Evaluation of Three Rapid Diagnostic Methods for Direct Identification of Microorganisms in Positive Blood Cultures

Raquel M. Martinez; Elizabeth R. Bauerle; Ferric C. Fang; Susan M. Butler-Wu

doi:10.1128/JCM.00529-14

DOI: 10.1128/JCM.00529-14

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TABLE 1

Distribution of microorganisms isolated^{^a}

Definitive ID	No. of monomicrobial isolates	No. of polymicrobial isolates	Total no. of isolates (%)
Gram-positive bacteria
CoNS	45	5	50 (28.7)
Staphylococcus aureus	13	2	15 (8.6)
Enterococcus faecium	9	2	11 (6.3)
Enterococcus faecalis	7	0	7 (4.0)
Enterococcus casseliflavus/E. gallinarum	1	0	1 (0.6)
Viridans streptococci	7	1	8 (4.6)
Streptococcus agalactiae	1	0	1 (0.6)
Streptococcus anginosus group	2	1	3 (1.7)
Streptococcus dysgalactiae (group G)	1	0	1 (0.6)
Streptococcus pneumoniae	1	0	1 (0.6)
Streptococcus pyogenes	2	0	2 (1.1)
Micrococcus spp.	3	2	5 (2.9)
Gemella haemolysans	2	0	2 (1.1)
Granulicatella adiacens	1	1	2 (1.1)
Subtotal	95	14	109 (62.6)
Gram-negative bacteria
Escherichia coli	23	0	23 (13.2)
Klebsiella pneumoniae	5	2	7 (4.0)
Enterobacter cloacae	3	1	4 (2.3)
Pseudomonas aeruginosa	2	1	3 (1.7)
Serratia marcescens	1	2	3 (1.7)
Klebsiella oxytoca	0	2	2 (1.1)
Enterobacter asburiae	0	2	2 (1.1)
Chryseobacterim indologenes	1	1	2 (1.1)
Acinetobacter ursingii	1	1	2 (1.1)
Acinetobacter baumannii complex	1	0	1 (0.6)
Burkholderia cepacia complex	1	0	1 (0.6)
Campylobacter jejuni	1	0	1 (0.6)
Citrobacter freundii	0	1	1 (0.6)
Citrobacter koseri	1	0	1 (0.6)
Haemophilus influenzae	1	0	1 (0.6)
Haemophilus parainfluenae	1	0	1 (0.6)
Morganella morganii	1	0	1 (0.6)
Pseudomonas stutzeri	1	0	1 (0.6)
Raoultella sp.	1	0	1 (0.6)
Rhizobium radiobacter	0	1	1 (0.6)
Stenotrophomonas maltophilia	1	0	1 (0.6)
Subtotal	46	14	60 (34.5)
Yeast
Candida parapsilosis	2	0	2 (1.1)
Candida kefyr	1	0	1 (0.6)
Saccharomyces cerevisiae	1	0	1 (0.6)
Cryptococcus neoformans	1	0	1 (0.6)
Subtotal	5	0	5 (2.9)
Total	146	28	174

↵a ID, identification; CoNS, coagulase-negative staphylococcus.

TABLE 2

Evaluation of QuickFISH, BC-GP, and MALDI-TOF MS for 146 monomicrobial cultures

Definitive ID	No. of cultures	No. (%) of cultures correctly identified by:
		MALDI-TOF MS (%)		QuickFISH (%)	BC-GP (%)
		Genus (>1.6)	Species (>1.8)	QuickFISH (%)	BC-GP (%)
Staphylococci	58	57 (98.3)	51 (87.9)	57 (98.3)	58 (100)
CoNS^{^a}	45	44 (97.8)	38 (84.4)	44 (97.8)	45 (100)
S. aureus	13	13 (100)	13 (100)	13 (100)	13 (100)
mecA	3				3 (100)
Enterococci	16	16 (100)	16 (100)	16 (100)	16 (100)
E. faecium	9	9 (100)	9 (100)	9 (100)	9 (100)
E. faecalis	7	7 (100)	7 (100)	7 (100)	7 (100)
vanA	6				4 (66.7)
Streptococci	14	7 (50)	6 (42.9)	14 (100)	12 (85.7)
Viridans streptococci	7	1 (14.3)	1 (14.3)	ND^{^b} (100)	5 (71.4)
S. pyogenes	2	2 (100)	2 (100)	ND (100)	2 (100)
S. anginosus group	2	2 (100)	1 (50)	ND (100)	2 (100)
S. pneumoniae	1	0 (0)	0 (0)	ND (100)	1 (100)
S. agalactiae	1	1 (100)	1 (100)	ND (100)	1 (100)
S. dysgalactiae (group G)	1	1 (100)	1 (100)	ND (100)	1 (100)
Other	7	5 (71.4)	4 (57.1)	7 (100)	7 (100)
Micrococcus spp.	3	1 (33.3)	1 (33.3)	ND (100)	ND (100)
Gemella haemolysans	2	2 (100)	1 (50)	ND (100)	ND (100)
Granulicatella adiacens	1	1 (100)	1 (100)	ND (100)	ND (100)
E. casseliflavus/E. gallinarum	1	1 (100)	1 (100)	ND (100)	ND (100)
Enterobacteriaceae	35	34 (97.1)	32 (91.4)	33 (94.3)	—
E. coli	23	22 (95.7)	22 (95.7)	23 (100)	—
K. pneumoniae	5	5 (100)	5 (100)	3 (60)	—
E. cloacae	3	3 (100)	3 (100)	ND (100)	—
C. koseri	1	1 (100)	1 (100)	ND (100)	—
M. morganii	1	1 (100)	0 (0)	ND (100)	—
Raoultella sp.	1	1 (100)	0 (0)	ND (100)	—
S. marcescens	1	1 (100)	1 (100)	ND (100)	—
Non-Enterobacteriaceae	11	6 (54.5)	5 (45.5)	11 (100)	—
P. aeruginosa	2	2 (100)	2 (100)	2 (100)	—
A. baumannii complex	1	1 (100)	1 (100)	ND (100)	—
A. ursingii	1	0 (0)	0 (0)	ND (100)	—
B. cepacia complex	1	1 (100)	1 (100)	ND (100)	—
C. jejuni	1	0 (0)	0 (0)	ND (100)	—
C. indologenes	1	0 (0)	0 (0)	ND (100)	—
H. influenzae	1	0 (0)	0 (0)	ND (100)	—
H. parainfluenzae	1	0 (0)	0 (0)	ND (100)	—
P. stutzeri	1	1 (100)	0 (0)	ND (100)	—
S. maltophilia	1	1 (100)	1 (100)	ND (100)	—
Yeast	5	3 (60)	3 (60)	5 (100)	—
C. parapsilosis	2	1 (50)	1 (50)	2 (100)	—
C. kefyr	1	1 (100)	1 (100)	ND (100)	—
S. cerevisiae	1	0 (0)	0 (0)	ND (100)	—
C. neoformans	1	1 (100)	1 (100)	ND (100)	—
Total	146	128 (87.7)	117 (80.1)	143 (97.9)	93 (97.9)

↵a CoNS data include the following species: S. epidermidis (37 cultures), S. hominis (4 cultures), S. haemolyticus (2 cultures), S. pasteuri (1 culture), and S. simulans (1 culture).
↵b ND, not detected; —, not done.

TABLE 3

Evaluation of QuickFISH, BC-GP, and MALDI-TOF MS for 13 polymicrobial blood cultures

Blood culture	Definitive ID	Gram stain result^{^a}	Result
Blood culture	Definitive ID	Gram stain result^{^a}	MALDI-TOF MS	QuickFISH	BC-GP
BC245	S. hominis	GPCL	ND^{^b}	CoNS	Staphylococcus sp.
BC245	S. marcescens	GNR	S. marcescens	ND	—^{^c}
BC115	C. freundii	GNR	C. freundii	ND	—
BC115	Micrococcus sp.	ND	ND	—	—
BC31	Viridans streptococci	GPPC	S. pneumoniae	ND	Streptococcus sp.
BC31	S. epidermidis	ND	ND	—	ND
BC44	E. faecium/vanA	GPPC	ND	Not E. faecalis	E. faecium/vanA
BC44	K. pneumoniae	ND	ND	—	—
BC3	K. pneumoniae	GNR	K. pneumoniae	K. pneumoniae	—
BC3	E. cloacae	GNR	ND	E. coli	—
BC124	S. marcescens	GNR	S. marcescens	ND	—
BC124	P. aeruginosa	GNR	ND	ND	—
BC71	K. oxytoca	GNR	ND	ND	—
BC71	Enterobacter asburiae	GNR	E. asburiae	ND	—
BC77	K. oxytoca	GNR	ND	ND	—
BC77	Enterobacter asburiae	GNR	E. asburiae	ND	—
BC37	C. indologenes	GNR	ND	ND	—
	A. ursingii	GNR	ND	ND	—
	R. radiobacter	GNR	ND	ND	—
BC85^{^d}	S. cohnii	GPCL	ND	CoNS	Staphylococcus sp.
BC85^{^d}	Micrococcus sp.	GPCL	ND	ND	ND
BC105^{^d}	S. epidermidis	GPCL	ND	CoNS	ND
	S. hominis	GPCL	ND	CoNS	Staphylococcus sp.
	E. faecium/vanA	ND	E. faecium	—	E. faecium/vanA
BC100^{^d}	S. aureus	GPCL	S. aureus	S. aureus	S. aureus
BC100^{^d}	S. aureus/mecA	GPCL	S. aureus	S. aureus	S. aureus/mecA
BC122^{^d}	S. anginosus group	GPPC	S. anginosus group	Not E. faecalis	S. anginosus group
BC122^{^d}	Granulicatella sp.	GPPC	ND	Not E. faecalis	ND

↵a GNR, Gram-negative rod; GPCL, Gram-positive cocci in clusters; GPPC, Gram-positive cocci in pairs and chains.
↵b ND, not detected.
↵c —, not done.
↵d Excluded from data analysis.

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Table S1 (Pilot evaluation of the BC-GP assay for 107 aerobic and anaerobic blood cultures)

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