Resistotyping as a new epidemiological marker for Klebsiella pneumoniae

Resistogram typing was established with the help of 30 randomly chosen clinical isolates of K. pneumoniae using sodium arsenate, malachite green, boric acid, potassium tellurite, mercuric chloride, antimony potassium tartarate and sodium arsenite. The resistance to these chemicals was designated as A, B, C, D, E, F and G respectively. The technique was then applied to 152 clinical isolates of K. pneumoniae. A total of 35 patterns were obtained. Common patterns were ABEFG and ABFG. There was no clustering of the strains in any of the resistogram patterns as even the commonest pattern had only 10.5 per cent of the strains. When combined with klebocin typing, it provided better discrimination of strains as strains belonging to seven klebocin types could be subdivided into 68 resistogram patterns. The reverse was also possible, i.e., the strains belonging to seven resistogram patterns could be subdivided into 38 klebocin types. The former procedure thus offered better discrimination of the strains.