Anthranilate Acts as a Signal to Modulate Biofilm Formation, Virulence, and Antibiotic Tolerance of Pseudomonas aeruginosa and Surrounding Bacteria

Pseudomonas aeruginosa is a notorious pathogen with high antibiotic resistance, strong virulence, and ability to cause biofilm-mediated chronic infection. We found that these characteristics change profoundly before and after the time when anthranilate is produced as an “anthranilate peak”.

Three Staged Revision Arthroplasty Using Structural Allograft in Chronic Periprosthetic Joint Infection Accompanied by Fracture: A Case Report

Revision arthroplasty for chronic periprosthetic joint infection is complex and determined by many variables. Generally, two-staged revision arthroplasty is the standard treatment for the management of chronic periprosthetic joint infection. However, it is difficult to resolve chronic infection accompanied by large bone deficiency due to pathologic fracture. I report a case of successful three-staged revision arthroplasty using frozen structural allograft in chronic periprosthetic knee joint infection accompanied by extensive bone defect due to fracture.

Dual transcriptomics to determine interferon-gamma independent host response to intestinal Cryptosporidium parvum infection

Animals with a chronic infection of the parasite Toxoplasma gondii are protected against lethal secondary infection with other pathogens. Our group previously determined that soluble T. gondii antigens (STAg) can mimic this protection and be used as a treatment against several lethal pathogens. Because treatments are limited for the parasite Cryptosporidium parvum , we tested STAg as a C. parvum therapeutic. We determined that STAg treatment reduced C. parvum Iowa II oocyst shedding in IFNγ-KO mice. Murine intestinal sections were then sequenced to define the IFNγ independent transcriptomic response to C. parvum infection. Gene Ontology and transcript abundance comparisons showed host immune response and metabolism changes. Transcripts for type I interferon responsive genes were more abundant in C. parvum infected mice treated with STAg. Comparisons between PBS or STAg treatments showed no significant differences in C. parvum gene expression. C. parvum transcript abundance was highest in the ileum and mucin-like glycoproteins and the GDP-fucose transporter were among the most abundant. These results will assist the field in determining both host- and parasite-directed future therapeutic targets.

Tracking Animal Reservoirs of Pathogenic Leptospira: The Right Test for the Right Claim

Leptospirosis is the most prevalent bacterial zoonosis worldwide and, in this context, has been extensively investigated through the One Health framework. Diagnosis of human leptospirosis includes molecular and serological tools, with the serological Microscopic Agglutination Test (MAT) still being considered as the gold standard. Mammals acting as reservoirs of the pathogen include species or populations that are able to maintain chronic infection and shed the bacteria via their urine into the environment. Animals infected by Leptospira are often identified using the same diagnosis tool as in humans, i.e., serological MAT. However, this tool may lead to misinterpretations as it can signal previous infection but does not provide accurate information regarding the capacity of animals to maintain chronic infection and, hence, participate in the transmission cycle. We employ in this paper previously published data and present original results on introduced and endemic small mammals from Indian Ocean islands to show that MAT should not be used for the identification of Leptospira reservoirs. By contrast, serological data are informative on the level of exposure of animals living in a specific environment. We present a sequential methodology to investigate human leptospirosis in the One Health framework that associates molecular detection in humans and animals, together with MAT of human samples using Leptospira isolates obtained from reservoir animals occurring in the same environment.

Predictive significance of the life history of children with gastroesophageal reflux for predicting the development of arrhythmias and conduction disorders

The aim: to improve the early diagnosis of cardiac arrhythmias and conduction disorders in children with gastroesophageal reflux, by studying the prognostic significance of the life history in this group of patients. Materials and methods. 56 children aged 8 to 18 years, mean age 14,93±2,62 years were examined. All examined children were divided into two alternative groups: Group I (main) was represented by 28 children with gastroesophageal reflux in combination with cardiac arrhythmias and conduction disorders, and Group II (control) - 28 children with only gastroesophageal reflux without cardiac arrhythmias and conduction disorders. Patients underwent clinical, anamnestic (with a detailed study of life history) and instrumental studies (electrocardiography, Holter daily ECG monitoring, esophagogastroduodenoscopy). Results. When analyzing the prognostic significance of the patient's life history, it was found that its very high level was observed for the number of foci of chronic infection (I=6.0) and the frequent incidence of a child up to year old of life (I=3.05). High prognostic value was registered relative to the number of diseases suffered by the child per year on average (I=2.35), and moderate predictor properties are characteristic of chickenpox (I=0.89) and the number of chronic diseases at present (I=0.71). The duration of breastfeeding showed low (I=0.30) prognostic significance. Suffered previously bacterial infections did not have predictor properties (I=0.12). In general, the prognostic significance of the patient's life history was high (I̅=2.20). Conclusions. It was found that in general the prognostic significance of the patient's life history was high (I̅=2.20) It is determined that in favour of the development of cardiac arrhythmias and conduction disorders evidence: the number of foci of chronic infection ≥1-2; lack of frequent morbidity in a child up to a year of life; the number of diseases suffered per year ≤5; the presence in past medical history of chickenpox; the number of chronic diseases in a child at present ≤2 and short-term (≤9 months) breastfeeding. It has been established what denies probability of development of the researched pathology: absence of the centers of a chronic infection; the presence frequent incidence of a child up to year old of life; the number of diseases suffered per year≥6, and chronic diseases at present ≥3; longer (≥9 months) breastfeeding and no history of chickenpox

Intraspecific antagonism through viral toxin encoded by chronic Sulfolobus spindle-shaped virus

Virus–host interactions evolve along a symbiosis continuum from antagonism to mutualism. Long-term associations between virus and host, such as those in chronic infection, will select for traits that drive the interaction towards mutualism, especially when susceptible hosts are rare in the population. Virus–host mutualism has been demonstrated in thermophilic archaeal populations where Sulfolobus spindle-shaped viruses (SSVs) provide a competitive advantage to their host Sulfolobus islandicus by producing a toxin that kills uninfected strains. Here, we determine the genetic basis of this killing phenotype by identifying highly transcribed genes in cells that are chronically infected with a diversity of SSVs. We demonstrate that these genes alone confer growth inhibition by being expressed in uninfected cells via a Sulfolobus expression plasmid. Challenge of chronically infected strains with vector-expressed toxins revealed a nested network of cross-toxicity among divergent SSVs, with both broad and specific toxin efficacies. This suggests that competition between viruses and/or their hosts could maintain toxin diversity. We propose that competitive interactions among chronic viruses to promote their host fitness form the basis of virus–host mutualism. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

Genome evolution drives transcriptomic and phenotypic adaptation in Pseudomonas aeruginosa during 20 years of infection

The opportunistic pathogen Pseudomonas aeruginosa chronically infects the lungs of patients with cystic fibrosis (CF). During infection the bacteria evolve and adapt to the lung environment. Here we use genomic, transcriptomic and phenotypic approaches to compare multiple isolates of P. aeruginosa collected more than 20 years apart during a chronic infection in a CF patient. Complete genome sequencing of the isolates, using short- and long-read technologies, showed that a genetic bottleneck occurred during infection and was followed by diversification of the bacteria. A 125 kb deletion, an 0.9 Mb inversion and hundreds of smaller mutations occurred during evolution of the bacteria in the lung, with an average rate of 17 mutations per year. Many of the mutated genes are associated with infection or antibiotic resistance. RNA sequencing was used to compare the transcriptomes of an earlier and a later isolate. Substantial reprogramming of the transcriptional network had occurred, affecting multiple genes that contribute to continuing infection. Changes included greatly reduced expression of flagellar machinery and increased expression of genes for nutrient acquisition and biofilm formation, as well as altered expression of a large number of genes of unknown function. Phenotypic studies showed that most later isolates had increased cell adherence and antibiotic resistance, reduced motility, and reduced production of pyoverdine (an iron-scavenging siderophore), consistent with genomic and transcriptomic data. The approach of integrating genomic, transcriptomic and phenotypic analyses reveals, and helps to explain, the plethora of changes that P. aeruginosa undergoes to enable it to adapt to the environment of the CF lung during a chronic infection.