To understand the epidemiology, risks, and management of Clostridium difficile -associated disease (CDAD) and to establish and evaluate reliable methods of surveillance.

Case finding was done by daily ward and laboratory rounds. The criteria for CDAD diagnosis were: at least four unformed stools per day for 2 days and a positive culture or cytotoxin for C difficile, or positive endoscopy or autopsy for pseudomembranes.

The surveillance covered all patients from 1982 through 1991 in the 820-bed Minneapolis Veterans Affairs Medical Center.

The criteria were met by 908 patients. Medical service patients numbered 488; surgical patients, 420. Frequencies ranged from a high of 149 cases in 1982 to a low of 50 cases in 1989.

Stool specimens were obtained on 898 (99%) of the 908 CDAD patients. Stools were culture-positive in 864 (96%) of 898, cytotoxin-positive in 569 (63%) of 898. Endoscopy was performed on 196 (22%) of the 908 patients, and 80 (41%) of 196 patients had pseudomembranes. Ten (1%) of the 908 patients were diagnosed by endoscopy without a stool specimen, or at autopsy. No treatment was needed for 135 (15%) of the 908 CDAD patients, and 19 (2%) of the 908 died before treatment was started. Oral metronidazole was the treatment for 632 (70%) of 908 patients (1% intolerance, 2% failure, 7% relapse) and oral vancomycin was given to 122 (13%) of 908 patients (1% intolerance, 1% failure, 10% relapse). Twelve patients had pseudomembranous colitis at autopsy, and it was the primary cause of death in 5 (0.6%) of 908.

CDAD usually responds to oral metronidazole or vancomycin but is nonetheless responsible for a high morbidity and occasional mortality in patients even when the diagnosis and treatment are pursued aggressively.

To evaluate the endemicity and epidemiology of toxigenic Clostridium difficile in a sustained outbreak of antibiotic-associated diarrhea.

University-affiliated, 465-bed tertiary care teaching hospital with adjacent cancer clinic in Hamilton, Ontario.

From August 8, 1991, through August 31, 1993, a total of 187 cases were investigated for epidemiologic analysis of toxigenic C difficile from stool cultures, to identify the endemic clone(s). To assess the nature of contamination, cultures of inanimate surfaces in the patient environment from the four most affected units (medical teaching, nonteaching medical, hematologic oncology, and the intensive care unit) were processed for C difficile. The 229 clinical strains and 24 environmental strains isolated were typed by numerical analysis of SDS-PAGE protein patterns.

A majority (81%) of cases in the epidemiologic analysis were associated with a toxigenic electrophoretic (EP) type 1 C difficile that was identical to the strain first isolated from an index case that occurred 18 months before the start of this study. Culture and typing of the C difficile strains from the inanimate surfaces in the four most affected units showed that the patient environment was contaminated with the toxigenic EP type 1 organism. Six other strains that occurred infrequently among cases also were found in the environment.

A single predominant toxigenic clone has been implicated in a sustained outbreak of antibiotic-associated diarrhea that affected elderly patients. The “endemic” clone transmitted for the 25-month study period was linked to an index case shedding a toxigenic EP type 1 strain that occurred 21 months prior to the initial outbreak on the medical teaching unit. The patient environment in the affected units was found to be contaminated with the same clone, possibly due to shedding of organisms by fecally incontinent symptomatic patients. The extrinsic factors contributing to the endemic transmission of this one clone still are not well understood

To investigate a cluster of Serratia odorifera in a cardiothoracic surgery unit (CTSU) and to evaluate the applicability of three typing methods for this species.

During a surveillance surgical wound study, S odorifera was isolated from two patients in the CTSU. The patients' hospital charts were reviewed for the details of surgery and for common personnel, procedures, or medications. Cultures were obtained of water, soap, and unit dose medications from the CTSU, the operating room, and the surgical intensive care unit. The isolates' antibiograms, biotypes (Vitek identification card and API 20E), and patterns of chromosomal DNA (chrDNA) by pulsed-field gel electrophoresis (PFGE) were examined. S odorifera isolates from our organism collection were used as controls.

A 900-bed university hospital with a 22-bed CISU.

ChrDNA patterns of isolates from the two patients were identical, suggesting a possible nosocomial source. However, no source of organisms or mode of transmission was identified. Neither biotype nor antibiogram were useful for epidemiologically typing S odorifera, and PFGE was necessary to discriminate among isolates.

Although rarely isolated, S odorifera and other non- marcescens Serratia species may cause nosocomial outbreaks. PFGE of chrDNA seems to be a reliable method for epidemiologically typing this species.