Two-Center Collaborative Evaluation of Performance of the BD Phoenix Automated Microbiology System for Identification and Antimicrobial Susceptibility Testing of Gram-Negative Bacteria

Maria Grazia Menozzi; Ulrich Eigner; Silvia Covan; Sabina Rossi; Pietro Somenzi; Giuseppe Dettori; Carlo Chezzi; Anne-Marie Fahr

doi:10.1128/JCM.00614-06

DOI: 10.1128/JCM.00614-06

Article Figures & Data

Tables

TABLE 1.

ID results for gram-negative bacilli

Group	No. tested		No. (%) of ID results:			Phoenix ID (n = 1)	Comparator system ID
Group	Species	Isolates	Concordant	Discordant	No ID	Phoenix ID (n = 1)	ATB	VITEK 2
Enterobacteriaceae	27	384	378 (98.4)	5 (1.3)	1 (0.3)	Escherichia coli	C. freundii	C. freundii
						Citrobacter freundii	E. cloacae	E. cloacae
						Enterobacter cloacae	K. oxytoca	K. oxytoca
						Morganella morganii	P. stuartii ^a	No ID
						Shigella boydii	E. coli ^a	No ID
						No ID	C. freundii	C. freundii
Nonfermenters^b	11	110	109 (99.1)	1 (0.9)		Pasteurella multocida	B. cepacia ^a	No ID
Total	38	494	487 (98.6)	6 (1.2)	1 (0.2)

↵ a ATB ID had an unacceptable profile or insufficient discrimination.
↵ b Including one fermentative oxidase-positive strain of Aeromonas sp.

TABLE 2.

Susceptibility test results for Enterobacteriaceae and nonfermenters from Heidelberg and Parma

Group and center	No. of isolates tested	No. of single tests	No. of single test results in interpretive category		% of results with:
Group and center	No. of isolates tested	No. of single tests	I	R	EA	CA	mE	ME	VME
Enterobacteriaceae
Parma	224	10,330	419	2,863	95.0	98.2	1.4	0.1	1.7
Heidelberg	160	7,474	311	1,683	93.9	97.0	1.4	0.8	1.8
Total	384	17,804	730	4,546	94.4	97.6	1.7	0.5	1.8
Nonfermenters^a
Parma	73	1,972	186	971	96.9	97.8	1.7	0.7	0.6
Heidelberg	37	971	127	308	88.0	92.3	5.6	3.0	1.6
Total	110	2,943	313	1,279	93.2	95.5	3.3	1.7	0.9
All
Parma	297	12,302	605	3,834	95.4	98.1	1.4	0.2	1.4
Heidelberg	197	8,445	438	1,991	93.2	96.5	2.4	1.0	1.8
Total	494	20,747	1,043	5,825	94.2	97.3	1.9	0.6	1.6

↵ a Including one fermentative oxidase-positive strain of Aeromonas sp.

TABLE 3.

Susceptibility test results for Enterobacteriaceae

Drug	No. of isolates	Breakpoint standard	No. of isolates in interpretive category			% of results with:
Drug	No. of isolates	Breakpoint standard	S	I	R	EA	CA	mE	ME	VME
Quinolones
Ciprofloxacin	382	NCCLS	320	14	48	99.2	99.5	0.5	0.0	0.0
Gatifloxacin	382	NCCLS	328	13	41	97.9	99.0	1.0	0.0	0.0
Levofloxacin	382	NCCLS	332	12	38	99.2	99.7	0.3	0.0	0.0
Lomefloxacin	382	NCCLS	305	18	59	99.2	99.2	0.8	0.0	0.0
Moxifloxacin	370	Pharm^a	307	16	47	96.2	99.2	0.8	0.0	0.0
Norfloxacin	381	NCCLS	325	16	40	98.4	99.7	0.3	0.0	0.0
Ofloxacin	382	NCCLS	321	13	48	99.2	99.7	0.3	0.0	0.0
Nalidixic acid	379	NCCLS	277		102	96.0	100.0	0.0	0.0	0.0
Aminoglycosides
Amikacin	382	NCCLS	372	6	4	94.0	99.5	0.5	0.0	0.0
Gentamicin	382	NCCLS	328	10	44	97.4	100.0	0.0	0.0	0.0
Kanamycin	363	NCCLS	297	6	60	97.0	100.0	0.0	0.0	0.0
Netilmicin	381	NCCLS	345	8	28	95.3	99.0	1.0	0.0	0.0
Tobramycin	382	NCCLS	323	18	41	96.3	99.2	0.8	0.0	0.0
β-Lactam penicillins
Ampicillin	382	NCCLS	74	11	297	91.2	93.2	4.2	6.8	1.7
Piperacillin	383	NCCLS	206	29	148	86.2	92.7	6.5	1.5	0.0
Ticarcillin	383	NCCLS	139	21	223	91.9	96.3	2.9	1.4	0.4
β-Lactam/β-lactamase inhibitors
Amoxicillin/clavulanate	382	NCCLS	186	24	172	95.2	96.6	2.4	1.1	1.2
Ampicillin/sulbactam	382	NCCLS	146	58	178	90.6	91.6	6.3	2.1	2.8
Piperacillin/tazobactam	381	NCCLS	286	12	83	90.4	96.3	2.9	0.3	2.4
Carbapenems
Imipenem	379	NCCLS	361	13	5	87.6	98.7	1.3	0.0	0.0
Meropenem	377	NCCLS	373	1	3	96.0	99.5	0.5	0.0	0.0
Cephems
Cefazolin	379	NCCLS	167	12	200	93.3	94.7	2.9	1.2	3.5
Cefdinir	382	NCCLS	208	15	159	89.7	93.2	3.9	3.4	2.5
Cefepime	381	NCCLS	325	2	54	92.7	98.7	0.3	0.6	3.7
Cefmetazole	324	NCCLS	222	12	90	92.2	95.7	2.2	1.4	4.4
Cefoperazone	379	NCCLS	257	6	116	91.5	96.6	2.1	1.6	0.9
Cefotaxime	380	NCCLS	295	11	74	96.4	97.6	1.8	0.0	2.7
Cefotetan	381	NCCLS	291	6	84	93.1	96.6	1.8	0.0	7.1
Cefoxitin	382	NCCLS	219	24	139	92.7	96.1	2.4	1.4	2.2
Cefpodoxime	378	NCCLS	241	27	110	89.3	94.4	4.2	0.0	4.5
Ceftazidime	382	NCCLS	298	5	79	95.8	98.7	1.0	0.0	1.3
Ceftibuten	371	NCCLS	282	3	86	89.4	97.3	1.9	0.4	2.3
Ceftizoxime	377	NCCLS	291	4	82	97.2	98.7	0.5	0.7	1.2
Ceftriaxone	382	NCCLS	290	12	80	94.9	96.1	2.6	0.3	5.0
Cefuroxime	381	NCCLS	213	22	146	94.2	97.4	1.0	1.9	1.4
Cephalothin	381	NCCLS	105	44	232	95.4	97.9	0.8	1.0	1.7
Monobactams
Aztreonam	382	NCCLS	299	6	77	97.3	97.9	1.0	0.3	3.9
Folate antagonists
Trimethoprim	382	NCCLS	290		92	91.9	99.0	0.0	0.0	4.3
Trimethoprim/sulfamethoxazole	382	NCCLS	299		83	97.1	97.6	0.0	1.7	4.8
Others
Tetracycline	379	NCCLS	217	26	136	94.5	97.9	1.6	0.5	0.7
Chloramphenicol	382	NCCLS	297	17	68	94.5	96.6	2.6	1.0	0.0
Nitrofurantoin	377	NCCLS	197	97	83	96.6	98.1	1.6	0.5	0.0

↵ a Pharm, pharmaceutical company.

TABLE 4.

Susceptibility test results for Pseudomonas spp.^a

Drug	No. of isolates	No. of isolates in interpretive category			% of results with:
Drug	No. of isolates	S	I	R	EA	CA	mE	ME	VME
Fluoroquinolones
Ciprofloxacin	78	53	4	21	97.4	98.7	1.3	0.0	0.0
Levofloxacin	74	47	4	23	91.9	96.0	4.1	0.0	0.0
Lomefloxacin	78	37	11	30	96.2	98.7	1.3	0.0	0.0
Norfloxacin	78	53	6	19	96.2	97.4	2.6	0.0	0.0
Ofloxacin	77	45	5	27	97.4	98.7	1.3	0.0	0.0
Aminoglycosides
Amikacin	79	69	1	9	91.1	96.2	2.5	0.0	11.1
Gentamicin	79	53	9	17	100.0	100.0	0.0	0.0	0.0
Netilmicin	78	57	6	15	98.7	100.0	0.0	0.0	0.0
Tobramycin	79	62		17	97.5	100.0	0.0	0.0	0.0
β-Lactam penicillins
Piperacillin	79	57		22	92.3	96.2	0.0	1.8	9.1
Ticarcillin	79	56		23	93.7	98.7	0.0	1.8	0.0
β-Lactam/β-lactamase inhibitors
Piperacillin/tazobactam	79	61		18	92.3	97.5	0.0	0.0	11.1
Carbapenems
Imipenem	77	60	6	11	93.5	94.8	5.2	0.0	0.0
Meropenem	77	67	7	3	90.9	98.7	1.3	0.0	0.0
Cephems
Cefepime	78	55	14	9	91.0	97.4	2.6	0.0	0.0
Cefoperazone	78	46	10	22	96.2	96.2	2.6	2.2	0.0
Cefotaxime	79	5	38	36	91.1	91.1	7.6	20.0	0.0
Ceftazidime	77	58	7	12	94.8	97.4	2.6	0.0	0.0
Ceftizoxime	78	3	25	50	91.0	91.0	7.7	33.3	0.0
Ceftriaxone	79	17	29	33	87.3	88.6	10.1	5.9	0.0
Monobactams
Aztreonam	78	51	8	19	91.0	91.0	7.7	2.0	0.0

↵ a The NCCLS breakpoint standard was used for each drug.

TABLE 5.

Susceptibility test results for nonfermentative bacteria other than Pseudomonas spp.^a

Drug	No. of isolates	No. of isolates in interpretive category:			% of results with:
Drug	No. of isolates	S	I	R	EA	CA	mE	ME	VME
Fluoroquinolones
Ciprofloxacin	30	8	3	19	96.7	100.0	0.0	0.0	0.0
Levofloxacin	30	15	1	14	90.0	96.7	3.3	0.0	0.0
Lomefloxacin	30	9	5	16	100.0	100.0	0.0	0.0	0.0
Norfloxacin	30	6	2	22	96.7	100.0	0.0	0.0	0.0
Ofloxacin	29	11	4	14	96.6	96.6	3.5	0.0	0.0
Aminoglycosides
Amikacin	29	12		17	89.7	89.7	6.9	0.0	5.9
Gentamicin	30	8	1	21	96.7	96.7	3.3	0.0	0.0
Netilmicin	30	8	1	21	96.7	96.7	0.0	0.0	4.8
Tobramycin	30	8	1	21	93.3	96.7	0.0	0.0	4.8
β-Lactam penicillins
Piperacillin	30	6	7	17	73.3	76.7	23.3	0.0	0.0
Ticarcillin	30	4	8	18	73.3	76.7	20.0	25.0	0.0
β-Lactam-β-lactamase inhibitors
Ampicillin/sulbactam	30	4	4	22	93.3	93.3	6.7	0.0	0.0
Piperacillin/tazobactam	30	10	6	14	76.7	80.0	16.7	10.0	0.0
Carbapenems
Imipenem	30	11		19	96.7	100.0	0.0	0.0	0.0
Meropenem	29	12	1	16	96.6	96.6	3.5	0.0	0.0
Cephems
Cefepime	30	10	5	15	73.3	93.3	6.0	0.0	0.0
Cefoperazone	30	8	2	20	93.3	93.3	3.3	12.5	0.0
Cefotaxime	30	5	3	22	100.0	100.0	0.0	0.0	0.0
Ceftazidime	29	11	3	15	82.7	82.8	13.8	9.1	0.0
Ceftizoxime	30	5	3	22	96.7	96.7	0.0	0.0	4.6
Ceftriaxone	30	6	2	22	90.0	96.7	3.3	0.0	0.0
Monobactams
Aztreonam	30	4	4	22	96.7	96.7	0.0	25.0	0.0
Folate antagonists
Trimethoprim/sulfamethoxazole	30	17		13	90.0	93.3	0.0	11.8	0.0
Others
Tetracycline	30	9	6	15	100.0	100.0	0.0	0.0	0.0
Chloramphenicol	30	13	2	15	96.7	96.7	0.0	7.7	0.0

↵ a Genera included Achromobacter, Acinetobacter, Alcaligenes, Burkholderia, Stenotrophomonas, and one fermentative oxidase-positive strain of Aeromonas sp. The NCCLS breakpoint was used for each drug.

TABLE 6.

ESBL results for the E. coli and Klebsiella isolates tested in this study

Isolate type and species	No. of results^a:					Result (%) for^b:
Isolate type and species	Total	+ by both tests	PHX+ and REF−	PHX− and REF+	− by both tests	Sensitivity	Specificity	PPV	NPV	Agreement
Clinical
E. coli	71	6	0	0	65	100	100	100	100	100
K. pneumoniae	49	7	0	0	42	100	100	100	100	100
K. oxytoca	27	5	1	0	21	100	95.5	83.3	100	96.3
Challenge
E. coli	31	12	1	1	17	92.3	94.4	92.3	94.4	93.5
K. pneumoniae	20	17	0	0	3	100	100	100	100	100
K. oxytoca	5	3	0	0	2	100	100	100	100	100
Clinical and challenge
E. coli	102	18	1	1	82	94.7	98.8	94.7	98.8	98.0
K. pneumoniae	69	24	0	0	45	100	100	100	100	100
K. oxytoca	32	8	1	0	23	100	95.8	88.9	100	96.9
Total	203	50	2	1	150	98.0	98.7	96.2	99.3	98.5