Characterization of the genetic basis of antibiotic resistance in Clostridium difficile

By using dot blot hybridization, 69 of 102 Clostridium difficile isolates (68%) from the United States and other countries hybridized with at least one of nine DNA probes for erythromycin (Erm), tetracycline (Tet) or chloramphenicol (Cat) resistance determinants. The distribution of individual determinants in descending order of frequency was: Tet M, 32%; Erm Q, 25%; Erm FS, 18%; Tet P, 15%; Tet K, 15%; Cat P, 15%; Cat Q, 12%; Erm BP, 11%; Tet L, 7%. This is the first report of Tet P being carried by C. difficile and hitherto Erm FS has only been found within the genus Bacteriodes, while neither Tet K nor Tet L have been previously identified among the genus Clostridia. Eighteen percent of the hybridizing isolates carried multiple determinants coding for the same phenotype. A higher frequency of resistance genes was associated with prior exposure to antimicrobial agents, cytotoxin production and diarrhoea. Isolates recovered from bone marrow transplant patients carried significantly fewer antibiotic resistance genes than did those from immunocompetent general medicine patients. However, this may be due to the fact that each was located at a different site. Antibiotic resistance determinants may play a role in the virulence associated with C. difficile.

Recovery and elimination of the biotherapeutic agent, Saccharomyces boulardii, in healthy human volunteers

Saccharomyces boulardii (Sb) is a nonpathogenic yeast used to treat intestinal illnesses such as pseudomembranous colitis and antibiotic associated diarrhea. The behavior of this biotherapeutic agent in humans was determined (1) in investigating the effect of dose on the steady-state level and recovery and (2) in quantitating the effect of ampicillin on the recovery and elimination profile. As the Sb dose increased, the mean steady-state concentration of Sb increased significantly. The percentage recovery was dose independent. When a single Sb dose was administered 24 hr after beginning a course of ampicillin, there was a significant increase (P < 0.01) in both the area under the concentration versus time curve and the maximum fecal concentration compared to values obtained without ampicillin. Ampicillin increased steady-state recovery of the drug about twofold (P < 0.05) and steady-state levels about 2.4 times (P < 0.01). These studies have shown that there is a relationship between the dose and the amount of Sb recovered and that perturbation of the GI flora by ampicillin increases steady-state levels of Sb.

Diarrhea acquired in the hospital

Nosocomial diarrhea may be the second or third most common nosocomial infection, depending on the type of institution and the presence of outbreaks. Age is a major determinant of the type of cause of the diarrhea and, as a consequence, the choice of treatment. Control of nosocomial outbreaks is usually linked to prompt diagnosis and treatment of individual cases, interruption of the route(s) of transmission, and an increase in the awareness of infection-control procedures. Unfortunately, the complete elimination of nosocomial diarrhea is not feasible, and these infections will remain a challenge to us all in the future.

Elevated levels of serum immunoglobulins in asymptomatic carriers of Clostridium difficile

Serum levels of IgA, IgM, and polyvalent immunoglobulins reactive with Clostridium difficile were determined by ELISA for asymptomatic carriers (n = 5), symptomatic individuals (n = 21), and a pool of 30 "normal" individuals. Mean IgA concentrations expressed as optical density (OD +/- SD) were significantly higher (P < .001) for asymptomatic carriers (1.252 +/- 0.516) than for symptomatic patients (0.374 +/- 0.145). Mean serum IgM levels also were significantly higher (P < .001) for carriers (1.456 +/- 0.582) than for symptomatic patients (0.727 +/- 0.331), as were mean values for polyvalent immunoglobulins (2.25 +/- 0.718 for carriers vs. 1.457 +/- 0.574 for symptomatic patients; P < .05). Although the patient populations were small, the levels of immunoglobulins reactive with C. difficile antigens differed significantly. This difference might reflect the ability of the host to mount an immune response and might be a factor influencing whether a patient develops disease due to this organism. The ability to detect differences in immunoglobulin levels might also help differentiate infection from colonization.

Measurement of in vivo microsomal epoxide hydrolase activity in white subjects

An impairment or hereditary defect in microsomal epoxide hydrolase is considered a possible risk factor for drug and chemical toxicity. However, nothing is known about variability of in vivo epoxide hydrolase activity in humans. Our objectives were to develop and test a simple pharmacokinetic approach for measuring microsomal epoxide hydrolase activity in a population. After administration of carbamazepine-10,11-epoxide (100 mg), oral clearance showed a nearly linear relationship to the log (transdihydrodiol/epoxide) urine ratio in the 24- to 36-hour interval (log metabolic ratio). Intrasubject variability was assessed by administering the epoxide twice to 13 subjects (1- to 4-month interval); the log metabolic ratio did not change significantly (mean difference, 11%; paired t test, p = 0.79). In 110 healthy white adults, the log metabolic ratio ranged from 1.28 to 2.05 (mean +/- SD, 1.68 +/- 0.155). Outliers indicating enzyme-deficient phenotypes were not observed, and the frequency distribution was unimodal normal. The log metabolic ratio detected pronounced inhibition of epoxide hydrolase by valpromide (six subjects; median ratio, 0.91) and induction by phenobarbital/phenytoin (six subjects; median ratio, 2.42). We conclude that distribution of microsomal epoxide hydrolase activity in a study group can be measured pharmacokinetically by use of carbamazepine epoxide.

Correlation of immunoblot type, enterotoxin production, and cytotoxin production with clinical manifestations of Clostridium difficile infection in a cohort of hospitalized patients

To determine whether strain-specific differences in immunoblot type, enterotoxin production, or cytotoxin production correlated with clinical presentation of Clostridium difficile infection, we evaluated isolates obtained from 428 prospectively studied hospitalized patients. Of 99 isolates available for immunoblot typing, 61 were recovered from asymptomatic carriers and 38 were from patients with C. difficile-associated diarrhea. Of 17 immunoblot types, the seven types comprising the majority of isolates (82 of 99; 83%) were variably associated with disease. Neither the presence of cytotoxin in the stool nor the production of cytotoxin or enterotoxin by isolates in vitro was significantly different for symptomatic versus asymptomatic patients. Selected host factors were more predictive of symptomatic disease than was the specific infecting C. difficile strain. These results suggest that variations in the clinical severity of C. difficile infection in different patients are not solely strain-specific phenomena related to immunoblot type or to the production of cytotoxin or enterotoxin.

Influence of antibiotics on the recovery and kinetics of Saccharomyces boulardii in rats

Saccharomyces boulardii (SB) is a yeast that is used for the prevention and treatment of antibiotic-associated diarrhea and for the treatment of pseudomembranous colitis. Since SB will most commonly be used when the bacterial flora of the gastrointestinal tract have been disrupted by antibiotic treatment, the influence of different antibiotics on the kinetics and recovery of SB in feces was investigated in rats. Following a single oral dose, SB concentrations in feces were measured for periods of 1 to 6 days. Although SB is eliminated exclusively in the feces, less than 3% of the dose is recovered as viable yeast. When rats were treated with neomycin, which is active against gram-negative aerobic bacteria but not against anaerobes, no change was observed in recovery of SB when compared with recovery from untreated rats. Also, there was no change in the rate at which SB concentrations declined in feces. In contrast, treatment with clindamycin and the broad-spectrum antibiotic ampicillin, which are active against anaerobes, produced an increase in the recovery of SB of up to seven times that of controls and slowed the rate of decline of SB concentration in the feces. This antibiotic effect on SB disposition was also found when SB was administered in multiple doses. An eightfold increase in the steady-state output of SB was observed from ampicillin-treated animals. Analysis of the recovery and kinetic data showed that the primary effect of these antibiotics was to reduce the destruction of SB, probably in the cecum and colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors for Clostridium difficile carriage and C. difficile-associated diarrhea in a cohort of hospitalized patients

A prospective cohort study of 399 consecutive patients in a single ward over an 11-month period was conducted to identify risk factors for nosocomial C. difficile colonization and diarrhea. The incidence of asymptomatic carriage was 13.0/100 patient admissions and the incidence of C. difficile-associated diarrhea was 7.8/100 patient admissions. Increased age and more severe underlying illness were associated with increased risk of C. difficile carriage and diarrhea. Multivariate models adjusting for age and severity of underlying disease associated two risk factors with asymptomatic C. difficile carriage: stool softeners (relative risk [RR] = 2.04) and antacids (RR = 1.80). Five risk factors were associated with C. difficile-associated diarrhea: cephalosporin use (RR = 2.07), penicillin use (RR = 3.41), enemas (RR = 3.26), gastrointestinal stimulants (RR = 3.06), and stool softeners (RR = 1.74). C. difficile was a common nosocomial infection on this ward, resulting in asymptomatic carriage more often than diarrhea and accounting for one-fifth of all cases of nosocomial diarrhea.

Prevention of further recurrences of Clostridium difficile colitis with Saccharomyces boulardii

A patient with six documented episodes of recurrent Clostridium difficile colitis over an eight-month period is described. Relapses of colitis occurred despite treatment with vancomycin, metronidazole, bacitracin, and cholestyramine. Each recurrence appeared to begin successively closer to the end of the previous course of treatment. Four episodes were sufficiently severe to require hospitalization for rehydration. Saccharomyces boulardii, a nonpathogenic yeast, was begun prior to discontinuing vancomycin therapy for the last recurrence and was continued for three months. Serial stool cultures and assays for C. difficile showed persistence of the organism but rapid reduction of high titers of cytotoxin. No further recurrences of diarrhea or colitis were encountered while the patient was taking Saccharomyces boulardii and for 18 months of follow-up after the yeast was discontinued.

Identification of Clostridium difficile in stool specimens by culture-enhanced gas-liquid chromatography

We have developed a sensitive and specific method for the identification of Clostridium difficile in stool specimens based on the detection of metabolic breakdown products of the organism by gas-liquid chromatography after incubation of stool samples in a selective broth medium containing cefoxitin. Use of this approach to test samples from two different populations of patients at separate medical centers showed this method to be superior to plate cultures or cytotoxin testing alone for both populations. The combined results from the two patient populations showed that 225 of 226 confirmed isolates were identified correctly, resulting in a sensitivity of 99.6% and a specificity of 99.0%. This method eliminates the delay caused by subculturing for tests requiring a pure isolate. The culture phase amplifies even low numbers of C. difficile in fecal samples (due to low in vivo concentrations or delayed transport) and thus increases sensitivity. Other advantages include the ability to detect C. difficile in the mixed flora of the stool and the ability of most clinical laboratories to use this procedure. Given the complexities of the detection of C. difficile toxins and the increasing importance of this organism as a nosocomial agent, culture-based methods remain the preferred approach to screening and routine workup for cases of diarrhea.

Treatment of recurrent Clostridium difficile colitis with vancomycin and Saccharomyces boulardii

Recurrence of Clostridium difficile-associated diarrhea and pseudomembranous colitis occurs in up to 20% of patients after standard therapy. In these patients, subsequent recurrences are even more frequent. Saccharomyces boulardii, a nonpathogenic yeast, was found to be effective in preventing clindamycin cecitis recurrence in an animal model. We performed an open trial of S. boulardii to evaluate its efficacy in treating recurrences of C. difficile-associated colitis in humans. Thirteen patients with recurring C. difficile cytotoxin-positive diarrhea (who had an average of 3.6 previous recurrences) were treated with 10 days of vancomycin and a 30-day course of S. boulardii. Eleven (85%) had no further recurrences. S. boulardii may have a role in treating recurrent C. difficile diarrhea and colitis.

Prevention of antibiotic-associated diarrhea by Saccharomyces boulardii: a prospective study

Saccharomyces boulardii, a nonpathogenic yeast, has been widely used in Europe to prevent antibiotic-associated diarrhea (AAD). We performed a prospective double-blind controlled study to investigate AAD in hospitalized patients and to evaluate the effect of S. boulardii, a living yeast, given in capsule form concurrently with antibiotics. Over 23 mo, 180 patients completed the study. Of the patients receiving placebo, 22% experienced diarrhea compared with 9.5% of patients receiving S. boulardii (p = 0.038). Risk factors found to be associated with AAD were multiple antibiotic combinations (containing clindamycin, cephalosporins, or trimethoprim-sulfamethoxazole) and tube feeding. Clostridium difficile, an anaerobe found in the stools of most patients with pseudomembranous colitis, was variably associated with AAD. We evaluated the role of C. difficile in AAD in the study population and found no significant association between the presence of C. difficile or cytotoxin with AAD. Approximately 33% of the patients without diarrhea harbored at least one C. difficile-positive stool and nearly 50% of these patients had detectable cytotoxin. Similar values were obtained in patients with diarrhea. Of C. difficile-positive patients, 31% (5/16) on placebo developed diarrhea compared with 9.4% (3/32) on S. boulardii; this difference was not statistically significant (p = 0.07). There were no discernable adverse effects of yeast administration. We conclude that S. boulardii reduces the incidence of antibiotic-associated diarrhea in hospitalized patients.

Nosocomial acquisition of Clostridium difficile infection

We studied the acquisition and transmission of Clostridium difficile infection prospectively on a general medical ward by serially culturing rectal-swab specimens from 428 patients admitted over an 11-month period. Immunoblot typing was used to differentiate individual strains of C. difficile. Seven percent of the patients (29) had positive cultures at admission. Eighty-three (21 percent) of the 399 patients with negative cultures acquired C. difficile during their hospitalizations. Of these patients, 52 (63 percent) remained asymptomatic and 31 (37 percent) had diarrhea; none had colitis. Patient-to-patient transmission of C. difficile was evidenced by time-space clustering of incident cases with identical immunoblot types and by significantly more frequent and earlier acquisition of C. difficile among patients exposed to roommates with positive cultures. Of the hospital personnel caring for patients with positive cultures, 59 percent (20) had positive cultures for C. difficile from their hands. The hospital rooms occupied by symptomatic patients (49 percent) as well as those occupied by asymptomatic patients (29 percent) were frequently contaminated. Eighty-two percent of the infected cohort still had positive cultures at hospital discharge, and such patients were significantly more likely to be discharged to a long-term care facility. We conclude that nosocomial C. difficile infection, which was associated with diarrhea in about one third of cases, is frequently transmitted among hospitalized patients and that the organism is often present on the hands of hospital personnel caring for such patients. Effective preventive measures are needed to reduce nosocomial acquisition of C. difficile.

Rectal swab cultures for Clostridium difficile surveillance studies

We compared the recovery of Clostridium difficile from hospitalized patients by two collection methods: rectal swabs and stool cultures. Rectal swab cultures were as sensitive as stool cultures and were more easily obtained. Transport of swabs in an anaerobic VACUTAINER system resulted in longer survival times compared with transport in Amies medium.

Suppression by Saccharomyces boulardii of toxigenic Clostridium difficile overgrowth after vancomycin treatment in hamsters

Saccharomyces boulardii prevented the development of high counts of Clostridium difficile, high titers of toxin B, and positive latex agglutination tests after cessation of vancomycin treatment for hamsters. The protocol used was designed to stimulate relapse of human C. difficile-associated colitis. S. boulardii was protective in this model.

Erb/Duchenne's palsy: a consequence of fetal macrosomia and method of delivery

Methods of delivery, maternal and neonatal characteristics were examined to determine their role in the occurrence of Erb/Duchenne's palsy. Data from 210,947 Washington state birth certificates from 1980 through 1982 were examined. The incidence was 50.2 cases of Erb's palsy per 100,000 live births. A case control study design was used to analyze 106 cases and 386 controls by both univariable and multivariable analysis. Birth weight was shown to be a significant risk factor regardless of which method of delivery was used. A high birth weight infant (4001-4500 g) had 2.5 times the risk of incurring an upper brachial plexus injury compared with normal size infants (2501-4000 g). The risk for infants greater than 4500 g increased another tenfold (OR = 21.0). When birth weight was controlled for in the analysis, midforceps (OR = 18.3), vacuum extraction (OR = 17.2), and low forceps (OR = 3.7) remained significantly associated with the Erb's palsy. Delivery by cesarean section was associated with a significant protective effect (OR = 0.5) compared with instrumental vaginal delivery. These data demonstrate a high risk for serious birth injury associated with instrumental midpelvic delivery.

Review of Clostridium difficile-associated diseases

Clostridium difficile has recently become recognized as an important nosocomial pathogen. This review summarizes what is known about the isolation of the organism, the spectrum of clinical disease, virulence factors, treatments, and methods of prevention. Risk factors for C. difficile disease are also discussed. The most important risk factor is the use of certain antibiotics (ampicillin, cephalosporins, and clindamycin). C. difficile is associated with 96% to 100% of cases of pseudomembraneous colitis, 60% to 75% of antibiotic-associated cases of colitis, and 11% to 33% of antibiotic-associated cases of diarrhea. Other risk factors include gastrointestinal manipulations, advanced age, female sex, inflammatory bowel disease, cancer chemotherapy, and renal disorders. Hospital outbreaks of C. difficile disease are examined. Data from nosocomial outbreaks support transmission of C. difficile by contaminated fomites and hand carriage by hospital personnel.

Risk factors for fireworks-related injury in Washington State

To determine the frequency and effects of and risk factors for fireworks -related injury, we identified all 146 persons who were injured by fireworks and sought emergency care during the 1983 July 4 holiday in the Seattle area. The mean charge for medical care for the injuries received was +562; 7.1% of those injured required hospitalization. In a matched-pair case-control study, use of either of two fireworks types-- firecrackers or aerial devices--was significantly associated with injury (odds ratios [ORs], 3.3 and 2.9, respectively; 95% confidence intervals [CI], 1.2, 8.5, and 1.2, 6.6, respectively). Also associated with injury were several fireworks misuse behaviors, including lack of adult supervision of children (OR, 11.5; CI, 2.8, 100.6). We conclude that fireworks cause serious injuries that theoretically could be prevented by behavioral changes or decreased availability of high-risk fireworks devices.