Profiles of gyrA Mutations and Plasmid-Mediated Quinolone Resistance Genes in Shigella Isolates with Different Levels of Fluoroquinolone Susceptibility

Figures & data

Table 1 Prevalence of Antimicrobial Resistance in Ciprofloxacin-Susceptible, Intermediate and Resistant Shigella Isolates

Ciprofloxacin MIC (μg/mL)	Serotype	Number	Number of Isolates Resistant to Antimicrobial Agent (%)
			Ampicillin	Gentamicin	Tetracycline	Nalidixic Acid	Cefotaxime	ESBL	SXT
Susceptible (≤0.25)	S. flexneri	5	5	0	1	0	0	0	2
	S. sonnei	5	5	0	0	0	0	0	1
Intermediate (0.5)	S. flexneri	34	34 (100)	11 (32)	25 (74)	34 (100)	16 (47)	16 (47)	30(88)
	S. sonnei	29	29 (100)	12 (41)	14 (48)	29 (100)	25 (86)	21 (72)	21(72)
	S. boydii	2	2	0	2	2	0	0	0
Resistant (≥1)	S. flexneri	37	37 (100)	10 (27)	30 (81)	37 (100)	30 (81)	28 (76)	30(81)
	S. sonnei	6	6 (100)	2 (33)	4 (67)	6 (100)	6 (100)	6 (100)	6 (100)
Total		118	118 (100)	35 (30)	76 (64)	108 (192)	77 (65)	71 (60)	90 (76)

Abbreviations: SXT, trimethoprim-sulfamethoxazole; ESBL, extended-spectrum β-lactamase.

Table 2 Amino Acid Changes in gyrA and parC, and Quinolone Resistance-Related Genetic Determinants in S. flexneri and S. sonnei with Different Levels of Ciprofloxacin Susceptibility

Ciprofloxacin MIC (μg/mL)	Serotype	Number (n=118)	gyrA	parC	PMQR Genes
					qnrA	qnrB	qnrS	aac(6´)-Ib-cr
Susceptible (≤0.25)	S. flexneri	5	–	–	–	–	–	–
	S. sonnei	5	–	–	–	–	–	–
Intermediate (0.5)	S. flexneri	34	S83L	S80I	–	–	–	–
	S. sonnei	29	S83L	S80I	–	–	–	–
	S. boydii	2	S83L	S80I	–	–	–	–
Resistant (≥1)	S. flexneri	37	S83L, D87N	S80I	–	+	–	+ (27%)
	S. sonnei	6	S83L, D87N	S80I	–	+	–	+ (33%)

Table 3 MICs of Quinolones in Shigella Isolates During 2011–2013 and 2014–2018

MICs (μg/mL)		2011–2013 (n=54)			2014–2018 (n=64)		P ^a	Total
		S. flexneri (n=33)	S. sonnei (n=19)	S. boydii (n=2)	S. flexneri (n=43)	S. sonnei (n=21)
Ciprofloxacin	≤0.25	5	5	–	–	–	–	10
	0.5	16	14	2	18	15	0.3	65
	≥1	12	–	–	25	6	0.01	43
Nalidixic acid	≤32	5	5	–	–	–	<0.01	10
	>32	28	14	2	43	21	<0.01	108

Note: ^aP value between Shigella isolates collected during 2011–2013 and 2014–2018.