Genetic characterization of plasmid-encoded multiple antibiotic resistance in a strain ofListeria monocytogenes causing endocarditis

Abstract

One susceptible and two multiply resistant isolates of Listeria monocytogenes from a patient suffering from prosthetic valve endocarditis are described. They could not be distinguished by several typing methods. Two isolates were resistant to chloramphenicol, macrolide/lincosamide/streptogramin antibiotics and tetracycline. The resistance determinants were located on a 39 kb plasmid pWDB100 that was transferable by filter mating to several gram-positive bacteria. Evidence was obtained to support the hypothesis that the resistant variant had primarily infected the patient's blood and prosthetic valve, and later lost the resistance plasmid. The three resistance determinants showed homology to other known markers, cat221/cat223, ermB and tetM, which are frequently found in different gram-positive genera. Plasmid pWDB100 showed extensive homology to the Streptococcus agalactiae broad-host-range plasmid pIP501. It was also very similar to two listerial plasmids found in France. Thus, plasmid pWDB100 and the homologous plasmids from France, although isolated in geographically distant regions, may illustrate spread of a plasmid and its relatives.

Antibiotic resistant pattern of environmental isolates of Listeria monocytogenes from Ado-Ekiti, Nigeria

“…Environmental factors like previous exposure, the type of antibiotic used in the respective locality, and incidence of plasmids in the isolates may have resulted to the antibiotics resistance. This has been found in several isolates of L. monocytogenes (Hadorn et al, 1993;Yutaka et al, 2004). Such plasmid could be pheromones-responsible or broad-host-range (Rice et al, 1995).…”

Identification of the mechanisms of resistance and potential cross resistance of Listeria monocytogenes upon adaptation to different antimicrobials

“…monocytogenes is usually susceptible to a wide range of antibiotics, except cephalosporins and fosfomycin (102,103,153), and multidrug-resistant clinical isolates appear to be rare (97,176,180,208 In addition to antibiotic-related exposures, L. monocytogenes is expected to be frequently subjected to selection pressures associated with the extensive use of disinfectants such as quaternary ammonium compounds in food processing plants and healthcare settings. Limited information is currently available on possible cross-resistance following exposure to antibiotics such as ciprofloxacin and disinfectants such as the quaternary ammonium compound benzalkonium chloride (BC), extensively used in the food processing industry 8 (146,151).…”

“…Even though multi-resistant strains are not frequently isolated, evidence of their presence is available (204). Given the current wide use of antibiotics in food production and clinics, isolation of L. monocytogenes with reduced antibiotic susceptibility is expected to grow.Ever since the first antibiotic-resistant strain was described in France in1988 (176) Antibiotic resistance in L. monocytogenes is mostly due three mobile genetic elements: selftransferable plasmids, mobilizable plasmids, and conjugative transposons (37,40,97,176,177).Efflux pumps have also been reported to be present in Listeria (86). …”

“…Although the occurrence of antibiotic resistance in L. monocytogenesis is still low, its presence in food, environment, and clinical settings are well documented (38,39,48,97,153,176,177,225). This pathogen is still highly susceptible to a wide range of antibiotics, including β-lactams (e.g.…”

“…Ever since the first antibiotic-resistant strain was described in France in1988 (176) Antibiotic resistance in L. monocytogenes is mostly due three mobile genetic elements: selftransferable plasmids, mobilizable plasmids, and conjugative transposons (37,40,97,176,177).…”