Antimicrobial Susceptibility of Mycobacterium abscessus Complex Clinical Isolates from a Chinese Tertiary Hospital

Figures & data

Table 1 Antimicrobial Susceptibility of 129 Mycobacterium abscessus Complex (MABC) Isolates

Subspecies/Antimicrobial Agents	MIC50 MIC90 Range			Susceptibility % (n)			erm(41)
							Sequevars (n)
	(µg/mL)			R	I	S
Mycobacterium abscessus subsp. abscessus (n=97)
Aminoglycosides
Amikacin	16	32	2–>64	4.1	30.9	63.9	T(28) 86;
Tobramycin	16	>16	2–>16	91.8	6.2	2.1	C(28) 10
Cephalosporins							Truncated(1)
Cefoxitin	64	128	16–>128	34.0	56.7	9.3
Cefepime^a	>32	>32	32–>32	100	0	0
Ceftriaxone^a	>64	>64	32–>64	99	1	0
Carbapenem
Imipenem	16	64	2–>64	41.2	45.4	13.4
Fluoroquinolones
Ciprofloxacin	>4	>4	2–>4	93.8	6.2	0
Moxifloxacin	>8	>8	0.5–>8	94.9	3.1	2.1
Folate pathway inhibitor
SXT	>8	>8	1–>8	94.9	–	5.1
Tetracyclines
Tigecycline	1	4	0.12–>4	11.3	–	88.7
Minocycline^a	>8	>8	4–>8	94.9	3.1	2.1
Doxycycline	>16	>16	0.5–>16	87.6	8.3	4.1
Macrolide
Clarithromycin - 3days	1	16	0.06–>16	14.4	0	85.6
Clarithromycin - 14days	16	>16	0.06–>16	88.7	0	11.3
Oxazolidinone
Linezolid	>32	>32	2–>32	86.6	8.3	5.2
β-Lactam/β-lactamase inhibitor combinations
AMC^a	>64	>64	32–>64	99	1	0
Mycobacterium abscessus subsp. massiliense (n=13)							Truncated(13)
Aminoglycosides							rrl(1)
Amikacin	16	32	8–32	0	38.5	61.5
Tobramycin	>16	>16	4–>16	92.3	7.7	0
Cephalosporins
Cefoxitin	64	128	32–128	46.1	53.9	0
Cefepime^a	>32	>32	16–>32	92.3	7.7	0
Ceftriaxone^a	>64	>64	64–>64	100	0	0
Carbapenem
Imipenem	16	32	2–32	23.1	69.2	7.7
Fluoroquinolones
Ciprofloxacin	>4	>4	2–>4	92.3	7.7	0
Moxifloxacin	>8	>8	2–>8	84.6	15.4	0
	(µg/mL)			R	I	S
Folate pathway inhibitor
SXT	>8	>8	1–>8	84.6	-	15.4
Tetracyclines
Tigecycline	2	4	0.5–4	15.4	-	84.6
Minocycline^a	>8	>8	8–>8	100	0	0
Doxycycline	>16	>16	4–>16	84.6	15.4	0
Macrolide
Clarithromycin - 3days	0.5	2	0.06–>16	7.7	0	92.3
Clarithromycin - 14days	0.5	2	0.06–>16	7.7	0	92.3
Oxazolidinones
Linezolid	>32	>32	16–>32	76.9	15.4	7.7
β-Lactam/β-lactamase inhibitor combinations
AMC^a	>64	>64	16–>64	92.3	0	7.7
Mycobacterium abscessus subsp. bolletii (n=19)							No mutations
Aminoglycosides
Amikacin	16	32	2–64	5.3	21	73.7
Tobramycin	16	>16	4–>16	89.5	10.5	0
Cephalosporins
Cefoxitin	128	128	32–>128	63.2	36.8	0
Cefepime^a	>32	>32	32–>32	100	0	0
Ceftriaxone^a	>64	>64	64–>64	100	0	0
Carbapenem
Imipenem	16	32	2–32	47.4	31.6	21
Fluoroquinolones
Ciprofloxacin	>4	>4	4–>4	100	0	0
Moxifloxacin	>8	>8	2–>8	94.8	5.2	0
Folate pathway inhibitor
SXT	>8	>8	2–>8	94.5	-	5.3
Tetracyclines
Tigecycline	2	4	0.25–4	15.8	-	84.2
Minocycline^a	>8	>8	8–>8	100	0	0
Doxycycline	>16	>16	2–>16	89.5	10.5	0
Macrolide
Clarithromycin - 3days	1	16	0.5–>16	26.3	0	73.7
Clarithromycin - 14days	16	>16	2–>16	94.7	0	5.3
Oxazolidinone
Linezolid	>32	>32	8–>32	73.7	5.3	21
β-Lactam/β-lactamase inhibitor combinations
AMC^a	>64	>64	64–>64	100	0	0

Note: ^aDrugs out of guidelines.

Abbreviations: R, resistance; I, intermediate; S, susceptible; No mutations, There were no erm or rrl mutations in the M. bolletii isolates; SXT, trimethoprim/sulfamethoxazole; AMC, amoxicillin/clavulanic acid.

Table 2 Antimicrobial Concentration Ranges for Drug Susceptibility Testing and MIC Breakpoints of Antimicrobial Agents

Antimicrobial Agents	Tested Concentration	Breakpoints (µg/mL)
	Ranges (µg/mL)	R	I	S
Cephalosporins
Cefoxitin	4–128	≥128	32–64	≤16
Cefepime	1–32	≥32	16	≤8
Ceftriaxone	4–64	≥64	32	≤16
Carbapenem
Imipenem	2–64	≥32	8–16	≤4
Aminoglycosides
Amikacin	1–64	≥64	32	≤16
Tobramycin	1–16	≥8	4	≤2
Oxazolidinone
Linezolid	1–32	≥32	16	≤8
Fluoroquinolones
Ciprofloxacin	0.12–16	≥4	2	≤1
Moxifloxacin	0.25–8	≥4	2	≤1
Tetracyclines
Tigecycline	0.015–4	≥4	–	<4
Minocycline	43,838	≥8	2–4	≤1
Doxycycline	0.12–16	≥8	2–4	≤1
Macrolide
Clarithromycin	0.06–16	≥8	4	≤2
Folate pathway inhibitors
SXT	0.25/4.75–8/152	≥4/76	–	≤2/38
β-Lactam/β-lactamase inhibitor combinations
AMC	2/164/32	≥64	32	≤16

Abbreviations: R, resistance; I, intermediate; S, susceptible.

Table 3 Antimicrobial Activities Imipenem (IPM), Ceftazidime (CAZ), and Avibactam (AVI) Alone or in Combination, Against 129 Mycobacterium abscessus Complex (MABC) Isolates

Strain	MIC (µg/mL)
	CAZ	CAZ+	IPM	IPM+	IPM +	IPM+
		AVI4		AVI4	CAZ100	CAZ100+
						AVI4
Avg MIC50	512	512	16	16	4	4
Avg MIC90	1024	1024	32	32	8	8
M. abscessus ATCC 19,977	512	512	8	4	1	1

Abbreviations: Avg, average; CAZ, ceftazidime; AVI, avibactam; IPM, imipenem; CAZ100, 100µg/mL ceftazidim; AVI4, 4µg/mL avibactam.