Selective and differential medium for isolation of Clostridium difficile

Intestinal colonization of infant hamsters with Clostridium difficile

Infant hamsters of different ages were examined for their susceptibility to enteric Clostridium difficile colonization. Intragastric administration of C. difficile to infant hamsters resulted in multiplication of the organism in the intestinal tracts of animals 4 to 12 days old; hamsters younger or older were resistant to C. difficile intestinal colonization. Toxicity to the colonized animals could not be demonstrated despite cytotoxin titers in some infant hamsters comparable to titers found in the intestinal tracts of adult hamsters with C. difficile-associated intestinal disease. When introduced into 4-day-old hamsters, C. difficile colonized the intestinal tract and remained at high levels until the animals were 13 days old, at which time the presence of intestinal C. difficile could no longer be demonstrated. The number of C. difficile required to colonize the intestinal tracts of 50% of 7-day-old hamsters was 18 viable cells. On the other hand, 10(8) viable cells of C. difficile failed to colonize the intestinal tracts of healthy, non-antibiotic-treated adult hamsters.

Efficiency of various bile salt preparations for stimulation of Clostridium difficile spore germination

Taurocholate, desoxycholate, and cholate stimulated germination of Clostridium difficile spores in broth medium and enhanced recovery of C. difficile spores on a selective agar medium. Desoxycholate and some crude taurocholate preparations also inhibited multiplication of vegetative cells. At a concentration of 1.2 X 10(-2) M, sodium cholate inhibited multiplication of vegetative cells, but at concentrations of 1.2 X 10(-3) to 2.4 X 10(-3) M, it stimulated germination without inhibiting cell multiplication. Thus, pure sodium taurocholate and sodium cholate may effectively be incorporated in cefoxitin-cycloserine-fructose agar, whereas some crude preparations of sodium taurocholate decrease recovery on this medium.

Anaerobes in genitourinary infections in men

Urethral and sub-preputial swabs from 150 men were examined. There was a strong association between the isolation of anaerobic bacteria, particularly Bacteroides spp, and a clinical diagnosis of balanoposthitis, non-specific urethritis (NSU), or both. Aerobic bacteria formed the predominant flora in 28 healthy controls whereas anaerobes were predominant in specimens from 79 patients with balanoposthitis, from 24 with NSU, and from 19 with both. Bacteroides spp were the commonest isolates in all patient groups; B asaccharolyticus, B melaninogenicus ss intermedius, B ureolyticus, and B bivius were the most common species. The results obtained with the two swabs were identical except that Gardnerella vaginalis was isolated from the urethral swab only in five patients.

Isolation and identification of anaerobic organisms from the male and female urogenital tracts

Since Bacteroides spp may play an important role together with Gardnerella vaginalis in the pathogenesis of non-specific vaginitis and balanoposthitis, anaerobic organisms were isolated and identified from 34 female and 20 male patients attending a department of genitourinary medicine, and the results compared with the clinical findings and the presence of other routinely isolated pathogens. Twenty-three different organisms were recovered from 13 of the 20 men; of these organisms, 20 were of the Bacteroides spp. Most isolates were of the B melaninogenicus/oralis group, which forms part of the commensal vaginal flora in women. A definite association between the presence of anaerobes and other pathogens needs to be firmly established, as this obviously causes important complications in treating these conditions.

Influence of age, sex, and diet on asymptomatic colonization of infants with Clostridium difficile

A total of 40% of 107 stool samples from infants 1 to 52 weeks of age were found to contain Clostridium difficile antigens, detected by counterimmunoelectrophoresis. Within the group tested, there was no detectable variation by age or sex. Infants fed formula were nearly four times more likely to carry C. difficile than were those exclusively breast fed (62 versus 16%), whereas breast-fed infants also receiving formula or solids had an intermediate rate of colonization (35%). The distributions were similar when a subgroup with the highest levels of antigen was assessed separately. These data will be useful in considering potential pathogenic activities of C. difficile colonization in infancy.

Evaluation of the usefulness of counterimmunoelectrophoresis for diagnosis of Clostridium difficile-associated colitis in clinical specimens

Results of counterimmunoelectrophoresis (CIE) were compared with those of isolation of Clostridium difficile and assay for cytotoxicity in HeLa cells. On the basis of 471 stool specimens, CIE exhibited a sensitivity of 38% and a specificity of 88% as compared with the cytotoxin assay. The predictive value of a reactive CIE results is low (17%), whereas the predictive value of a nonreactive CIE result is significant (96%) and therefore warrants its use as a screening test. In addition, stool filtrates may nonspecifically precipitate with the C. difficile antitoxin in the CIE test. Such nonspecific reactions may be identified by simultaneous electrophoresis against nonimmune serum.

A selective broth for Clostridium difficile

A selective broth for the isolation of Clostridium difficile from stool specimens is described. The broth contains gentamicin, cycloserine and cefoxitin (GCC broth) and gives rapid presumptive evidence of the presence of C. difficile using gas-liquid chromatography. The broth may also be used for the detection of cytotoxin. Final recovery of C. difficile was significantly improved with an increase in isolation rate of 20% in patients in whom fecal cytotoxin could be detected and 125% in patients where fecal cytotoxin could not be detected. Until the pathogenesis of C. difficile-associated diseases is more clearly defined we would stress the importance of isolating the organism, and we advocate the use of a selective broth such as GCC to improve the isolation rate.

Relapse of antibiotic associated colitis: endogenous persistence of Clostridium difficile during vancomycin therapy

This study reports 24 patients with antibiotic associated colitis due to Clostridium difficile. Fifteen patients were treated with vancomycin due to the severity of the colitis and in eight of these a clinical relapse of the colitis occurred after vancomycin therapy was stopped. Bacteriological investigations of these patients indicated that C difficile was able to persist in stool samples during vancomycin therapy in the absence of detectable cytotoxin. This was in contrast with the seven patients successfully treated with vancomycin without relapse, and those not treated with vancomycin where both stool cultures and cytotoxin assays became negative. These results suggest that patients being treated with vancomycin for antibiotic associated colitis due to C difficile should have stool cultures done during and after treatment. Persistence of the organism in the absence of detectable cytotoxin may identify those patients who relapse and lead to either recommencement of vancomycin or alternative therapeutic approaches.

Role of Clostridium difficile and Campylobacter jejuni in relapses of inflammatory bowel disease

Findings from recent studies on the role of Clostridium difficile and Campylobacter jejuni in exacerbations of inflammatory bowel disease are in conflict. We examined stool specimens from 32 patients who had inflammatory bowel disease in relapse for the presence of C difficile and C difficile cytotoxin. In the last 19 cases stool specimens were also cultured for C jejuni. C difficile was identified in one patient who was receiving antimicrobial therapy. In no patient was C difficile cytotoxin detected. All cultures for C jejuni were negative. Routine screening of stool specimens for C difficile cytotoxin and C jejuni was not clinically useful in our patients during exacerbation of their inflammatory bowel disease.

Outbreaks of diarrhea associated with Clostridium difficile and its toxin in day-care centers: evidence of person-to-person spread

Clostridium difficile was associated with five outbreaks of diarrhea occurring in three day-care centers caring for children less than 2 years of age during a three and one-half-month period; two centers had one outbreak of diarrhea, and one had three outbreaks. The frequency of isolation of C. difficile and its toxin was determined in stool specimens from 65 children attending the three day-care centers. Twelve of 21 (57%) children who had diarrhea excreted C. difficile and its toxin, whereas only four of 44 (9%) children who did not experience diarrhea yielded the organism and the toxin. Five of the 12 symptomatic children with C. difficile and its toxin had received prior antimicrobial therapy for upper respiratory tract infections. An eight-month prospective study was then carried out in one room of the center where the three outbreaks had occurred. Initially, one child had culture-positive stools for C. difficile. During the first 13-week study period six additional children of the 12 (50%) in the room under study became colonized with C. difficile. Six of the seven children who excreted C. difficile and its toxin experienced diarrhea with C. difficile toxin-positive stools by the end of the 13 weeks. Environmental contamination increased as more children became colonized and developed diarrhea. Electrophoretic evaluation of environmental and stool isolates obtained during one outbreak of diarrhea showed that the isolates had an identical protein pattern. Findings of this study indicate the importance of searching for C. difficile in children in day-care centers who develop diarrhea.

Diarrhoea associated with Clostridium difficile in a hospital population

The incidence of disease associated with Clostridium difficile was investigated in a general hospital population over a period of six months. In 26 (14.5%) of 179 patients studied, C. difficile was either isolated or faecal cytotoxin was detected. The incidence of other enteropathogenic bacteria, except Aeromonas hydrophila, was low. Faecal cytotoxin was not detected in nine patients (35%), and non-cytotoxigenic strains of C. difficile were isolated from these patients. In seven patients, a selective broth was required to isolate C. difficile, suggesting their presence in low numbers. Although some C. difficile diarrhoeal disease which was not associated with antibiotic therapy was recorded, prior exposure to antibiotic agents still appears to be the major predisposing factor in this population. Faecal cytotoxin detection, sigmoidoscopy, and rectal biopsy were not reliable investigations for disease associated with C. difficile; hence, we advocate increased emphasis on isolation of the causative organism. Routine culturing for C. difficile in a hospital population appears to be warranted.

Isolation of Clostridium difficile from patients and the environment of hospital wards

Rectal swabs from 122 patients and 497 environmental swabs from several wards were examined for the presence of Clostridium difficile in order to assess the role of the environment in the spread of this organism. Clostridium difficile was isolated from 6/27 (22.2%) oncology patients and from 8/163 (4.9%) environmental specimens obtained from the oncology unit. Items found positive for C difficile were those subjected to faecal contamination such as commode chairs, bed pans, dust pans, discard bins, the sluice and a disposable bed pan machine. Fourteen of 51 (27.4%) asymptomatic neonates yielded mostly toxigenic C difficile in their stools during their first week of life. Five of 156 (3.2%) specimens taken from inanimate objects in the environment of the neonatal units were positive for C difficile. The organism was also isolated from the hands of a nurse. Similar antibiogram patterns were demonstrated in the strains obtained from the patients and their environment indicating the possible occurrence of cross infection. These results indicate that environmental contamination is important in the spread of C difficile in hospitalised patients and the implementation of isolation procedures may limit that spread.

Differentiation of Clostridium difficile toxin from Clostridium botulinum toxin by the mouse lethality test

The mouse lethality test is the most sensitive method for confirming the diagnosis of infant botulism. Both Clostridium difficile and Clostridium botulinum produce heat-labile toxins which are lethal for mice and can be found in the feces of infants. These two toxins can be distinguished from one another in this assay when both are present in the same fecal specimen because they appear to be immunologically distinct toxins.

A new selective medium for the culture of clostridia from human faeces

A new selective medium, sulphite-polymixin-milk (SPM) agar, for the isolation of clostridia from faeces is described. This medium contains whole cow's milk, which favours the growth of clostridia over that of Bacteroides and Bifidobacterium spp., and only small amounts of colistin (10 micrograms/ml) for suppressing growth of coliforms. The alkaline end-products of clostridia give rise to yellow colonies on a red background which are easy to distinguish from the red colonies of other not completely inhibited bacteria. The medium is suitable for isolation of many clostridia species. Comparisons were made between SPM and several other media for recovery of clostridia. The detection limit on SPM agar was more than 10(3) below that on Reinforced Clostridia Agar (Oxoid CM101).

Reactive arthritis associated with Clostridium difficile

A case of reactive arthritis in a patient with a previously documented history of Reiter's syndrome is described. The precipitating agent appears to have been Clostridium difficile. High levels of toxin were demonstrable in the faeces and neutralising antitoxin was detected in the patient's serum but not synovial fluid. Resolution of the polyarthropathy was slow despite successful eradication of the C. difficile with a course of vancomycin.

Impact of cefoperazone therapy on fecal flora

To evaluate the effects of parenteral cefoperazone therapy upon human fecal flora, fecal specimens obtained from four patients before and during therapy (as well as after therapy for one patient) were cultured quantitatively for facultative, aerobic, and anaerobic bacteria and for fungi. Cefoperazone therapy was associated with major changes in fecal flora. There was suppression to undetectable levels or an appreciable reduction in all anaerobic bacteria as well as suppression of all initially detected Enterobacteriaceae. During therapy, there was acquisition or an increase in counts of Candida spp., so that these became the most numerous fecal microorganisms in all patients. In addition, Pseudomonas spp. and coagulase-negative Staphylococcus sp. were acquired by three patients. These marked alterations in flora have potentially important consequences.

Clostridium difficile and cytotoxin in feces of patients with antimicrobial agent-associated pseudomembranous colitis

Thirty patients with antimicrobial agent-associated pseudomembranous colitis (PMC) were studied for the presence of Clostridium difficile and its cytotoxin in feces. Either colonoscopy or barium enema radiography was required in three patients for the diagnosis of PMC because of nondiagnostic findings at sigmoidoscopy. Both the organism and cytotoxin were detected in 27 of the 30 patients; Staphylococcus aureus was excluded as the cause of PMC in two of the remaining patients. Eighteen of 19 patients with C. difficile-induced PMC who were treated with oral vancomycin had a salutary response; seven patients, however, had a relapse of colitis following the discontinuation of vancomycin. In general, relapses of colitis responded to retreatment with vancomycin. The implication of C. difficile as a cause of diarrhea is best achieved by the demonstration of colonic mucosal plaques or of a pseudomembrane. The value of fecal culture for C. difficile and cytotoxin assay is limited by the existence of asymptomatic carriers.

Contamination and crossinfection with Clostridium difficile in an intensive care unit

An outbreak of pseudomembranous colitis in an intensive care unit is described. This resulted in environmental contamination by Clostridium difficile. The outbreak could be traced to one patient who received several antibiotics over the preceding three months. A search was conducted for asymptomatic carriers among patient and staff but none were found. Aquisition of C. difficile from inanimate environmental sources was the most probable means of transmission of the organism. Its persistence in the hospital environment for several weeks, most likely as spores, suggests that patients who develop pseudomembranous colitis should be isolated, especially in areas of high antibiotic usage.

Clostridium difficile and its cytotoxin in feces of patients with antimicrobial agent-associated diarrhea and miscellaneous conditions

Fecal specimens from 223 subjects were evaluated for the presence of Clostridium difficile by use of a selective medium developed in our laboratory and for the presence of C. difficile cytotoxin. C. difficile and cytotoxin were detected in 89 and 83%, respectively, of patients with antimicrobial agent-associated pseudomembranous colitis (PMC). In patients in whom PMC was not documented, C. difficile and cytotoxin were present in only 37 and 21%, respectively. C. difficile and cytotoxin were also recovered from the feces of 6 and 3, respectively, of 13 antimicrobial recipients who did not have diarrhea. Although C. difficile appears to be a major cause of PMC, it is not responsible for at least some two-thirds of cases of antimicrobial agent-associated diarrhea in which PMC is not documented. Neither the recovery of C. difficile nor the detection of its cytotoxin should be considered diagnostic for C. difficile-induced disease.

Clostridium difficile and cytotoxin in routine faecal specimens

Over a five-month period 1239 unselected, routine faecal specimens from 856 patients were examined for Clostridium difficile. One hundred specimens representing 69 patients were culture-positive. Toxin was detected in the stool of ten. During the study period, there were 41 Salmonella, 12 Campylobacter and 9 Shigella infections. C difficile was isolated together with Salmonella from 12 patients. No patient required specific treatment for C difficile infection. The significance of these findings is discussed.

In vitro susceptibility of Clostridium difficile isolates to cefotaxime, moxalactam, and cefoperazone

The in vitro susceptibility of 20 isolates of Clostridium difficile to cefotaxime, moxalactam, and cefoperazone was determined by a standard agar dilution method. The median minimal inhibitory concentrations were 64, 32, and 32 mug/ml for cefotaxime, moxalactam, and cefoperazone, respectively.

Effects of the two toxins of Clostridium difficile in antibiotic-associated cecitis in hamsters

Hamsters were vaccinated with toxoids containing toxin A, toxin B, both toxins, or a preparation containing neither toxin of Clostridium difficile, the causative agent of antibiotic-associated cecitis in hamsters and pseudomembranous colitis in humans. To determine whether these vaccines would reduce the severity of antibiotic-associated cecitis, the hamsters were injected subcutaneously with clindamycin. Nearly all of the hamsters protected against neither toxin or only one toxin died. These animals developed enlarged hemorrhagic ceca and diarrhea, although the ceca from the animals immunized against toxin B were less hemorrhagic. The hamsters immunized against both toxins survived clindamycin treatment and had ceca of normal size and appearance. Concentrations of both toxins were lower in the ceca of the latter animals than in the unprotected animals. To determine the effects of either toxin alone on the animals, nonimmunized hamsters were injected with either purified toxin A, which produced enlarged ceca with moderate hemorrhaging, or partially purified toxin B, which produced hemorrhagic ceca of normal size. All of the hamsters injected with either toxin at concentrations found in the ceca after clindamycin treatment died. These results suggest that toxin A causes the water influx, that both toxins cause hemorrhaging to different extents in the ceca of hamsters with antibiotic-associated cecitis and that either toxin alone can cause death. These studies may help explain the etiology of pseudomembranous colitis in humans.

Clostridium difficile toxin in faecal specimens of healthy children and children with diarrhoea

Presence of cytopathogenic effect (CPE) that could be inhibited by an antitoxin to Clostridium sordelli, known to cross-react with Clostridium difficile toxin, was sought in faecal specimens from 101 infants. Of the children, 45 were healthy, while 56 had been hospitalized because of diarrhoea. CPE was found in 12 of the healthy infants and in 5 of those hospitalized. Faecal specimens of these 5 gave a CPE at titres of 10(3-4), whereas in the 12 healthy infants the titres were 10(1-2). Studies on consecutive samples showed that the CPE could persist for between 7-11 weeks up to 9 months and more. Of the 45 healthy infants, 11 harboured C. difficile compared with 6 of the 56 with diarrhoea. In both groups, 3 CPE-positive infants were culture-negative for C. difficile. Four of those hospitalized had recently been given antibiotics; all were negative in both culture and CPE tests. The present study demonstrates that care should be exercised when interpreting the results of cultures for C. difficile and tests for CPE made on faecal specimens in order to establish a diagnosis of antibiotic-associated enterocolitis in infants and children.

The prevalence of Clostridium difficile and toxin in a nursery population: a comparison between patients with necrotizing enterocolitis and an asymptomatic group

During a period when certain neonates in our nursery developed necrotizing enterocolitis, we studied stool specimens from a population of symptomatic and asymptomatic patients for the presence of Clostridium difficile and its toxin. The presence of the organism among nursery personnel and in the nursery environment was also evaluated. Results showed that five symptomatic neonates and 17 asymptomatic neonates in a population of 37 patients studied in our neonatal intensive care and intermediate care nurseries had positive stool cultures for C. difficile. Toxin was detected in stool from four of five symptomatic patients and was present at dilutions of greater than 1/125 in stool from six asymptomatic patients who were culture positive for C difficile. The organism was not found in stool samples from any nursery personnel but was recovered from the hand culture of a nursery worker and from the inanimate environment. Although our findings support the notion of nosocomial spread of C difficile, we were unable to clearly implicate the organism as the cause of necrotizing enterocolitis in our nursery.

Rapid identification of Clostridium difficile by toxin detection

Rapid identification of Clostridium difficile in a stool specimen could be accomplished within 24 h by detection of toxin elaborated in an agar or broth culture containing cycloserine and cefoxitin. Broth culture seemed to give a more rapid and sensitive result than the agar plate culture. For cultivation of C. difficile in stool, we recommend the use of chopped meat broth and blood agar plate, the former for toxin detection in 1 to 2 days and the latter for colonial morphology and isolation of a pure culture.

Clostridia isolated from the feces of infants during the first year of life

Clostridia isolated from the feces of ten healthy infants during the first year of life were identified. All infants excreted clostridia during the first week of life; the most common species were Clostridium butyricum, C. paraputrificum, and C. difficile. In the formula-fed infants colonization occurred consistently throughout the year, whereas in some breast-fed infants it was inhibited until weaning. The species isolated most frequently throughout the year were C. paraputrificum, C. butyricum, C. ramosum, C. sartagoformum, and C. perfringens. Of the species often found in infants, C. butyricum, C. difficile, and C. sartagoformum occur rarely in adults, reflecting differences in the environmental conditions in the gut of the two age groups. The mechanism by which environmental conditions select species of clostridia is unknown but may be important to our understanding of a variety of clostridial intestinal infections. It was demonstrated that species of clostridia which have been implicated in the etiology of neonatal necrotizing enterocolitis form part of the normal infant gastrointestinal microflora.

Colonization of the large bowel by Clostridium difficile in healthy infants: quantitative study

Colonization of the large bowel of healthy infants by Clostridium difficile was studied. Feces were collected from five breast-fed aand five formula-fed infants throughout the first year of life, and levels of C. difficile were quantitated. Three breast-fed and five formula-fed infants were colonized for periods of between 8 and 42 weeks, and another infant harbored the organism only during week 1. Colonization of breast-fed infants commenced before or during weaning, with levels reaching 10(3) to 10(5) organisms per g of wet feces. Colonization of formula-fed infants commenced before solid foods were given, with levels of 10(3) to 10(7) organisms per g of wet feces. Isolates from eight of the babies were shown to produce cytotoxin in vitro. Single fecal specimens from 60 more children aged up to 4 years were also examined, and it was found that the carriage rate of C. difficile fell sharply after 1 year of age, although in the second year it was still higher than in adults. These findings are discussed in relation to the microbial ecology of the large bowel and the paradox that levels of C. difficile in the large bowel of healthy infants are similar to those causing pseudomembranous colitis in patients.

Use of sodium taurocholate to enhance spore recovery on a medium selective for Clostridium difficile

Isolation of Clostridium difficile from fecal specimens has been facilitated by the development of a selective and differential medium, cefoxitin-cycloserinefructose agar (CCFA). We substituted 0.1% sodium taurocholate for the 2.5% egg yolk in CCFA and compared the growth of 15 isolates of C. difficile on the resulting medium with growth on conventional CCFA. The taurocholate-containing medium (TCCFA) quantitatively recovered vegetative forms of C. difficile in the same numbers as CCFA medium. Recovery of spores was a mean 1.7 log(10) higher on TCCFA than on CCFA. Thirty-six of 60 patient stool specimens growing C. difficile gave a heavier growth on TCCFA than on CCFA, and 9 failed to yield C. difficile on CCFA. TCCFA detected spores of 75 colony-forming units per ml from artificially inoculated fecal specimens when conventional stool culturing techniques were used. Fluorescence of colonies of C. difficile was more intense on TCCFA than on CCFA. TCCFA was simpler to prepare and, overall, was more sensitive than CCFA.

Problems associated with counterimmunoelectrophoresis assays for detecting Clostridium difficile toxin

The antitoxins currently used for the detection of Clostridium difficile by counterimmunoelectrophoresis react with other C. difficile antigens in addition to the toxins produced by the bacterium.

Intestinal occurrence of Campylobacter fetus subspecies jejuni and Clostridium difficile in children in Sweden

Stool samples were cultured from 356 children in different states of health and in different age groups between birth and six years of age in order to investigate the occurrence of Campylobacter jejuni and Clostridium difficile. Campylobacter jejuni was isolated from two of 56 children with diarrhoea but was not isolated from any of 300 healthy children or children recently treated with antibiotics. Campylobacter jejuni does not seem to be a common cause of diarrhoea in children in Sweden and is definitely not a member of the normal fecal flora. Clostridium difficile was isolated from 17 of 100 healthy children one week to one year old, and from one of 100 perinatal children. About the same isolation frequency was found in children with diarrhoea and in children recently treated with antibiotics. A total of 34 isolates of Clostridium difficile were obtained, 29 of which were from children less than one year old. The isolation of Clostridium difficile in stools of children should in most cases be considered a normal finding.

Clostridium difficile in association with sporadic diarrhoea

A total of 154 patients admitted to an infectious diseases unit were included in a year's prospective survey of sporadic diarrhoeal disease. Stools from 19 of them yielded Clostridium difficile, generally on more than one occasion. Twelve of these patients were assessed as having a severe or moderately severe gastrointestinal illness: Cl difficile was the only pathogen isolated from 10 of them, and two had an associated salmonella infection. Seven had had a recent course of antibiotics, but five had not taken antibiotics. Faeces from seven patients with moderate or mild gastrointestinal illness yielded Cl difficile, and two of these patients also had an associated salmonella infection. Two patients in this group had no antibiotic history. From these findings, the occurrence of C difficile in faeces could not be described as antibiotic-associated. Faecal Cl difficile cytotoxin was detected in only six patients, and generally at low levels. In such patients a more relevant pathogenic index might take account of the numbers of Cl difficile present and of their toxigenic potential.

Bacillus pumilus in the induction of clindamycin-associated enterocolitis in guinea pigs

Antibiotic-associated enterocolitis was induced in guinea pigs by the intraperitoneal injection of clindamycin. The colonic and cecal mucosa and feces of acutely ill animals were cultured under aerobic and anaerobic conditions on 5% sheep blood agar plates and on a selective and differential medium for Clostridium difficile. All morphologically distinct colony types were isolated in pure culture and identified. A sterile cell-free filtrate of each isolate was tested for ability to induce morphological changes in cultured monolayers of mouse adrenal cells. The filtrate of a predominant isolate, Bacillus pumilus, induced an alteration of cellular morphology; the sterile filtrate of other isolates were unreactive. Toxin contained in cell-free filtrates of B. pumilus caused a syndrome identical to clindamycin-associated enterocolitis when injected intracecally into guinea pigs. The toxin had a molecular weight of 6,500 daltons as determined by molecular sieve chromatography and was inactivated with pronase, lipase, and trypsin. The minimal inhibitory concentrations of clindamycin and vancomycin for B. pumilus were 50 micrograms/ml and less than or equal to 0.4 micrograms/ml, respectively.

Suppression of Clostridium difficile by normal hamster cecal flora and prevention of antibiotic-associated cecitis

Administration of normal cecal homogenates decreased numbers of viable Clostridium difficile and prevented cecitis in antibiotic-challenged hamsters. Cecal anaerobes appeared to suppress C. difficile.

Treatment of Clostridium difficile colitis and diarrhea with vancomycin

Toxigenic Clostridium difficle is the major cause of antibiotic-associated colitis and is susceptible to vancomycin at fecal concentrations achieved with oral therapy. The effect of oral vancomycin was studied in 16 patients with C. difficile-related diarrhea or colitis, 12 of whom had colitis documented by endoscopy, biopsy, and/or barium enema. Four patients had antibiotic-associated diarrhea and possibly antibiotic-associated colitis, because sigmoidoscopy either showed normal results (two patients) or was not performed (two patients). Nineteen episodes of diarrhea were treated with oral vancomycin in two dosage regimens for three to 14 days. Twelve patients received 2 g daily, and four patients initially received 1 g or less per day. Within 48 hours of the start of vancomycin therapy, 14 of 16 patients (87 percent) showed a decrease in temperature, abdominal pain and diarrhea. Diarrhea ceased completely within two days of the start of vancomycin in nine episodes, within three to seven days in six episodes, and within eight to 14 days in the remaining four episodes, and within eight to 14 days in the remaining four episodes. Diarrhea recurred in two of these patients (12 percent) when the drug inciting the initial episode of colitis was given again 42 days or more after vancomycin therapy was stopped; both patients responded again to retreatment with vancomycin. Oral vancomycin is an effective treatment of C. difficile-related colitis and diarrhea.

Simplified procedure for the routine isolation of Clostridium difficile from faeces

The use of alcohol, at a final concentration of 50%, as a selective procedure for the isolation of Clostridium difficile was compared to a selective medium containing 250 microgram /ml of cycloserine and 10 microgram /ml of cefoxitin. Of 266 faecal samples 82 were shown to be positive by one or other method. Seventy-seven (94%) of these were detected by the selective agar (SA) and 72 (88%) by the alcohol procedure (AP). Ten samples (12%) were positive only by SA and five samples (6%) by AP only. The AP was further modified so that all manipulations prior to incubation were performed on the open bench. Of 18 positive samples, 18 (100%) were detected by SA and 16 (89%) by AP.

Occurrence of toxin-producing Clostridium difficile in antibiotic-associated diarrhea in Sweden

From 1324 patients with antibiotic-associated diarrhea (AAD) 1643 stool samples were analyzed by a cell test for Clostridium difficile toxin in stool filtrates and cultivation for occurrence of C. difficile strains. In patients with no detectable toxin in their stool strains of C. difficile were isolated in 2.2% whereas when toxin was detectable, the isolation rate varied from 17% to 36%. Furthermore, there was a correlation between toxin titre in stool filtrate and production of cytotoxin in vitro by the corresponding C. difficile strains. Five clostridial strains, not belonging to the species C. difficile, were found to produce typical cytotoxin in vitro. However, five strains identified as C. difficile by biochemical reactions and gas liquid chromatography, did not produce an extracellular cytotoxin. The antibiotic susceptibility patterns of the Clostridium strains were investigated. No correlation was recognized between antibiotic resistance of isolated Clostridium strains and the AAD-inducing antibiotic penicillins and linco/clindamycin. Neither did cases of relapse of diarrheal disease after vancomycin treatment harbour C. difficile strains with increased resistance to vancomycin. It is concluded that the pathogenesis of antibiotic-associated enterocolitis is more complex than a mere intestinal overgrowth of resistant strains of C. difficile.

Relative frequency of Clostridium difficile in patients with diarrheal disease

We have studied 161 patients with diarrheal disease to determine the frequency with which Clostridium difficile occurs in such patients. C. difficile or its toxin or both were detected in stools from 19 patients (11.9%), 17 of whom had previously received antimicrobial agents. Enteric pathogens other than C. difficile were recovered less frequently, with Salmonella sp., Giardia lamblia, and Campylobacter fetus being recovered from 4.1, 2.5, and 1.3%, respectively, of the patients studied. These data suggest that C. difficile may be frequently encountered in specimens obtained from patients with diarrhea who receive antibiotics and may play a role in diarrheal disease in such patients.

Presence of Clostridium difficile toxin in guinea pigs with penicillin-associated colitis

Cecal filtrates from guinea pigs treated with penicillin contained a toxin which produced cytotoxic changes in HeLa cell cultures and was lethal to guinea pigs when administered intracecally. The cytotoxicity could be neutralized by Clostridium difficile and C. sordellii antitoxins, but not by other clostridial antitoxins. Rabbit immunization with toxic cecal extracts produced antibody which neutralized the cytotoxicity of guinea pig cecal extracts, of stool extracts from humans with antibiotic-associated colitis and of culture supernatant fluids of C. difficile. Treatment with vancomycin reduced the number of deaths and increased the survival time of penicillin-treated animals. No cytotoxin was present in cecal extracts from these guinea pigs. Gram-negative bacteremia was present in half the penicillin-treated animals, the sick ones as well as the healthy ones. Treatment with vancomycin did not decrease the incidence of bacteremia. Gram-negative bacteremia and changes in fecal flora were observed in some antibiotic-treated guinea pigs; all diseased animals, however, contained this cytotoxin. C. difficile was isolated from cecal contents of sick animals and these isolates produced the cytotoxin in vitro. The results suggest that C. difficile toxin can cause antibiotic-associated colitis in guinea pigs.

Rapid detection and presumptive identification of Clostridium difficile by p-cresol production on a selective medium

A modification of a selective medium for Clostridium difficile is described. The ability of Cl difficile to produce p-cresol from p-hydroxy phenyl acetic acid provides a means for the rapid, sensitive detection and presumptive identification of this species in faecal cultures.

Pseudomembranous (antibiotic-associated) colitis

We have come to understand the cause of antibiotic-associated pseudomembranous colitis (PMC) only in the last decade. Clostridium difficile produces the intestinal dysfunction and the characteristic finding of exudative plaques on the mucosa by elaborating a toxin in the colon. This report reviews the development of our knowledge of this disease and the rapid adoption of a rational therapy once the cause was specified. C. difficile or its toxin can be cultured or isolated from the stools of 90% of the patients with PMC. This organism is almost never found in healthy people or in any other conditions except inflammatory bowel disease, where its significance is not yet known. The detection of pseudomembranes by sigmoidoscopy establishes the diagnosis. The laboratory technics that confirm the presence of C. difficile and its toxin are being incorporated into many laboratories around the country. Treatment of diagnosed PMC is relatively simple and usually completely effective. The offending antibiotic is stopped, a proper fluid and electrolyte balance maintained, and oral vancomycin begun, 125 to 500 mg four times a day. Cholestyramine can also be used as an adjunct to this regimen. Relapse can occur in patients treated with oral vancomycin, necessitating a repeat course of therapy.

Epidemiology of antibiotic-associated colitis; isolation of Clostridium difficile from the hospital environment

Clostridium difficile is the most important cause of antibiotic-associated colitis. Using selective media, it was found that contamination with this organism was common in the environment of patients in the hospital with the disease. It was often found on floors, hoppers, toilets, bedding, mops, scales and furniture. This organism was also present on these items, but less often, in areas in which patients known to carry this hardy spore-forming organism had not been detected. Air, food and walls were negative. The organism was isolated from the hands and stools of asymptomatic hospital personnel. It was also found on surfaces in a patient's home. The importance of the various sources of the organism in its spread in the hospital is not known, and further studies are needed. It is suggested that enteric isolation precautions, and careful handwashing and cleansing of potentially contaminated surfaces and objects may be worthwhile when cases of antibiotic-associated colitis are identified.

Isolation of Clostridium difficile from the feces and the antibody in sera of young and elderly adults

Attempts were made to isolate Clostridium difficile from a total of 431 fecal specimens from 149 young and 213 elderly healthy adults, and 69 elderly adults with cerebrovascular disease but no gastrointestinal disease. C difficile was isolated from 49 specimens, and the frequency of isolation was 15.4% in healthy young adults, 7.0% in healthy elderly adults, and 15.9% in elderly adults with cerebrovascular disease. Thirty-four (about 70%) of the 49 C. difficile strains isolated produced cytotoxin which was neutralized by Clostridium sordellii antitoxin in vitro; in both young and elderly adults approximately 30% of the C. difficile isolates were nontoxigenic. The mean concentration of C. difficile in feces was 10(4.1)/g in young adults and 10(4.6)/g in elderly adults, with a range of 10(2.0) to 10(6.9)/g. Antibody against C. difficile toxin was found in most of the sera obtained from young adults carrying toxigenic C. difficile, but not in sera of elderly adults, no matter how abundant was toxigenic C. difficile in the feces.