Lebrun M, de Repentigny J, Mathieu L G
Can J Microbiol. 1978 Feb;24(2):154-61.
We have studied interactions between Staphylococcus aureus and Pseudomonas aeruginosa in the absence and the presence of four different antimicrobials in mixed cultures and experimental infections. These two bacterial species, in addition to having different properties, are known to be opportunistic pathogens often present in human microflora. Two main aspects have been investigated and they are related to modifications in two species affecting their equilibrium in the mixed bacterial population and also their pathogenicity markers. Our results indicate that individual growth of S. aureus and P. aeruginosa is not modified in vitro in mixed cultures in the absence of antimicrobials; in vivo, in mouse peritoneal cavity, there is a synergism favorable to S. aureus. In the presence of rifamycin SV and three cell wall inhibitors, pencillin G,D-cycloserine, and vancomycin, we have observed that P. aeruginosa protected S. aureus against the inhibitory effect of these antimicrobials in vitro and in vivo. Such results were obtained in different conditions of culture, stationary, shaken, and in special apparatuses, an "Ecologen" and a "Chemostat." When any one of the antimicrobials was allowed to be in contact for 6 to 8 h with P. aeruginosa cells in a culture, we observed a decrease in their inhibitory effects against S. aureus. These results were supported by microscopical observation. It seems that the inhibitory effects of the antimicrobials have hindered the formation of toxic products of S. aureus, e.g., alpha toxin, and that it was not restored in the presence of P. aeruginosa. Conversely, P. aeruginosa remained apparently unchanged through all these experiments. Our observations may imply that the inhibitory effect of an antimicrobial towards a bacterial species may be significantly decreased in the presence of another species, sometimes present in human microflora.
我们研究了在混合培养物和实验性感染中，金黄色葡萄球菌和铜绿假单胞菌在不存在和存在四种不同抗菌药物的情况下的相互作用。这两种细菌除了具有不同特性外，还是人类微生物群中常见的机会致病菌。我们研究了两个主要方面，它们与两种细菌的变化有关，这些变化影响它们在混合细菌群体中的平衡以及它们的致病性标志物。我们 的结果表明，在没有抗菌药物的情况下，金黄色葡萄球菌和铜绿假单胞菌在混合培养物中的个体生长在体外没有改变；在体内，在小鼠腹腔中，存在有利于金黄色葡萄球菌的协同作用。在利福霉素SV和三种细胞壁抑制剂青霉素G、D-环丝氨酸和万古霉素存在的情况下，我们观察到铜绿假单胞菌在体外和体内保护金黄色葡萄球菌免受这些抗菌药物的抑制作用。这些结果是在不同的培养条件下获得的，包括静置、振荡培养，以及在特殊仪器“生态培养器”和“恒化器”中。当任何一种抗菌药物在培养物中与铜绿假单胞菌细胞接触6至8小时时，我们观察到它们对金黄色葡萄球菌的抑制作用减弱。这些结果得到了显微镜观察的支持。似乎抗菌药物的抑制作用阻碍了金黄色葡萄球菌有毒产物如α毒素的形成，并且在铜绿假单胞菌存在的情况下这种抑制作用没有恢复。相反，在所有这些实验中铜绿假单胞菌似乎保持不变。我们的观察结果可能意味着在另一种有时存在于人类微生物群中的细菌存在的情况下，一种抗菌药物对某一细菌物种的抑制作用可能会显著降低。
