A total of 226 chicken samples (carcasses, legs, wings, necks and breasts) were obtained (73 in 1993 and 153 in 2006) from 10 retail outlets in North-Western Spain and screened for the presence of ...Salmonella. Isolates were subjected to serotyping, phage typing (Salmonella Enteritidis and Salmonella Typhimurium) and antimicrobial susceptibility testing (15 antimicrobials; disk diffusion method). Salmonella was detected in 40 (55%) samples in 1993 and 19 (12.4%) in 2006 (P<0.001). The serotypes (S. Enteritidis, Salmonella Poona, Salmonella Infantis, Salmonella Newport and S. Typhimurium) and phage types (1, 4, 14b and 35 in the case of S. Enteritidis and 193 for S. Typhimurium) detected are among the main types responsible for human salmonellosis in Spain. All strains were multi-resistant (resistant to 3–13 antimicrobials). The average number of resistances per strain increased (P<0.05) from 3.98 in 1993 to 5.00 in 2006. An increase in the incidence of resistance was observed between 1993 and 2006 for cephalothin (P<0.01), enrofloxacin (P<0.001) and tetracycline (P<0.01). The decreases in the prevalence of Salmonella between 1993 and 2006 suggest that the mandatory measures introduced over the last decade in the European Union to reduce the incidence of Salmonella in poultry have apparently been successful. However, the increase in antibiotic resistance rates is of concern and constitutes a threat to public health. Because the data in this study demonstrated that chicken in North-Western Spain is a potential source of antibiotic-resistant Salmonella strains, the need of consumer education on good sanitary practices is highlighted.
► The prevalence and antibiotic susceptibility of Salmonella on poultry were assessed. ► Data obtained in 1993 and 2006 from the same retail outlets in Spain were compared. ► A decrease in the prevalence (55.0% in 1993 and 12.4% in 2006) was observed over time. ► The serotypes and phage types detected are a frequent cause of human disease in Spain. ► The mean number of resistances per strain increased from 3.98 in 1993 to 5.00 in 2006.
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Cell-autonomous defense mechanisms are potent strategies that protect individual cells against intracellular pathogens. The Rab-family GTPase Rab32 was previously shown to restrict the intracellular ...human pathogen Salmonella Typhi, but its potential broader role in antimicrobial defense remains unknown. We show that Rab32 represents a general cell-autonomous, antimicrobial defense that is counteracted by two Salmonella effectors. Mice lacking Rab-32 or its nucleotide exchange factor BLOC-3 are permissive to S. Typhi infection and exhibit increased susceptibility to S. Typhimurium. S. Typhimurium counters this defense pathway by delivering two type III secretion effectors, SopD2, a Rab32 GAP, and GtgE, a specific Rab32 protease. An S. Typhimurium mutant strain lacking these two effectors exhibits markedly reduced virulence, which is fully restored in BLOC-3-deficient mice. These results demonstrate that a cell-autonomous, Rab32-dependent host defense pathway plays a central role in the defense against vacuolar pathogens and describe a mechanism evolved by a bacterial pathogen to counter it.
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•A Rab32-dependent mechanism of defense restricts the replication of Salmonella•Salmonella counters this host defense pathway with the effectors SopD2 and GtgE•SopD2 is a GAP and GtgE a protease, which both target Rab32•A mutant lacking these effectors exhibits drastic virulence reduction
Microbial pathogens have evolved mechanisms to counter host defense pathways that limit their replication. Spanò et al. show that a cell-autonomous, Rab32-dependent mechanism of defense restricts the replication of the intracellular pathogen Salmonella, which counters it by delivering a GAP and protease that target this Rab GTPase.
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Salmonella enterica serotype Dublin is a cattle-adapted bacterium that typically causes bloodstream infections in humans. To summarize demographic, clinical, and antimicrobial drug resistance ...characteristics of human infections with this organism in the United States, we analyzed data for 1968-2013 from 5 US surveillance systems. During this period, the incidence rate for infection with Salmonella Dublin increased more than that for infection with other Salmonella. Data from 1 system (FoodNet) showed that a higher percentage of persons with Salmonella Dublin infection were hospitalized and died during 2005-2013 (78% hospitalized, 4.2% died) than during 1996-2004 (68% hospitalized, 2.7% died). Susceptibility data showed that a higher percentage of isolates were resistant to >7 classes of antimicrobial drugs during 2005-2013 (50.8%) than during 1996-2004 (2.4%).
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It has been 30 years since the initial emergence and subsequent rapid global spread of multidrug-resistant Salmonella entericaserovar Typhimurium DT104 (MDR DT104). Nonetheless, its origin and ...transmission route have never been revealed. We used whole-genome sequencing (WGS) and temporally structured sequence analysis within a Bayesian framework to reconstruct temporal and spatial phylogenetic trees and estimate the rates of mutation and divergence times of 315S Typhimurium DT104 isolates sampled from 1969 to 2012 from 21 countries on six continents. DT104 was estimated to have emerged initially as antimicrobial susceptible in ∼1948 (95% credible interval CI, 1934 to 1962) and later became MDR DT104 in ∼1972 (95% CI, 1972 to 1988) through horizontal transfer of the 13-kb Salmonella genomic island 1 (SGI1) MDR region into susceptible strains already containing SGI1. This was followed by multiple transmission events, initially from central Europe and later between several European countries. An independent transmission to the United States and another to Japan occurred, and from there MDR DT104 was probably transmitted to Taiwan and Canada. An independent acquisition of resistance genes took place in Thailand in ∼1975 (95% CI, 1975 to 1990). In Denmark, WGS analysis provided evidence for transmission of the organism between herds of animals. Interestingly, the demographic history of Danish MDR DT104 provided evidence for the success of the program to eradicate Salmonellafrom pig herds in Denmark from 1996 to 2000. The results from this study refute several hypotheses on the evolution of DT104 and suggest that WGS may be useful in monitoring emerging clones and devising strategies for prevention of Salmonella infections.
Salmonellosis is a worldwide health problem; Salmonella infections are the second leading cause of bacterial foodborne illness in the United States. Approximately 95% of cases of human salmonellosis ...are associated with the consumption of contaminated products such as meat, poultry, eggs, milk, seafood, and fresh produce. Salmonella can cause a number of different disease syndromes including gastroenteritis, bacteremia, and typhoid fever, with the most common being gastroenteritis, which is often characterized by abdominal pain, nausea, vomiting, diarrhea, and headache. Typically the disease is self-limiting; however, with more severe manifestations such as bacteremia, antimicrobial therapy is often administered to treat the infection. Currently, there are over 2,500 identified serotypes of SALMONELLA: A smaller number of these serotypes are significantly associated with animal and human disease including Typhimurium, Enteritidis, Newport, Heidelberg, and Montevideo. Increasingly, isolates from these serotypes are being detected that demonstrate resistance to multiple antimicrobial agents, including third-generation cephalosporins, which are recommended for the treatment of severe infections. Many of the genes that encode resistance are located on transmissible elements such as plasmids that allow for potential transfer of resistance among strains. Plasmids are also known to harbor virulence factors that contribute to Salmonella pathogenicity. Several serotypes of medical importance, including Typhimurium, Enteritidis, Newport, Dublin, and Choleraesuis, are known to harbor virulence plasmids containing genes that code for fimbriae, serum resistance, and other factors. Additionally, many Salmonella contain pathogenicity islands scattered throughout their genomes that encode factors essential for bacterial adhesion, invasion, and infection. Salmonella have evolved several virulence and antimicrobial resistance mechanisms that allow for continued challenges to our public health infrastructure.
Conventional wisdom holds that microbes support their growth in vertebrate hosts by exploiting a large variety of nutrients. We show here that use of a specific nutrient (ethanolamine) confers a ...marked growth advantage on Salmonella enterica serovar Typhimurium (S. Typhimurium) in the lumen of the inflamed intestine. In the anaerobic environment of the gut, ethanolamine supports little or no growth by fermentation. However, S. Typhimurium is able to use this carbon source by inducing the gut to produce a respiratory electron acceptor (tetrathionate), which supports anaerobic growth on ethanolamine. The gut normally converts ambient hydrogen sulfide to thiosulfate, which it then oxidizes further to tetrathionate during inflammation. Evidence is provided that S. Typhimurium's growth advantage in an inflamed gut is because of its ability to respire ethanolamine, which is released from host tissue, but is not utilizable by competing bacteria. By inducing intestinal inflammation, S. Typhimurium sidesteps nutritional competition and gains the ability to use an abundant simple substrate, ethanolamine, which is provided by the host.
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Background. This study reports the microbiological landscape of Salmonella Typhi and invasive nontyphoidal Salmonella (iNTS) in the Democratic Republic of the Congo (DRC). Methods. Blood cultures ...obtained from hospital-admitted patients suspected of bloodstream infection (BSI) in 4 of 11 provinces in DRC (Kinshasa, Bas-Congo, Equateur, and Orientale) were processed. Sampling had started in 2007; the results for the period 2011–2014 are reported. Results. Salmonella Typhi and iNTS were cultured from 194 (1.4%) and 840 (5.9%), respectively, of 14 110 BSI episodes and ranked first among BSI pathogens in adults (65/300 21.7%) and children (783/1901 41.2%), respectively. A total of 948 of 1034 (91.7%) isolates were available for analysis (164 Salmonella Typhi and 784 iNTS). Salmonella Typhimurium and Salmonella Enteritidis represented 386 (49.2%) and 391 (49.9%), respectively, of iNTS isolates, fluctuating over time and geography and increasing during the rainy season. Adults accounted for <5% of iNTS BSI episodes. Children <5 years accounted for 20.3% of Salmonella Typhi BSI episodes. Among Salmonella Typhi, rates of multidrug resistance and decreased ciprofloxacin susceptibility (DCS) were 37.8% and 37.2%, respectively, and 18.3% displayed combined multidrug resistance and DCS; rates of azithromycin and ceftriaxone resistance were 0.6% and absent, respectively. Among NTS isolates, ≥80% (79.7% of Salmonella Enteritidis and 90.2% of Salmonella Typhimurium isolates) showed multidrug resistance, and <2.5% showed DCS. Combined extended-spectrum β-lactamase production (blaTEM-1 gene) and azithromycin resistance was noted in 12.7% of Salmonella Typhimurium isolates, appearing in Bas-Congo from 2013 onward. Conclusions. Salmonella Typhi and NTS are major causes of BSI in DRC; their antimicrobial resistance is increasing.
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Salmonella enterica subsp. enterica contains more than 2,600 serovars of which four are of major medical relevance for humans. While the typhoidal serovars (Typhi and Paratyphi A) are ...human-restricted and cause enteric fever, non-typhoidal Salmonella serovars (Typhimurium and Enteritidis) have a broad host range and predominantly cause gastroenteritis.
We compared the core proteomes of Salmonella Typhi, Paratyphi A, Typhimurium and Enteritidis using contemporary proteomics. For each serovar, five clinical isolates (covering different geographical origins) and one reference strain were grown in vitro to the exponential phase. Levels of orthologous proteins quantified in all four serovars and within the typhoidal and non-typhoidal groups were compared and subjected to gene ontology term enrichment and inferred regulatory interactions. Differential expression of the core proteomes of the typhoidal serovars appears mainly related to cell surface components and, for the non-typhoidal serovars, to pathogenicity.
Our comparative proteome analysis indicated differences in the expression of surface proteins between Salmonella Typhi and Paratyphi A, and in pathogenesis-related proteins between Salmonella Typhimurium and Enteritidis. Our findings may guide future development of novel diagnostics and vaccines, as well as understanding of disease progression.
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Invasive Salmonellosis in Kilifi, Kenya Muthumbi, Esther; Morpeth, Susan C.; Ooko, Michael ...
Clinical infectious diseases,
11/2015, Volume:
61, Issue:
suppl 4
Journal Article
Peer reviewed
Open access
Background. Invasive salmonelloses are a major cause of morbidity and mortality in Africa, but the incidence and case fatality of each disease vary markedly by region. We aimed to describe the ...incidence, clinical characteristics, and antimicrobial susceptibility patterns of invasive salmonelloses among children and adults in Kilifi, Kenya. Methods. We analyzed integrated clinical and laboratory records for patients presenting to the Kilifi County Hospital between 1998 and 2014. We calculated incidence, and summarized clinical features and multidrug resistance. Results. Nontyphoidal Salmonella (NTS) accounted for 10.8% and 5.8% of bacteremia cases in children and adults, respectively, while Salmonella Typhi accounted for 0.5% and 2.1%, respectively. Among 351 NTS isolates serotyped, 160 (45.6%) were Salmonella Enteritidis and 152 (43.3%) were Salmonella Typhimurium. The incidence of NTS in children aged <5 years was 36.6 per 100 000 person-years, being highest in infants aged <7 days (174/100 000 person-years). The overall incidence of NTS in children varied markedly by location and declined significantly during the study period; the pattern of dominance of the NTS serotypes also shifted from Salmonella Enteritidis to Salmonella Typhimurium. Risk factors for invasive NTS disease were human immunodeficiency virus infection, malaria, and malnutrition; the case fatality ratio was 22.1% (71/321) in children aged <5 years and 36.7% (11/30) in adults. Multidrug resistance was present in 23.9% (84/351) of NTS isolates and 46.2% (12/26) of Salmonella Typhi isolates. Conclusions. In Kilifi, the incidence of invasive NTS was high, especially among newborn infants, but typhoid fever was uncommon. NTS remains an important cause of bacteremia in children <5 years of age.
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Salmonella Typhimurium and Enteritidis are major causes of bloodstream infection in children in sub-Saharan Africa. This study assessed evidence for their zoonotic versus human reservoir.
Index ...patients were children with blood culture confirmed Salmonella infection recruited during a microbiological surveillance study in Nanoro, rural Burkina between May 2013 and August 2014. After consent, their households were visited. Stool from household members and livestock (pooled samples per species) as well as drinking water were cultured for Salmonella. Isolates with identical serotype obtained from index patient and any household sample were defined as "paired isolates" and assessed for genetic relatedness by multilocus variable number tandem-repeat analysis (MLVA) and whole-genome sequencing (WGS).
Twenty-nine households were visited for 32/42 (76.2%) eligible index patients: two households comprised two index patients each, and in a third household the index patient had a recurrent infection. Among the 32 index patients, serotypes were Salmonella Typhimurium (n = 26), Salmonella Enteritidis (n = 5) and Salmonella Freetown (n = 1). All Typhimurium isolates were sequence type (ST)313. Median delay between blood culture sampling and household visits was 13 days (range 6-26). Salmonella was obtained from 16/186 (8.6%) livestock samples (13 serotypes) and 18/290 (6.2%) household members (9 serotypes). None of the water samples yielded Salmonella. Paired Salmonella Typhimurium isolates were obtained from three households representing four index patients. MLVA types were identical in two pairs and similar in the third (consisting of two index patients and one household member). WGS showed a strong genetic relatedness with 0 to 2 core genome SNPs difference between pairs on a household level. Livestock samples did not yield any Salmonella Typhimurium or Salmonella Enteritidis, and the latter was exclusively obtained from blood culture. Other serotypes shared by human and/or livestock carriers in the same household were Salmonella Derby, Drac, Tennessee and Muenster.
The current study provides further evidence of a human reservoir for invasive non-Typhoidal Salmonella (iNTS) in sub-Saharan Africa.
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