Bacterial and Viral Coinfection in IPF Patients

Bacterial and Viral Coinfection in Idiopathic Pulmonary Fibrosis Patients

The Prevalence and Possible Role in Disease Progression

Mohsen Moghoofei; Shayan Mostafaei; Nasim Kondori; Michelle E. Armstrong; Farhad Babaei

BMC Pulm Med. 2022;22(60)

Abstract and Introduction

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial pneumonia of unknown aetiology with a mean survival rate of less than 3 years. No previous studies have been performed on the role of co-infection (viral and bacterial infection) in the pathogenesis and progression of IPF. In this study, we investigated the role of viral/bacterial infection and coinfection and their possible association with pathogenesis and progression of IPF.

Methods: We investigated the prevalence and impact of bacterial and viral coinfection in IPF patients (n = 67) in the context of pulmonary function (FVC, FEV1 and DLCO), disease status and mortality risk. Using principal component analysis (PCA), we also investigated the relationship between distribution of bacterial and viral co-infection in the IPF cohort

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Abstract and Introduction
Background
Methods
Results
Discussion
Conclusion
References

Table 1. Baseline characteristics of the IPF patients (n = 67)
Characteristics
Age (year)*	62.8 ± 12.44
FVC*	75.3 ± 4.37
FEV₁*	70.9 ± 4.30
DL_CO*	70.5 ± 3.96
Sex⁺
Male	40 (59.7)
Female	27 (40.3)
Disease status⁺
Acute exacerbation	55 (82.1)
(AE-IPF) stable	12 (17.9)
Immunosuppression drugs⁺
Pred 5 mg	2 (3)
Pred 10 mg	5 (7.5)
Pred 20 mg	2 (3)
CyA 125 mg	2 (3)
Unknown	8 (11.9)
Surgical lung biopsy⁺
No	63 (94)
Yes	4 (6)
History of fibrosis in family⁺
No	55 (82.1)
Yes	12 (17.9)
Bacterial infection No. 7 (10.4%)
P. aeruginosa ⁺	17 (27)
S. pneumonia ⁺	17 (27)
S. aureus ⁺	16 (25.4)
K. pneumoniae ⁺	16 (25.4)
H. influenzae ⁺	29 (46)
Viral infection No. 12 (17.9%)
Parainfluenza⁺	12 (19)
Influenza⁺	12 (19)
Adeno⁺	10 (15.9)
Rhinovirus⁺	25 (39.7)
RSV⁺	15 (23.8)
Coronavirus⁺	9 (14.3)
Co-infection⁺ No. 40 (59.7%)
Death⁺
No	49 (73.1)
Yes	18 (26.9)

Ref. considered as the reference level for each categorical variable, NA not available, forced vital capacity, FVC forced expiratory volume 1, FEV₁, diffusing capacity of lung for carbon monoxide: DL_C0
*Indicated as mean ± standard deviation
⁺Indicated as "n" (%)

Table 2. Comparison of pulmonary function indices between non-infected, bacterial-, viral- and co-infected IPF patients, respectively
PFT index	Non-infected Group 1 (n = 8)	Bacterial Infection Group 2 (n = 7)	Viral Infection Group 3 (n = 12)	Coinfection Group 4 (n = 40)	R, Adj. p*	R, Adj. p ⁺	R, Adj. p ^$
FVC	79.7 ± 3.30	76.6 ± 5.19	77.8 ± 2.88	73.7 ± 4.08	0.961, 0.368	0.976, 0.652	0.924, 0.013
FEV₁	73.5 ± 5.0	73.1 ± 5.55	73.1 ± 3.39	69.5 ± 3.82	0.994, 0.996	0.994, 0.992	0.945, 0.152
DL_CO	76.5 ± 1.29	71.7 ± 4.64	71.2 ± 2.73	69.3 ± 3.70	0.937, 0.076	0.93, 0.030	0.905, 0.001

Data represents Mean ± SD
IPF uninfected patients are considered as the reference group (Group 1). The Adj. P is based on the marginally adjusted p values by the Benjamini–Hochberg-FDR correction at α = 0.05. Bold values indicated as statistically significant at p < 0.05 level
PFT pulmonary function test, R ratio
*Comparison between group 2 versus group 1
⁺Comparison between group 3 versus group 1
^$Comparison between group 4 versus group 1

Table 3. Comparison of disease status, survival time and death occurrence between non-infected, bacterial-, viral- and co-infected IPF patients, respectively
Characteristics	Non-infected Group 1 (n = 8)	Bacterial Infection Group 2 (n = 7)	Viral Infection Group 3 (n = 12)	Coinfection Group 4 (n = 40)	p*	p ⁺	p ^$
Disease status⁻ (acute vs. stable)	0	1 (14.3)	1(8.3)	22 (55)	0.675	0.930	< 0.001
Death status⁻ (death vs. survive)	0	2 (28.5)	0	15 (37.5)	0.40	0.622	0.043
Survival time⁺ (months-to-death)	42.5 ± 6.55	38.5 ± 7.02	34.4 ± 2.83	32.9 ± 9.12	0.426	0.193	0.026

Disease- and death-status are indicated as "n" (%). Survival time is indicated as median ± IQR
IPF uninfected patients are considered as the reference group (Group 1). Bold values indicated as statistically significant at p < 0.05 level. Follow up period is 60 months
*Comparison between group 2 versus group 1
⁺Comparison between group 3 versus group 1
^$Comparison between group 4 versus group 1