Objective: To assess the availability of the laboratory diagnosis of infections caused by C. difficile in the Czech Republic (CR), including the range of tests used, possible combinations, and adequate interpretation of model results.
Material and methods: Data were collected through a web questionnaire survey with the participation of representatives of 61 public and private microbiological laboratories. The questionnaire addressed the use of diagnostic test kits and culture media in the diagnosis of C. difficile infection (CDI). In addition, the respondents were asked to interpret a glutamate dehydrogenase (GDH) positive and, at the same time, toxin A/B negative result, without or with laboratory confirmation if available.
Results: In the CR, the most commonly used test in the diagnosis of CDI is the C. DIFF Quik Chek Complete® test (Alere) for the detection of GDH and A/B toxins, as reported by 50 (82%) laboratories. Anaerobic culture is performed by 43 (70.5%) laboratories, 21 (48.8%) of which use selective agar (Oxoid). Direct detection of DNA of toxigenic C. difficile is feasible in 17 (27.9%) laboratories, with most of them (15 laboratories) using the closed system Xpert® C. difficile (Cepheid). The diagnosis based only on the detection of GDH and A/B toxins is used by 13 (21.3%) laboratories. Two (3.3%) laboratories detect A/B toxins alone and three (4.9%) laboratories carry out the detection of A/B toxins followed by anaerobic culture. A three step scheme: detection of GDH and A/B toxins with subsequent anaerobic culture is used by 26 (42.6%) laboratories. The detection of GDH and A/B toxins along with a PCR assay are provided by three (4.9%) laboratories. A complete diagnostic scheme for CDI (detection of GDH and A/B toxins, direct detection of DNA, and aerobic culture) is feasible in 14 (23%) laboratories.
Conclusion: This questionnaire survey study identified 24 different testing algorithms to be in use within the study period (April to July 2014) in the CR. Five (8.2%) laboratories have no highly sensitive screening test such as the detection of GDH or nucleic acid amplification test (NAAT) included in their testing algorithm. Thirteen (21.3%) laboratories perform the detection of GDH and A/B toxins but have no confirmation method to be used if only one test turns out positive. In the case of GDH positivity and A/B toxin negativity, the result should be provided with a supplementary comment on further possibilities for the laboratory detection of CDI and the claimed sensitivity of the test used. If no confirmation test is available, the result should be considered as epidemiologically and clinically significant, once other possible causes of diarrhoea are ruled out.
Keywords: Clostridium difficile - diagnosis - testing algorithm - glutamate dehydrogenase - A/B toxins..