Neisseria meningitidis has remained highly susceptible to antibiotics, and resistance to penicillin G and chemoprophylaxis agents is uncommon, according to data from an active population-based surveillance program.
“Antimicrobial susceptibility surveillance of isolates of N. meningitidis collected in 2004, 2008, 2010 and 2011 provides reassuring data that nonsusceptibility to antimicrobials commonly used for treatment and chemoprophylaxis of meningococcal disease is stable and low in the United States,” researcher Brian H. Harcourt, PhD, of the meningitis and vaccine preventable diseases branch of the CDC, and colleagues wrote in Open Forum Infectious Diseases.
The researchers tested 466 N. meningitidis isolates collected over several years from the Active Bacterial Core Surveillance (ABC) system to test for susceptibility to ceftriaxone, ciprofloxacin, penicillin G, rifampin and azithromycin. The ABC, an active, laboratory and population-based surveillance system, operates in 10 states or areas and includes about 13% of the U.S. population. They tested susceptibility with broth dilution.
Results indicated that 87.1% of the isolates were susceptible to all of the antimicrobials tested. In all, 10.3% were penicillin G intermediate, ranging from 8% in 2008 to 16.7% in 2010. Less than 1% of isolates were resistant to ciprofloxacin, rifampin or penicillin G. In addition, 63% of penicillin G intermediate or resistant isolates had mutations in the penA gene, which is associated with reduced susceptibility to penicillin G.
“The clinical significance of the increase in the proportion of penicillin G intermediate isolates is unknown; however, the proportion of penicillin G intermediate isolates among fatal cases was low,” Harcourt and colleagues wrote.
The researchers recommended periodic surveillance of circulating N. meningitidis to monitor susceptibility trends. – by Colleen Owens
Disclosure: The researchers report no relevant financial disclosures.