Subspecies Enterica Research Articles

Genotyping results of Salmonella Infantis as a food poisoning agent in Turkey between 2013 and 2017

The aim of this study is to define the genotyping relationship between 31 Salmonella enterica subspecies enterica serovar Infantis (S. Infantis) strains, which were the most isolated and identified causes of food poisoning between 2013 and 2017 in Turkey. These isolated strains were studied with the DiversiLab System (repetitive sequence-based PCR; rep-PCR; bioMerieux, France) and traditional serotyping for the identification of S. Infantis was also carried out. Totally, 31 S. Infantis isolates were genotyped. DNA was extracted from each isolate using the Microbial DNA Isolation Kit as well as rep-PCR. The dendrogram shows the diversity of the observed samples contained in the library with 4 main clusters of S. Infantis (26 strains) being significantly different from each other with a similarity of more than 95% between strains. Furthermore, it was found that the cause of almost all of these cases originated from chicken or chicken-based products. Even though the isolated S. Infantis strains came from different geographical locations, after genotyping, their genetic profiles were found to be similar. This is the first retrospective study concerning the molecular characterization of S. Infantis isolates obtained from food poisoning cases between 2013 and 2017 in Turkey.

Typhoid and paratyphoid fever

Typhoid fever and paratyphoid fever are systemic infectious diseases of global significance caused by Salmonella enterica subspecies enterica Serovar Typhi (short name: Salmonella Typhi) or Serovar Paratyphi (short name: Salmonella Paratyphi). The course of these fecal-orally transmitted diseases is mainly characterized by a high fever. Left untreated, the course of typhoid fever can be severe and lethal. The infection is almost always acquired outside of Europe (mainly in India) and is notifiable in Germany, Austria and Switzerland. Paratyphoid is an attenuated disease of typhoid fever caused by Salmonella Paratyphi. Available vaccines only protect against Salmonella Typhi. Antibiotic resistance reflects the situation in endemic countries and shows a worrying increase of multi-drug resistant isolates. Currently, third-generation cephalosporins such as ceftriaxone are recommended as first-line therapy; if sensitive to quinolones, fluoroquinolones such as ciprofloxacin may continue to be administered. Crucial preventive measures for travelers to endemic regions include consistent water and food hygiene as well as vaccination, whereby only protection rates of 50-70 % are achieved by currently available vaccines. In the light of increasing multi-drug resistance, a more effective conjugate vaccine against Salmonella Typhi with cross-reactivity against Salmonella Paratyphi is needed more than ever.

Distinct but Intertwined Evolutionary Histories of Multiple Salmonella enterica Subspecies.

Salmonella is responsible for many nontyphoidal foodborne infections and enteric (typhoid) fever in humans. Of the two Salmonella species, Salmonella enterica is highly diverse and includes 10 known subspecies and approximately 2,600 serotypes. Understanding the evolutionary processes that generate the tremendous diversity in Salmonella is important in reducing and controlling the incidence of disease outbreaks and the emergence of virulent strains. In this study, we aim to elucidate the impact of homologous recombination in the diversification of S. enterica subspecies. Using a data set of previously published 926 Salmonella genomes representing the 10 S. enterica subspecies and Salmonella bongori, we calculated a genus-wide pan-genome composed of 84,041 genes and the S. enterica pan-genome of 81,371 genes. The size of the accessory genomes varies between 12,429 genes in S. enterica subsp. arizonae (subsp. IIIa) to 33,257 genes in S. enterica subsp. enterica (subsp. I). A total of 12,136 genes in the Salmonella pan-genome show evidence of recombination, representing 14.44% of the pan-genome. We identified genomic hot spots of recombination that include genes associated with flagellin and the synthesis of methionine and thiamine pyrophosphate, which are known to influence host adaptation and virulence. Last, we uncovered within-species heterogeneity in rates of recombination and preferential genetic exchange between certain donor and recipient strains. Frequent but biased recombination within a bacterial species may suggest that lineages vary in their response to environmental selection pressure. Certain lineages, such as the more uncommon non-enterica subspecies (non-S. enterica subsp. enterica), may also act as a major reservoir of genetic diversity for the wider population.IMPORTANCE S. enterica is a major foodborne pathogen, which can be transmitted via several distinct routes from animals and environmental sources to human hosts. Multiple subspecies and serotypes of S. enterica exhibit considerable differences in virulence, host specificity, and colonization. This study provides detailed insights into the dynamics of recombination and its contributions to S. enterica subspecies evolution. Widespread recombination within the species means that new adaptations arising in one lineage can be rapidly transferred to another lineage. We therefore predict that recombination has been an important factor in the emergence of several major disease-causing strains from diverse genomic backgrounds and their ability to adapt to disparate environments.

A rare isolate of Salmonella Bareilly from a case of pancreatic pseudocyst

Non-typhoidal Salmonella are important food-borne pathogens that are associated with gastroenteritis, bacteraemia and focal infections. Salmonella enterica subspecies enterica serovar bareilly has been implicated in gastroenteritis and nosocomial infections. There are not much literature available on the hepatobiliary involvement by S. bareilly. We report a case of acute pancreatitis with pseudocyst. S. bareilly was isolated from blood and pseudocyst aspirate.

Behavior of spoilage bacteria and Salmonella enterica subspecies enterica O:4,5 in vacuum-packaged beef during refrigeration

ABSTRACT: In this study, the kinetic parameters of mesophilic, psychrotrophic and lactic acid bacteria in vacuum-packed beef at 1 °C and 4 °C were estimated from experimental growth curves produced by samples stored during 21 and 60 days, respectively. In a separate experiment, the survival of multidrug resistant (MDR) Salmonella enterica O:4,5 at 1°C was also characterized. The shelf-life of vacuum-packed beef stored at 4 °C was estimated at 16.1 days (95% CI: 14.8 - 17.3 days), whereas at 1 °C it was longer than 21 days because the mesophiles count estimated towards the end of the experiment was 12.5 ln CFU.g-1 (95% CI: 11.8 - 13.3 ln CFU.g-1) which is lower than the shelf-life reference value. At 1 °C, inoculated Salmonella was reduced in 6.61 ln CFU.g-1 (2.87 log CFU.g-1). These results demonstrated the importance of establishing in legislation, especially in Brazil, standard values of deteriorating microorganisms in beef for maintaining product quality.

Molecular Typing of Different Salmonella Serotypes by Multiple-Locus Analysis of Tandem Repeats.

Salmonella enterica subspecies enterica causes salmonellosis in humans and animals and is an important cause of food infections worldwide. In recent years, the multiple-locus variable-number of tandem repeat (VNTR) analysis (MLVA), a fast molecular typing method with strong epidemiological discrimination, has facilitated the effective control of diverse infections. This study aimed at the typing of 28 human origined Salmonella enteritidis, Salmonella infantis, and Salmonella typhimurium strains by using a single MLVA protocol. Previously these strains have been identified by pulsed field gel electrophoresis (PFGE) method and it has been shown that each strain produced a distinct PFGE banding profile. One MLVA protocol was tested on 3 serotypes simultaneously and it produced three banding patterns specific to each of the three common Salmonella serotypes. MLVA also constitute a relatively more cost-effective and faster method than PFGE.

Molecular identification of Salmonella Typhimurium from village chickens based on invA and spvC genes.

Aim:This study aimed to identify Salmonella enterica serovars by polymerase chain reaction (PCR) based on virulence genes invasion A (invA) and Salmonella plasmid virulence C (spvC).Materials and Methods:DNA extraction of eight bacteria isolates was done using the PowerSoil® DNA Isolation Kit. The amplification of invA and spvC genes was done using conventional PCR. The positive PCR products were purified using the GeneJET Purification Kit and then sequenced using ABI 3730 XL automated genetic analyzer. The sequences obtained were compared for similarities with other Salmonella serovars deposited on the NCBI GenBank using BLASTN.Results:Four out of eight samples were amplified by primers FS139/RS141 that target invA gene with products of about 284 bp, and three out of four of the same invA positive samples were also amplified by primers FSPV-1/RSPV-2 targeting spvC with a product of about 571 bp. One sample was not amplified by primers FSPV-1/RSPV-2 as it lacked virulence plasmid. Analysis of sequences indicated 100% homology with closely related serovars of S. enterica subspecies enterica serovar Typhimurium.Conclusion:Salmonella Typhimurium that contained invA and spvC genes are pathogenic and virulent strains.

Cholestatic hepatitis in a child with typhoid fever –a case report

Typhoid fever is a common infectious disease in developing countries. It is caused by Salmonella typhi. Salmonella is a genus of the family Enterobacteriaceae. They are rod-shaped, Gram-negative, facultative anaerobic bacteria, most of which are motile by perit¬richous flagella (which bear H antigen [s]). S. Typhi is taxonomically designated as Salmonella enterica subspecies enterica serovar Typhi. In addition to the H antigen (s), 2 polysaccharide surface antigens aid in further characterization of S. enterica, namely the somatic O antigen and capsular Vi (virulence) anti¬gen. Vi antigen is associated with resistance to complement-mediated bacterial lysis and resistance to complement activation by the alternate pathway. Salmonella enterica serovars Paratyphi A and Paraty¬phi B (and uncommonly Paratyphi C) cause a disease (paratyphoid fever) that is clinically indistinguishable from typhoid fever, particularly in parts of Asia. Typhoid fever and paratyphoid fever are collectively termed enteric fever.

Ovarian abscess caused by Salmonella enterica serovar Typhi: a case report

BackgroundTyphoid fever is a human-specific disease caused by a bacterium, Salmonella enterica subspecies enterica serovar Typhi. It is transmitted through ingestion of contaminated food or water. It is mostly diagnosed by blood culture. Salmonella Typhi usually manifests as a febrile illness with bacteremia after initial entry through the gastrointestinal route, but it can occasionally cause significant disease in extraintestinal sites. We report a case of a girl in Fiji with a right ovarian abscess infected by Salmonella Typhi.Case presentationA 14-year-old iTaukei (indigenous Fijian) girl presented to our hospital with abdominal pain of 1 month’s duration. Two days prior to her admission, she developed high-grade fever and nausea and had one episode of vomiting. On presentation, she appeared unwell; she was tachycardic (116 beats per minute) and febrile (38.8 °C). Her abdominal examination revealed generalized tenderness. Other examination findings were normal. The provisional diagnosis of abdominal sepsis led to an emergency laparotomy during which an enlarged right ovary was found to be spontaneously discharging pus. The ovary was incised and drained, and the patient was commenced on intravenous ceftriaxone 1 g twice daily, cloxacillin 1 g four times daily, and metronidazole 500 mg three times daily. She recovered promptly and was discharged to home on the sixth postoperative day. The purulent material from the ovary grew Salmonella Typhi.ConclusionExtraintestinal infections caused by Salmonella Typhi are rare but can cause severe and life-threatening disease. Our patient had a prolonged history of abdominal pain and was found to have a ruptured right ovarian abscess due to Salmonella Typhi. Ovarian abscesses in girls who are not sexually active are not associated with pelvic inflammatory disease and suggest local or hematogenous spread. This case report may increase health workers awareness to include common and endemic infections in the differential diagnosis of unusual clinical presentations to help the initiation of appropriate investigation and management as quickly as possible.

Salmonellosis outbreak with novel Salmonella enterica subspecies enterica serotype (11:z41:e,n,z15) attributable to sesame products in five European countries, 2016 to 2017.

In spring 2016, Greece reported an outbreak caused by a previously undescribed Salmonella enterica subsp. enterica serotype (antigenic formula 11:z41:e,n,z15) via the Epidemic Intelligence Information System for Food- and Waterborne Diseases and Zoonoses (EPIS-FWD), with epidemiological evidence for sesame products as presumptive vehicle. Subsequently, Germany, Czech Republic, Luxembourg and the United Kingdom (UK) reported infections with this novel serotype via EPIS-FWD. Concerned countries in collaboration with the European Centre for Disease Prevention and Control (ECDC) and European Food Safety Authority (EFSA) adopted a common outbreak case definition. An outbreak case was defined as a laboratory-confirmed notification of the novel Salmonella serotype. Between March 2016 and April 2017, 47 outbreak cases were notified (Greece: n = 22; Germany: n = 13; Czech Republic: n = 5; Luxembourg: n = 4; UK: n = 3). Whole genome sequencing revealed the very close genetic relatedness of isolates from all affected countries. Interviews focusing on sesame product consumption, suspicious food item testing and trace-back analysis following Salmonella spp. detection in food products identified a company in Greece where sesame seeds from different countries were processed. Through European collaboration, it was possible to identify and recall sesame spread as one contaminated food item serving as vehicle of infection and trace it back to its origin.

Reptiles in Guadeloupe (French West Indies) are a reservoir of major human Salmonella enterica serovars.

The epidemiology of human Salmonella enterica infections in Guadeloupe (French West Indies) appears to be specific, with a higher prevalence of the subspecies enterica serovars Panama and Arechavaleta (Panama and Arechavaleta) than in other regions. A study was performed in Guadeloupe to identify the reservoir of Salmonella serovars by comparing their distribution in warm- and cold-blooded animals and in humans living in Guadeloupe and mainland France. Furthermore, a case–control study was conducted in 2012–2013 to identify the main epidemiologic risk factors for S. enterica infection among children under 15 years of age. Between June 2011 and December 2014, feces from 426 reptiles (322 anoles, 69 iguanas and 35 geckos) and 50 frogs distributed throughout Guadeloupe and nearby islands were investigated. The frequency of S. enterica carriage was 15.0% (n = 64) in reptiles but varied by species. The only significant risk factor for S. enterica infection was a more frequent presence of frogs in the houses of cases than in those of controls (P = 0.042); however, isolates were not collected. Panama and Arechavaleta were the two serovars most often recovered between 2005 and 2014 from humans living in Guadeloupe (24.5% (n = 174) and 11.5% (n = 82), respectively), which is in contrast to the low prevalence in mainland France (0.4%). Their presence at low frequencies in wild reptiles (4.6% (n = 3) and 3.1% (n = 2), respectively) and pigs (7.5% (n = 5) and 1.5% (n = 1), respectively) suggests a broad host range, and humans may be infected by indirect or direct contact with animals. These serovars are probably poorly adapted to humans and therefore cause more severe infections. The unusual subspecies houtenae serovar 43:z4,z32:- was a major subspecies in wild reptiles (24.6%, n = 16) and humans (9.4%, n = 67) but was not recovered from warm-blooded animals, suggesting that reptiles plays a key role in human infection.

Validation of Solus One Salmonella from Select Food Matrixes and Stainless-Steel and Plastic Environmental Surfaces.

Background: Solus One Salmonella is designed to accurately detect Salmonella species (Salmonella enterica subspecies enterica, salamae, arizonae, diarizonae, houtenae, indica, and Salmonella bongori) from select food matrixes and stainless-steel and plastic environmental surfaces. Solus One Salmonella uses an antibody-based technology test system that is paired with media and our proprietary media supplement, the Solus One Salmonella supplement combined with a manual or automated sample preparation method. Objective: Solus One Salmonella was evaluated for inclusivity and exclusivity, and a matrix comparison study was done for six food matrixes (raw beef trim, pasteurized liquid egg, raw salmon, cheddar cheese, Romaine lettuce, nonfat dry milk) and two environmental surfaces (stainless steel and polystyrene). Methods: Solus One Salmonella was compared with the U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 5: Salmonella (July 2018) and the U.S. Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Manual, 4.09 (January 2017) in the matrix study. Both the manual and automated sample preparation methods were performed for cheddar cheese and stainless-steel environmental surfaces. Results: For the inclusivity and exclusivity evaluation, Solus One Salmonella correctly detected all 108 target organism isolates and correctly excluded all 35 nontarget strains that were analyzed. Conclusions: In the method comparison study, both Solus One Salmonella manual and automated sample preparation methods demonstrated no significant differences based on probability of detection (POD) statistical analysis between presumptive and confirmed results or between candidate and reference method results for the six food matrixes after 20-22 h and two environmental surfaces after 16-20 h of enrichment time. POD analysis of Solus One Salmonella method robustness, product consistency, and stability studies using the automated sample preparation method demonstrated no statistically significant differences.

Spatial Distribution of Salmonella enterica in Poultry Shed Environments Observed by Intensive Longitudinal Environmental Sampling.

Detection of salmonellae within poultry environments is an important component of many food safety programs, but sampling approaches vary greatly and may not enable the detection of salmonellae when bacteria are present at a low prevalence or concentration. Intensive longitudinal sampling within caged sheds enabled us to undertake a longitudinal analysis of the spatial distribution of salmonellae in caged shed environments. Both the number of samples collected and location of sample collection within a poultry shed were important to ensure the best chance of detecting Salmonella spp. Differences in the within-shed spatial distribution of Salmonella enterica subspecies enterica serovar Typhimurium [χ2(27, 1,538) = 54.4; P < 0.001] and Salmonella enterica subspecies enterica serovar Infantis [χ2(27, 1,538) = 79.8; P < 0.0001] were identified. More than one Salmonella enterica serovar was detected in each shed on the same sampling occasion; 5% of all samples contained more than one serovar. Samples collected on the north side of the shed (odds ratio [OR], 1.77; 95% confidence interval [CI], 1.17-2.68), on the sheltered side of the shed (OR, 1.90; 95% CI, 1.26-2.89), and during winter (OR, 48.41; 95% CI, 23.56-104.19) were more likely to be positive for salmonellae. The within-shed differences observed in the both the sample prevalence and spatial location of the serovar detected indicate that there are important shed microenvironmental factors that influence the survival and/or distribution of salmonellae. These factors should be taken into consideration when environmental surveillance is undertaken for salmonellae in flocks housed in cage sheds.IMPORTANCE Routine epidemiological surveillance for salmonellae in poultry relies initially on environmental sampling. Intensive, spatially homogenous sampling, as conducted within this study, confirmed that the sampling methodology conducted within a poultry environment is a nontrivial part of sampling design. The frequency of sampling is especially important when the prevalence of Salmonella spp. is low. These factors must be taken into consideration in the design of studies for the detection of salmonellae in poultry sheds.

The diversity, evolution and ecology of Salmonella in venomous snakes.

BackgroundReptile-associated Salmonella bacteria are a major, but often neglected cause of both gastrointestinal and bloodstream infection in humans globally. The diversity of Salmonella enterica has not yet been determined in venomous snakes, however other ectothermic animals have been reported to carry a broad range of Salmonella bacteria. We investigated the prevalence and diversity of Salmonella in a collection of venomous snakes and non-venomous reptiles.Methodology/Principle findingsWe used a combination of selective enrichment techniques to establish a unique dataset of reptilian isolates to study Salmonella enterica species-level evolution and ecology and used whole-genome sequencing to investigate the relatedness of phylogenetic groups. We observed that 91% of venomous snakes carried Salmonella, and found that a diverse range of serovars (n = 58) were carried by reptiles. The Salmonella serovars belonged to four of the six Salmonella enterica subspecies: diarizonae, enterica, houtanae and salamae. Subspecies enterica isolates were distributed among two distinct phylogenetic clusters, previously described as clade A (52%) and clade B (48%). We identified metabolic differences between S. diarizonae, S. enterica clade A and clade B involving growth on lactose, tartaric acid, dulcitol, myo-inositol and allantoin.SignificanceWe present the first whole genome-based comparative study of the Salmonella bacteria that colonise venomous and non-venomous reptiles and shed new light on Salmonella evolution. Venomous snakes examined in this study carried a broad range of Salmonella, including serovars which have been associated with disease in humans such as S. Enteritidis. The findings raise the possibility that venomous snakes could be a reservoir for Salmonella serovars associated with human salmonellosis.

Dealing with Foodborne Illness: Typhoid Fever, Salmonella Typhi

Typhoid fever is a blood infection caused by consumption of food or water contaminated by the bacterium Salmonella enterica, subspecies enterica, serovar Typhi; commonly referred to as Salmonella typhi or S. typhi. Sometimes you will see the serovar capitalized, i.e., Salmonella Typhi. This is not to be confused with the many other members of the bacterial group Salmonella (often called “non-typhi Salmonella”), which invade the intestines to cause salmonella food poisoning, or salmonellosis. This document is FSHN0514, one of a series of the Food Science and Human Nutrition Department, UF/IFAS Extension. Original publication date August 2005. &#x0D; FSHN0514/FS125: Preventing Foodborne Illness: Typhoid Fever—Salmonella Typhi (ufl.edu)

Evaluation of efflux pump activity of multidrug-resistant Salmonella Typhimurium isolated from poultry wet markets in India.

Introduction: Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) is one of the major cause of foodborne zoonoses in humans. Poultry acts as a reservoir for S. Typhimurium without showing clinical signs and has become a source of infection to humans. Besides, it also became a source of multidrug-resistant (MDR) strains of S. Typhimurium.Methods: In the present study, we have isolated 9 S. Typhimurium from 503 samples from environmental sources of poultry wet markets in the Kadapa District of Andhra Pradesh, India. The role of efflux pump activity in antibiotic resistance was evaluated by ethidium bromide cartwheel test and efflux pump inhibition assay.Results: Eight out of nine isolates were resistant to two or more classes of antibiotics. The efflux pump activity of these isolates by ethidium bromide cartwheel method revealed that 66.6% isolates had shown evidence of pronounced efflux activity. The zone of inhibition (ZOI) of resistant antibiotics for each isolate was estimated in the presence or absence of 25 µg/mL of PAβN. Overall, cephalosporins (cefazolin, cefamandole, and cefaclor), kanamycin, polymyxin-B, piperacillin, and imipenem showed significant increase (≥2 mm) of ZOI, indicating the role of efflux pumps for efflux of these drugs. A maximum of 4 antibiotics among EtBr efflux pump positive isolates and 2 antibiotics among EtBr efflux pump negative isolates showed increased ZOI in the presence of PAβN.Conclusion: The results indicate that efflux pumps of MDR S. Typhimurium may contribute to resistance for at least one antibiotic, even in EtBr cartwheel test negative isolates.

In silico Identification of Serovar-Specific Genes for Salmonella Serotyping.

Salmonella enterica subspecies enterica is a highly diverse subspecies with more than 1500 serovars and the ability to distinguish serovars within this group is vital for surveillance. With the development of whole-genome sequencing technology, serovar prediction by traditional serotyping is being replaced by molecular serotyping. Existing in silico serovar prediction approaches utilize surface antigen encoding genes, core genome MLST and serovar-specific gene markers or DNA fragments for serotyping. However, these serovar-specific gene markers or DNA fragments only distinguished a small number of serovars. In this study, we compared 2258 Salmonella accessory genomes to identify 414 candidate serovar-specific or lineage-specific gene markers for 106 serovars which includes 24 polyphyletic serovars and the paraphyletic serovar Enteritidis. A combination of several lineage-specific gene markers can be used for the clear identification of the polyphyletic serovars and the paraphyletic serovar. We designed and evaluated an in silico serovar prediction approach by screening 1089 genomes representing 106 serovars against a set of 131 serovar-specific gene markers. The presence or absence of one or more serovar-specific gene markers was used to predict the serovar of an isolate from genomic data. We show that serovar-specific gene markers have comparable accuracy to other in silico serotyping methods with 84.8% of isolates assigned to the correct serovar with no false positives (FP) and false negatives (FN) and 10.5% of isolates assigned to a small subset of serovars containing the correct serovar with varied FP. Combined, 95.3% of genomes were correctly assigned to a serovar. This approach would be useful as diagnosis moves to culture-independent and metagenomic methods as well as providing a third alternative to confirm other genome-based analyses. The identification of a set of gene markers may also be useful in the development of more cost-effective molecular assays designed to detect specific gene markers of the all major serovars in a region. These assays would be useful in serotyping isolates where cultures are no longer obtained and traditional serotyping is therefore impossible.

A proposed core genome scheme for analyses of the Salmonella genus

The salmonellae are found in a wide range of animal hosts and many food products for human consumption. Most cases of human disease are caused by S. enterica subspecies I; however as opportunistic pathogens the other subspecies (II-VI) and S. bongori are capable of causing disease. Loci that were not consistently present in all of the species and subspecies were removed from a previously proposed core genome scheme (EBcgMLSTv2.0), the removal of these 252 loci resulted in a core genus scheme (SalmcgMLSTv1.0). SalmcgMLSTv1.0 clustered isolates from the same subspecies more rapidly and more accurately grouped isolates from different subspecies when compared with EBcgMLSTv2.0. All loci within the EBcgMLSTv2.0 scheme were present in over 98% of S. enterica subspecies I isolates and should, therefore, continue to be used for subspecies I analyses, while the SalmcgMLSTv1.0 scheme is more appropriate for cross genus investigations.

Progress in Typhoid Fever Epidemiology.

Salmonella enterica subspecies enterica serovar Typhi (Salmonella Typhi) is the cause of typhoid fever and a human host–restricted organism. Our understanding of the global burden of typhoid fever has improved in recent decades, with both an increase in the number and geographic representation of high-quality typhoid fever incidence studies, and greater sophistication of modeling approaches. The 2017 World Health Organization Strategic Advisory Group of Experts on Immunization recommendation for the introduction of typhoid conjugate vaccines for infants and children aged >6 months in typhoid-endemic countries is likely to require further improvements in our understanding of typhoid burden at the global and national levels. Furthermore, the recognition of the critical and synergistic role of water and sanitation improvements in concert with vaccine introduction emphasize the importance of improving our understanding of the sources, patterns, and modes of transmission of Salmonella Typhi in diverse settings.

Salmonella Infantis in Broiler Flocks in Slovenia: The Prevalence of Multidrug Resistant Strains with High Genetic Homogeneity and Low Biofilm-Forming Ability.

For almost a decade, the number of Salmonella enterica subspecies enterica serovar Infantis-positive broiler flocks has been steadily increasing in Slovenia, doubling the number of positive holdings in only a few years. Since multidrug resistant S. Infantis isolates are highly prevalent in the broiler meat industry and may represent a public health concern through the food chain, we aimed to investigate the antimicrobial susceptibility, genetic diversity, and biofilm-forming ability of S. Infantis from Slovenian broiler flocks. A total of 87 S. Infantis strains isolated from broiler faeces in the period between 2007 and 2013 were studied. The samples originated from 41 farms which were subcontractors of three major food business operators and from two autonomously operating holdings (farms). Isolates were phenotypically tested for their susceptibility to 14 antimicrobials from nine classes by determining the minimum inhibitory concentration with the microdilution method. Only 8% of the isolates were susceptible to all of the antimicrobial agents tested, while 88.5% of the isolates were multidrug resistant, with the most common resistance pattern CipNxSSuT (65.5%) followed by CipNxSuT (17.2%). Pulsed-field gel electrophoresis (PFGE) divided the strains into five clusters (A-E) comprising 16 distinct XbaI PFGE profiles. Sixty-five out of 87 isolates were grouped in clusters A and B, with the predominant PFGE profiles A1 and B1 encompassing 33 and 28 isolates, respectively. A vast majority of the isolates (75/87) showed >90% PFGE profile similarity. The biofilm-forming capacity of the tested isolates, determined with crystal violet assay in polystyrene microwell plates, was generally weak. The average biofilm formation for persistent strains was higher than for presumably nonpersistent strains; however, the difference was not significant. It seems that S. Infantis persistence on broiler farms is more related to its widespread occurrence in the broiler production chain and ineffective disinfection protocols than to its ability to form biofilm.