AUTHOR=Wu Xiufeng , Zhan Fuguo , Zhang Jiawei , Chen Shanjian , Yang Bin TITLE=Identification of hypervirulent Klebsiella pneumoniae carrying terW gene by MacConkey-potassium tellurite medium in the general population JOURNAL=Frontiers in Public Health VOLUME=Volume 10 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2022.946370 DOI=10.3389/fpubh.2022.946370 ISSN=2296-2565 ABSTRACT=Objectives: To establish a MacConkey-potassium tellurium medium-based method for selectively culturing terW gene-positive Klebsiella pneumoniae (KP), to evaluate its performance and apply it to identifying particular clonal hypervirulent KP (hvKP) strains in epidemiological surveillance. Methods: The virulence genes, rmpA, iutA and terW, were detected by PCR. The minimum inhibitory concentration of potassium tellurite of hvKP (rmpA+/ iutA+) and classical KP (rmpA- and iutA-) was determined by agar dilution method. The MacConkey medium containing 4 μg/ml potassium tellurite was prepared and the performance in detecting terW+ KP was evaluated, including agreement with PCR and positive/negative predictive value. Fecal samples from healthy volunteers in Fujian were collected and cultured in the medium, then positive strains were identified by MALDI-TOF MS, antimicrobial susceptibility were tested by Kirby-Bauer assays, and virulence genes and capsular serotype genes were tested by PCR. Results: In KP isolated from clinical specimens (N=198), the positive rate of terW was 37.9%, and the detection rate of terW in hvKP was significantly higher than that in classical KP (70.6% vs 13.3%). The potassium tellurite resistance levels of terW+ (N=75) and terW- (N=55) KP were 8 ~ 128 μg/ml and <1 μg/ml ~ 8 μg/ml, respectively, with significant differences. KP was selectively cultured on a MacConkey medium with 4 μg/ml potassium tellurite, and its agreement with PCR was good (Kappa=0.936), and the positive and negative percent agreement, and positive and negative predictive value were 100% (75/75), 92.7% (51/55), 94.9% (75/79) and 100% (51/51), respectively. The prevalence of tellurite-resistant KP was 16.7% (86/516) in fecal samples from healthy volunteers, among which the positive rate of terW was 100% (86/86). The antimicrobial resistance characteristics of terW+ KP showed no difference between healthy volunteers and inpatients. The most common capsular serotypes associated with high virulence were K1, K2 and K57. Conclusions: The MacConkey medium containing 4 μg/ml potassium tellurite could easily select and culture terW+ KP in fecal samples with high sensitivity and specificity, which is a practical method for the epidemic surveillance of hvKP in general population.