Correlation of disease severity with fecal toxin levels in patients with Clostridium difficile-associated diarrhea and distribution of PCR ribotypes and toxin yields in vitro of corresponding isolates.

We investigated in vivo and in vitro yields of toxins A and B from and PCR ribotypes of Clostridium difficile isolates from 164 patients with differing severities of C. difficile-associated diarrhea (CDAD) (patients were grouped as follows: <3 loose stools per day, n = 45; 3 to 10 per day, n = 97; >10 per day, n = 22). The median fecal toxin levels in each group were 0.5, 6.8, and 149 U/g feces (P < 0.001), respectively. Patients with severe diarrhea also had more-frequent occurrence of blood in stool and vomiting, but there was no association with fecal toxin levels per se. There was no correlation between fecal toxin level and toxin yield in vitro for the corresponding C. difficile isolate or between its PCR ribotype and disease severity. A broad range of toxin yields among isolates belonging to major PCR ribotypes indicated a presence of many subtypes. We hypothesize that bacterial and host factors that affect C. difficile toxin levels in feces are important determinants of symptoms in CDAD patients. An inverse correlation between toxin yield and spore count (r = 0.66) in stationary-phase cultures supported the notion that toxin production and sporulation represent opposite alternative survival strategies for C. difficile cells facing nutrient shortage.

Epidemiology and molecular characterization of Clostridium difficile strains from patients with diarrhea: low disease incidence and evidence of limited cross-infection in a Swedish teaching hospital.

We prospectively studied the epidemiology of Clostridium difficile-associated diarrhea (CDAD) in a 900-bed hospital over the course of 12 months by PCR-ribotyping of C. difficile isolates. A total of 304 cases were diagnosed, corresponding to an overall incidence of 7/1,000 admissions, with higher rates in nephrology, hematology, and organ transplantation wards (37, 30, and 21/1,000), and 72% were classified as hospital associated (onset in hospital or onset at home but after a hospital stay within 2 months). All 382 isolates from 227 of 304 (75%) patients available for PCR-ribotyping were typeable, yielding 70 PCR-ribotypes. The three most common types comprised 30% of hospital-associated and 34% of community-associated cases, indicating import via admitted patients as a major source of C. difficile strains occurring in the hospital. Of the 227 patients studied, 38% each contributed 2 to 13 fecal samples positive for C. difficile over the course of the study period. Repeat isolates of the same PCR-ribotype as the first isolate were found in 79% of these patients and in 95% of specimens delivered within 30 days, compared to 63% of those obtained at 31 to 204 days. Nosocomial acquisition of CDAD, defined as the proportion of cases sharing C. difficile type and admitted to the same ward within 2 or 12 months, was 20% and 32% of hospital-associated cases and 14% and 23% of all cases, respectively. Thus, most CDAD cases diagnosed over the course of the study period, including those associated with hospitalization, appeared to be caused by endogenous C. difficile strains rather than by strains truly being acquired in the hospital.

Limited value of routine microbiological diagnostics in patients hospitalized for community-acquired pneumonia.

Current guidelines recommend microbiological diagnostic procedures as a part of the management of patients hospitalized for community-acquired pneumonia (CAP), but the value of such efforts has been questioned. Patients hospitalized for CAP were studied retrospectively, focusing on the use of aetiological diagnostic methods and their clinical impact. Adult patients, without known human immunodeficiency virus infection, admitted to hospital for CAP during 12 months, were evaluated with regard to the importance of aetiological diagnosis for tailoring antibiotic therapy, antibiotic-associated diarrhoea, Clostridium difficile disease, length of hospital stay and mortality. Of the 605 studied patients, 482 (80%) were subjected to Mycoplasma pneumoniae and/or respiratory virus serology and/or cultures of blood and/or sputum. They had a better prognosis than patients not subjected to microbiological diagnostics (mortality within 3 months was 9% vs 24%, p = 0.001), apparently reflecting differences in general health (e.g. less dementia diagnosis) but not the outcome of diagnostics. A presumptive aetiology was obtained only in 132 of the 482 patients, Streptococcus pneumoniae and M. pneumoniae being the most common agents (in 49 and 36 patients, respectively). Establishing an aetiological diagnosis had no impact on the number of in-hospital changes of therapy, on the proportion of new regimens having a narrower antimicrobial spectrum than the initial one or on the outcome. Therapy was changed to a drug directed specifically against the identified pathogen in only 16 out of these 132 patients and again without any overall improvement in the outcome variables. In a setting with a low frequency of antibiotic-resistant respiratory tract pathogens current routine microbiological diagnostics were found to be of limited value for the clinical management of patients hospitalized for CAP. Improved diagnostics in CAP are urgently needed, as establishing an aetiological diagnosis carries a potential for optimizing the antibiotic therapy.