Emerging in Vitro Resistance to Quinolones in Penicillinase-producing Neisseria Gonorrhoeae Strains in Hawaii

The susceptibilities of 37 penicillinase-producing strains of Neisseria gonorrhoeae (PPNG), isolated in Hawaii from December 1991 through January 1994, were determined to ciprofloxacin and ofloxacin, fluoroquinolone agents currently recommended by the Centers for Disease Control and Prevention as alternative regimens for the treatment of uncomplicated gonorrhea. Nine isolates (24.3%) exhibited decreased susceptibilities (MICs, > or = 0.06 microgram/ml) to ciprofloxacin and ofloxacin. Ciprofloxacin MICs for three isolates (8.1%) were 2.0 micrograms/ml; these isolates belonged to the auxotype/serovar class Pro/IB-7 and possessed the 3.2-MDa beta-lactamase and the 24.5-MDa conjugative plasmids. Six strains for which ciprofloxacin MICs were 0.06 to 0.125 microgram/ml belonged to a variety of gonococcal phenotypes. Strains for which ciprofloxacin MICs were 2.0 micrograms/ml were isolated from persons who had traveled to, or were sexual contacts of persons who had recently traveled to, Southeast Asia. Persons infected with these isolates had been treated with ceftriaxone (250 mg intramuscularly, single dose); therefore, none of these cases were associated with clinical failure following the use of fluoroquinolone therapy. Further studies are needed to confirm the clinical and public health significance of increased in vitro resistance to ciprofloxacin and ofloxacin in N. gonorrhoeae.