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Gonorrhea on Verge of Being Untreatable, CDC Warns
In a new report from the Centers for Disease Control and Prevention (CDC), researchers analyzed historical ciprofloxacin resistance data and gonorrhea incidence data to examine the possible effect of antimicrobial drug resistance on gonorrhea incidence at the population level.
Based on their findings, published in the April issue of Emerging Infectious Diseases, the authors predict that the spread of treatment-resistant gonorrhea is imminent, and that, as a result, the U.S. and the rest of the world will soon begin to see widespread outbreaks.
The authors note that Neisseria gonorrhoeae has been adept at acquiring and maintaining resistance to antimicrobial drugs used for the treatment of gonorrhea, such as penicillin, tetracyclines, and fluoroquinolones (e.g., ciprofloxacin). By 2007, the CDC no longer recommended ciprofloxacin or other fluoroquinolones to treat gonorrhea, which makes two cephalosporins — cefixime and ceftriaxone — the only remaining recommended treatment options.
In their new study, the researchers analyzed data from the Gonococcal Isolate Surveillance Project and city-level gonorrhea incidence rates from surveillance data for 17 cities during 1991–2006.
The authors first focused on simple comparisons of trends in gonorrhea incidence rates in two groups of cities in the U.S.: those with a relatively high prevalence of ciprofloxacin resistance and those with a relatively low prevalence. After conducting these comparisons, they used regression analyses to further examine the association between ciprofloxacin resistance and gonorrhea incidence.
The researchers found a strong positive association between ciprofloxacin resistance and increased gonorrhea incidence rates at the city level during 1991–2006. Moreover, their findings suggested that gonorrhea incidence rates in a scenario in which 10% of isolates were resistant to treatment would be approximately 7% higher than in a scenario of no drug resistance.
The authors offer two possible explanations for their observations: First, treatment failures or delays in the clearance of infections caused by ciprofloxacin resistance might have increased the duration of infectivity and facilitated transmission to partners. Second, mutational changes in the organism that conferred resistance or co-occurred with resistance determinants might have supported gonococcal transmission.
According to the investigators, their assessment of the association between ciprofloxacin resistance and gonorrhea incidence offers evidence that emerging cephalosporin resistance could lead to higher gonorrhea incidence rates at the population level than would have been observed in the absence of cephalosporin resistance.
“During the emergence of ciprofloxacin resistance, non-fluoroquinolone treatment options were readily available,” they write. “However, few, if any, alternative options are currently available to treat ceftriaxone-resistant infections. In this scenario of limited treatment options, the population-level effect of ceftriaxone resistance could be more substantial.”
The authors conlcude that their findings highlight the possibility of future increases in gonorrhea incidence caused by emerging cephalosporin resistance.Source: CDC; March 13, 2014.