CDC reports novel resistant meningococcus strain

Neisseria meningitidis
Neisseria meningitidis

CDC / Dan Higgins

An analysis of meningococcus isolates from US health departments has identified a novel strain of ciprofloxacin-resistant and beta-lactamase–producing Neisseria meningitidis, scientists with the Centers for Disease Control and Prevention (CDC) and the Maryland Department of Health reported today in Morbidity and Mortality Weekly Report.

The findings prompted the CDC to issue a health advisory with recommendations for healthcare providers and public health officials.

Fast treatment essential

N meningitidis is the bacterium that causes meningococcal disease, a sudden-onset, life-threatening infection of the lining of the brain and spinal cord or the bloodstream. Rates of meningococcal disease have been declining in the United States since the 1990s, according to the CDC, and only 330 total cases were reported in 2018. Rates are highest in children under the age of 1.

Historically, N meningitidis isolates in the United States have been susceptible to penicillin and ciprofloxacin, two of the antibiotics used for treatment in people with confirmed infections and for prophylaxis (prevention) in those with close contact with infected patients. Quick treatment with antibiotics is considered essential, as the disease can cause death within a matter of hours.

But this January, an isolate that produced a beta-lactamase enzyme (which breaks down beta-lactam antibiotics) and was resistant to penicillin and ciprofloxacin was cultured from a meningococcal disease patient in Maryland, followed by a second case reported by the Maryland Department of Health in February.

Those findings prompted the CDC to request isolates from meningococcal disease cases from state health departments and conduct a systematic analysis.

Scientists identify 33 resistant isolates

In today's study, whole-genome sequencing (WGS) of 2,097 N meningitidis isolates found 33 beta-lactamase–producing isolates from cases in 12 states that occurred from 2013 through 2020.

Eleven of the isolates, collected from 9 states in 2019 and 2020, belonged to N meningitidis serogroup Y (NmY) and contained both the blaROB-1 beta-lactamase gene associated with penicillin resistance and a mutation of the T91I gyrA chromosome associated with resistance to ciprofloxacin. Antimicrobial susceptibility testing confirmed resistance to penicillin and ciprofloxacin.

Twenty-two of the isolates contained blaROB-1 but did not have mutations associated with ciprofloxacin resistance. All 33 isolates belonged to clonal complex 23, and 30 belonged to sequence type (ST)-3587.

There were no known epidemiologic links among the 33 cases, but 22 (67%) occurred in Hispanic people, including 8 of the 11 cases with ciprofloxacin-resistant isolates.

"The detection of geographically diverse cases with penicillin-resistant and ciprofloxacin-resistant NmY isolates has implications for treatment and prophylaxis of meningococcal disease in the United States," the authors wrote.

CDC urges testing of isolates

In today's CDC health advisory, the agency urges providers to test meningococcal isolates for susceptibility to penicillin before changing from empiric treatment with cefotaxime or ceftriaxone to penicillin or ampicillin. The agency also called on public health officials in states that have experienced meningococcal disease caused by ciprofloxacin-resistant strains over the past 2 years to conduct susceptibility testing of isolates to inform prophylaxis decisions.

The CDC is also asking state health departments to report any suspected meningococcal treatment or prophylaxis failures.

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