The Niche for Sequence Type 131 Among Veterans: Urinary Tract Abnormalities and Long-Term Care Facilities.

 Antimicrobial resistance among is increasing, driven largely by the global emergence of sequence type 131 (ST131). However, the clinical significance of ST131 status is unknown. Among veterans, we assessed whether ST131 causes more severe, persistent, or recurrence-prone infections than non-ST131 .  Isolates were assessed by polymerase chain reaction for membership in ST131 and relevant subclones thereof (30R and 30Rx) and by broth microdilution for susceptibility to 11 antibiotics. Clinical and epidemiological data were systematically abstracted from the medical record. Between-group comparisons were made using tests and Fisher's exact test.  Of the 311 unique isolates, 61 (19.6%) represented ST131. Of these, most (51 of 61, 83.6%) represented the 30R subclone; only 5 of 51 (9.8%) represented 30Rx. Relative to non-ST131 and non-30R isolates, neither ST131 nor 30R were associated with more severe disease, worse clinical outcomes, or more robust hosts. Instead, both were more likely to be isolated from patients without manifestations of infection (for ST131, 36.1% vs 21.2% [ = .02]; for 30R, 39% vs 21% [ = .008]) and who had prior healthcare contact or long-term care facility (LTCF) exposure (for ST131, 33% vs 14% [ = .002]; for 30R, 37% vs 14% [ < .001]). Despite a greater likelihood of discordant initial therapy, outcomes did not differ between ST131 and 30R isolates vs other isolates.  Among veterans, ST131 and its 30R subclone were associated with LTCF-exposed hosts but not with worse outcomes.