Antibiotics are not usually recommended for treating E. coli infections; however one of these drugs showed promising results when given to victims of last year’s massive European outbreak linked to sprouts.
Azithromycin, administered to patients to prevent the spread of meningitis, was associated with a shorter duration of shedding of the E. coli O104:H4 bacteria in stool specimens according to a study published in the March 14 issue of JAMA (Journal of the American Medical Association).
Patients who received azithromycin were also less likely to carry the bacteria long-term.
Out of a group of 65 patients treated at the University Hospital Schleswig-Holstein in Lubeck, Germany, 22 were given the drug and 43 received no antibiotic treatment. Patients who received the drug (both in-patients and out-patients) were treated approximately 12 days after they started showing symptoms of infection.
After 21 days, only 31.8 percent of the treated group were still carriers of the bacteria, whereas 83.7 percent of those not treated continued to be Shiga toxin-producing E. coli (STEC) carriers.
Long-term carriage was measured starting at day 28. At this time, 4.5 percent of those treated carried the bacteria. That percentage was 81.4 among those not treated with azithromycin. At day 35, none of the treated patients was still an STEC carrier. However 8 days later, at day 43, 57.7 percent of the control group was still carrying the bug.
Long-term carriage of STEC can be dangerous both to those exposed to the patient, who is infectious, and to the individual himself.
“Long-term carriers of entheropathogenic bacteria represent a chronic risk of human-to-human transmission and, therefore their individual social and working life is legally restricted by the German health authorities, posing a high psychological and socioeconomic burden,” says the report, according to Science Daily.
These patients also risk persistent diarrheal symptoms, according to the authors.
The jury is still out on whether or not azithromycin can be used to treat STEC patients, in addition to reducing the endurance of the disease. A major concern in STEC treatment is preventing the onset of hemolytic uremic syndrome, or HUS, a potentially life-threatening complication that affects the kidneys.
“Clinicians should not consider these data as an endorsement of the safety or efficacy of using azithromycin to treat diarrhea caused by Shiga toxin-producing E. coli, because the subjects in this study were treated late in illness well after the outcome of greatest concern, i.e., HUS, had already ensued,” warns Dr. Phillip Tarr, Co-Leader of the Pathobiology Research Unit and Director of the Division of Gastroenterology and Nutrition at the Washington University School of Medicine’s Department of Pediatrics.
While the study was “very well done,” he says, “its applicability is limited to the carriage state, after the most severe phase of illness has passed,” he noted in an emailed statement to Food Safety News.
It is possible, however, that future research on the drug may reveal an ability to combat STEC symptoms.
Azithromycin could be “a safe therapeutic option for the treatment of [Shiga toxin-producing enterohemorrhagic E. coli] diarrhea to avoid development of HUS,” said Dr. Johannes Knobloch of the University of Luebeck when presenting the preliminary results of this study at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Chicago last September.
However, a prospective trial would need to be conducted to test this potential, he noted.
The European outbreak, which began in May of 2011 and was eventually linked to sprouts grown from fenugreek seeds, sickened 3,816 people in that country alone and over 4,000 people total. Of all victims, 852 developed HUS and 50 died from both HUS and non-HUS infections.
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