Table 1.

Regulatory RNAs contributing to antimicrobial resistance or susceptibility through known mechanisms.

Small RNA	Organism(s)	Resistance and/or inducer	Mechanism	Reference
I. Attenuators and riboswitches
aac/aad	Various species	Aminoglycosides	Riboswitch controlling translation of aminoglycoside acetyl- or adenyl-transferase genes	Jia et al., 2013
bmrCD	Bacillus subtilis	Antibiotics targeting the ribosome	Attenuator controlling transcription of bmrCD encoding an ABC transporter	Reilman et al., 2014
cat	Various species	Chloramphenicol	Attenuator controlling translation of chloramphenicol acetyltransferase genes	Schwarz et al., 2004
cmlA	Various species	Chloramphenicol	Attenuator controlling translation of chloramphenicol export genes	Schwarz et al., 2004
ermC (A, B)	Various species	MLSB	Attenuator controlling translation of ribosome methylase genes	Ramu et al., 2009
ermK	Bacillus spec.	MLSB	Attenuator controlling transcription of ribosome methylase genes	Kwak et al., 1991
fexA	Staphylococcus lentus	Chloramphenicol, florfenicol	Attenuator controlling translation of a chloramphenicol export gene	Schwarz et al., 2004
lmo0919	Listeria monocytogenes	Lincomycin	Attenuator controlling transcription of an ABC transporter gene	Dar et al., 2016
mef/mel (msR)	Streptococcus	Macrolides	Attenuator controlling transcription of an operon encoding a MFS efflux pump (Mef) and an ABC transporter (Mel)	Chancey et al., 2015
tetM	Enterococcus faecalis	Tetracycline	Attenuator controlling transcription of the ribosomal protection gene tetM	Su et al., 1992
tetQ	Bacteroides	Tetracycline	Attenuator controlling translation of the ribosomal protection gene tetQ	Wang et al., 2005
vmlR	B. subtilis	Lincomycin, virginiamycin M	Attenuator controlling transcription of vmlR encoding an ABC transporter	Ohki et al., 2005
II. Trans-encoded sRNAs
DsrA	E. coli	Oxacillin, erythromycin, novobiocin	Overexpression provides resistance through upregulation of efflux pump MdtEF via RpoS	Nishino et al., 2011
GcvB	E. coli	D-cycloserine	GcvB provides resistance by repression of cycA, which is required for drug uptake	Pulvermacher et al., 2009
GlmY, GlmZ	E. coli, Salmonella	GlmS inhibitors (Bacilysin, Nva-FMDP)	Provide resistance via overproduction of GlmS	Khan et al., 2016
MicF	E. coli, Salmonella	Cephalosporins, norfloxacin	Deletion lowers and overexpression increases resistance through repression of ompF	Kim et al., 2015
MgrR	E. coli	Polymyxin B	MgrR mediates susceptibility by repressing synthesis of EptB, which modifies LPS	Moon and Gottesman, 2009
RybB	E. coli	Epigallocatechin gallate (EGCG)	EGCG activates expression of RybB, which down-regulates the biofilm regulator CsgD leading to inhibition of biofilm formation	Serra et al., 2016
RyhB	E. coli	Colicin Ia	RyhB mediates susceptibility by activation of synthesis of the colicin Ia receptor CirA	Salvail et al., 2013
SdsR (RyeB)	E. coli	Ampicillin	Ampicillin promotes mutations through repression of mutS by SdsR. Mutations may confer resistance	Gutierrez et al., 2013
SdsR (RyeB)	E. coli, Salmonella	Quinolones, novobiocin, crystal violet	Overexpression reduces resistance which is at least partially attributable to repression of tolC by SdsR	Kim et al., 2015; Parker and Gottesman, 2016
SroC	Salmonella	Polymyxin B	SroC contributes to resistance by downregulation of sRNA MgrR	Acuna et al., 2016
SprX (RsaOR)	Staphylococcus aureus	Glycopeptides	Overexpression reduces and deletion increases resistance. SprX acts by repression of spoVG.	Eyraud et al., 2014
3′ETSleuZ	E. coli	Colicin Ia	Contributes to resistance by lowering RyhB levels	Lalaouna et al., 2015

MLS_B, Macrolides, lincosamides, streptogramin B.