Objective: To develop and evaluate a rapid multiplex-quantitative polymerase chain reaction (qPCR) to identify fecal carriers of multidrug-resistant extraintestinal pathogenic Escherichia coli (MDR-ExPEC) clonal groups.
Methods: Men presenting for transrectal prostate biopsy (TPB) at the San Diego Veterans Affairs Medical Center underwent rectal culture immediately before TPB. Rectal swabs were streaked onto ciprofloxacin-supplemented (4 mg/L) MacConkey agar plates, identified, and susceptibility tested. The same swab was sent to the University of Washington for qPCR test (EST200) targeting 2 major MDR-ExPEC clonal groups--ST131 and ST69--that combined were expected to represent majority of fluoroquinolone (FQ)- and trimethoprim-sulfamethoxazole-resistant E coli. We calculate test characteristics including the area under the receiver operative curve (AUC).
Results: We enrolled 104 men from 11/5/2013 to 6/10/2014. FQ-resistant E coli were cultured from 19.2% (20/104) of rectal swabs, and 26% (27/104) of all swabs were positive for EST200 by PCR. The test characteristics comparing the EST200 to the culture-based detection of FQ resistance were 75%, 86%, 94%, and 56%, respectively. The AUC was 0.84 for the EST200 to detect FQ resistance before TPB.
Conclusion: Compared to the reference standard rectal culture, EST200 was able to detect majority of FQ-resistant E coli on rectal swabs before prostate biopsy.
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