Characterization of CTX-M ESBLs in Enterobacter cloacae, Escherichia coli and Klebsiella pneumoniae clinical isolates from Cairo, Egypt

Table 2 MIC data of selected β-lactams and characteristics of β-lactamases produced by clinical isolates of Enterobacteriaceae from Egypt

Clinical Isolate	Enzyme characteristics^a				Gene (s) detected by PCR^b	MIC (mg/L) of:
	pI	CTX hydrolysis	Inhibited by			CPD	CPD/CLA	FEP	FEP/CLA	FOX	ATM	IPM
			Clox	CLA
Kp4	5.4	No	No	Yes	bla _TEM	>128	1	>128	0.06	8	128	0.12
Kp8	6.3	No	No	Yes	-^c	>128	2	>128	0.06	8	128	0.12
Kp15	7.6	No	No	Yes	bla _SHV	>128	2	>128	<0.03	8	128	0.12
	8.0	Yes	No	Yes	bla _CTX-M-14
ENT	6.3	No	No	Yes	-^c	>128	2	>128	<0.03	>16	32	0.25
	7.6	No	No	Yes	-^e
	8.0	Yes	No	Yes	bla _CTX-M-14
	8.9	No	Yes	No	-^d
EC	5.4	No	No	Yes	bla _TEM	>128	0.25	>128	<0.03	<4	16	0.12
	6.0	No	No	Yes	-^c
	6.6	No	No	Yes	-^c
	9.0	Yes	No	Yes	bla _CTX-M-15

CPD: cefpodoxime, CPD/CLA: cefpodoxime/clavulanic acid, FEP: cefepime, FEP/CLA: cefepime/clavulanic acid, FOX: cefoxitin, ATM: aztreonam, IPM: imipenem.
^aEnzyme Characteristics: pI: isoelectric point of crude β-lactamase extract preparations; CTX (0.75 mg/L) was used in the substrate-based IEF overlay technique, inhibitors used in the IEF overlay were clavulanic acid (1 mM) and cloxacillin (1 mM).
^b bla _TEM, bla _SHV and bla _CTX-M genes were detected by PCR experiments using specific primers. Only the bla _CTX-M genes were sequenced using primers that flanked the full-length genes (See Methods section).
^cPCR was not done to detect the gene that corresponds to the β-lactamase band on IEF gel.
^dβ-lactamase band focusing at pI value of 8.9, which is inhibited by cloxacillin, corresponds to the chromosomal ampC gene of E. cloacae (PCR data not shown).
^ePCR was negative

ISSN: 1471-2334