Table 6.

Transferable nature of antibiotic resistance markers and β-lactamase production among 15 ESβL producing isolates of enteric bacteria

β-lactamase producing E. coli donor strains		Characteristics of trans conjugants of E. coli K-12 Smr.
Donor strain	Resistance pattern	B-lactamase production against		Transferred marker	Transfer frequency of Amp marker	β-lactamase production against
		Pn	A	A		Pn	A
E. coli	Pn, A, M, Ce, Co, Do, Nx, Na	+	+	+	2.6 × 10−4	+	+
Shigella sp.	Pn, A, M, Co, Nx, Na	+	+	+	1.5 × 10−5	+	+
Salmonella sp.	Pn, A, M, Ce, Co, C, Cef, Do, T, Cfx, Nx, Nf, Na	+	+	+	1.8 × 10−5	+	+
Shigella sp.	Pn, A, M, Ce, Co, Nf, Na	+	+	+	ND	+	+
E. coli (EC-38)	Pn, A, Co	+	+	+	7.0 × 10−3	+	+
E. coli (Rp 4)	Pn, A, K	+	+	+	8.8 × 10 −4	+	+

ND = Not determined. Pn, penicillin ; A, ampicillin; Ce, cefuroxime; M, methicillin; Co, co-trimoxazole; Cef, cefotaxime; Nx, norfloxacin; Cfx, cefixime; Do, doxycycline; Nf, nitrofurantoin; C, chloramphenicol; T, tetracycline; K, kanamycin and Na, nalidixic acid.