Isolation and Characterization of Multiply Antibiotic-Resistant Clostridium perfringens Strains from Porcine Feces

Abstract

Multiply antibiotic-resistant strains of Clostridium perfringens were isolated from porcine feces. Strains that were resistant to tetracycline, erythromycin, clindamycin, and lincomycin were isolated, but no penicillin-or chloramphenicolresistant strains were obtained. Typical miniimal inhibitory concentrations for resistant strains were 16 to 64 ,ug of tetracycline per ml, 64 to >128 ,ug of erythromycin per ml, 2128 ,ug oflincomycin per ml, and 16 to 128 ,tg of clindamycin per ml. Resistance to erythromycin was always associated with resistance to lincomycin and clindamycin. Minimal inhibitory concentrations were determined for 258 strains from six farms that used antibiotics in their feeds and 240 strains from five farms that did not use antibiotics. The results show that 77.9 and 22.7% of the strains from the former farms were resistant to tetracycline and erythromycin-clindamycin-lincomycin, respectively. The comparable data from the latter farms were 25.0 and 0.8%, respectively. Agarose gel electrophoresis failed to reveal a plasmid band that was common to the resistant strains but absent in the susceptible strains. Attempts to transfer tetracycline, erythromycin, and clindamycin resistance from one strain, CW459, were not successful. Antibiotic-susceptible mutants were not isolated from this strain, despite the use of a variety of curing agents.

Distribution of Tetracycline Resistance Gene, tet(M), in Gram-Positive and Gram-Negative Bacteria Isolated from Sediment and Seawater at a Coastal Aquaculture Site in Japan

“…The administered drug may not only apply selective pressure to retain the resistance gene but also may force the transfer of the resistance gene in the aquaculture environment. Further, one of the alleles tet(M)-A was identical to a sequence found in both Streptococcal agalactiae 36) and Clostridium perfringence 28,30) , suggesting the existence of gene flow not only between strains in the aquaculture environment but also between strains from the terrestrial and coastal environment.…”

Influence of Gastric Acid on Susceptibility to Infection with Ingested Bacterial Pathogens

“…After overnight growth at 37°C, a 3-ml aliquot was used to inoculate 90 ml of preboiled fresh Trypticase-peptone-glucose medium (27), which was then incubated for 4 h at 37°C. The cells were collected by centrifugation, washed once with sterile phosphate-buffered saline (PBS), and resuspended in 2 ml of PBS prior to inoculation into mice.…”

Toxin Plasmids of Clostridium perfringens

“…4). Both the pCPF5603-and pCPF4969-like toxin plasmids contain two regions (dam-rep) and tcp, which are also present on the pCW3 tetracycline resistance plasmid (13,14,18,23,227,235,236). Since the tcp region has homology with Tn916, which is a conjugative transposon, it is conceivable that a Tn916-like transposon may have integrated into a plasmid, creating a conjugation-capable precursor plasmid (13,236).…”

“…While early studies of C. perfringens plasmids focused primarily on antibiotic resistance and bacteriocin plasmids (224)(225)(226)(227)(228)(229)(230)(231)(232), the first linkage of C. perfringens toxin production with plasmids occurred over 30 years ago, when loss of CPB production was shown to correlate with the disappearance of a plasmid from a type C strain (233). Later studies then definitively localized several toxin genes to extrachromosomal DNA in a few C. perfringens strains (234).…”

“…Analysis of the conjugation mechanism in C. perfringens has focused on the tetracycline resistance plasmid pCW3 (224,227,228), which is 47,263 bp and encodes 51 potential open reading frames (236). As mentioned above, a conjugation locus of 11 genes, intP to tcpJ, has been designated the transfer of clostridial plasmid (tcp) locus.…”