Can colistin susceptibility results determined in multidrug resistant Gram-negative bacteria be used for polymyxin B?

CLSI		Susceptible (μg/mL)	Intermediate(μg/mL)	Resistant(μg/mL)
	Colistin		≤2	≥4
	Polymyxin B		≤2	≥4
EUCAST		Susceptible (mg/L)	Intermediate (mg/L)	Resistant (mg/L)	ECOFF (mg/L)
	Colistin^*	≤2		≥4
	Colistin^**	≤4		≥8
	Polymyxin B^*				2
	Polymyxin B^**				4

ECOFF: epidemiological cut-off value

* E. coli, K. pneumoniae, A. baumannii

** P.aeruginosa

Table 2.

The essential agreement, categorical agreement rates of polymyxin B and resistance rates of colistin and polymyxin B in studied bacteria

			Colistin		Polymyxin B
Bacteria	EA n (%)	CA n (%)	I n (%)	R n (%)	I n (%)	R n (%)
E. coli	47 (79.7)	39 (66.1)	44 (74.6)	15 (25.4)	48 (81.4)	11 (18.6)
K. pneumoniae	75 (81.5)	89 (96.7)	30 (32.6)	62 (67.4)	33 (35.9)	59 (64.1)
P. aeruginosa	57 (90.5)	54 (85.7)	48 (76.2)	15 (23.8)	51 (81.0)	12(19.0)
A. baumannii	39 (72.2)	46 (85.2)	37 (68.5)	17 (31.5)	45 (83.3)	9 (16.7)
Total	218 (81.3)	228 (85.1)	159 (59.3)	109 (40.7)	177 (66.0)	91 (34.0)

[i] EA: Essential agreement, CA: Categorical agreement, I: Intermediate, R: Resistant

[ii] n: Number of isolates,

Table 3.

Differences in MIC values between colistin and polymyxin B among tested isolates

Organisms (n)	Polymyxin B more potent by n (%) of strains			Same MIC	Colistin more potent by n (%) of strains
	3 dilution	2 dilution	1 dilution	n (%)	1 dilution	2 dilution	3 dilution
E.coli (59)	0	4 (6.8)	19 (32.2)	17 (28.8)	11 (18.6)	7 (11.9)	1 (1.7)
K. pneumonia (92)	2 (2.2)	13 (14.1)	39 (42.4)	30 (32.6)	6 (6.5)	2 (2.2)	0
P. aeruginosa (63)	1 (1.6)	4 (6.3)	15 (23.8)	38 (60.3)	4 (6.3)	1 (1.6)	0
A. baumannii (54)	6 (11.1)	9 (16.7)	18 (33.3)	19 (35.2)	2 (3.7)	0	0
Total 268	9 (3.4)	30 (11.2)	91 (34.0)	104 (38.8)	23 (8.6)	10 (3.7)	1 (0.4)

Table 4.

Categorical agreement rates changing according to susceptibility status for colistin-polymyxin B intermediate–resistant isolates

Strains	Colistin	Polymyxin B	% of Categorical agreement
Escherichia coli (I)	44	36	81.8
Escherichia coli(R)	15	3	20
Klebseilla pneumoniae(I)	30	30	100
Klebseilla pneumoniae(R)	62	59	95.2
Escherichia coli+ Klebseilla pneumoniae(I)	74	66	89.2
Escherichia coli+ Klebseilla pneumoniae(R)	77	62	80.5
Pseudomonas aeruginoa(I)	48	45	93.8
Pseudomonas aeruginoa(R)	15	9	60
Acinetobacter baumannii(I)	37	37	100
Acinetobacter baumannii (R)	17	9	52.9
Pseudomonas aeruginoa +Acinetobacter baumannii(I)	85	82	96.5
Pseudomonas aeruginoa +Acinetobacter baumannii(R)	32	18	56.3

[i] I: Intermediate, R: Resistant

Table 5.

MIC values (μg/ml) for colistin and polymyxin B in E. coli and K. pneumoniae bacteria (n = 151)

Grey font numbers indicate the number of strains with equivalent MICs for colistin and polymyxin B

Colistin (mg/L)

>=256

128

12K

1K+1E

1K+3E

1K+8E

1K+3E

5K+9E

2K+7E

2K+2E

2K+4E

1K+9E

0.5

3K+2E

2K+2E

<=0.25

3k+1E

0.25

0.5

128

>=256

Polymyxin B (mg/L)

[i] K: Klebsiella pneumoniae, E: Escherichia coli, n: Numbers

[ii] NOTE: Vertical column for colistin MIC values and horizontal column for polymyxin B MIC values.

Table 6.

MIC values (μg/ml) for colistin and polymyxin B in P.aeruginosa and A. baumannii strains (n = 117)

Grey font numbers indicate the number of strains with equivalent MICs for colistin and polymyxin B.

Colistin (mg/L)

>=256

128

1P+1A

1P+2A

2P+2A

2P+1A

5P+1A

1P+5A

10P+8A

16P+9A

12P+4A

1P+1A

0.5

1P+2A

0.25

0.5

128

>=256

Polymyxin B (mg/L)

[i] A: Acinetobacter baumannii, P: Pseudomonas aeruginosa

[ii] NOTE: Vertical column for colistin MIC values and horizontal column for polymyxin B MIC values.

Table 7.

MIC values and interpretations of colistin and polymyxin B against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii strains

Bac.	Col. MIC	Interp.	Poly. MIC	Int.	Bac.	Col. MIC	Interp.	Poly. MIC	Interp.	Bac.	Col. MIC	Int.	Poly. MIC	Int.	Bac.	Col. MIC	Int.	Poly. MIC	Int.	Bac.	Col. MIC	Int.	Poly. MIC	Int.
E1	1	I	2	I	K1	1	I	1	I	K64	64	R	64	R	P1	2	I	1	I	A1	4	R	0.5	I
E2	1	I	4	R	K2	1	I	1	I	K65	64	R	32	R	P2	4	R	1	I	A2	4	R	2	I
E3	4	R	1	I	K3	1	I	2	I	K66	64	R	32	R	P3	1	I	1	I	A3	8	R	1	I
E4	2	I	1	I	K4	1	I	0.5	I	K67	64	R	32	R	P4	1	I	1	I	A4	256	R	128	R
E5	1	I	2	I	K5	1	I	0.25	I	K68	64	R	16	R	P5	2	I	1	I	A5	2	I	0.5	I
E6	2	I	2	I	K6	1	I	0.5	I	K69	64	R	32	R	P6	4	R	2	I	A6	4	R	4	R
E7	1	I	4	R	K7	2	I	1	I	K70	64	R	16	R	P7	2	I	4	R	A7	2	I	1	I
E8	1	I	2	I	K8	2	I	1	I	K71	64	R	32	R	P8	1	I	2	I	A8	0.5	I	0.5	I
E9	1	I	2	I	K9	2	I	1	I	K72	128	R	64	R	P9	1	I	1	I	A9	2	I	0.25	I
E10	4	R	2	I	K10	2	I	0.5	I	K73	128	R	64	R	P10	1	I	1	I	A10	2	I	2	I
E11	1	I	1	I	K11	2	I	1	I	K74	128	R	32	R	P11	1	I	1	I	A11	2	I	1	I
E12	1	I	2	I	K12	2	I	0.25	I	K75	128	R	128	R	P12	2	I	1	I	A12	16	R	4	R
E13	2	I	2	I	K13	2	I	0.25	I	K76	32	R	16	R	P13	2	I	1	I	A13	2	I	2	I
E14	1	I	2	I	K14	2	I	0.5	I	K77	0.25	I	0.5	I	P14	1	I	1	I	A14	0.5	I	0.5	I
E15	0.5	I	2	I	K15	2	I	1	I	K78	0.25	I	0.5	I	P15	4	R	1	I	A15	2	I	1	I
E16	0.5	I	2	I	K16	2	I	2	I	K79	0.25	I	0.25	I	P16	2	I	1	I	A16	2	I	1	I
E17	1	I	1	I	K17	2	I	2	I	K80	0.25	I	0.25	I	P17	16	R	16	R	A17	1	I	0.5	I
E18	1	I	0.5	I	K18	4	R	8	R	K81	0.25	I	0.25	I	P18	2	I	1	I	A18	2	I	2	I
E19	2	I	1	I	K19	4	R	1	I	K82	0.5	I	0.25	I	P19	2	I	2	I	A19	1	I	2	I
E20	4	R	2	I	K20	4	R	4	R	K83	0.5	I	0.5	I	P20	1	I	1	I	A20	2	I	2	I
E21	2	I	2	I	K21	4	R	2	I	K84	0.5	I	0.5	I	P21	1	I	1	I	A21	0.5	I	0.25	I
E22	2	I	1	I	K22	8	R	2	I	K85	0.5	I	1	I	P22	1	I	1	I	A22	2	I	2	I
E23	1	I	2	I	K23	8	R	8	R	K86	0.5	I	0.5	I	P23	1	I	1	I	A23	2	I	1	I
E24	1	I	4	R	K24	8	R	4	R	K87	0.5	I	0.25	I	P24	8	R	2	I	A24	1	I	1	I
E25	4	R	2	I	K25	16	R	8	R	K88	0.5	I	2	I	P25	8	R	4	R	A25	1	I	1	I
E26	2	I	4	R	K26	16	R	16	R	K89	0.5	I	2	I	P26	8	R	4	R	A26	2	I	2	I
E27	1	I	4	R	K27	16	R	16	R	K90	32	R	32	R	P27	2	I	0.5	I	A27	4	R	1	I
E28	2	I	1	I	K28	16	R	16	R	K91	256	R	128	R	P28	2	I	2	I	A28	256	R	128	R
E29	8	R	2	I	K29	16	R	8	R	K92	16	R	8	R	P29	8	R	1	I	A29	16	R	16	R
E30	4	R	2	I	K30	16	R	16	R						P30	2	I	1	I	A30	2	I	1	I
E31	1	I	4	R	K31	16	R	8	R						P31	2	I	1	I	A31	1	I	1	I
E32	1	I	2	I	K32	32	R	8	R						P32	1	I	1	I	A32	128	R	64	R
E33	2	I	2	I	K33	32	R	16	R						P33	64	R	64	R	A33	1	I	0.5	I
E34	0.5	I	4	R	K34	32	R	16	R						P34	1	I	1	I	A34	32	R	32	R
E35	4	R	4	R	K35	32	R	64	R						P35	0.25	I	1	I	A35	2	I	1	I
E36	1	I	1	I	K36	32	R	32	R						P36	2	I	1	I	A36	64	R	64	R
E37	4	R	2	I	K37	32	R	32	R						P37	2	I	2	I	A37	1	I	1	I
E38	2	I	1	I	K38	32	R	16	R						P38	2	I	1	I	A38	0.5	I	0.25	I
E39	1	I	2	I	K39	32	R	32	R						P39	0.5	I	0.5	I	A39	1	I	0.5	I
E40	4	R	2	I	K40	32	R	16	R						P40	2	I	2	I	A40	1	I	0.25	I
E41	4	R	2	I	K41	32	R	32	R						P41	0.25	I	0.25	I	A41	4	R	8	R
E42	2	I	2	I	K42	32	R	8	R						P42	0.25	I	0.25	I	A42	2	I	0.5	I
E43	4	R	4	R	K43	32	R	16	R						P43	0.5	I	0.25	I	A43	2	I	0.5	I
E44	2	I	2	I	K44	32	R	8	R						P44	4	R	2	I	A44	4	R	1	I
E45	4	R	4	R	K45	32	R	16	R						P45	4	R	4	R	A45	4	R	0.5	I
E46	2	I	4	R	K46	32	R	32	R						P46	2	I	4	R	A46	2	I	0.5	I
E47	1	I	0.5	I	K47	32	R	16	R						P47	2	I	2	I	A47	4	R	0.5	S
E48	2	I	1	I	K48	32	R	16	R						P48	2	I	2	I	A48	2	I	0.5	I
E49	1	I	1	I	K49	32	R	16	R						P49	2	I	2	I	A49	8	R	1	I
E50	4	R	2	I	K50	32	R	16	R						P50	2	I	2	I	A50	2	I	2	I
E51	0.25	I	0.25	I	K51	32	R	32	R						P51	2	I	2	I	A51	2	I	2	I
E52	0.5	I	0.5	I	K52	32	R	32	R						P52	4	R	4	R	A52	1	I	0.5	I
E53	2	I	2	I	K53	32	R	16	R						P53	4	R	4	R	A53	2	I	2	I
E54	4	R	1	I	K54	64	R	32	R						P54	2	I	2	I	A54	2	I	1	I
E55	0.5	I	0.5	I	K55	64	R	32	R						P55	4	R	4	R
E56	2	I	1	I	K56	64	R	16	R						P56	2	I	2	I
E57	2	I	1	I	K57	64	R	32	R						P57	2	I	2	I
E58	2	I	1	I	K58	64	R	16	R						P58	2	I	2	I
E59	4	R	1	I	K59	64	R	64	R						P59	2	I	2	I
					K60	64	R	64	R						P60	2	I	2	I
					K61	64	R	64	R						P61	2	I	2	I
					K62	64	R	32	R						P62	2	I	4	R
					K63	64	R	64	R						P63	4	R	4	R

[i] E: Escherichia coli, K: Klebsiella pneumoniae, P: Pseudomonas aeruginosa, A: Acinetobacter baumannii

[ii] Bac: Bacteria, Poly B: Polymyxin B, Col: Colistin, I: Intermediate, R: Resistant

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DOI: https://doi.org/10.2478/ahem-2023-0017 | Journal eISSN: 1732-2693

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Language: English

Page range: 125 - 132

Submitted on: Jan 31, 2023

Accepted on: Aug 17, 2023

Published on: Nov 14, 2023

Published by: Hirszfeld Institute of Immunology and Experimental Therapy

In partnership with: Paradigm Publishing Services

Publication frequency: 1 issue per year

Keywords:

colistin, polymyxin B,

categorical agreement,

broth microdilution

Related subjects:

Life sciences,

Molecular biology,

Microbiology and virology,

Medicine,

Basic medical science,

Immunology

© 2023 Rıza Adaleti, Nilgün Kansak, Şeyma Çalık, Neslihan Arıcı, Seniha Şenbayrak, Sebahat Aksaray, published by Hirszfeld Institute of Immunology and Experimental Therapy
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 77 (2023): Issue 1 (January 2023)