Amplified 16S ribosomal DNA restriction analysis for identification of Avibacterium paragallinarum

Pathogenic Microbial Profile and Antibiotic Resistance Associated with Periodontitis

Abstract

Phenotyping based on conventional microbiological, physiological, and molecular analysis by using ARDRA technique was developed with the aim to assess the pathogenic microbial load associated with different stages of the periodontal disease. In addition, in the face of the global issue of antimicrobial resistance, the isolated bacterial strains were evaluated for their antibiotic susceptibility profile. The pathogenic bacterial community was predominantly of Gram-negative strains (66.66%). The most common species were Citrobacter freundii, Bacillus sp., Raoutella sp., Klebsiella ozaenae and Pseudomonas sp. However, except for the healthy control group, Staphylococcus spp. was isolated from all stages of periodontitis. Multidrug resistance to beta-lactam antibiotics was observed for Streptococcus pneumoniae, Raoutella sp. and Enterococcus avium. Here, we verify a statistically significant relationship between periodontitis stages and the diversity of the bacterial community. Patients with periodontitis showed a more diverse and numerous bacterial community compared to healthy patients. In this sense, we reinforce that biofilms that harbour multidrug-resistant bacteria are a major concern in relation to restoring patient health. Thus, prophylactic measures for maintaining oral health are still the best option for reduce the risk of disease.

Graphic Abstract

Co-infection of Newcastle disease virus genotype XIII with low pathogenic avian influenza exacerbates clinical outcome of Newcastle disease in vaccinated layer poultry flocks

Newcastle disease (ND) and avian influenza (AI) are economically important infectious diseases of poultry. Sometime, concomitant secondary viral/or bacterial infections significantly alters the pathobiology of ND and AI in poultry. As of now, the disease patterns and dynamics of co-infections caused by ND virus (NDV, genotype XIII) and Low Pathogenic AI viruses (LPAI, H9N2) are explicitly elusive. Thus, we examined the clinicopathological disease conditions due to these two economically important viruses to understand the complex disease outcomes by virus-virus interactions in vaccinated flocks. The findings of clinicopathological and molecular investigations carried on 37 commercial ND vaccinated poultry flocks revealed simultaneous circulation of NDV and AIV in same flock/bird. Further, molecular characterization of hemagglutinin (HA) and neuraminidase (NA) genes confirmed that all the identified AIVs were of low pathogenicity H9N2 subtype and fusion (F) gene analysis of detected NDVs belong to NDV class II, genotype XIII, a virulent type. The NDV and H9N2 alone or co-infected flocks (NDV + LPAI) exhibit clinical signs and lesions similar to that of virulent NDV except the degree of severity, which was higher in H9N2-NDV co-infected flocks. Additionally, avian pathogenic E. coli and mycoplasma infections were detected in majority of the ailing/dead birds from the co-infected flocks during progression of the clinical disease. Overall, the findings highlight the multi-factorial disease complexity in commercial poultry and suggest the importance of NDV genotype XIII in intensifying the clinical disease in vaccinated birds.

Molecular Survey of Respiratory and Immunosuppressive Pathogens Associated with Low Pathogenic Avian Influenza H9N2 Subtype and Virulent Newcastle Disease Viruses in Commercial Chicken Flocks

The study was carried out in 48 poultry flocks to elucidate the roles of various complicating pathogens involved along with Newcastle disease (ND)/ low pathogenic avian influenza (LPAI) outbreaks. Necropsy was conducted and samples were collected for the isolation of Newcastle disease virus (NDV), Influenza A virus, infectious bronchitis virus (IBV), pathogenic bacteria; molecular detection of infectious laryngotracheitis virus (ILTV), fowl adeno virus (FAV), chicken anaemia virus (CAV), Mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG). The isolation results confirmed that 18/48 flocks (37%) were positive for the presence of hemagglutinating agents. Out of 18 hemagglutination (HA) positive flocks, 11 flocks (61%) were positive for both avian influenza virus (AIV) and NDV; 4 flocks (22%) were positive for NDV; and 3 flocks (17%) were positive for AIV. Sequence analysis of hemagglutinin and neuraminidase genes of AIV revealed that all were belonging to LPAI-H9N2 subtype. Sequence analysis of F gene of NDV revealed that they belong to virulent type. The PCR results confirmed the presence of three to seven etiological agents (CAV, FAV, ILTV, MG, MS and avian pathogenic E. coli along with LPAI/NDV from all the 18 HA-positive flocks. The detection rate of triple, quadruple, quintuple, sextuple and sevenfold infections was 17% (3 flocks), 28% (5 flocks), 11%, (2 flocks) 28% (5 flocks) and 17% (3 flocks), respectively. In conclusion, the disease complex involved more than one pathogen, primarily resulting from the interplay between LPAI-H9N2 and NDV; subsequently this could be exacerbated by co-infection with other agents which may cause exacerbated outbreaks that may otherwise go undetected in field.

Rapid immunochromatographic test strip to detect swimming crab Portunus trituberculatus reovirus

Swimming crab reovirus (SCRV) is the causative agent of a serious disease with high mortality in cultured Portunus trituberculatus. A rapid immunochromatographic assay (ICA) was developed in a competitive assay format and optimized for the detection of SCRV. The gold probe-based ICA test comprised SCRV antigen and goat anti-chicken egg yolk antibody (IgY) sprayed onto a nitrocellulose membrane as the test line and control line, respectively. IgY-gold complexes were deposited onto the conjugate pad as detector reagents. The method showed high specificity with no cross-reactivity with other related aquatic pathogens. The detection limit of the ICA strip was 50 µg ml⁻¹. To evaluate the performance of the ICA test, the strip and an enzyme-linked immunosorbent assay (ELISA) were applied to the same samples (n = 90 crabs). The strip successfully detected SCRV in all of the artificially infected samples. Furthermore, the ICA strip and ELISA tests had high consistency (98.28%). The strip assay requires no instruments and has a detection time of less than 10 min. It is portable and easy to perform in the field. These results indicated that the developed strip could be a promising on-site tool for screening pooled crabs to confirm SCRV infection or disease outbreaks.