- Email: [email protected]
Clostridium difficile infection in children
Clinical Microbiology Newsletter April 1, 1999
Vol. 21, No. 7
Karin L. McGowan, Ph.D. Department of Pediatrics, Division of infection Diseases
Howard A. Kader, M.D. Divisions of Gast~entero~ogy and attrition The Children’s Hospital of Philadelphia University of Pen~syiv~ia School of Medicine Philadelphia, PA 19104
Introduction Clos~~diu~ di~cile is an impo~ant cause of pediatric diarrhea. The diagnosis of a C. dt~cile infection is impo~ant to establish since the disease can vary from acute, self-limited diarrhea to toxic megacolon associated with peritonitis, sepsis, shock, and death. Characteristic signs and symptoms of a C. diflcile infection include profuse diarrhea, abdominal cramps, nausea, vomiting, fever, abdominal tenderness, and passage of bloody, mucus-containing stool and may include systemic toxicity. Anemia from ongoing gastrointestinal (GI) blood losses or fulminant colitis, and diarrhea-related dehydration may become severe in children (1,2). The extent and degree of illness is dramatically worse in children when compared to adults. Institution of approp~ate antimicrobial therapy can be life-saving, especially in fulminant enterocohtis. In adults, C. dzjkile is well established as the primary cause of pseudomembranous colitis (PMC) and antibioticassociated colitis and is thought to account for 25% of antibiotic-associated diarrhea (3). Pediatric patients at risk for C. difficile infection are not only those treated with antibiotics but also special groups of patients with no present or recent history of antibiotic use. These include children who have
Clinical Mhobiology
Newsletter 21:7,1999
neutropenia due to hematologic malignancies such as leukemia, those who are i~unosuppressed due to bone marrow or solid organ transplant, those with hypog~maglobulinemia, infl~mato~ bowel disease, or Hirschsprung’s diseaserelated enterocolitis. Hirschsp~ng’s disease, also called congenital aganglionic megacolon, is characterized by the absence of submucosal ganglion cells in the colon. This results in an inability to propel stool and is the most common cause of lower intestinal obstruction in the neonate. The lack of stool passage can result in bacterial proliferation, severe persistent or recurrent diarrhea, and ultimately enterocolitis. In neonates with this disorder, the mortality rate is 75%. In most cases, the enterocolitis associated with Hirschsprung’s disease is caused by C. dijjicile (4-6). Infants and children are more susceptible to diarrhea-related dehydration and its associated morbidities than the older child, adolescent, or adult. C. dij&iEe toxin B has been detected in the blood and ascites fluid of children who developed fatal cases of PMC with underlying Hirschsprung’s disease or hematologic malignancies. The pediatric gastroenterologist, therefore, is sometimes placed in a difficult clinical situation while awaiting the return of C. diSficiZe toxin results. He or she is faced with the decision to continue supportive management or to perform a coionoscopy if there has been significant blood loss. This situation rarely occurs with adult patients.
to colonize the GI tract and to affect both the small and large bowel. It has been described as the most common agent causing pseudomembranous colitis, and recently, has been considered to be the only cause of true pseudomembranous colitis. C. di~ci~e, however, at most accounts for only 25% of antibioticassociated diarrhea ( I ,7). The bacterium produces two toxins that are involved in the pathogenesis of this diarrhea. Toxin A, an enterotoxin that causes hemorrhage and fluid secretion in animal models, is believed to be the primary toxin responsible for producing clinical symptoms (3). The second toxin, toxin B, is a cytotoxin detected by its cytopathic effects in cell culture. To detect toxin A, an enzymelinked immunosorbant assay (EIA) specific for the toxin is commonly used. EIA provides inexpensive, sensitive and specific (71 to 99%, and 91 to lOO%, respectively), non-invasive means to identify toxin A in stool specimens (8,9). Most toxin A assays, however, were validated in clinical laboratories by comparing toxin A detection to the
In This Issue ~i~~~~iu~ dif~~~~~Infeetion in Children . . . . . . . . . . . . . . . . . . .49 A review of the special issues and concerns related to C. difficile disease in pediatric patients
Microbiology Director Salary Survey . . . . . . . . . . . . . . . . .54
Organism Characteristics
Where do you fit?
C. dijj%ile is an anaerobic, grampositive, endospore-forming rod known
Upcoming Meetings Announcements . . . . . . . . . * . . . .55
0 1999 Elsevier Science Inc.
0196-4399199 (see frontmatter)
l
49
previously accepted toxin B cell culture assay. This comp~ison assumes that toxin A and toxin B are produced equally in every C. d#kile infection, an assumption that is now being debated in pediatric settings. Toxin B detection through cytotoxin neutralization testing has a reported sensitivity of 67 to 99% and a specificity of 95 to 99% but it is more expensive, labor intense, and can require 48 h to compfete (IO). First described in animal studies, a toxin-receptor mechanism is believed to account for human C. difSicile disease. The receptor, neurokinin- 1, is required for C. difficile toxin A to induce human enteritis. Studies have demonstrated, however, that the enzymatic activity of both toxins A and B was the main determinant of cytotoxic potency and the difference in receptor binding contributed to a lesser degree (11,12). Issues Related to Infants and Children Pediatric and adult C. dificile infections share many similar features, however, there are specific differences in children that makes this disease entity more formidable and challengiiig for the pediatrician. The epidemiology of C. d@kile in children is frequently divided into two groups. In neonates (c 6 weeks) and infants less than two years of age, toxin-producing strains of C. di~ciie are found in the stool but the patients are asymptomatic thus representing a carrier state (13). Colonization of neonates with C. difficile occurs within a few days of birth, usually from environmental sources rather than from maternal transmission (14). Free toxins, both Aand B, have been detected in the feces of asymptomatic neonates and infants. In children greater than two years of age, the epidemiology is similar to that seen in adults. The prevalence of the C. dificile carrier state in healthy, asymptomatic outpatients when detect-
ed by culture is reported to be as high as 70% in infants less than 18 months of age, 3% in children, and 1 to 3% in adults. This high asymptomatic carrier rate in infants often makes it difficult to interpret the clinical significance of detecting the organism or even the presence of toxins A or B in this age group without significant clinical disease. Studies of toxin B production in children with C. d~~ciie colonization have revealed that 22 to 28% of infants six days to six months of age, carry toxinproducing strains, whereas after six months of age, approximately 50% of the colonizing strains produce toxin B (15). Another study found that in these asymptomatic patients, many different serotypes of C. di~ci~e colonize the infant intestine and that 62.5% of the C. disficile isolates secrete neither toxin A or B, 37.5% secrete both toxins, and 3% secrete toxin A alone (16). Toxin B detection, however, has been reported to be more frequent in infants with diarrhea than in children over one year of age with diarrhea. Colonization with C. di~ciZe is signi~cantly lower in infants less than one year of age treated with antibiotics than children over one year of age. In addition to other seasonal infectious processes, we suspect C. dificile infection in children whenever there has been significant symptomatic diarrhea: an ill-appearing patient with severe dehydration and/or bloody stools with mucus. C. di$Jicile may be thought of classically as a nosocomial infection, but the endospores are ubiquitous making places where children congregate outside of hospitals, such as daycare centers, likely locations to acquire this infection (17). We would evaluate significant, symptomatic diarrhea for inpatients and outpatients similarly, but would be more sensitive to the circumstances in which C. difficile is more likely to occur. In our practice, this
applies to children younger than two years ~though not every child younger than six months may receive treatment for C. difsicile. If all other age-group appropriate etiologies for diarrhea have been excluded, such as enteric bacterial pathogens, milk-soy protein intolerance, rotavirus, etc., and either the C. di#iciZe toxin assay is positive or the patient remains symptomatic, then we recommend reagent. It has been reported that infants fed breast milk are less likely to develop C. dificile infection. Fewer breast-fed infants are colonized by C. di#kile than are bottle-fed infants at six weeks of age (21 vs. 47%) and six months of age (19 vs. 39%) (15). A Nigerian study supported the protective benefit of breast milk when the authors reported that the frequency of toxin B positivity in children fed formula alone was SO%, 19% in those taking both breast milk and formula, and 17.5% in those taking only breast milk ( 18). Immunoglobulin A or other non-immunoglobulin components secreted in breast milk are thought to inhibit C. di~cile toxin-A binding and may explain why breastfeeding is protective against disease and reduces toxin detection. This breast milk factor, however, does not prevent the cytotoxic activity of toxin B (19). Although adherence of the C. di$kiZe toxins to receptors is believed to be an irnpo~~t virulence factor in adult diarrhea, it may not be important in pediatric diarrhea since infants less than six months of age do not express toxin receptors on their enterocytes (20). A recent study of nosocomial diarrhea demonstrated that C. d@cile accounted for 3% of all in-patient pediatric diarrhea. In that study, C. difficile was, however, the most common pathogen identi~ed and occurred in 17.5% (7 of the 40 inpatients) in whom a pathogen was identified (21). Other studies have reported a 14.8% incidence of toxin B in C. dificile-
NOTE: No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. No suggested test or procedure should be carried out unless, in the reader’s judgment, its risk is justified. Because of rapid advances in the medical sciences, we recommend that the independent verification of diagnoses and drug doses should be made. Discussions, views and recommendations as to medical procedures, choice of drugs and drug dosages are the responsibility of the authors. Chid Micro&log? Newslener (ISSN 01964399) is issued twice monthly in one indexed volume per year by Elsevier Science Inc., 655 Avenue of the Americas, New York, NY 10010. Subscription price per year: for customers in Europe, The CIS, and Japan: NLG 423.00: for customers in all other countries: US$Z43.00. Periodical postage paid at New York, NY and at additional mailing offices. Postmaster: Send address changes to Cfinicd Microbiology NewsZe#e~ Elsevier Science Inc., 655 Avenue of the Americas, New York, NY KXJIO.For customer service, phone (212) 633-395O;TGLL-FREE for customers in the United States and Canada: I-888-4ES-INFO (1888-437-4636) or fax: (212) 633-3860.
50
0196-4399199 (see frontmatter)
0 IQ99 Else&r Science Inc.
Clinical Microbiology Newsletter 21:7,1999
related nosocomial diarrhea, and as high as 5 1 and 61% for non-antibioticand antibiotic-related diarrhea, respectively, in one study from Thailand (18,22). The incidence of C. difSicile nosocomial infections reportedly does not differ between adult and pediatric institutions.
Special Pop~ations Studies have shown that adults receiving chemotherapy for cancer are at increased risk of acquiring C. di$Gcileassociated diarrhea, even in the absence of antibiotics. It is believed that antineoplastic chemotherapy alters normal bowel flora in adults and causes extensive disruption of the intestinal mucosa, providing an excellent environment for C. dificile colonization and disease (23). For reasons not yet understood, this does not appear to be true in pediatric oncology patients receiving chemotherapy. Except in the case of a hospital outbreak, C. difSicile is not a pathogen in pediatric oncology patients (24). It is important that diarrhea not be accepted as a normal symptom of cancer chemotherapy in pediatric patients and that stool specimens be appropriately tested for all bacterial, viral, and parasitic etiologies. Because they continually receive antibiotics and are frequently hospitalized, children with cystic fibrosis (CF) would appear to be prime candidates for C. dificile diarrhea. Despite the risk factors, prospective studies have shown that disease with C. diJjTcileis unusual in children with CF (25,26). While as many as 22% of children with CF are colonized with toxigenic strains of C. di~cile and cytotoxin can be detected in the stool of most colonized patients, most CF patients have no GI symptoms. While reasons for this observation are still unproven, it is interesting to note that the normal GI flora in stool cultures from children with CF is much more likely to include organisms that are known to have inhibitory effects on C. di~c~le such as Pseudomo~~, Stap~~Lococcus, Lactobacillus, and Enterococcus species. This flora does not, however, explain why detectable cytotoxin in the stool of CF patients fails to cause symptoms.
Clinical and Laboratory Diagnosis When examined endoscopically for evidence of C. d@cile infection, adult patients show classic lesions at multiple Clinical Microbiology Newsletter 2h7.1999
sites on the mucosal surface. As a result, adults rarely require biopsy for histologic diagnosis of this pathogen. In children, however, there is a wide variety of possible endoscopic changes ranging from nodal-appe~ing mucosa to dramatic, characteristic mucosal findings. Lesions may be localized to or spare the rectum and result in segmental colitis or even pancolitis. Visible lesions, when present, may consist of patchy or diffuse erythema or may show the classical pseudomembranes that adhere to the colonic mucosa. They can range in size from 2 to 10 mm and are raised, yellowish, or grayish-white plaques surrounded by edema and erythema. The histological feature of C, difficile infection in children is a focal explosive mucosal lesion revealing a mushroom-like mass of cellular debris, that is referred to as a “volcano lesion.” These lesions exude fibrinous material, mucus, and neutrophils, which stream out of the underlying damaged crypts (13). Due to the endoscopic variability seen in pediatric C. dz#Gziledisease, biopsy is frequently required to make the diagnosis of PMC. It is not unusual for patients with normalappearing mucosa to have microscopic foci of disease below the surface in the lamina propria. Fortunately, the diagnosis of C. difltile is made easily by the detection of toxin A and/or toxin B produced by this organism. Cultures were once thought to be the most sensitive method whereas detection of toxin B by cell culture assay was felt to be most specific (27). Toxin A is an enterotoxin that causes mucosal inflammation, mucus discharge, increased vascular permeability, fluid secretion, epithelial necrosis, abdominal cramping, and gut motility abnormalities. Toxin A has been reported to be the primary mediator of illness (28). Toxin B is a cytotoxin that is ten-fold more potent than toxin A in causing mucosal damage (29). It is associated with diarrhea, hemorrhagic colitis, and cytopathic effects. To insure optimal detection, an adequate specimen must be obtained and properly handled. While the organism itself is hardy and resistant to desiccation, the toxins are less hardy and can deteriorate at room temperature. The stool must be liquid (formed stools are not acceptable), kept refrigerated between 2 to 8°C and transported to the laboratory on ice or frozen. These trans0 1999 Elsevier ScienceInc.
port requirements may pose significant problems for laboratories or physicians’ offices that refer stool specimens to other institutions or commercial laboratories for toxin detection. The relative importance of each toxin in pediatric diarrhea has not been fully established. It has been suggested by studies performed in adults that C. difJiciZetypically produces either both toxins concurrently or neither toxin (28). By C. di~cile culture, several studies have demonstrated that certain strains produce varying amounts of toxin A or B or none at all (30). Many hospital laboratories do not perform assays for both toxins on submitted stool specimens. Consequently, it is important to determine which C. dzfficile toxin(s) are prevalent and responsible for pathogenesis to best determine which toxin(s) should be detected. The primary C. dificile toxin related to disease in children remains controversial. The American Academy of Pediatrics (AAP): I997 Red Book: Report of the Committee on Infectious Diseases addresses this issue in its recommendation to test for C. dificile toxin B alone or for both toxins A and B (1). Failure to identify C. difJicile in the early stages of infection may result in substantial worsening of the disease since pediatricians may treat the diarrhea with antibiotics or antisecretory agents. Furthermore, the subsequent evaluation for patients with negative bacterial cultures and C. diflcile toxin-negative chronic diarrhea frequently includes radiologic and endoscopic studies. Failure to diagnose C. dificile in these patients may result in substantially increased and unnecessary costs. These additional studies also result in increased patient risk and discomfort. The implications of a study recently completed at our hospital are that neither the toxin A nor toxin B assay alone identifies all pediatric patients with C. disficile infection (3 1). Testing for only toxin A would have detected C. di~cile 50% of the time while testing for toxin B alone would have detected 82% of the infections (Table 1). There was no statistical significance found between toxin A and B detection in children younger than one year, however, there was statistical significance in ages 1 to 16 years and those >16 years (p=O.OOOl) (3 1). The data from our study supports the American Academy of Pediatrics 0196~3~~
(see frontmatter)
51
recommendations to test for C. dz$IciZe toxin B at a minimum. We would encourage those testing stools from children for toxin A alone to consider testing for toxin B, especially if the toxin A test is negative. The cost effectiveness of an improved diagnostic algorithm must be considered if patient care is to be optimized. A laboratory decision to identify only toxin A on specimens from children may be inappropriate. Results should be accompanied by a statement stating that a significant percentage of C. difSicile infections will be undetected by a single toxin assay. Given such a disclaimer, to address the problem of under-diagnosis, physicians might routinely order assays for both toxin A and B or order the second toxin if the first test is negative. Further studies are needed to determine if both toxins cause disease in the pediatric population and what laboratory testing approach might be most efficient and cost effective. We support the detection of both toxins in children to best diagnose this infection in a non-invasive manner. Since some health maintenance organizations may only approve reimbursement for toxin A detection, physicians who order C. diflicile toxin assays should understand the limitations of each assay available in their region. Previously, C. difficile detection by culture, even in the absence of cytotoxin detection in certain diarrhea1 syndromes, was considered evidence to treat (32). The role of culture is still controversial as one study showed that pseudomembranous colitis detected by endoscopy was associated with 5 1% of culture and toxin B assay positive stool, while 11%
of patients were culture positive but toxin B negative (27). Both groups responded similarly to metronidazole or vancomycin therapy. Toxin A was not evaluated in this study. C. dz~c~le culture is still important in laboratory research and epidemiology to identify the different strains and their virulence patterns
Antibiotic Treatment and Other Therapies Initial treatment of C. dz@Ale disease involves discontinuing the antibiotic therapy that initiated the disease and restoring lost fluids and electrolytes. For approximately 25% of patients, these measures will be sufficient. If symptoms do not resolve, or if the patient is debilitated or severely ill, then specific antibiotic therapy is used. Therapy for C. d~~ciZe primarily involves the use of metronidazole or vancomycin which are bactericide for this organism. C. d@tile is highly susceptible to vancomycin and usually, but not always, susceptible to metronidazole. V~comycin, however, is substantially (50 times) more expensive than metronidazole (33). Both medications are administered orally for 10 to 21 d and both have similar efficacy and relapse rates (34). Side effects of gastrointestinal discomfort, finger numbness and tingling, nephrotoxicity, and a metallic taste are more common with the use of metronidazole since it is systemically absorbed. Vancomycin is not systemically absorbed so it acts directly on the organism in the lumen of the intestine. Multiple relapses are an unfortunate sequel following treatment of C. d@icile pseudomembranous colitis and occurs with 10 to 20% of pediatric cases. Patients who relapse usually respond to
re-treatment with vancomycin but there are reports of children who have relapsed after multiple courses of both vancomytin and metronidazole. Relapses manifest as chronic diarrhea or repeated pseudomembranous colitis. During both forms of relapse, C. di@ciZe toxins reappear in the stool. Therapies other than antibiotics have been used in refractory or recurrent C. dijjicile infections. These treatments are directed at over-populating the gastrointestinal tract with nonpathogenic intestinal organisms, at reducing the number of C. di~cile org~isms, or at binding the toxins. Anion-exchange resins, such as cholestyramine, directly bind to the toxins of C. di~ciZe and are a treatment option in mild or moderate disease but are not as effective as antibiotics in cases of severe disease. The major drawback with use of these resins is that they also bind to vancomycin and cannot be used in combination with this antibiotic. Several studies have attempted to prevent recurrent C. difficile disease by oral administration or by enema introduction of nonpathogenic organisms into the gastrointestinal tract to compete with the C. difficile. Preparations of lactobacilli or the nonpathogenic yeast Saccharomyces boulardii are the most popular. Both are given in capsule form, can be taken safely, and only transiently colonize the GI tract. Because S. boulurdii is unaffected by antibiotics, an ad~tional advantage is that it can be given in combination with antibiotic therapy. The use of S. boulardii and Lactobacillus GG in symptomatic infants who were toxin positive resulted in significant improve-
ment and prevention of relapse (33-36).
Conclusion Table 1. Frequency of detection of C. diJt?cile toxins by patient age”
No.
Positive for
Positive for
Positive for
Samnles
toxin A onlv
toxin B only
toxins A and B
<6 months old
28
8 (28.6%)
5 (17.8%)
15 (53.6%)
6 months to ~1 year
32
9 (28.1%)
17 (53.1%)
6 (18.8%)
1 year old to ~16 years
182
29 (15.9%)
92 (50.5%)
61 (33.5%)
216 years
34
5 (14.7%)
19 (55.9%)
10 (29.4%)
All ages
276
51 (18.5%)
133 (48.2%)
92 (33.3%)
Age Grouvs
“Data from reference 31
52
01964399/99 (see frontmatter)
0 1999 Elsevier Science Inc.
C. diflcile is more problematic in children than adults because of problems in maintaining hydration and issues related to rapid weight loss due to diarrhea. Unlike adults who have reserve energy and nutrient stores, in infants and young children, these can rapidly become depleted from C. di~cile diar-
rhea. Controversy exists about the pathogenicity of this organism in the infant population due to their high colonization rate yet anecdotally, treatment of these infants results in resolution of symptoms. Further studies in this population group are warranted. In pediatric C. di$cile disease, both toxins have
Chical Microbiology Newsletter 21:7,1999
been implicated in disease and vary in rate of detection. The assumption that both toxins are produced equally in all symptomatic C. diflcile infections recently has been challenged. Until further studies substantiate or disprove these findings and a cost-effective algorithm is determined, tests to detect both toxin A and toxin B should be routinely performed when C. diflcile is a suspected cause of pediatric diarrhea. References 1. Peter, G. (ed.). 1997. Clostridium dzficile, p. 177-178. in: Ame~can Academy of
Pediatrics Red Book: Report of the Committee on Infectious Diseases. 24th ed. American Academy of Pediatrics, Elk Grove Village, IL. 2. Qualman, S.J. et al. 1990. Clostrid~~ dificile invasion and toxin circulation in fatal pediatric pseudomembr~ous colitis. Am. J. Clin. Pathol. 94:410-416.
Clostridium, p. 580-581. In Murray P.R. et al. (eds,). Manual of Clinical Microbiology. 6th ed. ASM Press, Washington, DC.
11. Castagliuolo, I. et al. 1998. Neurokinin1 (NK-1) receptor is required in Clostridium d~~cile-induct enteritis. J. Clin. Invest. 101:1547-1550. 12. Chaves-Olarte, E. et al. 1997. Toxins A and B from Clost~dium dijkile differ with respect to enzymatic potencies, cellular substrate specificities, and surface binding to cultured cells. J. Clin. Invest. 100:1734-1741. 13. Mitty, R.D. andT. LaMont. 1996. Pseudomembranous colitis. p. 726-739. In: Walker, W.A. et al. (eds). Pediatric Gastroenterointestinal Disease: Pathophysiology, Diagnosis, Management. 2nd ed., Vol. 1. Mosby, Philadelphia. 14. Larson, H.E. et al. 1984. Epidemiology of Clostridi~ dijjkile in infants. J. Infect. Dis. 146:727-733.
3. Lyerly, D.M., H.C. Krivan, andT.D. Wilkins. 1988. Clostridi~ dificile: its disease and toxins. Clin. Microbial. Rev. 1:1-l%
15. Tullus, K. et al. 1989. Intestinal colonization with Clostridium difficile in infants up to 18 months of age. Eur. J. Clin. Microbial. and Infect. Dis. 8:390-393.
4. Thomas, D.F.M. et al. 1986. Enterocolitis in Hirshsprung’s disease: a controlled study of the etiologic role of Clostridium digicile. J. Pediatr. Surg. 21:22-25.
16. Collignon, A. et al. 1993. Heterogenicity of Clost~dium d@cile isolates from infants. Eur. J. Ped. 152:319-322.
5. Thomas, D.F.M. et al. 1982. Association between Clostridium d@cile and enterocolitis in Hirschsprung’s disease. Lancet i:78-79. 6. Hardy, .%I?,R. Bayston, and L. Spitz. 1993. Prolonged carriage of Clostridium difsicile in Hi~chsp~ng’s disease. Arch. Dis. Child. 69:221-224. 7. Whitehead, R. 1995. Primary inflammatory disorders and disturbances of digestive function. p. 614-616. In: Whitehead, R. (ed.) Gastrointestin~ and Esophageal Pathology, 2nd ed. Churchill Livingstone, New York. 8. Whittier, S. et al. 1994. Evaluation of four commercially available enzyme immunoassays for laboratory diagnosis of Clastridium difJicile-associated diseases. J. Clin. M~crobiol. 31:2861-2865. 9. Doem, G.V., R.T. Coughlin, and L. Wu. 1992. Laboratory diagnosis of Clostridium d@cile-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. J. Clin. Microbial. 30:2042-2046. 10. Onderdonk, A.B. and S.D. Allen. 1995.
Clinical Microbiology Newsletter 21:7,1999
17. Kim, K. et al. 1983. Outbreaks of diarrhea associated with Clostridium dificile and its toxin in day-care centers: evidence for peon-to-arson spread. J. Peds. 102:376-382. 18. Emeruwa,A.C. and J.U. Oguike. 1990. Incidence of cytotoxin producing isolates of Clostridium dificile in faeces of neonates and children in Nigeria. Microbiologica 13:323-328. 19. Rolfe, R.D. and W. Song. 1995. Immunoglobulin and non-immunoglobulin components of human milk inhibit Clostridium d@cile toxin A-receptor binding. J. Med. Microbial. 42:10-19. 20. Gonzalez-Valencia, G., 0. Munoz, and J.F. Torres. 1991. Toxigenicity and adherence in Clostridium d@cile strains isolated from patients with and without diarrhoea. Arch Invest. Med. 22: 189196. 21. Meropol, S.B., A.A. Luberti, and A.R. DeJong. 1997. Yield from stool testing of pediatric inpatients. Arch. Pediatr. Adolesc. Med. 151:142-145. 22. Won~a~ch, S. et al. 1990. Clostridi~ dificile associated disease in Thailand. SE Asian J. Trop. Med. and Pub. Health. 21:367-372. 23. Anand, A. and A.E. Glatt. 1993. Clostridium dz$kile infection associated
0 1999 Ekevier Science Inc.
with antineoplastic chemotherapy: a review. Clin. Infect. Dis. 17: 109-l 13. 24. Burgner, S.S. et al. 1997. A prospective study of Clostridium dificile infection and colonization in pediatric oncology patients. Pediatr. Infect. Dis. J. 16: 113l1134. 25. Welkon, C.J. et al. 1985. Clostridium dificile in patients with cystic fibrosis. AJDC 139:805-808. 26. Wu, T.C., V.P. McCarthy, and V.J. Gill. 1983. Isolate rate and toxigenic potential of Clostridium d@kile isolates from patients with cystic fibrosis. J. Infect. Dis. 148:176. 27. Gerding, D.N. and J.S. Brazier. 1993. Optimal methods for identifying Clostridium dificile infections. Clin. Infect. Dis. 16 Suppl4:S439-S442. 28. Fekety, R. 1995. Antibiotic-associated colitis. p. 978-987. In: Mandell, G. L. et al. (eds). Principles and Practice of Infectious Fisease. 4th ed. Churchill Livingstone, New York. 29. Riegler, M. et al, 1993. Clostridium dificile toxin B is more potent than toxin A in damaging human colonic mucosa in vitro. Gastroenterology 104:A770. 30. Bare, MC. et al. 1992. Effects of antibiotics and other drugs on toxin production in Clostridium d$tkile in vitro and in vivo. Antimicrob. Agents Chemother. 36:1332-1335. 31. Kader, H.A. et al. 1998. Detection of Clostridium dificile toxins A or B alone will not diagnose all Clostridium dificile diarrhea in pediatric patients, Gastroenterology 115:1-7. 32. Lashner, B.A. et al. 1986. Clostridium disficile culture-positive toxin-negative diarrhea. Am. J. Gastroenterol. 81:940943. 33. Fekety,R. andA.B. Shah. 1993. Diagnosis and treatment of recurrent Clostridium dif&ile colitis. JAMA 269:71-75. 34. Talbot, R.W., R.C. Walker, and R.W. Beart Jr. 1986. Changing epidemiology, diagnosis, and treatment of Clostridium d~~cile toxin-associated colitis. Brit. J. Surg. 73:457-460. 35. Buts, J.P., G. Corthier, and M. Delmee. 1993. Succharomyces boulardii for Clostridium di$icile-associated enteropathies in infants. J. Ped. Gastroenterol. and Nutr. 16:419-425. 36. Gorbach, S.L., T.W. Chang, and B. Goldin. 1987. Successful treatment of relapsing Clostridium dificile colitis with ~ctobacillus GG. Lancet 2: 15 19.
0196-4399199 (see frontmatter)
53
Vol. 21, No. 7
Karin L. McGowan, Ph.D. Department of Pediatrics, Division of infection Diseases
Howard A. Kader, M.D. Divisions of Gast~entero~ogy and attrition The Children’s Hospital of Philadelphia University of Pen~syiv~ia School of Medicine Philadelphia, PA 19104
Introduction Clos~~diu~ di~cile is an impo~ant cause of pediatric diarrhea. The diagnosis of a C. dt~cile infection is impo~ant to establish since the disease can vary from acute, self-limited diarrhea to toxic megacolon associated with peritonitis, sepsis, shock, and death. Characteristic signs and symptoms of a C. diflcile infection include profuse diarrhea, abdominal cramps, nausea, vomiting, fever, abdominal tenderness, and passage of bloody, mucus-containing stool and may include systemic toxicity. Anemia from ongoing gastrointestinal (GI) blood losses or fulminant colitis, and diarrhea-related dehydration may become severe in children (1,2). The extent and degree of illness is dramatically worse in children when compared to adults. Institution of approp~ate antimicrobial therapy can be life-saving, especially in fulminant enterocohtis. In adults, C. dzjkile is well established as the primary cause of pseudomembranous colitis (PMC) and antibioticassociated colitis and is thought to account for 25% of antibiotic-associated diarrhea (3). Pediatric patients at risk for C. difficile infection are not only those treated with antibiotics but also special groups of patients with no present or recent history of antibiotic use. These include children who have
Clinical Mhobiology
Newsletter 21:7,1999
neutropenia due to hematologic malignancies such as leukemia, those who are i~unosuppressed due to bone marrow or solid organ transplant, those with hypog~maglobulinemia, infl~mato~ bowel disease, or Hirschsprung’s diseaserelated enterocolitis. Hirschsp~ng’s disease, also called congenital aganglionic megacolon, is characterized by the absence of submucosal ganglion cells in the colon. This results in an inability to propel stool and is the most common cause of lower intestinal obstruction in the neonate. The lack of stool passage can result in bacterial proliferation, severe persistent or recurrent diarrhea, and ultimately enterocolitis. In neonates with this disorder, the mortality rate is 75%. In most cases, the enterocolitis associated with Hirschsprung’s disease is caused by C. dijjicile (4-6). Infants and children are more susceptible to diarrhea-related dehydration and its associated morbidities than the older child, adolescent, or adult. C. dij&iEe toxin B has been detected in the blood and ascites fluid of children who developed fatal cases of PMC with underlying Hirschsprung’s disease or hematologic malignancies. The pediatric gastroenterologist, therefore, is sometimes placed in a difficult clinical situation while awaiting the return of C. diSficiZe toxin results. He or she is faced with the decision to continue supportive management or to perform a coionoscopy if there has been significant blood loss. This situation rarely occurs with adult patients.
to colonize the GI tract and to affect both the small and large bowel. It has been described as the most common agent causing pseudomembranous colitis, and recently, has been considered to be the only cause of true pseudomembranous colitis. C. di~ci~e, however, at most accounts for only 25% of antibioticassociated diarrhea ( I ,7). The bacterium produces two toxins that are involved in the pathogenesis of this diarrhea. Toxin A, an enterotoxin that causes hemorrhage and fluid secretion in animal models, is believed to be the primary toxin responsible for producing clinical symptoms (3). The second toxin, toxin B, is a cytotoxin detected by its cytopathic effects in cell culture. To detect toxin A, an enzymelinked immunosorbant assay (EIA) specific for the toxin is commonly used. EIA provides inexpensive, sensitive and specific (71 to 99%, and 91 to lOO%, respectively), non-invasive means to identify toxin A in stool specimens (8,9). Most toxin A assays, however, were validated in clinical laboratories by comparing toxin A detection to the
In This Issue ~i~~~~iu~ dif~~~~~Infeetion in Children . . . . . . . . . . . . . . . . . . .49 A review of the special issues and concerns related to C. difficile disease in pediatric patients
Microbiology Director Salary Survey . . . . . . . . . . . . . . . . .54
Organism Characteristics
Where do you fit?
C. dijj%ile is an anaerobic, grampositive, endospore-forming rod known
Upcoming Meetings Announcements . . . . . . . . . * . . . .55
0 1999 Elsevier Science Inc.
0196-4399199 (see frontmatter)
l
49
previously accepted toxin B cell culture assay. This comp~ison assumes that toxin A and toxin B are produced equally in every C. d#kile infection, an assumption that is now being debated in pediatric settings. Toxin B detection through cytotoxin neutralization testing has a reported sensitivity of 67 to 99% and a specificity of 95 to 99% but it is more expensive, labor intense, and can require 48 h to compfete (IO). First described in animal studies, a toxin-receptor mechanism is believed to account for human C. difSicile disease. The receptor, neurokinin- 1, is required for C. difficile toxin A to induce human enteritis. Studies have demonstrated, however, that the enzymatic activity of both toxins A and B was the main determinant of cytotoxic potency and the difference in receptor binding contributed to a lesser degree (11,12). Issues Related to Infants and Children Pediatric and adult C. dificile infections share many similar features, however, there are specific differences in children that makes this disease entity more formidable and challengiiig for the pediatrician. The epidemiology of C. d@kile in children is frequently divided into two groups. In neonates (c 6 weeks) and infants less than two years of age, toxin-producing strains of C. di~ciie are found in the stool but the patients are asymptomatic thus representing a carrier state (13). Colonization of neonates with C. difficile occurs within a few days of birth, usually from environmental sources rather than from maternal transmission (14). Free toxins, both Aand B, have been detected in the feces of asymptomatic neonates and infants. In children greater than two years of age, the epidemiology is similar to that seen in adults. The prevalence of the C. dificile carrier state in healthy, asymptomatic outpatients when detect-
ed by culture is reported to be as high as 70% in infants less than 18 months of age, 3% in children, and 1 to 3% in adults. This high asymptomatic carrier rate in infants often makes it difficult to interpret the clinical significance of detecting the organism or even the presence of toxins A or B in this age group without significant clinical disease. Studies of toxin B production in children with C. d~~ciie colonization have revealed that 22 to 28% of infants six days to six months of age, carry toxinproducing strains, whereas after six months of age, approximately 50% of the colonizing strains produce toxin B (15). Another study found that in these asymptomatic patients, many different serotypes of C. di~ci~e colonize the infant intestine and that 62.5% of the C. disficile isolates secrete neither toxin A or B, 37.5% secrete both toxins, and 3% secrete toxin A alone (16). Toxin B detection, however, has been reported to be more frequent in infants with diarrhea than in children over one year of age with diarrhea. Colonization with C. di~ciZe is signi~cantly lower in infants less than one year of age treated with antibiotics than children over one year of age. In addition to other seasonal infectious processes, we suspect C. dificile infection in children whenever there has been significant symptomatic diarrhea: an ill-appearing patient with severe dehydration and/or bloody stools with mucus. C. di$Jicile may be thought of classically as a nosocomial infection, but the endospores are ubiquitous making places where children congregate outside of hospitals, such as daycare centers, likely locations to acquire this infection (17). We would evaluate significant, symptomatic diarrhea for inpatients and outpatients similarly, but would be more sensitive to the circumstances in which C. difficile is more likely to occur. In our practice, this
applies to children younger than two years ~though not every child younger than six months may receive treatment for C. difsicile. If all other age-group appropriate etiologies for diarrhea have been excluded, such as enteric bacterial pathogens, milk-soy protein intolerance, rotavirus, etc., and either the C. di#iciZe toxin assay is positive or the patient remains symptomatic, then we recommend reagent. It has been reported that infants fed breast milk are less likely to develop C. dificile infection. Fewer breast-fed infants are colonized by C. di#kile than are bottle-fed infants at six weeks of age (21 vs. 47%) and six months of age (19 vs. 39%) (15). A Nigerian study supported the protective benefit of breast milk when the authors reported that the frequency of toxin B positivity in children fed formula alone was SO%, 19% in those taking both breast milk and formula, and 17.5% in those taking only breast milk ( 18). Immunoglobulin A or other non-immunoglobulin components secreted in breast milk are thought to inhibit C. di~cile toxin-A binding and may explain why breastfeeding is protective against disease and reduces toxin detection. This breast milk factor, however, does not prevent the cytotoxic activity of toxin B (19). Although adherence of the C. di$kiZe toxins to receptors is believed to be an irnpo~~t virulence factor in adult diarrhea, it may not be important in pediatric diarrhea since infants less than six months of age do not express toxin receptors on their enterocytes (20). A recent study of nosocomial diarrhea demonstrated that C. d@cile accounted for 3% of all in-patient pediatric diarrhea. In that study, C. difficile was, however, the most common pathogen identi~ed and occurred in 17.5% (7 of the 40 inpatients) in whom a pathogen was identified (21). Other studies have reported a 14.8% incidence of toxin B in C. dificile-
NOTE: No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. No suggested test or procedure should be carried out unless, in the reader’s judgment, its risk is justified. Because of rapid advances in the medical sciences, we recommend that the independent verification of diagnoses and drug doses should be made. Discussions, views and recommendations as to medical procedures, choice of drugs and drug dosages are the responsibility of the authors. Chid Micro&log? Newslener (ISSN 01964399) is issued twice monthly in one indexed volume per year by Elsevier Science Inc., 655 Avenue of the Americas, New York, NY 10010. Subscription price per year: for customers in Europe, The CIS, and Japan: NLG 423.00: for customers in all other countries: US$Z43.00. Periodical postage paid at New York, NY and at additional mailing offices. Postmaster: Send address changes to Cfinicd Microbiology NewsZe#e~ Elsevier Science Inc., 655 Avenue of the Americas, New York, NY KXJIO.For customer service, phone (212) 633-395O;TGLL-FREE for customers in the United States and Canada: I-888-4ES-INFO (1888-437-4636) or fax: (212) 633-3860.
50
0196-4399199 (see frontmatter)
0 IQ99 Else&r Science Inc.
Clinical Microbiology Newsletter 21:7,1999
related nosocomial diarrhea, and as high as 5 1 and 61% for non-antibioticand antibiotic-related diarrhea, respectively, in one study from Thailand (18,22). The incidence of C. difSicile nosocomial infections reportedly does not differ between adult and pediatric institutions.
Special Pop~ations Studies have shown that adults receiving chemotherapy for cancer are at increased risk of acquiring C. di$Gcileassociated diarrhea, even in the absence of antibiotics. It is believed that antineoplastic chemotherapy alters normal bowel flora in adults and causes extensive disruption of the intestinal mucosa, providing an excellent environment for C. dificile colonization and disease (23). For reasons not yet understood, this does not appear to be true in pediatric oncology patients receiving chemotherapy. Except in the case of a hospital outbreak, C. difSicile is not a pathogen in pediatric oncology patients (24). It is important that diarrhea not be accepted as a normal symptom of cancer chemotherapy in pediatric patients and that stool specimens be appropriately tested for all bacterial, viral, and parasitic etiologies. Because they continually receive antibiotics and are frequently hospitalized, children with cystic fibrosis (CF) would appear to be prime candidates for C. dificile diarrhea. Despite the risk factors, prospective studies have shown that disease with C. diJjTcileis unusual in children with CF (25,26). While as many as 22% of children with CF are colonized with toxigenic strains of C. di~cile and cytotoxin can be detected in the stool of most colonized patients, most CF patients have no GI symptoms. While reasons for this observation are still unproven, it is interesting to note that the normal GI flora in stool cultures from children with CF is much more likely to include organisms that are known to have inhibitory effects on C. di~c~le such as Pseudomo~~, Stap~~Lococcus, Lactobacillus, and Enterococcus species. This flora does not, however, explain why detectable cytotoxin in the stool of CF patients fails to cause symptoms.
Clinical and Laboratory Diagnosis When examined endoscopically for evidence of C. d@cile infection, adult patients show classic lesions at multiple Clinical Microbiology Newsletter 2h7.1999
sites on the mucosal surface. As a result, adults rarely require biopsy for histologic diagnosis of this pathogen. In children, however, there is a wide variety of possible endoscopic changes ranging from nodal-appe~ing mucosa to dramatic, characteristic mucosal findings. Lesions may be localized to or spare the rectum and result in segmental colitis or even pancolitis. Visible lesions, when present, may consist of patchy or diffuse erythema or may show the classical pseudomembranes that adhere to the colonic mucosa. They can range in size from 2 to 10 mm and are raised, yellowish, or grayish-white plaques surrounded by edema and erythema. The histological feature of C, difficile infection in children is a focal explosive mucosal lesion revealing a mushroom-like mass of cellular debris, that is referred to as a “volcano lesion.” These lesions exude fibrinous material, mucus, and neutrophils, which stream out of the underlying damaged crypts (13). Due to the endoscopic variability seen in pediatric C. dz#Gziledisease, biopsy is frequently required to make the diagnosis of PMC. It is not unusual for patients with normalappearing mucosa to have microscopic foci of disease below the surface in the lamina propria. Fortunately, the diagnosis of C. difltile is made easily by the detection of toxin A and/or toxin B produced by this organism. Cultures were once thought to be the most sensitive method whereas detection of toxin B by cell culture assay was felt to be most specific (27). Toxin A is an enterotoxin that causes mucosal inflammation, mucus discharge, increased vascular permeability, fluid secretion, epithelial necrosis, abdominal cramping, and gut motility abnormalities. Toxin A has been reported to be the primary mediator of illness (28). Toxin B is a cytotoxin that is ten-fold more potent than toxin A in causing mucosal damage (29). It is associated with diarrhea, hemorrhagic colitis, and cytopathic effects. To insure optimal detection, an adequate specimen must be obtained and properly handled. While the organism itself is hardy and resistant to desiccation, the toxins are less hardy and can deteriorate at room temperature. The stool must be liquid (formed stools are not acceptable), kept refrigerated between 2 to 8°C and transported to the laboratory on ice or frozen. These trans0 1999 Elsevier ScienceInc.
port requirements may pose significant problems for laboratories or physicians’ offices that refer stool specimens to other institutions or commercial laboratories for toxin detection. The relative importance of each toxin in pediatric diarrhea has not been fully established. It has been suggested by studies performed in adults that C. difJiciZetypically produces either both toxins concurrently or neither toxin (28). By C. di~cile culture, several studies have demonstrated that certain strains produce varying amounts of toxin A or B or none at all (30). Many hospital laboratories do not perform assays for both toxins on submitted stool specimens. Consequently, it is important to determine which C. dzfficile toxin(s) are prevalent and responsible for pathogenesis to best determine which toxin(s) should be detected. The primary C. dificile toxin related to disease in children remains controversial. The American Academy of Pediatrics (AAP): I997 Red Book: Report of the Committee on Infectious Diseases addresses this issue in its recommendation to test for C. dificile toxin B alone or for both toxins A and B (1). Failure to identify C. difJicile in the early stages of infection may result in substantial worsening of the disease since pediatricians may treat the diarrhea with antibiotics or antisecretory agents. Furthermore, the subsequent evaluation for patients with negative bacterial cultures and C. diflcile toxin-negative chronic diarrhea frequently includes radiologic and endoscopic studies. Failure to diagnose C. dificile in these patients may result in substantially increased and unnecessary costs. These additional studies also result in increased patient risk and discomfort. The implications of a study recently completed at our hospital are that neither the toxin A nor toxin B assay alone identifies all pediatric patients with C. disficile infection (3 1). Testing for only toxin A would have detected C. di~cile 50% of the time while testing for toxin B alone would have detected 82% of the infections (Table 1). There was no statistical significance found between toxin A and B detection in children younger than one year, however, there was statistical significance in ages 1 to 16 years and those >16 years (p=O.OOOl) (3 1). The data from our study supports the American Academy of Pediatrics 0196~3~~
(see frontmatter)
51
recommendations to test for C. dz$IciZe toxin B at a minimum. We would encourage those testing stools from children for toxin A alone to consider testing for toxin B, especially if the toxin A test is negative. The cost effectiveness of an improved diagnostic algorithm must be considered if patient care is to be optimized. A laboratory decision to identify only toxin A on specimens from children may be inappropriate. Results should be accompanied by a statement stating that a significant percentage of C. difSicile infections will be undetected by a single toxin assay. Given such a disclaimer, to address the problem of under-diagnosis, physicians might routinely order assays for both toxin A and B or order the second toxin if the first test is negative. Further studies are needed to determine if both toxins cause disease in the pediatric population and what laboratory testing approach might be most efficient and cost effective. We support the detection of both toxins in children to best diagnose this infection in a non-invasive manner. Since some health maintenance organizations may only approve reimbursement for toxin A detection, physicians who order C. diflicile toxin assays should understand the limitations of each assay available in their region. Previously, C. difficile detection by culture, even in the absence of cytotoxin detection in certain diarrhea1 syndromes, was considered evidence to treat (32). The role of culture is still controversial as one study showed that pseudomembranous colitis detected by endoscopy was associated with 5 1% of culture and toxin B assay positive stool, while 11%
of patients were culture positive but toxin B negative (27). Both groups responded similarly to metronidazole or vancomycin therapy. Toxin A was not evaluated in this study. C. dz~c~le culture is still important in laboratory research and epidemiology to identify the different strains and their virulence patterns
Antibiotic Treatment and Other Therapies Initial treatment of C. dz@Ale disease involves discontinuing the antibiotic therapy that initiated the disease and restoring lost fluids and electrolytes. For approximately 25% of patients, these measures will be sufficient. If symptoms do not resolve, or if the patient is debilitated or severely ill, then specific antibiotic therapy is used. Therapy for C. d~~ciZe primarily involves the use of metronidazole or vancomycin which are bactericide for this organism. C. d@tile is highly susceptible to vancomycin and usually, but not always, susceptible to metronidazole. V~comycin, however, is substantially (50 times) more expensive than metronidazole (33). Both medications are administered orally for 10 to 21 d and both have similar efficacy and relapse rates (34). Side effects of gastrointestinal discomfort, finger numbness and tingling, nephrotoxicity, and a metallic taste are more common with the use of metronidazole since it is systemically absorbed. Vancomycin is not systemically absorbed so it acts directly on the organism in the lumen of the intestine. Multiple relapses are an unfortunate sequel following treatment of C. d@icile pseudomembranous colitis and occurs with 10 to 20% of pediatric cases. Patients who relapse usually respond to
re-treatment with vancomycin but there are reports of children who have relapsed after multiple courses of both vancomytin and metronidazole. Relapses manifest as chronic diarrhea or repeated pseudomembranous colitis. During both forms of relapse, C. di@ciZe toxins reappear in the stool. Therapies other than antibiotics have been used in refractory or recurrent C. dijjicile infections. These treatments are directed at over-populating the gastrointestinal tract with nonpathogenic intestinal organisms, at reducing the number of C. di~cile org~isms, or at binding the toxins. Anion-exchange resins, such as cholestyramine, directly bind to the toxins of C. di~ciZe and are a treatment option in mild or moderate disease but are not as effective as antibiotics in cases of severe disease. The major drawback with use of these resins is that they also bind to vancomycin and cannot be used in combination with this antibiotic. Several studies have attempted to prevent recurrent C. difficile disease by oral administration or by enema introduction of nonpathogenic organisms into the gastrointestinal tract to compete with the C. difficile. Preparations of lactobacilli or the nonpathogenic yeast Saccharomyces boulardii are the most popular. Both are given in capsule form, can be taken safely, and only transiently colonize the GI tract. Because S. boulurdii is unaffected by antibiotics, an ad~tional advantage is that it can be given in combination with antibiotic therapy. The use of S. boulardii and Lactobacillus GG in symptomatic infants who were toxin positive resulted in significant improve-
ment and prevention of relapse (33-36).
Conclusion Table 1. Frequency of detection of C. diJt?cile toxins by patient age”
No.
Positive for
Positive for
Positive for
Samnles
toxin A onlv
toxin B only
toxins A and B
<6 months old
28
8 (28.6%)
5 (17.8%)
15 (53.6%)
6 months to ~1 year
32
9 (28.1%)
17 (53.1%)
6 (18.8%)
1 year old to ~16 years
182
29 (15.9%)
92 (50.5%)
61 (33.5%)
216 years
34
5 (14.7%)
19 (55.9%)
10 (29.4%)
All ages
276
51 (18.5%)
133 (48.2%)
92 (33.3%)
Age Grouvs
“Data from reference 31
52
01964399/99 (see frontmatter)
0 1999 Elsevier Science Inc.
C. diflcile is more problematic in children than adults because of problems in maintaining hydration and issues related to rapid weight loss due to diarrhea. Unlike adults who have reserve energy and nutrient stores, in infants and young children, these can rapidly become depleted from C. di~cile diar-
rhea. Controversy exists about the pathogenicity of this organism in the infant population due to their high colonization rate yet anecdotally, treatment of these infants results in resolution of symptoms. Further studies in this population group are warranted. In pediatric C. di$cile disease, both toxins have
Chical Microbiology Newsletter 21:7,1999
been implicated in disease and vary in rate of detection. The assumption that both toxins are produced equally in all symptomatic C. diflcile infections recently has been challenged. Until further studies substantiate or disprove these findings and a cost-effective algorithm is determined, tests to detect both toxin A and toxin B should be routinely performed when C. diflcile is a suspected cause of pediatric diarrhea. References 1. Peter, G. (ed.). 1997. Clostridium dzficile, p. 177-178. in: Ame~can Academy of
Pediatrics Red Book: Report of the Committee on Infectious Diseases. 24th ed. American Academy of Pediatrics, Elk Grove Village, IL. 2. Qualman, S.J. et al. 1990. Clostrid~~ dificile invasion and toxin circulation in fatal pediatric pseudomembr~ous colitis. Am. J. Clin. Pathol. 94:410-416.
Clostridium, p. 580-581. In Murray P.R. et al. (eds,). Manual of Clinical Microbiology. 6th ed. ASM Press, Washington, DC.
11. Castagliuolo, I. et al. 1998. Neurokinin1 (NK-1) receptor is required in Clostridium d~~cile-induct enteritis. J. Clin. Invest. 101:1547-1550. 12. Chaves-Olarte, E. et al. 1997. Toxins A and B from Clost~dium dijkile differ with respect to enzymatic potencies, cellular substrate specificities, and surface binding to cultured cells. J. Clin. Invest. 100:1734-1741. 13. Mitty, R.D. andT. LaMont. 1996. Pseudomembranous colitis. p. 726-739. In: Walker, W.A. et al. (eds). Pediatric Gastroenterointestinal Disease: Pathophysiology, Diagnosis, Management. 2nd ed., Vol. 1. Mosby, Philadelphia. 14. Larson, H.E. et al. 1984. Epidemiology of Clostridi~ dijjkile in infants. J. Infect. Dis. 146:727-733.
3. Lyerly, D.M., H.C. Krivan, andT.D. Wilkins. 1988. Clostridi~ dificile: its disease and toxins. Clin. Microbial. Rev. 1:1-l%
15. Tullus, K. et al. 1989. Intestinal colonization with Clostridium difficile in infants up to 18 months of age. Eur. J. Clin. Microbial. and Infect. Dis. 8:390-393.
4. Thomas, D.F.M. et al. 1986. Enterocolitis in Hirshsprung’s disease: a controlled study of the etiologic role of Clostridium digicile. J. Pediatr. Surg. 21:22-25.
16. Collignon, A. et al. 1993. Heterogenicity of Clost~dium d@cile isolates from infants. Eur. J. Ped. 152:319-322.
5. Thomas, D.F.M. et al. 1982. Association between Clostridium d@cile and enterocolitis in Hirschsprung’s disease. Lancet i:78-79. 6. Hardy, .%I?,R. Bayston, and L. Spitz. 1993. Prolonged carriage of Clostridium difsicile in Hi~chsp~ng’s disease. Arch. Dis. Child. 69:221-224. 7. Whitehead, R. 1995. Primary inflammatory disorders and disturbances of digestive function. p. 614-616. In: Whitehead, R. (ed.) Gastrointestin~ and Esophageal Pathology, 2nd ed. Churchill Livingstone, New York. 8. Whittier, S. et al. 1994. Evaluation of four commercially available enzyme immunoassays for laboratory diagnosis of Clastridium difJicile-associated diseases. J. Clin. M~crobiol. 31:2861-2865. 9. Doem, G.V., R.T. Coughlin, and L. Wu. 1992. Laboratory diagnosis of Clostridium d@cile-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. J. Clin. Microbial. 30:2042-2046. 10. Onderdonk, A.B. and S.D. Allen. 1995.
Clinical Microbiology Newsletter 21:7,1999
17. Kim, K. et al. 1983. Outbreaks of diarrhea associated with Clostridium dificile and its toxin in day-care centers: evidence for peon-to-arson spread. J. Peds. 102:376-382. 18. Emeruwa,A.C. and J.U. Oguike. 1990. Incidence of cytotoxin producing isolates of Clostridium dificile in faeces of neonates and children in Nigeria. Microbiologica 13:323-328. 19. Rolfe, R.D. and W. Song. 1995. Immunoglobulin and non-immunoglobulin components of human milk inhibit Clostridium d@cile toxin A-receptor binding. J. Med. Microbial. 42:10-19. 20. Gonzalez-Valencia, G., 0. Munoz, and J.F. Torres. 1991. Toxigenicity and adherence in Clostridium d@cile strains isolated from patients with and without diarrhoea. Arch Invest. Med. 22: 189196. 21. Meropol, S.B., A.A. Luberti, and A.R. DeJong. 1997. Yield from stool testing of pediatric inpatients. Arch. Pediatr. Adolesc. Med. 151:142-145. 22. Won~a~ch, S. et al. 1990. Clostridi~ dificile associated disease in Thailand. SE Asian J. Trop. Med. and Pub. Health. 21:367-372. 23. Anand, A. and A.E. Glatt. 1993. Clostridium dz$kile infection associated
0 1999 Ekevier Science Inc.
with antineoplastic chemotherapy: a review. Clin. Infect. Dis. 17: 109-l 13. 24. Burgner, S.S. et al. 1997. A prospective study of Clostridium dificile infection and colonization in pediatric oncology patients. Pediatr. Infect. Dis. J. 16: 113l1134. 25. Welkon, C.J. et al. 1985. Clostridium dificile in patients with cystic fibrosis. AJDC 139:805-808. 26. Wu, T.C., V.P. McCarthy, and V.J. Gill. 1983. Isolate rate and toxigenic potential of Clostridium d@kile isolates from patients with cystic fibrosis. J. Infect. Dis. 148:176. 27. Gerding, D.N. and J.S. Brazier. 1993. Optimal methods for identifying Clostridium dificile infections. Clin. Infect. Dis. 16 Suppl4:S439-S442. 28. Fekety, R. 1995. Antibiotic-associated colitis. p. 978-987. In: Mandell, G. L. et al. (eds). Principles and Practice of Infectious Fisease. 4th ed. Churchill Livingstone, New York. 29. Riegler, M. et al, 1993. Clostridium dificile toxin B is more potent than toxin A in damaging human colonic mucosa in vitro. Gastroenterology 104:A770. 30. Bare, MC. et al. 1992. Effects of antibiotics and other drugs on toxin production in Clostridium d$tkile in vitro and in vivo. Antimicrob. Agents Chemother. 36:1332-1335. 31. Kader, H.A. et al. 1998. Detection of Clostridium dificile toxins A or B alone will not diagnose all Clostridium dificile diarrhea in pediatric patients, Gastroenterology 115:1-7. 32. Lashner, B.A. et al. 1986. Clostridium disficile culture-positive toxin-negative diarrhea. Am. J. Gastroenterol. 81:940943. 33. Fekety,R. andA.B. Shah. 1993. Diagnosis and treatment of recurrent Clostridium dif&ile colitis. JAMA 269:71-75. 34. Talbot, R.W., R.C. Walker, and R.W. Beart Jr. 1986. Changing epidemiology, diagnosis, and treatment of Clostridium d~~cile toxin-associated colitis. Brit. J. Surg. 73:457-460. 35. Buts, J.P., G. Corthier, and M. Delmee. 1993. Succharomyces boulardii for Clostridium di$icile-associated enteropathies in infants. J. Ped. Gastroenterol. and Nutr. 16:419-425. 36. Gorbach, S.L., T.W. Chang, and B. Goldin. 1987. Successful treatment of relapsing Clostridium dificile colitis with ~ctobacillus GG. Lancet 2: 15 19.
0196-4399199 (see frontmatter)
53