Salmonella Derby adaptation to swine and simultaneous attenuation for humans go through decay of Salmonella Pathogenicity Island I.

IMPORTANCE: This study integrated population data with in vitro assessment of virulence phenotypes to unveil that a considerable part of the global population of Salmonella Derby is evolving to enhance its host adaptation to the swine host and that this evolution is simultaneously increasing its attenuation for humans. The study shows that the fixation of deleterious mutations in SPI-1 has a role in this process. This evidence indicates that SPI-1 has a key role for S. Derby virulence in humans but not for its circulation in swine. The results show that genes generally considered essential for Salmonella pathogenesis do not play the same key role for all Salmonella serovars or lineages and/or all hosts. The study helps in understanding the molecular mechanisms underlying the ecology and host adaptation of Salmonella showing that the adaptation process can vary for different types of Salmonella and hosts.

Listeria monocytogenes Transmission from Donated Blood to Platelet Transfusion Recipient, Italy.

We report Listeria monocytogenes infection in a patient in Italy who was transfused with pooled platelet concentrate. Genomic analysis revealed that L. monocytogenes isolates from the donor blood unit, the transfused platelets, and the patient's blood culture were genetically closely related, confirming transfusion transmission. Additional surveillance and secondary bacterial screening could improve transfusion safety.

A Fatal Case of Pseudomonas aeruginosa Community-Acquired Pneumonia in an Immunocompetent Patient: Clinical and Molecular Characterization and Literature Review.

Rare cases of Pseudomonas aeruginosa community-acquired pneumonia (PA-CAP) were reported in non-immunocompromised patients. We describe a case of Pseudomonas aeruginosa (PA) necrotizing cavitary CAP with a fatal outcome in a 53-year-old man previously infected with SARS-CoV-2, who was admitted for dyspnea, fever, cough, hemoptysis, acute respiratory failure and a right upper lobe opacification. Six hours after admission, despite effective antibiotic therapy, he experienced multi-organ failure and died. Autopsy confirmed necrotizing pneumonia with alveolar hemorrhage. Blood and bronchoalveolar lavage cultures were positive for PA serotype O:9 belonging to ST1184. The strain shares the same virulence factor profile with reference genome PA01. With the aim to better investigate the clinical and molecular characteristics of PA-CAP, we considered the literature of the last 13 years concerning this topic. The prevalence of hospitalized PA-CAP is about 4% and has a mortality rate of 33-66%. Smoking, alcohol abuse and contaminated fluid exposure were the recognized risk factors; most cases presented the same symptoms described above and needed intensive care. Co-infection of PA-influenza A is described, which is possibly caused by influenza-inducing respiratory epithelial cell dysfunction: the same pathophysiological mechanism could be assumed with SARS-CoV-2 infection. Considering the high rate of fatal outcomes, additional studies are needed to identify sources of infections and new risk factors, along with genetic and immunological features. Current CAP guidelines should be revised in light of these results.

Different Roles of Wild Boars and Livestock in Salmonella Transmission to Humans in Italy.

Wild boar (Sus scrofa) is the most widely distributed large wildlife mammal worldwide. To investigate the transmission of Salmonella enterica amongst wild boars (Sus scrofa), humans, and livestock, we compared via pulsed-field gel electrophoresis and whole genome sequences the isolates of S. enterica serovar Typhimurium (biphasic and monophasic variants) and Enteritidis collected from wild boars, food-producing animals, and human patients in Emilia-Romagna region (Northern Italy) between 2017 and 2020. Specifically, we analysed 2175 isolates originated from human (1832), swine (117), bovine (128), poultry (76), and wild boar (22). The genomic analyses showed that wild boars shared most of their lineages of biphasic Typhimurium with bovines and most of Enteritidis with poultry, whilst we did not find any lineage shared with swine. Moreover, almost 17% of human biphasic Typhimurium and Enteritidis belonged to genomic clusters including wild boar isolates, but the inclusion of bovine and poultry isolates in the same clusters and the peculiar spatial distribution of the isolates suggested that human cases (and wild boar infections) likely originated from bovines and poultry. Consequently, wild boars appear not to play a significant role in infecting humans with these serovars, but seem to get infected themselves from livestock, probably through the environment.

Klebsiella pneumoniae carrying multiple alleles of antigen 43-encoding gene of Escherichia coli associated with biofilm formation.

A clinical strain of Klebsiella pneumoniae typed as sequence type 307 carrying three different alleles of the flu gene encoding the Escherichia coli virulence factor antigen 43 associated with biofilm formation was detected and characterized. The flu alleles are located in the chromosome inside putative integrative conjugative elements. The strain displays the phenotypes associated with Ag43, i.e. bi-phasic colony morphology and enhanced biofilm production. Furthermore, the strain produces low amount of capsule known to affect Ag43 function. Analysis of 1431 worldwide deposited genomes revealed that 3.7% Klebsiella pneumoniae carry one or two flu alleles.

Machine learning-based typing of Salmonella enterica O-serogroups by the Fourier-Transform Infrared (FTIR) Spectroscopy-based IR Biotyper system.

BACKGROUND: Salmonella enterica is among the major burdens for public health at global level. Typing of salmonellae below the species level is fundamental for different purposes, but traditional methods are expensive, technically demanding, and time-consuming, and therefore limited to reference centers. Fourier transform infrared (FTIR) spectroscopy is an alternative method for bacterial typing, successfully applied for classification at different infra-species levels. AIM: This study aimed to address the challenge of subtyping Salmonella enterica at O-serogroup level by using FTIR spectroscopy. We applied machine learning to develop a novel approach for S. enterica typing, using the FTIR-based IR Biotyper® system (IRBT; Bruker Daltonics GmbH & Co. KG, Germany). We investigated a multicentric collection of isolates, and we compared the novel approach with classical serotyping-based and molecular methods. METHODS: A total of 958 well characterized Salmonella isolates (25 serogroups, 138 serovars), collected in 11 different centers (in Europe and Japan), from clinical, environmental and food samples were included in this study and analyzed by IRBT. Infrared absorption spectra were acquired from water-ethanol bacterial suspensions, from culture isolates grown on seven different agar media. In the first part of the study, the discriminatory potential of the IRBT system was evaluated by comparison with reference typing method/s. In the second part of the study, the artificial intelligence capabilities of the IRBT software were applied to develop a classifier for Salmonella isolates at serogroup level. Different machine learning algorithms were investigated (artificial neural networks and support vector machine). A subset of 88 pre-characterized isolates (corresponding to 25 serogroups and 53 serovars) were included in the training set. The remaining 870 samples were used as validation set. The classifiers were evaluated in terms of accuracy, error rate and failed classification rate. RESULTS: The classifier that provided the highest accuracy in the cross-validation was selected to be tested with four external testing sets. Considering all the testing sites, accuracy ranged from 97.0% to 99.2% for non-selective media, and from 94.7% to 96.4% for selective media. CONCLUSIONS: The IRBT system proved to be a very promising, user-friendly, and cost-effective tool for Salmonella typing at serogroup level. The application of machine learning algorithms proved to enable a novel approach for typing, which relies on automated analysis and result interpretation, and it is therefore free of potential human biases. The system demonstrated a high robustness and adaptability to routine workflows, without the need of highly trained personnel, and proving to be suitable to be applied with isolates grown on different agar media, both selective and unselective. Further tests with currently circulating clinical, food and environmental isolates would be necessary before implementing it as a potentially stand-alone standard method for routine use.

Comparative analysis of two genomes of Chlamydia pecorum isolates from an Alpine chamois and a water buffalo.

BACKGROUND: To date, whole genome sequencing has been performed mainly for isolates of Chlamydia trachomatis, C. pneumoniae, C. psittaci and C. abortus, but only a few isolates of C. pecorum have been entirely sequenced and this makes it difficult to understand its diversity and population structure. In this study the genome of two C. pecorum strains isolated from the lung of an Alpine chamois affected with pneumonia (isolate PV7855) and the brain of a water buffalo affected with meningoencephalomyelitis (isolate PV6959), were completely sequenced with MiSeq system (Illumina) and analyzed in their most polymorphic regions. RESULTS: The genome length and GC content of the two isolates were found to be consistent with other C. pecorum isolates and the gene content of polymorphic membrane proteins and plasticity zone was found to be very similar. Some differences were observed in the phospholipase genes for both isolates and in the number of genes in the plasticity zone, such as the presence of some hypothetical proteins in PV6959, not present in any other genomes analyzed in this study. Interestingly, PV6959 possesses an extra pmp and has an incomplete tryptophan biosynthesis operon. Plasmids were detected in both isolates. CONCLUSIONS: Genome sequencing of the two C. pecorum strains did not reveal differences in length and GC content despite the origin from different animal species with different clinical disease. In the plasticity zone, the differences in the genes pattern might be related to the onset of specific symptoms or infection of specific hosts. The absence of a tryptophan biosynthesis pathway in PV6959 may suggest a strict relationship between C. pecorum and its host.

Automated Analysis of Intracellular Phenotypes of Salmonella using ImageJ.

Salmonella is an enteric pathogen able to invade the intestinal epithelium and replicate in enterocytes, both inside Salmonella-specific vacuoles and free in the cytosol (cytosolic hyper-replication). These different phenotypes of intracellular replication drive to different pathways of pathogenesis, i.e., cytosolic hyper-replication induces inflammatory cell death and extrusion into the gut lumen, while vacuolar replication leads to trans-epithelium penetration and systemic spread. Significant effort was made to create microscopy tools to study the behavior of Salmonella inside invaded cells, such as the pCHAR-Duo fluorescence reporter plasmid that allows discrimination between vacuolar and cytosolic bacteria by differential expression of mCherry and GFP. However, intracellular phenotypes are often manually scored, a time-consuming procedure that limits analysis to a small number of samples and cells. To overcome these limitations, two complementary and automated image analyses were developed using ImageJ, a freely available image analysis software. In the high-throughput protocol, epithelial cells were infected with Salmonella carrying pCHAR-Duo using 96-well plates. Imaging was performed using an automated fluorescence microscope. Then, two image analysis methods were applied to measure the intracellular behavior of Salmonella at different detail levels. The first method measures the overall intracellular bacterial load and the extent of cytosolic hyper-replication. It is fast and allows the scoring of a high number of cells and samples, making it suitable for high-throughput assays such as screening experiments. The second method performs single-cell analysis to determine the percentage of infected cells, the mean vacuolar load of Salmonella, and the cytosolic hyper-replication rate giving greater details about Salmonella behavior inside epithelial cells. The protocols can be performed by specifically designed ImageJ scripts to automatically run batch analyses of the major steps of Salmonella-enterocyte interaction.

Competition for dominance within replicating quasispecies during prolonged SARS-CoV-2 infection in an immunocompromised host.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) emerge for their capability to better adapt to the human host aimed and enhance human-to-human transmission. Mutations in spike largely contributed to adaptation. Viral persistence is a prerequisite for intra-host virus evolution, and this likely occurred in immunocompromised patients who allow intra-host long-term viral replication. The underlying mechanism leading to the emergence of variants during viral persistence in the immunocompromised host is still unknown. Here, we show the existence of an ensemble of minor mutants in the early biological samples obtained from an immunocompromised patient and their dynamic interplay with the master mutant during a persistent and productive long-term infection. In particular, after 222 days of active viral replication, the original master mutant, named MB610, was replaced by a minor quasispecies (MB61222) expressing two critical mutations in spike, namely Q493K and N501T. Isolation of the two viruses allowed us to show that MB61222 entry into target cells occurred mainly by the fusion at the plasma membrane (PM), whereas endocytosis characterized the entry mechanism used by MB610. Interestingly, coinfection of two human cell lines of different origin with the SARS-CoV-2 isolates highlighted the early and dramatic predominance of MB61222 over MB610 replication. This finding may be explained by a faster replicative activity of MB61222 as compared to MB610 as well as by the capability of MB61222 to induce peculiar viral RNA-sensing mechanisms leading to an increased production of interferons (IFNs) and, in particular, of IFN-induced transmembrane protein 1 (IFITM1) and IFITM2. Indeed, it has been recently shown that IFITM2 is able to restrict SARS-CoV-2 entry occurring by endocytosis. In this regard, MB61222 may escape the antiviral activity of IFITMs by using the PM fusion pathway for entry into the target cell, whereas MB610 cannot escape this host antiviral response during MB61222 coinfection, since it has endocytosis as the main pathway of entry. Altogether, our data support the evidence of quasispecies fighting for host dominance by taking benefit from the cell machinery to restrict the productive infection of competitors in the viral ensemble. This finding may explain, at least in part, the extraordinary rapid worldwide turnover of VOCs that use the PM fusion pathway to enter into target cells over the original pandemic strain.

Versatile Supramolecular Complex for Targeted Antimicrobial Photodynamic Inactivation.

We report the development of a supramolecular structure endowed with photosensitizing properties and targeting capability for antimicrobial photodynamic inactivation. Our synthetic strategy uses the tetrameric bacterial protein streptavidin, labeled with the photosensitizer eosin, as the main building block. Biotinylated immunoglobulin G (IgG) from human serum, known to associate with Staphylococcus aureus protein A, was bound to the complex streptavidin-eosin. Fluorescence correlation spectroscopy and fluorescence microscopy demonstrate binding of the complex to S. aureus. Efficient photoinactivation is observed for S. aureus suspensions treated with IgG-streptavidin-eosin at concentrations higher than 0.5 µM and exposed to green light. The proposed strategy offers a flexible platform for targeting a variety of molecules and microbial species.

Identification of a New Serovar of Salmonella enterica in Mediterranean Buffalo Calves (Bubalus bubalis).

This case report describes for the first-time cases of severe gastroenteritis in water buffalo calves due to a new serovar of Salmonella enterica. The study was carried out on fecal matrix collected from live water buffalo calves that showed profuse diarrhea, severe dehydration and fever, exhibiting a systemic course. Culture and molecular investigations identified the pathogens isolated from intestinal contents as two Salmonella serovars, Salmonella enterica enterica O:35 and a new serovar of Salmonella enterica. The isolates showed multi-drug resistance. Timely diagnosis associated with a targeted antimicrobial treatment were found to be sufficient for the survival and recovery of the infected animals. Herd vaccines prepared from isolated pathogens were used to prevent further deaths of the calves.

Reduction trend of mcr-1 circulation in Emilia-Romagna Region, Italy.

This study aims to describe trends of mcr-positive Enterobacterales in humans based on laboratory surveillance with a defined catchment population. The data source is the Micro-RER surveillance system, established in Emilia-Romagna region (Italy), to monitor the trend of mcr resistance. Enterobacterales isolates from human clinical samples with minimum inhibitory concentration (MIC) ≥ 2 mg/L for colistin were sent to the study reference laboratory for the detection of mcr genes. Isolates prospectively collected in the period 2018-2020 were considered for the assessment of population rates and trends; further analyses were carried out for the evaluation of clonality and horizontal mcr gene transfer. Previous isolates from local laboratory collection were also described. In the period 2018-2020, 1164 isolates were sent to the reference laboratory, and 51 (4.4%) were confirmed as mcr-positive: 50 mcr-1 (42 Escherichia coli, 6 Klebsiella pneumoniae, 2 Salmonella enterica) and 1 mcr-4 (Enterobacter cloacae). The number of mcr-positive isolates dropped from 24 in the first half of 2018 to 3 in the whole of 2020 (trend p value < 0.001). Genomic analyses showed the predominant role of the horizontal transfer of mcr genes through plasmids or dissemination of transposable elements compared to clonal dissemination of mcr-positive microorganisms. The study results demonstrate a substantial decrease in the circulation of mcr-1 plasmid genes in Emilia-Romagna Region.

Classification of Salmonella enterica of the (Para-)Typhoid Fever Group by Fourier-Transform Infrared (FTIR) Spectroscopy.

Typhoidal and para-typhoidal Salmonella are major causes of bacteraemia in resource-limited countries. Diagnostic alternatives to laborious and resource-demanding serotyping are essential. Fourier transform infrared spectroscopy (FTIRS) is a rapidly developing and simple bacterial typing technology. In this study, we assessed the discriminatory power of the FTIRS-based IR Biotyper (Bruker Daltonik GmbH, Bremen, Germany), for the rapid and reliable identification of biochemically confirmed typhoid and paratyphoid fever-associated Salmonella isolates. In total, 359 isolates, comprising 30 S. Typhi, 23 S. Paratyphi A, 23 S. Paratyphi B, and 7 S. Paratyphi C, respectively and other phylogenetically closely related Salmonella serovars belonging to the serogroups O:2, O:4, O:7 and O:9 were tested. The strains were derived from clinical, environmental and food samples collected at different European sites. Applying artificial neural networks, specific automated classifiers were built to discriminate typhoidal serovars from non-typhoidal serovars within each of the four serogroups. The accuracy of the classifiers was 99.9%, 87.0%, 99.5% and 99.0% for Salmonella Typhi, Salmonella Paratyphi A, B and Salmonella Paratyphi C, respectively. The IR Biotyper is a promising tool for fast and reliable detection of typhoidal Salmonella. Hence, IR biotyping may serve as a suitable alternative to conventional approaches for surveillance and diagnostic purposes.

Economic evaluation of whole genome sequencing for pathogen identification and surveillance - results of case studies in Europe and the Americas 2016 to 2019.

BackgroundWhole genome sequencing (WGS) is increasingly used for pathogen identification and surveillance.AimWe evaluated costs and benefits of routine WGS through case studies at eight reference laboratories in Europe and the Americas which conduct pathogen surveillance for avian influenza (two laboratories), human influenza (one laboratory) and food-borne pathogens (five laboratories).MethodsThe evaluation focused on the institutional perspective, i.e. the 'investment case' for implementing WGS compared with conventional methods, based on costs and benefits during a defined reference period, mostly covering at least part of 2017. A break-even analysis estimated the number of cases of illness (for the example of Salmonella surveillance) that would need to be avoided through WGS in order to 'break even' on costs.ResultsOn a per-sample basis, WGS was between 1.2 and 4.3 times more expensive than routine conventional methods. However, WGS brought major benefits for pathogen identification and surveillance, substantially changing laboratory workflows, analytical processes and outbreaks detection and control. Between 0.2% and 1.1% (on average 0.7%) of reported salmonellosis cases would need to be prevented to break even with respect to the additional costs of WGS.ConclusionsEven at cost levels documented here, WGS provides a level of additional information that more than balances the additional costs if used effectively. The substantial cost differences for WGS between reference laboratories were due to economies of scale, degree of automation, sequencing technology used and institutional discounts for equipment and consumables, as well as the extent to which sequencers are used at full capacity.

Genomic Characterization of VIM and MCR Co-Producers: The First Two Clinical Cases, in Italy.

BACKGROUND: the co-production of carbapenemases and mcr-genes represents a worrisome event in the treatment of Enterobacteriaceae infections. The aim of the study was to characterize the genomic features of two clinical Enterobacter cloacae complex (ECC) isolates, co-producing VIM and MCR enzymes, in Italy. METHODS: species identification and antibiotic susceptibility profiling were performed using MALDI-TOF and broth microdilution methods, respectively. Transferability of the bla VIM- and mcr- type genes was verified through conjugation experiment. Extracted DNA was sequenced using long reads sequencing technology on the Sequel I platform (PacBio). RESULTS: the first isolate showed clinical resistance against ertapenem yet was colistin susceptible (EUCAST 2020 breakpoints). The mcr-9.2 gene was harbored on a conjugative IncHI2 plasmid, while the bla VIM-1 determinant was harbored on a conjugative IncN plasmid. The second isolate, resistant to both carbapenems and colistin, harbored: mcr-9 gene and its two component regulatory genes for increased expression on the chromosome, mcr-4.3 on non-conjugative (yet co-transferable) ColE plasmid, and bla VIM-1 on a non-conjugative IncA plasmid. CONCLUSIONS: to our knowledge, this is the first report of co-production of VIM and MCR in ECC isolates in Italy.

Mutation of hilD in a Salmonella Derby lineage linked to swine adaptation and reduced risk to human health.

Salmonella enterica variants exhibit diverse host adaptation, outcome of infection, and associated risk to food safety. Analysis of the distribution of Salmonella enterica serovar Derby (S. Derby) subtypes in human and swine identified isolates with a distinct PFGE profile that were significantly under-represented in human infections, consistent with further host adaptation to swine. Here we show that isolates with this PFGE profile form a distinct phylogenetic sub-clade within S. Derby and exhibit a profound reduction in invasion of human epithelial cells, and a relatively small reduction in swine epithelial cells. A single missense mutation in hilD, that encodes the master-regulator of the Salmonella Pathogenicity Island 1 (SPI-1), was present in the adapted lineage. The missense mutation resulted in a loss of function of HilD that accounted for reduced invasion in human epithelial cells. The relatively small impact of the mutation on interaction with swine cells was consistent with an alternative mechanism of invasion in this pathogen-host combination.

Paratuberculosis in Captive Scimitar-Horned Oryxes (Oryx dammah).

Paratuberculosis, a chronic disease caused by Mycobacterium avium subsp. paratuberculosis (MAP), in ten scimitar-horned oryxes (SHOs) hosted in an Italian zoological park and originating from a Slovakian flock, was documented by pathology, molecular, cultural, and serological testing. The infection origin in this threatened species was also investigated by genomic analyses. Following the death of six of the 10 SHOs, serial investigations of dead and alive animals were performed. Necropsy, carried out on five out of six animals, identified intestinal thickening and mesenteric lymphadenomegaly in one of the animals. Histopathology (5/6) revealed lepromatous (2/5) and tuberculoid (2/5) intestinal forms or lack of lesions (1/5). Ziehl-Neelsen and immunohistochemistry stains identified two multibacillary, two paucibacillary forms, and one negative case. MAP was identified by quantitative PCR (qPCR) in tissue samples in five out of five SHOs and was microbiologically isolated from two of the three animals whose fresh tissue samples were available. Fecal samples were collected in four of the six dead animals: all four resulted positive to qPCR and in MAP was isolated in three. ELISA identified MAP-specific antibodies in three of the five dead animals whose serum was available. qPCR identified MAP in the freshly deposited feces of two out of the four alive animals. From the feces of these two animals, MAP was microbiologically isolated in one case. All isolates were classified as MAP type C and profiled as INMV2 and MVS27 by molecular analysis. Genomic analysis of a field isolate revealed clusterization with a European clade but was more similar to Italian than East European isolates. Our findings underline that paratuberculosis should always be considered in zoological parks in which endangered species are hosted. Infection can be subclinical, and multiple combined testing techniques may be necessary.

Population Structure of Listeria monocytogenes in Emilia-Romagna (Italy) and Implications on Whole Genome Sequencing Surveillance of Listeriosis.

The population structure of human isolates of Listeria monocytogenes in Emilia-Romagna, Italy, from 2012 to 2018 was investigated with the aim of evaluating the presence of genomic clusters indicative of possible outbreaks, the proportion of cluster-associated vs. sporadic isolates and different methods and metrics of genomic analysis for use in routine surveillance. In the 2012-2018 period the notification rate of confirmed invasive cases in Emilia-Romagna was 0.91 per 100,000 population per year, more than twice the average rate of EU countries. Out of the total 283 cases, 268 (about 95%) isolates were typed through whole genome sequencing (WGS) for cluster detection with methods based on core-genome multi-locus sequence typing and single nucleotide polymorphisms. Between 66 and 72% of listeriosis cases belonged to genomic clusters which included up to 27 cases and lasted up to 5 years. This proportion of cluster-associated cases is higher than previously estimated in other European studies. Rarefaction analysis, performed by reducing both the number of consecutive years of surveillance considered and the proportion of isolates included in the analysis, suggested that the observed high proportion of cluster-associated cases can be ascribed to the long surveillance duration (7 years) and the high notification and typing rates of this study. Our findings show that a long temporal perspective and high surveillance intensity, intended as both exhaustiveness of the system to report cases and high WGS-typing rate, are critical for sensitive detection of possible outbreaks within a WGS-based surveillance of listeriosis. Furthermore, the power and complexity of WGS interpretation emerged from the integration of genomic and epidemiological information in the investigation of few past outbreaks within the study, indicating that the use of multiple approaches, including the analysis of the accessory genome, is needed to accurately elucidate the population dynamics of Listeria monocytogenes.

Draft Genome Sequence of Listeria monocytogenes Serovar 1/2a Strain IZSAM_Lm_14-16064, Isolated from an Italian Cooked Ham in 2014.

In this report, the draft genome sequence of Listeria monocytogenes serovar 1/2a strain IZSAM_Lm_14-16064, isolated in Italy from a cooked ham, is announced. The genome is similar to that of a clinical strain isolated in 2014.

Complete Genome Sequence of Chlamydia avium PV 4360/2, Isolated from a Feral Pigeon in Italy.

We report here the whole-genome sequence of a Chlamydia avium isolate recovered from a feral pigeon in 1999 in Italy. Only one complete genome of a C. avium strain has been published so far. Future comparative analyses could provide valuable insights on the genomic evolution of the pathogen.