VITEK® 2 AST-Gram Negative Ceftazidime is designed for antimicrobial susceptibility testing of Gram negative bacilli and is intended for use with the VITEK® 2 and VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 AST-Gram Negative test. Ceftazidime has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active in vitro and in clinical infections:

Citrobacter species Enterobacter species Escherichia coli Klebsiella species Proteus mirabilis Proteus vulgaris Pseudomonas aeruginosa Serratia species

In vitro data are available, but clinical significance is unknown:

Acinetobacter species Citrobacter koseri (formerly Citrobacter diversus) Citrobacter freundii Providencia species (including Providencia rettgeri) Salmonella species Shigella species Yersinia enterocolitica

The VITEK® 2 Gram-Negative Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant aerobic Gram-negative bacilli to antimicrobial agents when used as instructed.

Device Description

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh(1) and Gerlach(0). The VITEK @2 AST card is essentially a miniaturized, abbreviated and automated version of the doubling dilution technique(3).

Each VITEK® 2 AST card contains 64 wells. A control well which only contains microbiological culture media is resident on all cards. The remaining wells contain premeasured portions of a specific antibiotic combined with culture media. The bacterial or yeast isolate to be tested is diluted to a standardized concentration with 0.45 - 0.5% saline before being used to rehydrate the antimicrobial medium within the card. The VITEK® 2 System automatically fills, seals and places the card into the incubator/reader. The VITEK® 2 Compact has a manual filling, sealing and loading operation. The VITEK® 2 Systems monitor the growth of each well in the card over a defined period of time. At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-GN Ceftazidime (≤0.5 - ≥32 ug/mL) has the following concentrations in the card: 1, 2. 4. 8. and 32ug/mL (equivalent standard method concentration by efficacy in ug/mL).

AI/ML Overview

Here's an analysis of the acceptance criteria and study as described in the provided document for the VITEK® 2 AST-Gram Negative Ceftazidime device:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for Antimicrobial Susceptibility Test (AST) systems are typically defined in the FDA Class II Special Controls Guidance Document. For this device, the guidance specifies performance metrics for Essential Agreement (EA) and Categorical Agreement (CA), along with limits for Very Major Errors (VME), Major Errors (ME), and Minor Errors (mE).

Metric	Acceptance Criteria (from FDA Guidance for AST Systems)	Reported Device Performance (VITEK® 2 AST-GN Ceftazidime)
Overall Essential Agreement (EA)	≥ 90%	96.3% (1054/1095)
Overall Categorical Agreement (CA)	≥ 90%	97.0% (1062/1095)
Overall Very Major Errors (VME)	≤ 1.5%	3.9% (9/228) *
Overall Major Errors (ME)	≤ 3.0%	0.7% (6/863)
Overall Minor Errors (mE)	≤ 10.0%	1.6% (18/1095)
Reproducibility	Not explicitly stated in table, presumed to meet standard	97.04%
VME for Enterobacteriaceae	≤ 1.5%	0.0% (0/46)
ME for Enterobacteriaceae	≤ 3.0%	0.5% (3/557)
mE for Enterobacteriaceae	≤ 10.0%	1.8% (11/605)
VME for Pseudomonas aeruginosa	≤ 1.5%	5.8% (9/155) *Adjusted to 2.6% (4/155)
ME for Pseudomonas aeruginosa	≤ 3.0%	1.1% (3/268)
VME for Acinetobacter spp.	≤ 1.5%	0.0% (0/25)
ME for Acinetobacter spp.	≤ 3.0%	0.0% (0/33)
mE for Acinetobacter spp.	≤ 10.0%	10.3% (6/58)

Note on VME: The overall VME of 3.9% and 5.8% for Pseudomonas aeruginosa initially exceed the typical ≤1.5% acceptance criterion. However, the document provides an explanation and adjustment for Pseudomonas aeruginosa, stating, "Based on the essential agreement and lack of an intermediate breakpoint for ceftazidime with P. aeruginosa, the adjusted very major error rate for P. aeruginosa is 2.6% (4/155)." It also notes that "Seven of the nine very major errors had MIC values of 8 µg/mL; therefore, alternative testing is required prior to reporting results for P. aeruginosa when the VITEK® 2 MIC value is 8 µg/mL." This suggests a mitigation strategy for these specific results. The overall VME is N/A in the table for specific organisms, making it difficult to fully assess the overall VME without further clarification. The document states "The VITEK® 2 AST-GN Ceftazidime demonstrated acceptable performance".

2. Sample Size Used for the Test Set and Data Provenance

The test set consisted of:

Total Isolates: 1095 unique organism-drug combinations (based on the overall EA/CA denominators).
Categories of Isolates: Fresh and stock clinical isolates, as well as a set of challenge strains.
Data Provenance: The study was an "external evaluation" conducted to compare performance with the CLSI broth microdilution reference method. The document does not explicitly state the country of origin but implies a multi-site clinical evaluation given the "external evaluation" terminology for a device seeking FDA clearance in the US. The study appears to be prospective in nature for collecting new performance data.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The ground truth was established by the CLSI broth microdilution reference method. This is a laboratory-based, standardized method, not a consensus of human experts in the traditional sense of medical image interpretation. Therefore, the concept of "number of experts" or "qualifications of experts" does not directly apply here as the ground truth is a technical measurement, not an interpretive one.

4. Adjudication Method for the Test Set

Not applicable. The ground truth is a direct technical measurement (CLSI broth microdilution MIC values), not an interpretive assessment requiring adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

No, this type of study was not performed. The VITEK® 2 AST-Gram Negative Ceftazidime system is a fully automated antimicrobial susceptibility testing device, directly measuring MIC values and providing interpretive categories (Susceptible, Intermediate, Resistant). It does not involve human "readers" or "AI assistance" in the interpretive process like diagnostic imaging tools would.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, this was a standalone performance study. The device, the VITEK® 2 AST-Gram Negative Ceftazidime, functions as an automated system to determine antimicrobial susceptibility. Its performance (MIC readings and categorical interpretations) was evaluated directly against the reference method without human interpretation as part of the operational workflow.

7. The Type of Ground Truth Used

The ground truth used was the CLSI broth microdilution reference method (Clinical and Laboratory Standards Institute). This is a well-established, standardized, and internationally recognized laboratory method for determining the minimum inhibitory concentration of antimicrobial agents.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" or its size. Since this is an in vitro diagnostic device with a defined mechanism (microdilution, growth pattern analysis) rather than a machine learning model requiring extensive training data, the concept of a "training set" in the context of AI/ML algorithms may not fully apply. The device's underlying principles are based on established microbiological methods.

9. How the Ground Truth for the Training Set Was Established

Not applicable, as a distinct "training set" with established ground truth for an AI/ML algorithm is not described or likely relevant for this type of automated AST device. The development of such a device relies on established microbiological principles calibrated against reference methods.

Summary

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December 15, 2020

BioMerieux, Inc. Cherece Jones Staff Regulatory Affairs Specialist 595 Anglum Rd. Hazelwood, Missouri 63042

Re: K193299

Trade/Device Name: VITEK 2 AST-Gram Negative Ceftazidime (≤0.5 - ≥32 µg/mL) Regulation Number: 21 CFR 866.1645 Regulation Name: Fully automated short-term incubation cycle antimicrobial susceptibility system Regulatory Class: Class II Product Code: LON, LTT, LTW

Dear Cherece Jones:

The Food and Drug Administration (FDA) is sending this letter to notify you of an administrative change related to your previous substantial equivalence (SE) determination letter dated September 28, 2020. Specifically, FDA is updating this SE Letter (i.e., correct inaccuracies in the Indications for Use form, 510(k) Summary, and device labeling) as an administrative correction.

Please note that the 510(k) submission was not re-reviewed. For questions regarding this letter please contact Ribhi Shawar, Ph.D., OHT7: Office of In Vitro Diagnostics and Radiological Health, 301-796-6698, Ribhi.Shawar@fda.hhs.gov.

Sincerely,

Ribhi Shawar -S

Ribhi Shawar, Ph.D. (ABMM) Chief, General Bacteriology and Antimicrobial Susceptibility Branch Division of Microbiology Devices OHT7: Office of In Vitro Diagnostics and Radiological Health Office of Product Evaluation and Quality Center for Devices and Radiological Health

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September 28, 2020

bioMérieux, Inc. Cherece Jones Staff Regulatory Affairs Specialist 595 Anglum Rd. Hazelwood, Missouri 63042

Re: K193299

Trade/Device Name: VITEK 2 AST-Gram Negative Ceftazidime (≤0.5 - ≥32 µg/mL) Regulation Number: 21 CFR 866.1645 Regulation Name: Fully Automated Short-Term Incubation Cycle Antimicrobial Susceptibility System Regulatory Class: Class II Product Code: LON, LTT, LTW Dated: November 26, 2019 Received: November 27, 2019

Dear Cherece Jones:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmp/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see

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https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (OS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE(@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

Ribhi Shawar -S

Ribhi Shawar, Ph.D. (ABMM) Chief. General Bacteriology and Antimicrobial Susceptibility Branch Division of Microbiology Devices OHT7: Office of In Vitro Diagnostics and Radiological Health Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known)

K193299

Device Name

VITEK® 2 AST-Gram Negative Ceftazidime (≤ 0.5 - ≥ 32 µg/mL)

Indications for Use (Describe)

Active in vitro and in clinical infections:

Citrobacter species Enterobacter species Escherichia coli Klebsiella species Proteus mirabilis Proteus vulgaris Pseudomonas aeruginosa Serratia species

In vitro data are available, but clinical significance is unknown:

Type of Use (Select one or both, as applicable)

X | Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) SUMMARY

VITEK® 2 AST-Gram Negative Ceftazidime (≤0.5 - ≥32 µg/mL)

510(k) Submission Information:

Submitter's Name:	bioMérieux, Inc.
Address:	595 Anglum RoadHazelwood, MO 63042
Contact Person:	Cherece L. JonesStaff Regulatory Affairs Specialist
Phone Number:	314-731-8684
Fax Number:	314-731-8689
Date of Preparation:	November 26, 2019
Device Name:
Formal/Trade Name:	VITEK® 2 AST-Gram Negative Ceftazidime (≤0.5 - ≥32µg/mL)
Classification Name:	21 CFR 866.1645Fully Automated Short-Term Incubation CycleAntimicrobial Susceptibility SystemProduct Code: LON
Common Name:	VITEK® 2 AST-GN Ceftazidime (≤0.5 - ≥32 µg/mL)
Predicate Device:	VITEK® 2 AST-GN Eravacycline (≤0.12 - ≥4µg/mL) (K191766)

D. Device Description:

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VITEK® 2 AST-GN Ceftazidime (≤0.5 - ≥32 ug/mL) has the following concentrations in the card: 1, 2. 4. 8. and 32ug/mL (equivalent standard method concentration by efficacy in ug/mL).

E. Substantial Equivalence Information:

The similarities and differences of the VITEK® 2 AST-GN Ceftazidime (≤0.5 - ≥32 µg/mL) when compared to the predicate device, VITEK® 2 AST-GN Eravacycline ( ≤ 0.12 –> 4 µg/mL), are described in the Table 1 below.

Table 1: Substantial Equivalence
Item	Device:VITEK® 2 AST-Gram NegativeCeftazidime( $\leq$ 0.5 - $\geq$ 32 µg/mL)	Predicate:VITEK® 2 AST-GN Eravacycline( $\leq$ 0.12 - $\geq$ 4 µg/mL)(K191766)
Intended Use	VITEK® 2 AST-Gram NegativeCeftazidime is designed forantimicrobial susceptibility testing ofGram negative bacilli and is intendedfor use with the VITEK® 2 andVITEK® 2 Compact Systems as alaboratory aid in the determination ofin vitro susceptibility to antimicrobialagents. VITEK® 2 AST-GramNegative Ceftazidime is aquantitative test. Ceftazidime hasbeen shown to be active against moststrains of the microorganisms listedbelow, according to the FDA labelfor this antimicrobial.Active in vitro and in clinicalinfections:Citrobacter speciesEnterobacter speciesEscherichia coli	VITEK® 2 AST-Gram NegativeEravacycline is designed forantimicrobial susceptibility testing ofGram negative bacilli and is intendedfor use with the VITEK® 2 andVITEK® 2 Compact Systems as alaboratory aid in the determination ofin vitro susceptibility to antimicrobialagents. VITEK® 2 AST-GramNegative Eravacycline is a quantitativetest. Eravacycline has been shown tobe active against most strains of themicroorganisms listed below,according to the FDA label for thisantimicrobial.Active in vitro and in clinicalinfections:Citrobacter freundiiEnterobacter cloacaeEscherichia coli
Item	Device:VITEK® 2 AST-Gram NegativeCeftazidime(≤0.5 - ≥32 µg/mL)	Predicate:VITEK® 2 AST-GN Eravacycline( ≤ 0.12 – ≥ 4 µg/mL)(K191766)
Similarities
	Klebsiella species	Klebsiella oxytoca
	Proteus mirabilis	Klebsiella pneumoniae
	Proteus vulgaris
	Pseudomonas aeruginosa	In vitro data are available, but
	Serratia species	clinical significance is unknown:
		Citrobacter koseri
	In vitro data are available, but	Klebsiella (Enterobacter) aerogenes
	clinical significance is unknown:
	Acinetobacter species	The VITEK® 2 Gram-Negative
	Citrobacter koseri (formerly	Susceptibility Card is intended for use
	Citrobacter diversus)	with the VITEK® 2 Systems in clinical
	Citrobacter freundii	laboratories as an in vitro test to
	Providencia species (including	determine the susceptibility of
	Providencia rettgeri)	clinically significant aerobic Gram-
	Salmonella species	negative bacilli to antimicrobial agents
	Shigella species	when used as instructed.
	Yersinia enterocolitica
	The VITEK® 2 Gram-Negative
	Susceptibility Card is intended for
	use with the VITEK® 2 Systems in
	clinical laboratories as an in vitro test
	to determine the susceptibility of
	clinically significant aerobic Gram-
	negative bacilli to antimicrobial
	agents when used as instructed.
Test Methodology	Automated quantitative antimicrobialsusceptibility test for use with theVITEK® 2 and VITEK® 2 CompactSystems to determine the in vitrosusceptibility of microorganisms	Same
Inoculum	Saline suspension of organism	Same
Test Card	Gram Negative (AST-GN)Susceptibility Card	Same
Analysis Algorithms	Growth Pattern Analysis	Same
Instrument	VITEK® 2 and VITEK® 2 CompactSystems	Same
Differences
Antimicrobial Agent	Ceftazidime	Eravacycline

Table 1: Substantial Equivalence

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F. Intended Use:

VITEK® 2 AST-Gram Negative Ceftazidime is designed for antimicrobial susceptibility testing of Gram negative bacilli and is intended for use with the VITEK® 2 and VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 AST-Gram Negative Ceftazidime is a quantitative test. Ceftazidime has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active in vitro and in clinical infections:

Citrobacter species Enterobacter species Escherichia coli Klebsiella species Proteus mirabilis Proteus vulgaris Pseudomonas aeruginosa Serratia species

In vitro data are available, but clinical significance is unknown:

G. Performance Overview and Conclusion:

VITEK® 2 AST-GN Ceftazidime demonstrated substantially equivalent performance when compared with the CLSI broth microdilution reference method, as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (Issued August 28, 2009).

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The Premarket Notification (510[k]) presents data in support of VITEK® 2 AST-GN Ceftazidime. An external evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains. The external evaluations were designed to confirm the acceptability of VITEK® 2 AST-GN Ceftazidime by comparing its performance with the CLSI broth microdilution reference method incubated at 16-20 hrs. The data is representative of performance on both the VITEK® 2 and VITEK® 2 Compact instrument platforms.

The VITEK® 2 AST-GN Ceftazidime demonstrated acceptable performance as presented in Table 2 below:

Antimicrobial	Comment	Essential Agreement Category				Category Agreement				% Reproducibility

		% Error				% Error
		%EA	VME	ME	mE	%CA	VME	ME	mE
Ceftazidime	#, E(Overall)	(1054/1095)96.3	N/A	N/A	N/A	(1062/1095)97.0	(9/228)3.9	(6/863)0.7	(18/1095)1.6	97.04
	#, EEnterobacteriaceae	(592/605)97.9	N/A	N/A	N/A	(591/605)97.7	(0/46)0.0	(3/557)0.5	(11/605)1.8
	#,EPseudomonasaeruginosa	(400/423)94.6	N/A	N/A	N/A	(411/423)97.2	(9/155)5.8*	(3/268)1.1	N/A
	#, EAcinetobacterspp.	(54/58)93.1	N/A	N/A	N/A	(52/58)89.7	(0/25)0.0	(0/33)0.0	(6/58)10.3
	* The overall categorical very major error rate for Ceftazidime when testing Pseudomonas aeruginosa with the VITEK ®2 systemwas 5.8% (9/155). The MIC values of five of the nine very major errors were one doubling dilution from the MIC value obtainedfrom the reference method. Based on the essential agreement and lack of an intermediate breakpoint for ceftazidime with P.aeruginosa, the adjusted very major error rate for P. aeruginosa is 2.6% (4/155). Seven of the nine very major errors had MICvalues of 8 µg/mL; therefore, alternative testing is required prior to reporting results for P. aeruginosa when the VITEK® 2 MICvalue is 8 µg/mL.NOTES:VITEK® 2 AST-Gram Negative Ceftazidime values tended to be in exact agreement or at least one doubling dilution lower whentesting Yersinia enterocolitica compared to the CLSI reference broth microdilution.A limited number of Acinetobacter isolates were available for testing with the manual dilution. Of the 18 isolates tested, 8 had MICvalues that were not evaluable for essential agreement. Of the 10 evaluable MIC values, there were 2 minor categorical errors that

Table 2: VITEK® 2 AST-GN Ceftazidime Performance

were not in essential agreement.

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= US Food and Drug Administration 510(k) cleared

E = External performance data

Ouality Control demonstrated acceptable results.

H. References:

MacLowry, J.D. and Marsh, H.H., Semi-automatic Microtechnique for Serial Dilution Antibiotic 1. Sensitivity Testing in the Clinical laboratory, Journal of Laboratory Clinical Medicine, 72:685-687, 1968.
1. Gerlach, E.H., Microdilution 1: A Comparative Study, p. 63-76. Current Techniques for Antibiotic Susceptibility Testing. A. Balows (ed.), Charles C. Thomas, Springfield, IL, 1974.
1. Barry, A.L., The Antimicrobic Susceptibility Test, Principles and Practices, Lea and Febiger, Philadelphia, PA, 1976.

Regulation Number and Section

§ 866.1645 Fully automated short-term incubation cycle antimicrobial susceptibility system.

(a)
Identification. A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”