Isolation of Clostridium difficile from hospitalized patients without antibiotic-associated diarrhea or colitis

Predominant Staphylococcus aureus isolated from antibiotic-associated diarrhea is clinically relevant and produces enterotoxin A and the bicomponent toxin LukE-lukD

Staphylococcus aureus was isolated as the predominant or only isolate from cultures of stools of 60 patients over 2 years in a university hospital, leading to the collection of 114 isolates. Diarrhea was observed in 90% of the patients. Ninety-eight percent of the patients had received antibiotics in the month before the diarrhea. Ninety-two percent of the S. aureus isolates were methicillin resistant. S. aureus was encountered with antibiotic-associated diarrhea among 47 quite elderly patients affected or not affected by a gastrointestinal disease. Among the antimicrobial treatments, cessation of the previous therapy when possible or rapid application of oral vancomycin therapy was the most appropriate. Analysis of total DNA by pulsed-field gel electrophoresis revealed 27 different SmaI pulsotypes distributed in 15 clusters. The pulsotypes never differed for related isolates from a single patient, even if they originated from patients with bacteremia. S. aureus was not isolated as the predominant isolate in cultures of stools of 57 patients who received an antimicrobial treatment for more than 5 days without diarrhea. Occurence of production of both enterotoxin A and the bicomponent leucotoxin LukE-LukD by the S. aureus isolates was significantly different from that by random isolates. The results strongly suggest that when predominant in stool samples, S. aureus should be considered a possible etiologic agent for some cases of antibiotic-associated diarrhea.

Antibiotics for the acute abdomen

Antibiotics are only an adjunct to proper surgical therapy for the treatment of the acute abdomen associated with bacterial secondary peritonitis. Upon presentation, all patients require a preoperative dose of antibiotics for prophylaxis against infection of remaining sterile tissues. Patients found intraoperatively to have an established peritoneal infection benefit from an immediate postoperative course of therapeutic antibiotics. A regimen that adequately covers facultative and aerobic gram-negative bacilli and anaerobic organisms is essential. The duration of therapeutic antibiotics is probably best decided on an individual patient basis. The goal of antibiotics is to reduce the concentration of bacteria invading tissues. The pathogens of bacterial peritonitis are influenced by such factors as the patient's pre-existing chronic diseases, state of acute physiologic debilitation, immunocompetence, recent antibiotic use, recent hospitalization, and neutralization of gastric acidity. Intraoperative peritoneal cultures are most useful in patients suspected of having impaired local host defenses. In these patients, all identified organisms, such as Enterococcus or Candida, may be potential pathogens. The common practice of administering empiric and prolonged courses of broad-spectrum antibiotics in patients who manifest persistent signs of inflammation may be more harmful than beneficial. These patients warrant an exhaustive search for extra-abdominal and intraperitoneal sources of new infection. Otherwise, such use of antibiotics may continue to promote the selection of bacteria that are highly resistant to conventional antibiotics and permit the overgrowth of organisms commonly seen with tertiary peritonitis. The best chance of resolving bacterial peritonitis is through early, aggressive surgical management complemented by short courses of potent antibiotics and appropriate physiologic support. Through these efforts, the clinician tries to help the systemic inflammatory response to benefit the host and not become unregulated, result in MOFS, and produce a high mortality.

Development and clinical evaluation of an amplified flow cytometric fluoroimmunoassay for Clostridium difficile toxin A

A rapid (2 h) amplified flow cytometric fluoroimmunoassay (AFCF) for Clostridium difficile toxin A was developed and compared with the cytotoxin assay (CTA) and culture of the organism from stool specimens from patients with suspected C. difficile-associated gastrointestinal disease (CAD). For this assay polyclonal antitoxin A was attached to 10-microns diameter and monoclonal antitoxin A was attached to fluorescent 0.1 micron-diameter polystyrene microspheres. The microspheres and sample were reacted together as in a conventional double-antibody sandwich assay. However, laser flow cytometric measurement allowed the omission of separation and washing steps by gating on light scattered by the larger microspheres and measuring only the fluorescence associated with these particles. The amount of fluorescence from the attached 0.1 micron microspheres was dependent on the concentration of toxin A in the sample. The AFCF detected purified toxin A at levels of 1 pg/ml and was linear from 1 to 40 pg/ml. The AFCF was compared with the CTA and culture of C. difficile for clinical use by comparing results from 198 stool specimens from patients with suspected CAD. The AFCF was 85.7% sensitive and 95.8% specific relative to the CTA, and 85.2% sensitive and 98.3% specific compared to the culture assay. If the isolation of toxigenic C. difficile or the patients clinical course was considered indicative of CAD, the sensitivities of the AFCF, CTA, and culture assay were 77.4%, 67.7% and 96.8%, respectively. The AFCF demonstrated a specificity of 98.8%, while both CTA and culture had a specificity of 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Pseudomembranous colitis

Pseudomembranous colitis is an inflammatory disease of the colon and rectum characterized by the development of elevated mucosal plaques. It usually is associated with antibiotic therapy and is caused by elaboration of toxin from the anaerobic bacterium, Clostridium difficile. The hallmark of treatment is orally administered vancomycin or metronidazole. The mortality rate is high in patients whose condition is not diagnosed and appropriately treated. Emergency surgery occasionally is needed for complications, including colonic perforation and toxic colitis.

Clostridium difficile: clinical disease and diagnosis

Clostridium difficile is an opportunistic pathogen that causes a spectrum of disease ranging from antibiotic-associated diarrhea to pseudomembranous colitis. Although the disease was first described in 1893, the etiologic agent was not isolated and identified until 1978. Since clinical and pathological features of C. difficile-associated disease are not easily distinguished from those of other gastrointestinal diseases, including ulcerative colitis, chronic inflammatory bowel disease, and Crohn's disease, diagnostic methods have relied on either isolation and identification of the microorganism or direct detection of bacterial antigens or toxins in stool specimens. The current review focuses on the sensitivity, specificity, and practical use of several diagnostic tests, including methods for culture of the etiologic agent, cellular cytotoxicity assays, latex agglutination tests, enzyme immunoassay systems, counterimmunoelectrophoresis, fluorescent-antibody assays, and polymerase chain reactions.

Comparison of three enzyme immunoassays, a cytotoxicity assay, and toxigenic culture for diagnosis of Clostridium difficile-associated diarrhea

Enzyme immunoassays (EIAs) based on monoclonal antibodies for the detection of Clostridium difficile toxins have recently been developed for clinical use. The aim of this study was to compare three commercially available EIAs, two for toxin A (Premier C. difficile Toxin A; Meridian, Osi, Elancourt, France; and Vidas C. difficile Toxin A; bioMérieux, Marcy l'Etoile, France) and one for toxins A and B (Cytoclone A + B EIA; Cambridge Biotech Corp., Codiapharm, Evian, France), with a cytotoxicity assay and toxigenic culture for the diagnosis of C. difficile-associated diarrhea (CDAD). The study was performed with 285 fresh stools from 285 patients with suspected CDAD. In case of disagreement, the tests were repeated on a frozen aliquot of the same stool sample, and the patient's chart was reviewed. CDAD diagnosis was established in 55 cases (incidence, 19.3%). The sensitivities and specificities of the methods were, respectively, 92.7 and 100% for the cytotoxicity assay, 96.4 and 99.1% for toxigenic culture, 75.5 and 97.8% for Cytoclone, 65.4 and 99.6% for Premier, and 65.4 and 100% for Vidas. The results were uninterpretable in 3.2% of cases with Cytoclone, 0.3% with Premier, and 2.5% with Vidas. We conclude that the cytotoxicity assay and toxigenic culture remain the best methods for the diagnosis of CDAD even though they lack standardization and require 48 to 96 h to obtain the result. Despite their rapidity and simplicity, EIAs are not sensitive enough to be relied on as the sole laboratory test.

Laboratory diagnosis of Clostridium difficile-associated gastrointestinal disease: comparison of a monoclonal antibody enzyme immunoassay for toxins A and B with a monoclonal antibody enzyme immunoassay for toxin A only and two cytotoxicity assays

A total of 320 stool specimens obtained from 262 patients suspected of having Clostridium difficile-associated gastrointestinal disease were examined with two cytotoxicity assays (CTAs) and two commercially available enzyme immunoassays (EIAs). The CTAs were an in-house-developed procedure (University of Massachusetts Medical Center [UMMC], Worcester, Mass.) and a commercial test (Bartels CTA; Baxter Healthcare Corp., West Sacramento, Calif.). One EIA was a monoclonal antibody-based assay for C. difficile toxins A and B (Cambridge Biotech Corp. [CBC], Worcester, Mass.). The other EIA employed monoclonal antibodies directed against only toxin A (Meridian Diagnostics, Cincinnati, Ohio). True-positive and true-negative results were defined on the basis of the results of the four assays, clinical assessments of patients, and the results of other laboratory tests. The sensitivities of the four assays were as follows: Bartels CTA, 100%; UMMC CTA, 97.2%; CBC EIA, 84.5%; and Meridian EIA, 69.0%. The Bartels CTA demonstrated a specificity of 99.2%. The other three assays had a specificity of 100%.

The clinical significance of antibiotic-associated pseudomembranous colitis in the 1990s

Antibiotic-associated pseudomembranous colitis is an uncommon but potentially serious adverse reaction, resulting in acute diarrhoea and characterised by colonic pseudomembranes. A direct relationship between the disease, recent antibiotic therapy and proliferation of Clostridium difficile in the colonic lumen was established in the late 1970s. It is thought that antibiotic therapy may alter the enteric flora, enabling C. difficile to proliferate and produce toxins with cytopathic (toxin B or cytotoxin) and hypersecretory (toxin A or enterotoxin) effects on the mucosa. Apart from clindamycin, the first antibiotic recognised to be clearly associated with pseudomembranous colitis, the antimicrobial agents most commonly responsible are cephalosporins and ampicillin (or amoxicillin). However, virtually all antibiotics except parenterally administered aminoglycosides can cause the disease. Vancomycin and metronidazole, 2 drugs used to treat antibiotic-associated pseudomembranous colitis, have also been reported to be responsible for the complication when used parenterally. Pseudomembranous colitis may develop after perioperative prophylactic antibiotic therapy with cephalosporins. Antibiotic-associated pseudomembranous colitis is most frequent in elderly and debilitated patients and in intensive care units. Nosocomial acquisition of C. difficile has been documented. Therefore it has been recommended that enteric isolation precautions should be taken with patients with this disease. The clinical symptoms include watery diarrhoea, abdominal cramping, and frequently fever, leucocytosis and hypoalbuminaemia. Toxic megacolon and acute peritonitis secondary to perforation of the colon are the most serious complications. The pseudomembranes are usually seen during endoscopic procedures, sigmoidoscopy or, if possible, colonoscopy; the most useful microbiological tests for confirmation of the diagnosis include cycloserine cefoxitin fructose agar (CCFA) stool cultures and stool toxin assays on tissues or by immunological techniques. However, cultures and toxin tests may be positive in patients without pseudomembranous colitis or C. difficile-associated diarrhoea. Mild cases may respond to discontinuation of the drug responsible, but therapy with an anticlostridial antibiotic is often necessary: a 10-day course of oral vancomycin, metronidazole or bacitracin should be given. Relapses are seen in 5 to 50% of patients treated. Antibiotic treatment should avoid sporulation leading to other relapses. 'Biotherapy' (lactobacilli, Saccharomyces) has also been proposed.

Comparison of a dot immunobinding assay, latex agglutination, and cytotoxin assay for laboratory diagnosis of Clostridium difficile-associated diarrhea

C. diff-CUBE, a dot immunobinding assay (DIA) (Difco Laboratories, Ann Arbor, Mich.) for detection of Clostridium difficile toxin A in stool specimens, was compared with latex agglutination (LA) (Marion Laboratories, Kansas City, Mo.) and cytotoxin assay (CTA) for the laboratory diagnosis of C. difficile-associated diarrhea. A total of 200 stool specimens collected from 169 patients with suspected C. difficile diarrhea were tested. Of the 198 specimens evaluated by all three methods, 36 (18%) from 36 patients were positive by one or more of the tests. Twenty-five, 26, and 23 specimens were positive by CTA, DIA, and LA, respectively; 14 were positive by all three methods. Eight specimens yielded nonspecific LA test results; all eight were negative by CTA, and one was positive by DIA. DIA results agreed with CTA results in 183 (92%) cases and with LA results in 175 (88%) cases. CTA and LA results agreed in 179 (90%) cases. Freezing of the specimen did not appear to adversely affect either the DIA or LA test. These preliminary results suggest that C. diff-CUBE may be useful as a rapid screen for the diagnosis of C. difficile-associated diarrhea. However, for optimum laboratory diagnosis, further testing of all stools that are negative by DIA is warranted.

Evaluation of a latex agglutination test for Clostridium difficile in two nursing home outbreaks

The Culturette Brand Clostridium difficile test (CDT; Marion Laboratories, Inc., Kansas City, Mo.) is a latex agglutination test for C. difficile. The recent controversy involving the identity of antigens detected by CDT has made decisions on its use difficult. We compared the test results with those of selective culture and stool cytotoxin assays in investigations of two nursing home outbreaks of C. difficile-associated disease in order to formulate usage recommendations. Selective culture for C. difficile identified 27 (19%) of 142 subjects as carriers. CDT and the stool cytotoxin assay identified only 52 and 48% of these carriers, respectively. Compared with the stool cytotoxin assay, CDT had a high sensitivity (92%) and specificity (89%) for the detection of C. difficile disease, but the positive predictive value of the test was only 17% when the prevalence of disease was 2%. We conclude that the CDT should not be used to identify carriers but that it is a sufficiently sensitive and specific screening test for diagnosing C. difficile disease. However, since the positive predictive value of the CDT is low when the prevalence of disease is low, positive test results should be confirmed by the stool cytotoxin assay.

Nosocomial diarrhoeas in a surgical division hyperendemic for Clostridium difficile: epidemiologic aspects emerging from an analysis of clinical records

Having previously shown that Clostridium difficile was responsible for an intense and protracted endemic of nosocomial diarrhoeas in the surgical division of a Tuscan hospital, we started a retrospective analysis on all records from the affected division, to cover a period of 15 months. A statistical description is given of a large series of nosocomial diarrhoeas, as well as direct estimates of their incidence rates in selected high risk subgroups. The situation described is epidemiologically unique, and its study tells how an endemic may reach a steady state of high nosocomial morbidity.

Variations in the anaerobic faecal flora of ten healthy human volunteers with special reference to the Bacteroides fragilis-group and Clostridium difficile

Ninety nine stool specimens of ten healthy human volunteers were collected over a one year period, and processed anaerobically. The individual variations in intestinal colonization with bacteria of the Bacteroides fragilis-group were detected, using the Bacteroides Bile Esculin medium and an identification scheme for bile-resistant Bacteroides species. Clostridium difficile agar supplemented with cycloserine/cefoxtin was used to detect the incidence of C. difficile in this group. The species of the B. fragilis-group most often detected were: B. vulgatus (in 31 samples from ten persons), B. uniformis (22/9), B. fragilis (19/7). C. difficile was never detected in this group. The mean total anaerobic cultural counts (log) of the ten volunteers varied between 9.94 and 10.91. This shows that interindividual variations in anaerobic cultural counts of about one log are common. In spite of these moderate interindividual variations, intraindividual variations in time of up to three log were detected. The mean Bacteroides cultural counts showed a variation between 8.83 and 10.24. The mean DMCCs of the ten volunteers were between 10.22 and 10.73. We conclude that at least a three to four log difference from the control samples will be required to establish a significant change in anaerobic cultural count due to antibiotic treatment.

Clostridium difficile-associated diarrhea follows perioperative prophylaxis with cefoxitin

Clostridium difficile-associated diarrhea during prolonged therapy of obstetric and gynecologic infections is known to occur with use of all classes of antibiotics except vancomycin and the aminoglycosides. We present 11 cases of C. difficile-associated diarrhea which followed a short course of perioperative prophylaxis with cefoxitin during a 1-year period. Nine of the cases of C. difficile-associated diarrhea were among 162 women who received cefoxitin perioperative prophylaxis for cesarean section or hysterectomy, but none occurred in 85 women who received one of four other antibiotics for perioperative prophylaxis (p = 0.024, Fisher's exact test). The two other occurrences of C. difficile-associated diarrhea following perioperative prophylaxis with cefoxitin were in women who underwent exploratory laparotomy. We conclude that C. difficile-associated diarrhea is related to perioperative prophylaxis with cefoxitin.

Prospective randomised trial of metronidazole versus vancomycin for Clostridium-difficile-associated diarrhoea and colitis

101 patients with Clostridium-difficile-associated diarrhoea or colitis were prospectively randomised to 10-day oral courses of metronidazole, 250 mg four times a day, or vancomycin, 500 mg four times a day. 7 did not complete the protocol and were dropped from analysis. Pseudomembranous colitis (PMC) was diagnosed after endoscopy in 33 patients. Of the remaining patients without PMC, 38 had both C difficile culture and cytotoxin and 23 had only culture evidence of C difficile. 52 evaluable patients received vancomycin and 42 received metronidazole. There were two treatment failures with metronidazole and none with vancomycin (p = 0.20); and two relapses with metronidazole versus six with vancomycin (p = 0.17). Treatment in 1 patient in each group was discontinued because of drug intolerance. Response and relapse rates of the 33 patients with PMC were no different from those of the remaining patients. Pharmacy cost for the dosage used was $387.48 to $520.00 for vancomycin and $11.84 for metronidazole. Metronidazole and vancomycin have equivalent efficacy and relapse rates and are tolerated to a similar extent by patients with C-difficile-related diarrhoea and colitis, but metronidazole is considerably more economical.