System for determining peritonitis using homodimer neutrophil gelatinase-associated lipocalin

An assay kit comprising:

• a binding molecule that, within a context of the assay kit, specifically binds to neutrophil gelatinase-associated lipocalin (NGAL) homodimer (H-NGAL), but not to a monomer or a heterodimer of NGAL;
• a binding molecule that specifically binds an antigen indicative of a presence of a gram-positive bacteria;
• and
• a binding molecule that specifically binds an antigen indicative of the presence of gram-negative bacteria.

A method of diagnosing peritonitis in a subject who is a peritoneal dialysis patient, the method comprising:

• detecting in a peritoneal dialysis effluent (PDE) from the subject an antigen indicative of a presence of a microorganism selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungus, and any combination thereof;
• and
• detecting in the peritoneal dialysis effluent neutrophil gelatinase-associated lipocalin (NGAL) homodimer (H-NGAL);
• wherein detecting in a peritoneal dialysis effluent from the subject comprises contacting the H-NGAL with a first molecule that specifically binds to H-NGAL, but wherein the first molecule does not bind to a monomer or a heterodimer of NGAL.

A method of treating a peritoneal dialysis patient suspected as having peritonitis, the method comprising:

• detecting in a peritoneal dialysis effluent (PDE) from the patient at least one antigen indicative of a presence of a microorganism selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungus, and any combination thereof;
• detecting in the peritoneal dialysis effluent neutrophil gelatinase-associated lipocalin (NGAL) homodimer (H-NGAL);
• and
• administering a selected antibiotic to the patient, wherein an appropriate antibiotic is selected based upon results of the detection of particular antigen(s) in the PDE,
• wherein an amount of H-NGAL is greater than or equal to a cut-off value of H-NGAL in the PDE.

A strip for diagnosing peritonitis, the strip comprising:

• a solid support comprising a sample pad, the sample pad configured to receive a sample from a patient, the sample being a peritoneal dialysis effluent (PDE);
• a conjugate pad adjacent to the sample pad, wherein the conjugate pad comprises a first molecule that specifically binds to neutrophil gelatinase-associated lipocalin homodimer (H-NGAL), but not to a monomer or heterodimer of NGAL;
• and
• a nitrocellulose membrane, the nitrocellulose membrane comprising a control line and a test line.

A method of diagnosing an infection in a subject, the method comprising:

• interacting peritoneal dialysis effluent (PDE) taken from a subject with an assay kit comprising:
• at least one first binding molecule that specifically binds neutrophil gelatinase-associated lipocalin (NGAL), and
• at least one second binding molecule that specifically binds NGAL homodimer (H-NGAL), but does not bind a monomer of NGAL or a heterodimer of NGAL,
• wherein the first binding molecule, the second binding molecule, or both the first and second binding molecule are conjugated with a label;
• and
• detecting a presence of H-NGAL in the PDE with aid of the label so as to determine that the subject is suffering from an infection.

A method of treating peritonitis in a peritoneal dialysis subject, comprising:

• detecting neutrophil gelatinase-associated lipocalin homodimer (H-NGAL) protein in a peritoneal dialysis effluent of a subject;
• determining a level of H-NGAL;
• comparing the level of H-NGAL against a cutoff value;
• and
• administering an antibiotic therapy if the level of H-NGAL exceeds the cutoff value.