Optimized Silica-Binding Peptide-Mediated Delivery of Bactericidal Lysin Efficiently Prevents Staphylococcus aureus from Adhering to Device Surfaces.

Staphylococcal-associated device-related infections (DRIs) represent a significant clinical challenge causing major medical and economic sequelae. Bacterial colonization, proliferation, and biofilm formation after adherence to surfaces of the indwelling device are probably the primary cause of DRIs. To address this issue, we incorporated constructs of silica-binding peptide (SiBP) with ClyF, an anti-staphylococcal lysin, into functionalized coatings to impart bactericidal activity against planktonic and sessile Staphylococcus aureus. An optimized construct, SiBP1-ClyF, exhibited improved thermostability and staphylolytic activity compared to its parental lysin ClyF. SiBP1-ClyF-functionalized coatings were efficient in killing MRSA strain N315 (>99.999% within 1 h) and preventing the growth of static and dynamic S. aureus biofilms on various surfaces, including siliconized glass, silicone-coated latex catheter, and silicone catheter. Additionally, SiBP1-ClyF-immobilized surfaces supported normal attachment and growth of mammalian cells. Although the recycling potential and long-term stability of lysin-immobilized surfaces are still affected by the fragility of biological protein molecules, the present study provides a generic strategy for efficient delivery of bactericidal lysin to solid surfaces, which serves as a new approach to prevent the growth of antibiotic-resistant microorganisms on surfaces in hospital settings and could be adapted for other target pathogens as well.

Proteinuria in Severe Hypothyroidism: A Prospective Study.

CONTEXT: Hypothyroidism is associated with reversible decline in kidney function as measured by estimated glomerular filtration rate (eGFR). eGFR and proteinuria are the most important markers for clinical assessment of kidney function. Though hypothyroidism is associated with proteinuria in cross-sectional data, the impact of treatment on proteinuria is unknown. OBJECTIVE: This study explores the effect of thyroid hormone replacement therapy on eGFR and 24-hour urine protein excretion in patients with severe primary hypothyroidism. DESIGN AND PARTICIPANTS: This study was a prospective, observational cohort study in adults with severe primary hypothyroidism (serum thyrotropin [TSH] > 50 µIU/mL). Individuals with preexisting or past kidney disease, kidney or urinary tract abnormalities, calculi or surgery, diabetes mellitus, or hypertension were excluded. The participants received thyroid hormone replacement therapy. Thyroid functions, eGFR, 24-hour urine protein excretion, and biochemical parameters were measured at baseline and 3 months. SETTING: This study took place at a single center, a tertiary care referral and teaching hospital. RESULTS: Of 44 enrolled participants, 43 completed 3 months of follow-up. At 3 months, serum TSH levels decreased and thyroxine levels increased (P < .001 for both). Significant increases in eGFR (mean difference, 18.25 ± 19.49 mL/min/1.73 m2; 95% CI, 12.25 to 24.25, P < .001) and declines in 24-hour urine protein excretion (mean difference, -68.39 ± 125.89 mg/day; 95% CI, -107.14 to -29.65, P = .001) were observed. Serum cholesterol and low-density lipoprotein levels also significantly decreased (P < .001). CONCLUSIONS: Thyroid hormone replacement therapy in patients with severe primary hypothyroidism improves eGFR and decreases 24-hour urine protein excretion, thereby suggesting reversible alterations.

A Choline-Recognizing Monomeric Lysin, ClyJ-3m, Shows Elevated Activity against Streptococcus pneumoniae.

Streptococcus pneumoniae is a leading pathogen for bacterial pneumonia, which can be treated with bacteriophage lysins harboring a conserved choline binding module (CBM). Such lysins regularly function as choline-recognizing dimers. Previously, we reported a pneumococcus-specific lysin ClyJ comprising the binding domain from the putative endolysin gp20 from the Streptococcus phage SPSL1 and the CHAP (cysteine, histidine-dependent amidohydrolase/peptidase) catalytic domain from the PlyC lysin. A variant of ClyJ with a shortened linker, i.e., ClyJ-3, shows improved activity and reduced cytotoxicity. Resembling typical CBM-containing lysins, ClyJ-3 dimerized upon binding with choline. Herein, we further report a choline-recognizing variant of ClyJ-3, i.e., ClyJ-3m, constructed by deleting its C-terminal tail. Biochemical characterization showed that ClyJ-3m remains a monomer after it binds to choline yet exhibits improved bactericidal activity against multiple pneumococcal strains with different serotypes. In an S. pneumoniae-infected bacteremia model, a single intraperitoneal administration of 2.32 µg/mouse of ClyJ-3m showed 70% protection, while only 20% of mice survived in the group receiving an equal dose of ClyJ-3 (P < 0.05). A pharmacokinetic analysis following single intravenously doses of 0.29 and 1.16 mg/kg of ClyJ-3 or ClyJ-3m in BALB/c mice revealed that ClyJ-3m shows a similar half-life but less clearance and a greater area under curve than ClyJ-3. Taken together, the choline-recognizing monomer ClyJ-3m exhibited enhanced bactericidal activity and improved pharmacokinetic proprieties compared to those of its parental ClyJ-3 lysin. Our study also provides a new way for rational design and programmed engineering of lysins targeting S. pneumoniae.