Antimicrobial Resistance among Campylobacter Strains, United States, 1997–2001

Abstract

We summarize antimicrobial resistance surveillance data in human and chicken isolates of Campylobacter.Isolates were from a sentinel county study from 1989 through 1990 and from nine state health departments participating in National Antimicrobial Resistance Monitoring System for enteric bacteria (NARMS) from 1997 through 2001.None of the 297 C. jejuni or C. coli isolates tested from 1989 through 1990 was ciprofloxacin-resistant. From 1997 through 2001, a total of 1,553 human Campylobacter isolates were characterized: 1,471 (95%) were C. jejuni, 63 (4%) were C. coli, and 19 (1%) were other Campylobacter species.The prevalence of ciprofloxacin-resistant Campylobacter was 13% (28 of 217) in 1997 and 19% (75 of 384) in 2001; erythromycin resistance was 2% (4 of 217) in 1997 and 2% (8 of 384) in 2001.Ciprofloxacin-resistant Campylobacter was isolated from 10% of 180 chicken products purchased from grocery stores in three states in 1999.Ciprofloxacin resistance has emerged among Campylobacter since 1990 and has increased in prevalence since 1997.C ampylobacter is the most common cause of bacterial gastroenteritis in the United States, causing an estimated 2.4 million human infections annually (1).Diagnosed infections have declined in recent years.In 2001, FoodNet surveillance identified 13.4 diagnosed Campylobacter infections per 100,000 persons (2).Approximately 95% of diagnosed Campylobacter infections are due to C. jejuni (3).Although most Campylobacter infections cause an acute, self-limited illness characterized by diarrhea, fever, and abdominal cramps, severe infections do occur (4).Antimicrobial treatment can shorten the duration of illness and may be life-saving in invasive infections (5-7).Fluoroquinolones (e.g., ciprofloxacin) are often prescribed empirically for the treatment of gastroenteritis and for Campylobacter infections in adults (6,8).Quinolones (e.g., nalidixic acid), although now seldom used for treatment in the United States, are frequently used to screen for fluoroquinolone resistance because of the close correlation between quinolone and fluoroquinolone resistance among Campylobacter.Macrolides, such as erythromycin, are also prescribed to treat Campylobacter infections (4,9).Fluoroquinolone-resistant Campylobacter infections in humans were first detected in Europe in the late 1980s (10-12).Subsequently, an increasing proportion of Campylobacter isolates around the world have been found to be fluoroquinolone-resistant (13).Studies in the United States, Europe, and New Zealand have identified poultry as a principal source of Campylobacter infection (14-16).Quinolones have been available in human medicine since the mid-1960s, and the first fluoroquinolone (ciprofloxacin) was approved for use in humans in 1986.Two fluoroquinolones, sarafloxacin and enrofloxacin, were approved for use in poultry by the U.S. Food and Drug Administration (FDA) in 1995 and 1996, respectively (17).These fluoroquinolones were the first ones approved in food animals; subsequently, other fluoroquinolones have been approved for veterinary use but not for use in poultry (18).