launching at mmc - aspergillus galactomannan eia - “galactomannan screening for the early...
TRANSCRIPT
Launching at MMC - Aspergillus Galactomannan EIA -
“Galactomannan Screening for the Early Diagnosis of Invasive Aspergillosis”
Dr. Vilma M. Co / Dr. Demetrio Valle
• Pledge of Support – Pfizer / Lifeline
• Message of Acceptance – Makati Medical Center
• Ceremonial MOA Signing
...........................Refreshments……………………….
Aspergillus
• fungus (or mold) that is common in the environment – soil– plants and in decaying plant
matter– household dust– building materials– spices & some food items.
Different types of Aspergillus
• Aspergillus fumigatus
• Aspergillus flavus
• Aspergillus terreus
• Aspergillus nidulans
• Aspergillus niger
Aspergillosis
1. allergic bronchopulmonary aspergillosis (also called ABPA)
- a condition where the fungus causes allergic respiratory symptoms, such as wheezing and coughing, but does not actually invade and destroy tissue.
2. Invasive Aspergillosis
- a disease that usually affects people with immune system problems.
- the fungus invades and damages tissues in the body.
- most commonly affects the lungs, but can also cause infection in many other organs & can spread throughout the body.
Aspergillosis
High-risk Patients
• Invasive aspergillosis generally affects
immunocompromised patients– bone marrow transplant or solid organ transplant, – people who are taking high doses of corticosteroids, – people getting chemotherapy for cancers such as leukemia. – persons with advanced HIV infection
Mode of Transmission
• Inhalation of Aspergillus spores (i.e., in a very dusty environment) can lead to infection.
• Studies have shown that invasive aspergillosis can occur during building renovation or construction.
• Outbreaks of Aspergillus skin infections have been traced to contaminated biomedical devices.
Symptoms of Aspergillosis:
1. respiratory symptoms like wheezing, coughing and even fever
2. allergic sinusitis/bloody sputum
3. aspergilloma, or a “fungus ball” in the lung or other organs.
• Lung aspergillomas usually occur in people
with other forms of lung disease, like emphysema or a history of TB.
Invasive Aspergillosis
• fever, chest pain, cough, and shortness of breath.
• When invasive aspergillosis spreads outside of the lungs, it can affect almost any organ in the body, including the brain.
Diagnosis of Aspergillus infection
• risk factors, symptoms, & P.E. findings
• chest x-ray or CT scan of the lungs.
• fungal culture of samples of respiratory secretions or affected tissues
• biopsies of affected tissue
• newer tests that can help monitor for invasive aspergillosis in high-risk persons who are severely immunocompromised
Aspergillus Galactomannan EIA CLINICAL UTILITY
• used in conjunction with other diagnostic procedures to aid in the diagnosis of Invasive Aspergillosis. – microbiological culture – histological examination of biopsy specimens– radiographic evidence
Screening high-risk patients with PlateliaTM Aspergillus EIA, twice-weekly, provides early diagnosis of IA.
Recent publications: GM Ag was positive 6-10 days before onset of clinical signs GM positivity preceded positivity of CT-Scan or culture by >1 week PlateliaTM Aspergillus EIA was most sensitive (compared to RT-PCR and -glucan) at predicting the diagnosis of IA in patients with hematologic disorder.
Screening & Diagnosing IA in High-Risk Patients KEY BENEFITS :
Comparison to Other Diagnostic Methods :
Diagnostic Method Sensitivity SpecificityChest Radiograph 94% 60%
CT-Scan (any abnormality) 78% 7%
CT-Scan (halo sign) 28% 93%
Culture (BAL) 50% 92%
GM EIA :
Single sample 1.5
2 consecutive samples ≥ 1.5
94%
94%
85%
99%
J.Maertens JID 2002
Screening and Diagnosing IA in High-Risk patients
Treatment of Invasive Aspergillosis
• Voriconazole is currently first-line treatment for invasive aspergillosis.
• itraconazole, lipid amphotericin formulations, caspofungin, micafungin, and posaconazole
• Whenever possible, immunosuppressive medications should be discontinued or decreased.
Prevention
• avoidance of dusty environments and activities where dust exposure is likely (such as construction zones)
• wearing N95 masks in dusty environments • avoidance of activities such as gardening• air quality improvement measures such as HEPA
filtration may be used in healthcare settings• prophylactic antifungal medication in some
circumstances
PROCEDURE
• immunoenzymatic sandwich microplate assay for the detection of Aspergillus galactomannan antigen
• adult and pediatric serum samples
• uses EBA-2 monoclonal antibodies which detect Aspergillus galactomannan.
For maximum sensitivity, the test should be performed at least twice-weekly during hospitalization. For all positive patients, it is recommended that a new aliquot of the same sample be repeated as well as collection of a new sample from the patient.
According to the EORTC/MSG criteria, two consecutive positive results are required for classification as true positive. In daily practice, it is important that physicians submit a follow-up specimen upon receipt of the initial positive result, ideally before initiating antifungal therapy to achieve the highest specificity using the test.
Screening & Diagnosing IA in High-Risk patients
SPECIMEN TYPE & SPECIMEN HANDLING
• Serum: • Collect 3 to 5 ml blood specimen in a serum
separator tube (SST) without anti-coagulants. • Allow specimen to clot, then centrifuge specimen
within 2 hours of draw to pellet cells below the gel. • Minimum volume of 1.0 ml serum following
centrifugation is required. • Specimen should be stored at 2 to 8°C or frozen in
a non-self-defrosting freezer & shipped with frozen gel packs or dry ice for overnight delivery
• BAL:
• 1 to 3 ml collected in a sterile, screw-cap tube;
• specimen should be stored at 2 to 8°C or frozen in a non-self-defrosting freezer
• shipped with frozen gel packs or dry ice for overnight delivery
SPECIMEN TYPE & SPECIMEN HANDLING
CAUSES FOR REJECTION of specimen
• Lipemic, icteric, or hemolyzed specimens.
• Specimens that have been stored at ambient temperature.
• Specimens that have been stored at 2 to 8°C for >5 days.
• If storage longer than 5 days is needed, samples should be frozen at -70°C.
ASSAY RANGE
• The reference range is an index of <0.5.• Numerical index values will be reported. • Patients with an index of >0.5 are
considered to be positive for galactomannan antigen.
• Patients with an index of <0.5 are considered to be negative for galactomannan antigen.
ASSAY LIMITATIONS
• A negative test result cannot rule out the diagnosis of Invasive Aspergillosis.
• Patients at risk for Invasive Aspergillosis should be tested twice per week.
• If a positive result is obtained, a second specimen should be collected and sent for testing immediately.
False-positive galactomannan test results
• patients receiving piperacillin/tazobactam; interpret results in these patients with caution & confirm w/ other diagnostic methods.
• Patients with intestinal mucositis caused by chemotherapy / irradiation, which allows for extra absorption of dietary galactomannan.
• patients receiving Plasmalyte for IV hydration or if Plasmalyte is used for BAL collection.