Table 2 Comparison of clinical characteristics of term infants and premature infants with viral pneumonia based on coinfection with bacteria

Demographic data

  Gestational age (mean ± std, weeks)

39.2 ± 1.4

38.9 ± 1.2

0.058

32.5 ± 2.4

31.7 ± 2.0

0.441

  Sex (male, %)

74(63.2)

148(65.8)

0.642

18(78.3)

6(85.7)

0.999

  Birth weight (mean ± std, g)

3279 ± 409

3295 ± 359

0.709

1911 ± 421

1890 ± 445

0.908

  Age at admission (median, IQR, days)

20(13–24)

19(13.5–24)

0.579

28(25–36)

31(26–60)

0.631

  PMA (mean ± std, weeks)

——

——

——

37.8 ± 2.4

37.9 ± 2.2

0.965

Clinical symptoms

  Fever (n, %)

32(27.4)

30(13.3)

0.001

2(8.7)

1(14.3)

0.999

  Cough (n, %)

112(95.7)

223(99.1)

0.090

23(100)

7(100)

0.999

  Apnoea (n, %)

7(6.0)

8(3.6)

0.298

9(39.1)

1(14.3)

0.372

  Cyanosis (n, %)

18(15.4)

9(4.0)

 < 0.001

10(43.5)

2(28.6)

0.669

  Tachypnoea (n, %)

74(63.2)

125(55.6)

0.171

19(82.6)

6(85.7)

0.999

  Refusal to feed (n, %)

23(19.7)

56(24.9)

0.276

9(39.1)

2(28.6)

0.999

  Vomit/diarrhoea (n, %)

4(3.4)

20(8.9)

0.060

4(17.4)

2(28.6)

0.603

Physical examination

  Moist rales (n, %)

68(58.1)

155(68.9)

0.047

21(91.3)

4(57.1)

0.068

  Wheezing rales (n, %)

36(30.8)

68(30.2)

0.917

9(39.1)

0(0)

0.071

  Three concave sign (n, %)

60(51.3)

59(26.2)

 < 0.001

12(52.2)

6(85.7)

0.193

Laboratory tests

  WBC (mean ± std, × 10⁹/L)

8.88 ± 3.02

8.57 ± 2.75

0.327

11.24 ± 4.75

9.38 ± 3.29

0.344

  Proportion of neutrophils to WBC (median, IQR, %)

26.70(19.20–34.45)

26.70(20.80–33.60)

0.617

26.00(22.60–31.40)

55.70(28.90–63.80)

0.001

  CRP (median, IQR, mg/L)

2.49(0.77–6.95)

0.38(0.08–1.33)

 < 0.001

1.59(0.52–9.87)

1.11(0.05–5.33)

0.311

Complication

  Respiratory failure (n, %)

31(26.5)

25(11.1)

 < 0.001

12(52.2)

5(71.4)

0.427

  Supplemental oxygen (n, %)

29(24.8)

30(13.3)

0.008

9(39.1)

3(42.9)

0.999

  MV (n, %)

4(3.4)

0(0)

0.024

5(21.7)

2(28.6)

0.999

  HFOV (n, %)

1(0.9)

0(0)

0.342

0(0)

0(0)

——

  CMV (n, %)

0(0)

0(0)

——

2(8.7)

1(14.3)

0.999

  NIV (n, %)

3(2.6)

0(0)

0.072

3(13.0)

1(14.3)

0.999

  HF (n, %)

6(5.1)

3(1.3)

0.085

3(13.0)

2(28.6)

0.565

  Diuretic agents (n, %)

6(5.1)

3(1.3)

0.085

3(13.0)

2(28.6)

0.565

  Inotropic agents (n, %)

6(5.1)

3(1.3)

0.085

3(13.0)

2(28.6)

0.565

  Vasodilator agents (n, %)

5(4.3)

2(0.9)

0.090

3(13.0)

1(14.3)

0.999

  PALS (n, %)

3(2.6)

3(1.3)

0.698

2(8.7)

0(0)

0.999

  Pneumothorax (n, %)

3(2.6)

2(0.9)

0.453

2(8.7)

0(0)

0.999

  Pneumomediastinum (n, %)

2(1.7)

1(0.4)

0.563

0(0)

0(0)

——

  Hyponatremia (n, %)

35(29.9)

63(28.0)

0.710

14(60.9)

4(57.1)

0.999

  Duration of hospital stay (median, IQR, days)

11(9–13)

11(9–13)

0.692

22.13 ± 11.01

12.86 ± 7.20

0.046