Table 5.

Certain Clinical Features Related to Etiology

Clinical Feature	Bacterial Pathogen ± Virus	Normal Flora ± Virus	Virus Only	P Value
Peripheral WBC (per mm3)a	13 100	11 200	8400	.01b
Procalcitonin (ng/mL)a	0.33	0.15	0.2	.13c
Sputum WBC (per mL)a	1.7 × 107	1.0 × 107	3.2 × 106	.003d
14-day mortality (%)	3.0%	3.2%	12.5%	.44e

Abbreviations: WBC, white blood cells.

^aData presented as medians.

^bOverall comparison, P = .01; bacterial pathogen vs normal respiratory flora (NRF), P = .06; all bacterial vs viral, P = .01 (Kruskal-Wallis).

^cOverall comparison, P = .13; bacterial pathogen vs NRF, P = .06; all bacterial vs viral, P = .22 (Kruskal-Wallis).

^dOverall comparison, P = .003; bacterial pathogen vs NRF, P = .04; all bacterial vs viral, P = .01 (Kruskal-Wallis).

^eOverall comparison, P = .44; bacterial pathogen vs NRF, P = .38; all bacterial vs viral, P = .31 (Fisher’s exact).