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D N Gerding

Publications and source records attributed to D N Gerding.

At least 19 recordsLinked to original sources
PubMed2006

Comparative phylogenomics of Clostridium difficile reveals clade specificity and microevolution of hypervirulent strains.

Clostridium difficile is the most frequent cause of nosocomial diarrhea worldwide, and recent reports suggested the emergence of a hypervirulent strain in North America and Europe. In this study, we applied comparative phylogenomics (whole-genome comparisons using DNA microarrays combined with Bayesian phylogenies) to model the phylogeny of C. difficile, including 75 diverse isolates comprising hypervirulent, toxin-variable, and animal strains. The analysis identified four distinct statistically supported clusters comprising a hypervirulent clade, a toxin A(-) B(+) clade, and two clades with human and animal isolates. Genetic differences among clades revealed several genetic islands relating to virulence and niche adaptation, including antibiotic resistance, motility, adhesion, and enteric metabolism. Only 19.7% of genes were shared by all strains, confirming that this enteric species readily undergoes genetic exchange. This study has provided insight into the possible origins of C. difficile and its evolution that may have implications in disease control strategies.

Animals↗
PubMed2001

Fatal pseudomembranous colitis associated with a variant clostridium difficile strain not detected by toxin A immunoassay.

BACKGROUND: Many clinical laboratories use toxin A immunoassays to test for Clostridium difficile. OBJECTIVE: To describe the clinical course of a patient infected with a toxin variant strain of C. difficile that was not detected by toxin A immunoassay; to genetically characterize this strain; and to estimate the number of laboratories that use only toxin A immunoassays. DESIGN: Case report, molecular investigation, and laboratory survey. SETTING: Tertiary care hospital in Chicago, Illinois. PATIENT: An 86-year-old man. MEASUREMENTS: Restriction endonuclease analysis, polymerase chain reaction, and survey of regional clinical laboratories. RESULTS: An elderly hospitalized man died of advanced pseudomembranous colitis. Four stool specimens submitted over a 2-month period had tested negative on toxin A immunoassay, but a strain of C. difficile with a 1.8-kb deletion of the toxin A gene was recovered from each specimen. This strain, identified as restriction endonuclease analysis type CF4, is closely related to a widely disseminated variant, toxinotype VIII. Toxin A immunoassay was the only test being performed for detection of C. difficile at 31 of 67 (46%) regional clinical laboratories. CONCLUSIONS: Toxin A variant strains of C. difficile cause serious disease and are undetectable in clinical laboratories that use only toxin A immunoassays for C. difficile testing.

Aged↗
PubMed2001

Infection of hamsters with epidemiologically important strains of Clostridium difficile.

Five different toxigenic strains of Clostridium difficile of known human epidemiologic importance were tested for virulence in hamsters. Three strains-types B1, J9, and K14-have caused hospital outbreaks. Type Y2 is associated with a high rate of asymptomatic colonization in patients. The fifth strain, type CF2, is a toxin A-negative, toxin B-positive strain implicated in multiple human cases of C. difficile-associated diarrhea. Groups of 10 hamsters per strain were given 1 dose of clindamycin, followed 5 days later with gastric inoculation of 100 cfu of C. difficile. Hamsters given types B1, J9, K14, or Y2 showed 90%-100% colonization (albeit at a slower rate with type Y2) and 100% mortality of colonized animals. Hamsters challenged with type CF2 showed 60% (P= .01) colonization and 30% mortality (P= .0003). The hamster model demonstrated pathogenicity differences between a toxin variant strain and standard toxigenic strains but no significant differences among the standard strains.

Animals↗
PubMed2000

Treatment of Clostridium difficile-associated diarrhea and colitis.

Treatment of C. difficile diarrhea with metronidazole or vancomycin is highly effective at relieving symptoms. The high rate of diarrhea recurrence is concerning, but fortunately most patients respond to a second course of treatment. The problem of vancomycin resistance in hospital organisms has markedly reduced usage of this agent as a first-line treatment for C. difficile diarrhea, leaving metronidazole as the mainstay of treatment in the United States where teicoplanin and fusidic acid are not marketed. It is likely that any new antimicrobial agent used to treat C. difficile will be similarly plagued by a high rate of recurrence, presumably incurred as a result of disruption of normal bowel flora. There is a need for improved treatment and prevention of this increasingly frequent and debilitating nosocomial infection. Treatments that utilize passive antibodies, immunization, nontoxigenic C. difficile, or other forms of biotherapy may hold the key to improved treatment and prevention of C. difficile disease in the future. In the meantime, it behooves all practitioners to use antimicrobials judiciously in order to prevent as many cases of C. difficile diarrhea as possible.

Abdomen, Acute↗
PubMed2000

SHEA conference on antimicrobial resistance. Society for Healthcare Epidemiology of America.

Antimicrobial resistance is an increasing problem in healthcare institutions and in the community. Public concern about resistance is also increasing. The issue is broad and complex and not readily addressed by government, industry, or professional societies alone. On October 29-30, 1998, 19 representatives of various professional societies and governmental agencies met under the auspices of the Society for Healthcare Epidemiology of America (SHEA) at Brook Lodge Conference Center in Augusta, Michigan. The purpose of the meeting was to discuss the current status of antimicrobial resistance in the United States and Canada, including present society and governmental efforts to address the problem. Representatives exchanged experiences through presentations and discussions on the first day, then on the second day held a brainstorming session to address future needs and priorities in addressing the resistance problem. It was agreed that a national coordinated effort was needed. As part of this national effort, representatives called for the creation of a National Coalition on Antibiotic Resistance (NCAR) to combat antibiotic resistance through education, research, prevention, and advocacy. Priorities for NCAR were focused in four areas: (1) education of the public and professionals; (2) support of basic and applied research; (3) provision of an information resource and clearinghouse; and (4) advocacy initiatives. At the recommendation of the SHEA Board, discussions with the National Foundation for Infectious Diseases for the joint development of NCAR have begun.

Canada↗
PubMed2000

Antimicrobial cycling: lessons learned from the aminoglycoside experience.

Several discrete strategies have been suggested to prevent or reduce microbial resistance to antimicrobials, including optimal use of the agents (also known as good stewardship); control, removal, or restriction of antimicrobials; use of antimicrobials in combination; and rotational or cyclic use of antimicrobials. The latter strategy is attractive because it periodically removes from the institutional environment certain classes or specific agents that could induce or select resistance. Hospitalwide studies of aminoglycoside substitution employed from the late 1970s through the early 1990s, although not originally intended to test cycling or rotation of aminoglycosides, serendipitously provided data that may be useful in designing future studies. In particular, one 10-year study at the Minneapolis Veterans' Affairs Medical Center (MVAMC) rotated amikacin and gentamicin use over cycles of 12 to 51 months' duration. Significantly reduced resistance to gentamicin was found when amikacin was used, but resistance to gentamicin returned with the first gentamicin recycle. This was followed by reintroduction of amikacin a second time with decreased resistance to gentamicin and, finally, a second reintroduction of gentamicin without resistance to it recurring. Thus, some evidence of proof of principal can be garnered, albeit subject to considerable criticism. Critical examination of the design of the aminoglycoside rotation study and the unforeseen pitfalls is provided as a 13-element guidance list for design of future rotational studies. Rotational usage practices are likely to be most appropriate for drugs active against gram-negative bacilli because of the wide choices available for rotation. Future availability of new agents active against resistant gram-positive organisms will present the opportunity to cycle these agents as vancomycin substitutes. Careful monitoring of clinical outcomes and resistance will be required. Multicenter controlled trials that follow carefully designed protocols are most likely to produce statistically significant and clinically meaningful results.

Aminoglycosides↗
PubMed2000

Toxin gene analysis of a variant strain of Clostridium difficile that causes human clinical disease.

A toxin variant strain of Clostridium difficile was isolated from two patients with C. difficile-associated disease (CDAD), one of whom died from extensive pseudomembranous colitis. This strain, identified by restriction endonuclease analysis (REA) as type CF2, was not detected by an immunoassay for C. difficile toxin A. Culture supernatants of CF2 failed to elicit significant enterotoxic activity in the rabbit ileal loop assay but did produce atypical cytopathic effects in cell culture assay. Southern hybridization, PCR amplification, and DNA sequence analyses were performed on the toxin A (tcdA) and toxin B (tcdB) genes of type CF2 isolate 5340. Type CF2 5340 tcdA exhibited a 1,821-bp truncation, due to three deletions in the 3' end of the gene, and a point mutation in the 5' end of the gene, resulting in a premature stop codon at tcdA position 139. Type CF2 5340 tcdB exhibited multiple nucleotide base substitutions in the 5' end of the gene compared to tcdB of the standard toxigenic strain VPI 10463. Type CF2 5340 toxin gene nucleotide sequences and deduced amino acid sequences showed a strong resemblance to those of the previously described variant C. difficile strain 1470, a strain reported to have reduced pathogenicity and no association with clinical illness in humans. REA of strain 1470 identified this strain as a distinct type (CF1) within the same REA group as the closely related type CF2. A review of our clinical-isolate collection identified five additional patients infected with type CF2, three of whom had documented CDAD. PCR amplification of the 3' end of tcdA demonstrated identical 1. 8-kb deletions in all seven type CF2 isolates. REA type CF2 is a toxin variant strain of C. difficile that retains the ability to cause disease in humans but is not detected in clinical immunoassays for toxin A.

Aged↗
PubMed1999

Epidemics of diarrhea caused by a clindamycin-resistant strain of Clostridium difficile in four hospitals.

BACKGROUND: Large outbreaks of diarrhea caused by a newly recognized strain of Clostridium difficile occurred in four hospitals located in different parts of the United States between 1989 and 1992. Since frequent use of clindamycin was associated with the outbreak in one of the hospitals, we examined the resistance genes of the epidemic-strain isolates and studied the role of clindamycin use in these outbreaks. METHODS: Case-control studies were performed at three of the four hospitals to assess the relation of the use of clindamycin to C. difficile-associated diarrhea. All isolates of the epidemic strain and representative isolates of other strains identified during each outbreak were tested for susceptibility to clindamycin. Chromosomal DNA from these representative isolates was also analyzed by dot blot hybridization and amplification with the polymerase chain reaction (PCR) with the use of probes and primers from a previously described determinant of erythromycin resistance - the erythromycin ribosomal methylase B (ermB) gene - found in C. perfringens and C. difficile. RESULTS: In a stratified analysis of the case-control studies with pooling of the results according to the Mantel-Haenszel method, we found that the use of clindamycin was significantly increased among patients with diarrhea due to the epidemic strain of C. difficile, as compared with patients whose diarrhea was due to nonepidemic strains (pooled odds ratio, 4.35; 95 percent confidence interval, 2.02 to 9.38; P<0.001). Exposure to other types of antibiotics or hospitalization in a surgical ward was not significantly associated with the risk of C. difficile-associated diarrhea due to the epidemic strain. All epidemic-strain isolates were highly resistant to clindamycin (minimal inhibitory concentration, >256 microg per milliliter). DNA hybridization and PCR analysis showed that all these isolates had an ermB gene, which encodes a 23S ribosomal RNA methylase that mediates resistance to macrolide, lincosamide, and streptogramin antibiotics. Only 15 percent of the nonepidemic strains were resistant to clindamycin. CONCLUSIONS: A strain of C. difficile that is highly resistant to clindamycin was responsible for large outbreaks of diarrhea in four hospitals in different states. The use of clindamycin is a specific risk factor for diarrhea due to this strain. Resistance to clindamycin further increases the risk of C. difficile-associated diarrhea, an established complication of antimicrobial use.

Anti-Bacterial Agents↗
PubMed1998

Acquisition of Clostridium difficile and Clostridium difficile-associated diarrhea in hospitalized patients receiving tube feeding.

BACKGROUND: Clostridium difficile is the most common infectious cause of nosocomial diarrhea, but its role in diarrhea associated with tube feeding has not been rigorously investigated. OBJECTIVE: To determine the incidence of C. difficile acquisition and C. difficile-associated diarrhea in tube-fed and non-tube-fed patients. DESIGN: Prospective cohort study. SETTING: A university-affiliated Veterans Affairs Medical Center. PATIENTS: 76 consecutive hospitalized, tube-fed patients and 76 hospitalized, non-tube-fed patients. The two cohorts were matched for age, unit location, duration of hospitalization before surveillance, and severity of illness. MEASUREMENTS: Incidence of C. difficile acquisition, incidence of C. difficile-associated diarrhea, and C. difficile restriction endonuclease analysis typing results. RESULTS: More tube-fed patients than non-tube-fed patients acquired C. difficile (15 of 76 patients [20%] compared with 6 of 76 patients [8%]; P=0.03) and developed C. difficile-associated diarrhea (7 of 76 patients [9%] compared with 1 of 76 patients [1%]; P=0.03). The mean proportion (+/-SD) of surveillance days with diarrhea was greater for tube-fed patients after the development of C. difficile-associated diarrhea than for tube-fed patients without this diarrhea (0.68+/-0.4 compared with 0.22+/-0.2 [95% CI for the mean difference, 0.08 to 0.84]). Postpyloric tube feeding (odds ratio, 3.14 [CI, 1.008 to 9.77]) and duration of surveillance (odds ratio, 1.08 [CI, 1.0009 to 1.16]) were risk factors for the acquisition of C. difficile. Nineteen restriction endonuclease analysis types of C. difficile were identified from 20 patients. CONCLUSIONS: Hospitalized, tube-fed patients, especially those receiving postpyloric tube feeding, are at greater risk for the acquisition of C. difficile and the development of C. difficile-associated diarrhea than are hospitalized, non-tube-fed patients. Clinicians should test for C. difficile in tube-fed patients with diarrhea.

Aged↗
PubMed1998

Primary symptomless colonisation by Clostridium difficile and decreased risk of subsequent diarrhoea.

BACKGROUND: Little is known about whether patients who develop Clostridium-difficile-associated diarrhoea (CDAD) are culture-positive or culture-negative before illness. The most important risk factor is antibiotic exposure. We aimed to find out whether patients identified as primary symptom-free C difficile carriers are at higher risk of developing CDAD than patients who are culture-negative. METHOD: We reviewed four longitudinal studies in which 810 patients admitted to hospital were followed up by prospective rectal-swab culture. At least two consecutive weekly cultures were obtained. We calculated the difference in risk of CDAD between colonised and non-colonised patients in each study and combined the results of the four studies in a random-effects model. FINDINGS: Of 618 non-colonised patients (mean follow-up 1.7 weeks [SD 1.3]), 22 (3.6%) developed CDAD, whereas only two (1.0%) of 192 primary symptom-free carriers (1.5 [1.5]) developed CDAD (pooled risk difference -2.3% [95% CI 0.3-4.3], p=0.021). Of patients who received antibiotics, the risk difference was increased: 22 (4.5%) of 491 non-colonised patients compared with two (1.1%) of 176 colonised patients developed CDAD (-3.2% [0.4-6.0], p=0.024). Of the primary symptom-free C difficile carriers, 95 were colonised with toxigenic strains, 76 with non-toxigenic strains, 12 with both toxigenic and non-toxigenic strains (non-concurrently), and nine with strains of undetermined toxigenicity. Nine of the 12 toxogenic strains of C difficile isolates that cause CDAD were also recovered from stools of symptom-free patients. INTERPRETATION: Primary symptomless C difficile colonisation is associated with a decreased risk of CDAD. Although the mechanism is unknown, risk reduction is found in colonisation with non-toxigenic and toxigenic strains.

Adult↗
PubMed1997

Comparison of cycloserine-cefoxitin-fructose agar (CCFA) and taurocholate-CCFA for recovery of Clostridium difficile during surveillance of hospitalized patients.

The effectiveness of cycloserine-cefoxitin-fructose agar (CCFA) and taurocholate-CCFA (TCCFA) in isolating Clostridium difficile from swabs of the rectum or stools from 184 hospitalized patients who were monitored weekly and when they had diarrhea was compared. The number of surveillance time points ranged from two to eight per patient over a period of 4 to 34 days per patient, totalling 621 comparisons of the media. C. difficile was isolated more frequently by TCCFA than CCFA at seven of eight surveillance points, a significant trend (O'Brien test, p = 0.002). This difference reached statistical significance at the second surveillance time point when the prevalence of C. difficile was sufficiently high. At the second surveillance point, C. difficle was isolated only by TCCFA in 7 of 184 comparisons of the media, only by CCFA in none of the comparisons, and by both media in 19 comparisons (p = 0.016). C. difficle was first isolated at an earlier surveillance time point on TCCFA in 11 of 36 patients and on CCFA first only once (p = 0.005). Use of TCCFA media increased the rapidity and sensitivity of culture for C. difficle when doing patient surveillance but did not increase sensitivity when diagnosing patients with diarrhea.

Antibiotics, Antitubercular↗
PubMed1997

Society for Healthcare Epidemiology of America and Infectious Diseases Society of America Joint Committee on the Prevention of Antimicrobial Resistance: guidelines for the prevention of antimicrobial resistance in hospitals.

Antimicrobial resistance results in increased morbidity, mortality, and costs of health care. Prevention of the emergence of resistance and the dissemination of resistant microorganisms will reduce these adverse effects and their attendant costs. Appropriate antimicrobial stewardship that includes optimal selection, dose, and duration of treatment, as well as control of antibiotic use, will prevent or slow the emergence of resistance among microorganisms. A comprehensively applied infection control program will interdict the dissemination of resistant strains.

Anti-Bacterial Agents↗
PubMed1997

Is there a relationship between vancomycin-resistant enterococcal infection and Clostridium difficile infection?

The relationship between vancomycin or metronidazole treatment of Clostridium difficile-associated diarrhea (CDAD) and the occurrence of vancomycin-resistant enterococcus (VRE) infection was investigated by review of 18 case-control studies. Fifteen (83%) of 18 studies found vancomycin use, days of use, or grams used to be significantly associated with VRE infection or colonization. Intravenous vancomycin use was a significant risk in nine of 10 studies, and oral vancomycin use was a significant risk in three of four studies that stratified risk by route of administration. Although statistically associated, oral vancomycin use was so infrequent (25% in the study with the most use) that it is likely to have only a minor influence as a risk for VRE infection or colonization when compared with the much more widespread use of intravenous vancomycin. Metronidazole exposure was found to be a significant risk in four of five studies that specifically assessed this variable, but the indication for metronidazole use was not specified. Risk factors for both VRE infection and CDAD include antimicrobial exposure, number of antimicrobials, days of antimicrobial use, specific agents (third-generation cephalosporins, clindamycin, and imipenem), patient age, length of hospitalization, severity of underlying illness, use of electronic rectal thermometers, enteral feedings, environmental contamination, and contamination of the hands of health care workers.

Anti-Bacterial Agents↗