Outbreaks of hospital infection in southwest England caused by gentamicin-resistant Serratia marcescens.

Five geographically separate outbreaks of hospital acquired infection caused by gentamicin-resistant strains of Serratia marcescens occurred in the period October 1977 to January 1980 in southwest England. The patients affected were in wards for general or urological surgery, or in neurosurgical, cardiothoracic or general intensive therapy units. Asymptomatic colonization was more common than symptomatic infection, although deaths and serious infections occurred. Control of spread of the bacteria proved difficult. Most strains were resistant to many currently available antibiotics besides gentamicin; only one strain became resistant to amikacin. Representative isolates where characterized by O serotype, bacteriophage type, antibiotic sensitivity pattern, production of beta-lactamases and amino-glycoside-aminocyclitol (ACAG)-modifying enzymes, and plasmid visualization. Plasmid studies provided information that complemented conventional typing methods in determining epidemiological relationships among the outbreaks.