Septicemia Caused by Neisseria meningitidis With Decreased Ciprofloxacin Susceptibility: The First Case Report in Korea.

Dear Editor, Several antibiotics are currently used for meningococcal prophylaxis, including ciprofloxacin, rifampin, and ceftriaxone. Ciprofloxacin, a fluoroquinolone, is often used in adults because of its convenient single-dose regimen. In contrast to an emerging trend worldwide, ciprofloxacin-resistant Neisseria meningitidis has not been reported in Korea [1, 2]. We report the first instance of septicemia caused by meningococcus with decreased ciprofloxacin susceptibility in Korea. A 20-yr-old female was admitted to the hospital with fever, rhinorrhea, sputum, and myalgia that started 24 hr before admission. The patient’s initial vital signs included a temperature of 38.3°C, a blood pressure of 91/76 mm Hg, a pulse rate of 95 beats/min, and a respiratory rate of 20 breaths/min. Physical examination revealed a pinkish rash on the lower extremities. Laboratory testing showed a white blood cell (WBC) count of 7.5×10/L (70% neutrophils) and C-reactive protein levels of 10.98 mg/dL. We suspected an infectious disease with severe sepsis, and ceftriaxone was injected intravenously. About six hours later, the rash turned into multiple petechial lesions, sized from 1 mm to 5 mm, and was purpuric and non-blanching; a meningococcal infection was suspected. She was moved to the intensive care unit (ICU) and quarantined. She complained about a severe headache as well. Cerebrospinal fluid (CSF) analysis for the differential diagnosis of meningitis showed a WBC count of 16×10/L (18% polymorphonuclear neutrophils and 70% monocytes), a red blood cell (RBC) count of 3×10/L, and glucose and protein levels of 81 and 43 mg/dL, respectively. Blood culture showed gram-negative diplococci after two days of incubation. On the fourth day of hospitalization, the isolate was identified as N. meningitidis by using VITEK 2 system (bioMérieux, Marcy l’Etoile, France). Ciprofloxacin, ceftriaxone, and trimethoprim-sulfamethoxazole susceptibility testing was performed by using the disk diffusion method according to the CLSI guidelines [2]. Test results are shown in Table 1; ciprofloxacin susceptibility was intermediate with a zone diameter of 34 mm (Fig. 1A). We confirmed the minimum inhibitory concentration (MIC) via E-test (AB Biodisk, Solna, Sweden). Our results indicated an intermediate susceptibility of the isolate to ciprofloxacin at 0.06 μg/mL (Fig. 1B). Serogrouping by PCR was performed as described previously [3]. The crgA gene was used to identify N. meningitidis, while the orf-2 gene (serogroup A) and