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A total of 259 clinical isolates of nonrepetitive non-typhi salmonellae (NTS) were examined for antibiotic resistance patterns and plasmid content. The antibiotics used were amoxicillin-clavulanic acid (AMC), ampicillin (AM), aztreonam (ATM), carbenicillin (CB), cefixime (CFM), cefotaxime (CTX), cefoxitin (FOX), ceftazidime (CAZ), ceftriaxone (CRO), chloramphenicol (C), ciprofloxacin (CIP), gentamicin (GM), imipenem (IPM), ofloxacin (OFX), tetracycline (TE), trimethoprim-sulfomethoxazole (SXT). Multi-drug resistant (MDR) strains comprised 19.3% of the total isolates (50/259) and almost all were S. typhimurium (49/50). Fifteen different patterns of resistance was observed, AM/CB/C/AMC/TE and AM/CB/C/AMC/SXT/GM/CTX/CRO/CAZ/CFM/ATM being the most frequent patterns. Twenty-eight out of 50 multiresistant isolates were found to contain at least one plasmid (mean five) and the size of the plasmids ranged between 1.7 and 158 kb. Plasmid profiles of multiresistant NTS strains were heterogenous as 21 different profiles were detected in a total of 28 plasmid-bearing isolates. No direct correlation was established between antibiotic resistance patterns and plasmid profiles.

Through preliminary plate tests, Kluyveromyces marxianus was found to be much more resistant to toxic heavy metals compared to a CUP1R strain of Saccharomyces cerevisiae. Specific growth rate and maximum dry weights affected by increasing metal concentrations were determined to obtain precise patterns of resistance. Metal biosorption was also monitored during the course of growth in synthetic media containing respective metals at 0.5 mM final concentration. Although Zn- and Co-binding was negligible, as much as 90% of silver, 60% of copper, and 65% of cadmium were found to be absorbed by the end of active growth. Analysis of the protein profiles of S. cerevisiae and K. marxianus on metal exposure suggested constitutive production of metallothionein in K. marxianus. Furthermore, a smaller protein synthesized by K. marxianus on induction by silver or cadmium accounts for the high resistance of the organism to these metals.

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Kluyveromyces spp. have been found to be more efficient than a CUPIR strain of S. cerevisiae in heavy metal resistance and accumulation. The present study describes the s&cellular distribution of the accumulated metals (Ag, Cd, Cu) in S. cerevisiae and K. marxianus. Absorption by insoluble cellular material of the metals appears as the main mechanism of metal accumulation in both organisms.