Response of Campylobacter jejuni to combinations of ferrous sulphate and cadmium chloride |
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| Authors: | NJ Stern SU Kazmi BS Roberson† K Ono‡ BJ Juven§ |
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| Institution: | United States Department of Agriculture, Agricultural Research Service, Richard B. Russell Agricultural Research Center, Athens, GA 30613, USA;*University of Karachi, Pakisatan;†University of Maryland, College Park;‡Agricultural Research Service, Beltsville, MD, USA;§Agricultural Research Organization, Bet Dagan, Israel |
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| Abstract: | On Mueller Hinton (MH) agar, Campylobacter jejuni showed 20.0 and 30.9mm zones of inhibition surrounding discs impregnated with 2.5 and 20 μg CdCl2 respectively. The minimal inhibitory concentration (MIC) ranged from 0.64 to 3.2 μg CdCl2/ml of MH agar for four C. jejuni strains. In the presence of 23 μg FeSO4/ml of MH the MIC increased to a range of 1.5–5.4 μg CdCl2/ml of MH. Moreover, the numbers of colonies present on MH supplemented with FeSO4 were greater than on MH without iron. The growth response of C. jejuni in the presence of 0.025% (w/v) FeSO4 in MH broth was increased about 10000 fold in three of four strains when compared with the growth in unsupplemented MH broth. Zones of inhibition surrounding 20 μg discs of CdCl2 were 50.6 and 24.4 mm on MH and Campy-BAP media respectively, with cells grown on MH. These results suggest that the blood-containing medium 'neutralized' the biocidal influence of the CdCl2. In comparison, C. jejuni inoculum from fluid thioglycollate (FT) medium showed smaller zones of inhibition. These decreased from 34.9 mm on MH agar to 19.6 mm on Campy-BAP agar, suggesting that components in the FT growth medium ameliorated the toxic influence of CdCl2. Atomic absorption spectroscopy analysis indicated mean values (mg/100 g dry weight) of selected metals bound by C. jejuni as: Cu, 10.4; Mg, 146; Na, 2385; Fe, 45.1; Zn, 13.0; and K, 172. |
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