[Characterization of Salmonella Heidelberg strains isolated in Chile]. / Caracterización de cepas clínicas y ambientales de Salmonella enterica subsp. enterica serovar Heidelberg aisladas en Chile.

BACKGROUND: Salmonella Heidelberg (S. Heidelberg) causes gastroenteritis and sometimes bacteremia and endocarditis. In other countries, this serovar has multidrug resistance including extended-spectrum ß-lactamases (ESBLs) and AmpC (ß-lactamases (AmpC), associated with the blaCMY-2 gene. In Chile, an outbreak by S. Heidelberg occurred in 2011, the phenotypic and genetic characteristics of Chilean strains are unknown. AIM: To determine the antimicrobial susceptibility, presence of plasmids and virulence factor genes in S. Heidelberg strains isolated in Chile over the period 2006-2011. MATERIAL AND METHODS: In sixty-one S. Heidelberg clinical and environmental strains collected by the Public Health Institute in Chile during 2006-2011, antimicrobial susceptibility, plasmids and virulence factor genes (invA, sifA, pefA, agfA, lpfA and, stkD) were studied. RESULTS: S. Heidelberg had a high susceptibility to sulfamethoxazole-trimethoprim, gentamicin, ceftriaxone, ceftiofur, chloramphenicol, amoxicillin-clavulanic acid and ampicillin. However, 52% had decreased susceptibility to ciprofloxacin and 33% resistance to tetracycline. ESBLs were detected in three strains isolated from blood cultures, environment and human feces. The latter strain was positive for AmpC and blaCMY-2 gene. Fifty three of 61 strains showed one to seven plasmids of 0.8 to approximately 30 kb. Most plasmids were small with sizes between 0.8 and 2 kb. All isolates were positive for all genes except pefA. CONCLUSIONS: S. Heidelberg isolated from Chilean samples was susceptible to first-line antimicrobials, except tetracycline and ciprofloxacin. The emergence of strains with ESBLs and AmpC should be a warning. The strains were homogeneous for virulence genes, but heterogeneous in their plasmids.

Caracterización de cepas clínicas y ambientales de Salmonella enterica subsp. enterica serovar Heidelberg aisladas en Chile / Characterization of Salmonella Heidelberg strains isolated in Chile

Background: Salmonella Heidelberg (S. Heidelberg) causes gastroenteritis and sometimes bacteremia and endocarditis. In other countries, this serovar has multidrug resistance including extended-spectrum β-lactamases (ESBLs) and AmpC (β-lactamases (AmpC), associated with the blaCMY-2 gene. In Chile, an outbreak by S. Heidelberg occurred in 2011, the phenotypic and genetic characteristics of Chilean strains are unknown. Aim: To determine the antimicrobial susceptibility, presence of plasmids and virulence factor genes in S. Heidelberg strains isolated in Chile over the period 2006-2011. Material and Methods: In sixty-one S. Heidelberg clinical and environmental strains collected by the Public Health Institute in Chile during 2006-2011, antimicrobial susceptibility, plasmids and virulence factor genes (invA, sifA, pefA, agfA, lpfA and, stkD) were studied. Results: S. Heidelberg had a high susceptibility to sulfamethoxazole-trimethoprim, gentamicin, ceftriaxone, ceftiofur, chloramphenicol, amoxicillin-clavulanic acid and ampicillin. However, 52% had decreased susceptibility to ciprofloxacin and 33% resistance to tetracycline. ESBLs were detected in three strains isolated from blood cultures, environment and human feces. The latter strain was positive for AmpC and blaCMY-2 gene. Fifty three of 61 strains showed one to seven plasmids of 0.8 to approximately 30 kb. Most plasmids were small with sizes between 0.8 and 2 kb. All isolates were positive for all genes except pefA. Conclusions: S. Heidelberg isolated from Chilean samples was susceptible to first-line antimicrobials, except tetracycline and ciprofloxacin. The emergence of strains with ESBLs and AmpC should be a warning. The strains were homogeneous for virulence genes, but heterogeneous in their plasmids.

[Molecular subtyping of Salmonella enterica serotype Enteritidis in a post epidemic period]. / Subtipificación molecular de Salmonella entérica serotipo Enteritidis en el período post epidémico.

BACKGROUND: In the last two decades, Salmonella enterica serotype Enteritidis has become one of the main agents causing food borne diseases worldwide. This agent is transmitted mainly by contaminated meat and poultry. AIM: To determine the genetic subtypes of Salmonella enterica serotype Enteritidis, circulating in Chile between 2001 and 2003, a post epidemic period. MATERIAL AND METHODS: One hundred ninety three isolates coming from human samples, prepared foods and animal products for human consumption, were analyzed by pulsed field electrophoresis, using PulseNet standardized protocol. RESULTS: Thirteen subtypes of Salmonella enterica serotype Enteritidis were identified, that had between 0 and 13 bands. A predominant subtype was identified in 172 strains (88%) that came from human isolates, prepared foods and animal products for human consumption. Other four subtypes, found in prepared foods and animal products for human consumption, were also found in human isolates. Most subtypes were tightly interrelated Subtypes II, VIII and XI were also found in the 1994 epidemic. CONCLUSIONS: Subtyping of bacterial strains by pulsed field electrophoresis is useful for the surveillance of food borne diseases.

Reporte de cuatro casos clínicos de bacteriemia por Hafnia alvei en una unidad cardio-quirúrgica pediátrica / Report of four clinical cases of Hafnia alvei bacteremia in a pediatric cardiac surgery unit

Introduction: The gram-negative bacillus Hafnia alvei is the only species of the genus Hafnia, family Enterobacteriaceae. It occasionally behaves as an opportunistic pathogen in humans, causing intestinal and respiratory infection and sepsis. It rarely causes bacteremia, usually of unknown focus. Objective: To describe a nosocomial outbreak of four pediatric patients with bacteremia by Hafnia alvei. Methods: Descriptive study using clinical records of pediatric patients diagnosed with Hafnia alvei bacteremia in a pediatric cardio surgical unit, in October 2008. Results: The attack rate was 4/8 (50 percent), lethality rate 2/4 (50 percent) and mortality 2/8 (25 percent). The microbiological study and pulsed-field gel electrophoresis confirmed the same clonal bacterial strain. Discussion: The source of bacteremia was identified only in two patients and was associated with central venous catheters. The other two cases had no known infectious source. Epidemiological surveillance of emerging agents must be maintained.

Introducción: Hajhia alvei, bacilo Gram negativo, constituye la única especie del género Hajhia, familia Enterobacteriaceae. En el humano se comporta ocasionalmente como oportunista produciendo infección intestinal, respiratoria y sepsis. Es causa infrecuente de bacteriemias, generalmente de foco infeccioso desconocido. Objetivo: Describir un brote intrahospitalario de cuatro pacientes pediátricos con bacteriemias por Hajhia alvei. Método: Estudio descriptivo retrospectivo de los registros clínicos de cuatro pacientes pediátricos con diagnóstico de bacte-riemia por Hajhia alvei en una unidad cardioquirúrgica pediátrica identificados en octubre del 2008. Resultados: La tasa de ataque fue 4/8 (50 por ciento), tasa de letalidad 2/4 (50 por ciento) y de mortalidad de 2/8 (25 por ciento). El estudio micro-biológico y la electroforesis de campo pulsado confirman la misma cepa bacteriana clonal. Discusión: Se identificó el origen de la bacteriemia sólo en dos pacientes asociado a catéter venoso central. Los otros dos casos no tuvieron foco infeccioso conocido. Se debe mantener vigilancia epidemiológica de agentes emergentes.

Subtipificación molecular de Salmonella entérica serotipo Enteritidis en el período post epidémico / Molecular subtyping of Salmonella enterica serotype Enteritidis in a post epidemic period

Background: In the last two decades, Salmonella enterica serotype Enteritidis has become one of the main agents causing food borne diseases worldwide. This agent is transmitted mainly by contaminated meat and poultry. Aim: To determine the genetic subtypes of Salmonella enterica serotype Enteritidis, circulating in Chile between 2001 and 2003, a post epidemc period. Material and methods: One hundred ninety three isolates coming from human samples, prepared foods and animal products for human consumption, were analyzed bypulsed field electrophoresis, using PulseNet standardized protocol. Results: Thirteen subtypes of Salmonella enterica serotype Enteritidis were identified, that had between 0 and 13 bands. A predominant subtype was identified in 172 strains (88%) that carne from human isolates, prepared foods and animal producís for human consumption. Other four subtypes, found in prepared foods and animal products for human consumption, were also found in human isolales. Most subtypes were lighlly inlerrelaled Subtypes II, VIII and XI were also found in the 1994 epidemic. Conclusions: Subtyping of baclerial strains by pulsed field electrophoresis is useful for the surveillance of food borne diseases.

Cambios epidemiológicos de las salmonelosis en Chile: desde salmonella typhi a salmonella enteritidis / Changes in epidemiological patterns of salmonellosis in Chile: since salmonella typhi to salmonella enteritidis

Chile ha experimentado un cambio epidemiológico en la última década con la desaparición progresiva de la fiebre tifoidea causada mayoritariamente por Salmonella typhi y la emergencia epidémica de Salmonella enteritidis, un agente de diarrea sin tratamiento específico eficaz y ligado estrechamente a productos avícolas contaminados e inadecuadamente preparados. La fiebre tifoidea ha disminuido su importancia debido al desarrollo humano experimentado en Chile que ha significado un alto grado de cobertura de agua potable y de manejo de excretas, en conjunto con un mayor nivel de educación, factores que limitan la contaminación del ambiente por este agente y la adquisición de él por huéspedes susceptibles. A pesar de este notable avance, un nuevo serotipo de salmonela ha irrumpido en Chile, denominado enteritidis, que ha logrado aprovechar el nuevo escenario logrado con la industrialización avícola donde miles de aves ahora conviven en pequeños espacios facilitando la infección cruzada entre ellas. La contaminación intermitente de huevos por vía transovárica o superficial permite la llegada de este agente en forma errática pero persistente al ser humano. Este nuevo escenario y la ausencia de un tratamiento antimicrobiano eficaz para este agente, obligan a que nuestro país adopte nuevas estrategias de prevención que involucran a productores, distribuidores y consumidores de productos avícolas

Detección de salmonella enteritidis en muestras de productos avícolas de consumo humano en la Región Metropolitana / Detection of salmonella enteritidis in samples of poultry products for human consumption in the chilean metropolitan area

Background: Salmonella enteritidis (SE) is a frequent cause of diarrhea, and is transmitted mainly by SE contaminated eggs or poultry meat. The frequency of SE contaminated eggs or chicken meat and the risk for acquiring this pathogen is unknown in Chile. Aim: To measure SE contamination in eggs poultry meat and entrails offered in retail markets in the Metropolitan Area during two consecutive years (1998-1999). Material and methods: Samples were placed in sterile bags and transported to the laboratory before 4 hours at 4­C. Microbiologic detection was done using a standard procedure and an immunodetection assay. Results: SE was found in one of 1081 egg samples (0.09 percent). The contaminated sample was offered in a supermarket under their own commercial name. Six percent of 1154 poultry meat samples were contaminated by SE and 2.3 percent by other Salmonella serotypes. Entrails had even higher rates with 10.2 percent of 370 samples harboring SE and 2,7 percent other serotypes. Total Salmonella sp. isolates and SE isolates declined during 1999. Nine SE phagotypes were identified, predominating types 4 and 7. Conclusions: Eggs and other avian products are contaminated by different SE phagotypes and other Salmonella serotypes, implicating a risk for the consumers

Salmonella enteritidis: un patógeno emergente en Chile / Salmonella enteritidis: an emergent pathogen in Chile

Materials and methods: Cases of clinical infections by Salmonella enteritidis were recorder from bacteriological and demographic notifications obtained at The National Reference Laboratory for Enterobacteria. Infection rates were calculated using the total Chilean population and the population of the different Health Services along the country. Results: Until 1993, 13,57 Salmonella enteritidis strains per year were received at the Reference Laboratory. The figures increased to 478 and 432 in 1994 and 1995, respectively. National rates were 3,41 and 3.04 notifications/100.000 inhabitans in 1994 and 1995 respectively. Northern regions were the most affected and 90 percent of observed cases during 1994 came from Arica and Antofagasta. At the present time, 20 percent of cases are observed in Santiago, located in the mid-portion of the country. The outbreak has mainly affected children and young adults (yo percent of cases). Strains have been isolated from stool cultures, suggestig gastrointestinal infections as the main clinical presentation. More than 98 percent of strains are susceptible to chloramphenicol, ampicillin, tetracycline, sulfa-trimetroprim, cefotaxime or ciprofloxacin. Conclusions: The obtained data clearly indicate the existence of an epidemic outbreak of Salmonella enteritidis infections, with a geographic progression from North to South