Inhibitory Activity of Systemic Antibiotics Against Clostridium difficile

Systemic antibiotics vary widely in in vitro activity against Clostridium difficile. Some agents with activity against C. difficile (e.g., piperacillin/tazobactam) inhibit establishment of colonization in mice. Kundrapu, et al. (2016) tested the hypothesis that piperacillin/tazobactam and other agents with activity against C. difficile achieve sufficient concentrations in the intestinal tract to inhibit colonization in patients.

Point-prevalence culture surveys were conducted to compare the frequency of asymptomatic rectal carriage of toxigenic C. difficile among patients receiving piperacillin/tazobactam or other inhibitory antibiotics (e.g. ampicillin, linezolid, carbapenems) versus antibiotics lacking activity against C. difficile (e.g., cephalosporins, ciprofloxacin). For a subset of patients, in vitro inhibition of C. difficile (defined as a reduction in concentration after inoculation of vegetative C. difficile into fresh stool suspensions) was compared among antibiotic treatment groups.

Of 250 patients, 32 (13 %) were asymptomatic carriers of C. difficile. In comparison to patients receiving non-inhibitory antibiotics or prior antibiotics within 90 days, patients currently receiving piperacillin/tazobactam were less likely to be asymptomatic carriers (1/36, 3 versus 7/36, 19 and 15/69, 22 %, respectively; P = 0.024) and more likely to have fecal suspensions with in vitro inhibitory activity against C. difficile (20/28, 71 versus 3/11, 27 and 4/26, 15 %; P = 0.03). Patients receiving other inhibitory antibiotics were not less likely to be asymptomatic carriers than those receiving non-inhibitory antibiotics.

The researchers says their findings suggest that piperacillin/tazobactam achieves sufficient concentrations in the intestinal tract to inhibit C. difficile colonization during therapy.

Reference: Kundrapu S, Sunkesula VCK, Jury LA, Cadnum JL, Nerandzic MM, Musuuza JS, Sethi AK and Donskey CJ. Do piperacillin/tazobactam and other antibiotics with inhibitory activity against Clostridium difficile reduce the risk for acquisition of C. difficile colonization? BMC Infectious Diseases. 2016;16:159.