In Vitro Antimicrobial Susceptibility of Brachyspira pilosicoli Isolates from Humans

Abstract

The in vitro antimicrobial susceptibility of the anaerobic intestinal spirochete Brachyspira pilosicoli was investigated by an agar dilution method. Human (n ‫؍‬ 123) and porcine (n ‫؍‬ 16) isolates were susceptible to metronidazole, ceftriaxone, meropenem, tetracycline, moxifloxacin, and chloramphenicol; erythromycin and ciprofloxacin were not active. Resistance to amoxicillin and clindamycin varied. Amoxicillin susceptibility was restored by clavulanic acid.Brachyspira (previously Serpulina) pilosicoli is an anaerobic intestinal spirochete which colonizes the large intestines of pigs, numerous other farmed and wild animals, and humans (25). In humans, B. pilosicoli is one cause of intestinal spirochetosis, a condition characterized by end-on attachment of the organism to colorectal epithelial cells (9,16,21). In several reports, intestinal spirochetosis was the only abnormal finding for patients with abdominal pain, rectal bleeding, and diarrhea, and many of these symptoms were long-term or recurrent (4,12,16).B. pilosicoli has been isolated at a prevalence of 10 to 30% from the feces of a range of different human population groups, including Aboriginal Australians (3, 15), individuals from developing countries (2, 3, 23), homosexual males, and human immunodeficiency virus-positive individuals (21).

Penicillin-Binding Proteins in the Pathogenic Intestinal Spirochete Brachyspira pilosicoli

“…The therapeutic responses of patients with B. pilosicoli infections and the in vitro sensitivities of B. pilosicoli to ␤-lactam antibiotics are consistent with the identification of PBPs in this spirochete (2,3,(13)(14)(15). The demonstration of PBPs in intact B. pilosicoli cells suggests that the cell membrane is permeable to ␤-lactam antibiotics.…”

Antimicrobial susceptibility ofBrachyspiraspp. isolated from commercial laying hens and free-living wild mallards (Anas platyrhynchos)

“…b-Lactam antibiotics are among the most widely used antibiotics in both humans and livestock. Decreased susceptibility to b-lactam antibiotics has been reported in Brachyspira isolates from pigs (Dassanayake et al, 2005;Mortimer-Jones et al, 2008), humans (Tompkins et al, 1987;Brooke et al, 2003;Dassanayake et al, 2005;Meziane-Cherif et al, 2008;Mortimer-Jones et al, 2008), and chickens (Hampson et al, 2006b). Except for the early paper by Tompkins et al (1987), in which isolates were not identified to species level, all the isolates displaying decreased susceptibility to b-lactam antibiotics were identified as B. pilosicoli.…”

Antimicrobial susceptibility testing ofBrachyspira intermediaandBrachyspira pilosicoliisolates from Australian chickens

“…Previously, certain human and porcine isolates of B. pilosicoli have been shown to be resistant to amoxicillin (Brooke et al ., 2003). In that study resistance was associated with beta-lactamase enzyme activity, and it was suggested that this could have been acquired by horizontal transfer of beta-lactamase genes from other Brachyspira strains or bacterial species.…”