Clostridium difficile Strains from Community-Associated Infections

Abstract

Clostridium difficile isolates from presumed community-associated infections (n ‫؍‬ 92) were characterized by toxinotyping, pulsed-field gel electrophoresis, tcdC and cdtB PCR, and antimicrobial susceptibility. Nine toxinotypes (TOX) and 31 PFGE patterns were identified. TOX 0 (48, 52%), TOX III (18, 20%), and TOX V (9, 10%) were the most common; three isolates were nontoxigenic.Clostridium difficile infection (CDI) is an important cause of health care-associated diarrhea, especially in patients receiving antibiotics. C. difficile also causes diarrhea among patients in community settings (1,6,13,19,20), although diarrheic outpatients are not routinely tested for CDI. Community-associated CDI (CA-CDI) appears to be increasing (3,11,22), but little is known about strains that cause it. We collected and characterized isolates from patients with presumed CA-CDIs.Surveillance for CA-CDI was conducted in 2006 for 3 months at 19 clinical laboratories in nine states participating in the Food-Borne Disease Active Surveillance Network (FoodNet; California, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee). Stool specimens from patients with positive physician-ordered C. difficile toxin tests were stored at Ϫ20°C until medical record review confirmed study eligibility. Presumed CA-CDI was defined as a C. difficile toxin-positive stool specimen from an outpatient (or within 72 h of hospital admission) without a previous positive result in the same laboratory for Ͼ8 weeks or an overnight health care stay in the preceding 3 months. Diagnostic assays varied and included toxin A-only or toxin A and B enzyme immunoassays. The sensitivity and specificity of diagnostic assays were not evaluated.C. difficile toxin-positive stool samples were submitted frozen to the state's public health laboratory or the Durham Veterans Affairs Medical Center laboratory (Durham, NC) for culture. Thawed stool samples were cultured by alcohol shock (12) on anaerobe blood agar plates (BD, Franklin Lakes, NJ), direct inoculation of cycloserine-cefoxitin fructose agar (4), or both and then incubated anaerobically at 35°C for 72 to 96 h.Plates were examined daily for characteristic colonies (4), pcresol odor, and yellow-green fluorescence under UV light. Chopped meat broth (BD) was inoculated with a single colony and shipped to the Centers for Disease Control and Prevention (CDC) for confirmatory identification by the characteristics noted above, a negative indole reaction, and a positive L-prolineaminopeptidase (Remel, Lenexa, KS) reaction. Isolates were characterized by toxinotyping, pulsed-field gel electrophoresis (PFGE), PCR evaluation of tcdC (10) and cdtB (20), and antimicrobial susceptibility testing.Of 175 specimens obtained from patients with presumed CA-CDIs, 162 were cultured; 103 isolates were submitted to the CDC, and 92 were confirmed as C. difficile. The C. difficile recovery rate from 162 toxin-positive stool samples was 57% (range, 29 to 100% by laboratory).Toxinotyping was based on restriction frag...

Diagnosis of Clostridium difficile Infection: an Ongoing Conundrum for Clinicians and for Clinical Laboratories

“…Although C. difficile is the number one cause of hospital-acquired diarrhea, it is not exclusively a nosocomial pathogen (34,192). Numbers of cases of community-acquired and community-associated infection are increasing worldwide; around the world, up to 25% of cases are community acquired, and these patients may not have the traditional risk factors for CDI, such as advanced age, antibiotic exposure, and medications to suppress gastric acid (188,(192)(193)(194)(195). A pilot study was recently conducted whereby whole-genome sequencing (this method is discussed in more detail below) was performed in almost real time to evaluate C. difficile transmission.…”

Clostridium difficileinfection

“…Communityassociated CDI (up to 16.2/100,000 cases 6 ), has been observed in individuals with no previous recent antibiotic exposure (up to 90 days), no hospitalization and few or no co-morbidities. 6,84 Interestingly, one risk factor may be close association with infants less than 2 years of age, likely due to their asymptomatic carriage of C. difficle. 85,86 Another risk factor appears to be residence in a long-term care facility, where it has been demonstrated that anywhere from 9 87 to 50% 88 of the population may be asymptomatically colonized with C. difficile, thus acting as reservoirs of infection.…”

Impact of Strain Type on Detection of Toxigenic Clostridium difficile: Comparison of Molecular Diagnostic and Enzyme Immunoassay Approaches

“…C. difficile isolates are capable of causing, in addition to diarrheal disease, serious syndromes, such as pseudomembranous colitis and toxic megacolon, which may result in death (11,13). This organism is also responsible for increasing numbers of community-acquired infections (14,16). Hypervirulent strains of C. difficile have emerged, including the J strain (9) and 027/ NAP1/BI strain (20), the latter of which has been responsible for a series of hospital outbreaks around the world (10,12,20,22).…”