EXTENDED-SPECTRUM BETA-LACTAMASE-PRODUCING KLEBSIELLA-PNEUMONIAE STRAINS CAUSING NOSOCOMIAL OUTBREAKS OF INFECTION IN THE UNITED-KINGDOM

Representative isolates from 10 distinct extended-spectrum beta-lactam ase-producing strains of Klebsiella pneumoniae that caused hospital ou tbreaks in the United Kingdom from 1991 to 1994 were examined for rela tionships between their enzymes and plasmids. The beta-lactamases were identified by a combination of isoelectric focusing and gene sequenci ng. SHV-2 beta-lactamase was produced by isolates from four outbreaks, SHV-5 was involved in three, and SHV-4, TEM-15: and TEM-26 were invol ved in one outbreak each. All of the extended-spectrum p-lactamases we re encoded by self-transmissible plasmids, with sizes ranging from abo ut 70 to 160 kb. No similarities between the restriction digest patter ns of the extended-spectrum beta-lactamase-encoding plasmids were dete cted, except to some extent between those that produced TEM-15 and TEM -26. Thus, outbreaks of hospital infection with these organisms in the United Kingdom from 1991 to 1994 involved distinct organisms and resi stance plasmids and appeared to be unrelated.