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Fluoroquinolone Resistance in the Wild

Amesh A. Adalja, MD, FACP, FACEP, FIDSA, December 4, 2015

Antimicrobial-resistant organisms are usually first noticed in hospitals, nursing homes, and other healthcare facilities and only later found to be lurking in the community as well—both colonizing and causing disease. MRSA has been a perfect example of this pattern. Community-dwelling resistant strains are important for many reasons, including the fact that it is very hard to control dissemination in community settings. In healthcare facilities, hand washing, isolation, and extensive cleaning of rooms can be enforced to a degree not feasible in a household. A new paper by Gurnee and colleagues published in the Journal of Infectious Diseases assesses the community presence of ciprofloxacin-resistant Escherichia coli colonization in newborns and their mothers. 


Stool Samples Positive in 3%

In this study, Gurnee and colleagues sampled the stool of 40 mothers and their 80 newborns (twins) for a median of 890 days to assess the presence of ciprofloxacin-resistant E. coli. Of the nearly 2,000 stool samples obtained, approximately 3% were positive at some time for the bacterium; 19% of newborns and 20% of mothers were positive at some time during the study. 

Only 2 factors were noted to be statistically more common in newborns with ciprofloxacin-resistant E. coli: an initial hospital stay that was a median of 6 days longer and a mother who was more likely to be colonized herself. Strikingly, no other variables—many of which have biological plausibility—were found to be associated, including antibiotic use in the first 2 months of life, maternal use of perinatal antibiotics, and gastric acidity–reducing medications.

Interestingly, 91% of bacteria isolated were of one strain, E. coli ST131-H30, and 89% were resistant to at least one other antimicrobial. 


Inevitable March

Antibiotic resistance is never a surprise, as our antibiotics are largely derived from other species. Though quinolones were synthetically made, they have since been found in other species in which they have various functions. Since antibiotic resistance is a known and expected occurrence, it is important to use antibiotics judiciously. As Brad Spellberg and my University of Pittsburgh colleague Yohei Doi write in the accompanying editorial, “fire and forget” fluoroquinolone prescribing policies that are premised on widespread susceptibility of E. coli, the major cause of community-acquired urinary tract infections, are no longer safe, as resistance rates have reached 30% in some US communities. In their important study, Gurnee and colleagues have provided more evidence that the spread of antibiotic resistance and its impact on human health is one of the most challenging problems medicine has faced, and its solution will determine the fate of modern medicine.



Gurnee EA, Ndao IM, Johnson JR, et al. Gut colonization of healthy children and their mothers with pathogenic ciprofloxacin-resistant Escherichia coli. J Infect Dis 2015;212:1862-1868.

Spellberg B, Doi Y. The rise of fluoroquinolone-resistant Escherichia coli in the community: scarier than we thought. J Infect Dis 2015;212:1853-1855.