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Test ID CFRCS Bacterial Culture, Cystic Fibrosis with Antimicrobial Susceptibilities, Varies


Shipping Instructions


Specimen must be received in laboratory within 48 hours of collection.

 

For shipping information see Infectious Specimen Shipping Guidelines in Special Instructions.



Necessary Information


Specimen source is required.



Specimen Required


Submit only 1 of the following specimens:

 

Preferred:

Specimen Type: Sputum, expectorated or induced

Container/Tube: Sterile container

Specimen Volume: Entire collection

 

Acceptable:

Specimen Type: Bronchial aspirate or washing, bronchoalveolar lavage, endotracheal, or tracheal

Container/Tube: Sterile container

Specimen Volume: Entire collection

 

Specimen Type: Throat swab

Supplies:

Culturette (BBL Culture Swab) (T092)

BD E-Swab (T853)

Container/Tube: Culture transport swab (Dacron or rayon swab with aluminum or plastic shaft with either Stuart or Amies liquid medium)

Specimen Volume: Entire collection


Useful For

Detection of aerobic bacterial pathogens in specimens from patients with cystic fibrosis

 

Determining the in vitro antimicrobial susceptibility of potentially pathogenic aerobic bacteria, if appropriate

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
COMM Identification Commercial Kit No, (Bill Only) No
RMALD Ident by MALDI-TOF mass spec No, (Bill Only) No
GID Bacteria Identification No, (Bill Only) No
ISAE Aerobe Ident by Sequencing No, (Bill Only) No
REFID Additional Identification Procedure No, (Bill Only) No
SALS Serologic Agglut Method 1 Ident No, (Bill Only) No
EC Serologic Agglut Method 2 Ident No, (Bill Only) No
SHIG Serologic Agglut Method 3 Ident No, (Bill Only) No
STAP Identification Staphylococcus No, (Bill Only) No
STRP Identification Streptococcus No, (Bill Only) No
BLA Beta Lactamase No, (Bill Only) No
MIC Sensitivity, MIC No, (Bill Only) No
SUS Susceptibility No, (Bill Only) No
SIDC Ident Serologic Agglut Method 4 No, (Bill Only) No
PCRID Identification by PCR No, (Bill Only) No
MARP1 mecA PCR (Bill Only) No, ( Bill Only) No

Testing Algorithm

When this test is ordered, the reflex tests may be performed at an additional charge. Antimicrobial agent appropriate to the organism and specimen source will be tested according to Mayo Clinic's practice.

 

The following tables provide a listing of the antimicrobials routinely tested in the laboratory as well as antimicrobials that may be tested upon request. These tables are organized by isolate groups and are not all inclusive. Call 800-533-1710 and ask to speak to the Bacteriology Antimicrobial Susceptibility Testing Laboratory if the organism or antimicrobial of interest are not listed in these tables.

•

 Aerobic Gram-Negative Bacilli Antimicrobials 

•

 Additional Gram-Negative Bacteria Antimicrobials 

•

 Staphylococcus, Enterococcus, Bacillus, and Related Genera Antimicrobials 

•

 Additional Gram-Positive Bacteria Antimicrobials 

Method Name

Conventional Culture Technique with Minimum Inhibitory Concentration (MIC) by Agar Dilution (if appropriate)

Reporting Name

Bacterial Culture,Cystic Fib +Susc

Specimen Type

Varies

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated 48 hours

Clinical Information

Life expectancy of patients with cystic fibrosis (CF) has increased steadily over the past 50 years, in large part due to improvements in the management of lung disease in this patient population. Still, chronic lung infection is responsible for 75% to 85% of deaths in patients with CF. Appropriate treatment for the causative organism can reduce morbidity and mortality.

 

The number of microbial species associated with CF lung disease is relatively limited. These include Pseudomonas aeruginosa (mucoid and nonmucoid), Staphylococcus aureus, Burkholderia cepacia complex, Stenotrophomonas maltophilia, other non-fermenting Gram-negative rods, Haemophilus influenzae, and Streptococcus pneumoniae. Nontuberculous mycobacteria and Aspergillus species may also play a role in CF lung disease, in addition to common respiratory viruses. This culture is specifically designed and utilizes conventional and additional selective media (compared to non-CF respiratory cultures) to isolate bacteria commonly associated with pulmonary disease in patients with CF.

 

In selected centers, lung transplantation is performed on patients with CF. This test is appropriate for lung transplant patients with underlying CF because they can continue to harbor the same types of organisms as they did prior to transplantation. Patients with CF may be colonized or chronically infected by these organisms over a long period of time.

 

Antimicrobial susceptibility testing determines the minimal inhibitory concentration (MIC) value of selected antimicrobial agents against isolated potentially pathogenic bacteria. The MIC is the lowest antimicrobial concentration (of a series of increasing concentrations) that inhibits growth of the bacterium. Agar dilution MIC testing is performed by testing for growth of bacteria on agar plates containing varying concentrations of antimicrobial agents.

 

For each organism-antimicrobial agent combination, the Clinical and Laboratory Standards Institute provides interpretive criteria for determining whether the MIC should be interpreted as susceptible, susceptible-dose dependent, intermediate, nonsusceptible, resistant, or epidemiological cutoff value (ECV).

Reference Values

No growth or usual flora

 

Identification of probable pathogens:

Results are reported as minimal inhibitory concentration (MIC) in mcg/mL. Breakpoints (also known as "clinical breakpoints") are used to categorize an organism as susceptible, susceptible-dose dependent, intermediate, resistant, nonsusceptible, or epidemiological cutoff value according to the Clinical and Laboratory Standards Institute (CLSI) guidelines.

 

In some instances an interpretive category cannot be provided based on available data and the following comment will be included: "There are no established interpretive guidelines for agents reported without interpretations."

 

Susceptible (S):

A category defined by a breakpoint that implies that isolates with an MIC at or below or a zone diameter at or above the susceptible breakpoint are inhibited by the usually achievable concentrations of antimicrobial agent when the dosage recommended to treat the site of infection is used, resulting in likely clinical efficacy.

 

Susceptible-Dose Dependent (SDD):

A category defined by a breakpoint that implies that susceptibility of an isolate depends on the dosing regimen that is used in the patient. In order to achieve levels that are likely to be clinically effective against isolates for which the susceptibility testing results (either MICs or zone diameters) are in the SDD category, it is necessary to use a dosing regimen (ie, higher doses, more frequent doses, or both) that results in higher drug exposure than that achieved with the dose that was used to establish the susceptible breakpoint. Consideration should be given to the maximum approved literature-supported dosage regimen, because higher exposure gives the highest probability of adequate coverage of a SDD isolate. The drug label should be consulted for recommended doses and adjustment for organ function.

 

Intermediate (I):

A category defined by a breakpoint that includes isolates with MICs or zone diameters within the intermediate range that approach usually attainable blood and tissue levels and for which response rates may be lower than for susceptible isolates.

Note: The intermediate category implies clinical efficacy in body sites where the drugs are physiologically concentrated or when a higher than normal dosage of a drug can be used. This category also includes a buffer zone, which should prevent small, uncontrolled, technical factors from causing major discrepancies in interpretations, especially for drugs with narrow pharmacotoxicity margins.

 

Resistant (R):

A category defined by a breakpoint that implies that isolates with an MIC at or above the resistant breakpoint are not inhibited by the usually achievable concentrations of the agent with normal dosage schedules and that demonstrate MICs that fall in the range in which specific microbial resistance mechanisms are likely, and clinical efficacy of the agent against the isolate has not been reliably shown in treatment studies.

 

Nonsusceptible (NS):

A category used for isolates for which only a susceptible breakpoint is designated because of the absence or rare occurrence of resistant strains. Isolates for which the antimicrobial agent MICs are above or the zone diameters are below the value indicated for the susceptible breakpoint should be reported as nonsusceptible.

Note: An isolate that is interpreted as nonsusceptible does not necessarily mean that the isolate has a resistance mechanism. It is possible that isolates with MICs above the susceptible breakpoint that lack resistance mechanisms may be encountered within the wild-type distribution subsequent to the time the susceptible-only breakpoint was set.

 

Epidemiological Cutoff Value (ECV):

The minimal inhibitory concentration (MIC) that separates microbial populations into those with and without phenotypically detectable resistance (non-wild-type or wild-type, respectively). The ECV defines the highest MIC for the wild type population of isolates. ECVs are based on in vitro data only, using MIC distributions. ECVs are not clinical breakpoints, and the clinical relevance of ECVs for a particular patient has not yet been identified or approved by CLSI or any regulatory agency.

 

When an ECV is reported, the following comment will be included: "This MIC is consistent with the Epidemiological Cutoff Value (ECV) observed in isolates (WITH / WITHOUT) acquired resistance; however, correlation with treatment outcome is unknown."

 

(Clinical and Laboratory Standards Institute: Performance Standards for Antimicrobial Susceptibility Testing. 30th ed. CLSI supplement M100. Clinical and Laboratory Standards Institute; 2020)

Interpretation

A negative test result is no growth of bacteria or growth of only usual flora. A negative result does not rule out all causes of infectious lung disease (see Cautions).

 

Organisms associated with lower respiratory tract infections are reported.

 

For positive test results, pathogenic bacteria are identified. Patients with cystic fibrosis (CF) may be colonized or chronically infected by some organisms over a long period of time, therefore, positive results must be interpreted in conjunction with previous findings and the clinical picture to appropriately evaluate results.

 

A susceptible category result and a low minimum inhibitory concentration value indicate in vitro susceptibility of the organism to the antimicrobial tested.

 

For interpretation of various antimicrobial susceptibility interpretive categories (ie, susceptible, susceptible-dose dependent, intermediate, nonsusceptible, resistant, or Epidemiological Cutoff Value: ECV), see Reference Values section.

Clinical Reference

1. Miller JM, Binnicker MJ, Campbell S, et al: A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology. Clin Infect Dis. 2018 Aug 31;67(6):e1-e94. doi: 10.1093/cid/ciy381

2. York MK, Gilligan P, Alby K: Lower respiratory tract cultures. In: Leber AL, ed. Clinical Microbiology Procedures Handbook, Vol 1, 4th ed. ASM Press; 2016:section 3.11.2

3. LiPuma JJ, Currie BJ, Peacock SJ, VanDamme PAR: Burkholderia, Stenotrophomonas, Ralstonia, Cupriavidus, Pandoraea, Brevundimonas, Comamonas, Delftia, and Acidovorax. In: Carroll KC, Pfaller MC, eds. Manual of Clinical Microbiology. 12th ed. ASM Press; 2019:807-828

4. Clinical and Laboratory Standards Institute: Performance Standards for Antimicrobial Susceptibility Testing. 30th ed. CLSI supplement M100. CLSI; 2020: 3-5 and 254

Day(s) and Time(s) Performed

Monday through Sunday

Analytic Time

5 days

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

87070-Bacteria, culture, cystic fibrosis, respiratory

87186-Antimicrobial Susceptibility, Aerobic Bacteria, MIC-per organism for routine battery (if appropriate)

87181-Susceptibility per drug and per organism for drugs not in routine battery (if appropriate)

87077-Identification commercial kit (if appropriate)

87077-Ident by MALDI-TOF mass spec (if appropriate)

87077-Bacteria Identification (if appropriate)

87077-Additional Identification procedure (if appropriate)

87077-Identification Staphylococcus (if appropriate)

87077-Identification Streptococcus (if appropriate)

87147 x 1-3-Serologic agglut method 1 ident (if appropriate)

87147-Serologic agglut method 2 ident (if appropriate)

87147 x 4-Serologic agglut method 3 ident (if appropriate)

87147 x 2-6-Serologic Agglut Method 4 Ident (if appropriate)

87153-Aerobe Ident by Sequencing (if appropriate)

87185-Beta lactamase (if appropriate)

87150-Identification by PCR (if appropriate)

87150-mecA PCR (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CFRCS Bacterial Culture,Cystic Fib +Susc 44798-7

 

Result ID Test Result Name Result LOINC Value
CFRCS Bacterial Culture,Cystic Fib +Susc 44798-7

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.