Adherence of multiresistant strains of Klebsiella pneumoniae to cerebrospinal fluid shunts: correlation with plasmid content

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Abstract
A nosocomial multiresistant Klebsiella pneumoniae strain (KMD01) isolated from a patient with an infected ventriculoperitoneal (V-P) shunt was found to contain three plasmids of mol. wts (106) c. 85, 50 and 2·4. A derivative isogenic strain (KMD11) carrying only the plasmids of mol. wts (106) 50 and 2·4 was obtained spontaneously by plating the parent strain. The absence of the plasmid of mol. wt 85×106 in strain KMD11 correlated with an increased adherence to V-P catheters and glass surfaces, as well as autoagglutination in minimal medium. Bacterial cells containing the whole set of plasmids (strain KMD01) also showed the incorporation into the outer membrane of a new polypeptide (mol. wt, c. 41×103), when grown in minimal medium. The presence of this polypeptide correlated with absence of autoagglutination, as shown by strain KMD01 under these cultural conditions. These data suggest that the cell-surface characteristics in K. pneumoniae may be affected by the plasmid content of the strain. Since nosocomial strains of K. pneumoniae usually contain one or more plasmids, and strains easily exchange these extrachromosomal elements, it seems reasonable to speculate that new variants with higher V-P shunt colonisation effectiveness, like the one described in this work, may also evolve in nature.