Table 4.

Amino acid substitutions detected in C. difficile clinical isolates resistant to fluoroquinolones or rifamycins.

Antibiotic	Target	Amino acid substitution	References
Fluoroquinolones	DNA gyrase subunits	GyrA
		Thr82Ile	Ackermann et al. [2001]; Dridi et al. [2002]; Spigaglia et al. [2008]; Kuwata et al. [2015]
		Thr82Val	Ackermann et al. [2001]; Dridi et al. [2002]; Spigaglia et al. [2008]; Kuwata et al. [2015]; Liao et al. [2012]
		Asp71Val	Dridi et al. [2002]; Walkty et al. [2010]; Liao et al. [2012]
		Ala118Thr	Dridi et al. [2002]
		Val43Asp	Carman et al. [2009]
		Asp81Asn	Huang et al. [2009]; Liao et al. [2012]
		Ala384Asp	Mac Aogáin et al. [2015]
		GyrB
		Asp426Asn	Dridi et al. [2002]; Spigaglia et al. [2008]; Liao et al. [2012]
		Asp426Val	Spigaglia et al. [2008]
		Arg447Lys	Walkty et al. [2010]; Liao et al. [2012]
		Glu466Val	Liao et al. [2012]
		Arg377Gly	Liao et al. [2012]
		Ser416Ala
		GyrA/GyrB
		Thr82Ile/Ser416Ala	Spigaglia et al. [2008]; Liao et al. [2012]
		Thr82Ile/Ser366Ala	Huang et al. [2009]; Kuwata et al. [2015]
		Thr82Val/Asp426Val	Huang et al. [2009]; Liao et al. [2012]
		Thr82Ile/Ser366Ala and Asp426Val	Walkty et al. [2010]; Kuwata et al. [2015]
		Thr82Ile/Asp426Asn	Walkty et al. [2010]; Kuwata et al. [2015]
		Thr82Ile/Leu444Phe	Walkty et al. [2010]
		Thr82Ile/Asp426Val	Spigaglia et al. [2011]
		Thr82Ala/Ser366Ala and Gln434Lys	Kuwata et al. [2015]
Rifamycins	RNA polymerase	RpoB
		His502Tyr	O'Connor et al. [2008]; Pecavar et al. [2012]
		His502Arg	O'Connor et al. [2008]
		Arg505Lys	O'Connor et al. [2008]; Curry et al. [2009]; Miller et al. [2011]; Spigaglia et al. [2011]; Pecavar et al. [2012]
		His502Asn	Miller et al. [2011]; Pecavar et al. [2012]
		Asp492Asn	Pecavar et al. [2012]
		Asp492Val	Pecavar et al. [2012]
		His502Leu	Pecavar et al. [2012]
		Ser550Phe	Pecavar et al. [2012]
		Ser550Tyr	Pecavar et al. [2012]
		Ser448Thr and Arg505Lys	O'Connor et al. [2008]; Curry et al. [2009]
		Asp492Asn and Arg505Lys	O'Connor et al. [2008]
		His502Asn and Arg505Lys	O'Connor et al. [2008]; Curry et al. [2009]; Miller et al. [2011]; Spigaglia et al. [2011]; Pecavar et al. [2012]
		Arg505Lys and Ile548Met	O'Connor et al. [2008]; Curry et al. [2009]; Pecavar et al. [2012]
		Ser498Thr and Arg505Lys	Curry et al. [2009]; Miller et al. [2011]
		Leu487Phe and His502Tyr	Pecavar et al. [2012]
		His502Tyr and Pro496Ser	Carman et al. [2009]