Isolation of necrotoxigenic Escherichia coli from a dog with hemorrhagic pneumonia

Canine bufavirus (Carnivore protoparvovirus-3) infection in dogs with respiratory disease

Canine bufavirus (CBuV) or Carnivore protoparvovirus-3, a nonenveloped DNA virus belonging to the genus Protoparvovirus, family Parvoviridae, has been identified in dogs with respiratory and enteric diseases. Although CBuV detection has been reported in multiple countries, descriptions of pathologic findings associated with infection have not yet been provided. In this study, the authors necropsied 14 dogs (12 puppies and 2 adult dogs) from a breeding colony that died during multiple outbreaks of respiratory diseases. Postmortem investigations revealed extensive bronchointerstitial pneumonia with segmental type II pneumocyte hyperplasia in all necropsied puppies but less severe lesions in adults. With negative results of common pathogen detection by ancillary testing, CBuV DNA was identified in all investigated dogs using a polymerase chain reaction (PCR). Quantitative PCR demonstrated CBuV DNA in several tissues, and in situ hybridization (ISH) indicated CBuV tissue localization in the lung, tracheobronchial lymph node, and spinal cord, suggesting hematogenous spread. Dual CBuV ISH and cellular-specific immunohistochemistry were used to determine the cellular tropism of the virus in the lung and tracheobronchial lymph node, demonstrating viral localization in various cell types, including B-cells, macrophages, and type II pneumocytes, but not T-cells. Three complete CBuV sequences were successfully characterized and revealed that they clustered with the CBuV sequences obtained from dogs with respiratory disease in Hungary. No additional cases were identified in small numbers of healthy dogs. Although association of the bufavirus with enteric disease remains to be determined, a contributory role of CBuV in canine respiratory disease is possible.

Extraintestinal Pathogenic Escherichia Coli Causes Necrohemorrhagic Pneumonia in Multiple Research Dogs

Extraintestinal pathogenic Escherichia coli expressing cytotoxic necrotizing factor (CNF) 1 and 2 virulence factors is a rarely reported cause of acute, fatal necrohemorrhagic pneumonia in canines. A review of cases of necrohemorrhagic pneumonia in beagles at our facility between 2013 and 2021 revealed 21 dogs that died or were euthanized after acute onset lethargy, dyspnea, and hemorrhage. Some affected animals had recently been transported to the facility. In all dogs, lung lobes were discolored dark red and consolidated. Histologic lesions in 17 of these included alveolar necrosis, hemorrhage, edema, fibrin, acute inflammation, and intralesional colonies of bacilli. Lung was cultured for 10 dogs with E. coli isolated and CNF1 identified by virulence factor PCR in 7 of those. Based on these findings, extraintestinal E. coli should be considered an important cause of acute fatal necrohemorrhagic pneumonia in purpose-bred beagle research dogs and may be associated with a recent history of transport.

Molecular Characteristics, Ecology, and Zoonotic Potential of Escherichia coli Strains That Cause Hemorrhagic Pneumonia in Animals

Hemorrhagic pneumonia (HP) is a rare but highly lethal disease, mainly of dogs and cats, caused by hemolytic Escherichia coli strains that contain cnf1 (encoding cytotoxic necrotizing factor 1). After encountering fatal HP in two dogs, we used contemporary molecular methods, including multilocus sequence typing and whole-genome sequencing, to compare the corresponding case isolates with published HP clinical isolates and newly obtained fecal E. coli isolates from 20 humans and animals in the index HP case household. We also compared the aggregated HP clinical isolates, which represented 13 discrete strains, by pulsotype with a large, private pulsotype library of diverse-source E. coli. The HP clinical isolates represented a narrow range of phylogenetic group B2 lineages (mainly sequence types 12 and 127), O types (mainly O4 and O6), and H types (mainly H5 and H31), but diverse fimH alleles (type-1 fimbriae adhesin). Their extensive, highly conserved virulence genotypes, which qualified as extraintestinal pathogenic E. coli (ExPEC), encoded diverse adhesins, toxins, iron uptake systems, and protectins. Household surveillance identified multiple HP-like fecal strains, plus abundant between-host strain sharing, including of the household's index HP strain. The pulsotype library search identified, for five HP clinical strains, same-pulsotype human and animal fecal and clinical (predominantly urine) isolates, from diverse locales and time periods. Thus, E. coli strains that cause HP derive from a narrow range of ExPEC lineages within phylogroup B2, contain multiple virulence genes other than cnf1, are shared extensively between hosts, and likely function in nature mainly as intestinal colonizers and uropathogens. IMPORTANCE This study clarifies the clonal background and extensive virulence genotypes of the E. coli strains that cause hemorrhagic pneumonia in domestic animals (mainly dogs and cats), shows that such strains circulate among animals and humans, identifies a substantial intestinal colonization component to their lifestyle, and extends their known clinical manifestations to include bacteremia and urinary tract infection. The findings place these strains better into context vis-à-vis current understandings of E. coli phylogeny, ecology, and pathogenesis; identify questions for future research; and may prove relevant for surveillance and prevention efforts.

Fatal pneumonia caused by Extraintestinal Pathogenic Escherichia coli (ExPEC) in a juvenile cat recovered from an animal hoarding incident

The current study describes isolation of Extraintestinal Pathogenic Escherichia coli (ExPEC) from a juvenile male cat that died after being rescued from an animal hoarding incident. Grossly, there was evidence of pneumonia and renal abscessation. Histologically, there was diffuse interstitial pneumonia with necrosis and necrotizing and suppurative nephritis with colonies of coccobacilli. Within the lung, kidney, and mesentery there was necrotizing and suppurative vasculitis with thrombosis and coccobacilli. E. coli strain belonging to serotype O6:H1 that carried many of the virulence genes associated with ExPEC was isolated from the lung and kidney. The cat was part of a community of approximately 60 cats that lived in a house in a residential neighborhood, in which multiple cats had died. The case was of major significance to public health, as first responders, animal health professionals, and other community members were likely exposed to ExPEC, which is known to have zoonotic potential. It is important that pet owners, animal health and public health professionals, and first responders be made aware of the potential for zoonotic diseases.

Pathogenomics of the virulence plasmids of Escherichia coli

Bacterial plasmids are self-replicating, extrachromosomal elements that are key agents of change in microbial populations. They promote the dissemination of a variety of traits, including virulence, enhanced fitness, resistance to antimicrobial agents, and metabolism of rare substances. Escherichia coli, perhaps the most studied of microorganisms, has been found to possess a variety of plasmid types. Included among these are plasmids associated with virulence. Several types of E. coli virulence plasmids exist, including those essential for the virulence of enterotoxigenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterohemorrhagic E. coli, enteroaggregative E. coli, and extraintestinal pathogenic E. coli. Despite their diversity, these plasmids belong to a few plasmid backbones that present themselves in a conserved and syntenic manner. Thanks to some recent research, including sequence analysis of several representative plasmid genomes and molecular pathogenesis studies, the evolution of these virulence plasmids and the implications of their acquisition by E. coli are now better understood and appreciated. Here, work involving each of the E. coli virulence plasmid types is summarized, with the available plasmid genomic sequences for several E. coli pathotypes being compared in an effort to understand the evolution of these plasmid types and define their core and accessory components.

Necrotizing Pneumonia and Pleuritis Associated with Extraintestinal Pathogenic Escherichia Coli in a Tiger (Panthera Tigris) Cub

Extraintestinal pathogenic Escherichia coli (ExPEC) cause diseases in humans and animals, affecting organs outside the alimentary canal. In recent years, ExPEC have been reported as a cause of fatal pneumonia in dogs, cats, and in a horse. In the current report, a fatal case of pneumonia and pleuritis is described in a 4-week-old tiger ( Panthera tigris) cub associated with ExPEC. The cub was presented with a sudden-onset respiratory illness and died after a few hours. Postmortem examination of the cub revealed an acute necrotizing pneumonia. The alveolar spaces were filled with large numbers of inflammatory cells (predominantly macrophages), edema, fibrin strands, and short bacillary bacteria. Escherichia coli O6:H31 was isolated in pure culture from the affected lung. It carried virulence genes cnf-1, sfa, fim, hlyD, and papG allele III, which are known to be associated with ExPEC strains. No evidence of infection by any other agent was detected. This is the first report, to the authors' knowledge, in which ExPEC has been associated with pneumonia in tigers.

Extraintestinal pathogenic Escherichia coli-induced pneumonia in three kittens and fecal prevalence in a clinically healthy cohort population

Three kittens, ages 5, 9, and 17 weeks, were found dead by separate caregivers and were submitted for necropsy. At gross necropsy, each kitten had hemorrhagic or bloody fibrinoserous thoracic fluid and differing distributions of pulmonary consolidation. On histologic examination, the pulmonary lesion in each kitten was similar and was characterized by acute necrotizing and hemorrhagic pneumonia and pleuritis, with numerous intralesional small Gram-negative rods. A pure culture of a distinct serotype of Escherichia coli was identified in lung tissue from each kitten (O4H5, O6H7, O6H5). Lung isolates, genotyped by polymerase chain reaction, carried genes that are characteristic of extraintestinal pathogenic E. coli (ExPEC), including cnf-1, papG allele I, papA, papC, sfa, fim, hlyD, malX, iroN, fyuA, kpsMII, and ompT. Escherichia coli isolates from the intestines of 2 of the kittens were 100% related to the respective lung isolate, as determined by pulsed-field gel electrophoresis. Cultures of fecal samples collected from a clinically healthy cohort population of kittens revealed 16 of 19 tested kittens (84%) to be shedding hemolytic E. coli. Ten different serotypes were identified from 43 hemolytic E. coli fecal isolates from the cohort population, each of which had a genetic profile consistent with that typical of ExPEC. To the authors' knowledge, this is the first report to describe a cluster of isolated cases of pneumonia in kittens caused by distinct serotypes of ExPEC and to evaluate the prevalence of hemolytic E. coli carrying ExPEC-associated genes in the feces of a cohort population of kittens.

Bronchopneumonia associated with extraintestinal pathogenic Escherichia coli in a horse

Extraintestinal pathogenic Escherichia coli (ExPEC) strains carrying distinct virulence attributes are known to cause diseases in humans and animals and infect organs other than the gastrointestinal tract. A fatal case of bronchopneumonia in a 12-year-old female Quarterhorse was investigated. Following postmortem examination, E. coli, Enterococcus sp., and Klebsiella pneumonia were isolated from the lungs, which contained multifocal intra-alveolar accumulations of neutrophils and macrophages with edema, hemorrhage, and fibrin. The strain of E. coli belonged to O2H21 and carried virulence genes cnf1, sfa, foc, fimA, and papG allele I that are known to be associated with ExPEC strains. The strain was resistant to several antimicrobials including clindamycin, erythromycin, oxacillin, penicillin, and rifampin. This is the first report, to the authors' knowledge, in which ExPEC O2H21 has been associated with fatal bronchopneumonia in a horse.

Extraintestinal pathogenic Escherichia coli-induced acute necrotizing pneumonia in cats

Extraintestinal pathogenic Escherichia coli (ExPEC) are pathogens involved in several disease conditions, ranging from urinary tract infection to meningitis in humans and animals. They comprise epidemiologically and phylogenetically distinct strains, affecting most species and involving any organ or anatomical site. Here, we report fatal cases of necrotizing pneumonia in cats. Over a 1-week period, 13 cats from an animal shelter in Stamford, Connecticut were presented for necropsy. All had a clinical history of acute respiratory disease. The gross and microscopic findings for all the cats were consistent. Escherichia coli was uniformly isolated from the lungs of all the tested cats. All the isolates were haemolytic, genetically related as determined by enterobacterial repetitive intergenic consensus PCR, and harboured genes encoding for cytotoxic necrotizing factor-1 and fimbriae and adhesions that are characteristic of ExPEC, implying a point source clonal outbreak. As cats are common household pets, this report raises concerns regarding zoonotic potential (in either direction) for these ExPEC strains.

Differentiation of mesophilic and thermophilic bacteria with fourier transform infrared spectroscopy

In the present study the characterization and differentiation of mesophilic and thermophilic bacteria were investigated by using Fourier transform infrared (FT-IR) spectroscopy. Our results showed significant differences between the FT-IR spectra of mesophilic and thermophilic bacteria. The protein-to-lipid ratio was significantly higher for thermophiles compared to mesophiles. The absorption intensity of the CH(3) asymmetric stretching vibration was higher in thermophilic bacteria, indicating a change in the composition of the acyl chains. The higher intensity/area observed in the CH(2) symmetric stretching mode at 2857 cm(-1), and the CH(2) bending vibration band at 1452 cm(-1), indicated a higher amount of saturated lipids in thermophilic bacteria. The lipid C=O stretching vibration at 1739 cm(-1), which was observed in the mesophilic group, was not observed clearly in the thermophilic group, indicating a difference in packing that is presumably due to the decreased proportion of unsaturated acyl chains in thermophilic bacteria. In addition, the carbonyl groups become hydrogen bonded and the cellular DNA content was lower in thermophilic bacteria. Moreover, in the 1000-400 cm(-1) frequency region, the spectra of each bacterial species belonging to both the mesophilic and thermophilic bacterial groups, showed characteristic differences that were discriminated via dendrogram using cluster analysis. The current study implies that FT-IR spectroscopy could be successfully applied for the rapid comparison of bacterial groups and species to establish either similarities or discrepancies, as well as to confirm biochemical or physiological characteristics.