Influenza and Bacterial Pathogen Coinfections in the 20th Century

Table 4

Comparison of coinfection with major bacterial pathogens and influenza by specimen type during pandemic influenza periods^{a, b}.

Bacteria	Specimen	Studies (𝑛)	Estimates from random effects model
			Average % coinfection with influenza virus	95% Confidence interval
S. pneumonia	Sputum/swab	24	40.8	30.3–52.3
	Sterile fluid	4	7.0	2.1–21.4
	Necropsy	12	46.5	24.8–69.7
H. influenza	Sputum/swab	17	14.3	8.6–23.1
	Sterile fluid	2	2.6	0.4–14.6
	Necropsy	9	17.6	6.7–39.1
Streptococcus spp.	Sputum/swab	18	14.6	7.1–27.5
	Sterile fluid	2	1.4	0.02–46.4
	Necropsy	12	19.6	9.5–36.2
Staphylococcus spp.	Sputum/swab	11	13.8	7.7–23.4
	Sterile fluid	2	2.7	0.5–14.1
	Necropsy	11	43.0	20.8–68.5

^aProportions for S. pneumoniae, H. influenzae, Streptococcus spp. and Staphylococcus spp. were different (𝑃=.008, Kruskal-Wallis test: Bonferonni correction, 𝛼=0.025) while utilized sputum/swab specimens to detect coinfection.
^bProportions for S. pneumoniae, H. influenzae, Streptococcus spp. and Staphylococcus spp. were different (𝑃=.02, Kruskal-Wallis test; Bonferonni correction, 𝛼=0.025) while utilized necropsy specimens to detect coinfection.