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

• Published in: Revista da Sociedade Brasileira de Medicina Tropical Vol. 44; no. 2; pp. 173 - 176
• Main Authors: Reis, Cristhiane Moura Falavina dos, Barbosa, André Victor, Rusak, Leonardo Alves, Vallim, Deyse Christina, Hofer, Ernesto
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Medicina Tropical 01-03-2011; Sociedade Brasileira de Medicina Tropical - SBMT; Sociedade Brasileira de Medicina Tropical (SBMT)
• Subjects: Anti-Bacterial Agents - pharmacology; Antimicrobial agents; Brazil; DNA, Bacterial - analysis; Foodborne diseases; Genotype; Humans; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - genetics; Listeria monocytogenes - isolation & purification; Listeriose; Microbial Sensitivity Tests; Polymerase Chain Reaction; Susceptibilidade antimicrobiana; TROPICAL MEDICINE; Brazil; Listeria monocytogenes; Listeriosis; Susceptibilidade antimicrobiana; Listeriose; Antimicrobial susceptibilities
• ISSN: 0037-8682; 1678-9849; 1678-9849
• DOI: 10.1590/S0037-86822011005000019

Listeria monocytogenes is the causative agent of listeriosis, a foodborne illness that affects mainly pregnant women, the elderly and immunocompromised patients. The primary treatment is a combination of ampicillin with an aminoglycoside, in addition to a second-choice drug represented by chloramphenicol, erythromycin, tetracycline and rifampicin. The aim of this study was to analyze the antimicrobial susceptibility profile of strains isolated from human sources in the last four decades.
Sixty-eight strains were selected from the culture collection of the Laboratory of Bacterial Zoonoses/LABZOO/FIOCRUZ isolated in different regions of Brazil from 1970 to 2008 and primarily isolated from cerebrospinal fluid and blood culture. Susceptibility tests to antimicrobials drugs were evaluated using the criteria established by Soussy using the Kirby-Bauer method and E-Test strips were used to determine the minimum inhibitory concentration (MIC).
Among the strains tested, serovar L4b (60.3%) was the most prevalent, followed by serovar 1/2a (20.6%), 1/2b (13.2%) and the more uncommon serovars 1/2c, 3b and 4ab (5.9%). All strains were susceptible to ampicillin, cephalothin, erythromycin, gentamicin, teicoplanin and vancomycin. Only one strain (1.5%) showed resistance to rifampin, and two (3%) were resistant to trimethoprim-sulfamethoxazole. MICs with values up to 2 μg/ml reinforce the need for microbiological surveillance.
The study demonstrated low prevalence of strains resistant to the antimicrobial drugs indicated in the treatment of human listeriosis. Monitoring antimicrobial resistance profile is still very important to determine adequate treatment, especially in immunocompromised patients.