Diversity of Ceftazidime-Avibactam Resistance Mechanism in KPC2-Producing Klebsiella pneumoniae Under Antibiotic Selection Pressure

Figures & data

Table 1 Antimicrobial Susceptibility and Resistance Mechanism of Klebsiella pneumoniae from Patients

Isolate	MIC (μg/mL)				Carbapenemases	MLST	ESBL	AmpC	Efflux Pump
	IMP	MEM	TGC	CZA
LY0B1	≥64	≥64	0.5	0.5	KPC-2	ST11	–	–	/
LY0B2	≥64	≥64	0.5	0.5	KPC-2	ST11	–	–	/
LY0B3	≥64	≥64	0.5	0.5	KPC-2	ST11	–	–	/
LY0F1-1	≥64	≥64	1	128	KPC-2	ST11	–	–	↑
LY0F1-2	0.25	2	0.5	128	KPC -14	ST11	TEM	–	/
LY0F2	8	32	0.5	128	KPC-44	ST11	–	–	/
HM0B1	≥64	≥64	1	0.5	KPC-2	ST11	–	–	/
HM0F1	0.25	2	1	256	KPC-33	ST11	TEM	–	/

Abbreviations: IMP, imipenem; MEM, meropenem; TGC, tigecycline; CZA, ceftazidime/avibactam; MLST, Multiple-locus sequence typing; ESBL, extended-spectrum beta-lactamase; AmpC, AmpC beta lactamase.

Figure 1 Schedule of antibacterial treatment and isolation of Klebsiella pneumoniae strains. The red arrows represent the time period of medication. The blue arrow represents the specimen collection at the corresponding time.

Abbreviations: IMP, imipenem; MEM, meropenem; CZA, ceftazidime/avibactam.

Figure 2 Isolation of CZA-resistant Klebsiella pneumoniae and detection of the enzyme type of the strain. (A) The top panel shows that CZA-resistant Klebsiella pneumonia was isolated from the puncture fluid sample of patient 1 after 10 days of CZA administration, and the sensitivity of CZA, MEM, and IMP was tested by the K-B method. The bottom panel in (A) and (B) shows that the enzyme types of isolates LY0F1-1, LY0F1-2 and HM0F1 were detected by enzyme inhibitor enhancement experiments and mCIM and eCIM experiments.

Abbreviations: MEM, meropenem; TGC, tigecycline; CZA, ceftazidime/avibactam; mCIM, modified carbapenem inactivation method; eCIM, EDTA-modified carbapenem inactivation method.

Table 2 Antimicrobial Susceptibility and Resistance Mechanism of CZA-Resistant Klebsiella pneumoniae Induced in vitro

Isolate	MIC (μg/mL)				Carbapenemases	MLST	ESBL	AMPc	Efflux Pump
	IMP	MEM	TGC	CZA
LY0B1	≥64	≥64	0.5	0.5	KPC-2	ST11		–	/
LY0F1Y	1	4	1	128	KPC-86	ST11	TEM	–	/
LY0B2	≥64	≥64	0.5	0.5	KPC-2	ST11		–	/
LY0F2Y	≥16	≥64	1	128	KPC-44	ST11		–	/
LY0B3	≥64	≥64	0.5	0.5	KPC-2	ST11		–	/
LY0F3Y	8	32	0.5	128	KPC-44	ST11		–	/
10B	≥16	≥64	0.5	≤2	KPC-2	ST11		–	/
10F	≥16	16	1	64	KPC-87	ST11		–	/
207B	≥16	≥64	0.25	4	KPC-2	ST11		–	/
207F	2	2	0.5	64	KPC-88	ST11	TEM	–	↑
14B	≥16	≥64	2	≤2	KPC-2	ST11		–	/
14F	≥16	32	0.5	256	KPC-2	ST11		–	↑

Abbreviations: IMP, imipenem; MEM, meropenem; TGC, tigecycline; CZA, ceftazidime/avibactam; MLST, Multiple-locus sequence typing; ESBL, extended-spectrum beta-lactamase; AmpC, AmpC beta lactamase.

Table 3 Antimicrobial Susceptibility Changes and the Characteristics of Resistant Phenotypes of Different KPC Mutant Types of CZA Resistant Strains

Carbapenemases	Isolate	Interpretive Categories				ESBL	AMPc	Efflux Pump
		IMP	MEM	TGC	CZA
KPC-2	LY0B1	R	R	S	S	–	–	–
KPC-33/86/88	LYOF1 HMOF1 207F	S/I	S/I	S	R	+	–	–
KPC-44/87	LYOF2 LYOF2Y LYOF3Y	R	R	S	R	–	–	–

Abbreviations: IMP, imipenem; MEM, meropenem; TGC, tigecycline; CZA, ceftazidime/avibactam; MLST, Multiple-locus sequence typing; ESBL, extended-spectrum beta-lactamase; AmpC, AmpC beta lactamase.

Figure 3 ESBL confirmation test of the CZA-resistant Klebsiella pneumoniae (LY0F1Y and 207F) that were produced in vitro.

Abbreviations: CAZ, ceftazidime; CTX, cefotaxime; CAZ/CLA, ceftazidime/clavulanic acid; CTX/CLA, cefotaxime/ clavulanic acid.