Clostridium difficile infection in the community: a zoonotic disease?

Clostridium difficile infections (CDIs) are traditionally seen in elderly and hospitalized patients who have used antibiotic therapy. In the community, CDIs requiring a visit to a general practitioner are increasingly occurring among young and relatively healthy individuals without known predisposing factors. C. difficile is also found as a commensal or pathogen in the intestinal tracts of most mammals, and various birds and reptiles. In the environment, including soil and water, C. difficile may be ubiquitous; however, this is based on limited evidence. Food products such as (processed) meat, fish and vegetables can also contain C. difficile, but studies conducted in Europe report lower prevalence rates than in North America. Absolute counts of toxigenic C. difficile in the environment and food are low, however the exact infectious dose is unknown. To date, direct transmission of C. difficile from animals, food or the environment to humans has not been proven, although similar PCR ribotypes are found. We therefore believe that the overall epidemiology of human CDI is not driven by amplification in animals or other sources. As no outbreaks of CDI have been reported among humans in the community, host factors that increase vulnerability to CDI might be of more importance than increased exposure to C. difficile. Conversely, emerging C. difficile ribotype 078 is found in high numbers in piglets, calves, and their immediate environment. Although there is no direct evidence proving transmission to humans, circumstantial evidence points towards a zoonotic potential of this type. In future emerging PCR ribotypes, zoonotic potential needs to be considered.     

What Is the Current Role of Algorithmic Approaches for Diagnosis of Clostridium difficile Infection?

With the recognition of several serious outbreaks of Clostridium difficile infection in the industrialized world coupled with the development of new testing technologies for detection of this organism, there has been renewed interest in the laboratory diagnosis of C. difficile infection. Two factors seem to have driven much of this interest. First, the recognition that immunoassays for detection of C. difficile toxins A and B, for many years the most widely used tests for C. difficile infection diagnosis, were perhaps not as sensitive as previously believed at a time when attributed deaths to C. difficile infections were showing a remarkable rise. Second, the availability of FDA-approved commercial and laboratory-developed PCR assays which could detect toxigenic strains of C. difficile provided a novel and promising testing approach for diagnosing this infection. In this point-counterpoint on the laboratory diagnosis of C. difficile infection, we have asked two experts in C. difficile infection diagnosis, Ferric Fang, who has recently published two articles in the Journal of Clinical Microbiology advocating the use of PCR as a standalone test (see this author''s references 12 and 28), and Mark Wilcox, who played a key role in developing the IDSA/SHEA guidelines on Clostridium difficile infection (see Wilcox and Planche''s reference 1), along with his colleague, Tim Planche, to address the following question: what is the current role of algorithmic approaches to the diagnosis of C. difficile infection?     

Detecting Clostridium difficile Spores from Inanimate Surfaces of the Hospital Environment: Which Method Is Best?

The recovery of Clostridium difficile spores from hospital surfaces was assessed using rayon swabs, flocked swabs, and contact plates. The contact plate method was less laborious, achieved higher recovery percentages, and detected spores at lower inocula than swabs. Rayon swabs were the least efficient method. However, further studies are required in health care settings.     

The undiagnosed cases of Clostridium difficile infection in a whole nation: where is the problem?

Underdiagnosis of Clostridium difficile infection (CDI) because of lack of clinical suspicion or the use of non-sensitive diagnostic techniques is a known problem whose real magnitude has not yet been quantified. In order to estimate the extent of this underdiagnosis, we performed C. difficile cultures on all unformed stool specimens sent—irrespective of the type of request—to a series of laboratories in Spain on a single day. The specimens were cultured, and isolates were characterized at a central reference laboratory. A total of 807 specimens from 730 patients aged ≥2 years were selected from 118 laboratories covering 75.4% of the Spanish population. The estimated rate of hospital-acquired CDI was 2.4 episodes per 1000 admissions or 3.8 episodes per 10 000 patient-days. Only half of the episodes occurred in patients hospitalized for >2 days. Two of every three episodes went undiagnosed or were misdiagnosed, owing to non-sensitive diagnostic tests (19.0%) or lack of clinical suspicion and request (47.6%; mostly young people or non-hospitalized patients). The main ribotypes were 014/020 (20.5%), 001 (18.2%), and 126/078 (18.2%). No ribotype 027 strains were detected. Strains were fully susceptible to metronidazole and vancomycin. CDI was underdiagnosed in diarrhoeic stools in a high proportion of episodes, owing to the use of non-sensitive techniques or lack of clinical suspicion, particularly in people aged <65 years or patients with community-acquired diarrhoea. C. difficile toxins should be routinely sought in unformed stools of any origin sent for microbiological diagnosis. The ribotype 027 clone has not yet disseminated in Spain.     

Diarrhoea in general practice: when should a Clostridium difficile infection be considered? Results of a nested case-control study

Clostridium difficile infections (CDIs) are frequent in hospitals, but also seem to increase in the community. Here, we aim to determine the incidence of CDI in general practice and to evaluate current testing algorithms for CDI. Three Dutch laboratories tested all unformed faeces (12 714) for C. difficile when diagnostic testing (for any enteric pathogen) was requested by a general practitioner (GP). Additionally, a nested case-control study was initiated, including 152 CDI patients and 304 age and sex-matched controls. Patients were compared using weighted multivariable logistic regression. One hundred and ninety-four samples (1.5%) were positive for C. difficile (incidence 0.67/10 000 patient years). This incidence was comparable to that of Salmonella spp. Compared with diarrhoeal controls, CDI was associated with more severe complaints, underlying diseases, antibiotic use and prior hospitalization. In our study, GPs requested a test for C. difficile in 7% of the stool samples, thereby detecting 40% of all CDIs. Dutch national recommendations advise testing for C. difficile when prior antibiotic use or hospitalization is present (18% of samples). If these recommendations were followed, 61% of all CDIs would have been detected. In conclusion, C. difficile is relatively frequent in general practice. Currently, testing for C. difficile is rare and only 40% of CDI in general practice is detected. Following recommendations that are based on traditional risk factors for CDI, would improve detection of CDI.     

Does a rapid diagnosis of Clostridium difficile infection impact on quality of patient management?

A rapid and accurate diagnosis of Clostridium difficile infection (CDI) is essential for patient management and implementation of infection control measures. During a prospective time-series study, we compared the impact of three different diagnostic strategies on patient care. Each strategy was tested during a 3-month period: P1 (diagnosis based on the stool cytotoxicity assay and the toxigenic culture), P2 (diagnosis based on PCR) and P3 (two-step algorithm based on glutamate dehydrogenase detection followed by nucleic acid amplification test). The following criteria were used to assess the quality of patient management: (i) time for result reporting, (ii) frequency of repeat testing within 7 days, (iii) time elapsed between stool collection and beginning of treatment for patients with CDI, and (iv) frequency of empirical treatment for patients without CDI. Of 1122 stool samples (P1 n = 359, P2 n = 374, P3 n = 389), 36 (10.0%), 47 (12.3%) and 48 (12.3%) were positive for C. difficile during P1, P2 and P3, respectively. The time for reporting of a positive or a negative result was significantly shorter and the frequency of redundant stool samples within 7 days was lower during P2 and P3 than during P1. Patients with CDI were specifically treated with vancomycin or metronidazole earlier during P2 and P3 than patients from P1 (0.5 ± 0.5 days and 1.0 ± 1.8 days vs. 2.0 ± 1.7 days). The empirical therapy among patients without CDI decreased from 13.6% during P1 to 6.4% during P2 and 5.6% during P3. A rapid CDI diagnosis impacts positively on patient care.     

Role of fecal Clostridium difficile load in discrepancies between toxin tests and PCR: is quantitation the next step in C. difficile testing?

Direct tests for Clostridium difficile are 30–50?% more sensitive than tests for C. difficile toxins but the reasons for this discrepancy are incompletely understood. In addition to toxin degradation and strain differences, we hypothesized that C. difficile concentration could be important in determining whether toxins are detected in fecal samples. We performed standard curves on an FDA-approved real-time PCR test for the C. difficile tcdB gene (Xpert C. difficile/Epi, Cepheid) during a prospective comparison of a toxin immunoassay (Meridian Premier), PCR and toxigenic culture. Immunoassay-negative, PCR-positive samples were retested with a cell cytotoxin assay (TechLab). Among 107 PCR-positive samples, 46 (43.0?%) had toxins detected by immunoassay and an additional 18 (16.8?%) had toxin detected by the cytotoxin assay yielding 64 (59.8?%) toxin-positive and 43 (40.2?%) toxin-negative samples. Overall, toxin-negative samples with C. difficile had 10¹–10⁴ fewer DNA copies than toxin-positive samples and most discrepancies between toxin tests and PCR were associated with a significant difference in C. difficile quantity. Of the toxin-positive samples, 95?% had ≥4.1 log₁₀ C. difficile tcdB DNA copies/mL; 52?% of immunoassay-negative samples and 70?% of immunoassay and cytotoxin negative samples had <4.1 log₁₀ C. difficile tcdB DNA copies/mL. These findings suggest that fecal C. difficile concentration is a major determinant of toxin detection and C. difficile quantitation may add to the diagnostic value of existing test methods. Future studies are needed to validate the utility of quantitation and determine the significance of low concentrations of C. difficile in the absence of detectable toxin.     

Epidemiology of breast cancer: an environmental disease?Note

Breast cancer is the leading cancer site in women, both in the developed and the developing world. Incidence rates are increasing in many countries, although, in some, mortality may be stable or slightly decreasing. Geographical differences exist, with high rates of disease in North America, North Europe and Oceania, intermediate rates in South and Central America as well as South and East Europe, and low rates in Africa and Asia. Most of the literature reports that genetic inherited factors account for less than 5% of cases, although some authors advance higher figures, up to about 10%. Risk factors for breast cancer are related to the reproductive life of women: early menarche, nulliparity or late age at first birth, late menopause, diet and physical exercise, as well as hormonal factors, be they endogenous (high levels of free or not bound to SHBG estrogens) or exogenous (long-term use of oral contraceptives or menopausal hormone replacement). The present review does not aim to be exhaustive and fully comprehensive, or to present in detail domains currently well known and accepted by all. On the contrary, it modestly wishes to highlight potentially controversial conditions which could in the future be recognized as new risk factors.     

Two Serious Cases of Infection with Clostridium celatum after 40 Years in Hiding?

Clostridium celatum [ce.la''tum. L. adj. celatum hidden] has been known since 1974, when it was isolated from human feces. In 40 years, no association with human infection has been reported. In this work, we present two serious cases of infection with the anaerobic Gram-positive rod Clostridium celatum.     

High in vitro activity of fidaxomicin against Clostridium difficile isolates from a university teaching hospital in China

Background

Clostridium difficile infection (CDI) is a significant cause of morbidity and mortality in both the acute care setting and the wider healthcare system. The purpose of this study was to evaluate the in vitro activity of fidaxomicin against C. difficile isolates from a university teaching hospital in China.

Clostridium difficile Extracytoplasmic Function σ Factor σV Regulates Lysozyme Resistance and Is Necessary for Pathogenesis in the Hamster Model of Infection

Clostridium difficile is a clinically important pathogen and the most common cause of hospital-acquired infectious diarrhea. Expression of the C. difficile gene csfV, which encodes σ^V, an extracytoplasmic function σ factor, is induced by lysozyme, which damages the peptidoglycan of bacteria. Here we show that σ^V is required for lysozyme resistance in C. difficile. Using microarray analysis, we identified the C. difficile genes whose expression is dependent upon σ^V and is induced by lysozyme. Although the peptidoglycan of wild-type C. difficile is intrinsically highly deacetylated, we have found that exposure to lysozyme leads to additional peptidoglycan deacetylation. This lysozyme-induced deacetylation is dependent upon σ^V. Expression of pdaV, which encodes a putative peptidoglycan deacetylase, was able to increase lysozyme resistance of a csfV mutant. The csfV mutant strain is severely attenuated compared to wild-type C. difficile in a hamster model of C. difficile-associated disease. We conclude that the σ^V signal transduction system, which senses the host innate immune defense enzyme lysozyme, is required for lysozyme resistance and is necessary during C. difficile infection.     

Epidemiology of Human Cytomegalovirus (HCMV) in an urban region of Germany: what has changed?

Since the dynamics of transmission of human cytomegalovirus (HCMV) have not been clarified yet, we assessed a possible change in HCMV seroprevalence in Frankfurt am Main, Germany during the past twenty years and tried to detect variables with an impact on epidemiology. Between 1/1/1988 and 10/15/2008, a total of 54443 serum samples were collected for routine diagnostics and analyzed using Enzygnost Anti HCMV-IgG enzyme immunoassay (Siemens/Dade Behring, Marburg, Germany). Two decades, 1/1/1988–12/31/1997 and 1/1/1998–10/15/2008, and several groups (type of health insurance, gender, age, HIV-status) were evaluated to assess changes in seroprevalence. Regarding both decades, the overall age-adjusted prevalence of HIV-negative patients dropped from 63.70% (confidence interval (CI) 95% 63.15–64.25) to 57.25% (CI 95% 56.57–57.93; P < 0.0001). Private health insurance (PHI) patients showed significant lower HCMV seroprevalences than members of obligatory health insurances (OHI) in both decades (1988–1997: PHI = 55.79%, OHI = 64.27%; P < 0.0001; 1998–1908: PHI = 47.02%, OHI = 58.74%; P < 0.0001). Furthermore, comparing the two decades, there was generally a gender-specific statistically significant decrease in HCMV seroprevalence for males (63.54–55.54%) and females (63.83–58.73%) as well as for members of PHI and OHI (PHI males: 57.59% to 47.19%, PHI females 54.10–46.80%; OHI males: 64.00–57.06%, OHI females 64.50–60.11%). Also, while female HIV-positive patients showed significant difference in HCMV seroprevalence between the two decades (83.17 and 87.80%, P = 0.023), there was no significant difference in male patients with HIV (88.76 and 87.32% in the first and second decade, respectively (P = 0.196). The cumulative HCMV prevalence of all HIV-negative patients tested in the past 20 years demonstrates a biphasic, age-related rise of HCMV seroprevalence throughout all age-groups. The seroprevalence of HCMV has declined between 1988–1997 and 1998–2008 in Frankfurt am Main, Germany. The decline varied between different age-groups. HCMV prevalence correlates with the type of health insurance, gender, age, and HIV-status.