The Centers for Disease Control and Prevention (CDC) has reported observing a significant increase in the number of meningococcal disease cases with isolates containing a blaROB-1 β-lactamase enzyme gene, conferring resistance to penicillin antibiotics and, in some cases, ciprofloxacin as well, according to the CDC’s Morbidity and Mortality Weekly Report

Antibiotics used for treatment and prophylaxis of meningococcal disease caused by the bacterium Neisseria meningitidis include penicillin and ciprofloxacin, respectively, and, until recently, resistance to these agents in the US has been rare. However, after a number of penicillin- and ciprofloxacin-resistant N. meningitidis serogroup Y (NmY) isolates had been detected in the first several months of 2020, members of the CDC’s Antimicrobial-Resistant Neisseria meningitidis Team conducted a systematic analysis in order to assess whether the pattern of resistance was more widespread. 

State health departments were asked to submit isolates from meningococcal disease cases every 6 months. Whole genome sequencing (WGS) was performed on all isolates from invasive meningococcal disease cases that occurred between 2011 and 2020 to determine whether the blaROB-1 β-lactamase gene or mutations associated with ciprofloxacin resistance were present. 

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“CDC identified 33 meningococcal disease cases occurring between 2013 and 2020 that were caused by NmY isolates containing a blaROB-1 β-lactamase enzyme gene conferring resistance to penicillins,” the study authors reported. These cases occurred in 12 geographically disparate states and 67% (22/33) of cases involved Hispanic patients. “Isolates from 11 of these cases, reported during 2019–2020 from 9 states, were also resistant to ciprofloxacin,” they added. 

To address the issue, the CDC is recommending that antimicrobial susceptibility testing (AST) be utilized to determine the susceptibility of all meningococcal isolates to penicillin before switching from empirical treatment with cefotaxime or ceftriaxone to penicillin or ampicillin. Secondly, AST should be considered for meningococcal isolates occurring in states that have experienced ciprofloxacin-resistant meningococcal disease cases in the past 2 years so that more informed decisions on prophylaxis therapy can be made. 

Additionally, state health departments should continue to submit all meningococcal isolates for AST and WGS and also report any suspected treatment or prophylaxis failures. Any isolates that have screened positive for β-lactamase or are ciprofloxacin-resistant should be reported to the CDC. 

“Ceftriaxone and cefotaxime can continue to be used for empiric bacterial meningitis treatment; meningococcal isolate susceptibility to penicillin should be determined before switching to penicillin or ampicillin,” the team concluded, adding that “Prophylaxis failures and antimicrobial resistance among meningococcal isolates should be monitored to inform meningococcal prophylaxis recommendations.”


McNamara LA, Potts C, Blain AE, et al. Detection of ciprofloxacin-resistant, β-lactamase–producing Neisseria meningitidis serogroup Y isolates — United States, 2019–2020. MMWR Morb Mortal Wkly Rep 2020;69:735–739. doi: 10.15585/mmwr.mm6924a2.

This article originally appeared on MPR