Table 2.

Changes in selected indigenous gut microflora populations following exposure to antimicrobial agents in vitro and in vivo.

		Negatively Impacted Populations		Positively Impacted Populations		Refs
	Antimicrobial Agent	Anaerobes	Facultative Anaerobes	Anaerobes	Facultative Anaerobes
Common inducers of CDI	Clindamycin	Bifidobacteria, Bacteroides, Eubacteria, Clostridia	Lactobacilli	No effect	Enterobacteria, Enterococci	[53,107,110,111,112,114,117,130]
	Ciprofloxacin	Anaerobes overall, Bifidobacteria, Bacteroides spp., Clostridia	E. coli (LFE), Lactobacilli, Enterococci	No effect	Enterococci (PD)	[62,131]
	Moxifloxacin	Bifidobacteria, Bacteroides fragilis group, Clostridia	LFE, Enterococci	No effect	Enterococci (PD)	[62]
	Levofloxacin *	Bifidobacteria, Bacteroides fragilis group	LFE, Enterococci, Lactobacilli	No effect	Facultative anaerobes overall	[62]
	Co-amoxyclav	Bifidobacteria, Bacteroides fragilis group, Clostridia	No effect	No effect	Enterococci, LFE	[132]
Infrequent inducers of CDI	Piperacillin tazobactam	Bifidobacteria, Anaerobic cocci	Lactobacilli, Enterococci	No effect	Enterococci, Lactobacilli, Clostridia (PD)	[133]
	Piperacillin tazobactam	Anaerobes overall, Bifidobacteria, Bacteroides fragilis group,	Lactobacilli, LFE,	No Effect	Enterococci, Lactobacilli, Clostridia (PD)	[108]
	Mecillinam	Bifidobacteria	LFE	No effect	No effect	[113]
	Erythromycin	Bifidobacteria, Bacteroides, Clostridia	E. coli, Streptococci, Lactobacilli, Enterococci	Eubacteria	No effect	[134]

PD, post-dosing; LFE, lactose-fermenting Enterobacteriaceae. Underlined bacterial groups were substantially reduced (≥3-log₁₀ cfu/mL). * 1/2 experiments, second experiment demonstrated a reduced antimicrobial effect.