Analysis on antibiotic susceptibility of Neisseria meningitidis isolates in China,2003-2012

Objective To understand the antibiotic susceptibility of Neisseria meningitidis strains isolated in China during 2003-2012. Methods A total of 487 N. meningitidis isolates were selected from our laboratory collection according to the isolation year, serogroup and sources(patient or healthy carrier). The susceptibilities of these strains to 12 antibiotics was tested by using broth microdilution susceptibility test and E-test according to the Clinical and Laboratory Standard Institute(CLSI) guidelines. Results All the N. meningitidis strains were sensitive to cefotaxime, ceftriaxone, azithromycin, meropenem, chloramphenicol and minocycline, and 4.9%(24/487) and 3.5%(17/487) of the isolates were less sensitive to penicillin and ampicillin respectively. The resistant rates to nalidixic acid, cotrimoxazole and ciprofloxacin were 75.6%(368/487), 87.1%(424/487) and 48.9%(238/487) respectively. The ciprofloxacin-resistance was first detected in 2005 when the resistant isolates accounted for 23.8%(24/101); the strains with decreased sensitivity to penicillin were first detected in 2006(2.4%, 2/82). The strains from patients and healthy carriers showed different resistance to nalidixic acid, cotrimoxazole and ciprofloxacin. Conclusion The N. meningitidis strains isolated in China from 2003 to 2012 were highly resistant to sulfonamides and quinolones, but they showed low resistance to penicillin. The resistance was associated with the isolation year, serogroup and sources of the isolates.