Unveiling antibiofilm potential: proteins from Priestia sp. targeting Staphylococcus aureus biofilm formation.

Staphylococcus aureus is the etiologic agent of many nosocomial infections, and its biofilm is frequently isolated from medical devices. Moreover, the dissemination of multidrug-resistant (MDR) strains from this pathogen, such as methicillin-resistant S. aureus (MRSA) strains, is a worldwide public health issue. The inhibition of biofilm formation can be used as a strategy to weaken bacterial resistance. Taking that into account, we analysed the ability of marine sponge-associated bacteria to produce antibiofilm molecules, and we found that marine Priestia sp., isolated from marine sponge Scopalina sp. collected on the Brazilian coast, secretes proteins that impair biofilm development from S. aureus. Partially purified proteins (PPP) secreted after 24 hours of bacterial growth promoted a 92% biofilm mass reduction and 4.0 µg/dL was the minimum concentration to significantly inhibit biofilm formation. This reduction was visually confirmed by light microscopy and Scanning Electron Microscopy (SEM). Furthermore, biochemical assays showed that the antibiofilm activity of PPP was reduced by ethylenediaminetetraacetic acid (EDTA) and 1,10 phenanthroline (PHEN), while it was stimulated by zinc ions, suggesting an active metallopeptidase in PPP. This result agrees with mass spectrometry (MS) identification, which indicated the presence of a metallopeptidase from the M28 family. Additionally, whole-genome sequencing analysis of Priestia sp. shows that gene ywad, a metallopeptidase-encoding gene, was present. Therefore, the results presented herein indicate that PPP secreted by the marine Priestia sp. can be explored as a potential antibiofilm agent and help to treat chronic infections.

N4 -benzyl-N2 -phenylquinazoline-2,4-diamine compound presents antibacterial and antibiofilm effect against Staphylococcus aureus and Staphylococcus epidermidis.

Staphylococcus aureus and Staphylococcus epidermidis are the main agents involved with implant-related infections. Their ability to adhere to medical devices with subsequent biofilm formation is crucial to the development of these infections. Herein, we described the antibacterial and antibiofilm activities of a quinazoline-based compound, N4 -benzyl-N2 -phenylquinazoline-2,4-diamine, against both biofilm-forming pathogens. The minimum inhibitory concentrations (MIC) were determined as 25 µM for S. aureus and 15 µM for S. epidermidis. At sub-MIC concentrations (20 µM for S. aureus and 10 µM for S. epidermidis), the compound was able to inhibit biofilm formation without interfere with bacterial growth, confirmed by scanning electron microscopy. Moreover, surfaces coated with the quinazoline-based compound were able to prevent bacterial adherence. In addition, this compound presented no toxicity to human red blood cells at highest MIC 25 µM and in vivo toxicity assay using Galleria mellonella larvae resulted in 82% survival with a high dose of 500 mg/kg body weight. These features evidence quinazoline-based compound as interesting entities to promising applications in biomedical fields, such as antimicrobial and in anti-infective approaches.

Alterations of zinc homeostasis in response to Cryptococcus neoformans in a murine macrophage cell line.

AIM: To evaluate alterations of zinc homeostasis in macrophages exposed to Cryptococcus neoformans. Materials & methods: Using a fluorescent zinc probe-based flow cytometry and atomic absorption spectrometry, zinc levels were evaluated in J774.A1 cell lines exposed to C. neoformans H99 cells. The transcription profile of macrophage zinc related homeostasis genes - metallothioneins and zinc transporters (ZnTs) of the SLC30 and SLC39 (Zrt-Irt-protein) families - was analyzed by quantitative PCR. RESULTS: Macrophage intracellular labile zinc levels decreased following exposure to C. neoformans. A significant decrease in transcription levels was detected in specific ZnTs from both the Zrt-Irt-protein and ZnT families, especially 24 h after infection. CONCLUSION: These findings suggest that macrophages may exhibit zinc depletion in response to C. neoformans infection.