Nonutility of procalcitonin for diagnosing bacterial pneumonia in patients with severe COVID-19

Figures & data

Table 1. Demographic, clinical, and laboratory characteristics of COVID-19 patients with bacterial superinfection compared to those with negative lower respiratory culture (LRCx).

Variables shown as median (IQR) except where otherwise specified	Pure viral infection (n = 100)	Bacterial superinfection (n = 85)	p-value
Age, median (IQR)	64.50 (55.00, 76.25)	63.00 (49.00, 69.00)	0.128
Female sex, n (%)	34 (34.0%)	23 (27.1%)	0.308
Body mass index	28.22 (23.92, 35.78)	30.28 (25.63, 36.14)	0.353
ICU admission, n (%)	84 (84.0%)	75 (88.2%)	0.409
Mechanical ventilation, n (%)	57 (57.0%)	68 (80.0%)	<0.001
Renal failure, n (%)	67 (67.0%)	65 (76.5%)	0.156
Shock, n (%)	73 (73.0%)	66 (79.5%)	0.304
Mortality, n (%)	22 (22.0%)	28 (32.9%)	0.095
Steroids within 24 h of LRCx, n (%)	22 (22.0%)	23 (27.1%)	0.424
Tocilizumab within 14d of LRCx, n (%)	67 (67.0%)	47 (55.3%)	0.103
Biomarkers at time of LRCx
PCT	0.40 (0.13, 0.76)	0.30 (0.14, 0.88)	>0.999*
WBC	8.30 (4.80, 13.60)	10.20 (6.00, 14.10)	>0.999*
Creatinine	1.23 (0.82, 2.48)	1.06 (0.71, 1.79)	>0.999*
C-reactive protein	91.85 (30.08, 153.47)	49.75 (15.05, 108.25)	0.289
D-Dimer	2.02 (1.13, 5.00)	2.59 (0.93, 4.61)	>0.999*
Ferritin	1143.00 (653.50, 1982.25)	816.00 (332.50, 1689.75)	0.210
Temperature	98.20 (97.80, 99.23)	98.90 (98.00, 99.75)	0.156
Microbiological data		Count
Staphylococcus aureus, n (%)		34 (34.7%)
Methicillin-resistant S. aureus, n (%)		6 (6.1%)
Pseudomonas aeruginosa, n (%)		12 (12.2%)
Haemophilus influenzae, n (%)		8 (8.2%)
Klebsiella pneumoniae, n (%)		7 (7.1%)
Enterobacter spp, n (%)		7 (7.1%)
Escherichia coli, n (%)		6 (6.1%)
Beta-hemolytic streptococcus, n (%)		5 (5.1%)
Moraxella catarrhalis, n (%)		4 (4.1%)
Other bacterial pathogens†, n (%)		9 (9.2%)
Polymicrobial infection, n (%)		13 (15.3%)

*Bonferroni-adjusted p-values are reported for biomarkers to adjust for multiple comparisons.

†Other bacterial pathogens include species observed < 3 times. These include Streptococcus pneumoniae (2), Serratia marcescens (2), Stenotrophomonas maltophilia (2), Citrobacter koseri (1), Morganella morganii (1), Proteus mirabilis (1).

p-values were calculated via chi-squared test or Kruskal-Wallis test, as appropriate.

Abbreviations: intensive care unit (ICU), lower respiratory culture (LRCx), interquartile range (IQR), procalcitonin (PCT), white blood cell count (WBC).

Figure 1. Serum procalcitonin as a biomarker of bacterial superinfection in patients with severe COVID-19. a, Procalcitonin levels in patients with pure COVID-19 infection and those with bacterial superinfection. b, Receiver operating characteristic curve defining the utility of PCT in diagnosing superinfection. c, Spearman’s rank correlation between biomarkers at the time of LRCx.