Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections.

Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015.

Clinical indicators for bacterial co-infection in Ghanaian children with P. falciparum infection.

Differentiation of infectious causes in severely ill children is essential but challenging in sub- Saharan Africa. The aim of the study was to determine clinical indicators that are able to identify bacterial co-infections in P. falciparum infected children in rural Ghana. In total, 1,915 severely ill children below the age of 15 years were recruited at Agogo Presbyterian Hospital in Ghana between May 2007 and February 2011. In 771 (40%) of the children malaria parasites were detected. This group was analyzed for indicators of bacterial co-infections using bivariate and multivariate regression analyses with 24 socio-economic variables, 16 terms describing medical history and anthropometrical information and 68 variables describing clinical symptoms. The variables were tested for sensitivity, specificity, positive predictive value and negative predictive value. In 46 (6.0%) of the children with malaria infection, bacterial co-infection was detected. The most frequent pathogens were non-typhoid salmonellae (45.7%), followed by Streptococcus spp. (13.0%). Coughing, dehydration, splenomegaly, severe anemia and leukocytosis were positively associated with bacteremia. Domestic hygiene and exclusive breastfeeding is negatively associated with bacteremia. In cases of high parasitemia (>10,000/µl), a significant association with bacteremia was found for splenomegaly (OR 8.8; CI 1.6-48.9), dehydration (OR 18.2; CI 2.0-166.0) and coughing (OR 9.0; CI 0.7-118.6). In children with low parasitemia, associations with bacteremia were found for vomiting (OR 4.7; CI 1.4-15.8), severe anemia (OR 3.3; CI 1.0-11.1) and leukocytosis (OR 6.8 CI 1.9-24.2). Clinical signs of impaired microcirculation were negatively associated with bacteremia. Ceftriaxone achieved best coverage of isolated pathogens. The results demonstrate the limitation of clinical symptoms to determine bacterial co-infections in P. falciparum infected children. Best clinical indicators are dependent on the parasitemia level. Even with a moderate sensitivity of >60%, only low positive predictive values can be obtained due to low prevalence of bacteremia. Rapid testing for distinguishing parasitemia and bacteremia is essential.

Stably integrated luxCDABE for assessment of Salmonella invasion kinetics.

Salmonella Typhimurium is a common cause of gastroenteritis in humans and also localizes to neoplastic tumors in animals. Invasion of specific eukaryotic cells is a key mechanism of Salmonella interactions with host tissues. Early stages of gastrointestinal cell invasion are mediated by a Salmonella type III secretion system, powered by the adenosine triphosphatase invC. The aim of this work was to characterize the invC dependence of invasion kinetics into disparate eukaryotic cells traditionally used as models of gut epithelium or neoplasms. Thus, a nondestructive real-time assay was developed to report eukaryotic cell invasion kinetics using lux+ Salmonella that contain chromosomally integrated luxCDABE genes. Bioluminescence-based invasion assays using lux+ Salmonella exhibited inoculum dose-response correlation, distinguished invasion-competent from invasion-incompetent Salmonella, and discriminated relative Salmonella invasiveness in accordance with environmental conditions that induce invasion gene expression. In standard gentamicin protection assays, bioluminescence from lux+ Salmonella correlated with recovery of colony-forming units of internalized bacteria and could be visualized by bioluminescence microscopy. Furthermore, this assay distinguished invasion-competent from invasion-incompetent bacteria independent of gentamicin treatment in real time. Bioluminescence reported Salmonella invasion of disparate eukaryotic cell lines, including neoplastic melanoma, colon adenocarcinoma, and glioma cell lines used in animal models of malignancy. In each case, Salmonella invasion of eukaryotic cells was invC dependent.

The study of infectious intestinal disease in England: socio-economic impact.

To assess the socio-economic impact of infectious intestinal disease (IID) on the health care sector, cases and their families, cases of IID ascertained from a population cohort component and those presenting to general practices were sent a socio-economic questionnaire 3 weeks after the acute episode. The impact of the illness was measured and the resources used were identified and costed. The duration, severity and costs of illness linked to viruses were less than those linked to bacteria. The average cost per case of IID presenting to the GP was Pound Sterling253 and the costs of those not seeing a GP were Pound Sterling34. The average cost per case was Pound Sterling606 for a case with salmonella, Pound Sterling315 for campylobacter, Pound Sterling164 for rotavirus and Pound Sterling176 for SRSV. The estimated cost of IID in England was Pound Sterling743m expressed in 1994/5 prices. The costs of IID are considerable and the duration of the illness was found to be longer than previous reports have suggested.