Emergence of Neisseria meningitidis with decreased susceptibility to ciprofloxacin in Argentina

1Servicio Antimicrobianos, Dpto Bacteriología, Instituto Nacional de Enfermedades Infecciosas (INEI)–ANLIS ‘Dr Carlos G. Malbrán’, Av. Velez Sarsfield 563 (1281), Buenos Aires; 2Hospital Area Cipolleti, Rio Negro; 3Hospital Sor María Ludovica, La Plata, Buenos Aires, Argentina; 4Reference Laboratory for Meningococci. Servicio de Bacteriología. Instituto de Salud Carlos III, Majadahonda, Spain Sir, To date, only three Neisseria meningitidis clinical isolates showing decreased susceptibility to ciprofloxacin (DSC) have been reported in France (1999), Australia (2000) and Spain (2003).1 The mechanisms of resistance were mutations in the quinolone resistance determining region (QRDR) of the gyrA gene, resulting in amino acid substitutions Asp-95→Gly, Asp-95→Asn and Thr-91→Ile, respectively.1 During 1997–2003, 873 meningococcal strains from invasive disease were submitted to the National Reference Laboratory (INEI) as part of the National Surveillance Programme for serogroup and antimicrobial resistance in N. meningitidis. In 2002, we detected one strain (M5191) with DSC (MIC 0.12 mg/L), isolated from the CSF of a 63-year-old woman at Hospital Area Cipolleti, Rio Negro Province. The woman suffered from diabetes and chronic urinary tract infections, and she had been previously treated with antibiotics, including fluoroquinolones. During 2003 a second strain (M5507) with DSC (MIC 0.06 mg/L) was isolated from both CSF and blood, in a 1-year-old child from Hospital Sor María Ludovica, La Plata, Buenos Aires Province. In this case, the patient had not been previously exposed to any antibiotic. Treatment with ceftriaxone resulted in a good clinical outcome in both cases. All other meningococci examined were susceptible to ciprofloxacin (MICs ≤0.015 mg/L).