Incidence of Antibiotic Resistance in Listeria Species

Abstract

To define the prevalence of antibiotic resistance in Listeria species pathogenic for humans and animals, 1100 isolates (60 from cases of listeriosis and 1040 from food and environment) collected worldwide were screened. Of the 61 tetracycline- and minocycline-resistant strains (37 Listeria monocytogenes), 57 harbored tet(M); 4 non-L. monocytogenes isolates contained tet(S). One Listeria innocua isolate was also resistant to streptomycin and contained the tet(M) and aad6 genes. An L. monocytogenes isolate was trimethoprim-resistant, a characteristic not reported previously in Listeria species, because of the presence of a yet-uncharacterized gene. Three clinical isolates of L. monocytogenes were resistant to low levels of streptomycin. Since the tet(M), tet(S), and aad6 genes are common in enterococci and streptococci, these data suggest transfer from the latter to Listeria species. Uniform susceptibility to tetracycline, minocycline, trimethoprim, and streptomycin cannot be assumed any longer for Listeria species.

Antimicrobial susceptibilities of Listeria monocytogenes human strains isolated from 1970 to 2008 in Brazil

“…The same result was obtained by LemesMarques et al 19 , although reports in the literature demonstrate resistance to trimethoprim 25 , as well as the combination of trimethoprim-sulfamethoxazole 26,27 . MICs with values up to 2μg/ ml reinforce the need for microbiological surveillance.…”

“…No resistance to the association of trimethoprim-sulfamethoxazole was observed, which is important considering its nomination as an alternative in the treatment of listeriosis, primarily in patients with intolerance to penicillin 5,24 . The same result was obtained by LemesMarques et al 19 , although reports in the literature demonstrate resistance to trimethoprim 25 , as well as the combination of trimethoprim-sulfamethoxazole 26,27 .…”

“…Among the 13 serotypes of L. monocytogenes in the literature, serovar 4b is primarily responsible for most of the outbreaks in humans 5,13 while the serovar 1/2a prevails in food and in some regions of the world where it is more common in human cases [14][15][16] .…”

“…It appears that virtually the same profile has been identified over the years and in different countries. In relation to tetracycline, this research highlighted the extreme sensitivity of the 68 strains to this drug, contrasting with the emergence of clinical strains resistant to tetracycline, related to the gene tetM 5,22,23 .…”

“…gentamicin), and other second-choice antimicrobials represented by chloramphenicol, erythromycin, tetracycline and rifampicin [4][5][6] . However, clinical strains resistant to chloramphenicol, erythromycin, streptomycin, tetracycline, vancomycin and trimethoprim have been recently described 4 .…”