Evaluation of rapid identification methods for foodborne diarrhea Campylobacter and detection of drug resistance / 中华检验医学杂志

ABSTRACT

Objective:To explore and evaluate a appropriate suitable method for detection of Campylobacter and antibiotic sensitivity test for foodborne diarrhea in clinical laboratories. Methods:Pre-experiment:a total number of 400 fecal samples of patients with foodborne diarrhea were prospectively collected from the intestinal disease clinic of Beijing Tongren Hospital from September 2017 to January 2018. Double-hole filtration culture method and modified cefoperazone charcoal deoxycholate (CCD) agar culture method were used for fecal culture in micro-aerobic environment for 48 hours, and then suspicious colonies were identified by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Meanwhile, C. jejuni and C. coli were detected by real-time quantitative polymerase chain reaction(qPCR). Large sample verification: 2 062 fecal samples of patients with foodborne diarrhea in three hospitals of different levels in different areas of Beijing were collected for qPCR detection and culture from April 2018 to March 2019. The antimicrobial sensitivity test (AST) of C. jejuni and C. coli was performed according to the disk diffusion method and agar dilution method recommended by Clinical and Laboratory Standards Institute and National Antimicrobial Resistance Monitoring System for Enteric Bacteria. The results of the three detection methods and the consistency of the two antibiotic sensitivity tests were compared. Results:In the pre-experiment, the positive rates of Campylobacter ( jejuni/coli) detected of qPCR, double-hole filtration culture and modified CCD agar culture were 9.0% (36/400), 5.0% (20/400)and 3.5% (14/400), and the difference was statistically significant ( P<0.01). The samples with negative result of qPCR were negative by both culture methods. The total positive rates of Campylobacter detected by qPCR was 8.1% (168/ 2 062)including 7.0% (144/2 062) for C. jejuni and 1.2% (24/2 062) for C. coli. The samples with positive qPCR results were cultured by double-hole filtration culture method and the positive rate was 61.9%(104/168), among which, the positive rate of C. jejuni and C. coli were 58.3%(84/144) and 83.3%(20/24) respectively, which was not significantly different from the detection rate and culture positive rate in the pre-test ( P>0.1). The resistance rates of C. jejuni and C. coli to ciprofloxacin were 94.0%(94/100) and 100.0%(24/24) and to erythromycin were 6.0%(6/100) and 33.3%(8/24). The results from two antibiotic sensitivity test methods were consistent (Kappa>0.75). Conclusions:qPCR is rapid, sensitive and easy to operate, so it is suitable for routine development in clinical laboratories. The double-hole filtration culture method is beneficial to the acquisition of strains and is essential for the further study of Campylobacter. There was no significant difference between agar dilution method and disk diffusion method in antibiotic sensitivity test. Campylobacter showed a very high resistance rate to quinolones, which was no longer suitable for the treatment of Campylobacter foodborne diarrhea in Beijing area. Macrocyclic lipid antibiotics should be preferred.