Plasmid-mediated mcr-1 colistin resistance in Escherichia coli and Klebsiella spp. clinical isolates from the Western Cape region of South Africa

Table 1 Specimen details, colistin susceptibilities and presence of mcr-1 in colistin resistant isolates

Species	Isolate	Specimen type	Date of collection	Hospital	Vitek MIC (μg/ml)	Etest MIC (μg/ml)	mcr-1 PCR	Additional antibiotic resistance
E. coli	CEC1	Urine	25/01/2016	A	4 (R)	4 (R)	+	SXT,
	CEC2	Urine	16/01/2016	F	4 (R)	4 (R)	+	SXT, CIP, CXM(I)
	CEC3	Urine	15/01/2016	D	16 (R)	4 (R)	+	none
	CEC4	Urine	16/01/2016	E	8 (R)	4 (R)	+	SXT, AMP, CXM(I)
	CEC5	Urine	01/02/2016	H	16 (R)^c	0.5 (S)	-	AMI(I)
	CEC7	Superficial abdominal swab	27/01/2016	D	8 (R)	4 (R)	+	SXT, AMP, AMC(I), CIP, CXM(I), TZP(I)
	CEC8	Urine	12/02/2016	A	8 (R)	4 (R)	+	SXT, AMP, CIP
	CEC9	Urine	16/02/2016	B	4 (R)	2 (S)	+	SXT, AMP, CIP
	CEC10	Urine	16/02/2016	C	4 (R)	2 (S)	+	AMP, AMC(I), CIP, CXM, CTX, CAZ, FEP, AMI(I), TZP(I)
	CEC11	Urine	03/03/2016	B	8 (R)	4 (R)	+	SXT, AMP,
	CEC12a	Urine	23/05/2016	A	4 (R)	4 (R)	-	SXT, AMP, AMC(I)
	CEC13	Urine	10/06/2016	G	4 (R)	4 (R)	+	SXT, AMP, CIP, CXM(I), FOX(I)
	CEC14	Urine	27/07/2016	A	4 (R)^c	0.5 (S)	-	none
	CEC15^a	Urine	23/07/2016	A	4 (R)	4 (R)	-	SXT, AMP
K. pneumoniae	CK1^b	Urine	20/05/2016	E	4 (R)	2 (S)	+	AMP, AMC, CIP, CXM, CTX, CAZ, FEP, TZP(I)
	CK2	Sputum	17/06/2016	A	16 (R)	4 (R)	+	SXT, AMP, AMC, CIP, CXM, FOX, CTX, CAZ, FEP, GEN, AMI, TZP, ETP, IPM, MEM
	CK5	Urine	17/07/2016	C	4 (R)	0.5 (S)	+	AMP, CXM
	CK6	Urine	26/07/2016	A	16 (R)	Isolate lost during culture		SXT, AMP, AMC, CIP, CXM, FOX, CTX, CAZ, FEP, GEN, AMI(I), TZP
	CK7^b	Urine	12/08/2016	E	16 (R)	4 (R)	-	SXT, AMP, AMC, CIP, CXM, CTX, CAZ, FEP, GEN, TZP(I)
	CK8	Sputum	02/07/2016	C	4 (R)	0.5 (S)	+	AMP, GEN(I), AMI(I)
K. oxytoca	CK3	Superficial skin swab	21/06/2016	B	16 (R)	0.25 (S)	+	AMP

^aSuccessive E. coli isolates obtained from the same patient. ^bSuccessive K. pneumonia isolates obtained from the same patient. ^cRepeat Vitek susceptibility testing redefined the colistin MIC as 0.5 μg/mL; both these isolates were excluded from further analysis. R resistant, I intermediate, S susceptible, SXT trimethoprim-sulfamethoxazole, CIP ciprofloxacin, CXM cefuroxime, AMP ampicillin, AMI amikacin, AMC amoxicillin-clavulanic acid, TZP piperacillin-tazobactam, CTX cefotaxime/ceftriaxone, CAZ ceftazidime, FEP cefepime, GEN gentamicin, ETP ertapenem. IPM imipenem, MEM meropenem

ISSN: 2047-2994