Guidance for Industry  
and FDA Staff 
 
Class II Special Controls Guidance 
Document: Serological Assays for 
the Detection of Beta-Glucan  
 
 
Document issued on: September 23, 2004
 
 
 
For questions regarding this document contact Freddie M. Poole at 301-594-2096 ext. 111 or by 
email at fmp@cdrh.fda.gov. 
 
 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Devices and Radiological Health 
 
 
Division of Microbiology Devices  
Office of In Vitro Diagnostic Device Evaluation and Safety  Contains Nonbinding Recommendations 
 
Preface 
 
Public Comment 
 
Written comments and suggestions may be submitted at any time for Agency consideration to 
Division of Dockets Management, Food and Drug Administration, 5630 Fishers Lane, Room 
1061, (HFA-305), Rockville, MD, 20852.  Alternatively, electronic comments may be 
submitted to http://www.fda.gov/dockets/ecomments.  When submitting comments, please 
refer to Docket No. 2004D-0371. Comments may not be acted upon by the Agency until the 
document is next revised or updated. 
 
Additional Copies 
 
Additional copies are available from the Internet at: 
http://www.fda.gov/cdrh/oivd/guidance/1825.pdf, or to receive this document via your fax 
machine, call the CDRH Facts-On-Demand system at 800-899-0381 or 301-827-0111 from a 
touch-tone telephone.  Press 1 to enter the system.  At the second voice prompt, press 1 to 
order a document.  Enter the document number (1825) followed by the pound sign (#).  
Follow the remaining voice prompts to complete your request.  For questions regarding the 
use or interpretation of this guidance contact: Freddie M. Poole at (301) 594-2096 ext. 111 or 
by email at fmp@cdrh.fda.gov. 
 
 
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Table of Contents 
 
1.  INTRODUCTION..................................................................................................................4 
2.  BACKGROUND.....................................................................................................................5 
3.  THE CONTENT AND FORMAT OF AN ABBREVIATED 510(K) SUBMISSION......6 
4.  SCOPE.....................................................................................................................................8 
5.  RISKS TO HEALTH.............................................................................................................8 
6.  PERFORMANCE CHARACTERISTICS...........................................................................8 
7.  METHOD COMPARISON.................................................................................................11 
8.  LABELING...........................................................................................................................12 
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Guidance for Industry and FDA Staff  
 
Class II Special Controls Guidance 
Document: Serological Assays for the 
Detection of Beta-Glucan 
 
This guidance represents the Food and Drug Administration's (FDA's) current thinking on 
this topic.  It does not create or confer any rights for or on any person and does not operate to 
bind FDA or the public.  You can use an alternative approach if the approach satisfies the 
requirements of the applicable statutes and regulations. If you want to discuss an alternative 
approach, contact the FDA staff responsible for implementing this guidance.  If you cannot 
identify the appropriate FDA staff, call the appropriate number listed on the title page of this 
guidance.  
 
1.  Introduction 
This guidance document was developed as a special controls guidance to support the 
classification of beta-glucan serological assays into class II (special controls).  Beta-glucan 
serological assays are devices consisting of antigens or proteases that aid in the presumptive 
diagnosis of fungal infection.  The devices are intended for the qualitative detection of beta-
glucan in the serum of patients with symptoms of, or medical conditions predisposing the patient 
to, invasive fungal infection.  The detection in serum of specified concentrations of beta-glucan, 
a major cell-wall component of various medically important fungi, can be used as an aid in the 
diagnosis of deep-seated mycoses and fungemias.  The assays should be used in conjunction with 
other diagnostic procedures, such as microbiological culture, histological examination of biopsy 
samples, and radiological examination. 
 
This guidance is issued in conjunction with a Federal Register notice announcing the 
classification of beta-glucan serological assays.1  Any firm submitting a premarket notification 
(510(k)) for beta-glucan serological assays will need to address the issues covered in this special 
controls guidance document.  However, the firm need only show that its device meets the 
recommendations of the guidance or in some other way provides equivalent assurances of safety 
and effectiveness. 
 
FDA's guidance documents, including this guidance, do not establish legally enforceable 
responsibilities.  Instead, guidance documents describe the Agency's current thinking on a topic 
and should be viewed only as recommendations, unless specific regulatory or statutory 
                                                           
1 Unlike the other classification regulations in 21 CFR part 866, subpart D, which use the term 
reagents in their titles, FDA is using assays to refer to this device type because this term 
more accurately reflects the devices within this type. 
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requirements are cited.  The use of the word should in Agency guidance documents means that 
something is suggested or recommended, but not required. 
 
The Least Burdensome Approach 
The issues identified in this guidance document represent those that we believe need to be 
addressed before your device can be marketed.  In developing the guidance, we carefully 
considered the relevant statutory criteria for Agency decision-making.  We also considered the 
burden that may be incurred in your attempt to follow the statutory and regulatory criteria in the 
manner suggested by the guidance and in your attempt to address the issues we have identified.  
We believe that we have considered the least burdensome approach to resolving the issues 
presented in the guidance document.  If, however, you believe that there is a less burdensome 
way to address the issues, you should follow the procedures outlined in the document, A 
Suggested Approach to Resolving Least Burdensome Issues.  It is available on our Center web 
page at: http://www.fda.gov/cdrh/modact/leastburdensome.html. 
 
2.  Background 
FDA believes that special controls, when combined with the general controls, will be 
sufficient to provide reasonable assurance of the safety and effectiveness of a beta-glucan 
assay.  A manufacturer who intends to market a device of this generic type should (1) 
conform to the general controls of the Federal Food, Drug, and Cosmetic Act (the Act), 
including the premarket notification requirements described in 21 CFR 807 Subpart E, (2) 
address the specific risks to health associated with the beta-glucan serological assay 
identified in this guidance, and (3) obtain a substantial equivalence determination from FDA 
before marketing the device. 
 
This guidance document identifies the classification regulation and product code for beta-glucan 
serological assays. (Refer to Section 4  Scope.)  In addition, other sections of this guidance 
document identify the risks to health and describe measures that, if followed by manufacturers 
and combined with the general controls, will generally address the risks associated with these 
beta-glucan serological assays and lead to a timely premarket notification [510(k)] review and 
clearance.  This document supplements other FDA documents regarding the specific content 
requirements of a premarket notification submission.  You should also refer to 21 CFR 807.87 
and other FDA documents on this topic, such as the 510(k) Manual - Premarket Notification: 
510(k) - Regulatory Requirements for Medical Devices, 
http://www.fda.gov/cdrh/manual/510kprt1.html. 
 
As explained in The New 510(k) Paradigm - Alternate Approaches to Demonstrating 
Substantial Equivalence in Premarket Notifications; Final Guidance2, a manufacturer may 
submit either a Traditional 510(k) or an Abbreviated 510(k).  FDA believes an Abbreviated 
510(k) provides the least burdensome means of demonstrating substantial equivalence for a new 
device, particularly when FDA has issued a guidance document that provides recommendations 
on what should be addressed in a submission for the device.   Alternatively, manufacturers 
                                                           
2 http://www.fda.gov/cdrh/ode/parad510.html 
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considering modifications to their own cleared devices may lessen the regulatory burden by 
submitting a Special 510(k). 
 
3.  The Content and Format of an Abbreviated 510(k) 
Submission  
An Abbreviated 510(k) submission must include the required elements identified in 21 CFR 
807.87, including the proposed labeling for the device sufficient to describe the device, its 
intended use, and the directions for its use.  In an Abbreviated 510(k), FDA may consider the 
contents of a summary report to be appropriate supporting data within the meaning of 21 CFR 
807.87(f) or (g); therefore, we recommend that you include a summary report.  The report should 
describe how this guidance document was used during the device development and testing and 
the methods or tests used.  The report should also include a summary of the test data or 
description of the acceptance criteria applied to address the risks identified in this document, as 
well as any additional risks specific to your device.  This section suggests information to fulfill 
some of the requirements of 21 CFR 807.87 as well as some other items that we recommend you 
include in an Abbreviated 510(k). 
 
Coversheet 
The coversheet should prominently identify the submission as an Abbreviated 510(k) and 
cite the title of this guidance document. 
 
Proposed labeling 
Proposed labeling should be sufficient to describe the device, its intended use, and the 
directions for its use.  (Refer to Section 8 for specific information that you should include in 
the labeling for this type of device.) 
 
Summary report 
We recommend that the summary report contain the following: 
 
  A description of the device and its intended use.  We recommend that the description 
include a complete discussion of the performance specifications and, when 
appropriate, detailed, labeled drawings of the device.  You should also submit an 
"indications for use" enclosure.3   
 
  A description of the device design.  
 
  Identification of the Risk Analysis method(s) used to assess the risk profile in 
general, as well as the specific devices design and the results of this analysis.  (Refer 
to Section 5 for the risks to health generally associated with the use of this device.) 
 
                                                           
3 Refer to http://www.fda.gov/cdrh/ode/indicate.html for the recommended format. 
 
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  A discussion of the device characteristics that address the risks identified in this class 
II guidance document, as well as any additional risks identified in your risk analysis.  
 
  A brief description of the test method(s) you have used or intend to use to address 
each performance aspect identified in Sections 6 and 7 of this guidance document.  If 
you follow a suggested test method, you may cite the method rather than describing 
it.  If you modify a suggested test method, you may cite the method, but should 
provide sufficient information to explain the nature of and reason for the 
modification.  For each test, you may either (1) briefly present the data resulting from 
the test in clear and concise form, such as a table, or (2) describe the acceptance 
criteria that you will apply to your test results.4  (See also 21 CFR 820.30, Subpart C - 
Design Controls for the Quality System Regulation.) 
 
  If any part of the device design or testing relies on a recognized standard, (1) a 
statement that testing will be conducted and meet specified acceptance criteria before 
the product is marketed, or (2) a declaration of conformity to the standard.5  Please 
note that testing must be completed before submitting a declaration of conformity to a 
recognized standard.  (Section 514(c)(1)(B) of the Act.)  For more information refer 
to the FDA guidance, Use of Standards in Substantial Equivalence 
Determinations; Final Guidance for Industry and FDA, 
http://www.fda.gov/cdrh/ode/guidance/1131.html.  
 
If it is not clear how you have addressed the risks identified by FDA or additional risks identified 
through your risk analysis, we may request additional information about aspects of the devices 
performance characteristics.  We may also request additional information if we need it to assess 
the adequacy of your acceptance criteria.  (Under 21 CFR 807.87(l), we may request any 
additional information that is necessary to reach a determination regarding substantial 
equivalence.)  
 
As an alternative to submitting an Abbreviated 510(k), you can submit a Traditional 510(k) that 
provides all of the information and data required under 21 CFR 807.87 and described in this 
guidance.  A Traditional 510(k) should include all of your methods, data, acceptance criteria, and 
conclusions.  Manufacturers considering modifications to their own cleared devices should 
consider submitting Special 510(k)s.  
 
                                                           
4 If FDA makes a substantial equivalence determination based on acceptance criteria, the subject 
device should be tested and shown to meet these acceptance criteria before being introduced into 
interstate commerce.  If the finished device does not meet the acceptance criteria and, thus, 
differs from the device described in the cleared 510(k), FDA recommends that submitters apply 
the same criteria used to assess modifications to legally marketed devices (21 CFR 807.81(a)(3)) 
to determine whether marketing of the finished device requires clearance of a new 510(k). 
 
5 See Required Elements for a Declaration of Conformity to a Recognized Standard (Screening 
Checklist for All Premarket Notification [510(K)] Submissions), 
http://www.fda.gov/cdrh/ode/reqrecstand.html. 
 
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4.  Scope 
The scope of this document is limited to the following devices as described in 21 CFR 866.3050 
(product code NQZ): 
 
21 CFR 866.3050  Beta-glucan serological assays 
Beta-glucan serological assays are devices that consist of antigens or proteases used in 
serological assays.  The device is intended for use for the presumptive diagnosis of fungal 
infection.  The assay is indicated for use in patients with symptoms of, or medical conditions 
predisposing the patient to, invasive fungal infection.  The device can be used as an aid in the 
diagnosis of deep seated mycoses and fungemias.  
 
5.  Risks to Health 
There are no known direct risks to patient health.  However, failure of the test to perform as 
indicated or error in interpretation of results may lead to improper patient management, which 
includes misdiagnosis and improper treatment. Therefore, use of assay results to adjust a 
treatment regimen, without considerations of other clinical factors, could pose a risk.  A falsely 
low beta-glucan measurement, or false negative result, could result in a determination that the 
patient is not at risk for invasive fungal infection and could delay appropriate treatment.   A 
falsely high measurement, or false positive, could contribute to unnecessary monitoring or 
potentially toxic therapy.   
 
In the table below, FDA has identified the risk to health generally associated with the use of a 
beta-glucan serological assay addressed in this document.  The measures recommended to 
mitigate the identified risk are described in this guidance document, as shown in the table below.  
You should conduct a risk analysis, prior to submitting your premarket notification, to identify 
any other risks specific to your device.  The premarket notification should describe the risk 
analysis method.  If you elect to use an alternative approach to address the risk identified in this 
document, or have identified risks additional to those in this document, you should provide 
sufficient detail to support the approach you have used to address that risk. 
 
Identified risk  Recommended mitigation measures 
Improper Patient Management  Sections 6, 7, and 8 
 
6.  Performance Characteristics 
 
General Study Recommendations 
 
We recommend that you include in the 510(k) a description of the method used to detect beta-
glucan.  You should also include a description of the reagent components in the kit.  We 
recommend that whenever possible, you include patient samples derived from the intended use 
population (e.g. critically ill patients) for the analytical protocols described below.   
 
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We recommend that you evaluate the assay in at least two external sites in addition to that of the 
manufacturer.  Generally, we recommend that performance be assessed in the testing 
environment where the device will ultimately be used (i.e., central laboratory or point of care, 
such as an intensive care unit (ICU)) by individuals who will use the test in clinical practice 
(e.g., trained technologists).  We recommend that you initially analyze data separately to 
evaluate any inter-site variation and include results of the analysis in the 510(k) summary report.  
You can pool clinical study results from the individual sites in the package insert if you 
demonstrate that there are no significant differences in the populations tested and the results 
among sites.  You may contact the Division of Microbiology Devices to discuss questions you 
have about a clinical study or other issues. 
 
We recommend that you provide appropriate specifics concerning protocols, so that acceptance 
criteria or data summaries can be best interpreted during the review. For example, when referring 
to National Committee for Clinical Laboratory Standards (NCCLS) protocols or guidelines, we 
recommend that you indicate which specific aspects of the protocols or guidelines you followed. 
  
Specific Performance Characteristics 
  
Precision and Reproducibility  
We recommend that you characterize within-run and total precision using serum samples 
according to guidelines provided in Evaluation of Precision Performance of Clinical 
Chemistry Devices; Approved Guideline (1999) NCCLS, Document EP5-A.  That 
document includes guidelines for experimental design, computations, and a format for stating 
performance claims.  We recommend that you evaluate precision at relevant beta-glucan 
concentrations, including near medical decision points and concentrations near the limits of 
the reportable range. 
We recommend that you include in the 510(k) the following items: 
  point estimates of the concentration 
  standard deviations of within-run and total precision 
  sites at which precision protocol was run 
  number of days, runs, and observations 
  number of sites and/or operators 
We recommend that you identify which factors (e.g., instrument calibration, reagent lots, 
operators) were held constant and which were varied during the evaluation. You should 
describe the computational methods, if they are different from that described in NCCLS EP5-
A.  
Interference 
We recommend that you characterize the effects of potential interferents on assay 
performance. Examples of experimental designs, including guidelines for selecting 
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interferents for testing, are described in detail in Interference Testing in Clinical Chemistry; 
Approved Guideline (2002) NCCLS, Document EP7-A. 
 
Potential sources of interference can include compounds normally found in serum such as 
triglycerides, hemoglobin, and bilirubin.  Typically, interference studies involve adding the 
potential interferent to the serum sample and determining any bias in the recovery of beta-
glucan relative to a control sample (to which no interferent has been added).   
 
We recommend that you include the following items in your 510(k): 
 
  types and levels of interferents tested 
  beta-glucan level in the samples 
  number of replicates tested 
  definition or method of computing interference 
We recommend that you identify any observed trends in bias (i.e., negative or positive) and 
indicate the range of observed recoveries in the presence of the particular interferent.  This 
approach is more informative than listing average recoveries alone.  We recommend that you 
state the criteria on which non-interference is determined.   
 
You may not need to perform additional interference testing with potential interferents 
already identified in literature or by other sources. However, we recommend that you 
identify these potential interferents in the labeling.   
 
Cross reactivity 
 
We recommend that you include data in your 510(k) on the assay specificity by measuring 
the cross reactivity of your device with other bacterial and fungal cell wall components, such 
as:  lipopolysaccharide (LPS) from gram negative bacteria, lipoteichoic acid (LTA) from 
gram positive bacteria, yeast mannan, and yeast cell wall extracts and galactomannan.  We 
recommend that you describe the purity of the components used to evaluate cross reactivity. 
 
Linearity 
We recommend that you characterize the linear range of the assay by evaluating samples 
whose concentration levels are known relative to each other.  Evaluation of the Linearity of 
Quantitative Analytical Methods, Approved Guideline (2003) NCCLS Document EP6-A 
describes a protocol for sample preparation and value assignment, as well as a format for 
stating performance characteristics.   
We recommend that you describe the sample types and preparation, concentrations, and 
number of replicates.  When describing your acceptance criteria or summary data, we 
recommend that you include the slope, intercept, and confidence intervals of the 
estimated line, and the range of linearity and the degree of deviations (biases) from the 
estimated line that were observed or that are considered acceptable for the various 
concentration levels.  Often these deviations can be best described by listing observed or 
acceptable values relative to the expected values for each level evaluated. 
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Analytical Sensitivity 
We recommend that you calculate the analytical sensitivity of the assay.  Often this is 
defined as the lowest level of beta-glucan that can be reliably measured by the test. 
 
We recommend that you describe the sample type you used in the evaluation.  You should 
define your measure of analytical sensitivity and provide your acceptance criteria or a data 
summary.  We recommend that you clarify how measurements below the level of sensitivity 
are reported to the user. 
 
Specimen collection and handling conditions 
We recommend that you substantiate statements in your labeling about specimen storage and 
transport by assessing whether the device can maintain acceptable performance (e.g., 
precision) over the storage times and temperatures recommended to users. For example, an 
appropriate study may include an analysis of aliquots stored under the conditions of time, 
temperature, or specified number of freeze/thaw cycles. We recommend that you state the 
criteria for an acceptable range of recoveries under the recommended storage and handling 
conditions. 
   
7. Method Comparison  
 
Clinical Sensitivity 
 
We recommend that you compare your assay to clinical diagnoses of invasive mycoses and 
fungemias that were obtained by observing clinical signs and symptoms and use of other 
diagnostic methods consistent with accepted medical practices.  It would be appropriate to 
refer to guidelines from the Invasive Fungal Infection Cooperative Group (IFICG) of the 
European Organization for Research and Treatment of Cancer (EORTC) and the Mycosis 
Study Group (MSG) of the National Institute of Allergy and Infectious Diseases (NIAID), 
which describe the criteria for proven, probable and possible invasive fungal disease.  Your 
study population should include proven positives and high risk subjects based on clinical 
signs and symptoms for fungal infection (i.e. patients who are neutropenic, febrile, or 
unresponsive to broad spectrum antibiotics, due to underlying conditions such as 
hematological malignancies, transplants, or surgical intensive care).  As with studies to 
evaluate performance characteristics, you may contact the Division of Microbiology Devices 
for input on your study plan prior to initiating clinical studies.  
 
Clinical Specificity 
 
We recommend that you evaluate the clinical specificity of your beta-glucan serological 
assay in hospitalized patients who are not critically ill, but who have similar signs and 
symptoms of invasive fungemias and mycoses.  We prefer that you include patients admitted 
to hospitals for reasons other than fungal infections. 
 
Sample selection, inclusion, and exclusion criteria 
 
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We recommend that you evaluate patient samples with beta-glucan concentrations distributed 
across the reportable range of the assay.  We suggest that you provide a clear description of 
how the samples were selected, including reasons that samples are excluded. We recommend 
that you include patients from the target population (i.e., serum samples from critically ill 
patients).  
 
Appropriate sample size depends on factors such as variability of the samples and standard 
deviation of the test results.  We recommend that you provide the statistical method used to 
determine the study sample size.  
 
Expected Values 
 
We recommend that you evaluate asymptomatic patients to determine the presence of beta-
glucan in a healthy population.  We also suggest that you collect data from other hospitalized 
patients who are critically ill but who are not considered at risk for invasive fungemia and 
mycoses.  We prefer that you select control groups whose age and gender distribution are 
similar to the patients selected for the sensitivity study in order to minimize sample 
variability and bias in the assay results. 
 
Presentation of results 
 
When providing the results of your study we recommend that you compare beta-glucan 
serological assay results obtained with your device to standard methods of detection (i.e. 
blood culture, histopathological examination of biopsy specimens and radiological signs for 
the clinical diagnosis of mycoses and fungemias).  We recommend that you stratify data and 
analyze by clinical status (e.g. proven infection, probable infection and healthy individuals) 
and by risk group (high or low risk of fungal infection) if these factors have the potential to 
bias the results. 
 
8.  Labeling  
The premarket notification should include labeling in sufficient detail to satisfy the requirements 
of 21 CFR 807.87(e).  The following suggestions are aimed at assisting you in preparing labeling 
that satisfies the requirements of 21 CFR 807.87(e).6 
Directions for use 
 
We recommend clear and concise instructions that delineate the technological features of the 
specific device and how the device is to be used on patients.  Instructions should encourage 
local/institutional training programs designed to familiarize users with the features of the device 
and how to use it in a safe and effective manner. 
                                                           
6 Although final labeling is not required for 510(k) clearance, final labeling must comply with 
the requirements of 21 CFR 801 or 21 CFR 809.10 before a medical device is introduced into 
interstate commerce.  Labeling recommendations in this guidance are consistent with the 
requirements of part 801 and section 809.10. 
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Quality Control 
 
To mitigate the risk of inaccurate results and to assist the user in verifying that the assay and 
assays are performing properly, we recommend that you provide a description of quality control 
recommendations in the labeling.   
Limitations 
 
We recommend that you address the limitations of your assay with statements in the labeling 
such as the following: 
  
  The tissue locations of fungal infection, encapsulation, and the amount of beta-
glucan produced by certain fungi affect the serum concentration of this analyte.  
Reduced ability to contribute beta-glucan to the bloodstream can reduce the 
ability to detect certain fungal infections.  Cryptococcus species (spp.) produce 
low levels of beta-glucan due to the encapsulation of the cell.  Zygomycetes, 
including Absidia, Mucor spp. and Rhizopus spp. are not known to produce beta-
glucan.  
  
  Certain healthy individuals have elevated levels of beta-glucan that fall into an 
equivocal zone.  In such cases, additional testing is recommended. 
 
  The frequency of patient testing will depend upon the relative risk of fungal 
infection.  Sampling rates of at least two to three times per week are 
recommended for at risk patients. 
 
  False positive results have been found in hemodialysis patients, subjects treated 
with certain fractionated blood products such as serum albumin and 
immunoglobulins and specimens (or subjects) exposed to beta-glucan-containing 
gauze. 
 
  Samples that are hemolyzed, lipemic, or contain bilirubin may interfere with 
assay performance. 
 
  Hemodialysis patients can acquire high levels of beta-glucan when certain 
cellulose dialysis membranes are used.  Hemodialysis with cellulose triacetate 
membranes or polymethyl methacrylate membranes does not appear to affect the 
assay. 
 
  Certain surgical gauzes and sponges can leach high levels of beta-glucan that may 
contribute to a transient false positive result for the beta-glucan serological assay.  
 
Warnings and Precautions  
 
We recommend that you include the following warnings and precautions: 
  
    13     Contains Nonbinding Recommendations 
 
  Establish a clean environment in which to perform the assay.  Use materials and 
assays that are certified to be free of interfering levels of beta-glucan.  Please note 
that beta-glucan as well as fungal contamination from the human body, clothes, 
containers, water, and airborne dust may cause interference with the beta-glucan 
serological assay.  
 
  The assay requires rigorous attention to technique and the testing environment.  
Thorough training of the technician in the assay method and in the avoidance of 
contamination is critical for the effectiveness of the assay.  
 
  Use suitable protective clothing and powder-free gloves when handling patient 
specimens. 
 
 
 
 
 
 
 
 
 
 
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