Characterization of streptococci and enterococci associated with septicaemia in broiler parents with a high prevalence of endocarditis

Case reports involving coinfection with Avibacterium paragallinarum and Ornithobacterium rhinotracheale in broiler chickens and Avibacterium endocarditis in broiler breeding hens in Poland

ABSTRACTThe study describes three clinical cases of infection with Avibacterium spp.. In case no. 1, respiratory clinical signs and high mortality (0.7-4.2% daily; total 21.2%) in Ross 308 broiler chickens were shown to be caused by coinfection with sequence type 9 of O. rhinotracheale presumptive serotype A and A. paragallinarum presumptive serotype B. The identical (pulsed-field gel electrophoresis) restriction pattern (pulsotype) of seven A. paragallinarum isolates indicated that infectious coryza in broilers was caused by the same clone. In cases 2 and 3, sudden increased deaths in Ross 308 broiler breeders (especially males) with lesions in the endocardium (valvular or mural endocarditis) were shown to be caused by A. endocarditis. Among nine antibiotics tested, florfenicol was the only antibiotic to which all A. paragallinarum and O. rhinotracheale isolates were susceptible. Out of the eight antibiotics tested, 11 A. endocarditis isolates from both clinical cases of infective endocarditis were susceptible to penicillin, amoxicillin, doxycycline and florfenicol. The A. endocarditis isolates tested in both clinical cases had different PFGE patterns (pulsotypes), but identical within a case. The causes of infectious coryza and infective endocarditis in the cases presented have not been determined. In the prevention of infectious diseases in large-scale livestock farming, it is very important to follow the rules of biosecurity.

Purine Metabolism and Hexosamine Biosynthetic Pathway Abnormalities in Diarrheal Weaned Piglets Identified Using Metabolomics

Post-weaning diarrhea significantly contributes to the high mortality in pig production, but the metabolic changes in weaned piglets with diarrhea remain unclear. This study aimed to identify the differential metabolites in the urine of diarrheal weaned piglets and those of healthy weaned piglets to reveal the metabolic changes associated with diarrhea in weaned piglets. Nine 25-day-old piglets with diarrhea scores above 16 and an average body weight of 5.41 ± 0.18 kg were selected for the diarrhea group. Corresponding to the body weight and sex of the diarrhea group, nine 25-month-old healthy piglets with similar sex and body weights of 5.49 ± 0.21 kg were selected as the control group. Results showed that the serum C-reactive protein and cortisol of piglets in the diarrhea group were higher than those in the control group (p < 0.05). The mRNA expression of TNF-α, IFN-γ in the jejunum and colon, and IL-1β in the jejunum were increased in diarrhea piglets (p < 0.05), accompanied by a reduction in the mRNA expression of ZO-1, ZO-2, and CLDN1 in the jejunum and colon (p < 0.05); mRNA expression of OCLN in the colon also occurred (p < 0.05). Metabolomic analysis of urine revealed increased levels of inosine, hypoxanthine, guanosine, deoxyinosin, glucosamine, glucosamine-1-p, N-Acetylmannosamine, chitobiose, and uric acid, identified as differential metabolites in diarrhea piglets compared to the controls. In summary, elevated weaning stress and inflammatory disease were associated with the abnormalities of purine metabolism and the hexosamine biosynthetic pathway of weaned piglets. This study additionally indicated the presence of energy metabolism-related diseases in diarrheal weaned piglets.

Virulence Mechanisms of Staphylococcal Animal Pathogens

Staphylococci are major causes of infections in mammals. Mammals are colonized by diverse staphylococcal species, often with moderate to strong host specificity, and colonization is a common source of infection. Staphylococcal infections of animals not only are of major importance for animal well-being but have considerable economic consequences, such as in the case of staphylococcal mastitis, which costs billions of dollars annually. Furthermore, pet animals can be temporary carriers of strains infectious to humans. Moreover, antimicrobial resistance is a great concern in livestock infections, as there is considerable antibiotic overuse, and resistant strains can be transferred to humans. With the number of working antibiotics continuously becoming smaller due to the concomitant spread of resistant strains, alternative approaches, such as anti-virulence, are increasingly being investigated to treat staphylococcal infections. For this, understanding the virulence mechanisms of animal staphylococcal pathogens is crucial. While many virulence factors have similar functions in humans as animals, there are increasingly frequent reports of host-specific virulence factors and mechanisms. Furthermore, we are only beginning to understand virulence mechanisms in animal-specific staphylococcal pathogens. This review gives an overview of animal infections caused by staphylococci and our knowledge about the virulence mechanisms involved.

Postmortem Evaluation of Cardiac Valvular Disease in Bald Eagles (Haliaeetus leucocephalus) and a Golden Eagle (Aquila chrysaetos)

Limited data are available regarding cardiac diseases in birds of prey despite their prevalence in these avian species. Literature regarding valvular lesions in birds of prey is scarce and includes single reports of left atrioventricular valvular endocarditis in an adult, free-ranging, male bald eagle (Haliaeetus leucocephalus) and aortic valvular endocarditis in an adult, free-ranging, female red-tailed hawk (Buteo jamaicensis). The purpose of this study was to evaluate the prevalence, signalment, gross necropsy findings, and histologic lesions of valvular lesions in eagles. In this retrospective study, necropsy reports for 24 free-ranging and captive eagles were evaluated over a 15-year period (July 3, 2006-February 28, 2021). Six (25%; 95% confidence interval: 8.9-58.9) birds, 5 bald eagles and 1 golden eagle (Aquila chrysaetos), met the inclusion criteria. Five (83.3%) of the 6 birds had valvular degeneration, 2 (33.3%) had endocarditis, and Staphylococcus aureus was cultured from 1 (16.7%) of the endocarditis cases. The 6 eagles with valvular lesions were all captive adults. Four of the birds were female (66.7%), and the aortic and left atrioventricular valves were equally affected. Acute or chronic cerebral infarcts were present in all 6 birds. Valvular cardiac disease should be considered as a differential diagnosis in eagles exhibiting respiratory distress, neurologic signs, syncope, or in cases of sudden death.

Disseminated Streptococcus gallinaceus infection. A new breed of zoonotic Streptococcus

Streptococcus gallinaceus is a new species of Streptococcus that was first isolated in 2004 in chickens. Infections in humans are associated with chicken exposure. There are very few case reports of human infections with this organism and none with disseminated infection. We report a case of Streptococcus gallinaceus bacteremia complicated by aortic valve endocarditis and lumbar osteomyelitis and paraspinal abscess in a patient with chicken exposure. The patient presented with progressive lower back pain and malaise. Blood culture was positive for Streptococcus gallinaceus. Magnetic resonance imaging (MRI) of the spine showed L2-L3 osteomyelitis with a compression fracture and paraspinal abscess. Transthoracic echocardiography revealed severe aortic insufficiency, 1-cm aortic valve echo density suspected to be a vegetation, and perforation of the right coronary cusp. He subsequently underwent anaortic valve repair. Pathology confirmed acute endocarditis with associated vegetations and granulation tissues. He was successfully treated with a six-week course of ceftriaxone.

Performance, Egg Quality, and Immunity of Laying Hens due to Natural Carotenoid Supplementation: A Meta-Analysis

This study aimed to investigate the effectiveness of carotenoid supplementation on the performance, egg quality, and immunity of laying hens using a meta-analysis approach. The database was searched using Google Scholar and Scopus, from 2012 to 2022. The literature was published in English. 47 Articles were selected for meta-analysis. Analyses were performed using the Open Meta-analyst for Ecology and Evolution (OpenMEE) software. The heterogeneity and data validation against publication bias were analyzed using JASP 0.16.2 software. Overall, the results showed that carotenoid supplementation improved feed intake by 0.32 g/day/hen [95% confidence interval (CI)=0.02 to 0.61], final body weight by 0.33 g/hen (95% CI=0.05 to 0.60), egg production by 0.38% (95% CI=0.14 to 0.63), egg weight by 0.29 g (95% CI=0.09 to 0.5), yolk colour by 2.11 (95% CI=1.71 to 2.51), Haugh unit (HU) by 0.26 (95% CI=0.11 to 0.42), yolk carotenoids by 1.17 μg/kg (95% CI=0.59 to 1.75), immunoglobulin A (IgA) by 0.74 mg/L (95% CI=0.18 to 1.29), and lower yolk cholesterol by -0.38 mg/g (95% CI=-0.59 to -0.16). Feed conversion ratio (FCR), eggshell thickness, and white blood cells were unaffected by the application of carotenoids. The heterogeneity analysis showed variability in all studies (<0.05). In conclusion, carotenoid supplementation can elevate productivity, enhance egg quality, and improve immunity. However, based on Kendall's test, there was a publication bias in several parameters, namely FCR, egg weight, HU, yolk carotenoids, and IgA.

Pyogranulomatous dermatitis with Enterococcus faecalis in a spotted seal (Phoca larga)

BACKGROUND

Cutaneous infections are important diseases in captive and free-ranging pinnipeds and are associated with various causative agents. Some special agents, such as fungi, morbillivirus and mycobacteria, can cause cutaneous specific granulomatous inflammation.

OBJECTIVES

To identity the cause of chronic dermatitis in a spotted seal in an aquarium.

METHODS

Herein, we analyze the clinical history and cutaneous samples of the spotted seal through differential diagnosis (histopathology, microorganism culture, special histochemical staining methods, PCR), and antibiotic susceptibility test.

RESULTS

This is a rare pyogranulomatous dermatitis case caused by E. faecalis in a captive adult male spotted seal (Phoca largha) in an aquarium.

CONCLUSIONS

We provide a meaningful approach to the diagnosis and treatment of bacterial dermatitis in pinnipeds.

Characterization of Escherichia coli and other bacteria isolated from condemned broilers at a Danish abattoir

Meat inspection is important to ensure food safety and protect public health. Visual inspection of slaughtered carcasses for pathological changes should be supported by bacteriological analysis to determine whether the entire carcass or parts of it should be condemned. The aim of this study was to determine the bacterial species present in different sample types from condemned broiler carcasses. Furthermore, we investigated the genetic characteristics, zoonotic potential, and relatedness of Escherichia coli, the predominant bacterial species isolated from the carcasses. A total of 400 broiler carcasses condemned because of cellulitis (100), scratches (100), hepatitis (100), and healthy control carcasses (100) were selected. Samples of meat, pathological lesion, and bone marrow of each carcass were obtained for microbial analysis. From the analyzed samples, 469 bacterial isolates were recovered with E. coli accounting for 45.8%, followed by Aeromonas spp. (27.9%), in particular A. veronii. The highest rate of bacterial isolation was observed in carcasses condemned with cellulitis, whereas carcasses with hepatitis had the lowest rate of bacterial isolation. Forty-four E. coli isolates originating from different sample types were selected for whole genome sequencing. A clonal relationship was shown between E. coli from different sample types of the same carcass condemned with cellulitis and scratches. A major clade of E. coli was found in carcasses condemned with cellulitis with isolates containing mdf(A), tet(A), and bla TEM-1B genes that confer resistance to macrolides, tetracycline, and ampicillin, respectively. E. coli in this clade all belonged to ST117 and clustered with E. coli isolates previously collected from dead chickens and carcasses condemned due to cellulitis in Denmark, Finland, and the United Kingdom. Bacterial evaluation results of carcasses condemned with cellulitis, scratches (moderate to severe skin lesion), and acute hepatitis confirmed the need for total condemnation of carcasses with these pathological findings. A similar evaluation should be done for carcasses affected with chronic hepatitis, and minor scratches lesions.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial-resistant Enterococcus faecalis in poultry

Enterococcus faecalis (E. faecalis) was identified among the most relevant antimicrobial-resistant (AMR) bacteria in the EU for poultry in a previous scientific opinion. Thus, it has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as in Article 9 and Article 8 for listing animal species related to the bacterium. The assessment has been performed following a methodology previously published. The outcome is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with uncertain outcome. According to the assessment here performed, it is uncertain whether AMR E. faecalis can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (33-66% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that the bacterium does not meet the criteria in Sections 1, 2 and 4 (Categories A, B and D; 0-5%, 5-10% and 1-10% probability of meeting the criteria, respectively) and the AHAW Panel is uncertain whether it meets the criteria in Sections 3 and 5 (Categories C and E, 33-66% and 33-66% probability of meeting the criteria, respectively). The animal species to be listed for AMR E. faecalis according to Article 8 criteria are mostly birds of the orders Galliformes and Anseriformes, but also mammals and reptiles can serve as reservoirs.

Migratory birds travelling to Bangladesh are potential carriers of multi-drug resistant Enterococcus spp., Salmonella spp., and Vibrio spp

Antimicrobial resistance (AMR) is a major health crisis globally. Migratory birds could be a potential source for antibiotic resistant (ABR) bacteria. Not much is known about their role in the transmission of ABR in Bangladesh. In this study, a total of 66 freshly dropped fecal materials of migratory birds were analyzed. Bacterial isolation and identification were based on cultural properties, biochemical tests, and polymerase chain reaction (PCR). The disk diffusion method was employed to evaluate antibiogram profiles. By PCR, out of 66 samples, the detection rate of Enterococcus spp. (60.61%; 95% confidence interval: 48.55-71.50%) was found significantly higher than Salmonella spp. (21.21%; 95% CI: 13.08-32.51%) and Vibrio spp. (39.40%; 95% CI: 28.50-51.45%). Enterococcus isolates were frequently found resistant (100-40%) to ampicillin, streptomycin, meropenem, erythromycin, and gentamicin; Salmonella isolates were frequently resistant (72-43%) to chloramphenicol, tetracycline, ampicillin, streptomycin, and erythromycin; and Vibrio spp. isolates were frequently resistant (77-31%) to vancomycin, ampicillin, erythromycin, tetracycline, and streptomycin. In addition, 60% (95% CI: 44.60-73.65%) Enterococcus spp., 85.71% (95% CI: 60.06-97.46%) Salmonella spp., and 76.92% (95% CI: 57.95-88.97%) Vibrio spp. isolates were multi-drug resistant (MDR) in nature. Three isolates (one from each bacterium) were found resistant against six classes of antibiotics. The bivariate analysis revealed strong associations (both positive and negative) between several antibiotic pairs which were resistant to isolated organisms. To the best of our knowledge, this is the first study in detecting MDR Enterococcus spp., Salmonella spp., and Vibrio spp. from migratory birds travelling to Bangladesh. Frequent detection of MDR bacteria from migratory birds travelling to Bangladesh suggests that these birds have the potential to carry and spread ABR bacteria and could implicate potential risks to public health. We recommend that these birds should be kept under an AMR surveillance program to minimize the potential risk of contamination of the environment with ABR as well as to reduce their hazardous impacts on health.

A Review of Current Knowledge on Staphylococcus agnetis in Poultry

Simple Summary

This literature review provides a synthesis and evaluation of the current knowledge on Staphylococcus agnetis (S. agnetis) and its implications in poultry pathology. Recent studies revealed that S. agnetis can cause bacterial chondronecrosis with osteomyelitis (BCO), endocarditis, and septicemia in broiler chickens. Lameness constitutes one of the major health and welfare problems causing huge economic losses in the poultry industry. To date, a range of infectious and non-infectious factors have been associated with lameness in poultry. Among bacteria of the genus Staphylococcus, Staphylococcus aureus is the main species associated with locomotor problems. This contrasts with S. agnetis, which until recently had not been considered as a poultry pathogen. Previously only reported in cattle, S. agnetis has expanded its host range to chickens, and due to its unique characteristics has become recognized as a new emerging pathogen. The genotypic and phenotypic similarities between S. agnetis and other two staphylococci (S. hyicus and S. chromogenes) make this pathogen capable of escaping recognition due to misidentification. Although a significant amount of research on S. agnetis has been conducted, many facts about this novel species are still unknown and further studies are required to understand its full significance in poultry pathology.

Abstract

This review aims to summarize recent discoveries and advancements regarding the characteristics of Staphylococcus agnetis (S. agnetis) and its role in poultry pathology. S. agnetis is an emerging pathogen that was primarily associated with mastitis in dairy cattle. After a presumed host jump from cattle to poultry, it was identified as a pathological agent in broiler chickens (Gallus gallus domesticus), causing lameness induced by bacterial chondronecrosis with osteomyelitis (BCO), septicemia, and valvular endocarditis. Economic and welfare losses caused by lameness are global problems in the poultry industry, and S. agnetis has been shown to have a potential to induce high incidences of lameness in broiler chickens. S. agnetis exhibits a distinct repertoire of virulence factors found in many different staphylococci. It is closely related to S. hyicus and S. chromogenes, hence infections caused by S. agnetis may be misdiagnosed or even undiagnosed. As there are very few reports on S. agnetis in poultry, many facts about its pathogenesis, epidemiology, routes of transmission, and the potential impacts on the poultry industry remain unknown.

Multidrug Resistance (MDR) and Collateral Sensitivity in Bacteria, with Special Attention to Genetic and Evolutionary Aspects and to the Perspectives of Antimicrobial Peptides-A Review

Antibiotic poly-resistance (multidrug-, extreme-, and pan-drug resistance) is controlled by adaptive evolution. Darwinian and Lamarckian interpretations of resistance evolution are discussed. Arguments for, and against, pessimistic forecasts on a fatal “post-antibiotic era” are evaluated. In commensal niches, the appearance of a new antibiotic resistance often reduces fitness, but compensatory mutations may counteract this tendency. The appearance of new antibiotic resistance is frequently accompanied by a collateral sensitivity to other resistances. Organisms with an expanding open pan-genome, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae, can withstand an increased number of resistances by exploiting their evolutionary plasticity and disseminating clonally or poly-clonally. Multidrug-resistant pathogen clones can become predominant under antibiotic stress conditions but, under the influence of negative frequency-dependent selection, are prevented from rising to dominance in a population in a commensal niche. Antimicrobial peptides have a great potential to combat multidrug resistance, since antibiotic-resistant bacteria have shown a high frequency of collateral sensitivity to antimicrobial peptides. In addition, the mobility patterns of antibiotic resistance, and antimicrobial peptide resistance, genes are completely different. The integron trade in commensal niches is fortunately limited by the species-specificity of resistance genes. Hence, we theorize that the suggested post-antibiotic era has not yet come, and indeed might never come.

Vegetative Endocarditis due to Staphylococcus aureus in an Umbrella Cockatoo (Cacatua alba)

A 15-year-old, female cockatoo (Cacatua alba) was presented with a history of intermittent cloacal prolapse of 1-year duration. After each prolapse, the owner would digitally reduce the distended cloacal tissue within approximately 12-24 hours, for short-term resolution. The cockatoo was examined 3 times over a 7-month period and received supportive care with leuprolide acetate, behavioral modification, and diet change. After the third examination, the owner decided to proceed with a surgical cloacopexy. Five days after the last examination and before the procedure was scheduled, the cockatoo was reexamined for acute onset of weakness, anorexia, lethargy, and right-leg paresis. Despite supportive treatment, the cockatoo's clinical condition declined, and it went into respiratory arrest. Resuscitative efforts, including manual ventilation and cardiovascular support, were unsuccessful, and the bird died. Results of postmortem examination revealed vegetative endocarditis with intralesional bacteria cultured as Staphylococcus aureus, right-hindlimb myonecrosis, hepatitis, and nephritis. We suspect that the source of the hematogenous S aureus infection in this cockatoo was translocation from the owner's skin from the repeated manual manipulation and replacement of the prolapsed cloacal tissue.

The application of the loop-mediated isothermal amplification (LAMP) method for diagnosing Enterococcus hirae-associated endocarditis outbreaks in chickens

BACKGROUND

Enterococcus hirae is considered a part of the normal intestinal biota of several domestic animals, including poultry. However, this species is also associated with infective endocarditis in chickens, a disease that leads to unexpected deaths and serious economical losses. Enterococcus hirae is identified predominantly with the use of conventional bacteriological methods, biochemical tests and PCR. Rapid, sensitive and specific methods for detecting E. hirae in clinical samples are required in poultry production. The aim of this study was to use the Loop-Mediated Isothermal Amplification (LAMP) for the identification and quantification of E. hirae in heart samples from broiler chickens.

RESULTS

The specificity of the LAMP method was confirmed for 7 enterococcal strains and 3 non-enterococcal strains. E. hirae was detected in all of the 22 analyzed clinical bacterial isolates and in all of the 9 heart samples. Three sets of primers supported the detection of E. hirae with high sensitivity and specificity within one hour. The highest detection rate of a LAMP product was approximately 7 min for an E. hirae strain and 12 min for a positive heart sample. The detection limit for the E. hirae ATCC 10541 standard was 1.3 × 10² CFU (43.4 fg) or 13.8 copies of the E. hirae genome equivalent per reaction. The reaction was 10-fold more sensitive than conventional species-specific PCR. The LAMP assay supported the determination of the E. hirae load in chicken hearts with endocarditis in field cases. The average number of E. hirae cells in hearts was 5.19 × 10⁷ CFU/g of tissue, and the average number of E. hirae genome equivalents in hearts was 5.51× 10⁶ copies/g of tissue. Bacterial counts were significantly higher in the LAMP assay than in the standard plate count.

CONCLUSIONS

The LAMP assay is a useful diagnostic tool and an effective alternative to conventional methods for the detection of this enterococcal species. The sodA-based LAMP assay supported direct identification of E. hirae from pure cultures and heart samples without previous bacterial cultivation. This is the first study to apply the LAMP method for the purpose of diagnosing E. hirae-associated endocarditis in poultry.

ISOLATION OF STREPTOCOCCI FROM A FATAL CASE OF MYOCARDITIS IN A CAPTIVE BROWN BEAR (URSUS ARCTOS)

A 10-yr-old, male brown bear ( Ursus arctos ) from Bursa Zoo in Turkey died without any apparent signs. Severe purulent pericarditis and myocarditis with mild ascites, lung edema, and moderate liver congestion were observed during necropsy. Microscopically, there were severe neutrophilic infiltrations in the myocardium and thoracic lymph nodes. A member of the Streptococcus bovis - Streptococcus equinus complex (SBSEC) was isolated and identified phenotypically.

PIMMS (Pragmatic Insertional Mutation Mapping System) Laboratory Methodology a Readily Accessible Tool for Identification of Essential Genes in Streptococcus

The Pragmatic Insertional Mutation Mapping (PIMMS) laboratory protocol was developed alongside various bioinformatics packages (Blanchard et al., 2015) to enable detection of essential and conditionally essential genes in Streptococcus and related bacteria. This extended the methodology commonly used to locate insertional mutations in individual mutants to the analysis of mutations in populations of bacteria. In Streptococcus uberis, a pyogenic Streptococcus associated with intramammary infection and mastitis in ruminants, the mutagen pGhost9:ISS1 was shown to integrate across the entire genome. Analysis of >80,000 mutations revealed 196 coding sequences, which were not be mutated and a further 67 where mutation only occurred beyond the 90th percentile of the coding sequence. These sequences showed good concordance with sequences within the database of essential genes and typically matched sequences known to be associated with basic cellular functions. Due to the broad utility of this mutagen and the simplicity of the methodology it is anticipated that PIMMS will be of value to a wide range of laboratories in functional genomic analysis of a wide range of Gram positive bacteria (Streptococcus, Enterococcus, and Lactococcus) of medical, veterinary, and industrial significance.

Staphylococcus simulans associated with endocarditis in broiler chickens

This report suggests a strong association between coagulase-negative Staphylococcus simulans and endocarditis in broiler chickens of a single flock. Clinical signs included increased mortality and lameness, and some dead chickens were found on their backs. Lesions included cauliflower-like, fibrinous vegetative lesions on the left atrioventricular valve; cream-coloured, necrotic foci of varying size in the liver; and necrosis of the femoral head. Histopathological examination of the heart revealed multifocal conglomerates of bacterial colonies attached to the valvular endocardium, threads of fibrin, and inflammatory cells with the presence of heterophils. S. simulans strains were first identified by API ID32, and then confirmed with Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry and by partial sequencing of the rpoB and dnaJ genes. These bacteria were resistant to methicillin but sensitive to vancomycin and characterized by slime production and protease activity.

Pathology and localization of Avibacterium endocarditidis in experimentally infected broiler breeders

The aim of this study was to investigate the pathogenic potential of Avibacterium endocarditidis. Forty broiler breeders were inoculated with one of three doses of the organism and killed at different time points. Bacteriology, pathology and fluorescence in-situ hybridization (FISH) were performed to evaluate bacterial growth and the development of lesions. Abundant growth in pure culture of A. endocarditidis was always obtained from valvular lesions, while only poor growth or no growth was obtained from liver and spleen lesions, confirming previous observations from naturally occurring cases. Gross lesions and histopathological findings confirmed previous observations. Valvular lesions were acute, ranging from slight thickening of the valves to severe inflammation. In most cases, bacteria colonized the valves. Lesions observed in the spleen included different degrees of necrosis and liver lesions ranged from very small infarcts to large areas of coagulative necrosis. Arthritis occurred in 19 birds, 15 of which tested positive for A. endocarditidis. Most birds developed bacteraemia, but the inability to isolate bacteria from the liver and spleen and the lack of bacteria demonstrated by FISH and histopathology, suggested lack of fulminant septicaemia. A significant correlation between the size of dose inoculated and development of valvular endocarditis was not observed; however, regressive changes in the ovary, liver necrosis and hepato-, spleno- and renomegaly were significantly dose dependent. A. endocarditidis represents a potential pathogen for chickens, the reservoir of which remains to be determined.

Co-infection of Ornithobacterium rhinotracheale with Streptococcus zooepidemicus in chickens

An outbreak of bronchial embolization with 50%-70% morbidity and 30% mortality occurred in broilers in northeast China. This highly contagious disease is characterized by the sudden onset of clinical symptoms, including dyspnea, hemorrhagic tracheal discharge, and bronchial obstruction. Subsequently, six strains of Ornithobacterium rhinotracheale (ORT) and three strains of Streptococcus zooepidemicus were isolated from the various organs and identified using biochemical tests and PCR methods. The pathogenesis of embolization in chickens is poorly understood. The current experimental study confirmed that ORT infection alone could induce a significantly fatal hemorrhagic pneumonia and high mortality in comparison with S. zooepidemicus infection. Moreover, co-infection of ORT with S. zooepidemicus could induce even higher mortality, with severe bronchial obstruction, than that observed in chickens infected with S. zooepidemicus or ORT alone. Therefore, the combination of ORT and S. zooepidemicus may be associated with the outbreak of chicken bronchial embolization. Further investigation of the pathogenesis of ORT and Streptococcus is urgently needed.

A major outbreak of Streptococcus equi subsp. zooepidemicus infections in free-range chickens is linked to horses

Infections of poultry due to Streptococcus equi subsp. zooepidemicus have been rare during the past decades and dissimilarities have been reported as to symptoms and lesions; likewise, the source of serious outbreaks has remained speculative. An outbreak affecting 11,000 free-range chickens at the age of 47 wk is reported. The outbreak manifested itself as acute at the onset and was followed by a chronic stage, resulting in some 80% mortality within 21 wk. Small-colony variants (SCVs) of S. equi subsp. zooepidemicus associated with the chronic phase are reported for the first time, and it is discussed whether SCVs might explain the change in lesions observed. Comparison of partial sequences of rpoB, multilocus sequence typing, and pulsed-field gel electrophoresis of isolates from chickens and horses kept at the farm showed the isolates to be identical and horses a likely source of infection. The present findings underline the importance of protecting free-range chickens from contact with other animals and birds known to host pathogens of importance to poultry.

Molecular characterization of vanA-containing Enterococcus from migratory birds: song thrush (Turdus philomelos)

Vancomycin-resistant enterococci (VRE) were detected in two faecal samples (1.3%) of song thrush in Portugal. vanA isolates showed high level vancomycin/teicoplanin resistance, as well as resistance to ciprofloxacin, quinupristin-dalfopristin and cloranfenicol. Thrush can be a reservoir of VRE and transmit these resistant bacteria to other animals including humans.

An investigation on first-week mortality in layers

The quality of day-old chick placement and management upon arrival have a major impact on first-week mortality (FWM) and subsequent welfare in layers. The present study investigated FWM and causes of FWM in 50 flocks of layers. Post mortem results from 983 chickens showed that 50% died from infections, whereas noninfectious causes, in particular dehydration and nephropathy with visceral gout, made up the remaining causes of mortality. Escherichia coli and Enterococcus faecalis were identified as the most significant bacterial pathogens associated with FWM. Statistical analysis demonstrated a significant correlation between FWM and total mortality during rearing, and a model predicting total mortality in the rearing period based on FWM was established. A statistically significant correlation between FWM and uniformity of the flock was not demonstrated at 1-2 wk of age or at approximately 15 wk of age. Genetic characterization of E. coli and E. faecalis provided evidence for a polyclonal nature of these infections in affected flocks, indicating different sources of infection. Results obtained underline the importance of minimizing FWM to a level less than 1%.

Multilocus sequence typing of Enterococcus faecalis isolates demonstrating different lesion types in broiler breeders

A total of 69 isolates of Enterococcus faecalis from broiler breeders demonstrating different lesion types and representing eight different flocks were characterized by multilocus sequence typing. Twenty isolates obtained from healthy birds representing two additional flocks were included for comparison. A total of 12 different sequence types (STs) was obtained. Correlation between ST and lesion type was not demonstrated. However, three STs (ST82, ST174, ST177) made up 81% of the isolates associated with lesions, indicating that these STs might be particularly associated with birds. In addition, ST174, the most frequently demonstrated ST, was only obtained from affected birds. Surprisingly, ST82, previously reported to be associated with amyloid arthropathy in layers worldwide, demonstrated a high degree of diversity as to lesion types, just as healthy carriers were demonstrated among broiler breeders. STs associated with healthy birds and lesions, respectively, did not demonstrate a phylogenetic relationship.

Enterococcus hirae-associated endocarditis outbreaks in broiler flocks: clinical and pathological characteristics and molecular epidemiology

BACKGROUND

Enterococcus hirae-associated endocarditis, characterized by a peak in mortality during the second week of the grow-out, and occasionally lameness, was diagnosed at Dutch broiler farms.

OBJECTIVES

Field cases were studied to increase knowledge on clinical and pathological characteristics, pathogenesis and epidemiology of these infections.

ANIMALS AND METHODS

In total, 1266 birds of 25 flocks from 12 farms were examined. Post-mortem examinations, bacteriology, histopathology, PCR and DNA fingerprinting was carried out. Six flocks were followed longitudinally (n = 1017 birds).

RESULTS

Average mortality was 4.1% for the entire grow-out, of which 36% was attributed to endocarditis. Fibrinous thromboendocarditis of the right atrioventricular (AV) valve was found in 24% of hearts, compared to 7% and 4% with lesions of left and both AV valves, respectively. Thrombotic lesions were found in 24% (n = 432) of lungs, but only in larger branches of the Arteria pulmonalis. Occasionally, thrombi were found in the Arteria ischiadica externa and in liver and brain vessels. Enterococcus was cultured from 54% (n = 176) of heart and in 75% (n = 28), 62% (n = 106) and 31% (n = 16) of liver, bone marrow and lung samples, respectively. Further identification, using the Rapid ID Strep 32 API system and a PCR targeting mur-2 and mur-2(ed) genes was carried out on a subset of Enterococcus positive isolates (n = 65): both techniques identified the isolates as Enterococcus hirae. Pulsed-field gel electrophoresis did not indicate evidence of clonality between farms and flocks.

CONCLUSIONS

The relevance of these findings for pathogenesis and epidemiology of E. hirae infections is discussed. CLINICAL IMPORTANCE. This study may facilitate diagnosis of field cases and may contribute to the design of further research and development of control measures.

Observations on the incidence and aetiology of valvular endocarditis in broiler breeders and detection of a newly described taxon of Pasteurellaceae, Avibacterium endocarditidis

A total of 122 dead broiler breeders randomly selected from a flock showing normal production parameters and covering the age from 44 to 61 weeks were subjected to a comprehensive routine post-mortem examination including examination for lesions of endocarditis. Forty-two hens (34%) showed valvular endocarditis caused by Avibacterium endocarditidis (43%), Enterococcus faecalis (31%), Staphylococcus aureus (5%) and Streptococcus pluranimalium (5%), while growth was not obtained from 17% with the methods used for isolation. Gross lesions associated with the different bacterial pathogens did not allow separation according to pathogens involved. Port of entry and pathogenesis associated with the high prevalence of valvular endocarditis remained speculative. The present findings demonstrated the newly described species of Pasteurellaceae, Avibacterium endocarditidis associated with endocarditis in chickens and confirm previous observations on the prevalence of endocarditis in chickens, partly explaining the slightly increased mortality normally observed in broiler breeders during the last weeks of production.

An investigation of the pathology and pathogens associated with porcine respiratory disease complex in Denmark

Respiratory infections are among the most important diseases of growing pigs. In order to elucidate the multifactorial aetiology of porcine respiratory disease complex (PRDC) in Denmark, lungs from 148 finishing pigs with cranioventral bronchopneumonia (case group) and 60 pigs without lung lesions (control group) were collected from abattoirs. The pathogens involved in PRDC and their interactions were identified and linked to the histopathological diagnosis. The lung samples were cultured for bacteria and tested by multiplex polymerase chain reaction for presence of swine influenza virus (type A), porcine reproductive and respiratory syndrome virus (both European and US type), porcine circovirus type 2 (PCV2), porcine respiratory coronavirus, porcine cytomegalovirus, Mycoplasma hyopneumoniae and Mycoplasma hyorhinis. All cases had cranioventral lobular bronchopneumonia consistent with PRDC. There was a broad range of microscopical lesions and the cases were characterized as acute (n = 10), subacute (n = 24) or chronic (n = 114) bronchopneumonia. Five bacterial species, five viruses and two Mycoplasma spp. were detected in different combinations. PCV2, M. hyopneumoniae, M. hyorhinis and Pasteurella multocida were detected most frequently among the PRDC affected swine and the diversity and number of pathogens were higher in these animals compared with controls. No clear-cut associations were detected between pathogens and histological lesions or histopathological diagnoses. PRDC occurs more frequently than enzootic pneumonia among Danish finishing pigs and has complex and varied histopathology.

Association of Streptococcus pluranimalium with valvular endocarditis and septicaemia in adult broiler parents

The genus Streptococcus consists of more than 60 species, but only Streptococcus equi subspecies zooepidemicus, Streptococcus gallolyticus ssp. gallolyticus, Streptococcus gallinaceus, Streptococcus dysgalactiae, Streptococcus mutans and Streptococcus suis have been isolated from poultry. During investigations of the aetiology of increased mortality in broiler parent stock at the end of production, pure cultures of streptococcal-like organisms that could not be classified among these six species were obtained from 24 cases of septicaemia or valvular endocarditis and septicaemia. Phenotypic characterization using the API20 STREP kit identified the isolates as Aerococcus viridans (10), Aerococcus urinae (2), Leuconostoc species (4), Streptococcus salivarius (2), Streptococcus bovis II 3 (1), Enterococcus avium (3), Enterococcus faecium (1) or Gemella morbillorum (1). However, this identification was misleading as subsequent genetic investigations using pulse field gel electrophoresis and sequencing of 16S rRNA genes showed that 19 isolates were classified as Streptococcus pluranimalium, while the remaining isolates were E. avium (3), E. faecium (1) or Lactobacillus species (1). Misidentification by API20 STREP was related to the database provided by the manufacturer, as the phenotypic characteristics could identify these organisms as S. pluranimalium. The isolates of S. pluranimalium belonged to at least three different clones as determined by pulsed field gel electrophoresis of SmaI-digested genomic DNA. The capacity that these isolates had to colonize the valvular endothelium was suggested by the occurrence of valvular endocarditis in 12 of 19 cases. Demonstration of the same clone in all four houses on a farm suggested the pathogenic potential of this organism.

High prevalence of tetracycline resistance in Enterococcus isolates from broilers carrying the erm(B) gene

A total of 73 isolates of Enterococcus spp. carrying the erm(B) gene were obtained from cloacal swabs of broiler chickens derived from 13 different farms in Belgium. The erm(B) gene encodes resistance to macrolides, lincosamides and streptogramin B antibiotics (MLS(B)). The isolates belonged to eight different species: Enterococcus avium (eight isolates), Enterococcus casseliflavus (11 isolates), Enterococcus cecorum (eight isolates), Enterococcus durans (seven isolates), Enterococcus faecalis (10 isolates), Enterococcus faecium (17 isolates), Enterococcus gallinarum (seven isolates) and Enterococcus hirae (five isolates). Acquired resistance to tetracycline was detected in 68 of the isolates, and in 62 of these it was associated with the presence of the resistance genes tet(L), tet(M), tet(O) or tet(S). In three E. faecium isolates that were phenotypically susceptible to tetracycline, tet(L) or tet(M) was present. The transposon integrase gene (int gene) of the Tn916/Tn1545 transposon family was detected in 18 of the 54 isolates that contained the tet(M) gene. It was concluded that acquired resistance to tetracycline antibiotics is often present in enterococci from poultry carrying the erm(B) gene. The use of tetracyclines in poultry may therefore co-select for resistance to MLS(B) antibiotics, which may be important as alternative therapy for enterococcal infections in humans.

Streptococcus gallinaceus bacteraemia in an abattoir worker presenting with a febrile illness

Streptococcus gallinaceus is a newly described species of viridans streptococci, previously only identified as causing disease in broiler chickens. This organism was recovered in pure culture from blood taken from a New Zealand abattoir worker presenting with a febrile illness. This first report of bacteraemia caused by S. gallinaceus in a human may help the understanding of the ecology of this recently described organism.

Reproduction of sepsis and endocarditis by experimental infection of chickens with Streptococcus gallinaceus and Enterococcus hirae

This study describes experimental infections in 4-week-old chickens inoculated intravenously with approximately 10(8) colony-forming units Streptococcus gallinaceus strain CCUG 42692T (C13156) or Enterococcus hirae strain DSM 20160 (C17410). Birds were necropsied following death and obvious clinical signs of disease or were euthanized weekly after infection for up to 4 weeks. At necropsy, lesions included splenomegaly, hepatomegaly, valvular and/or mural endocarditis. Cardiac lesions included focal necrotizing myocarditis and/or yellow-white vegetative valvular endocarditis or greyish proliferations associated with the mitral valves in 35% (6/20) and 79% (19/24) of birds infected with S. gallinaceus and in 20% (4/20) and 55% (12/22) of birds infected with E. hirae via the brachial and jugular veins, respectively. S. gallinaceus was reisolated from heart valves in 45% (9/20) and 75% (18/24) and E. hirae in 35% (7/20) and 73% (16/22) after inoculation via brachial and jugular veins, respectively. Both challenge strains were also isolated from liver, spleen, bone marrow and hock joints. A significant difference between the infections with the two strains was seen only with reisolation of E. hirae from hock joints (P < 0.007). Significant differences were apparent between the two inoculation routes only with E. hirae, where infection via the jugular vein was associated with higher culture positive isolations from the heart (P = 0.029), bone marrow (P = 0.002) and hock joints (P < 0.001) compared with the brachial vein. Birds injected with sterile phosphate-buffered saline were negative for culture of the challenge strains and no lesions were observed in these controls. The results confirm that both S. gallinaceus and E. hirae can cause endocarditis in experimentally infected chickens.