Effective and Reduced-Cost Modified Selective Medium for Isolation of Clostridium difficile

Abstract

Both for epidemiologic studies and for diagnostic testing, there is a need for effective, economical, and readily available selective media for the culture of Clostridium difficile. We have developed a reduced-cost substitute for cycloserine-cefoxitin-fructose agar (CCFA), which is an effective but expensive selective medium for C. difficile. The modified medium, called C. difficile brucella agar (CDBA), includes an enriched brucella base as a substitute for proteose peptone no. 2, and the concentration of sodium taurocholate has been reduced from 0.1% to 0.05%. To compare the sensitivities and selectivities of CDBA and CCFA, cultures for C. difficile were performed using stool samples from patients with C. difficile-associated disease. CDBA was as sensitive as CCFA for the recovery of C. difficile, with a similar frequency of breakthrough growth of stool microflora (25% versus 31%, respectively). A liquid formulation of the modified medium, termed C. difficile brucella broth (CDBB), stimulated rapid germination and outgrowth of C. difficile spores, at a rate comparable to that in cycloserine-cefoxitin-fructose broth. Our results suggest that CDBA and CDBB are sensitive, selective, and reduced-cost media for the recovery of C. difficile from stool samples.

Comparison of Perirectal versus Rectal Swabs for Detection of Asymptomatic Carriers of Toxigenic Clostridium difficile

“…It was noted whether the swabs had evidence of fecal staining, but all swabs were processed. The swabs were transferred to a Whitley MG1000 anaerobic workstation (Microbiology International, Frederick, MD) and cultured for C. difficile on prereduced cycloserine-cefoxitin-brucella agar containing 0.1% taurocholic acid and lysozyme at 5 mg/ml (CDBA) as previously described (10). The number of colonies was counted.…”

Restriction Map For NK104-NK105 of Nonrepeating Region For tcdB Toxin Gene in Clostridium difficile

“…Equal volumes of stool specimen and absolute ethanol were mixed and incubated at room temperature for 30 min. The alcohol-treated stool specimen was inoculated onto anaerobically reduced cycloserine-cefoxitin fructose agar (CCFA), and it was anaerobically incubated at 37ºC in an anaerobic jar for 48 to 72 h [9]. All bacteria used in this study were identified by odor and colony morphology on CCFA and cell morphology after Gram staining.…”

Effectiveness of an Electrochemically Activated Saline Solution for Disinfection of Hospital Equipment

“…After 10 minutes of contact time, 1 mL of Dey-Engley neutralizer (Remel) was added, and viable organisms were quantified by plating on media selective for each pathogen. 10 Although the complete experiments included only a 10-minute contact time, preliminary experiments with the 3 C. difficile strains did demonstrate equivalent kiUing of spores at 5 and 10 minutes for both bleach and Sterilox HG, respectively. The experiments were repeated 3 times.…”

“…C. difficile spores were prepared as previously described. 10 Ten-microliter aliquots containing ~6 log 10 colony-forming units (CFUs) of the organisms suspended in deionized water with or without simulated organic load containing bovine serum albumin, tryptone, and mucin (0.5 : 5 :0.4% w/v) were spread to cover 1-cm-diameter polystyrene ceU culture wells (nest ceU culture plate, Denville Scientific). After the suspensions air dried, 300 IxL of deionized water, Sterilox HG, or 10% household bleach (Clorox) was added.…”

“…Cultures for C. difficile were processed as previously described. 10 The swabs were also plated onto 5% sheep blood tryptic soy agar plates (Becton Dickinson) to quantify total aerobic and facultative bacteria. A Fisher exact test was used to compare the percentages of positive cultures, and paired t tests were used to compare mean CFUs recovered before versus after application of Sterilox HG.…”