Bovine abortion associated with Nocardia farcinica

Diagnosis of bacteria from the CMNR group in farm animals

The CMNR group comprises bacteria of the genera Corynebacterium, Mycobacterium, Nocardia, and Rhodococcus and share cell wall and DNA content characteristics. Many pathogenic CMNR bacteria cause diseases such as mastitis, lymphadenitis, and pneumonia in farmed animals, which cause economic losses for breeders and represent a threat to public health. Traditional diagnosis in CMNR involves isolating target bacteria on general or selective media and conducting metabolic analyses with the assistance of laboratory biochemical identification systems. Advanced mass spectrometry may also support diagnosing these bacteria in the clinic's daily routine despite some challenges, such as the need for isolated bacteria. In difficult identification among some CMNR members, molecular methods using polymerase chain reaction (PCR) emerge as reliable options for correct specification that is sometimes achieved directly from clinical samples such as tracheobronchial aspirates and feces. On the other hand, immunological diagnostics such as the skin test or Enzyme-Linked Immunosorbent Assay (ELISA) for Mycobacterium tuberculosis yield promising results in subclinical infections with no bacterial growth involved. In this review, we present the methods most commonly used to diagnose pathogenic CMNR bacteria and discuss their advantages and limitations, as well as challenges and perspectives on adopting new technologies in diagnostics.

Case report: Pathology, antimicrobial resistance, and molecular characterization of bovine abortion cases caused by Nocardia farcinica in Korean native cattle

Introduction

Nocardia farcinica is an opportunistic bacterium that causes bovine mastitis and pulmonary, cutaneous, and central nervous system infections in humans. Bovine abortion caused by N. farcinica has been sporadically reported. The purpose of this study was to analyze the pathological findings of bovine abortions caused by N. farcinica in the Republic of Korea and determine the antimicrobial resistance and genotypical characteristics of N. farcinica isolates.

Case presentation

Three cases of bovine abortions were submitted to the Animal and Plant Quarantine Agency for differential diagnosis. Grossly, one fetus showed severe lung consolidation following palpation of the entire lobes. Histologically, necrotizing granulomatous interstitial pneumonia was observed in all fetuses; a fetus with a gross lesion demonstrated necrotizing lymphadenitis in the mesenteric lymph nodes and necrotizing dermatitis in the ear. N. farcinica isolates were isolated from the abomasal contents and lungs of all fetuses. Finally, two cases were diagnosed as abortions due to N. farcinica, and one was diagnosed as an N. farcinica abortion coinfected with bovine viral diarrhea virus. According to the multilocus sequence analysis, all isolates were identified as N. farcinica and were determined to be genetically related to isolates from humans. Two N. farcinica isolates were resistant to trimethoprim-sulfamethoxazole, which is recommended as the first treatment for human nocardial infections.

Conclusion

This is the first pathological report of bovine abortion caused by N. farcinica in the Republic of Korea. Further studies are needed to phenotypically and genotypically characterize N. farcinica isolates with various sources and continuously monitor antimicrobial resistance patterns.

Lumpy jaw caused by Nocardia farcinica in a Holstein cow

A 3-year-old Holstein cow was examined in an intensive system due to unilateral swelling in the mandible. A right mandibular mass was associated with painful mastication and Ptyalism. In palpation, the mass was raised, ulcerated, attached to the mandible bone and firm, approximately 17 × 12 × 10 cm3 in size. The lesion was sampled, and after routine bacteriology and histopathology procedures, the occurrence of lumpy jaw caused by Nocardia farcinica was confirmed. The bacterium was analysed using genome sequencing and new strain called Najm 114. Due to the risk of zoonosis of the isolated agent, the cow was euthanized. This is the first report of lumpy jaw caused by N. farcinica in a cow. This study showed that N. farcinica should be considered a possible etiological agent for lumpy jaw in cattle.

Nocardia farcinica abortion in a goat

A female goat fetus was received by the Colorado State University-Veterinary Diagnostic Laboratory following an isolated abortion of twins by a reportedly healthy doe. Postmortem examination did not reveal any gross abnormalities. Histologic evaluation revealed pyogranulomatous and necrotizing bronchopneumonia with intracellular and extracellular gram-positive and non-acid-fast filamentous bacilli. Aerobic culture of the stomach contents and pooled lung and liver tissue yielded light growth of Nocardia sp., which was identified by MALDI-TOF MS and 16s rDNA sequencing as Nocardia farcinica.

Nocardiosis in Free-Ranging Cetaceans from the Central-Eastern Atlantic Ocean and Contiguous Mediterranean Sea

We report the pathologic features of nocardiosis in five free-ranging delphinids from the Canary Islands and Andalusia, namely four striped dolphins (Stenella coerulealba) and one bottlenose dolphin (Tursiops truncatus). All animals had a multiorgan (disseminated) pattern of infection involving suppurative to pyogranulomatous and thromboembolic lesions in two or more organs. Most affected organs were (by decreasing order) lung, pulmonary lymph nodes, liver, kidney, adrenal glands, and central nervous system. Typical intralesional and intravascular branched and filamentous bacteria were highlighted by Grocott's methenamine silver and Gram stains. Bacterial analysis including 16S rRNA gene sequencing identified Nocardia farcinica in two striped dolphins and Nocardia otitidiscaviarum in one striped dolphin and the bottlenose dolphin. All dolphins tested (n = 4) for cetacean morbillivirus were negative; one dolphin had concurrent cutaneous herpesvirosis. These results provide the first record of N. otitidiscaviarum in cetaceans, the first account of N. farcinica in free-ranging dolphins, and confirmation of nocardiosis in central eastern Atlantic Ocean. These results expand the known geographic range of nocardiosis in cetaceans.

Nocardia cyriacigeogica from Bovine Mastitis Induced In vitro Apoptosis of Bovine Mammary Epithelial Cells via Activation of Mitochondrial-Caspase Pathway

Nocardia is one of the causing agents of bovine mastitis and increasing prevalence of nocardial mastitis in shape of serious outbreaks has been reported from many countries. However, the mechanisms by which this pathogen damages the bovine mammary epithelial cells (bMECs) is not yet studied. Therefore, this study was designed with the aim to evaluate the apoptotic effects elicited by Nocardia and to investigate the pathway by which the Nocardia induce apoptosis in bMECs. Clinical Nocardia cyriacigeorgica strain from bovine mastitis was used to infect the bMECs for different time intervals, viz. 1, 3, 6, 12, and 18 h, and then the induced effects on bMECs were studied using adhesion and invasion assays, release of lactate dehydrogenase (LDH), apoptosis analysis by annexin V and propidium iodide (PI) double staining, morphological, and ultrastructural observations under scanning electron microscope (SEM) and transmission electron microscope (TEM), mitochondrial transmembrane potential (ΔΨm) assay using flow cytometry, and the protein quantification of mitochondrial cytochrome c and caspase-9 and caspase-3 by western blotting. The results of this study showed that N. cyriacigeorgica possessed the abilities of adhesion and invasion to bMECs. N. cyriacigeorgica was found to collapse mitochondrial transmembrane potential, significantly (p < 0.05) release mitochondrial cytochrome c and ultimately induce cell apoptosis. Additionally, it promoted casepase-9 (p < 0.01) and casepase-3 (p < 0.05) levels, significantly (p < 0.01) increased the release of LDH and promoted DNA fragmentation which further confirmed the apoptosis. Furthermore, N. cyriacigeorgica induced apoptosis/necrosis manifested specific ultrastructure features under TEM, such as swollen endoplasmic reticulum, cristae degeneration, and swelling of mitochondria, vesicle formation on the cell surface, rupturing of cell membrane and nuclear membrane, clumping, fragmentation, and margination of chromatin. The present study is the first comprehensive insight into patho-morphological ultrastructural features of apoptosis/necrosis induced by N. cyriacigeorgica, which concluded that the clinical N. cyriacigeorgica induced apoptotic changes in the bMECs through mitochondrial-caspase dependent apoptotic pathway.