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 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

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

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

APIC C. difficile Survey National 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

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)

Spread of NAP1 strain of C. difficile

Deaths in the UK caused by C. difficile

C. difficile Epidemiology Normal colon Pseudo membranous colitis

C. difficile Toxin Genes

Increased Toxin A Production in vitro 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. Approximately 16 fold increased toxin A production by the epidemic strain From Warny M, et al. Lancet. 2005;366:1079-1084.

Increased Toxin B Production in vitro 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. Approximately 23 fold increase in toxin B production From Warny M, et al. Lancet. 2005;366:1079-1084.

Comparison of Molecular Characteristics of 2 C 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 Characteristic Standard Strain Epidemic Strain Ohio Strain Pennsylvania Strain Toxinotype PFGE* pattern Binary toxin 18 bp deletion in tcdC < 80% related to NAP1† _ III NAP1 + IX 85% related to NAP1 XIV/XV 64% related to NAP1 *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.

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 No. (%) Intermediate or Resistant to: Current BI/NAP1 Isolates n=24 (%) non- P-Value for vs. Non- Historic n=14 (%) Current vs. Clindamycin 19 (79) 1.0 10 (71) 0.7 Levofloxacin 24 (100) 23 (96) 14 (100) Gatifloxacin 10 (42) <0.001 Moxifloxacin From McDonald LC, et al. N Engl J Med. 2005;353:2433-2441.

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

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

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?

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

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

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.

Severe CDAD in Populations Previously at Low Risk—Four States, 2005 (2) Characteristic, No. (%) Community (N=23) Peripartum (N=10) Total (N=33) Aged < 18 years 11 (48) 0 (0) 11 (33) Female 15 (65) 10 (100) 25 (76) Antimicrobial exposure 9 (90) 24 (73) Bloody diarrhea 6 (26) 2 (20) 8 (24) Hospitalization necessary 4 (40) 10 (24) ER visit necessary 3 (13) 5 (15) Relapse 8 (35) 5 (50) 13 (39) CDC. MMWR. 2005;54:1201-1205.

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.

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

C. difficile - Lab Testing General 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”**

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

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

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%

Microwell enzyme immunoassay Lateral flow EIA

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

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

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

C. difficile – Lab Testing continued EIA PCR Sens 84% 100% Spec 97.7% PPV 94.9% NPV 92.2% 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)

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

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

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

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

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

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

The rails are considered a “high touch” area in the patient environment.

We have reusable medical equipment that is usually shared between patients. I would have to make the assumption their stethoscope and bp cuff were not cleaned after the last patient.

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