Simultaneous outbreaks of two strains of toxigenic Clostridium difficile in a general hospital

Abstract We report an outbreak of Clostridium difficile -associated disease (CDAD) in a large Dublin hospital. From January to June 1995, inclusive, 139 patients were affected; the mean age of cases was 68·8 ± 19 years. Clinical information is available for 73 cases identified during the first four months of the outbreak. The majority of patients presented with abrupt onset of watery diarrhoea; however, 19·2% presented with an unexplained pyrexia following a course of antimicrobial therapy and 5·5% presented with a surgical acute abdomen. Twenty patients (27·4%) experienced relapsing disease and seven (9·6%) patients died. Seventy-six percent of cases received a cephalosporin prior to the onset of disease, the highest relative risks occurring with third-generation agents; however, 9·6% of patients affected had not been exposed to antimicrobial therapy in the preceding eight weeks. Pyrolysis mass spectrometry identified two clusters of isolates, representing two strains of C. difficile . There was marked spatial clustering of these strains, with each confined to a separate area of the hospital. Infection control measures and an antibiotic policy were introduced. Throughout the outbreak period the use of the most frequently used cephalosporin in the hospital increased; this was accompanied paradoxically by a reduction in the number of new cases of CDAD.