FQ-resistant N. gonorrhoeae strains originated in the 1980s, and subsequently spread through the continental U.S. shortly after 2000. In 2007, the CDC updated the gonorrhea treatment guidelines to no longer include FQ as first-line therapy and recommended monitoring local resistance patterns to guide treatment recommendations. In 2010, guidelines were updated to no longer recommend oral cephalosporins as treatment for gonorrhea. Public Health – Dayton & Montgomery County (PHDMC) STD Clinic tested 102 consecutive N. gonorrhoeae isolates for FQ-resistance in 1996, 106 consecutive isolates in 2000, and 286 randomly selected isolates from 2006-2008 to identify susceptibility trends in the region.
Since Aug 2011, cultures for N. gonorrhoeae have been collected from male and female patients presenting to the PHDMC STD Clinic. Susceptibility testing was performed on isolates using Etest strips for ceftriaxone (CEF) and ciprofloxacin (CIP). Susceptibility testing for azithromycin (AZM) began in Aug 2014. Susceptibility results were interpreted based on the following criteria: resistance to CIP defined as MIC ≥1 μg/mL; reduced susceptibility to AZM defined as MIC ≥ 2 μg/mL; reduced susceptibility to CEF defined as MIC ≥ 0.125 μg/mL (as per CDC guidelines).
There were no isolates resistant to CIP in 1996 or 2000. From 2006-2008, 1.7% were resistant to CIP. From Aug 2011 – Dec 2014, 383 isolates were tested; 0.8% were resistant to CIP. In 2014, 22 isolates were tested and none showed reduced susceptibility to AZM. In 2015, 53 isolates were tested; none were resistant to CIP and 1.9% showed reduced susceptibility to AZM. In 2016 (though July 31), 51 isolates have been tested; 15.7% were resistant to CIP and 5.9% showed reduced susceptibility to AZM. No isolates tested from 2011-2016 showed reduced susceptibility to CEF.
There has been a rapid emergence of CIP and AZM resistance in Dayton and Montgomery County. No decreased susceptibility to CEF was found during the period of the study. These results demonstrate that local susceptibility testing provides important information for clinical decision-making.