Molecular Epidemiological and Antibiotic Susceptibility Characterization of Brucella Isolates from Humans in Sicily, Italy

Abstract

Brucellosis is a serious problem in Sicily. Brucella melitensis was identified as the species most frequently isolated in humans in Italy. No data, however, are available about the molecular epidemiological characterization of Brucella isolates from humans. We have conducted this study to molecularly characterize clinical isolates of Brucella spp. and to evaluate their antimicrobial susceptibilities. Twenty Brucella isolates were studied. Differential growth characteristics and DNA polymorphisms such as the restriction patterns of the PCR-amplified omp2a and omp2b genes, rpoB nucleotide sequencing, and multiple-locus variable-number tandem repeat analysis of 16 loci (MLVA-16) were used to characterize the strains. In vitro antibiotic susceptibility was determined by the E-test method on two different agar media, and the results were compared. All isolates were identified as B. melitensis biovar 3. rpoB nucleotide sequence analysis allowed the identification of two different genotypes of B. melitensis biovar 3. On the other hand, the MLVA-16 typing assay recognized 17 distinct genotypes. All isolates were sensitive to all tested antibiotics (rifampin, doxycycline, ciprofloxacin, ceftriaxone, and trimethoprim-sulfamethoxazole), and the Mueller-Hinton agar plate is recommended for antibiotic susceptibility testing by the E-test method. Our findings identify B. melitensis biovar 3 as the etiological agent isolated in Sicily and encourage the use of both molecular methods, and in particular of the MLVA-16 assay, in epidemiological trace-back analysis. This study represents the first epidemiological data from molecular typing of Brucella strains circulating in Italy and, in particular, in eastern Sicily.Brucellosis is an important health problem affecting animals and humans in many countries in the world and especially in the Mediterranean areas. Brucella infections may cause tremendous economic losses through reproductive failure in animals. The disease is transmitted by humans through the consumption of contaminated foods or by direct/indirect contact with infected animals. Brucella melitensis is the most important zoonotic agent, followed by Brucella abortus and Brucella suis.

Multiple-Locus Variable-Number Tandem-Repeat Analysis Genotyping of Human Brucella Isolates from Turkey

“…3 was the biovar most frequently isolated in humans (4-6, 8, 12, 13, 22). The data obtained in Turkey are consistent with the results obtained in the Mediterranean region (1,16,21,26). These results reveal that human brucellosis in Turkey seems to be related more to ovicaprine than to cattle infection, which may be partly attributed to the virulence of the organism.…”

“…The MLVA-16 Orsay assay has been shown to be an appropriate method for species identification in the Brucella genus, for discriminating isolates originating from restricted geographic sources at the subspecies level, and for trace-back analyses (1,14). This method has been reported to be highly discriminatory to distinguish strains within a local outbreak, and to some extent phylogenetically relevant (1,11,14,16,18,23) and typing data from several hundred isolates can be queried and accessed via the Internet (http://mlva.u-psud.fr). The genetic diversity of Brucella strains isolated from human and animal infection has not yet been investigated in Turkey.…”

Evaluation of a Multilocus Variable-Number Tandem-Repeat Analysis Scheme for Typing Human Brucella Isolates in a Region of Brucellosis Endemicity

“…The diversity of the panel 1 loci and most panel 2 loci in our series parallels that found in a study of 24 human B. melitensis isolates from Sicily in Italy (24). The two studies are comparable in that they focused on a restricted geographic area.…”

<i>In Vitro</i> Antimicrobial Susceptibility of <i>Brucella melitensis</i> Isolates from Sheep in an Area Endemic for Human Brucellosis in Turkey

“…Nevertheless, sporadic cases of antibiotic resistance have been reported [9,23]. In contrast to the other studies [2,9], in this study, B. melitensis isolates were highly resistant (46.3%) against TMP/SMZ, which is consistent with previous reports [4,19,25]. There may be a number of reasons why different results were obtained against TMP/SMZ.…”