First invasive isolate of Neisseria meningitidis (Nme) showing decreased susceptibility to ciprofloxacin (DSC) in Argentina (ARG)

CORSO A; MIRANDA M; FACCONE D; JORDA L; REGUEIRA M; CARRANZA C; CASTRO N; GALAS M

Washington, USA

Congreso; 44 th Interscience Conference of Antimicrobial Agents and Chemotherapy; 2004

Today, only three Nme with DSC has been reported worldwide: in France (1999), Australi (2000) and Spain (2003). The resistance mechanism involved mutations in the QRDR of gyrA, Asp95-Gly or Asn or Thr91-  Ile. In 2002, the Nme 5191 was isolated from CSF from a 63 years old female with meningitis, in the HAC, Rio Negro. The strain was submitted to the national reference laboratory (INEI) to determine the serogroup and susceptibility profile as a part of the program surveillance of Nme isolates from invasive diseases. Nme 5191 showed DSC. Aim: to characterize the first Nme with DSC in ARG. Methods: serogroup and serotype/serosubtype were determined by slide agglutination and ELISA, respectively. MICs to nalidixic acid (NAL) and ciprofloaxin (CIP) were assessed with and without 6.25 mg/L of reserpin, and inhibitor of several types of efflux pumps. Nme EMGM-2, -10, -13, were used as CIP susceptible control strains. Amplification and sequencing of QRDR of gyrA and parC genes were performed by standard methods. Results: Nme 5191 was characterized as Y:NT:P1.5. The strain was susceptible to (MIC mg/L): penicillin (0.03), ampicilin (0.06), ceftriaxone (0.001), rifampicin (0.008), chloramphenicol (0.5) and tetracycline (0.12), but displayed the DSC (0.12) and NAL resistance (64). QRDR of gyrA and parC genes did not shown mutations as compared to the QRDR of susceptible meningococcal strain. The addition of reserpin reducer de MICs of CIP and NAL to 0.004 and 0.5 mg/L, respectively, but the MICs of Nme control strains remain unchanged. Conclusion: this is the first Nme with DSC described in Arg and the fourth worldwide. The absence of mutations in QRDR of gyrA and parC genes and the reserpin-dependent reduction in the MICs of CIP and NAL suggest the presence of an efflux mechanism