Performance and impact of a multiplex PCR in ICU patients with ventilator-associated pneumonia or ventilated hospital-acquired pneumonia

Table 2 Performance of multiplex PCR (M-PCR) for the identification of micro-organisms isolated at clinical thresholds

	Organism	True positive (culture = M-PCR)	False positive (M-PCR+/culture −)	False negative (culture+/M-PCR−)	Se (%) [95% CI]	Sp (%) [95% CI]	PPV (%) [95% CI]	NPV (%) [95% CI]
Gram-positive bacteria	Staphylococcus aureus	8	0	3	73	100	100	97
Gram-positive bacteria	Streptococcus pneumoniae	0	0	2	0	100	–	98
Enterobacteriaceae	Citrobacter freundii	0	0	0	–	100	–	100
	Escherichia coli	12	3	1	92	96	80	99
	Enterobacter cloacae complex	4	2	2	67	98	67	98
	Enterobacter aerogenes	1	0	0	100	100	100	100
	Proteus spp.	7	0	0	100	100	100	100
	Klebsiella pneumoniae	9	0	3	75	100	100	97
	Klebsiella oxytoca	2	2	0	100	98	50	100
	Klebsiella variicola	0	1	0	–	99	0	100
	Serratia marcescens	5	0	0	100	100	100	100
	Morganella morganii	1	1	2	33	99	50	98
	Hafnia alvei*	0	0	5	0	100	–	95
	Citrobacter koseri*	0	0	2	0	100	–	98
	Serratia rubidaea*	0	0	1	0	100	–	99
Non-fermenting bacteria	Moraxella catarrhalis	1	1	0	100	99	50	100
	Pseudomonas aeruginosa	31	2	0	100	97	94	100
	Acinetobacter baumannii complex	3	0	0	100	100	100	100
	Stenotrophomonas maltophilia	1	2	0	100	98	33	100
	Legionella pneumophila	2	0	0	100	100	100	100
Others	Pneumocystis jirovecii	0	0	0	–	100	–	100
	Haemophilus influenzae	3	0	1	75	100	100	99
	Mycoplasma pneumoniae	0	0	0	–	100	–	100
	Chlamydophila pneumoniae	0	0	0	–	100	–	100
Total		90	14	22	80 [73–88]	99 [99–100]	87 [80–93]	99 [99–99]

For culture, only bacteria that were superior to diagnostic thresholds (10⁴ CFU/ml for BAL and 10³ CFU/ml for PTC) were considered
*Organisms not screened on the multiplex PCR system

ISSN: 1364-8535