E. coli bacterial carriage shorter when azithromycin prescribed

A study, published in the March 14 issue of JAMA , reveals that treatment with azithromycin during the E coli outbreak in Germany in May 2011, was linked to a shorter period of the bacteria being carried and excreted via stool specimens. The researchers explain: "Since May 2011, a large outbreak of Shiga toxin-producing Escherichia coli (STEC) has caused 3,816 documented infections in Germany, including 845 confirmed cases of hemolytic uremic syndrome [HUS; a condition characterized by the breakup of red blood cells and kidney failure]. According to existing recommendations, antibiotic treatment of STEC infection is discouraged because this therapy might increase the risk of HUS development." They note that carrying bacteria for a long time can result in persistent diarrheal symptoms. "Moreover, long-term carriers of enteropathogenic [capable of causing disease in the intestinal tract] bacteria represent a chronic risk of human-to-human transmission and, therefore, their individual social and working life if legally restricted by the German health authorities, posing a high psychological and socioeconomic burden." To date, no data on long-term STEC carriage for this outbreak has been published. Martin Nitschke, M.D., of the University Hospital Schleswig-Holsteinm Lubeck, Germany, and his team conducted a study in order to examine the duration it took patients with this infection receiving treatment with azithromycin to excrete the bacteria via stool specimens, compared to patients without antibiotic treatment. Prophylactic azithromycin treatment was administered to a considerable number of patients during this outbreak as part of a therapeutic regimen with the C5 antibody eculizumab. The researchers enrolled 65 individuals with STEC infection, as well as patients with HUS and STEC-infected outpatient without manifestations of HUS, between May 15 and July 26, 2011, to participate in the study. Following onset of clinical symptoms, the team monitored participants for an average of 39.3 days. 22 participants received azithromycin, while 43 participants received no antibiotic treatment. On average, participants in the azithromycin group began treatment 11.8 days after the onset of clinical symptoms. Between the two groups the researchers found no considerable differences in age or sex distributions. Among participants receiving azithromycin, the team found there was a substantially lower number of STEC carriers. The researchers said: "At day 21, rates of STEC carriage were 31.8 percent in the initially treated group and 83.7 percent in those not treated. Long-term carriage (at day 28) was 4.5 percent in the treated group and 81.4 percent in the untreated group. At day 35, no patient in the treated group was a STEC carrier and all patients remained STEC-negative after the completion of 14 days of treatment. In contrast, 25 of 43 (57.7 percent) in the control group were STEC carriers at day 42 after onset of clinical symptoms." Results from the study led the researchers to provide azithromycin treatment for 15 participants with remaining symptoms. All 15 participants had at least 3 STEC-negative stool specimens after completion of treatment. The researchers found no indicators of HUS induction as a result of azithromycin therapy. They conclude: "These findings warrant confirmation for other STEC strains, as well as prospective evaluation and possible clinical trials."