Over the last 10 years or so, infections caused by bacteria belonging to a particular branch of the genus Francisella have become increasingly recognised in farmed fish and molluscs worldwide. While the increasing incidence of diagnoses may in part be due to the development and widespread availability of molecular detection techniques, the domestication of new organisms has undoubtedly instigated emergence of clinical disease in some species. Francisellosis in fish develops in a similar fashion independent of host species and is commonly characterised by the presence of multi-organ granuloma and high morbidity, with varying associated mortality levels. A number of fish species are affected including Atlantic cod, Gadus morhua; tilapia, Oreochromis sp.; Atlantic salmon, Salmo salar; hybrid striped bass, Morone chrysops × M. saxatilis and three-lined grunt, Parapristipoma trilinineatum. The disease is highly infectious and often prevalent in affected stocks. Most, if not all strains isolated from teleost fish belong to either F. noatunensis subsp. orientalis in warm water fish species or Francisella noatunensis subsp. noatunensis in coldwater fish species. The disease is quite readily diagnosed following histological examination and identification of the aetiological bacterium by culture on cysteine rich media or PCR. The available evidence may indicate a degree of host specificity for the various Francisella strains, although this area requires further study. No effective vaccine is currently available. Investigation of the virulence mechanisms and host response shows similarity to those known from Francisella tularensis infection in mammals. However, no evidence exists for zoonotic potential amongst the fish pathogenic Francisella.

BackgroundPrior to this study, relatively few strains of Francisella had been genome-sequenced. Previously published Francisella genome sequences were largely restricted to the zoonotic agent F. tularensis. Only limited data were available for other members of the Francisella genus, including F. philomiragia, an opportunistic pathogen of humans, F. noatunensis, a serious pathogen of farmed fish, and other less well described endosymbiotic species.ResultsWe determined the phylogenetic relationships of all known Francisella species, including some for which the phylogenetic positions were previously uncertain. The genus Francisella could be divided into two main genetic clades: one included F. tularensis, F. novicida, F. hispaniensis and Wolbachia persica, and another included F. philomiragia and F. noatunensis.Some Francisella species were found to have significant recombination frequencies. However, the fish pathogen F. noatunensis subsp. noatunensis was an exception due to it exhibiting a highly clonal population structure similar to the human pathogen F. tularensis.ConclusionsThe genus Francisella can be divided into two main genetic clades occupying both terrestrial and marine habitats. However, our analyses suggest that the ancestral Francisella species originated in a marine habitat. The observed genome to genome variation in gene content and IS elements of different species supports the view that similar evolutionary paths of host adaptation developed independently in F. tularensis (infecting mammals) and F. noatunensis subsp. noatunensis (infecting fish).

Sepsis is a life-threatening systemic illness attributed to a dysregulated host response to infection. Sepsis is a global burden killing ~11 million persons annually. In December 2019, a novel pneumonia condition termed coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged and has resulted in more than 1,535,982 deaths globally as of 8th December 2020. These two conditions share many pathophysiological and clinical features. Notably, both sepsis and COVID-19 patients experience consumptive thrombocytopenia, haemolytic anaemia, vascular microthrombosis, multi-organ dysfunction syndrome, coagulopathy, septic shock, respiratory failure, fever, leukopenia, hypotension, leukocytosis, high cytokine production and high predisposition to opportunistic infections. Considering the parallels in the immunopathogenesis and pathophysiological manifestations of sepsis and COVID-19, it is highly likely that sepsis care, which has a well-established history in most health systems, could inform on COVID-19 management. In view of this, the present perspective compares the immunopathogenesis and pathophysiology of COVID-19 and non-SARS-CoV-2 induced sepsis, and lessons from sepsis that can be applicable to COVID-19 management.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) poses a public health threat owing to its extensive resistance to antibiotics, association with persistent outbreaks, and markedly increased healthcare costs. Moreover, HIV-infected individuals are at a greater risk for colonization with MRSA, and may act as reservoirs for subsequent transmission to other individuals. In Ghana, little is known about MRSA in relation to at-risk populations, such as HIV-infected children. The aim of this study was to investigate nasal carriage of S. aureus and MRSA among HIV-infected children in Accra, including the prevalence, risk factors and antibiotic resistance. Methodology: The study was cross-sectional, and involved 107 children with HIV infection and an equal number of sex- and age group- matched apparently healthy controls recruited from the Princess Marie Louis Children’s Hospital in Accra. Nasal swab specimens were collected from the study participants and cultured for bacteria. S. aureus isolates were confirmed by the coagulase test while MRSA was confirmed by PCR of the mecA gene. Antimicrobial susceptibility testing of S. aureus isolates was done by the Kirby Bauer method. A structured questionnaire was used to collect data on demographic, household and clinical features of the study participants. A logistic regression analysis was performed to identify determinants of S. aureus and MRSA carriage among participants of both study groups. Results: The carriage prevalence of S. aureus and MRSA were 44.9% (48) and 5.6% (6), respectively, among the HIV-infected individuals, and the corresponding values within the control group were 23.4% (25) and 0.9% (1). There was a significant association between HIV infection and S. aureus colonization (p < 0.001), but not MRSA colonization (p = 0.055). The main predictor of S. aureus colonization in both study groups was absence of colonization with coagulase negative staphylococcus (p < 0.001). Furthermore, the main predictor of MRSA colonization was regular hand washing with soap (p = 0.043); this was observed among HIV-infected individuals but not the control group. The proportion of S. aureus isolates that were multidrug resistant was 62.3% (33/53) in the HIV-infected group and 80% (20/25) in the control group (p = 0.192). Conclusions: HIV infection is a risk factor for nasal colonization of S. aureus among children in Accra but may not be for MRSA. Both the HIV-infected and uninfected children are reservoirs of multidrug resistant S. aureus. Demographic, household and clinical features appear to have little or no relationship with S. aureus and MRSA colonization in the study children.

cInfections with Bartonella spp. have been recognized as emerging zoonotic diseases in humans. Large knowledge gaps exist, however, relating to reservoirs, vectors, and transmission of these bacteria. We describe identification by culture, PCR, and housekeeping gene sequencing of Bartonella spp. in fed, wingless deer keds (Lipoptena cervi), deer ked pupae, and blood samples collected from moose, Alces alces, sampled within the deer ked distribution range in Norway. Direct sequencing from moose blood sampled in a deer ked-free area also indicated Bartonella infection but at a much lower prevalence. The sequencing data suggested the presence of mixed infections involving two species of Bartonella within the deer ked range, while moose outside the range appeared to be infected with a single species. Bartonella were not detected or cultured from unfed winged deer keds. The results may indicate that long-term bacteremia in the moose represents a reservoir of infection and that L. cervi acts as a vector for the spread of infection of Bartonella spp. Further research is needed to evaluate the role of L. cervi in the transmission of Bartonella to animals and humans and the possible pathogenicity of these bacteria for humans and animals.