Identification of bacterial strains by laboratories participating in the Deutsches Krebsforschungszentrum quality assurance programme

Abstract

The quality assurance programme (QAP) of the Deutsches Krebsforschungszentrum (DKFZ) is a proficiency testing system developed to service the laboratory animal discipline. QAP comprises the quarterly distribution of two bacterial strains originating from various species of animals for identification to the species level and antibiotic susceptibility testing. We compared identification results reported by QAP participants over the years 1996-2004 with those obtained by the Dutch Bacterial Diagnostics reference laboratory on 68 samples comprising 71 bacterial strains and a fungus. Significant differences were found in the frequency of reported and correct identifications when bacteria were assigned to different groups based on morphology by Gram stain and on origin (animal versus environmental, rodent and rabbit versus other animal species, pathogen versus non-pathogens). Rodent and rabbit pathogens yielded 73% correct identifications, and with all bacterial strains only 60% of the identifications were correct. We assume that most QAP participants were from laboratory animal diagnostic laboratories. If this is true, the capabilities of laboratories in the laboratory animal discipline to correctly identify bacterial species are well below what are considered acceptable limits for human diagnostic laboratories. The distribution of cultured bacteria circumvents the most difficult step in the microbiological monitoring of animals, namely primary culture from clinical samples. We propose to set up a QAP that comprises the distribution of specimens mimicking clinical samples normally submitted to laboratory animal diagnostic laboratories.

16S ribosomal DNA sequence-based identification of bacteria in laboratory rodents: a practical approach in laboratory animal bacteriology diagnostics

“…3 In these conditions the capabilities of laboratories in the laboratory animal discipline to correctly identify bacterial species are well below what are considered to be acceptable limits for human diagnostic laboratories. 4 Identification of bacteria by partial 16S ribosomal RNA (rRNA) gene sequencing is considered to be more accurate than the conventional phenotypic methods. 5,6 Bacterial 16S rRNA genes contain nine 'hypervariable regions' (V1-V9) that demonstrate considerable sequence diversity among different bacterial species and thus allow their differentiation.…”

Frequent major errors in antimicrobial susceptibility testing of bacterial strains distributed under the Deutsches Krebsforschungszentrum Quality Assurance Program

“…11 We reported earlier that laboratory animal diagnostic laboratories showed poor performance in proper species classification of bacterial strains. 1 The present evaluation indicates that the quality of AST by laboratory animal diagnostic laboratories participating in the DKFZ-QAP over the period 1996 -2004 was also far below standards considered acceptable in human diagnostic microbiology.…”

“…We found that the capabilities of laboratory animal diagnostic laboratories to correctly identify bacterial species was considerably below what is considered acceptable for human diagnostic laboratories. 1 The outcome of the AST over the same period is now reported.…”

ICLAS LAQ Network for the Promotion of Animal Quality in Research

“…However, the objective of these programs was to reach a diagnostic consensus rather than to provide already confirmed samples to serve as reference specimens for laboratories. 4 …”