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Clostridium difficile: Shifting Sands of a Pesky Pathogen

Clostridium difficile: Shifting Sands of a Pesky Pathogen. Bob Fader, Ph.D. D (ABMM) Section Chief, Microbiology Scott & White Memorial Hospital Temple, TX rfader@swmail.sw.org. Objectives. Identify the reasons for the increase and severity of Clostridium difficile diarrhea

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Clostridium difficile: Shifting Sands of a Pesky Pathogen

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  1. Clostridium difficile: Shifting Sands of a Pesky Pathogen Bob Fader, Ph.D. D (ABMM) Section Chief, Microbiology Scott & White Memorial Hospital Temple, TX rfader@swmail.sw.org

  2. Objectives • Identify the reasons for the increase and severity of Clostridium difficile diarrhea • List the methods of lab testing for C. difficile and discuss the pros and cons of each method • Describe treatment modalities for C. difficile disease • Discuss Infection Control processes required for containment of C. difficile in the health care setting

  3. Clostridium difficile – The Basics • Anaerobic Gram positive bacillus • Spore-former • Normal bowel flora in 2 - 5% of population • Up to 20% in LTC facilities • Infection most often associated with prior antibiotic therapy • Originally strictly a hospital-acquired infection but now can also be seen in outpatients as well

  4. C. difficile – Advanced Info • C. difficile diarrhea is a toxin-mediated disease • Large increase in number and severity of cases seen since 2004 • Largely due to strain with deletion in regulatory gene for toxin production • Results in 20-fold increase in toxin production • Increasing number of strains also resistant to the fluoroquinolones

  5. APIC C. difficile SurveyNational Prevalence Study of Clostridium difficile in U.S. Healthcare Facilities • Health care institutions requested to collect data on C. difficile on any one day (May-August 2008) • 648 facilities • 13 of every 1000 pts either infected or colonized • 6.5 - 20 times higher than previous estimates

  6. So what happened? • Appearance of a new strain of C. difficile in hospitals in Quebec • Quickly spread south to the U.S. and over to Europe • Strain is known as NAP1 (toxinotype III)

  7. Spread of NAP1 strain of C. difficile

  8. Deaths in the UK caused by C. difficile

  9. C. difficile Epidemiology Normal colon Pseudo membranous colitis

  10. C. difficile Toxin Genes

  11. Increased Toxin A Production invitro In vitro production of toxins A and B by C. difficile isolates. Median concentration and IQRs are shown. C. difficile strains included 25 toxinotype 0 and 15 NAP1/027 strains (toxinotype III) from various locations. From Warny M, et al. Lancet. 2005;366:1079-1084.

  12. Increased Toxin B Production invitro In vitro production of toxins A and B by C. difficile isolates. Median concentration and IQRs are shown. C. difficile strains included 25 toxinotype 0 and 15 NAP1/027 strains (toxinotype III) from various locations. From Warny M, et al. Lancet. 2005;366:1079-1084.

  13. Comparison of Molecular Characteristics of 2 C. difficile Isolates with Historical Standard-Type Strains and a Recently Recognized Epidemic Strain, by Selected Characteristics, OH and PA, 2005 *Pulsed-field gel electrophoresis. † North American pulsed-field type 1. McDonald LC, Killgore GE, Thompson A, Owens RC Jr, Kazakova SV, Sambol SP, Johnson S, Gerding DN. An epidemic, toxin gene-variant strain of Clostridium difficile. N Engl J Med. 2005;353:2433-2441. CDC. MMWR. 2005;54:1201-1205.

  14. Resistance of Current (after 2000) BI/NAP1 Isolates to Clindamycin and Fluoroquinolones Compared with Current Non-BI/NAP1 Isolates and Historic (before 2001) BI/NAP1 Isolates From McDonald LC, et al. N Engl J Med. 2005;353:2433-2441.

  15. C.difficile-associated diseases (CDAD) • Antibiotic-associated diarrhea • Pseudomembranous colitis • Toxic megacolon • Perforations of the colon • Sepsis • Death (rarely)

  16. C. difficile Clinical Symptoms • Watery diarrhea • Fever • Loss of appetite • Nausea • Abdominal pain/tenderness

  17. Risk factors for C. difficile • Prior antibiotic exposure • GI surgery/endoscopy • Long LOS in health care setting • Serious underlying illness • Immunocompromising conditions • Advanced age • Proton pump inhibitors?

  18. Changes in age-specific C. difficile associated disease 2000-2005 Zilberberg, M.D. et al. Increase in Adult Clostridium difficile-related hospitalizations and case-fatality rate, United States, 2000-2005. Emerg Infect Dis 2008 Vol 14 No 6

  19. Stomach Acid-Suppressing Medications and Community-Acquired CDAD, England From Dial S, et al. JAMA. 2005;294:2989-2995.

  20. Severe CDAD in Populations Previously at Low Risk—Four States, 2005 • Recent reports to the Pennsylvania Department of Health and CDC • Young patients without serious underlying disease • C.difficile toxin-positive by routine diagnostic testing • Responded to CDAD-specific therapy • Peripartum • Within 4 weeks of delivery • Reports from PA, NJ, OH, and NH • Community-associated • No hospital exposure in prior 3 months • Reports from Philadelphia and 4 surrounding counties CDC. MMWR. 2005;54:1201-1205.

  21. Severe CDAD in Populations Previously at Low Risk—Four States, 2005 (2) CDC. MMWR. 2005;54:1201-1205.

  22. Severe CDAD in Populations Previously at Low Risk—Four States, 2005 • Transmission to close contacts in 4 cases • 8 cases without antimicrobial exposure • 5 children; 3 required hospitalization • 3 had close contact with diarrheal illness • Another 3 cases with < 3 doses of antimicrobials • Clindamycin most common exposure (10 cases) • Estimated minimum annual incidence of community-associated disease • 7.6 cases per 100,000 population • 1 case per 5,000 outpatient antimicrobial prescriptions CDC. MMWR. 2005;54:1201-1205.

  23. Laboratory Diagnosis of C. difficile“A disease in search of a good diagnostic test”

  24. C. difficile - Lab TestingGeneral Caveats • Lab testing should only be performed on diarrheal stools (conform to the shape of the container) • One or two specimens collected on consecutive days are sufficient for diagnosis • No more than one specimen per day • Swab specimens are insufficient • Once pt positive, no further testing for at least 2 weeks **No “Test of Cure”**

  25. C. difficile - Lab testing Options • Culture on CCFA agar (Cycloserine Cefoxitin Fructose agar) • Most sensitive and specific • If isolated still need to confirm toxin production • 72-96 hour turn-around-time • Requires anaerobic culture

  26. C. difficile – Lab Testing continued • Latex agglutination – • originally marketed as toxin assay • now known to detect glutamate dehydrogenase enzyme • present in C. difficile but also in other organisms (C. sordellii) • Same day or next day results • Need to confirm positives with toxin assay

  27. C. difficile – Lab Testing continued • Enzyme immunoassays • Detection of Toxin A only • Will not detect ToxA negative/ToxB positive strains • Detection of Toxins A&B • Better sensitivity than toxin A alone • Microwell, lateral flow assay formats • Same day or next day results • Most popular (>90% of labs) • Sensitivities – 65-85%

  28. Microwell enzyme immunoassay Lateral flow EIA

  29. C. difficile – Lab Testing continued • Cell culture Cytotoxicity Assay – • Detects Toxin B (Cytotoxin) only • Will not detect ToxA positive/ToxB negative strains • Considered the “gold standard” for toxin testing • Requires tissue culture capability • Costly, slow, and time consuming • 24-48 hour turn-around-time

  30. C. difficile – Lab Testing continued • Rapid enzyme EIA for glutamate dehydrogenase enzyme • Used as initial screen • If negative you can report out as negative • Positive rapid test requires confirmation by cell culture cytotoxicity assay, EIA or PCR • High specificity for negatives but still cannot provide a rapid result for a positive patient

  31. C. difficile – Lab Testing continued • Polymerase chain reaction • BD GeneOhm Cdiff PCR assay has recently been FDA approved • Targets the Toxin B gene • Fresh stool: Sensitivity 93.8%/Specificity 95.5% • Frozen stool: Sensitivity 100%/Specificity 97.7% • Evidence suggests a single negative is enough to rule out infection

  32. C. difficile – Lab Testing continued • Polymerase chain reaction for toxin A and toxin B (S&W) • Primers and probes for Toxin A and B • 146 specimens • PCR picked up 7 additional positives (37 vs 44) Smith, D, Hocker, K, Fader, B, Luna, RA, Versalovic, J, Rao, A. Rapid PCR screening strategy for hospital acquired infections including vancomycin-resistant Enterococci and Clostridium difficile in adult patients. (ASM Annual meeting, 2008)

  33. C. difficile Treatment • Discontinue current antibiotics • 23% cure rate • Antibiotics – metronidazole • oral vancomycin • concern about selection of VRE • 20% relapse rate • Continue with metronidazole • 2nd relapse – switch to vancomycin

  34. C. difficile Treatment continued • “Severe disease” • Zar and CDC criteria • Vancomycin shown superior to metronidazole • Toxic megacolon – direct installation of vancomycin + IV metronidazole

  35. C. difficile Treatment continued • Other antibiotics? (rifamixin, nitazoxinide) • Toxin binding compound was in development • Recently stopped study • Monoclonal antibodies • Vaccine in development • Probiotics – Saccharomyces boulardii and Lactobacilli - questionable results • usually in combination with antibiotics

  36. Treatment – Stool Transplant • Reserved for severe pseudomembranous colitis and toxic megacolon • Stool donated by healthy volunteer – usually family member • Fresh stool is homogenized, filtered through coffee filter X2 • Administered by nasogastric tube or by enema • Usually 5 treatments to help restore normal flora Recurrent Clostridium difficile Colitis: Case Series Involving 18 Patients Treated with Donor Stool Administered via a Nasogastric Tube. Johannes Aas, Charles E. Gessert, and Johan S. Bakken; Clin. Infect. Dis. 2003. 36:580-585

  37. Infection Control Recommendations • Conduct surveillance. Track positive numbers and outcomes • Emphasize early diagnosis and treatment to physicians • Enforce strict Infection Control policies • Contact precautions • Hand washing with soap and water as opposed to alcohol-based hand rinse when caring for C. diff positive pts

  38. Infection Control Recommendations • Environmental cleaning and disinfection strategy (need sporicidal agent) • Terminal cleaning - Routine cleaning (Sani-Master 4) vs (Dispatch) • SaniMaster 4 – ammonium chloride • Dispatch – sodium hypochlorite • Sani-wipes for equipment and other items • Glo-Germ® to evaluate cleaning

  39. Surveillance - Should we Screen? • Is C. difficile the next organism for active surveillance on inpatient admission? • If so, should you also screen for Vancomycin- Resistant Enterococcus (VRE) with the same specimen? • If nothing else, all positive C. difficile tests from the laboratory should be reported to Infection Control for tracking

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