Molecular Subtyping ofSalmonella entericaSerovar Typhi Isolates from Colombia and Argentina

Abstract

Salmonella Typhi is the etiological agent of typhoid fever with 16 million annual cases estimated worldwide. In Colombia and Argentina it is a notifiable disease but many cases have only a clinical diagnosis. Molecular subtyping of S. Typhi is necessary to complement epidemiologic analysis of typhoid fever. The aims of this study were to determine the genetic relationships between the strains circulating in both countries and to evaluate possible variations in the distribution of 12 virulence genes. A total of 136 isolates were analyzed by pulsed-field gel electrophoresis (PFGE) with XbaI following PulseNet protocols and analysis guidelines. Eighty-three different PFGE patterns were identified, showing high diversity among the strains from both countries. Three outbreaks, two in Colombia and one in Argentina, were caused by strains of different PFGE types. In Colombia, two PFGE patterns were found predominantly, which included 36.6% of the isolates from that country. No association was found between the PFGE patterns and the year or place of isolation of the strains, the age of the patients or type of sample. However, several clusters were detected, which included isolates recovered predominantly either from Colombia or Argentina. Most of the strains (97%) exhibited a single virulence profile, suggesting that the pathogenicity markers analyzed are of limited value for strain discrimination and do not correlate with the origin of the isolates (intestinal vs. extra-intestinal). Since the creation of PulseNet Latin America, this was the first international study conducted in South America. The PFGE types identified were incorporated into the Regional S. Typhi PulseNet Database and are now available for comparison with those of strains isolated in other regions. This information will be used for active surveillance, future studies, and outbreak investigations.

Building PulseNet Latin America and Caribbean Salmonella regional database: First conclusions of genetic subtypes of S. Typhi, S. Typhimurium and S. Enteritidis circulating in six countries of the region

“…On the other hand, S. enterica ser. Typhi (3.9%, with variations between the countries, ranging from no isolates reported to 10.4% within the country) is also considered relevant, because of its role as an etiological agent of typhoid fever (Salve et al, 2006). Over the last ten years, some studies have been conducted in South America to evaluate the genetic diversity of Salmonella spp.…”

“…Over the last ten years, some studies have been conducted in South America to evaluate the genetic diversity of Salmonella spp. isolates of these serovars, like those focused on S. Enteritidis in Brazil, Chile and neighboring countries (Fernandez et al, 2003;De Oliveira, Pasqualotto, da Silva, and Tondo (2010)), S. Typhi in Colombia and Argentina (Salve et al, 2006) and S. Typhimurium in Colombia (Muñoz, Realpe, Castañeda, & Agudelo, 2006). However, these studies were mainly directed to the analysis of strains from one or few countries and did not provide a regional platform for future comparisons and surveillance.…”

Intermediate Susceptibility to Ciprofloxacin among Salmonella enterica Serovar Typhi Isolates in Lima, Peru

“…Of note, disk diffusion was the method used in both studies. Since MIC values were not determined, it is possible that isolates with ISC were missed (10,11).…”

Multidrug-ResistantSalmonella entericaSerovar Paratyphi A Harbors IncHI1 Plasmids Similar to Those Found in Serovar Typhi

“…While endemic enteric fever has been eliminated from most developed nations by improved sanitation (6), enteric fever is still a significant health threat in Southeast Asia, the Indian subcontinent, Africa, and, to a lesser extent, South America (16,34,38,40). Historically, enteric fever has been a target of control programs and vaccines, but antibiotic treatment remains a central pillar of control (13).…”