In patients with hematologic malignancies, receipt of prophylactic levofloxacin was associated with less disruption of the gut microbiome than treatment with broad-spectrum beta-lactams, or BSBLs, according to findings from a retrospective cohort study.
“The impact of antibiotics on the microbiome likely depends on both host factors and the specific antibiotic agent used,” Matthew Ziegler, MD, MSCE, an infectious disease fellow at the University of Pennsylvania Perelman School of Medicine, told Infectious Disease News. “In our study we aimed to investigate the gut microbiome impact of prophylactic levofloxacin, which has been shown to reduce exposure to broad-spectrum beta-lactam antibiotics by preventing bloodstream infection and neutropenic fever in patients receiving treatment for hematologic malignancy.”
The study included 60 patients who were admitted to the Hospital of the University of Pennsylvania between Feb. 13, 2017, and Nov. 17, 2017, for chemotherapy or stem cell transplant. According to the study, 42% of the included patients had acute myeloid leukemia, 37% had multiple myeloma and 11% had non-Hodgkin lymphoma. The median age was 63 years, and 47% were female.
Ziegler and colleagues reported that 17 patients received a BSBL, 17 received levofloxacin, four received both a BSBL and levofloxacin and 22 received neither. According to the findings, the gut microbiome of patients treated with BSBLs demonstrated significantly reduced Shannon’s alpha diversity (median = 3.28; interquartile range [IQR], 1.73-3.71) compared with patients who were not exposed to a BSBL (median = 3.73; IQR, 3.14-4.31; P = .01). The researchers found that the gut microbiome of patients treated with levofloxacin demonstrated increased Shannon’s alpha diversity (median = 3.83; IQR, 3.32-4.36) compared with patients who did not have a levofloxacin exposure (median = 3.32; IQR, 2.35-4.02; P = .03).
“This suggests that antibiotic prophylaxis with levofloxacin may not be as disruptive to the gut microbiome as previously thought,” Ziegler said.
Ziegler and colleagues also observed an association between levofloxacin exposure and a trend toward lower risk for dominance of non-Bacteroidetes genera. Specifically, 14% of patients who received levofloxacin experienced dominance of non-Bacteroidetes genera compared with 38% of patients who did not receive levofloxacin. According to Ziegler and colleagues, prior research has demonstrated the “potential clinical significance of Bacteroidetes taxa for the resistance to colonization with pathogens.”
Ziegler said the study showed that levofloxacin exposure resulted in greater bacterial diversity, whereas BSBL antibiotic exposure resulted in reduced diversity.
“Many studies have shown associations of the gut microbiome with important clinical outcomes in patients with hematologic malignancy, including risk of infection, graft-versus-host disease, and even mortality. If the gut microbiome is important in mediating these events, it is important to understand how our antibiotic therapies impact the gut microbiome,” Ziegler said.
“Our findings suggest that prophylactic levofloxacin may prevent disruption of the gut microbiome by preventing further exposure to broad-spectrum beta-lactam antibiotics. Additional study is needed in this area, however, and we hope to conduct large-scale microbiome analyses of antibiotic exposure in this population.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.