Biotypes of Klebsiella pneumoniae (sensu lato) and Enterobacter aerogenes characterised by differential substrate metabolism: application of the technique

Abstract

A biochemical typing method is described for Klebsiella pneumoniae (sensu lato) and Enterobacter aerogenes. The technique depends on differences in metabolism of five carbon substrates--glycerol, inositol, lactose, glucose, and xylose--at two concentrations. Reproducibility is satisfactory and is monitored by the incorporation of control klebsiellae of known biotype. The method has been used for 12 months in the surveillance of urinary tract colonisation in this hospital. Gut carriage of klebsiellae, implicated by several workers as a source of infection, was common among staff and new admissions. Many biotypes were represented which were sensitive to most antibiotic except ampicillin. Klebsiellae, all multiply resistant, were isolated most frequently from urine specimens in two orthopaedic wards. In a longitudinal study in these wards, a sequential dominance in urinary tract colonisation by two klebsiella biotypes was shown, which suggested the presence of cross infection or an environmental reservoir. Confirmatory evidence was obtained from capsular serotypes and R-factor studies.