Table 2.

Abundance and significance of NTHi and other potentially pathogenic bacteria in healthy individuals and various stages of COPD using molecular methods.

Sample	Microbiological analysis	Main findings			Study
		Healthy individuals	Stable COPD disease	AECOPD
Sputum	16S rDNA	N.A.	Baselinea	Significant increase of the Proteobacteria phylum (which includes Haemophilus spp.)	Huang et al. (195)
Sputum	16S rDNA	N.A.	Baselinea	An increase in relative abundance of Haemophilus spp. as well as other bacteria typically associated with exacerbations	Millares et al. (218)
Sputum	16S rDNA	No increase in numbers of proteobacterial sequences following rhinovirus infection	N.A.	Significant increase in numbers of proteobacterial sequences, mainly H. influenzae, following Rhinovirus infection	Molyneaux et al. (190)
Sputum	16S rDNA	N.A.	Baselinea	An increase in the relative abundance of Haemophilus spp. following exacerbation, an increase of Haemophilus following corticosteroid treatment but a decrease after antibiotic treatment	Wang et al. (149)
Sputum	16S rDNA	N.A.	A significant increase in the abundance of Haemophilus with increasing disease severity	No significant increase in abundance of Haemophilus genera during exacerbation	Mayhew et al. (151)

^aComparison of the microbiota sampled from a patient during stable disease (defined as baseline) and during an exacerbation.