Estimating risk of C. difficile transmission from PCR positive but cytotoxin negative cases Journal Article


Authors: Kamboj, M.; Esther Babady, N.; Marsh, J. W.; Schlackman, J. L.; Son, C.; Sun, J.; Eagan, J.; Tang, Y. W.; Sepkowitz, K.
Article Title: Estimating risk of C. difficile transmission from PCR positive but cytotoxin negative cases
Abstract: Background: The use of molecular methods to diagnose Clostridium difficile infection (CDI) has improved diagnostic yield compared to conventional methods. However, PCR testing can detect colonization and has introduced several practical challenges pertaining to need for treatment and isolation of cases. Methods: For all new cases detected by real-time PCR, concurrent cytotoxin assay was performed and genetic characterization with MLVA (multi-locus variable number tandem repeat analysis) was done to determine relatedness. We used PCR cycle threshold (Ct) of detection as surrogate marker for bacterial burden in stool. Results: Overall, 54 cases of CDI were detected during the study period. 42 were concurrently tested by CYT and characterized by MLVA. MLVA analysis revealed marked genetic diversity with no ongoing outbreaks; four cases were due to NAP1 strain. CYT-/PCR + cases had a higher median Ct value of detection compared to CYT+/PCR + cases (28.2 vs 22.5; p = 0.01). Among 25 strains that were genetically related, 9/11 isolates in this dominant cluster were positive by CYT compared to 4/14 in non-dominant clusters (p = 0.02). Conclusion: CYT-/PCR+ cases contribute to hospital based transmission. However, the risk of transmission of C. difficile from CYT +/PCR+ cases may be higher than those that are CYT-/PCR+. © 2014 Kamboj et al.
Keywords: child; clinical article; controlled study; gene cluster; genetic trait; nonhuman; genetic variability; genotype; bacterium detection; bacterium isolate; real time polymerase chain reaction; clostridium difficile infection; clostridium difficile; bacterial transmission; infection risk; feces analysis; cytotoxicity assay; cytotoxin; bacterial load; variable number of tandem repeat; human; male; female; article
Journal Title: PLoS ONE
Volume: 9
Issue: 2
ISSN: 1932-6203
Publisher: Public Library of Science  
Date Published: 2014-02-11
Start Page: e88262
Language: English
DOI: 10.1371/journal.pone.0088262
PROVIDER: scopus
PMCID: PMC3921148
PUBMED: 24523882
DOI/URL:
Notes: Export Date: 1 August 2014 -- CODEN: POLNC -- Source: Scopus
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MSK Authors
  1. Ngolela Esther Babady
    124 Babady
  2. Kent A Sepkowitz
    270 Sepkowitz
  3. Mini Kamboj
    116 Kamboj
  4. Crystal Son
    12 Son
  5. Janet A Eagan
    38 Eagan
  6. Yi-Wei Tang
    173 Tang
  7. Janet Yuan Sun
    8 Sun