Ciprofloxacin susceptibility profiles of the Los Angeles and Chicago USA300 household MRSA isolates and SNPs in their grlA and gyrA genes

HouseholdRegionnaCiprofloxacin susceptibilityb (MIC [μg/ml])grlA position 80 nucleotidegyrA position 84 nucleotide
8010Los Angeles7R (>4.0)YL
8012Los Angeles11R (>4.0)YL
8013Los Angeles3S (1.0)SS
8035Los Angeles8S (1.0)SS
8036Los Angeles3R (>4.0)YL
8056Los Angeles3R (>4.0)YL
8113Los Angeles8R (>4.0)YL
8174Los Angeles5R (>4.0)YL
8182Los Angeles6R (>4.0)YL
8203Los Angeles9R (>4.0)YL
8211Los Angeles7R (>4.0)YL
8217Los Angeles1NDcYL
9002Chicago12S (0.5)SS
9011Chicago9R (>4.0)YL
9012Chicago5S (0.5)SS
9032Chicago6S (0.5)SS
9033dChicago13S (0.5)SS
9101Chicago9R (>4.0)YL
9131Chicago5S (1.0)SS
9141eChicago5R (>4.0)YL
9150Chicago11S (0.5)SS
  • a Number of isolates sequenced in the household.

  • b R, resistant; S, susceptible.

  • c ND, MIC not determined.

  • d One isolate (120381) in household 9033 had grlA 80F and gyrA 84L SNPs and was ciprofloxacin sensitive.

  • e One isolate (119813) in household 9141 did not have these SNPs.