biphasic killing pattern, redox activity, gene expression level of stringent response and TA varied across the isolates. Ceftazidime treatment showed higher persister cells in planktonic growth while all three antibiotics were able to induce persister cell formation in the biofilm stage.

In the present study, biofilm formation was quantified in UTI isolates of Pseudomonas aeruginosa (n = 22) using the crystal violet assay and was categorized into; strong (n = 16), weak (n = 4), and moderate (n = 2) biofilm producers. Further experiments were done using strong (n = 4) and weak (n = 4) biofilm producers. Biofilm formation was greater in Luria broth followed by natural urine and artificial urine on silicone and silicone-coated latex. Cell adhesion and twitching motility were greater in strong biofilm producers. The presence of thick biofilm with an increased number of dead and total number of cells of strong biofilm producers was observed using CLSM. The concentrations of exopolymeric substances (eDNA, protein, and pel polysaccharide) were high in strong biofilm producers. FEG-SEM visualization of biofilm produced by strong biofilm producers showed more cells encased in thick biofilm matrix than weak ones. Overall results provide evidence for increased cell adhesion and twitching motility in strong biofilm producers.

To evaluate the level of superoxide dismutase (SOD) and SOD isoenzyme activity in lens epithelial cells (LECs) derived from different types of cataract in patients having phacoemulsification. Iladevi Cataract & IOL Research Centre, Memnagar, Ahmedabad, India. This observational study of 109 patients having phacoemulsification was performed to evaluate the level of activity in LECs of total superoxide dismutase (TSOD) and 2 superoxide dismutase isoenzymes: copper- (Cu) and zinc (Zn)-dependent SOD (Cu/Zn-SOD) and manganese (Mn)-dependent SOD (Mn-SOD). The curvilinear capsulorhexis (lens capsule) harboring LECs was obtained during phacoemulsification. The anterior lens capsule samples were processed for assaying SOD activity using the nitro blue tetrazolium reduction assay. The samples were grouped based on age and on pure cataract types. The highest level of TSOD, Cu/Zn-SOD, and Mn-SOD activity was in patients 50 years or younger. The activity declined gradually with age (P<.001). The level of TSOD activity increased in cortical cataract. The level of Cu/Zn-SOD and Mn-SOD isoenzyme activity in LECs was higher in cortical cataracts. A significant difference in the level of TSOD and Cu/Zn-SOD activity was found with different types of cataract (P<.001). The level of TSOD, Cu/Zn-SOD, and Mn SOD isoenzyme activity decreased with age in LECs of patients with age-related cataract. A significant difference in the level of TSOD and Cu/Zn-SOD isoenzyme activity between different types of cataract was observed. The activity of all 3 SOD isoenzymes was highest in cortical cataracts.