The role of thiamine in Yersinia kristensenii resistance to antibiotics and heavy metals.

The resistance to divalent metal ions, antibiotics and H2O2 was investigated in Yersinia kristensenii strains 13, 15, 18 by performing subcultivations with CdSO4 (20 and 100 mg/L) in nutrient agar (NA) and M9 medium with thiamine. Metal resistance of all three strains in NA was the same and decreased in the following sequence: Ni > Zn = Co > Cd. The chloramphenicol (Cmp) resistance ranged between 32 and 256 mg/L and the H2O2 sensitivity was very low or even zero.

Influence of cadmium on resistance to antibiotics in salmonellae isolated from pigs.

Repeated cultivations (4 passages) of salmonellae (18 strains) resistant to cadmium, streptomycin and beta-lactam antibiotics in Müller-Hinton Broth (MHB) and Mac-Conkey Broth (MCB) without and with CdSO4 (2, 20 and 100 mg/L) showed a higher toxic effect of cadmium in MCB. The strains survived at CdSO4 100 mg/L in MHB for four transfers, in MCB only a single transfer. In dependence on the medium used and amount of metal added, the increase of resistance to antibiotics was different.

Relation between resistance to beta-lactam antibiotics and cadmium in salmonellae isolated from pigs.

Of 50 Salmonella species isolated from pigs, 30 were resistant to cadmium and 18 of these also to azlocillin. The azlocillin-resistant isolates were resistant to cadmium at 80-500 mg/L CdSO4. A broader spectrum of resistance to azlocillin, ampicillin and cephazolin was found in strains resistant to < 200 mg/L CdSO4.

Conjugation in lysogenic, multiple-drug resistant, nosocomial strains of Pseudomonas aeruginosa producing a hemolytic toxin.

From incubators and children in a premature-born unit, a number of red-pigmented Ps. aeruginosa strains, resistant to kanamycin, streptomycin and lividomycin and producing haemolytic toxin II, were isolated and investigated for transfer of resistance in mixed cultures. Streptomycin, kanamycin and lividomycin resistance was co-transferred, from some strains, together with the ability of toxin production.