The H. pylori isolates that harbored two or three virulence markers were more resistant to Cla and Mtz. Combined analysis of virulent genotypes and resistance patterns may permit identification of high-risk patients to prevent PU later in life or to avoid antimicrobial treatment failure.

The growth and botulinic toxin production of Clostridium argentinense G 89 HT in co-culture with Pseudomonas mendocina were studied using two culture systems with carbon sources of rapid and slow utilization. Growth with glucose in homogeneous co-culture presented a dual-phase progression, with the toxin produced in the slow-growing phase. The extended 50 h growth period of the second phase at low specific growth rate was attributed to the combined metabolization of glucose and a complex carbon source of the alginate type produced by P. mendocina under strongly reducing conditions. With dextrin, the co-culture grew at the lower specific growth rate (l = 0.03 h -1 ) for a period lasting 80 h. This fully enhanced the production of toxin with a specific toxicity 2.5 times higher than with glucose in a homogeneous system and 10.7 higher than that of C. argentinense G 89 HT single culture. The heterogeneous co-culture obtained with a dialysis membrane physically separating both bacteria (thereby eliminating the metabolic interaction) produced the lowest levels of growth and toxin of all the cases analyzed.