Plasmid-Encoded Multidrug Resistance of Salmonella typhi and some Enteric Bacteria in and around Kolkata, India: A Preliminary Study



Table 1: Results of transfer experiments and minimum inhibitory concentrations (MICs) of antibiotics for donors
and transconjugants

Set No.

Donor strain
(Resistance
Pattern)

Recipient strain
(Resistance
Pattern)

T ransconj ugant
(Resistance Pattern)

Conjugation
frequency

MICs (m g/ml) of
Donor and

T ransconj ugant

I

S. typhi BS13
(ACCoT)

E. coli C600 (Nx)

E. coli C600 [pBS13]
(ACCoTNx)

0.83 × 10-5

A (5000)
C (5OOo)
Co (1200)
T (500)

E. coli C600
[pBS13]
(ACCoTNx)

S. typhi B72
(Sensitive)

S. typhi B72 [pBS13]
(ACCoT)

0.68 × 10-7

A (5000)
C (5θθθ)
Co (1200)
T (500)

II

S. typhi AS12
(ACCoT)

E. coli C600
(Nx)

E. coli C600 [pAS12]
(ACCoTNx)

0.73 × 10-5

A (5000)
C (5000)
Co (1200)
T (500)

E. coli C600
[pAS12]
(ACCoTNx)

S. typhi B72
(Sensitive)

S. typhi B72 [pAS12]
(ACCoT)

0.12 × 10-6

A (5000)
C (5θθθ)
Co (1200)
T (500)

III

S. typhi M54
(ACCoT)

E. coli C600
(Nx)

E. coli C600 [pM54]
(ACCoTNx)

0.78 × 10-5

A (2000)
C (5000)
Co (1200)
T (800)

E. coli C600
[pM54]
(ACCoTNx)

S. typhi B72
(Sensitive)

S. typhi B72 [pM54]
(ACCoT)

0.38 × 10-7

A (2000)
C (5θθθ)
Co (1200)
T (800)

IV

S. typhi B2/92
(ACCoT)

E. coli C600
(Nx)

E. coli C600 [pB2/92]
(ACCoTNx)

0.89 × 10-5

A (2000)
C (25θθ)

Co (500)
T(450)

E. coli C600
[pB2/92]
(ACCoTNx)

S. typhi B72
(Sensitive)

S. typhi B72 [pB2/92]
(ACCoT)

0.62 × 10-7

A (2000)
C (2500)

Co (500)
T(450)

V

S. typhi D1/01
(ACCoTNx)

E. coli C600
(Nx)

E. coli C600

[pD1/01]

(ACCoTNx)

0.39 × 10-5

A (1800)

C (1500)

Co (25θ)

T (250)

E. coli C600

[pD1/01]
(ACCoTNx)

S. typhi B72
(Sensitive)

S. typhi B72
[pD1/01]
(ACCoT)

0.48 × 10-7

A (1800)

C (1500)

Co (25θ)

T (250)

A=ampicillin, C=chloramphenicol, Co=Cotrimoxazole, T=tetracycline, Nx=nalidixic acid,p=plasmid

In another experiment, the S. typhi strain D1/01, having the resistance pattern of ACCoTNx, transferred the ACCoT-
resistance to the antibiotic sensitive S. typhi strain through E. coli C600, indicating the non-transferability of Nx-
resistance from D1/01 strain (Table 1).

Transfer of Resistance from E. coli, K. pneumoniae and P. vulgaris to S. typhi

In this study, the MDR E. coli, K. pneumoniae and P. vulgaris strains transferred ACCoT-resistance to the recipient
strains (Table 2).



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