Increased environmental sample area and recovery of Clostridium difficile spores from hospital surfaces by quantitative PCR and enrichment culture

A genomic survey of Clostridioides difficile isolates from hospitalized patients in Melbourne, Australia

IMPORTANCE

There has been a decrease in healthcare-associated Clostridioides difficile infection in Australia, but an increase in the genetic diversity of infecting strains, and an increase in community-associated cases. Here, we studied the genetic relatedness of C. difficile isolated from patients at a major hospital in Melbourne, Australia. Diverse ribotypes were detected, including those associated with community and environmental sources. Some types of isolates were more likely to carry antimicrobial resistance determinants, and many of these were associated with mobile genetic elements. These results correlate with those of other recent investigations, supporting the observed increase in genetic diversity and prevalence of community-associated C. difficile, and consequently the importance of sources of transmission other than symptomatic patients. Thus, they reinforce the importance of surveillance for in both hospital and community settings, including asymptomatic carriage, food, animals, and other environmental sources to identify and circumvent important sources of C. difficile transmission.

Prevalence, Antimicrobial Resistance and Toxin-Encoding Genes of Clostridioides difficile from Environmental Sources Contaminated by Feces

Clostridioides difficile (C. difficile) is the most common pathogen causing antibiotic-associated intestinal diseases in humans and some animal species, but it can also be present in various environments outside hospitals. Thus, the objective of this study was to investigate the presence and the characteristics of toxin-encoding genes and antimicrobial resistance of C. difficile isolates from different environmental sources. C. difficile was found in 32 out of 81 samples (39.50%) after selective enrichment of spore-forming bacteria and in 45 samples (55.56%) using a TaqMan-based qPCR assay. A total of 169 C. difficile isolates were recovered from those 32 C. difficile-positive environmental samples. The majority of environmental C. difficile isolates were toxigenic, with many (88.75%) positive for tcdA and tcdB. Seventy-four isolates (43.78%) were positive for binary toxins, cdtA and cdtB, and 19 isolates were non-toxigenic. All the environmental C. difficile isolates were susceptible to vancomycin and metronidazole, and most isolates were resistant to ciprofloxacin (66.86%) and clindamycin (46.15%), followed by moxifloxacin (13.02%) and tetracycline (4.73%). Seventy-five isolates (44.38%) showed resistance to at least two of the tested antimicrobials. C. difficile strains are commonly present in various environmental sources contaminated by feces and could be a potential source of community-associated C. difficile infections.

A comparison of culture methods and polymerase chain reaction in detecting Clostridioides difficile from hospital surfaces

Introduction. Environmental surveillance for Clostridioides difficile is challenging. There are no internationally agreed recommendations on which method should be used when environmental surveillance is undertaken.Aim. To compare the detection of C. difficile by RT-PCR to culture-based methods and to determine which is more sensitive and specific in the clinical environment.Methods. Forty-four near-patient areas of C. difficile-positive patients were sampled using contact plates and moistened flocked swabs.Results. Detection using moistened flocked swabs followed by RT-PCR or culture detected more C. difficile than contact plates. The sensitivity and specificity of a RT-PCR assay for tcdB compared to the culture methods was 76 and 91 %, respectively.Conclusion. Despite the lower sensitivity and specificity, RT-PCR could potentially offer a more rapid and practical alternative.

Impact of Oral Metronidazole, Vancomycin, and Fidaxomicin on Host Shedding and Environmental Contamination with Clostridioides difficile

OBJECTIVES

Shedding of Clostridioides difficile spores from infected individuals contaminates the hospital environment and contributes to infection transmission. We assessed whether antibiotic selection impacts C. difficile shedding and contamination of the hospital environment.

METHODS

In this prospective, unblinded, randomized controlled trial of hospitalized adults with C. difficile infection, subjects were randomized 1:1:1 to receive fidaxomicin, oral vancomycin, or metronidazole. The primary outcome was change in environmental contamination rate while on treatment. Secondary outcomes included stool shedding, total burden of contamination, and molecular relatedness of stool versus environmental C. difficile isolates.

RESULTS

33 patients were enrolled and 31 (94%) completed the study. Fidaxomicin (-0.36 log10 CFU/day, 95% CI -0.52 to -0.19, p<0.01) and vancomycin (-0.17 log10 CFU/day, 95% CI -0.34 to -0.01, p=0.05) were associated with more rapid decline in C. difficile shedding compared to metronidazole (-0.01 log10 CFU/day, 95% CI -0.10 to +0.08). Both vancomycin (6.3%, 95% CI 4.7-8.3%) and fidaxomicin (13.1%, 95% CI 10.7-15.9%) were associated with lower rates of environmental contamination than metronidazole (21.4%, 95% CI 18.0-25.2%). When specifically modeling within-subject change over time, fidaxomicin (aOR 0.83, 95% CI 0.70-0.99, p=0.04) was associated with more rapid decline in environmental contamination than vancomycin or metronidazole. Overall, 207 of 233 (88.8%) of environmental C. difficile isolates matched subject stool isolates by ribotyping, without significant difference by treatment.

CONCLUSIONS

Fidaxomicin, and to a lesser extent vancomycin, reduces C. difficile shedding and contamination of the hospital environment relative to metronidazole. Treatment choice may play a role in reducing healthcare-associated C. difficile transmission.

Comparative Study of Clostridium difficile Clinical Detection Methods in Patients with Diarrhoea

Objectives

The aim of this study was to evaluate the clinical application of three methods for detecting Clostridium difficile in fecal samples.

Methods

One hundred and fifty fecal specimens were collected and tested for C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay.

Results

Of 150 specimens, 26 carried both A and B toxin genes, and none of the samples were positive for the binary toxin gene. Toxin-producing C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay. C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay.

Conclusion

The VIDAS GDH assay is useful for initial screening of C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay.

Development of a rapid-viability PCR method for detection of Clostridioides difficile spores from environmental samples

Clostridioides difficile is a common pathogen that is well known to survive for extended periods of time on environmental healthcare surfaces from fecal contamination. During epidemiological investigations of healthcare-associated infections, it is important to be able to detect whether or not there are viable spores of C. difficile on surfaces. Current methods to detect C. difficile can take up to 7 days for culture and in the case of detection by PCR, viability of the spores cannot be ascertained. Prevention of C. difficile infection in healthcare settings includes adequate cleaning and disinfection of environmental surfaces which increases the likelihood of detecting dead organisms from an environmental sample during an investigation. In this study, we were able to adapt a rapid-viability PCR (RV-PCR) method, first developed for detection of viable Bacillus anthracis spores, for the detection of viable C. difficile spores. RV-PCR uses the change in cycle threshold after incubation to confirm the presence of live organisms. Using this modified method we were able to detect viable C. difficile after 22 h of anaerobic incubation in Cycloserine Cefoxitin Fructose Broth (CCFB). This method also used bead beating combined with the Maxwell 16 Casework kit for DNA extraction and purification and a real-time duplex PCR assay for toxin B and cdd3 genes to confirm the identity of the C. difficile spores. Spiked environmental sponge-wipes with and without added organic load were tested to determine the limit of detection (LOD). The LOD from spiked environmental sponge-wipe samples was 10⁴ spores/mL but after incubation initial spore levels of 10¹ spores/mL were detected. Use of this method would greatly decrease the amount of time required to detect viable C. difficile spores; incubation of samples is only required for germination (22 h or less) instead of colony formation, which can take up to 7 days. In addition, PCR can then quickly confirm or deny the identity of the organism at the same time it would confirm viability. The presence of viable C. difficile spores could be detected at very low levels within 28 h total compared to the 2 to 10-day process that would be needed for culture, identification and toxin detection.